^/'/ <i^-^ 
 
 
 h' J" 
 
■^ 
 
Digitized by tine Internet Archive 
 
 in 2010 witii funding from 
 
 Open Knowledge Commons 
 
 fe. 
 
 http://www.archive.org/details/treatiseonhumanpOOdalt 
 
HUMAN PHYSIOLOGY. 
 
A TREATISE 
 
 HUMAN PHYSIOLOGY 
 
 DESIGNED FOR THE USE OF 
 
 STUDENTS AND PMCTITIONERS OF MEDICINE. 
 
 BY 
 
 JOHN C. DALTON, Jr., M. D., 
 
 PROFESSOR OF PHYSIOLOGY AND MICROSCOPIC ANATOMY IN THE COLLEGE OP PHYSICIANS AND SURGEONS, 
 
 NEW YORK; MEMBER OF THE NEW YORK ACADEMY OF MEDICINE; OF THE NEW YORK 
 
 PATHOLOGICAL SOCIETY; OF THE AMERICAN ACADEMY OF ARTS AND SCIENCES, 
 
 BOSTON, MASS. ; AND OP THE BIOLOGICAL DEPARTMENT OF THE 
 
 ACADEMY OF NATURAL SCIENCES OF PHILADELPHIA. 
 
 WITH TWO HUNDRED AND FIFTY-FOUR ILLUSTPuATIONS. 
 
 PHILADELPHIA: 
 BLANCHAUD AND LEA. 
 
 1859. 
 
/rsf 
 
 Entered according to the Act of Congress, in the year 185 9^ by 
 
 BLANCHARD AND LEA, 
 
 in the Office of the Clerk of the District Court of the United States in and for the 
 Eastern District of the State of Pennsylvania. 
 
 PHILADELPHIA: 
 COLLINS, PRINTER, 705 LODGE ALLEY. 
 
TO MY FATHER, 
 
 JOHN C. DALTON, M.D., 
 
 HOMAGE OF HIS LONG AND SUCCESSFUL DEVOTION 
 
 SCIENCE AND ART OF MEDICINE, 
 
 GRATEFUL RECOLLECTION OP HIS PROFESSIONAL PRECEPTS AND EXAMPLE, 
 
 %\lh Bahnu 
 
 IS RESPECTFULLY AND AFFECTIONATELY 
 
 INSCRIBED. 
 
'mm 
 
PREFACE. 
 
 This volume is offered to the medical profession of the United 
 States, as a text-book for students, and also as a means of commu- 
 nicating, in a condensed form, such new facts and ideas in physio- 
 logy, as have marked the progress of the science within a recent 
 period. Many of these topics are of great practical importance to 
 the medical man, as influencing, in various ways, his views on 
 pathology and therapeutics ; and they are all of interest for the 
 physician who desires to keep pace with the annual advance of his 
 profession, as indicating the present position and extent of one of 
 the most progressive of the departments of medicine. 
 
 It has been the object of the author, more particularly, to pre- 
 sent, at the same time with the conclusions which physiologists 
 have been led to adopt on any particular subject, the experimental 
 basis upon which those conclusions are founded ; and he has en- 
 deavored, so far as possible, to establish or corroborate them by 
 original investigation, or by a repetition of the labors of others. 
 This is more especially the case in that part of the book (Section 
 I.) devoted to the function of Nutrition ; and as a general thing, 
 throughout the work, any statement of experimental facts, not 
 expressly referred to the authority of some other writer, is given 
 by the author as the result of direct personal observation. 
 
 The illustrations for the work have been prepared with special 
 reference to the subject-matter ; and it is hoped that they will be 
 found of such a character as materially to assist the student in 
 comprehending the most important and intricate parts of the sub- 
 ject. It is more particularly in the departments of the Nervous 
 System and Embryonic Development that simple, clear, and faithful 
 
Vlll PREFACE. 
 
 illustrations are indispensable for tlie proper understanding of the 
 printed descriptions ; the latter being often necessarily somewhat 
 intricate, and requiring absolutely the assistance of properly 
 arranged figures and diagrams. Of the two hundred and fifty-four 
 illustrations in the present volume, only eleven have been bor- 
 rowed from other writers, to whom they will be found duly 
 credited in the list of woodcuts. 
 
 Of the remaining illustrations, prepared expressly for the pre- 
 sent work, the drawings of anatomical structures, crystals, and 
 microscopic views generally, were all taken from nature. The 
 diagrams were arranged, for purposes of convenience, in such 
 a manner as to illustrate known anatomical or physiological ap- 
 pearances, in the most compact and intelligible form. 
 
 Physiological questions which are in an altogether unsettled 
 state, as well as purely hypothetical topics, have been purposely 
 avoided, as not coming within the plan of this work, nor as calcu- 
 lated to increase its usefulness. 
 
 New York, January 1, 1859. 
 
CONTENTS. 
 
 INTRODUCTION. 
 
 PAGE 
 
 Definition of Physiology — Its mode of study — Nature of Vital Phenomena — 
 Division of the subject ....... 17-27 
 
 SECTION I. 
 . NUTRITION. 
 
 CHAPTER I. 
 
 PROXIMATE PRINCIPLES IN GENERAL. 
 
 Definition of Proximate Principles — Mode of their extraction — Manner in which 
 they are associated with each other — Natural variation in their relative 
 quantities — Three distinct classes of proximate principles . . 29-36 
 
 CHAPTER II. 
 
 PROXIMATE PRINCIPLES OP THE FIRST CLASS. 
 
 Inorganic Substances — Water — Chloride of Sodium — Chloride of Potassium — 
 Phosphate of Lime — Carbonate of Lime — Carbonate of Soda — Phosphates of 
 Magnesia, Soda, and Potass — Inorganic proximate principles not altered in 
 the body — Their discharge — Nature of their function . . . 37-46 
 
 CHAPTER III. 
 
 PROXIMATE PRINCIPLES OP THE SECOND CLASS. 
 
 Starch — Percentage of starch in different kinds of food — Varieties of this 
 substance — Properties and reactions of starch — Its conversion into sugar — 
 Sugar — Varieties of sugar — Physical and chemical properties — Proportion 
 in different kinds of food — Fats — Varieties — Properties and reactions of fat 
 — Its crystallization — Proportion in different kinds of food — Its condition in 
 the body — Internal production of fat — Origin and destination of proximate 
 principles of this class ....... 47-62 
 
X CONTENTS. 
 
 CHAPTER lY. 
 
 PROXIMATE PRINCIPLES OF THE THIRD CLASS. 
 
 PAGE 
 
 General characters of organic substances — Their chemical constitution — Hygro- 
 scopic properties — Coagulation — Catalysis — Fermentation — Putrefaction — 
 Fibrin — Albumen — Casein — Globuline — Pepsine — Pancreatine — Mucosine — 
 Osteine — Cartilagine — Mnsculine — Hsematine — Melanine — Bill verdine — 
 Urosacine — Origin and destruction of proximate principles of this class 63-72 
 
 CHAPTER V. 
 
 OF FOOD. 
 
 Importance of inorganic substances as ingredients of food — Of saccharine and 
 starchy substances — Of fatty matters — Insufiiciency of these substances 
 when used alone — Effects of an exclusive non-nitrogenous diet — Organic 
 substances also insufficient by themselves — Experiments of Magendie on 
 exclusive diet of gelatine or fibrin — Food requires to contain all classes of 
 proximate principles — Composition of various kinds of food — Daily quantity 
 of food required by man — Digestibility of food — Efifect of cooking . 73-82 
 
 CHAPTER Y I. 
 
 DIGESTION. 
 
 Nature of digestion — Digestive apparatus of fowl — Of ox — Of man — Mastica- 
 tion — Varieties of teeth — Effect of mastication — Saliva — Its composition — 
 Daily quantity produced — Its action on starch — Effect of its suppression — 
 Function of the saliva — Gastric Juice, and Stomach Digestion — Structure of 
 gastric mucous membrane — Dr. Beaumont's experiments on St. Martin — 
 Artificial gastric fistulse — Composition and properties of gastric juice — Its 
 action on albuminoid substances — Peristaltic action of stomach — Time re- 
 quired for digestion — Daily quantity of gastric juice — Influences modifying 
 its secretion — Intestinal Juices, and the Digestion of Sugar and Starch — 
 Follicles of intestine — Properties of intestinal juice — Pancreatic Juice, and 
 THE Digestion of Fat — Composition and properties of pancreatic juice — Its 
 action on oily matters — Successive changes in intestinal digestion . 83-127 
 
 CHAPTER YII. 
 
 ABSORPTION. 
 
 Closed follicles and villi of small intestine — Peristaltic motion — Absorption 
 by bloodvessels and lymphatics — Chyle — Lymph — Absorbent system — Lac- 
 teals and lymphatics — Absorption of fat — Its accumulation in the blood 
 during digestion — Its final decomposition and disappearance ; . 128-140 
 
CONTENTS. XI 
 
 CHAPTER VIII. 
 
 THE BILE. 
 
 PAGE 
 
 Physical properties of the bile — Its compositiou — Biliverdine — Cholesterin — 
 Biliary salts — Their mode of extraction — Crystallization — Glyko-cholate of 
 soda — Tauro-cholate of soda — Biliary salts in diiferent species of animals 
 and in man — Tests for bile — Variations and functions of bile — Daily quan- 
 tity — Time of its discharge into intestine — Its disappearance from the ali- 
 mentary canal — Its reabsorption — Its ultimate decomposition . . 141-164 
 
 CHAPTER IX. 
 
 FORMATION OF SUGAR IN THE LIVER. 
 
 Existence of sugar in li^rer of all animals — Its percentage — Internal origin of 
 liver-sugar — Its production after death — Glycogenic matter of the liver — Its 
 properties and composition — Absorption of liver-sugar by hepatic veins — 
 Its accumulation in the blood during digestion — Its final decomposition and 
 disappearance . . . . . . . . 165-172 
 
 CHAPTER X. 
 
 THE SPLEEN. 
 
 Capsule of Spleen — Variations in size of the organ — Its internal structure — 
 Malpighian bodies of the spleen — Action of spleen on the blood — Effect of 
 its extirpation ........ 173-177 
 
 CHAPTER XI. 
 
 THE BLOOD. 
 
 Red Globules of the blood — Their microscopic characters — Structure and com- 
 position — Variations in size in different animals — White Globules of the 
 blood — Independence of the two kinds of blood-globules — Plasma — Its com- 
 position — Fibi'in — Albumen — Fatty matters — Saline ingredients — Extractive 
 matters — Coagulation of the Blood — Separation of clot and serum — Influ- 
 ences hastening or retarding coagulation — Coagulation not a commencement 
 of organization — Formation of buflfy coat — Entire quantity of blood in body 
 
 178-196 
 
 CHAPTER XII. 
 
 RESPIRATION. 
 
 Respiratory apparatus of aquatic and air-breathing animals — Structure of 
 lungs in human subject — Respiratory movements of chest — Of glottis — 
 Changes in the air during respiration — Changes in the blood — Proportions 
 of oxygen and carbonic acid, in venous and arterial blood-r— Solution of gases 
 by the blood-globules — Origin of carbonic acid in the blood — Its mode of 
 production — Quantity of carbonic acid exhaled from the body — Variations 
 according to age, sex, temperature, &c. — Respiration by the skin . 197-217 
 
XU CONTENTS. 
 
 CHAPTER XIII. 
 
 ANIMAL HEAT. 
 
 PAGE 
 Standard temperature of animals — How maintained — Production of heat by- 
 Vegetables — Mode of generation of animal heat — Theory of combustion — 
 Objections to this theory — No oxidation in vegetables during production of 
 heat — Quantities of oxygen and carbonic acid in animals do not correspond 
 with each other — Production of animal heat a local process — Depends on 
 the chemical phenomena of nutrition ..... 218-228 
 
 CHAPTER XIY. 
 
 THE CIRCULATIOx^. 
 
 Circulatory apparatus of fish — Of reptiles — Of mammalians — Course of blood 
 through the heart — Action of valves — Sounds of heart — Movements — Im- 
 pulse — Successive pulsations — Arterial system — Movement of blood through 
 the arteries — Arterial pulse — Rapidity of arterial circulation — The veins — 
 Causes of movement of blood in the veins — Rapidity of venous current — 
 Capillary circulation — Phenomena and causes of cap>illary circulation — 
 Rapidity of entire circulation — Local variations in different parts . 229-264 
 
 CHAPTER XV. 
 
 SECRETION. 
 
 Nature of secretion — Variations in activity — Mucus — Sebaceous matter — Per- 
 spiration — Tears — Milk — Secretion of bile — Anatomical peculiarities . 265-281 
 
 CHAPTER XYI. 
 
 EXCRETION. 
 
 Nature of excretion — Excrementitious substances — Effect of their retention 
 — Urea — Its source — Conversion into carbonate of ammonia — Daily quan- 
 tity of urea — Creatine — Creatinine— Urate of soda — Urates of potass and 
 ammonia — General characters of the urine — Its composition — Variations — 
 Accidental ingredients of the urine — Acid and alkaline fermentktions — 
 Final decomposition of the urine ..... 282-304 
 
CONTENTS. Xlll 
 
 SECTION II. 
 NERVOUS SYSTEM. 
 
 CHAPTER I. 
 
 GENERAL CHARACTER AND FUNCTIONS OF THE NERVOUS SYSTEM. 
 
 PAGE 
 
 Nature of the function performed by nervous system — Two kinds of nervous 
 tissue — Fibres of white substance — Their minute structure — Division and 
 inosculation of nerves — Gray substance — Nervous system of radiata — Of 
 mollusca — Of articulata — Of mammalia and human subject — Structure of 
 encepbalon — Connections of its different parts .... 305-327 
 
 CHAPTER II. 
 
 OF NERVOUS IRRITABILITY, AND ITS MODE OP ACTION. 
 
 Irritability of muscles — How esliibited — Influences wliich exbaust and destroy 
 it — Nervous irritability — How exhibited — Continues after death — Exhausted 
 by repeated excitement — Influence of direct and inverse electrical currents 
 — Nervous irritability distinct from muscular irritability — Nature of the 
 nervous force — Its resemblance to electricity — Difi'erences between the two 
 
 328-339 
 
 CHAPTER III. 
 
 THE SPINAL CORD. 
 
 Distinct seat of sensation and motion in nervous system — Sensibility and 
 excitability — Distinct seat of sensibility and excitability in spinal cord — 
 Crossed action of spinal cord — Independent and associated action of motor 
 and sensitive filaments — Reflex action of spinal cord — How manifested dur- 
 ing disease — Influence in health on sphincters, voluntary muscles, urinary 
 bladder, &c. . . . . . . . . 340-356 
 
 CHAPTER lY. 
 
 THE BRAIN. 
 
 Seat of sensibility and excitability in difi'erent parts of the encephalon — Olfac- 
 tory ganglia — Optic thalami — Corpora striata — Hemispheres — Remarkable 
 cases of injury of hemispheres — Efi'ect of their removal — Imperfect develop- 
 ment in idiots — Aztec children — Theory of phrenology — Cerebellum — Efi"ect 
 of its injury or removal — Comparative development in different classes — 
 Tubercula quadrigemina — Tuber annulare — Medulla oblongata — Three kinds 
 of reflex action in nervous system ..... 357-384 
 
xiv CONTENTS. 
 
 CHAPTER Y. 
 
 THE CRANIAL NERVES. 
 
 PAGE 
 
 Olfactory nerves — Optic nerves — Auditory nerves — Classification of cranial 
 nerves — Motor Nerves of the Head — Motor ocull communis — Patheticus — 
 Motor externtis — Small root of fifth pair— Facial nerve — Sublingual nerve 
 — Spinal accessory — Sensitive Nerves of the Head — Fifth pair — Its sensi- 
 bility — Effect of division — Influence on the organ of sight — Glosso-pharyn- 
 geal nerve — Pneumogastric — Its distribution — Influence on pharynx and 
 oesophagus — On larynx — On lungs — On stomach and digestion . 385-413 
 
 CHAPTER YI. 
 
 SYSTEM OF THE GREAT SYMPATHETIC. 
 
 Ganglia of the great sympathetic — Distribution of its nerves — Sensibility and 
 excitability of sympathetic — Sluggish action of this nerve — Influence over 
 organs of special sense — Elevation of temperature after division of sympa- 
 thetic — Contraction of pupil following the same operation — Reflex actions 
 taking place through the great sympathetic .... 414-425 
 
 SECTION III. 
 KEPRODUCTION. 
 
 CHAPTER I. 
 
 ON THE NATURE OF REPRODUCTION, AND THE ORIGIN OF PLANTS AND 
 
 ANIMALS. 
 
 Nature and objects of the function of reproduction — Mode of its accomplish- 
 ment — By generation from parents — Spontaneous generation — Mistaken in- 
 stances of this mode of generation — Production of infusoria— Conditions of 
 their development — Schultze's experiment on generation of infusoria — Pro- 
 duction of animal and vegetable parasites— Encysted entozoa — Trichina 
 spiralis — Tsnia — Cysticercus— Production of taenia from cysticercus — Of 
 cysticercus from eggs of taenia — Plants and animals always produced by 
 generation from parents ....... 427-441 
 
 CHAPTER II. 
 
 ON SEXUAL GENERATION, AND THE MODE OF ITS ACCOMPLISHMENT. 
 
 Sexual apparatus of plants— Fecundation of the germ — Its development into 
 a new plant — Sexual apparatus of animals — Ovaries and testicles — Uni- 
 sexual and bisexual species — Distinctive characters of the two sexes 442-445 
 
CONTENTS. XV 
 
 CHAPTER III. 
 
 ON THE EGG, AND THE FEMALE ORGANS OF GENERATION. 
 
 PAGE 
 Size and appearance of the egg — Vitelline membrane — Vitellus — Germinative 
 vesicle — Germinative spot — Ovaries — Graafian Follicles — Oviducts — Female 
 generative organs of frog — Ovary and oviduct of fowl — Changes in the egg, 
 while passing through the oviduct — Complete fowl's egg — Uterus and ova- 
 ries of the sow — Female generative apparatus of the human subject — Fal- 
 lopian tubes— Body of the uterus— Cervix of the uterus . . 446-457 
 
 CHAPTER lY. 
 
 ON THE SPERMATIC FLUID, AND THE MALE ORGANS OF GENERATION, 
 
 The spermatozoa — Their varieties in different species — Their movement — For- 
 mation of spermatozoa in the testicles — Accessory male organs of generation 
 — Epididymis — Vas deferens — Vesiculae seminales — Prostate — Cowper's 
 glands — Function of spermatozoa — Physical conditions of fecundation 458-464 
 
 CHAPTER y. 
 
 ON PERIODICAL OVULATION, AND THE FUNCTION OP MENSTRUATION. 
 
 Periodical Ovulation — Pre-existence of eggs in the ovaries of all animals — 
 Their increased development at the period of puberty — Their successive 
 ripening and periodical discharge — Discharge of eggs independently of sexual 
 intercourse — Rupture of Graafian follicle, and expulsion of the egg — Pheno- 
 mena of cestruation — Menstruation — Correspondence of menstrual periods 
 with periods of ovulation in the lower animals — Discharge of egg during 
 menstrual period — Conditions of its impregnation, after leaving the ovary 
 
 465-477 
 
 CHAPTER Y I. 
 
 ON THE CORPUS LUTEUM OF MENSTRUATION AND PREGNANCY. 
 
 Corpus Luteum of Menstruation — Discharge of blood into the ruptured Graafian 
 follicle — Decolorization of the clot, and hypertrophy of the membrane of the 
 vesicle — Corpus luteum of menstruation, at the end of three weeks — Yellow 
 coloration of convoluted wall — Corpus luteum of menstruation at the end 
 of four weeks — Shrivelling and condensation of its tissues — Its condition at 
 the end of nine weeks — Its final atrophy and disappearance — Corpus Luteum 
 OF Pregnancy — Its continued development after the third week — Appearance 
 at the end of second month — Of fourth month — At the termination of preg- 
 nancy — Its atrophy and disappearance after delivery — Distinctive characters 
 of corpora lutea of menstruation and pregnancy . . . 478-487 
 
Xvi CONTENTS. 
 
 CHAPTER VII. 
 
 ON THE DEVELOPMENT OF THE IMPREGNATED EGG. 
 
 PAGE 
 
 Segmentation of the vitellus — Formation of blastodermic membrane. — Two 
 layers of blastodermic membrane — Thickening of external layer — Formation 
 of primitive trace — Dorsal plates — Abdominal plates — Closure of dorsal and 
 abdominal plates on the median line — Formation of intestine — Of mouth 
 and anus — Of organs of locomotion — Continued development of organs, after 
 leaving the egg ....... 488-497 
 
 CHAPTER YIII. 
 
 THE UMBILICAL VESICLE. 
 
 Separation of vitelline sac into two cavities — Closure of abdominal walls, and 
 formation of umbilical vesicle in fish — Mode of its disappearance after hatch- 
 ing — Umbilical vesicle in human embryo — Formation and growth of pedicle 
 — Disappearance of umbilical vesicle during embryonic life . . 498-500 
 
 CHAPTER IX. 
 
 AMNION AND ALLANTOIS — DEVELOPMENT OF THE CHICK. 
 
 Necessity for accessory organs in the development of birds and quadrupeds — 
 Formation of amniotic folds — Their union and adhesion — Growth of allantois 
 from lower part of intestine — Its vascularity — Allantois in the egg of the 
 fowl — Respiration of the egg — Absorption of calcareous matter from the 
 shell — Ossification of skeleton — Fracture of egg-shell — Casting off of 
 amnion and allantois . . . . . . . 501-509 
 
 C HAPTER X. 
 
 DEVELOPMENT OF THE EGG IN THE HUMAN SPECIES — FORMATION OF THE 
 
 CHORION. 
 
 Conversion of allantois into chorion — Subsequent changes of the chorion — 
 Its villosities — Formation of bloodvessels in villosities — Action of villi of 
 chorion in providing for nutrition of foetus — Proofs that the chorion is formed 
 from the allantois — Partial disappearance of villosities of chorion, and 
 changes in its external surface . ..... 510-515 
 
 CHAPTER XI. 
 
 DEVELOPMENT OF UTERINE MUCOUS MEMBRANE — FORMATION OF THE DECIDUA. 
 
 Structure of uterine mucous membrane — Uterine tubules — Thickening of 
 uterine mucous membrane after impregnation — Decidua vera — Entrance of 
 egg into uterus — Decidua reflexa— Inclosure of egg by decidua reflexa — 
 Union of chorion with decidua — Changes in the relative development of dif- 
 ferent portions of chorion and decidua ..... 516-522 
 
CONTENTS. XVll 
 
 CHAPTER XII. 
 
 THE PLACENTA. 
 
 PAGE 
 
 Nourisliment of foetus by maternal and foetal vessels — Arrangement of the 
 vascular membranes in different species of animals — Membranes of foetal 
 pig — Cotyledon of cow's uterus — Development of foetal tufts in liuman pla- 
 centa — Development of uterine sinuses — Relation of foetal and maternal 
 bloodvessels in tlie placenta — Proofs that the maternal sinuses extend 
 through the whole thickness of the placenta — Absorption and exhalation 
 by the placental vessels . ..... 523-531 
 
 CHAPTER XIII. 
 
 DISCHARGE OF THE OVUM, AND INVOLUTION OF THE UTERUS. 
 
 Enlargement of amniotic cavity — Contact of amnion and chorion — Amniotic 
 fluid — Movements of foetus — Union of decidua vera and reflexa — Expulsion 
 of the ovum and discharge of decidual membrane — Separation of the pla- 
 centa — Formation of new mucous membrane underneath the old decidua — 
 Fatty degeneration and reconstruction of muscular walls of uterus 532-538 
 
 CHAPTER XIV. 
 
 DEVELOPMENT OF THE EMBRYO — NERVOUS SYSTEM, ORGANS OF SENSE, 
 SKELETON AND LIMBS. 
 
 Formation of spinal cord and cerebro-spinal axis — Three cerebral vesicles — 
 Hemispheres — Optic thalami — Tubercula quadrigemina — Cerebellum — Me- 
 dulla oblongata — Eye — Pupillary membrane — Skeleton — Chorda dorsalis — 
 Bodies of the vertebrae — Laminae and ribs — Spina bifida — Anterior and pos- 
 terior extremities — Tail — Integument — Hair — Vernix caseosa — Exfoliation 
 of epidermis ........ 539-545 
 
 CHAPTER XY. 
 
 DEVELOPMENT OP THE ALIMENTARY CANAL AND ITS APPENDAGES. 
 
 Formation of intestine — Stomach — Duodenum — Convolutions of intestine — 
 Large and small intestine — Caput coli and appendix vermiformis — Umbi- 
 lical hernia — Formation of urinary bladder — Urachus — Vesico-rectal septum 
 — Perineura — Liver — Secretion of bile — Gastric juice — Meconium — Glyco- 
 genic function of liver — Diabetes of foetus — Pharynx and oesophagus — Dia- 
 phragm — Diaphragmatic hernia — Heart and pericardium — Ectopia cordis — 
 Development of the face ...... 546-555 
 
 1 
 
XVlll CONTENTS. 
 
 CHAPTER XVI. 
 
 DEVELOPMENT OF THE KIDNEYS, WOLFFIAN BODIES, AND INTERNAL ORGANS 
 
 OF GENERATION. 
 
 PAGE 
 
 Wolffian bodies — Their structure — First appearance of kidneys — Growth of 
 kidneys, and atrophy of Wolffian bodies — Testicles and ovaries — Descent of 
 the testicles — Tunica vaginalis testis — Congenital inguinal hernia — Descent 
 of the ovaries — Development of the uterus .... 556-565 
 
 CHAPTER XVII. 
 
 DEVELOPMENT OF THE CIRCULATORY APPARATUS. 
 
 First, or vitelline circulation — Area vasculosa — Sinus terminalis — Vitelline 
 circulation of fish — Arrangement of arteries and veins in body of foetus — 
 Second, or placental circulation — Omphalo-mesenteric arteries and veins — 
 Circulation of the umbilical vesicle — Of the allantois and placenta — Umbi- 
 lical arteries and veins — Third, or adult circulation — Portal and pulmonary 
 systems — Development of the arterial system — Development of the venous 
 system — Changes in the hepatic circulation — Portal vein — Umbilical vein 
 — Ductus venosus — Changes in the cardiac circulation — Division of heart 
 into right and left cavities — Aorta and pulmonary artery — Ductus arteriosus 
 — Foramen ovale and Eustachian valve — Changes in circulation at the 
 period of birth . . . . . . . . 566-587 
 
 C HAPTER XVIII. 
 
 DEVELOPMENT OF THE BODY AFTER BIRTH. 
 
 Condition of foetus at birth — Gradual establishment of respiration — Inactivity 
 of the animal functions — Preponderance of reflex actions in the nervous 
 system — Peculiarities in the action of drugs on infant — DiflTerence in rela- 
 tive size of organs, in infaiat and adult — Withering and separation of umbi- 
 lical cord — Exfoliation of epidermis — First and second sets of teeth — Sub- 
 sequent changes in osseous, muscular and tegumentary systems, and gene- 
 ral development of the body ...... 588-591 
 
LIST OF ILLUSTRATIONS, 
 
 ALL OF WHICH HAVE BEEN PREPARED FROM ORIGINAL DRAWINGS, WITH THE 
 EXCEPTION OF ELEVEN, CREDITED TO THEIR AUTHORITIES. 
 
 FIG. 
 
 1. Fibula tied iu a knot, after maceration in a dilute acid 
 
 2. Grains of potato starcli 
 
 3. Starch grains of Bermuda arrowroot 
 
 4. Starcli grains of wheat flour 
 
 5. Starch grains of Indian corn 
 
 6. Starch grains from wall of lateral ventricle 
 
 7. Stearine 
 
 8. Oleaginous principles of human fat 
 
 9. Human adipose tissue 
 
 10. Chyle 
 
 11. Globules of cow's milk 
 
 12. Cells of costal cartilages 
 
 13. Hepatic cells 
 
 14. Uriniferous tubules of dog 
 
 15. Muscular fibres of human uterus 
 
 16. Alimentary canal of fowl . 
 
 17. Compound stomach of ox 
 
 18. Human alimentary canal 
 
 19. Skull of rattlesnake 
 
 20. Skull of polar bear 
 
 21. Skull of the horse 
 
 22. Molar tooth of the horse . 
 
 23. Human teeth — upper jaw 
 
 24. Buccal and glandular epithelium deposited from saliva 
 
 25. Gastric mucous membrane, viewed from above 
 
 26. Gastric mucous membrane, in vertical section 
 
 27. Mucous membrane of pig's stomach 
 
 28. Gastric tubules from pig's stomach, pyloric portion 
 
 29. Gastric tubules from pig's stomach, cardiac portion 
 
 30. Confervoid vegetable, growing in gastric juice 
 
 31. Follicles of Lieberkiihn . 
 
 32. Brunner's duodenal glands 
 
 33. Contents of stomach, during digestion of meat 
 
 34. From duodenum of dog, during digestion of meat 
 
 35. From middle of small intestine . 
 
 From Rymer Jones 
 From Achille Richard 
 
 PAGE 
 
 43 
 
 48 
 
 48 
 
 49 
 
 49 
 
 50 
 
 55 
 
 56 
 
 . 58 
 
 58 
 
 59 
 
 59 
 
 60 
 
 60 
 
 61 
 
 85 
 
 86 
 
 87 
 
 89 
 
 90 
 
 90 
 
 90 
 
 91 
 
 92 
 
 101 
 
 101 
 
 101 
 
 102 
 
 102 
 
 108 
 
 119 
 
 120 
 
 126 
 
 126 
 
 127 
 
XX 
 
 LIST OF ILLUSTRATIONS. 
 
 FIG. 
 
 36. From last quarter of small intestine 
 
 37. One of the closed follicles of Peyer's patches 
 
 38. Glandulse agminatse 
 
 39. Extremity of intestinal villus 
 
 40. Panizza's experiment on absorption by bloodvessels 
 
 41. Chyle, from commencement of thoracic duct 
 
 42. Lacteals, thoracic diict, &c. 
 
 43. Lacteals and lymphatics . 
 
 44. Intestinal epithelium, in intervals of digestion 
 
 45. Intestinal epithelium, during digestion . 
 
 46. Cholesteriu .... 
 
 47. Ox-bile, crystallized 
 
 48. Glyko-cholate of soda from ox-bile 
 
 49. Glyko-cholate and tauro-cholate of soda, from ox-bile 
 
 50. Dog's bile, crystallized 
 
 51. Human bile, showing resinous matters . 
 
 52. Crystalline and resinous biliary substances, from dog's intestine 
 
 53. Duodenal iistula .... 
 
 54. Human blood-globules 
 
 55. The same, seen out of focus 
 
 56. The same, seen within the focus . 
 
 57. The same, adhering together in rows 
 
 58. The same, swollen by addition of water . 
 
 59. The same, shrivelled by evaporation 
 
 60. Blood-globules of frog 
 
 61. White globules of the blood 
 
 62. Coagulated fibrin . 
 
 63. Coagulated blood .... 
 
 64. Coagulated blood, after separation of clot and serum 
 
 65. Recent coagulum .... 
 
 66. Coagulated blood, clot buffed and cupped 
 
 67. Head and gills of men'obranchus . 
 
 68. Lung of frog .... 
 
 69. Human larynx, trachea, bronchi, and lungs 
 
 70. Single lobule of human lung 
 
 71. Diagram illustrating the respiratory movements 
 
 72. Small bronchial tube 
 
 73. Human larynx, with glottis closed 
 
 74. The same, with glottis open 
 
 75. Human larynx ; posterior view . 
 
 76. Circulation of fish 
 
 77. Circulation of reptiles 
 
 78. Circulation of mammalians 
 
 79. Human heart, anterior view 
 
 80. Human heart, posterior view 
 
 81. Right auricle and ventricle, tricuspid valve open, arterial valves closed 
 
 82. Right auricle and ventricle, tricuspid valve closed, arterial valves open 
 
 83. Course of blood through the heart 
 
 84. Illustrating production of valvular sounds 
 
 85. Heart of frog, in relaxation 
 
LIST OF ILLUSTRATIONS. 
 
 XXI 
 
 FIG. 
 
 
 
 
 PAGE 
 
 86. Heart of frog, in contraction ..... 
 
 
 241 
 
 87. Simple looped fibres ..... 
 
 
 
 241 
 
 88. Bullock's heart, showing superficial muscular fibres 
 
 
 
 242 
 
 89. Left ventricle of bullock's heart, showing deep fibres . 
 
 
 
 242 
 
 90. Diagram of circular fibres of the heart . 
 
 
 
 243 
 
 91. Converging fibres of the apex of the heart 
 
 
 
 243 
 
 92. Arterial circulation ..... 
 
 
 
 248 
 
 93. Arteiy in pulsation ..... 
 
 
 
 248 
 
 94. Volkmann's apparatus ..... 
 
 
 
 251 
 
 95. The same ...... 
 
 
 
 251 
 
 96. Vein, with valves open ..... 
 
 
 
 253 
 
 97. Vein, with valves closed .... 
 
 
 
 253 
 
 98. Small artery, with capillary branches . 
 
 
 
 255 
 
 99. Capillary network . . . 
 
 
 
 256 
 
 100. Capillary circulation .... 
 
 
 
 257 
 
 101. Diagram of the circulation 
 
 
 
 264 
 
 102. Follicles of a compound mucous glandule . From Kolliker 268 
 
 103. Meibomian glands .... From Ludovic 270 
 
 104. Perspiratory gland . . . From Todd and Bowman 271 
 
 105. Glandular structure of mamma . . . • 
 
 
 274 
 
 106. Colostrum corpuscles .... 
 
 
 
 275 
 
 107. Milk-globules ..... 
 
 
 
 276 
 
 108. Division of portal vein in liver . 
 
 
 
 279 
 
 109. Lobule of liver . , 
 
 
 
 280 
 
 110. Hepatic cells ..... 
 
 
 
 281 
 
 111. Urea .... From Lehmann (Funke's Atlas) 285 
 
 112. Creatine .... From Lehmann (Funke's Atlas) 287 
 
 113. Creatinine . . . From Lehmann (Funke's Atlas) 288 
 
 114. Urate of soda ........ 289 
 
 115. Uric acid ..... 
 
 
 
 
 . 296 
 
 116. Oxalate of lime .... 
 
 
 
 
 . 302 
 
 117. Phosphate of magnesia and ammonia . 
 
 
 
 
 . 304 
 
 118. Nervous filaments, from brain . 
 
 
 
 
 . 309 
 
 119. Nervous filaments, from sciatic nerve . 
 
 
 
 
 . 310 
 
 120. Division of a nerve 
 
 
 
 
 . 311 
 
 121. Inosculation of nerves . 
 
 
 
 
 . 312 
 
 122. Nerve cells .... 
 
 
 
 
 . 312 
 
 123. Nervous system of starfish 
 
 
 
 
 . 313 
 
 124. Nervous system of aplysia 
 
 
 
 
 . 315 
 
 125. Nervous system of centipede 
 
 
 
 
 . 316 
 
 126. Cerebro-spinal system of man . 
 
 
 
 
 . 319 
 
 127. Spinal cord .... 
 
 
 
 
 . 320 
 
 128. Brain of alligator 
 
 
 
 
 . 322 
 
 129. Brain of rabbit .... 
 
 
 
 
 . 323 
 
 130. Medulla oblongata of human brain 
 
 
 
 
 . 324 
 
 131. Diagram of human brain 
 
 
 
 
 . 326 
 
 132. Experiment showing irritability of muscles 
 
 
 
 
 . 329 
 
 133. Experiment showing irritability of nerve 
 
 
 
 
 . 331 
 
 134. Action of direct and inverse currents 
 
 
 
 
 . 334 
 
 135. Diagram of spinal cord and nerves 
 
 
 
 
 . 342 
 
XXll 
 
 LIST OF ILLUSTKATIONS. 
 
 FIG. 
 
 136. Spinal cord in vertical section . 
 
 137. Experiment, showing effect of poisons on nerves 
 
 138. Pigeon, after removal of the hemispheres 
 
 139. Aztec children 
 
 140. Brain in situ 
 
 141. Transverse section of brain 
 
 142. Pigeon, after removal of the cerebellum 
 
 143. Inferior surface of brain of cod . 
 
 144. Inferior surface of brain of fowl . 
 
 145. Course of optic nerves in man . 
 
 146. Facial nerve 
 
 147. Distribution of fifth nerve upon the face 
 
 148. Pneumogastric nerve 
 
 149. Great sympathetic 
 
 150. Cat, after division of sympatlietic in the neck 
 
 151. Different kinds of infusoria 
 
 152. Experiment on spontaneous generation . . From Schultze 
 
 153. Trichina spiralis . 
 
 154. Taenia .... 
 
 155. Cysticercus, retracted 
 
 156. Cysticercus, unfolded 
 
 157. Blossom of Convolvulus purpureus 
 
 158. Single articulation of Taenia crassicollis 
 
 159. Human ovum 
 
 160. Human ovum, ruptured by pressure 
 
 161. Female generative organs of frog 
 
 162. Mature frogs' eggs 
 
 163. Female generative organs of fowl 
 
 164. Fowl's egg 
 
 165. Uterus and ovaries of the sow . 
 
 166. Generative organs of human female 
 
 167. Spermatozoa 
 
 168. Graafian follicle . 
 
 169. Ovary with Graafian follicle ruptured 
 
 170. Graafian follicle, ruptured and filled with blood 
 
 171. Corpus luteum, three weeks after menstruation 
 
 172. Corpus luteum, four weeks after menstruation 
 
 173. Corpus luteum, nine weeks after menstruation 
 
 174. Corpus luteum of pregnancy, at end of second month 
 
 175. Corpus luteum of pregnancy, at end of fourth month 
 
 176. Corpus luteum of pregnancy, at term 
 
 177. Segmentation of the vitellus 
 
 178. Impregnated egg, showing embryonic spot 
 
 179. Impregnated egg, showing two layers of blastodermic membrane 
 
 180. Impregnated egg, farther advanced 
 
 181. Frog's egg, at an early period 
 
 182. Egg of frog, in process of development 
 
 183. Egg of frog, farther advanced 
 
 184. Tadpole, fully developed 
 
 185. Tadpole, changing into frog 
 
LIST OF ILLUSTRATIONS. 
 
 FIG. 
 
 186. Perfect frog .... 
 
 187. Egg of fish .... 
 
 188. Young fish, with umbilical vesicle 
 
 189. Human embryo, with umbilical vesicle 
 
 190. Fecundated egg, showing formation of amnion 
 
 191. Fecundated egg, showing commencement of allantois 
 
 192. Fecundated egg, with allantois nearly complete 
 
 193. Fecundated egg, with allantois fully formed 
 
 194. Egg of fowl, showing area vasculosa 
 
 195. Egg of fowl, showing allantois, amnion, &c. 
 
 196. Human ovum, showing formation of chorion 
 
 197. Human chorion . 
 
 198. Villosity of chorion 
 
 199. Human ovum, at end of third month 
 
 200. Uterine mucous membrane 
 
 201. Uterine tubules . 
 
 202. Impregnated uterus, showing formation of decidua 
 . 203. Impregnated uterus, showing formation of decidua reflexa 
 
 204. Impregnated uterus, with decidua reflexa complete 
 
 205. Impregnated uterus, showing union of chorion and decidua 
 
 206. Pregnant uterus, showing formation of placenta 
 
 207. Foetal pig, with membranes 
 
 208. Cotyledon of cow's uterus 
 
 209. Foetal tuft of human placenta . 
 
 210. Vertical section of placenta 
 
 211. Human ovum, at end of first month 
 
 212. Human ovum, at end of third month 
 
 213. Gravid human uterus and contents 
 
 214. Muscular fibres of unimpregnated uterus 
 
 215. Muscular fibres of human uterus, ten days after parturition 
 
 216. Muscular fibres of human uterus, three weeks after parturition 
 
 217. Formation of cerebro-spinal axis 
 
 218. Formation of cerebro-spinal axis 
 
 219. Foetal pig, showing brain and spinal cord 
 
 220. Foetal pig, showing brain and spinal cord 
 
 221. Head of foetal pig 
 
 222. Brain of adult pig 
 
 223. Formation of alimentary canal . 
 
 224. Head of human embryo, at twenty days . . From Longet 
 
 225. Head of human embryo, at end of first month . . From Longet 
 
 226. Head of human embryo, at end of second month 
 
 227. Foetal pig, showing Wolfiian bodies 
 
 228. Foetal pig, showing first appearance of kidneys 
 
 229. Internal organs of generation 
 
 230. Internal organs of generation 
 
 231. Formation of tunica vaginalis testis 
 
 232. Congenital inguinal hernia 
 
 233. Egg of fowl, showing area vasculosa 
 
 234. Egg of fish, showing vitelline circulation 
 
 235. Young embryo and its vessels . 
 
 PAGE 
 
 496 
 498 
 499 
 499 
 502 
 503 
 503 
 504 
 505 
 506 
 510 
 512 
 513 
 514 
 517 
 517 
 519 
 519 
 519 
 521 
 522 
 524 
 524 
 527 
 527 
 532 
 53a 
 534 
 537 
 537 
 538 
 539 
 540 
 540 
 541 
 541 
 541 
 547 
 553 
 554 
 554 
 556 
 558 
 558 
 560 
 561 
 562 
 567 
 567 
 568 
 
XXIV 
 
 LIST OF ILLUSTRATIOXS. 
 
 FIG. 
 
 236. Embryo and its vessels, farther advanced 
 
 237. Arterial system, embryonic form 
 
 238. Arterial system, adult form 
 
 239. Early condition of venous system 
 
 240. Venous system, farther advanced 
 
 241. Continued development of venous system 
 
 242. Adult condition of venous system 
 
 243. Early form of hepatic circulation 
 
 244. Hepatic circulation, farther advanced . 
 
 245. Hepatic circulation, during latter part of foetal life 
 
 246. Adult form of hepatic circulation 
 
 247. Foetal heart 
 
 248. Foetal heart 
 
 249. Foetal heart 
 
 250. Foetal heart 
 
 251. Heart of infant 
 
 252. Heart of human foetus, showing Eustachian valve 
 
 253. Circulation through the fcetal heart 
 
 254. Adult circulation through the heart 
 
 PAGE 
 
 569 
 571 
 571 
 573 
 574 
 574 
 575 
 576 
 577 
 577 
 578 
 579 
 579 
 579 
 580 
 580 
 582 
 583 
 586 
 
HUMAN PHYSIOLOGY. 
 
 INTRODUCTION. 
 
 I. Physiology is the study of the phenomena presented by 
 organized bodies, animal and vegetable. 
 
 These phenomena are different from those presented by inorganic 
 substances. They require, for their production, the existence of 
 peculiarly formed animal and vegetable organisms, as well as the 
 presence of various external conditions, such as warmth, light, air, 
 moisture, &c. 
 
 They are accordingly more complicated than the phenomena of 
 the inorganic world, and require for their study, not only a pre- 
 vious acquaintance with the laws of chemistry and physics, but, in 
 addition, a careful examination of other characters which are pecu- 
 liar to them. 
 
 These peculiar phenomena, by which we so readily distinguish 
 living organisms from inanimate substances, are called Vital j^^^eno- 
 mena., or the phenomena of Life. Physiology consequently includes 
 the study of all these phenomena, in whatever order or species of 
 organized body they may originate. 
 
 We find, however, upon examination, that there are certain 
 general characters by which the vital phenomena of vegetables re- 
 semble each other, and by which they are distinguished from the 
 vital phenomena of animals. Thus, vegetables absorb carbonic 
 acid, and exhale oxygen ; animals absorb oxygen, and exhale car- 
 bonic acid. Vegetables nourish themselves by the absorption of 
 unorganized liquids and gases, as water, ammonia, saline solutions, 
 &c. ; animals require for their support animal or vegetable sub- 
 stances as food, such as meat, fruits, milk, &c. Physiology, theu, 
 2 
 
18 INTEODUCTIOX. 
 
 is naturally divided into two parts, viz., Vegetable Physiology, and 
 Animal Physiology. 
 
 Again, the different groups and species of animals, while they 
 resemble each other in their general characters, are distinguished 
 by certain minor diff'erences, both of structure and function, which 
 require a special study. Thus, the physiology of fishes is not ex- 
 actly the same with that of reptiles, nor the physiology of birds 
 with that of c[uadrupeds. Among the warm-blooded quadrupeds, 
 the carnivora absorb more oxygen, in proportion to the carbonic 
 acid exhaled, than the herbivora. Among the herbivorous quad- 
 rupeds, the process of digestion is comparatively simple in the 
 horse, while it is complicated in the ox, and other ruminating ani 
 mals. There is, therefore, a special physiology for every distinct 
 species of animal. 
 
 Human Physiology treats of the vital phenomena of the human 
 species. It is more practically important than the physiology of 
 the lower animals, owing to its connection with human pathology 
 and therapeutics. But it cannot be made the exclusive subject of 
 our study ; for the special physiology of the human body cannot 
 be properly understood without a previous acquaintance with the 
 vital phenomena common to all animals, and to all vegetables; 
 besides which, there are many phj^siological questions that require 
 for their solution experiments and observations, which can onl}^ be 
 made upon the lower animals. 
 
 While the following treatise, therefore, has for its principal sub- 
 ject the study of Human Physiology, this will be illustrated, when- 
 ever it may be required, by what we know in regard to the vital 
 phenomena of vegetables and of the lower animals. 
 
 II. Since Physiology is the study of the active phenomena of 
 livincr bodies, it requires a previous acquaintance with their struc- 
 ture, and with the substances of which they are composed ; that is, 
 with their anatomy. 
 
 Anatomy, again, requires a previous acquaintance with inorganic 
 substances; since some of these inorganic substances enter into the 
 composition of the body. Chloride of sodium, for example, water 
 and phosphate of lime, are component parts of the animal frame, 
 and therefore require to be studied as such by the anatomist. 
 Now these inorganic substances present certain active phenomena, 
 when placed under the requisite external conditions, which are 
 characteristic of them, and by which they may be recognized. 
 
INTRODUCTION. 19 
 
 Thus lime, dissolved in water, if brought into contact with car- 
 bonic acid, alters its condition, and takes part in the formatiou of 
 an insoluble substance, carbonate of lime, which is thrown down 
 as a deposit. A knowledge of such chemical reactions as these is 
 necessary to the anatomist, since it is by them that he is enabled to 
 recognize the inorganic substances, forming a part of the animal 
 body. 
 
 It is important to observe, however, that a knowledge of these 
 reactions is necessary to the anatomist only in order to enable him 
 to judge of the presence or absence of the inorganic substances to 
 which they belong. It is the object of the anatomist to make him- 
 self acquainted with every constituent part of the body. Those 
 parts, therefore, which cannot be recognized by their form and 
 texture, he distinguishes by their chemical reactions. But after- 
 ward, he has no occasion to decompose them further, or to make 
 them enter into new combinations; for he only wishes to know 
 these substances as they exist in the hody, and not as they may exist 
 under other conditions. 
 
 The unorganized substances which exist in the body as compo- 
 nent parts of its structure, such as chloride of sodium, water, phos- 
 phate of lime, &c., are called the proximate principles of the body. 
 Mingled together in certain proportions, they make up the animal 
 fluids, and associated also in a solid form, they constitute the tissues 
 and organs, and in this way make up the entire frame. 
 
 Anatomy makes us acquainted with all these component parts of 
 the body, both solid and fluid. It teaches us the structure of the 
 body in a state of rest; that is, just as it would be after life had 
 suddenly ceased, and before putrefaction had begun. On the other 
 hand. Physiology is a description of the body in a state of activity. 
 It shows us its movements, its growth, its reproduction, and the 
 chemical changes which go on in its interior; and in order to com- 
 prehend these, we must know, beforehand, its entire mechanical, 
 textural, and chemical structure. 
 
 It is evident, therefore, that the description of the proximate prin- 
 ciples^ or the chemical substances entering into the constitution of 
 the body, is, strictly speaking, a part of Anatomy. But there are 
 many reasons why this study is more conveniently pursued in con- 
 nection with Physiology ; for some of the proximate principles are 
 derived directly, as we shall hereafter show, from the external world, 
 and some are formed from the elements of the food in the process 
 of digestion ; while most of them undergo certain changes in the 
 
20 IXTEODUCTION. 
 
 interior of the body, whicli result in the formation of new sub- 
 stances ; all these active phenomena belonging necessarily to the 
 domain of Physiology. 
 
 The description of the proximate principles of animals and vege- 
 tables will therefore be introduced into the following pages. 
 
 The description of the minute structures of the bodj', or Micro- 
 scopic Anatomy, is also so closely connected with some parts of Phy- 
 siology as to make it convenient to speak of them together ; and 
 this will accordingly be done, whenever the nature of the subject 
 may make it desirable. 
 
 III. The study of Physiology, like that of all the other natural 
 sciences, is a study of phenomena, and of phenomena alone. The 
 essential nature of the vital processes, and their ultimate causes, 
 are questions which are beyond the reach of the physiologist, and 
 cannot be determined by the means of investigation which are at 
 his disposal. 
 
 Consequently, all efforts to solve them Avill only serve to mislead 
 the investigator, and to distract his attention from the real subject 
 of examination. Much time has been lost, for example, in discuss- 
 ing the probable reason why menstruation returns, in the human 
 female, at the end of every four weeks. But the observation of 
 nature, which is our only means of scientific investigation, cannot 
 throw any light on this point, but only shows us the fact that men- 
 struation does really recur at the above periods, together with the 
 phenomena which accompany it, and the conditions under which it 
 is hastened or retarded, and increased or diminished, in intensity, 
 duration, &c. If we employ ourselves, consequently, in the discus- 
 sion of the reason above mentioned, we shall only become involved 
 in a network of hypothetical surmises, which can never lead to any 
 definite result. Our time, therefore, will be much more profitabl}^ 
 devoted to the study of the above phenomena, which can be learned 
 from nature, and which constitute, afterward, a permanent acquisi- 
 tion. 
 
 The physiologist, accordingly, confines himself strictly to the 
 study of the vital phenomena themselves, their characters, their 
 frequency, their regularity or irregularity, and the conditions 
 under which they originate. 
 
 When he has discovered that a certain phenomenon always 
 takes place in the presence of certain conditions, he has established 
 what is called a general principle, or a Law of Physiology. 
 
INTRODUCTION. 21 
 
 As, for example, wben lie has ascertained that sensation and 
 motion occupy distinct situations in every part of the nervous 
 system. 
 
 This " Law," however, it must be remembered, is not a discovery 
 by itself, nor does it give him any new information, but is simply 
 the expression, in convenient and comprehensive language, of the 
 facts with which he was already previously acquainted. It is very 
 dangerous, therefore, to make these laws or general principles the 
 subjects of our study instead of the vital phenomena, or to suppose 
 that they have any value, except as the expression of previously 
 ascertained facts. Such a misconception would lead to bad practi- 
 cal results. For if we were to observe a phenomenon in discord- 
 ance with a " law" or " principle," we might be led to neglect or 
 misinterpret the phenomenon, in order to preserve the law. But 
 this would be manifestly incorrect. For the law is not superior to 
 the phenomenon, but, on the contrary, depends upon it, and derives 
 its whole authority from it. Such mistakes, however, have been 
 repeatedly made in Physiology, and have frequently retarded its 
 advance. 
 
 IV. There is only one means by which Physiology can be 
 studied : that is, the observation of nature. Its phenomena cannot 
 be reasoned out by themselves, nor inferred, by logical sequence, 
 from any original principles, nor from any other set of phenomena 
 whatever. 
 
 In Mathematics and Philosophy, on the other hand, certain truths 
 are taken for granted, or perceived by intuition, and the remainder 
 afterward derived from them by a process of reasoning. But in 
 Physiology, as in all the other natural sciences, there is no such 
 starting point, and it is impossible to judge of the character of a 
 phenomenon until after it has been observed. Thus, the only way 
 to learn what action is exerted by nitric acid upon carbonate of 
 soda is to put the two substances together and observe the changes 
 which take place ; for there is nothing in the general characters of 
 these two substances which could guide us in anticipating the result. 
 
 Neither can we infer the truths of Physiology from those of 
 Anatomy, nor the truths of one part of Physiology from those of 
 another part ; but all must be ascertained directly and separately 
 by observation. 
 
 For, although one department of natural science is almost always 
 a necessary preliminary to the study of another, yet the facts of the 
 
22 INTEODUCTION. 
 
 latter can never he in the least degree inferred from those of the former^ 
 hut must he studied hy themselves. 
 
 Thus Chemistry is essential to Anatomy, because certain sub- 
 stances, as we have already shown, belonging to Chemistry, such 
 as chloride of sodium, occur as constituents of the animal body. 
 Chemistry teaches us the composition, reactions, mode of crystal- 
 lization, solubility, &c., of chloride of sodium ; and if we did not 
 know these, we could not extract it, or recognize it when extracted 
 from the body. But, however well we might know the chemistry 
 of this substance, we could never, on that account, irfer its presence 
 in the body or otherwise, nor in what quantities nor in what situa- 
 tions it would present itself. These facts must be ascertained for 
 themselves, by direct investigation, as a part of anatomy proper. 
 
 So, again, the structure of the body in a state of rest, or its ana- 
 tomy, is to be first understood; but its active phenomena or its 
 physiology must then be ascertained by direct observation and 
 experiment. The most intimate knowledge of the minute struc- 
 ture of the muscular and nervous fibres could not teach us any- 
 thing of their physiology. It is only by experiment that we ascer- 
 tain one of them to be contractile, the other sensitive. 
 
 Many of the phenomena of life are chemical in their character, 
 and it is requisite, therefore, that the physiologist know the or- 
 dinary chemical properties of the substances composing the animal 
 frame. But no amount of previous chemical knowledge will 
 enable him to foretell the reactions of any chemical substance in 
 the interior of the body ; because the peculiar conditions, under 
 which it is there placed, modify these reactions, as an elevation or 
 depression of temperature, or other external circumstance, might 
 modify them outside the body. 
 
 We must not, therefore, attempt to deduce the chemical phe- 
 nomena of physiology from any previously established facts, since 
 these are no safe guide ; but must study them by themselves, and 
 depend for our knowledge of them upon direct observation alone. 
 
 V. By the term Vital phenomena^ we mean those phenomena which 
 are manifested in the living body, and which are characteristic of 
 its functions. 
 
 Some of these phenomena are physical or mechanical in their 
 character; as, for example, the play of the articulating surfaces 
 upon each other, the balancing of the spinal column Avith its ap- 
 pendages, the action of the elastic ligaments. Nevertheless, these 
 
INTRODUCTION. 23 
 
 ]>heuomena, tbougli strictly physical in character, are often entirely 
 peculiar and different from those seen elsewhere, because the me- 
 chanism of their production is peculiar in its details. Thus the 
 liuman voice and its modulations are produced in the larynx, in 
 accordance with the general physical laws of sound ; but the 
 arrangement of the elastic and movable vocal chords, with the 
 columns of air above and below, the moist and flexible mucous 
 membrane, and the contractile muscles outside of it, are of such a 
 special character, that the entire apparatus, as well as the sounds 
 produced by it, is peculiar; and its action cannot be properly 
 compared with that of any other known musical instrument. 
 
 In the same manner, the movements of the heart are so com- 
 plicated and remarkable that they cannot be comprehended, even 
 by one who is acquainted with the anatomy of the organ, without 
 a direct examination. This is not because there is anything essen- 
 tially obscure or mysterious in their nature, for they are purely 
 mechanical in character; but because their conditions are so pecu- 
 liar, owing to the tortuous course of the muscular fibres, their ar- 
 rangement in interlacing layers, their attachments and relations, 
 that their combined action produces an effect altogether peculiar, 
 and one which is not similar to anything outside the living body. 
 
 A very large and important class of the vital phenomena are 
 those of a chemical character. It is one of the characteristics of 
 living bodies that a succession of chemical actions, combinations 
 and decompositions, is constantly going on in their interior. It is 
 one of the necessary conditions of the existence of every animal 
 and every vegetable, that it should constantly absorb various sub- 
 stances from without, which undergo different chemical alterations 
 i n its interior, and are finally discharged from it under other forms. 
 If these changes be prevented from taking place, life is immediately 
 extinguished. Thus animals constantly absorb, on the one hand, 
 water, oxygen, salts, albumen, oil, sugar, &c., and give up, on the 
 other hand, to the surrounding media, carbonic acid, water, ammonia, 
 urea, and the like; while between these two extreme points, of ab- 
 sorption and exhalation, there take place a multitude of different 
 transformations which are essential to the continuance of life. 
 
 Some of these chemical actions are the same with those which 
 are seen outside the body ; but most of them are entirely peculiar, 
 and do not take place, and cannot be made to take place, anywhere 
 else. This, again, is not because there is anything particularly 
 mysterious or extraordinary in their nature^ but because the con- 
 
24 INTEODUCTION. 
 
 ditions necessary for their accomplisliment exist in the body, and 
 do not exist elsewhere. All chemical phenomena are liable to be 
 modified by surrounding conditions. Many reactions, for example, 
 which will take place at a high temperature, will not take place at 
 a low temperature, and vice versa. Some will take place in the light, 
 but not in the dark; others will take place in the dark, but not in 
 the light. If a hot concentrated solution of sulphate of soda be 
 allowed to cool in contact with the atmosphere, it crystallizes: 
 covered with a film of oil, it remains fluid. Because a chemical 
 reaction, therefore, takes place under one set of conditions, we can- 
 not be at all sure that it will also take place under others, which 
 are different. 
 
 The chemical conditions of the living body are exceedingly com- 
 plicated. In the animal solids and fluids there are many substances 
 mingled together in varying quantities, which modify or interfere 
 with each other's reactions. New substances are constantly entering 
 by absorption, and old ones leaving by exhalation ; while the circu- 
 lating fluids are constantly passing from one part of the body to 
 another, and coming in contact with different organs of different 
 texture and composition. All these conditions are peculiar, and so 
 modify the chemical actions taking place in the body, that they are 
 unlike those met with anywhere else. 
 
 If starch and iodine be mingled together in a watery solution, 
 they unite with each other, and strike a deep opaque blue color ; 
 but if they be mingled in the blood, no such reaction takes place, 
 because it is prevented by the presence of certain organic substances 
 which interfere with it. 
 
 If dead animal matter be exposed to warmth, air, and moisture, 
 it putrefies ; but if introduced into the living stomach, even after 
 putrefaction has commenced, this process is arrested, because the 
 fluids of the stomach cause the animal substance to undergo a 
 peculiar transformation (digestion), after which the bloodvessels 
 immediately remove it by absorption. There are also certain sub- 
 stances which make their appearance in the living body, both of 
 animals and vegetables, and which cannot be formed elsewhere ; 
 such as fibrin, albumen, casein, pneumic acid, the biliary salts, mor 
 phine, &c. These substances cannot be manufactured artificially, 
 simply because the necessary conditions cannot be imitated. They 
 require for their production the presence of a living organism. 
 
 The chemical phenomena of the living body are, therefore, not 
 different in their nature from any other chemical phenomena ; but 
 
INTRODUCTION. 25 
 
 they are different in tlieir conditions and in tbeir results, and are 
 consequently peculiar and characteristic. 
 
 Another set of vital phenomena are those whicli are manifested 
 in the processes of reproduction and development. They are again 
 entirely distinct from any phenomena which are exhibited by 
 matter not endowed with life. An inorganic substance, even when 
 it has a definite form, as, for example, a crystal of fluor-spar, has 
 no particular relation to any similar form which has preceded, or 
 any other which is to follow it. On the other hand, every animal 
 and every vegetable owes its origin to preceding animals or vege- 
 tables of the same kind ; and the manner in which this production 
 takes place, and the different forms through which the new body 
 successively passes in the course of its development, constitute the 
 phenomena of reproduction. These phenomena are mostly de- 
 pendent on the chemical processes of nutrition and growth, which 
 take place in a particular direction and in a particular manner; but 
 their results, viz., the production of a connected series of different 
 forms, constitute a separate class of phenomena, which cannot be 
 explained in any manner by the preceding, and require, therefore, 
 to be studied by themselves. 
 
 Another set of vital phenomena are those which belong to the 
 nervous system. These, like the processes of reproduction and 
 development, depend on the chemical changes of nutrition and 
 growth. That is to say, if the nutritive processes did not go on in 
 a healthy manner, and keep the nervous system in a healthy condi- 
 tion, the peculiar phenomena which, are characteristic of it could 
 not take place. The nutritive processes are necessary conditions 
 of the nervous phenomena. But there is no other connection 
 between them ; and the nervous phenomena themselves are distinct 
 from all others, both in their nature and in the mode in which they 
 are to be studied. 
 
 A troublesome confusion might arise if we were to neglect the 
 distinction that really exists between these different sets of phe- 
 nomena, and confound them together under the expectation of 
 thereby simplifying our studies. Since this can only be done by 
 overlooking real points of difference, its effect will merely be to 
 introduce erroneous ideas and suggest unfounded similarities, and 
 will therefore inevitably retard our progress instead of advancing it. 
 
 It has been sometimes maintained, for example, that all the vital 
 phenomena, those of the nervous system included, are to be reduced 
 to the chemical chansjes of nutrition, and that these asain are to be 
 
26 INTRODUCTION. 
 
 regarded as not at all different in any respect from the ordinary 
 chemical changes taking place outside the body. This, however, 
 is not only erroneous in theory, but conduces also to a vicious 
 mode of study. For it draws away our attention from the phe- 
 nomena themselves and their real characteristics, and leads us to 
 deduce one set of phenomena from what we know of another; a 
 method which we have already shown to be unsafe and pernicious. 
 It has also been asserted that the phenomena of the nervous 
 system are identical with those of electricity ; for no other reason 
 than that there exist between them certain general resemblances. 
 But when we examine the phenomena in detail, we find that, beside 
 these general resemblances, there are many essential points of dis- 
 similarity, which must be suppressed and kept out of sight in order 
 to sustain the idea of the assumed identity. This assumption is 
 consequently a forced and unnatural one, and the simplicity which 
 it was intended to introduce into our physiological theories is 
 imaginary and deceptive, and is attained only by sacrificing a part 
 of those scientific truths, which are alone the real object of our 
 study. We should avoid, therefore, making auy such unfounded 
 comparisons ; for the theoretical simplicity which results from them 
 does not compensate for the loss of essential scientific details. 
 
 VI. The study of Physiology is naturally divided into three 
 distinct Sections : — 
 
 The first of these includes everything which relates to the Nutri- 
 tion of the body in its widest sense. It comprises the history of 
 the proximate principles, their source, the manner of their produc- 
 tion, the proportions in which they exist in different kinds of food 
 and drink, the processes of digestion and absorption, and the con- 
 stitution of the circulating fluids; then the physical phenomena of 
 the circulation and the forces by which it is accomplished ; the 
 changes which the blood undergoes in different parts of the body ; 
 all the phenomena, both physical and chemical, of respiration; those 
 of secretion and excretion, and the character and destination of the 
 secreted and excreted fluids. All these processes have reference to 
 a common object, viz., the preservation of the internal structure 
 and healthy organization of the individual. With certain modifi- 
 cations, they take place in vegetables as well as in animals, and are 
 consequently known by the name of the vegetative functions. 
 
 The Second Section, in the natural order of study, is devoted to 
 the phenomena of the Nervous System. These phenomena are 
 
INTRODUCTION. 27 
 
 Dot exhibited by vegetables, but belong exclusively to animal or- 
 ganizations. They bring the animal body into relation with the 
 external world, and preserve it from external dangers, through the 
 means of sensation, movement, consciousness, and volition. They 
 are more particularly distinguished by the name of the animal 
 functions. 
 
 Lastly comes the study of the entire process of Reproduction. 
 Its phenomena, again, with certain modifications, are met with in 
 both animals and vegetables ; and might, therefore, with some pro- 
 priety, be included under the head of vegetative functions. But 
 their distinguishing peculiarity is, that they have for their object 
 the production of new organisms, which take the place of the old 
 and remain after they have disappeared. These phenomena do 
 not, therefore, relate to the preservation of the individual, but to 
 that of the species; and any study which concerns the species 
 comes properly after we have finished everything relating to the 
 individual. 
 
SECTIOI( I. 
 NUTRITION. 
 
 CHAPTER I. 
 
 PROXIMATE PRINCIPLES IN GENERAL. 
 
 The study of Nuteition begins naturally with tliat of the 2^roxi- 
 mate princijjies, or the substances entering into the composition of 
 the different parts of the body, and the different kinds of food. In 
 examining the body, the anatomist finds that it is composed, first, 
 of various parts, which are easily recognized by the eye, and which 
 occupy distinct situations. In the case of the human body, for 
 example, a division is easily made of the entire frame into the head, 
 the neck, the trunk, and extremities. Each of these regions, again, 
 is found, on examination, to contain several distinct parts, or 
 "organs," which require to be separated from each other by dissec- 
 tion, and which are distinguished by their form, color, texture, and 
 consistency. In a single limb, for example, every bone and every 
 muscle constitutes a distinct organ. In the trunk, we have the 
 heart, the lungs, the liver, spleen, kidneys, spinal cord, &c., each of 
 which is also a distinct organ. When a number of organs, differing 
 in size and form, but similar in texture, are found scattered through- 
 out the entire frame, or a large portion of it, they form a connected 
 set or order of parts, which is called a " system." Thus, all the 
 muscles taken together constitute the muscular system; all the 
 bones, the osseous system; all the arteries, the arterial system. 
 Several entirely different organs may also be connected with each 
 other, so that their associated actions may tend to accomplish a 
 single object, and they then form an " apparatus." Thus the heart, 
 arteries, capillaries, and veins, together, form the circulatory appa- 
 ratus; the stomach, liver, pancreas, intestine, &c., the digestive 
 apparatus. Every organ, again, on microscopic examination, is 
 
30 PEOXIMATE PRIXCIPLES IX GEXEPvAL. 
 
 seen to be made up of minute bodies, of definite size and figure, 
 which, are so small as to be invisible to the naked eye, and which, 
 after separation from each other, cannot be further subdivided with- 
 out destroying their organization. They are, therefore, called "ana- 
 tomical elements." Thus, in the liver, there are hepatic cells, capil- 
 lary bloodvessels, the fibres of Glisson's capsule, and the ultimate 
 filaments of the hepatic nerves. Lastly, two or more kinds of ana- 
 tomical elements, interwoven with each other in a particular manner, 
 form a "tissue." Adipose vesicles, with capillaries and nerve tubes, 
 form adipose tissue. White fibres and elastic fibres, with capillaries 
 and nerve tubes, form areolar tissue. Thus the solid parts of the 
 entire body are made up of anatomical elements, tissues, organs, 
 systems, and apparatuses. Every organized frame, and even every 
 apparatus, every organ, and every tissue, is made up of different 
 parts, variously interwoven and connected with each other, and it 
 is this character which constitutes its organization. 
 
 But besides the above solid forms, there are also certain fluids, 
 which are constantly present in various parts of the body, and which, 
 from their peculiar constitution, are termed "animal fluids." These 
 fluids are just as much an essential part of the body as the solids. 
 The blood and the lymph, for example, the pericardial and synovial 
 fluids, the saliva, which always exists more or less abundantly in 
 the ducts of the parotid gland, the bile in the biliary ducts and the 
 gall-bladder: all these go to make up the entire body, and are quite 
 as necessary to its structure as the muscles or the nerves. Now, if 
 these fluids be examined, they are found to be made up of many 
 different substances, which are mingled together in certain propor- 
 tions ; these proportions being constantly maintained at or about 
 the same standard by the natural processes of nutrition. Such a 
 fluid is termed an organized fluid. It is organized by virtue of the 
 numerous ingredients which enter into its composition, and the 
 regular proportions in which these ingredients are maintained. 
 Thus, in the plasma of the blood, we have albumen, fibrin, water, 
 chlorides, carbonates, phosphates, &c. In the urine, we find water, 
 urea, urate of soda, creatine, creatinine, coloring matter, salts, &c. 
 These substances, which are mingled together so as to make up, in 
 each instance, by their intimate union, a homogeneous liquid, are 
 called the proximate peikciples of the animal fluid. 
 
 In the solids, however, even in those parts which are apparently 
 homogeneous, there is the same mixture of different ingredients. 
 In the hard substance of bone, for example, there is, first, water, 
 
TKOXIMATE PRINCIPLES IN GENERAL, 31 
 
 •\vliich may be expelled bj evaporation; second, phosphate and car- 
 bonate of lime, which may be extracted by the proper solvents; 
 third, a peculiar animal matter, with which these calcareous salts 
 are in union ; and fourth, various other saline substances, in special 
 proportions. In the muscular tissue, there is chloride of potassium, 
 lactic acid, water, salts, albumen, and an animal matter termed mus- 
 culine. The difference in consistenc}^ between the solids does not, 
 therefore, indicate any radical difference in their constitution. Both 
 solids and fluids are equallj' made up of proximate principles, min- 
 gled together in various proportions. 
 
 It is important to understand, however, exactly what are proxi- 
 mate principles, and what are not such ; for since these principles 
 are extracted from the animal solids and fluids, and separated from 
 each other by the help of certain chemical manipulations, such as 
 evaporation, solution, crystallization, and the like, it might be sup- 
 posed that every substance which could be extracted from an organ- 
 ized solid or fluid, by chemical means, should be considered as a 
 proximate principle. That, however, is not the case. A proximate 
 principle is properly defined to be any substance, luhether simple or 
 compound, chemically speaking, ichich exists, under its own form, in the 
 animal solid or fluid, and which can be extracted by means which do 
 not alter or destroy its chemical properties. Phosphate of lime, for 
 example, is a proximate principle of bone, but phosphoric acid is 
 not so, since it does not exist as such in the bony tissue, but is pro- 
 duced only by the decomposition of the calcareous salt ; still less 
 phosphorus, which is obtained only by the decomposition of the 
 phosphoric acid. 
 
 Proximate principles may, in fact, be said to exist in all solids or 
 fluids of mixed composition, and may be extracted from them by 
 the same means as in the case of the animal tissues or secretions. 
 Thus, in a watery solution of sugar, we have two pi'oximate princi- 
 ples, viz : first, the water, and second, the sugar. The water may 
 be separated by evaporation and condensation, after which the 
 sugar remains behind, in a crystalline form. These two substances 
 have, therefore, been simply separated from each other by the pro- 
 cess of evaporation. They have not been decomposed, nor their 
 chemical properties altered. On the other hand, the oxygen and 
 hydrogen of the water were not proximate principles of the original 
 solution, and did not exist in it under their own forms, but only in 
 a state of combination; forming, in this condition, a fluid substance 
 (water), endowed with sensible properties entirely different from 
 
32 PROXIMATE PRINCIPLES IN GENERAL. 
 
 theirs. If we wisli to ascertain, accordingly, the nature and proper- 
 ties of a saccharine solution, it will afford us but little satisfaction to 
 extract its ultimate chemical elements; for its nature and properties 
 depend not so much on the presence in it of the ultimate elements, 
 oxygen, hydrogen, and carbon, as on the particular forms of com- 
 bination, viz., water and sugar, under which they are present. 
 
 It is very essential, therefore, that in extracting the proximate 
 principles from the animal body, only such means should be adopted 
 as will isolate the substances already existing in the tissues and 
 fluids, without decomposing them, or altering their nature. A 
 neglect of this rule has been productive of much injury in the pur- 
 suit of organic chemistry; for chemists, in subjecting the animal 
 tissues to the action of acids and alkalies, of prolonged boiling, or 
 of too intense heat, have often obtained, at the end of the analj^sis, 
 many substances which were erroneously described as proximate 
 principles, while they were only the remains of an altered and dis- 
 organized material. Thus, the fibrous tissues, if boiled steadily for 
 thirty- six hours, dissolve, for the most part, at the end of that time, 
 in the boiling water ; and on cooling the whole solution solidifies 
 into a homogeneous, jelly-like substance, which has received the 
 name of gelatine. But this gelatine does not really exist in. the body 
 as a proximate principle, since the fibrous tissue which produces it 
 is not at first soluble, even in boiling water, and its ingredients 
 become altered and converted into a gelatinous matter only by pro- 
 longed ebullition. So, again, an animal substance containing ace- 
 tates or lactates of soda or lime will, upon incineration in the open 
 air, yield carbonates of the same bases, the organic acid having been 
 destroyed, and replaced by carbonic acid ; or sulphur and phospho- 
 rus, in the animal tissue, may be converted by the same means into 
 sulphuric and phosphoric acids, which, decomposing the alkaline 
 carbonates, become sulphates and phosphates. In either case, the 
 analysis of the tissues, so conducted, will be a deceptive one, and 
 useless for all anatomical and physiological purposes, because its 
 real ingredients have been decomposed, and replaced by others, in 
 the process of manipulation. 
 
 It is in this way that different chemists, operating upon the same 
 animal solid or fluid, by following different plans of analysis, have 
 obtained different results; enumerating as ingredients of the body 
 many artificially formed substances, which are not, in reality, 
 proximate principles, thereby introducing much confusion into phy- 
 siological chemistry. 
 
PEOXIMATE PRINCIPLES IN GENERAL. 33 
 
 It is to be kept constantly in view, in the examination of an ani- 
 mal tissue or fluid, that the object of the operation is simply the 
 separation of its ingredients from each other, and not their decomposi- 
 tion or ultimate analysis. Only the simplest forms of chemical 
 manipulation should, therefore, be employed. The substance to be 
 examined should first be subjected to evaporation, in order to 
 extract and estimate its water. This evaporation must be conducted 
 at a heat not above 212° F., since a higher temperature would de- 
 stroy or alter some of the animal ingredients. Then, from the dried 
 residue, chloride of sodium, alkaline sulphates, carbonates, and phos- 
 phates may be extracted with water. Coloring matters may be 
 separated by alcohol. Oils may be dissolved out by ether, &c. &c. 
 When a chemical decomposition is unavoidable, it must be kept in 
 sight and afterward corrected. Thus the glyko-cholate of soda of 
 the bile is separated from certain other ingredients by precipitating 
 it with acetate of lead, forming glyko-cholate of lead ; but this is 
 afterward decomposed, in its turn, by carbonate of soda, reproduc- 
 ing the original glyko-cholate of soda. Sometimes it is impossible 
 to extract a proximate principle in an entirely unaltered form. 
 Thus the fibrin of the blood can be separated only by allowing it 
 to coagulate ; and once coagulated, it is permanently altered, and 
 can no longer present all its original characters of fluidity, &c., as 
 it existed beforehand in the blood. In such instances as this, we 
 can only make allowance for an unavoidable difficulty, and be care- 
 ful that the substance suffers no further alteration. By bearing in 
 mind the above considerations, we may form a tolerably correct 
 estimate of the nature and quantity of all of the proximate princi- 
 ples existing in the substance under examination. 
 
 The manner in which the proximate principles are associated 
 together, so as to form the animal tissues, is deserving of notice. 
 In every animal solid and fluid, there is a considerable number of 
 proximate principles, which are present in certain proportions, and 
 which are so united with each other that the mixture presents a 
 homogeneous appearance. But this union is of a complicated cha- 
 racter ; and the presence of each ingredient depends, to a certain 
 extent, upon that of the others. Some of them, such as the alkaline 
 carbonates and phosphates, are in solution directly in the water. 
 Some, which are insoluble in water, are held in solution by the 
 presence of other soluble substances. Thus, phosphate of lime is 
 held in solution in the urine by the bi-phosphate of soda. In 
 the blood, it is dissolved by the albumen, which is itself fluid by 
 3 
 
34 PEOXIMATE PRINCIPLES IN GENEEAL. 
 
 union with the water. The same substance may be fluid in one 
 part of the body, and solid in another part. Thus in the blood 
 and secretions the water is fluid, and holds in solution other sub- 
 stances, both animal and mineral, while in the bones and cartilages 
 it is solid — not crystallized, as in the case of ice or of saline sub- 
 stances which contain water of crystallization, but amorphous and 
 solid, by the fact of its intimate union with the animal and saline 
 ingredients, which are abundant in. quantity, and which are them- 
 selves present in the solid form. Again, the phosphate of lime in 
 the blood is fluid by solution in the albumen; but in the bones it 
 forms a solid substance with the animal matter of the osseous 
 tissue; and yet the union of the two is as intimate and. homo- 
 geneous in the bones as in the blood. A proximate principle, 
 therefore, never exists alone in any part of the body, but is always 
 intimately associated with a number of others by a kind of homo- 
 geneous mixture or solution. 
 
 Every animal tissue and fluid contains a number of proximate 
 principles which are present, as we have already mentioned, in 
 certain characteristic proportions. Thus, water is present in very 
 large quantity in the perspiration and the saliva, but in very small 
 quantity in the bones and teeth. Chloride of sodium is compara- 
 tively abundant in the blood and deficient in the muscles. On the 
 other hand, chloride of potassium is more abundant in the muscles, 
 less so in the blood. But these proportions, it is important to ob- 
 serve, are nowhere absolute or invariable. There is a great differ- 
 ence in this respect between the chemical composition of an inor- 
 ganic substance and the anatomical constitution of an animal flaid. 
 The former is always constant and definite; the latter is always 
 subject to certain variations. Thus, water is always composed of 
 exactly the same relative quantities of oxygen and hydrogen ; and 
 if these proportions be altered in the least, it thereby ceases to be 
 water, and is converted into some other substance. But in the 
 urine, the proportions of water, urea, urate of soda, phosphates, &c., 
 vary within certain limits in different individuals, and even in the 
 same individual, from one hour to another. This variation, which 
 is almost constantly taking place,, within the limits of health, is 
 characteristic of all the animal solids and fluids ; for they are com- 
 posed of different ingredients which are supplied by absorption or 
 formed in the interior, and which are constantly given up again, 
 under the same or different forms, to the surrounding media by the 
 unceasing activity of the vital processes. Every variation, then, in 
 
PROXIMATE PRINCIPLES IN GENERAL. 35 
 
 the general condition of the body, as a whole, is accompanied by 
 a corresponding variation, more or less pronounced, in the consti- 
 tution of its different parts. This constitution is consequently of 
 a very different character from the chemical constitution of an 
 oxide or a salt. Whenever, therefore, we meet with the quantita- 
 tive analysis of an animal fluid, in which the relative quantity of 
 its different ingredients is represented in numbers, we must under- 
 stand that such an analysis is always approximative, and not abso- 
 lute. 
 
 The proximate principles are naturally divided into three differ- 
 ent classes. 
 
 The first of these classes comprises all the proximate principles 
 which are purely inorganic in their nature. These principles are 
 derived mostly from the exterior. They are found everywhere, in 
 unorganized as well as in organized bodies; and they present them- 
 selves under the same forms and with the same properties in the 
 interior of the animal frame as elsewhere. They are crystallizable, 
 and have a definite chemical composition. They comprise sucb 
 substances as water, chloride of sodium, carbonate and phosphate 
 of lime, &c. 
 
 The second class of proximate principles is known as crystal- 
 lizable SUBSTANCES OF ORGANIC ORIGIN. This is the name given 
 to them by Robin and Yerdeil,' whose classification of the proxi- 
 mate principles is the best which, has yet been offered. They are 
 crystallizable, as their name indicates, and have a definite chemical 
 composition. They are said to be of "organic origin," because they 
 first make their appearance in the interior of organized bodies, and 
 are not found in external nature as the ingredients of inorganic 
 substances. Such are the different kinds of sugar, oil, and starch. 
 
 The third class comprises a very extensive and important order 
 of proximate principles, which go by the name of the Organic 
 Substances proper. They are sometimes known as "albuminoid" 
 substances or "protein compounds." The name organic substances 
 is given to them in consequence of the striking difference which 
 exists between them and all the other ingredients of the body. The 
 substances of the second class differ from those of the first by their 
 
 ' Chimie Anatomique et Physiologique. Paris, 1853. 
 
36 PROXIMATE PRINCIPLES IN GENERAL. 
 
 exclusively organic origin, but they resemble the latter in their crys- 
 tallizability and their definite chemical composition; in consequence 
 of which their chemical investigation may be pursued in nearly 
 the same manner, and their chemical changes expressed in nearly 
 the same terms. But the proximate principles of the third class 
 are in every respect peculiar. They have an exclusively organic 
 origin ; not being found except as ingredients of living or recently 
 dead animals or vegetables. They have not a definite chemical 
 composition, and are consequently not crystallizable; and the forms 
 which they present, and the chemical changes which they undergo 
 in the body, are such as cannot be expressed by ordinary chemical 
 phraseology. This class includes such substances as albumen, 
 fibrin, casein, &c. 
 
PROXIMATE PRINCIPLES OF THE FIRST CLASS. 37 
 
 CHAPTER II. 
 
 PROXIMATE PRINCIPLES OF THE FIRST CLASS. 
 
 The proximate principles of the first class, or those of an inor- 
 ganic nature, are very numerous. Their most prominent characters 
 have already been stated. They are all crystallizable, and have a 
 definite chemical composition. They are met with extensively in 
 the inorganic world, and form a large part of the crust of the earth. 
 They occur abundantly in the different kinds of food and drink ; 
 and are necessary ingredients of the food, since they are necessary 
 ingredients of the animal frame. Some of them are found universally 
 in all parts of the body, others are met with only in particular 
 regions; but there are hardly any which are not present at the 
 same time in more than one animal solid or fluid. The following 
 are the most prominent of them, arranged in the order of their re- 
 spective importance. 
 
 1. Water. — Water is universally present in all the tissues and 
 fluids of the body. It is abundant in the blood and secretions, 
 where its presence is indispensable in order to give them the fluid- 
 ity which is necessary to the performance of their functions ; for 
 it is by the blood and secretions that new substances are intro- 
 duced into the body, and old ingredients discharged. And it is 
 a necessary condition both of the introduction and discharge of 
 substances naturally solid, that they assume, for the time being, a 
 fluid form ; water is therefore an essential ingredient of the fluids, 
 for it holds their solid materials in solution, and enables them to 
 pass and repass through the animal frame. 
 
 But water is an ingredient also of the solids. For if we take a 
 muscle or a cartilage, and expose it to a gentle heat in dry air, it 
 loses water by evaporation, diminishes in size and weight, and be- 
 comes dense and stiff. Even the bones and teeth lose water by 
 evaporation in this way, though in smaller quantity. In all these 
 solid and semi-solid tissues, the water which they contain is useful 
 
38 
 
 PEOXIMATE PRINCIPLES OF THE FIRST CLASS. 
 
 37 
 
 Bile . 
 
 . 880 
 
 100 
 
 Milk 
 
 . 887 
 
 130 
 
 Pancreatic juice 
 
 . 900 
 
 550 
 
 Urine 
 
 . 936 
 
 750 
 
 Lymph. 
 
 . 960 
 
 768 
 
 Gastric juice 
 
 . 975 
 
 789 
 
 Perspiration 
 
 . 986 
 
 795 
 
 Saliva 
 
 . 995 
 
 805 
 
 
 
 bj giving them the special consistency which is characteristic of 
 them, and which would be lost without it. Thus a tendon, in its 
 natural condition, is white, glistening, and opaque ; and though very 
 strong, perfectly flexible. If its water be expelled by evaporation 
 it becomes yellowish in color, shrivelled, semi-transparent, inflexi- 
 ble, and totally unfit for performing its mechanical functions. The 
 same thing is true of the skin, muscles, cartilages, &c. 
 
 The following is a list, compiled by Eobin and Yerdeil from 
 various observers, showing the proportion of water per thousand 
 parts, in different solids and fluids: — 
 
 Quantity of Water in 1,000 parts in 
 Epidermis 
 Teeth 
 Bones 
 Cartilage 
 Muscles . 
 Ligaments 
 Brain 
 Blood 
 Synovial fluid 
 
 According to the best calculations, water constitutes, in the 
 human subject, between two-thirds and three-quarters of the entire 
 weight of the body. 
 
 The water which thus forms a part of the animal frame is derived 
 from without. It is taken in the different kinds of drink, and also 
 forms an abundant ingredient in the various articles of food. For 
 no articles of food are taken in an absolutely dry state, but all 
 contain a larger or smaller quantity of water, which may readily 
 be expelled, by evaporation. The quantity of water, therefore, 
 which is daily taken into the system, cannot be ascertained in any 
 case by simply measuring the quantity of drink, but its proportion 
 in the solid food, taken at the same time, must also be determined 
 by experiment, and this ascertained quantity added to that which 
 is taken in with the fluids. The entire quantity of water so intro- 
 duced during twenty-four hours varies according to the researches 
 of M. Barral' from 3f to 4J pounds. 
 
 After forming a part of the animal solids and fluids, and taking 
 part in the various physical and chemical processes of the body, the 
 water is again discharged ; for its presence in the body, like that 
 of all the other proximate principles, is not permanent, but only 
 
 ' In Robin and Verdeil, vol. ii. p. 139. 
 
CHLORIDE OF SODIUM. 39 
 
 temporary. After being taken in with the food and drink, it is 
 associated with other principles in the fluids and solids, passing 
 from the intestine to the blood and from the blood to the tissues 
 and secretions. It afterwards makes its exit from the body, from 
 which it is discharged by four different passages, viz., in a liquid 
 form with the urine and the feces, and in a gaseous form with the 
 breath and the perspiration. Of all the water which is expelled in 
 this way, about 48 per cent, is discharged Avith the urine and feces, ^ 
 and about 52 per cent, by the lungs and skin. This estimate, how- 
 ever, is an average, calculated from the observations of different 
 authors upon different individuals. The absolute and relative 
 amount of water discharged, both in a liquid and gaseous form, 
 varies according to circumstances. There is particularly a com- 
 pensating action in this respect between the kidneys and the skin, 
 so that when the cutaneous perspiration is very abundant the urine 
 is less so, and vice versa. The quantity of water exhaled from the 
 lungs varies also with the state of the pulmonary circulation, and 
 with the temperature and dryness of the atmosphere. The water 
 is not discharged at any time in a state of purity, but is mingled in 
 the urine and feces with saline substances which it holds in solution, 
 and in the cutaneous and pulmonary exhalations with animal vapors 
 and odoriferous substances of various kinds. In the perspiration it 
 is also mingled with saline substances, which it leaves behind on 
 evaporation. 
 
 2. Chloeide of Sodium. — This substance is found, like water, 
 throughout the different tissues and fluids of the body. The only 
 exception to this is perhaps the enamel of the teeth, where it has 
 not yet been discovered. Its presence is important in the body, as 
 regulating the phenomena of endosmosis and exosmosis in different 
 parts of the frame. For we know that a solution of common salt 
 passes through animal membranes much less readily than pure 
 water; and tissues which have been desiccated will absorb pure 
 water more abundantly than a saline solution. It must not be sup- 
 posed, however, that the presence or absence of chloride of sodium, 
 or its varying quantity in the animal fluids, is the only condition 
 which regulates their transudation through the animal membranes. 
 The manner in which endosmosis and exosmosis take place in the 
 animal frame depends upon the relative quantity of all the ingre- 
 
 ' Op. cit., vol. ii. pp. 143 and 145. 
 
40 
 
 PROXIilATE PEIXCIPLES OF THE FIRST CLASS. 
 
 clients of the fluids, as well as on the constitution of the solids them- 
 selves; and the chloride of sodium, as one ingredient among many, 
 influences these phenomena to a great extent, though it does not 
 regulate them exclusively. 
 
 It exerts also an important influence on the solution of various 
 other ingredients, with which it is associated. Thus, in the blood 
 it increases the solubility of the albumen, and perhaps also of the 
 earthy phosphates. The blood-globules, again, which become dis- 
 integrated and dissolved in a solution of pure albumen, are main- 
 tained in a state of integrity by the presence of a small quantity of 
 chloride of sodium. 
 
 It exists in the following proportions in several of the solids and 
 fluids :^ — 
 
 QCA>'TITY OF ChLOEIDE OF SoiJirjI IS 1.000 PAETS !>' THE 
 
 Muscles . 
 
 2 
 
 Bile 
 
 3.5 
 
 Bones 
 
 2.5 
 
 Blood . 
 
 4.5 
 
 Milk 
 
 1 
 
 Mucus . 
 
 6 
 
 Saliva . 
 
 1.5 
 
 Aqueous humor 
 
 '. 11 
 
 Urine 
 
 3 
 
 Vitreous hurnor 
 
 . 14 
 
 In the blood it is rather more abundant than all the other saline 
 ingredients taken together. 
 
 Since chloride of sodium is so universally present in all parts of 
 the body, it is an important ingredient also of the food. It occurs, 
 of course, in all animal food, in the quantities in which it naturally 
 exists in the corresponding tissues; and in vegetable food also, 
 though in smaller amount. Its proportion in muscular flesh, 
 however, is much less than in the blood and other fluids. Conse- 
 quently, it is not supplied in sufficient quantity as an ingredient of 
 animal and vegetable food, but is taken also by itself as a condi- 
 ment. There is no other substance so universally used by all races 
 and conditions of men, as an addition to the food, as chloride of 
 sodium. This custom does not simply depend on a fancy for grati- 
 fying the palate, but is based upon an instinctive desire for a sub- 
 stance which is necessary to the proper constitution of the tissues 
 and fluids. Even the herbivorous animals are greedy of it, and if 
 freely supplied with it, are kept in a much better condition than 
 when deprived of its use. 
 
 The importance of chloride of sodium in this respect has been 
 well demonstrated by Boussingault, in his experiments on the 
 fattening of animals. These observations were made upon six 
 
 ' Robin and Verdeil. 
 
CHLOKIDE OF SODIUM. 41 
 
 bullocks, selected, as nearly as possible, of the same age and vigor, 
 and subjected to comparative experiment. They were all supplied 
 with an abundance of nutritious food ; but three of them (lot No. 
 1) received also a little over 500 grains of salt each per day. The 
 remaining three (lot No, 2) received no salt, but in other respects 
 were treated like the first. The result of these experiments is given 
 by Boussingault as follows : — ' 
 
 "Though salt administered with the food has but little effect in 
 increasing the size of the animal, it appears to exert a favorable 
 influence upon his qualities and general aspect. Until the end of 
 March (the experiment began in October) the two lots experimented 
 on did not present any marked difference in their appearance ; but 
 in the course of the following April, this difference became quite 
 manifest, even to an unpractised eye. The lot No. 2 had then been 
 without salt for six months. In the animals of both lots the skin 
 had a fine and substantial texture, easily stretched and separated 
 from the ribs; but the hair, which was tarnished and disordered in 
 the bullocks of the second lot, was smooth and glistening in those 
 of the first. As the experiment went on, these characters became 
 more marked ; and at the beginning of October the animals of lot 
 No. 2, after going without salt for an entire year, presented a rough 
 and tangled hide, with patches here and there where the skin was 
 entirely uncovered. The bullocks of lot No. 1 retained, on the 
 contrary, the ordinary aspect of stall-fed animals. Their vivacity 
 and their frequent attempts at mounting contrasted strongly with 
 the dull and unexcitable aspect presented by the others. No doubt, 
 the first lot would have commanded a higher price in the market 
 than the second." 
 
 Chloride of sodium acts also in a favorable manner by exciting 
 the digestive fluids, and assisting in this way the solution of the 
 food. For food which is tasteless, however nutritious it may be in 
 other respects, is taken with reluctance and digested with difficulty; 
 while the attractive flavor which is developed by cooking and by 
 the addition of salt and other condiments in proper proportion 
 excites the secretion of the saliva and gastric juice, and facilitates 
 consequently the whole process of digestion. The chloride of 
 sodium is then taken up by absorption from the intestine, and is 
 deposited in various quantities in different parts of the body. 
 It is discharged with the urine, mucus, cutaneous perspiration, 
 
 ' Chimie Agricole, p. 271. Paris, 1854. 
 
42 PEOXIMATE PRINCIPLES OF THE FIRST CLASS, 
 
 &c., in solution in tlie water of these fluids. According to the esti- 
 mates of M. Barral/ a small quantity of chloride of sodium dis 
 appears in the body; since he finds by accurate comparison that all 
 the salt introduced with the food is not to be found in the excreted 
 fluids, but that about one-fifth of it remains unaccounted for. This 
 portion is supposed to undergo a double decomposition in the blood 
 with phosphate of potass, forming chloride of potassium and phos- 
 phate of soda. By far the greater part of the chloride of sodium, 
 however, escapes under its own form with the secretions. 
 
 3, Chloride of Potassium. — This substance is found in the 
 muscles, the blood, the milk, the urine, and various other fluids 
 and tissues of the body. It is not so universally present as chlo- 
 ride of sodium, and not so important as a proximate principle. 
 In some parts of the body it is more abundant than the latter 
 salt, in others less so. Thus, in the blood there is more chloride 
 of sodium than chloride of potassium, but in the muscles there is 
 more chloride of potassium than chloride of sodium. This sub- 
 stance is always in a fluid form, by its ready solubility in water, 
 and is easily separated by lixiviation, It is introduced mostly with 
 the food, but is probably formed partly in the interior of the body 
 from chloride of sodium by double decomposition, as already men- 
 tioned. It is discharged with the mucus, the saliva, and the urine. 
 
 4. Phosphate of Lime. — This is perhaps the most important 
 of the mineral ingredients of the body next to chloride of sodium. 
 It is met with universally, in every tissue and every fluid. Its 
 quantity, however, varies very much in different parts, as will be 
 seen by the following list: — 
 
 Quantity of Phosphate of Lime in 1,000 parts in the 
 Enamel of the teeth . . 885 Muscles . . . .2.5 
 
 Dentine . . . .643 Blood . . . .0.3 
 
 Bones .... 550 Gastric juice . • • 0.4 
 
 Cartilages ... 40 
 
 It occurs also under different physical conditions. In the bones, 
 teeth, and cartilages it is solid, and gives to these tissues the resist- 
 ance and solidity which are characteristic of them. The calcareous 
 salt is not, however, in these instances, simply deposited mechani- 
 cally in the substance of the bone or cartilage as a granular powder, 
 but is intimately united with the animal matter of the tissues, like 
 
 ' In Robin and Verdeil, op. cit., vol. ii. p. 193. 
 
PHOSPHATE OF LIME. 
 
 43 
 
 a coloring matter in colored glass, so as to present a more ov less 
 homogeneous appearance. It can, however, be readily dissolved 
 out by maceration in dilute muriatic acid, leaving behind the 
 animal substance, which still retains the original form of the bone 
 or cartilage. It is not, therefore, united with the animal matter so 
 as to lose its identity and form a new chemical substance, as where 
 an acid combines with an alkali to form a salt, but in the same 
 manner as salt unites with water in a saline solution, both sub- 
 stances retaining their original character and composition, but so 
 intimately associated that they cannot be separated by mechanical 
 means. 
 
 In the blood, phosphate of lime is in a liquid form, notwithstand- 
 ing its insolubility in water and in alkaline fluids, being held in 
 solution by the albuminous matters of the circulating fluid. In the 
 urine, it is retained in solution by the bi-phosphate of soda. 
 
 In all the solid tissues it is useful by giving to them their proper 
 consistence and solidity. For example, in the enamel of the teeth, 
 the hardest tissue of the body, it predominates very much over 
 the animal matter, and is present in greater abun- 
 dance there than in any other part of the frame. 
 In the dentine, a softer tissue, it is in somewhat 
 smaller quantity, and in the bones smaller still ; 
 though in the bones it continues to form more 
 than one-half the entire mass of the osseous sub- 
 stance. The importance of phosphate of lime in 
 communicating to bones their natural stiffness and 
 consistency may be readily shown by the altera- 
 tion which they suffer from its removal. If a long 
 bone be macerated in dilute muriatic acid, the 
 earthy salt, as already mentioned, is entirely dis- 
 solved out, when the bone loses its rigidity, and 
 may be bent or twisted in any direction without 
 breaking. (Fig. 1.) 
 
 Whenever the nutrition of the bone during life 
 is interfered with from any pathological cause, so 
 that its phosphate of lime becomes deficient in 
 amount, a softening of the osseous tissue is the 
 consequence, by which the bones yield to external 
 pressure, and become more or less distorted. (Osteo- 
 malakia.) 
 
 After forming, for a time, a part of the tissues and fluids, the 
 
 PlBtTLA TIED IN A 
 
 KNOT, after macera- 
 tion in a dilute acid. 
 (From a specimen in 
 tlie museum of the 
 College of Physicians 
 and Surgeons.) 
 
44 PEOXIMATE PEIN'CIPLES OP THE FIEST CLASS. 
 
 phosphate of lime is discharged from the body by the urine, the 
 perspiration, mucus, &c. Much the larger portion is discharged by 
 the urine. A small quantity also occurs in the feces, but that is pro- 
 bably only the superfluous residue of what is taken in with the food. 
 
 5. Caebonate of Lime. — Carbonate of lime is to be found in 
 the bones, and sometimes in the urine. The concretions of the 
 internal ear are almost entirely formed of it. It very probably 
 occurs also in the blood, teeth, cartilages, and sebaceous matter; 
 but its presence here is not quite certain, since it may have been 
 produced from the lactate, or other organic combination, by the 
 process of incineration. In the bones, it is in much smaller quan- 
 tity than the phosphate. Its solubility in the blood and the urine 
 13 accounted for by the presence of free carbonic acid, and also of 
 chloride of potassium, both of which substances exert a soluble 
 action on carbonate of lime. 
 
 6. Caeboxate of Soda. — This substance exists in the bones, 
 blood, saliva, lymph, and urine. As it is readily soluble in water, 
 it naturally assumes the liquid form in the animal fluids. It is 
 important principally as giving to the blood its alkalescent reaction, 
 by which the solution of the albumen is facilitated, and various 
 other chemico-physiological processes in the blood accomplished. 
 The alkalescence of the blood is, in fact, necessary to life ; for it is 
 found that, in the living animal, if a mineral acid be gradually 
 injected into the blood, so dilute as not to coagulate the albumen, 
 death takes place before its alkaline reaction has been completely 
 neutralized.^ 
 
 The carbonate of soda of the blood is partly introduced as such 
 with the food ; but the greater part of it is formed within the body 
 by the decomposition of other salts, introduced with certain fruits 
 and vegetables. These fruits and vegetables, such as apples, 
 cherries, grapes, potatoes, &c., contain malates, tartrates, and 
 citrates of soda and potass. Now, it has been often noticed that, 
 after the use of acescent fruits and vegetables containing the above 
 salts, the urine becomes alkaline in reaction from the presence of 
 the alkaline carbonates. Lehmann^ found, by experiments upon his 
 own person, that, within thirteen minutes after taking half an ounce 
 
 ' Cl. Bernard. Lectures on tlie Blood ; reported by W. F. Atlee, M. D. Pliila- 
 delpMa, 1854, p. 31. 
 
 ^ Physiological Cliemistry. Philadelpliia ed., vol. i. p. 97. 
 
PHOSPHATES OF MAGNESIA, SODA, AND POTASS, 45 
 
 of lactate of soda, the urine had an alkaline reaction. He also ob- 
 served that, if a solution of lactate of soda were injected into the 
 jugular vein of a dog, the urine became alkaline at the end of five, 
 or, at the latest, of twelve minutes. The conversion of these salts 
 into carbonates takes place, therefore, not in the intestine but in the 
 blood. The same observer' found that, in many persons living on 
 a mixed diet, the urine became alkaline in two or three hours after 
 swallowing ten grains of acetate of soda. These salts, therefore, 
 on being introduced into the animal body, are decomposed. Their 
 organic acid is destroyed and replaced by carbonic acid ; and they 
 are then discharged under the form of carbonates of soda and 
 potass. 
 
 7. Carbonate of Potass. — -This substance occurs in very nearly 
 tbe same situations as the last. In the blood, however, it is in 
 smaller quantity. It is mostly produced, as above stated, by the 
 decomposition of the malate, tartrate, and citrate, in the same 
 manner as the carbonate of soda. Its function is also the same as 
 that of the soda salt, and it is discharged in the same manner from 
 the body. 
 
 8, Phosphates of Magnesia, Soda, and Potass. — All these 
 substances exist universally in all the solids and fluids of the body, 
 but in very small quantity. The phosphates of soda and potass 
 are easily dissolved in the fluids, owing to their ready solubility in 
 water. The phosphate of magnesia is held in solution in the blood 
 by the alkaline chlorides and phosphates ; in the urine, by the acid 
 phosphate of soda. 
 
 A peculiar relation exists between the alkaline phosphates and 
 carbonates in different classes of animals. For while the fluids of 
 carnivorous animals contain a preponderance of phosphates, those 
 of the herbivora. contain a preponderance of the carbonates: a 
 peculiarity readily understood when we recollect that muscular 
 flesh and the animal tissues generally are comparatively abundant 
 in phosphates ; while vegetable substances abound in salts of the 
 organic acids, which give rise, as already described, by decomposi- 
 tion in the blood, to the alkaline carbonates. 
 
 The proximate principles included in the above list resemble 
 
 ' Physiological Chemistry, vol. ii. p. 130. 
 
46 PROXIMATE PRIXCIPLES OF THE FIRST CLASS. 
 
 each other not only in their inorganic origin, their crystallizability, 
 and their definite chemical composition, but also in the part which 
 they take in the constitution of the animal frame. They are 
 distinguished in this respect, first, by being derived entirely from 
 without. There are a few exceptions to this rule; as, for example, 
 in the case of the alkaline carbonates, which partly originate in 
 the body from the decomposition of malates, tartrates, &c. These, 
 however, are only exceptions ; and in general, the proximate prin- 
 ciples belonging to the first class are introduced with the food, 
 and taken up by the animal tissues in precisely the same form 
 under which they occur in external nature. The carbonate of lime 
 in the bones, the chloride of sodium in the blood and tissues, are 
 the same substances which are met with in the calcareous rocks, and 
 in solution in sea water. They do not suffer any chemical alteration 
 in becoming constituent parts of the animal frame. 
 
 They are equally exempt, as a general rule, from any alteration 
 while they remain in the body, and during their passage through 
 it. The exceptions to this rule are very few ; as, for example, where 
 a small part of the chloride of sodium suffers double decomposition 
 with phosphate of potass, giving rise to chloride of potassium and 
 phosphate of soda ; or where the phosphate of soda itself gives up 
 a part of its base to an organic acid (uric), and is converted in this 
 way into a bi-phosphate of soda. 
 
 Nearly the whole of these substances, finally, are taken up un- 
 changed from the tissues, and discharged unchanged with the excre- 
 tions. Thus we find the phosphate of lime and the chloride of so- 
 dium, which were taken in with the food, discharged again under the 
 same form in the urine. They do not, therefore, for the most -part, 
 participate directly in the chemical changes going on in the body ; 
 but only serve by their presence to enable those changes- to be 
 accomplished in the other ingredients of the animal frame, which 
 are necessary to the process of nutrition. 
 
PROXIMATE PRINCIPLES OF THE SECOND CLASS, 47 
 
 CHAPTER III. 
 
 PROXIMATE PRINCIPLES OF THE SECOND CLASS. 
 
 The proximate principles belonging to tlie second class are 
 divided into three principal groups, viz. : starch, sugar, and oil. 
 Thej are distinguished, in the first place, bj their organic origin. 
 Unlike the principles of the first class, they do not exist in 
 external nature, but are only found as ingredients of organized 
 bodies. They exist both in animals and in vegetables, though in 
 somewhat different proportions. All the substances belonging to 
 this class have a definite chemical composition ; and are further 
 distinguished by the fact that they are composed of oxygen, hydro- 
 gen, and carbon alone, without nitrogen, whence they are sometimes 
 called the " non-nitrogenous" substances. 
 
 1. Starch (C^JI^fi^^). The first of these substances seems to 
 form an exception to the general rule in a very important particular, 
 viz., that it is not crystallizable. Still, since it so closely resembles 
 the rest in all its general properties, and since it is easily converti- 
 ble into SQgar, which is itself crystallizable, it is naturally included 
 in the second class of proximate principles. Though not crystal- 
 lizable, furthermore, it still does assume a distinct form, by which 
 it differs from substances that are altogether amorphous. 
 
 Starch occurs in some part or other of almost all the flowering 
 plants. It is very abundant in corn, wheat, rye, oats, and rice, in 
 the parenchyma of the potato, in peas and beans, and in most vege- 
 table substances used as food. It constitutes almost entirely the 
 different preparations known as sago, tapioca, arrowroot, &c., which 
 are nothing more than varieties of starch, extracted from different 
 species of plants. 
 
 The following is a list showing the percentage of starch occurring 
 in different kinds of food : — ^ 
 
 ' Pereira on Food and Diet, p. 39. New York, 1843. 
 
48 
 
 PKOXIMATE PRINCIPLES OF THE SECOND CLASS. 
 
 Quantity of Starch 
 
 IN 100 PARTS IN 
 
 
 85.07 
 
 Wheat flour 
 
 56.50 
 
 80.92 
 
 Iceland moss 
 
 44.60 
 
 67.18 
 
 Kidney bean 
 
 35.94 
 
 61.07 
 
 Peas . 
 
 32.45 
 
 59.00 
 
 Potato 
 
 15.70 
 
 Rice . 
 Maize 
 
 Barley meal 
 Rye meal . 
 Oat meal . 
 
 When purified from foreign substances, starch is a white, liglit 
 powder, which gives rise to a peculiar crackling sensation when 
 
 rubbed between the fingers. 
 ■^"S- ^- It is not amorphous, as we 
 
 have already stated, but is 
 composed of solid granules, 
 which, while they have a 
 general resemblance to each 
 other, differ somewhat in va- 
 rious particulars. The starch 
 grains of the potato (Fig. 2), 
 vary considerably in size. 
 The smallest have a diameter 
 of lohoo, the largest ^^o of 
 an inch. They are irregu- 
 larly pear-shaped inform, and 
 are marked by concentric la- 
 minse, asifthematter of which 
 they are composed had been deposited in successive layers. At one 
 point on the surface of every starch grain, there is a minute pore or 
 
 depression, called the hilus, 
 
 Grains of Potato Starch. 
 
 Fig. 3. 
 
 Starch Grains of Bermcda Arrowroot. 
 
 around which the circular 
 markings are arranged in a 
 concentric form. 
 
 The starch granules of 
 arrowroot (Fig. 3) are gene- 
 rally smaller, and more uni- 
 form in size than those of 
 the potato. They vary from 
 2o'oo to 5-^0 of an inch in 
 diameter. They are elongated 
 and cylindrical in form, and 
 the concentric markings are 
 less distinct than in the pre- 
 ceding variety. The hilus 
 
STARCH. 
 
 49 
 
 Starch Grains op Wheat Flour. 
 
 bas here sometimes the form of a circular pore, and sometimes that 
 of a transverse fissure or slit. 
 
 The grains of wheat starch (Fig. 4) are still smaller than those 
 t)f arrowroot. They vary 
 from TOO 00 to ^lo of an inch 
 in diameter. They are 
 nearly circular in form, with 
 a round or transverse hilus, 
 but without any distinct 
 appearance of lamination. 
 Many of them are flattened 
 or compressed laterally, so 
 that they present a broad 
 surface in one position, and 
 a narrow edge when viewed 
 in the opposite direction. 
 
 The starch grains of In- 
 dian corn (Fig. 5), are of 
 nearly the same size with 
 those of wheat flour. They are somewhat more irregular and 
 angular in shape ; and are often marked with crossed or radiating 
 lines, as if from partial fracture. 
 
 Starch is also an ingre- 
 dient of the animal body. 
 It was first observed by 
 Purkinje, and afterward by 
 Koiliker, ' that certain bodies 
 are to be found in the interior 
 of the brain, about the lateral 
 ventricles, in the fornix, 
 septum lucidum, and other 
 parts which present a cer- 
 tain resemblance to starch 
 grains, and which have there- 
 fore been called "corpora 
 amylacea." Subsequently 
 Virchow^ corroborated the 
 above observations, and ascertained the corpora amylacea to be 
 
 ' Handbuch der Gewebelehre, Leipzig, 1852, p. 311. 
 * In American Journal Med. Sci., April, 1854, p. 466. 
 
 Starch Grains of Indian Corn. 
 
50 
 
 PROXIMATE PRINCIPLES OF THE SECOND CLASS. 
 
 Starch Grains from Wall of Lateral Ventricle ; 
 from a woman aged 35. 
 
 really substances of a starchy nature ; since they exhibit the usual 
 chemical reactions of vegetable starch. 
 
 The starch granules of the human brain (Fig. 6), are transparent 
 
 and colorless, like those from 
 plants. They refract the light 
 strongly, and vary in size 
 from 4^Vu to yyVo of an 
 inch. Their average is ygViy 
 of an inch. They are some- 
 times rounded or oval, and 
 sometimes angular in shape. 
 They resemble considerably 
 in appearance the starch 
 granules of Indian corn. The 
 largest of them present a 
 very faint concentric lamina- 
 tion, but the greater number 
 are destitute of any such 
 appearance. They have 
 nearly always a distinct hilus, which is sometimes circular and 
 sometimes slit-shaped. They are also often marked with delicate 
 radiating lines and shadows. On the addition of iodine, they become 
 colored, first purple, afterward of a deep blue. They are less firm 
 in consistency than vegetable starch grains, and can be more readily 
 disintegrated by pressing or rubbing them upon the glass. 
 
 Starch, derived from all these different sources, has, so far as known, 
 the same chemical composition, and may be recognized by the same 
 tests. It is insoluble in cold water, but in boiling water its granules 
 first swell, become gelatinous and opaline, then fuse together, and 
 finally liquefy altogether, provided a sufficient quantity of water be 
 present. After that, they cannot be made to resume their original 
 form, but on cooling and drying merely solidify into a homogeneous 
 mass or paste, more or less consistent, according to the quantity of 
 water which remains in union witb it. The starch is then said to 
 be amorphous or "hydrated." By this process it is not essentially 
 altered in its chemical properties, but only in its physical condition. 
 Whether in granules, or in solution, or in an amorphous and 
 hydrated state, it strikes a deep blue color on the addition of free 
 iodine. 
 
 Starch may be converted into sugar by three different methods. 
 First, by boiling with a dilute acid. If starch be boiled with dilute 
 
SUGAR. 51 
 
 nitric, sulphuric, or muriatic acid during thirty-six hours, it first 
 changes its opalescent appearance, and becomes colorless atid trans- 
 parent; losing at the same time its power of striking a blue color 
 with iodine. After a time, it begins to acquire a sweet taste, and 
 is finally altogether converted into a peculiar species of sugar. 
 
 Secondly, by contact with certain animal and vegetable sub- 
 stances. Thus, boiled starch, mixed with human saliva and kept 
 at the temperature of 100° F., is converted in a few minutes into 
 sugar. 
 
 Thirdly, by the processes of nutrition and digestion in animals 
 and vegetables. A large part of the starch stored up in seeds and 
 other vegetable tissues is, at some period or other of the growth of 
 the plant, converted into sugar by the molecular changes going on 
 in the vegetable fabric. It is in this way, so far as we know, that 
 all the sugar derived from vegetable sources has its origin. 
 
 Starch, as a proximate principle, is more especially important as 
 entering largely into the composition of many kinds of vegetable 
 food. With these it is introduced into the alimentary canal, and 
 there, during the process of digestion, is converted into sugar. 
 Consequently, it does not appear in the blood, nor in any of the 
 secreted fluids. 
 
 2. Sugar, — This group of proximate principles includes a con- 
 siderable number of substances, which differ in certain minor 
 details, while they resemble each other in the following particulars: 
 They are readily soluble in water, and crystallize more or less 
 perfectly on evaporation ; they have a distinct sweet taste ; and 
 finally, by the process of fermentation, they are converted into 
 alcohol and carbonic acid. 
 
 These substances are derived from both animal and vegetable 
 sources. Those varieties of sugar which are most familiar to us 
 are the following six, three of which are of vegetable and three of 
 animal origin. 
 
 fCane sugar, r Milk sugar, 
 
 ^ Animal ^ . 
 Grape sugar, < Liver sugar, 
 
 Sugar of starch. ° V Sugar of honey. 
 
 The cane and grape sugars are held in solution in the juices of 
 the plants from which they derive their name. Sugar of starch, or 
 glucose^ is produced by boiling starch for a long time with a dilute 
 acid. Liver sugar and the sugar of milk are produced in the 
 tissues of the liver and the mammary gland, and the sugar oi 
 
52 PROXIMATE PRINCIPLES OF THE SECOND CLASS. 
 
 honey is prepared in some way by the bee from materials of vege- 
 table origin. 
 
 These varieties cliflfer but little in their ultimate chemical compo- 
 sition. The following formulae have been established for three of 
 them. 
 
 Cane sugar ......= C24H220^ 
 
 Milk siigar = Cj^Hj^Oj^ 
 
 Glucose = C^jH28023 
 
 Cane sugar is sweeter than most of the other varieties, and more 
 soluble in water. Some sugars, such as liver sugar and sugar of 
 honey, crystallize only with great difficulty; but this is probably 
 owing to their being mingled with other substances, from which it 
 is difficult to separate them completely. If they could be obtained 
 in a state of purity, they would doubtless crystallize as perfectly as 
 cane sugar. The different sugars vary also in the readiness with 
 which they undergo fermentation. Some of them, as grape sugar 
 and liver sugar, enter into fermentation very promptly ; others, such 
 as milk and cane sugar, with considerable difficulty. 
 
 The above are not to be regarded as the only varieties of sugar 
 existing in nature. On the contrary, it is probable that nearly 
 every different species of animal and vegetable produces a distinct 
 kind of sugar, differing slightly from the rest in its degree of sweet- 
 ness, its solubility, its crystallization, its aptitude for fermentation, 
 and perhaps in its elementary composition. Nevertheless, there is 
 so close a resemblance between them that they are all properly 
 regarded as belonging to a single group. 
 
 The test most commonly employed for detecting the presence 
 of suffar is that known as Trommer's test. It depends upon the fact 
 that the saccharine substances have the power of reducing the 
 persalts of copper when heated with them in an alkaline solution. 
 The test is applied in the following manner : A very small quantity 
 of sulphate of copper in solution should be added to the suspected 
 liquid, and the mixture then rendered distinctly alkaline by the 
 addition of caustic potass. The whole solution then takes a deep 
 blue color. On boiling the mixture, if sugar be present, the 
 insoluble suboxide of copper is thrown down as an opaque red, 
 yellow, or orange colored deposit ; otherwise no change of color 
 takes place. 
 
 This test requires some precautions in its application. In the 
 first place, it is hot applicable to all varieties of sugar. Cane 
 sugar, for example, when pure, has no power of reducing the salts 
 
SUGAR. 53 
 
 of copper, even when present in large quantity. Maple sugar, 
 also, which resembles cane sugar in some other respects, reduces 
 the copper, in Trommer's test, but slowly and imperfectly. Beet- 
 root sugar, according to Bernard, presents the same peculiarity. If 
 these sugars, however, be boiled for two or three minutes with a 
 trace of sulphuric acid, they become converted into glucose, and 
 acquire the power of reducing the salts of copper. Milli sugar, 
 liver sugar, and sugar of honey, as well as grape sugar and glucose 
 all act promptly and perfectly with Trommer's test in their natural 
 condition. 
 
 Secondly, care must be taken to add to the suspected liquid only 
 a small quantity of sulphate of copper, just sufficient to give to the 
 whole a distinct blue tinge, after the addition of the alkali. If a 
 larger quantity of the copper salt be used, the sugar in solution 
 may not be sufficient to reduce the whole of it ; and that which 
 remains as a blue sulphate will mask the yellow color of the sub- 
 oxide thrown down as a deposit. By a little care, however, in 
 managing the test, this source of error may be readily avoided. 
 
 Thirdly, there are some albuminous substances which have the 
 power of interfering with Trommer's test, and prevent the reduc- 
 tion of the copper, even when sugar is present. Certain animal 
 matters, to be more particularly described hereafter, which are 
 liable to be held in solution in the gastric juice, have this effect. 
 This source of error may be avoided, and the substances in ques- 
 tion eliminated when present, by treating the suspected fluid with 
 animal charcoal, or by evaporating and extracting it with alcohol 
 before the application of the test. 
 
 A less convenient but somewhat more certain test for sugar is 
 that o^ fermentation. The' saccharine fluid is mixed with a little 
 yeast, and kept at a temperature of 70° to 100° F. until the fer- 
 menting process is completed. By this process, as already men-J 
 tioned, the sugar is converted into alcohol and carbonic acid. The 
 gas, which is given off in minute bubbles during fermentation, 
 should be collected and examined. The remaining fluid is purified 
 by distillation and also subjected to examination. If the gas be 
 found to be carbonic acid, and the remaining fluid contain alcohol, 
 there can be no doubt that sugar was present at the commencement 
 of the operation. 
 
 The following list shows the percentage of sugar in various 
 articles of food.' 
 
 ' Pereira, op. cit., p. 55. 
 
54 
 
 PROXIMATE PRINCIPLES OF THE SECOND CLASS. 
 
 Quantity of Sugar in 100 parts in 
 
 Figs . 
 
 62.50 
 
 Wheat flour 
 
 4.20 to 8.48 
 
 Cherries 
 
 18.12 
 
 Rye meal . 
 
 3.28 
 
 Peaches 
 
 16.48 
 
 Indian meal 
 
 1.45 
 
 Tamarinds 
 
 12.50 
 
 Peas . 
 
 2.00 
 
 Pears 
 
 11.52 
 
 Cow's milk 
 
 4.77 
 
 Beets 
 
 9.00 
 
 Ass's milk 
 
 6.08 
 
 Sweet almonds 
 
 6.00 
 
 Human milk 
 
 6.50 
 
 Barley meal . 
 
 5.21 
 
 
 
 Beside the sugar, therefore, which is taken into the alimentary 
 canal in a pure form, a large quantity is also introduced as an in- 
 gredient of the sweet-flavored fruits and vegetables. All the 
 starchy substances of the food are also converted into sugar in the 
 process of digestion. Two of the varieties of sugar, at least, 
 originate in the interior of the body, viz., sugar of milk and liver 
 sugar. The former exists in a solid form in the substance of the 
 mammary gland, from which it passes in solution into the milk. 
 The liver sugar is found in the substance of the liver, and almost 
 always also in the blood of the hepatic veins. The sugar which is 
 introduced with the food, as well as that which is formed in the 
 liver, disappears by decomposition in the animal fluids, and does 
 not appear in any of the excretions. 
 
 8. Fats. — These substances, like the sugars, are derived from 
 both animal and vegetable sources. There are three principal 
 varieties of them, which may be considered as representing the 
 class, viz : — 
 
 Oleine ' . . = Cg^ H^^ 0,5 
 
 Margarine ......= C^g H^j 0,2 
 
 Stearine ......= Ci^gH^iO^y 
 
 The principal difference between the oleaginous and saccharine 
 substances, so far as regards their ultimate chemical composition, 
 is that in the sugars the oxygen and hydrogen always exist together 
 in the proportion to form water; while in the fats the proportions of 
 carbon and hydrogen are nearly the same, but that of oxygen is 
 considerably less. The fats are all fluid at a high temperature, but 
 assume the solid form on cooling. Stearine, which is the most 
 solid of the three, liquefies only at 148° F.; margarine at 118° F.; 
 while oleine remains fluid considerably below 100° F., and even 
 very near the freezing point of water. The fats are all insoluble 
 in water, but readily soluble in ether. When treated with a solu- 
 tion of a caustic alkali, they are decomposed, and as the result of 
 
FATS. 
 
 55 
 
 the decomposition tliere are formed two new bodies ; first, glycerine, 
 which is a neutral fluid substance, and secondly, a fatty acid, viz : 
 oleic, margaric, or stearic acid, corresponding to the kind of fat 
 which has been used in the experiment. The glycerine remains in 
 a free state, while the fatty acid unites with the alkali employed, 
 forming an oleate, margarate, or stearate. This combination is 
 termed a soap^ and the process by which it is formed is called 
 saponification. This process, however, is not a simple decomposition 
 of the fatty body, since it can only take place in the presence of 
 water; several equivalents of which unite with the elements of the 
 fatty body, and enter into the composition of the glycerine, &c., so 
 that the fatty acid and the glycerine together weigh more than the 
 original fatty substance which was decomposed. It is not proper, 
 therefore, to regard an oleaginous body as formed by the union of a 
 fatty acid with glycerine. It is formed, on the contrary, in all pro- 
 bability, by the direct combination of its ultimate chemical elements. 
 The different kinds of oil, fat, lard, suet, &c., contain the three 
 oleaginous matters mentioned above, mingled together in different 
 proportions. The more solid fats contain a larger quantity of 
 stearine and margarine; the less consistent varieties, a larger propor- 
 tion of oleine. Neither of the oleaginous matters, stearine, mar- 
 garine, or oleine, ever occur separately ; but in every fatty substance 
 they are mingled together, so that the more fluid of them hold in 
 solution the more solid. 
 Generally speaking, in the 
 living body, these mixtures 
 are fluid or nearly so ; for 
 though both stearine and 
 margarine are solid, when 
 pure, at the ordinary tem- 
 perature of the body, they 
 are held in solution, during 
 life, by the oleine with which 
 they are associated. After 
 death, however, as the body 
 cools, tlie stearine and mar- 
 garine sometimes separate 
 from the mixture in a crys- 
 talline form, since the oleine 
 can no longer hold in solution so large a quantity of them as it had 
 dissolved at a higher temperature. 
 
 Steakine crystallized from a Warm Solution in Oleine. 
 
56 PEOXIMATE PEINCIPLES OF THE SECOND CLASS. 
 
 These substances crystallize in very slender needles, which are 
 sometimes straight, but more often somewhat curved or wavy in 
 their outline. (Fig. 7.) 
 
 They are always deposited in a more or less radiated form ; and 
 have sometimes a very elegant, branched, or arborescent arrange- 
 ment. 
 
 When in a fluid state, the fatty substances present themselves 
 
 under the form of drops or 
 globules, which vary indefi- 
 nitely in size, but which 
 may be readily recognized 
 by their optical properties. 
 They are circular in shape, 
 and have a faint amber color, 
 distinct in the larger globules, 
 less so in the smaller. They 
 have a sharp, well defined 
 outline (Fig. 8); and as they 
 refract the light strongly, 
 and act therefore as double 
 convex lenses, they present 
 a brilliant centre, surrounded 
 by a dark border. These 
 marks will generally be 
 sufficient to distinguish them under the microscope. 
 
 The following list shows the percentage of oily matter present in 
 various kinds of animal and vegetable food.* 
 
 Oleaginous Principles of Human Fat. Stearine and 
 Margarine crystallized; Oleine Fluid. 
 
 Quantity of Fat in 100 parts in 
 
 Filberts . 
 Walnuts 
 Cocoa-nuts 
 Olives . 
 Linseed . 
 Indian corn 
 Yolk of eggs 
 
 60.00 
 50.00 
 47.00 
 32.00 
 22.00 
 9.00 
 28.00 
 
 Ordinary meat 
 Liver of the ox 
 Cow's milk . 
 Human milk . 
 Asses' milk . 
 Goat's milk . 
 
 14.30 
 3.89 
 3.13 
 3.55 
 0.11 
 3.32 
 
 The oleaginous matters present a striking peculiarity as to the 
 form under which they exist in the animal body ; a peculiarity 
 which distinguishes them from all the other proximate principles. 
 The rest of the proximate principles are all intimately associated 
 together by molecular union, so as to form either clear solutions or 
 
 Pereira, op. cit., p. 81. 
 
FATS. 67 
 
 homogeneous solids. Thus, the sugars of the blood are in solution 
 in water, in company with the albumen, the phosphate of lime, 
 chloride of sodium, and the like ; all of them equally distributed 
 throughout the entire mass of the fluid. In the bones and car- 
 tilages, the animal matters and the calcareous salts are in similarly 
 intimate union with each other ; and in every other part of the 
 body the animal and inorganic ingredients are united in the same 
 Avay. But it is different with the fats. For, while the three prin- 
 cipal varieties of oleaginous matter are always united with each 
 other, they are not united with any of the other kinds of proximate 
 principles; that is, with water, saline substances, sugars, or albu- 
 minous matters. Almost the only exception to this is in the nerv- 
 ous tissue; in which, according to Robin and Verdeil, the oily 
 matters seem to be united with an albuminoid substance. Another 
 exception is, perhaps, in the bile ; since some of the biliary salts 
 have the power of dissolving a certain quantity of fat. Every- 
 where else, instead of forming a homogeneous solid or fluid with 
 the other proximate principles, the oleaginous matters are found 
 in distinct masses or globules, which are suspended in serous fluids, 
 interposed in the interstices between the anatomical elements, in- 
 cluded in the interior of cells, or deposited in the substance of 
 fibres or membranes. Even in the vegetable tissues, the oil is 
 always deposited in this manner in distinct drops or granules. 
 
 Owing to this fact, the oils can be easily extracted from the 
 organized tissues by the employment of simply mechanical pro- 
 cesses. The tissues, animal or vegetable, are merely cut into small 
 pieces and subjected to pressure, by which the oil is forced out 
 from the parts in which it was entangled, and separated, without any 
 further manipulation, in a state of purity. A moderately elevated 
 temperature facilitates the operation by increasing the fluidity of 
 the oleaginous matter ; but no other chemical agency is required 
 for its separation. Under the microscope, also, the oil drops and 
 granules can be readily perceived and distinguished from the 
 remaining parts of the tissue, and can, moreover, be easily re- 
 cognized by the dissolving action of ether, which acts upon 
 them, as a general rule, without attacking the other proximate 
 principles. 
 
 Oils are found, in the animal body, most abundantly in the 
 adipose tissue. Here they are contained in the interior of the 
 adipose vesicles, the cavities of which they entirely fill, in a state 
 
58 
 
 PEOXIMATE PRINCIPLES OF THE SECOND CLASS. 
 
 Human Adipose Tissue. 
 
 of health. These vesicles are transparent, and have a somewhat 
 angular form, owing to their mutual compression. (Fig. 9.) They 
 
 vary in diameter, in the hu- 
 man subject, from ^^^ to ^^j^ 
 of an inch, and are composed 
 of a thin, structureless ani- 
 mal membrane, forming a 
 closed sac, in the interior of 
 which the oily matter is con- 
 tained. There is here, ac- 
 cordingly, no union whatever 
 of the oil with the other 
 proximate principles, but 
 only a mechanical inclusion 
 of them by the walls of the 
 vesicles. Sometimes, when 
 emaciation is going on, the 
 oil partially disappears from 
 the cavity of the adipose vesicle, and its place is taken by a watery 
 serum ; but the serous and oily fluids always remain distinct, and 
 occupy different parts of the cavity of the vesicle. 
 
 In the chyle, the oleaginous matter is in a state of emulsion or 
 suspension in the form of minute particles in a serous fluid. Its 
 
 subdivision is here more com- 
 Fig. 10. plete, and its molecules more 
 
 minute than anywhere else in 
 the body. It presents the ap- 
 pearance of a fine granular 
 dust, which has been known 
 by the name of the " molecu- 
 lar base of the chyle." A 
 few of these granules are to 
 be seen which measure xo^oo 
 of an inch in diameter ; but 
 they are generally much less 
 than this, and the greater part 
 are so small that they cannot 
 be accurately measured. (Fig. 
 10.) For the same reason 
 they do not present the bril- 
 liant centre and dark border of the larger oil-globules ; but appear 
 
 Chyle, from commencemeut of Thoracic Duct, from 
 the Dog. 
 
FATS. 
 
 59 
 
 o° o%^. 
 
 by transmitted light only as minute dark granules. The white 
 color and opacity of the chyle, as of all other fatty emulsions, 
 depend upon this molecular condition of the oily ingredients. The 
 albumen, salts, &c., which are in intimate union with each other, 
 and in solution in the water, would alone make a colorless and 
 transparent fluid; but the oily matters, suspended in distinct par 
 tides, which have a different refractive power from the serous fluid, 
 interfere with its transparency 
 and give it the white color and 
 opaque appearance which are 
 characteristic of emulsions. 
 The oleasfinous nature of these 
 particles is readily shown by 
 their solubility in ether. 
 
 In the milk, the oily matter 
 occurs in larger masses than 
 in the chyle. In cow's milk 
 (Fig. 11), these oil-drops, or 
 " milk-globules," are not quite 
 fluid, but have a pasty con- 
 sistency, owing to the large 
 quantity of margarine which 
 they contain, in proportion to 
 
 the oleine. When forcibly amalgamated with each other and 
 collected into a mass by prolonged beating or churning, they con- 
 stitute butter. In cow's milk, 
 the globules vary somewhat 
 in size, but their average 
 diameter is 40V0 of ^^ inch. 
 They are simply suspended 
 in the serous fluid of the 
 milk, and are not covered 
 with any albuminous mem- 
 brane. 
 
 In the cells of the laryn- 
 geal, tracheal, and costal car- 
 tilages (Fig. 12), there is 
 always more or less fat de- 
 posited in the form of round- 
 ed globules, somewhat simi- 
 
 , , PI •11 Cells OF Costal Cartilages, containing Oil-Globules. 
 
 lar to those 01 the milk. Human. 
 
 Globules of Cow's Milk. 
 
 Fia;. 12. 
 
60 PROXIMATE PRINCIPLES OF THE SECOND CLASS. 
 
 Hepatic Cells. Human. 
 
 In the glandular cells of the liver, oil occurs constantly, in a 
 state of health. It is here deposited in the substance of the cell 
 
 (Fig. 13), generally in smaller 
 globules than the preceding. 
 In some cases of disease, it 
 accumulates in excessive 
 quantity, and produces the 
 state known as fatty degene- 
 ration of the liver. This is 
 consequently only an ex- 
 aggerated condition of that 
 which normally exists in 
 health. 
 
 In the carnivorous ani- 
 mals, oil exists in considera- 
 ble quantity in the convo- 
 luted portion of the urini- 
 ferous tubules. (E'ig. 14.) It 
 is here in the form of granules and rounded drops, which some- 
 times appear to fill nearly the whole calibre of the tubules. 
 
 It is found also in the secreting cells of the sebaceous and other 
 
 glandules, deposited in the 
 same manner as in those of 
 the liver, but in smaller 
 quantity. It exists, beside, 
 in large proportion, in a 
 granular form, in the secre- 
 tion of the sebaceous gland- 
 ules. 
 
 It occurs abundantly in 
 the marrow of the bones, 
 both under the form of free 
 oil-globules and inclosed in 
 the vesicles of adipose tissue. 
 It is found in considerable 
 quantity in the substance of 
 the yellow wall of the corpus 
 luteum, and is the immediate 
 cause of the peculiar color of this body. 
 
 It occurs also in the form of granules and oil-drops in the 
 muscular fibres of the uterus (Fig. 15), in which it begins to be 
 
 Uriniferods Tubules of Dog, from Cortical Portion of 
 Kidney. 
 
FATS. 
 
 61 
 
 MrscnLAR Fibres of Human TJterits three weeks after 
 parturition. 
 
 deposited sood after delivery, and where it continues to be present 
 during the whole period of the resorption or involution of this organ. 
 
 lu all these instances, the oleaginous matters remain distinct in 
 form and situation from the 
 
 other ingredients of the ani- ^ig- 15. 
 
 mal frame, and are only me- 
 chanically entangled among 
 its fibres and cells, or im- 
 bedded separately in their 
 interior. 
 
 A large part of the fat 
 which is found in the body 
 may be accounted for by that 
 which is taken in with the 
 food, since oily matter occurs 
 in both animal and vegetable 
 substances. Fat is, however, 
 formed in the body, independ- 
 ently of what is introduced 
 with the food. This im- 
 portant fact has been definitely ascertained by the experiments of 
 MM. Dumas and Milne-Edwards on bees,* M. Persoz on geese,^ and 
 finally by those of M. Boussingault on geese, ducks, and pigs.^ The 
 observers first ascertained the quantity of fat existing in the whole 
 body at the commencement of the experiment. The animals were 
 then subjected to a definite nutritious regimen, in which the 
 quantity of fatty matter was duly ascertained by analysis. The 
 experiments lasted for a period varying, in different instances, from 
 thirty-one days to eight months; after which the animals were 
 killed and all their tissues examined. The result of tbese investi- 
 gations showed that considerably more fat had been accumulated 
 by the animal during the course of the experiment than could be 
 accounted for by that which existed in the food; and placed it 
 beyond a doubt that oleaginous substances may be, and actually 
 are, formed in the interior of tbe animal body by the decomposition 
 or metamorphosis of other proximate principles. 
 
 It is not known from what proximate principles the fat is pro- 
 duced, when it originates in this way in the interior of the body. 
 Particular kinds of food certainly favor its production and accu- 
 
 ' Annales de China, et de Phys., 3d series, vol. xiv. p. 400. 
 ^ Chimie Agdcole, Paris, 1854. 
 
 2 Ibid., p. 408. 
 
62 proxi:mate peixciples of the secoxd class, 
 
 mulation to a considerable degree. It is well known, for instance, 
 that in sugar-growing countries, as in Louisiana and the West 
 Indies, during the few weeks occupied in gathering the cane and 
 extracting the sugar, all the negroes employed on the plantations, 
 and even the horses and cattle, that are allowed to feed freely on 
 the saccharine juices, grow remarkably fat; and that they again lose 
 their superabundant flesh when the season is past. Even in these 
 instances, however, it is not certain whether the saccharine substances 
 are directly converted into fat, or whether they are first assimilated 
 and only afterward supply the materials for its production. The 
 abundant accumulation of fat in certain regions of the body, and its 
 absence in others; and more particularly its constant occurrence in 
 certain situations to which it could not be transported by the blood, 
 as for example the interior of the cells of the costal cartilages, the 
 substance of the muscular fibres of the uterus after parturition, &c,, 
 make it probable that under ordinary conditions the oily matter is 
 formed by decomposition of the tissues upon the very spot where it 
 subsequently makes its appearance. 
 
 In the female during lactation a large part of the oily matter in- 
 troduced with the food, or formed in the body, is discharged with 
 the milk, and goes to the support of the infant. But in the female 
 in the intervals of lactation, and in the male at all times, the oily 
 matters almost entirely disappear by decomposition in the interior 
 of the body ; since the small quantity which is discharged with the 
 sebaceous matter by the skin bears only an insignificant proportion 
 to that which is introduced daily with the food. 
 
 The most important characteristic, in a physiological point of 
 view, of the proximate principles of the second class, relates to their 
 origin and their final destination. Not only are they all of a purely 
 organic origin, making their appearance first in the interior of vege- 
 tables ; but the sugars and the oils are formed also, to a certain ex- 
 tent, in the bodies of animals; continuing to make their appearance 
 when no similar substances, or only an insufficient quantity of them, 
 have been taken with the food. Furthermore, when introduced 
 with the food, or formed in the body and deposited in the tissues, 
 these substances do not reappear in the secretions. They, therefore, 
 for the most part disappear by decomposition in the interior of the 
 body. They pass through a series of changes by which their es- 
 sential characters are destroyed ; and they are finally replaced in 
 the circulation by other substances, which are discharged with the 
 excreted fluids. 
 
PROXIMATE PRINCIPLES OF THE THIRD CLASS. 63 
 
 CHAPTER IV. 
 
 PROXIMATE PRINCIPLES OF THE THIRD CLASS. 
 
 The substances belonging to this class are very important, and 
 form by far the greater part of the entire mass of the body. They 
 are derived both from animal and vegetable sources. They have 
 been known by the name of the "protein compounds" and the 
 " albuminoid substances." The name organic substances was given 
 to them by Robin and Verdeil, by whom their distinguishing pro- 
 perties were first accurately described. They have not only an 
 organic origin, in common with the proximate principles of the 
 second class, but their chemical constitution, their physical struc- 
 ture and characters, and the changes which they undergo, are all so 
 different from those met with in any other class, that the term "or- 
 ganic substances" proper, appears particularly appropriate to them. 
 
 Their first peculiarity is that they are not crystallizable. They 
 always, when pure, assume an amorphous condition, which is some- 
 times solid (organic substance of the bones), sometimes fluid (albu- 
 men of the blood), and sometimes semi-solid in consistency, midway 
 between the solid and fluid condition (organic substance of the mus- 
 cular fibre). 
 
 Their chemical constitution differs from that of bodies of the 
 second class, first in the fact that they all contain the four chemical 
 elements, oxygen, hydrogen, carbon, and nitrogen ; while the starches, 
 sugars, and oils are destitute of the last named ingredient. The or- 
 ganic matters have therefore been sometimes known by the name 
 of the " nitrogenous substances," while the sugars, starch, and oils 
 have been called "non-nitrogenous." Some of the organic matters, 
 viz., albumen, fibrin, and casein, contain sulphur also, as an ingre- 
 dient; and others, viz., the coloring matters, contain iron. The 
 remainder consist of oxygen, hydrogen, carbon, and nitrogen alone. 
 
 The most important peculiarity, however, of the organic sub- 
 stances, relating to their chemical composition, is that it is not defi- 
 nite. That is to say, they do not always contain precisely the same 
 
64 PEOXIMATE PEIISrCIPLES OF THE THIED CLASS. 
 
 proportions of oxygen, hydrogen, carbon, and nitrogen ; but the re- 
 lative quantities of these elements vary within certain limits, in 
 different individuals and at different times, without modifying, in 
 any essential degree, the peculiar properties of the animal matters 
 which they constitute. This fact is altogether a special one, and 
 characteristic of organic substances. No substance having a definite 
 chemical composition, like phosphate of lime, starch, or olein, can 
 suffer the slightest change in its ultimate constitution without being, 
 by that fact alone, totally altered in its essential properties. If 
 phosphate of lime, for example, were to lose one or two equivalents 
 of oxygen, an entire destruction of the salt would necessarily result, 
 and it would cease to be phosphate of lime. For its properties as a 
 salt depend entirely upon its ultimate chemical constitution; and if 
 the latter be changed in any way, the former are necessarily lost. 
 
 But the properties which distinguish the organic substances, and 
 which make them important as ingredients of the body, do not 
 depend immediately upon their ultimate chemical constitution, and 
 are of a peculiar character ; being such as are only manifested in the 
 interior of the living organism. Albumen, therefore, though it may 
 contain a few equivalents more or less of oxygen or nitrogen, does 
 not on that account cease to be albumen, so long as it retains its 
 fluidity and its aptitude for undergoing the processes of absorption 
 and transformation, which characterize it as an ingredient of the 
 living body. 
 
 It is for this reason that considerable discrepancy has existed at 
 various times among chemists as to the real ultimate composition 
 of these substances, different experimenters often obtaining different 
 analytical results. This is not owing to any inaccuracy in the 
 analyses, but to the fact that the organic substance itself really has 
 a different ultimate constitution at different times. The most ap- 
 proved formulae are those which have been established by Liebig 
 for the following substances: — 
 
 Fibrin = C29gH228N4o092S2 
 
 Albumen = C2,6H,g9N270g8S2 
 
 Casein ......= C288H22sN3gOggS2 
 
 Owing to the above mentioned variations, however, the same 
 degree of importance does not attach to the quantitative ultimate 
 analysis of an organic matter, as to that of other substances. 
 
 This absence of a definite chemical constitution in the organic sub- 
 stances is undoubtedly connected with their incapacity for crystalli- 
 zation. It is also connected with another almost equally peculiar 
 
OEGANIC SUBSTANCES. 65 
 
 fact, viz., that although the organic substances unite with acids and 
 with alkalies, they do not play the part of an acid toward the base, 
 or of a base toward the acid ; for the acid or alkaline reaction of 
 the substance employed is nqt neutralized, but remains as strong- 
 after the combination as before. Furthermore, the union does not 
 take place, so far as can be ascertained, in any definite proportions. 
 The organic substances have, in fact, no combining equivalent; and 
 their molecular reactions and the changes which they undergo in 
 the body cannot therefore be expressed by the ordinary chemical 
 phrases which are adapted to inorganic substances. Their true 
 characters, as proximate principles, are accordingly to be sought for 
 in other properties than those which depend upon their exact ulti- 
 mate composition. 
 
 One of these characters is that they are hygroscopic. As met with 
 in different parts of the body, they present different degrees of con- 
 sistency; some being nearly solid, others more or less fluid. But on 
 being subjected to evaporation they all lose water, and are reduced 
 to a perfectly solid form. If after this desiccation they are exposed 
 to the contact of moisture, they again absorb water, swell, and 
 regain their original mass and consistency. This phenomenon is 
 quite different from that of capillary attraction, by which some in- 
 organic substances become moistened when exposed to the contact 
 of water; for in the latter case the water is simply entangled me- 
 chanically in the meshes and pores of the inorganic body, while that 
 which is absorbed by the organic matter is actually united with its 
 substance, and diffused equally throughout its entire mass. Every 
 organic matter is naturally united in this way with a certain quantity 
 of water, some more and some less. Thus the albumen of the blood 
 is in union with so much water that it has the fluid form, while the 
 organic substance of cartilage contains less and is of a firmer con- 
 sistency. The quantity of water contained in each organic sub- 
 stance may be diminished by artificial desiccation, or by a deficient 
 supply ; but neither of them can be made to take up more than a 
 certain amount. Thus if the albumen of the blood and the organic 
 substance of cartilage be both reduced by evaporation to a similar 
 degree of dryness and then placed in water, the albumen will absorb 
 so much as again to become fluid, but the cartilaginous substance 
 only so much as to regain its usual nearly solid consistency. Even 
 where the organic substance, therefore, as in the case of albumen, 
 becomes fluid under these circumstances, it is not exactly a solution 
 5 
 
66 PEOXIMATE PRINCIPLES OF THE THIRD CLASS. 
 
 of it in water, but only a reabsorption by it of that quantity of fluid 
 with which it is naturally associated. 
 
 Another peculiar phenomenon characteristic of organic substances 
 is their coagulation. Those which are naturally fluid suddenly as- 
 sume, under certain conditions, a solid or semi-solid consistency. 
 They are then said to be coagulated; and after coagulation they 
 cannot be made to reassume their original condition. Thus fibrin 
 coagulates on being withdrawn from the bloodvessels, albumen on 
 being subjected to the temperature of boiling water, casein on being 
 placed in contact with an acid. When an organic substance thus 
 coagulates, the change which takes place is a peculiar one, and has 
 no resemblance to the precipitation of a solid substance from a 
 watery solution. On the contrary, the organic substance merely 
 assumes a special condition; and in passing into the solid form it 
 retains all the water with which it was previously united. Albumen, 
 for example, after coagulation, retains the same quantity of water in 
 union with it, which it held before. After coagulation, accordingly, 
 this water may be driven off by evaporation, in the same manner as 
 previously; and on being again exposed to moisture, the organic 
 matter will again absorb the same quantity, though it will not re- 
 sume the fluid form. 
 
 By coagulation, an organic substance is permanently altered ; 
 and though it may be afterwards dissolved by certain chemical re- 
 agents, as, for example, the caustic alkalies, it is not thereby restored 
 to its original condition, but only suffers a still further alteration. 
 
 In many instances we are obliged to resort to coagulation in order 
 to separate an organic substance from the other proximate principles 
 with which it is associated. This is the case, for example, with the 
 fibrin of the blood, which is obtained in the form of flocculi, by 
 beating freshly drawn blood with a bundle of rods. But when 
 separated in this way, it is already in an unnatural condition, and 
 no longer represents exactly the original fluid fibrin, as it existed 
 in the circulating blood. Nevertheless, this is the only mode in 
 which it can be examined, as there are no means of bringing it back 
 to its previous condition. 
 
 Another important property of the organic substances is that 
 they readily excite, in other proximate principles and in each other, 
 those peculiar indirect chemical changes which are termed catalyses 
 or catalytic transformations. That is to say, they produce the changes 
 referred to, not directly, by combining with the substance which 
 suffers alteration, or with any of its ingredients; but simply by their 
 
 #* 
 
ORGANIC SUBSTANCES. 67 
 
 presence, which induces the chemical change in an indirect manner. 
 Thus, the organic substances of the intestinal fluids induce a cata- 
 lytic action by which starch is converted into sugar. The albumen 
 of the blood, by contact with the organic substance of the muscular 
 fibre, is transformed into a substance similar to it. The entire 
 process of nutrition, so far as the organic matters are concerned, 
 consists of such catalytic transformations. Many crystallizable 
 substances, which when pure remain unaltered in the air, become 
 changed if mingled with organic substances, even in small quantity. 
 Thus the casein of milk, after being exposed for a short time to a 
 warm atmosphere, becomes a catalytic body, and converts the sugar 
 of the milk into lactic acid. In this change there is no loss nor 
 addition of any chemical element, since lactic acid has precisely the 
 same ultimate composition with sugar of milk. It is simply a 
 transformation induced by the presence of the casein. Oily matters, 
 which are entirely unalterable when pure, readily become rancid at 
 warm temperatures, if mingled with an organic impurity. 
 
 Fourthly, The organic substances, when beginning to undergo 
 decay, induce in certain other substances the phenomenon of fer- 
 mentation. Thus, the mucus of the urinary bladder, after a short 
 exposure to the atmosphere, causes the urea of the urine to be con- 
 verted into carbonate of ammonia, with the development of gaseous 
 bubbles. The organic matters of grape juice, under similar circum- 
 stances, give rise to fermentation of the sugar, by which it is con- 
 verted into alcohol and carbonic acid. 
 
 Fifthly, The organic substances are the only ones capable of 
 undergoing the process of 'putrefaction. This process is a compli- 
 cated one, and is characterized by a gradual liquefaction of the ani- 
 mal substance, by many mutual decompositions of the saline matters 
 which are associated with it, and by the development of peculiarly 
 fetid and unwholesome gases, among which are carbonic acid, 
 nitrogen, sulphuretted, phosphoretted, and carburetted hydrogen, 
 and ammoniacal vapors. Putrefaction takes place constantly after 
 death, if the organic tissue be exposed to a moist atmosphere at a 
 moderately warm temperature. It is much hastened by the presence 
 of other organic substances, in which decomposition has already 
 commenced. 
 
 The organic substances are readily distinguished, by the above 
 general characters, from all other kinds of proximate principles. 
 They are quite numerous; nearly every animal fluid and tissue con- 
 taining at least one which is peculiar to itself. They have not as 
 yet been all accurately described. The following list, however, 
 
68 PEOXIMATE PRINCIPLES OF THE THIRD CLASS. 
 
 comprises the most important of them, and those with which we 
 are at present most thoroughly acquainted. The first seven are fluid, 
 or nearly so, and either colorless or of a faint yellowish tinge. 
 
 1. Fibrin. — Fibrin is found in the blood ; where it exists, in the 
 human subject, in the proportion of two to three parts per thousand. 
 It is fluid, and mingled intimately with the other ingredients of the 
 blood. It occurs also, but in much smaller quantity, in the lymph. 
 It is distinguished by what is called its "spontaneous" coagulation; 
 that is, it coagulates on being withdrawn from the vessels, or on the 
 occurrence of any stoppage to the circulation. It is rather more 
 abundant in the blood of some of the lower animals than in that of 
 the human subject. In general, it is found in larger quantity in 
 the blood of the herbivora than in that of the carnivora. 
 
 2. Albumen. — Albumen occurs in the blood, the lymph, the- 
 fluid of the pericardium, and in that of the serous cavities gene- 
 rally. It is also present in the fluid which may be extracted by 
 pressure from the muscular tissue. In the blood it occurs in the 
 proportion of about seventy-five parts per thousand. The white of 
 egg, which usually goes by the same name, is not identical with the 
 albumen of the blood, though it resembles it in some respects; it is 
 properly a secretion from the mucous membrane of the fowl's ovi- 
 duct, and should be considered as a distinct organic substance. 
 Albumen coagulates on being raised to the temperature of 160° F.; 
 and the coagulum, like that of all the other proximate principles, is 
 soluble hi caustic potass. It coagulates also by contact with alco- 
 hol, the mineral acids, ferrocyanide of potassium in an acidulated 
 solution, tannin, and the metallic salts. The alcoholic coagulum, if 
 separated from the alcohol by washing, does not redissolve in water. 
 A very small quantity of albumen has been sometimes found in the 
 saliva. 
 
 3. Casein. — This substance exists in milk, in the proportion of 
 about forty parts per thousand. It coagulates by contact with all 
 the acids, mineral and organic ; but is not affected by a boiling 
 temperature. It is coagulated also by the juices of the stomach. 
 It is important as an article of food, being the principal organic in- 
 gredient in all the preparations of milk. In a coagulated form, it 
 constitutes the different varieties of cheese, which are more or less 
 highly flavored with various oily matters remaining entangled in 
 the coagulated casein. 
 
GLOBULINE. — MUCOSINE. 69 
 
 What is called vegetable casein or "legumine," is different from 
 the casein of milk, and constitutes the organic substance present in 
 various kinds of peas and beans. 
 
 4. Globuline. — This is the organic substance forming the prin- 
 cipal mass of the red globules of the blood. It is nearly fluid in 
 its natural condition, and readily dissolves in water. It does not 
 dissolve, however, in the serum of the blood; and the globules, 
 therefore, retain their natural form and consistency, unless the 
 serum be diluted with an excess of water, Globuline resembles 
 albumen in coagulating at the temperature of boiling water. It is 
 said to differ from it, however, in not being coagulated by contact 
 with alcohol. 
 
 5. Pepsine. — This substance occurs as an ingredient in the 
 gastric juice. It is not the same with the substance which Schwann 
 extracted by maceration from the mucous membrane of the stomach, 
 and which is regarded by Kobin, Bernard, &c., as only an artificial 
 product of the alteration of the gastric tissues. There seems no 
 good reason, furthermore, why we should not designate by this 
 name the organic substance which really does exist in the gastric 
 juice. It occurs in this fluid in very small quantity, not over 
 fifteen parts per thousand. It is coagulable by heat, and also by 
 contact with alcohol. But if the alcoholic coagulum be well 
 washed, it is again soluble in a watery acidulated fluid. 
 
 6. Panceeatine. — This is the organic substance of the pancreatic 
 juice, where it occurs in great abundance. It coagulates by heat, 
 and by contact with sulphate of magnesia in excess. In its natural 
 condition it is fluid, but has a considerable degree of viscidity. 
 
 7. MucosiNE is the organic substance which is found in the dif- 
 ferent varieties of mucus, and which imparts to them their viscidity 
 and other physical characters. Some of these mucous secretions 
 are so mixed with other fluids, that their consistency is more or less 
 diminished ; others which remain pure, like that secreted by the 
 mucous follicles of the cervix uteri, have nearly a semi-solid con- 
 sistency. But little is known with regard to their other specific 
 characters. 
 
 The next three organic substances are solid or semi-solid in con- 
 sistency. 
 
70 PKOXIMATE PEINCIPLES OF THE THIRD CLASS. 
 
 8. OSTEINE is the organic substance of the bones, in which it is 
 associated with a large proportion of phosphate of lime. It exists, 
 in those bones which have been examined, in the proportion of 
 about two hundred parts per thousand. It is this substance which 
 by long boiling of the bones is transformed into gelatine or glue. 
 In its natural condition, however, it is insoluble in water, even at 
 the boiling temperature, and becomes soluble only after it has been 
 permanently altered by ebullition. 
 
 9. Cartilagine. — This forms the organic ingredient of cartilage. 
 Like that of the bones, it is altered by long boiling, and is converted 
 into a peculiar kind of gelatine termed " chondrine." Chondrine 
 differs from the gelatine of bones principally in being precipitated 
 by acids and certain metallic salts which have no effect on the 
 latter. Cartilagine, in its natural condition, is very solid, and is 
 closely united with the calcareous salts. 
 
 10. MuscuLiNE. — This substance forms the principal mass of the 
 muscular fibre. It is semi-solid, and insoluble in water, but soluble 
 in dilute muriatic acid, from which it may be again precipitated by 
 neutralizing with an alkali. It closely resembles albumen in its 
 chemical composition, and like it, contains, according to Scherer, 
 two equivalents of sulphur. 
 
 The four remaining organic substances form a somewhat peculiar 
 group, Tliey are the coloring matters of the body. They exist 
 always in small quantity, compared with the other ingredients, but 
 communicate to the tissues and fluids a very distinct coloration. 
 They all contain iron as one of their ultimate elements. 
 
 11. H^matine is the coloring matter of the red globules of the 
 blood. It is nearly fluid like the globuline, and is united with it 
 in a kind of mutual solution. It is much less abundant than the 
 globuline, and exists in the proportion of about one part of hsema- 
 tine to seventeen parts of globuline. The following is the formula 
 for its composition which is adopted by Lehmann : — 
 
 Hsematine ^ C44H22N30gFe. 
 
 When the blood-globules from any cause become disintegrated, 
 the hsematine is readily imbibed after death by the walls of the 
 bloodvessels and the neighboring parts, staining them of a deep red 
 color. This coloration has sometimes been mistaken for an evidence 
 
MELANIJSTE. — UEOSACINE. 71 
 
 of arteritis ; but is really a simple effect of post-mortem imbibition, 
 as above stated. 
 
 12. Melanine. — This is the blackish-brown coloring matter 
 which is found in the choroid coat of the eye, the iris, the hair, and 
 more or less abundantly in the epidermis. So far as can be ascer- 
 tained, the coloring matter is the same in all these situations. It is 
 very abundant in the black and brown races, less so in the yellow 
 and white, but is present to a certain extent in all. Even where 
 the tinges produced are entirely different, as, for example, in brown 
 and blue eyes, the coloring matter appears to be the same in cha- 
 racter, and to vary only in its quantity and the mode of its arrange- 
 ment ; for the tinge of an animal tissue does not depend on its 
 local pigment only, but also on the muscular fibres, fibres of areolar 
 tissue, capillary bloodvessels, &c. All these ingredients of the* 
 tissue are partially transparent, and by their mutual interlacement 
 and superposition modify more or less the effect of the pigment 
 which is deposited below or among them. 
 
 Melanine is insoluble in water and the dilute acids, but dissolves 
 slowly in caustic potass. Its ultimate composition resembles that 
 of hsematine, but the proportion of iron is smaller. ^ 
 
 13. BiLiVERDiNE is the coloring matter of the bile. It is yellow 
 by transmitted light, greenish by reflected light. On exposure to 
 the air in its natural fluid condition, it absorbs oxygen and assumes 
 a bright grass green color. The same effect is produced by treating 
 it with nitric acid or other oxidizing substances. It occurs in very 
 small quantity in the bile, from which it may be extracted by pre- 
 cipitating it with milk of lime (Robin), from which it is afterward 
 separated by dissolving out the lime with muriatic acid. Obtained 
 in this form, however, it is insoluble in water, having been coagu- 
 lated by contact with the calcareous matter; and is not, therefore, 
 precisely in its original condition. 
 
 14. Ubosacine is the yellowish-red coloring matter of the urine. 
 It consists of the same ultimate elements as the other coloring mat- 
 ters, but occurs in the urine in such minute quantity, that the 
 relative proportion of its elements has never been determined. It 
 readily adheres to insoluble matters when they are precipitated from 
 the urine, and is consequently found almost always, to a greater or 
 less extent, as an ingredient in urinary calculi formed of the urates 
 
72 PEOXIMATE PEINCIPLES OF THE THIKD CLASS. 
 
 or of uric acid. When tlie urates are thrown down also in the form 
 of a powder, as a urinary deposit, they are usually colored more or 
 less deeply, according to the quantity of urosacine which is preci- 
 pitated with them. 
 
 The organic substances which exist in the body require for their 
 production an abundant supply of similar substances in the food. 
 All highly nutritious articles of diet, therefore, contain more or less 
 of these substances. Still, though nitrogenous matters must be 
 abundantly supplied, under some form, from without, yet the par- 
 ticular kinds of organic substances, characteristic of the tissues, are 
 formed in the body by a transformation of those which are intro- 
 duced with the food. The organic matters derived from vegetables, 
 though similar in their general characters to those existing in the 
 animal body, are yet specifically different. The gluten of wheat, 
 th/e legumine of peas and beans, are not the same with animal al- 
 bumen and fibrin. The only organic substances taken with animal 
 food, as a general rule, are the albumen of eggs, the casein of milk, 
 and the musculine of flesh ; and even these, in the food of the 
 human species, are so altered and coagulated by the process of 
 cooking, as to lose their specific characters before being introduced 
 into the alimentary canal. They are still further changed by the 
 process of digestion, and are absorbed under another form into the 
 blood. But from their, subsequent metamorphoses there are formed, 
 in the different parts of the body, osteine, cartilagine, haematine, 
 globuline, and all the other varieties of organic matter that cha- 
 racterize the different tissues. These varieties, therefore, originate 
 as such in the animal economy by the catalytic changes which the 
 ingredients of the blood undergo in nutrition. 
 
 Only a very small quantity of organic matter is discharged 
 with the excretions. The coloring matters of the bile and urine, 
 and the mucus of the urinary bladder, are almost the only ones 
 that find an exit from the body in this way. There is a minute 
 quantity of organic matter exhaled in a volatile form with the 
 breath, and a little also, in all probability, from the cutaneous sur- 
 face. But the entire quantity so discharged bears but a very small 
 proportion to that which is daily introduced with the food. The 
 organic substances, therefore, are decomposed in the interior of the 
 body. They are transformed by the process of destructive assimi- 
 lation, and their elements are finally eliminated and discharged 
 under other forms of combination. 
 
OF FOOD. 73 
 
 CHAPTER V. 
 
 OF FOOD. 
 
 Under the term " food" are included all those substances, solid 
 and liquid, which are necessary to sustain the process of nutrition. 
 The first act of this process is the absorption from without of all 
 those materials which enter into the composition of the living 
 frame, or of others which may be converted into them in the in- 
 terior of the body. 
 
 The proximate principles of the first class, or the "inorganic 
 substances," require to be supplied in sufficient quantity to keep up 
 the natural proportion in which they exist in the various solids and 
 fluids. As we have found it to be characteristic of these substances, 
 except in a few instances, that they suffer no alteration in the in- 
 terior of the body, but,- on the contrary, are absorbed, deposited in 
 its tissue, and pass out of it afterward unchanged, nearly every 
 one of them requires to be present under its own proper form, and 
 in sufficient quantity in the food. The alkaline carbonates, which 
 a,re formed, as we have seen, by a decomposition of the malates, 
 citrates and tartrates, constitute almost the only exception to this 
 rule. 
 
 Since water enters so largely into the composition of nearly every 
 part of the body, it is equally important as an ingredient of the 
 food. In the case of the human subject, it is probably the most 
 important substance to be supplied with constancy and regularity, 
 and the system suffers more rapidly when entirely deprived of 
 fluids, than when the supply of solid food only is withdrawn. A 
 man may pass eight or ten hours, for example, without solid food, 
 and suffer little or no inconvenience ; but if deprived of water for 
 the same length of time, he becomes rapidly exhausted, and feels 
 the deficiency in a very marked degree. Magendie found, in his 
 experiments on dogs subjected to inanition,^ that if the animals 
 
 ' Comptes Rendus, vol. xiii. p. 256. 
 
74 OF FOOD. 
 
 were supplied with water alone they lived six, eight, and even ten 
 days longer than if they were deprived at the same time of both 
 solid and liquid food. Chloride of sodium, also, is usually added 
 to the food in considerable quantity, and requires to be supplied 
 with tolerable regularity ; but the remaining inorganic materials, 
 such as calcareous salts, the alkaline phosphates, &c., occur natu- 
 rally in sufficient quantity in most of the articles which are used as 
 food. 
 
 The proximate principles of the second class, so far as they con- 
 stitute ingredients of the food, are naturally divided into two 
 groups : 1st, the sugar, and 2d, the oily matters. Since starch is 
 always converted into sugar in the process of digestion, it may be 
 included, as an alimentary substance, in the same group with the 
 sugars. There is a natural desire in the human species for both 
 saccharine and oleaginous food. In the purely carnivorous animals, 
 however, though no starch or sugar be taken, yet the body is main- 
 tained in a healthy condition. It has been supposed, therefore, that 
 saccharine matters could not be absolutely necessary as food ; the 
 more so since it has been found, by the experiments of CI. Bernard, 
 that, in carnivorous animals kept exclusively on a diet of flesh, 
 sugar is still formed in the liver, as well as in the mammary gland. 
 The above conclusion, however, which has been drawn from these 
 facts, does not apply practically to the human species. The car- 
 nivorous animals have no desire for vegetable food, while in the 
 human species there is a natural craving for it, which is almost 
 universal. It may be dispensed with for a few days, but not with 
 impunity for any great length of time. The experiment has often 
 enough been tried, in the treatment of diabetes, of confining the 
 patient to a strictly animal diet. It has been invariably found 
 that, if this regimen be continued for some weeks, the desire for 
 vegetable food on the part of the patient becomes so imperative 
 that the plan of treatment is U-navoidably abandoned. 
 
 A similar question has also arisen with regard to the oleaginous 
 matters. Are these substances indispensable as ingredients of the 
 food, or may they be replaced by other proximate principles, such 
 as starch or sugar? It has already been seen, from the experiments 
 of Boussingault and others, that a certain amount of fat is produced 
 in the body over and above that which is taken with the food ; and 
 it appears also that a regimen abounding in saccharine substances 
 is favorable to the production of fat. It is altogether probable, 
 therefore, that the materials for the production of fat may be 
 
OF FOOD. 70 
 
 derived, under these cii'cumstances, either directly or indirectly 
 from saccharine matters. But saccharine matters alone are not 
 entirely sufficient. M. Huber' thought he had demonstrated that 
 bees fed on pure sugar would produce enough wax to show that 
 the sugar could supply all that was necessary to the formation of 
 the fatty matter of the wax. Dumas and Milne-Edwards, however, 
 in repeating Huber's experiments,^ found that this was not the case. 
 Bees, fed on pure sugar, soon cease to work, and sometimes perish 
 in considerable numbers ; but if fed with honey, which contains 
 some v/axy and other matters beside the sugar, they thrive upon 
 it; and produce, in a given time, a much larger quantity of fat than 
 was contained in the whole supply of food. 
 
 The same thing was established by Boussingault with regard to 
 starchy matters. He found that in fattening pigs, though the 
 quantity of fat accumulated by the animal considerably exceeded 
 that contained in the food, yet fat must enter to some extent into 
 the composition of the food in order to maintain the animals in a 
 good condition ; for pigs, fed on boiled potatoes alone (an article 
 abounding in starch but nearly destitute of oily matter), fattened 
 slowly and with great difficulty ; while those fed on potatoes mixed 
 with a greasy flaid fattened readily, and accumulated, as mentioned 
 above, much more fat than was contained in the food. 
 
 The apparent discrepancy between these facts may be easily ex- 
 plained, when we recollect that, in order that the animal may become 
 fattened, it is necessary that he be supplied not only with the 
 materials of the fat itself, but also with everything else which is 
 necessary to maintain the body in a healthy condition. Oleaginous 
 matter is one of these necessary substances. The fats which are 
 taken in with the food are not destined to be simply transported 
 into the body and deposited there unchanged. On the contrary, 
 they are altered and used up in the processes of digestion and 
 nutrition ; while the fats which appear in the body as constituents 
 of the tissues are, in great part, of new formation, and are produced 
 from materials derived, perhaps, from a variety of different sources. 
 
 It is certain, then, that either one or the other of these two 
 groups of substances, saccharine or oleaginous, must enter into the 
 composition of the food; and furthermore, that, though the oily 
 matters may sometimes be produced in the body from the sugars, 
 
 ' Natural History of Bees, Edinboro', 1821, p. 330. 
 
 ^ Aimales de Chim. et de Phys., 3d series, vol. xiv. p. 400. 
 
76 OF FOOD. 
 
 it is also necessary for the perfect nutrition of the body that fat be 
 supplied, under its own form, with the food. For the human 
 species, also, it is natural to have them both associated in the 
 alimentary materials. They occur together in most vegetable sub- 
 stances, and there is a natural desire for them both, as elements 
 of the food. 
 
 They are not, however, when alone, or even associated with each 
 other, sufficient for the nutrition of the animal body. Magendie 
 found that dogs, fed exclusively on starch or sugar, perished after a 
 short time with symptoms of profound disturbance of the nutritive 
 functions. An exclusive diet of butter or lard had a similar effect. 
 The animal became exceedingly debilitated, though without much 
 emaciation ; and after death, all the internal organs and tissues 
 were found infiltrated with oil. Boussingault' performed a similar 
 experiment, with a like result, upon a duck, which was kept upon 
 an exclusive regimen of butter. " The duck received 1350 to 1500 
 grains of butter every day. At the end of three weeks it died of 
 inanition. The butter oozed from every part of its body. The 
 feathers looked as though they had been steeped in melted butter, 
 and the body exhaled an unwholesome odor like that of butyric 
 acid." 
 
 Lehmann was also led to the same result by some experiments 
 which he performed upon himself for the purpose of ascertaining 
 the effect produced on the urine by different kinds of food.^ 
 This observer confined himself first to a purely animal diet for 
 three weeks, and afterwards to a purely vegetable one for sixteen 
 days, without suffering any marked inconvenience. He then put 
 himself upon a regimen consisting entirely of non-nitrogenous sub- 
 stances, starch, sugar, gum, and oil, but was only able to continue 
 this diet for two, or at most for three days, owing to the marked 
 disturbance of the general health which rapidly supervened. The 
 unpleasant symptoms, however, immediately disappeared on his 
 return to an ordinary mixed diet. The same fact has been esta- 
 blished more recently by Dr. Wm. A. Hammond, Assistant Surgeon 
 U. S. Army,^ in a series of experiments which he performed upon 
 himself. He was enabled to live for ten days on a diet composed 
 exclusively of boiled starch and water. After the third day, how- 
 
 ■ Chimie Agricole, p. 166. 
 
 ^ Journal fiir praktische Chemie, vol. xxvii. p. 257. 
 
 * Experimental Researches, &c., being the Prize Essay of the American Medical 
 Association for 1857. 
 
OF FOOD. 77 
 
 ever, the general health began to deteriorate, and became verj much 
 disturbed before the termination of the experiment. The prominent 
 symptoms were debility, headache, pyrosis, and palpitation of the 
 heart. After the starchy diet was abandoned, it required some 
 days to restore the health to its usual condition. 
 
 The proximate principles of the third class, or the organic sub- 
 stances proper, enter so largely into the constitution of the animal 
 tissues and fluids, that their importance, as elements of the food, is 
 easily understood. No food can be long nutritious, unless a certain 
 proportion of these substances be present in it. Since they are so 
 abundant as ingredients of the body, their loss or absence from the 
 food is felt more speedily and promptly than that of any other sub- 
 stance except water. They have, therefore, sometimes received the 
 name of " nutritious substances," in cbntradistinction to those of 
 the second class, which contain no nitrogen, and which have been 
 found by the experiments of Magendie and others to be insufficient 
 for the support of life. The organic substances, however, when 
 taken alone, are no more capable of supporting life indefinitely than 
 the others. It was found in the experiments of the French " Gela- 
 tine Commission"^ that animals fed on pure fibrin and albumen, as 
 well as those fed on gelatine, become after a short time much en- 
 feebled, refuse the food which is offered to them, or take it with 
 reluctance, and finally die of inanition. This result has been ex- 
 plained by supposing that these substances, when taken alone, 
 excite after a time such disgust in the animal that they are either 
 no longer taken, or if taken are not digested. But this diso-ust 
 itself is simply an indication that the substances used are insufficient 
 and finally useless as articles of food, and that the system demands 
 instinctively other materials for its nourishment. 
 
 The instinctive desire of animals for certain substances is the 
 surest indication that they are in reality required for the nutritive 
 process ; and on the other hand, the indifference or repugnance 
 manifested for injurious or useless substances, is an equal evidence 
 of their unfitness as articles of food. This repugnance is well de- 
 scribed by Magendie, in the report of the commission above alluded 
 to, while detailing the result of his investigations on the nutritive 
 qualities of gelatine. " The result," he says, " of these first trials 
 was that pure gelatine was not to the taste of the dogs experimented 
 on. Some of them suffered the pangs of hunger with the gelatine 
 
 ' Comptes Eendus, 1841, vol. xiii. p. 267. 
 
78 OF FOOD. 
 
 within their reach, and would not touch it ; others tasted of it, but 
 wjould not eat: others still devoured a certain quantity of it once 
 or twice, and then obstinately refused to make any farther use of it." 
 
 In one instance, however, Magendie succeeded in inducing a dog 
 to take a considerable quantity of pure fibrin daily throughout the 
 whole course of the experiment; but notwithstanding this, the 
 animal became emaciated like the others, and died at last with the 
 same symptoms of inanition. 
 
 The alimentary substances of the second class, however, viz., the 
 sugars and the oils, have been sometimes thought less important 
 than the albuminous matters, because they do not enter so largely 
 or so permanently into the composition of the solid tissues. The 
 saccharine matters, when taken as food, cannot be traced farther 
 than the blood. They undergo already, in the circulating fluid, 
 some change by which their essential character is lost, and they 
 cannot be any longer recognized. The appearance of sugar in the 
 mammary gland and the milk is only exceptional, and does not 
 occur at all in the male subject. The fats are, it is true, very gene- 
 rally distributed throughout the body, but it is only in the brain 
 and nervous matter that they exist intimately united with thie re- 
 maining ingredients of the tissues. Elsewhere, as already mentioned, 
 it is deposited in distinct drops and granules, and so long as it re- 
 mains in this condition must of course remain inactive, so far as 
 reo-ards any chemical nutritive process. In this condition it seems 
 to be held in reserve, ready to be absorbed by the blood, whenever 
 it may be required for the purposes of nutrition. On being reab- 
 sorbed, however, as soon as it again enters the blood or unites 
 intimately with the substance of the tissues, it at once changes its 
 condition and loses its former chemical constitution and properties. 
 
 It is for these reasons that the albuminoid matters have been 
 sometimes considered as the only " nutritious" substances, because 
 they alone constitute under their own form a great part of the 
 ingredients of the tissues, while the sugars and the oils rapidly dis- 
 appear by decomposition. It has even been assumed that the pro- 
 cess by which the sugar and the oils disappear is one of direct 
 combustion or oxidation, and that they are destined solely to be 
 consumed in this way, not to enter at all into the composition of 
 tlie tissues, but only to maintain the heat of the body by an inces- 
 sant process of combustion in the blood. They have been therefore 
 termed the " combustible" or " heat-producing" elements, while the 
 
OF FOOD. 79 
 
 albuminoid substances were known as the nutritious or "plastic" 
 elements. 
 
 This distinction, however, has no real foundation. In the first 
 place, it is not at all certain that the sugars and the oils which dis- 
 appear in the body are destroyed by combustion. This is merely 
 an inference which has been made without any direct proof. All 
 we know positivel}^ in regard to the matter is that these substances 
 soon become so altered in the blood that they can no longer be 
 recognized by their ordinary chemical properties ; but we are still 
 ignorant of the exact nature of the transformations which they 
 undergo. Furthermore, the difference between the sugars and the 
 oils on the one hand, and the albuminoid substances on the other, 
 so far as regards their decomposition and disappearance in the body, 
 is only a difference of time. The albuminoid substances become 
 transformed more slowly, the sugars and the oils more rapidly. 
 Even if it should be ascertained hereafter that the sugars and the 
 oils really do not unite at all with the solid tissues, but are entirely 
 decomposed in the blood, this would not make them any less im- 
 portant as alimentary substances, since the blood is as essential a 
 part of .the body as the solid tissues, and its nutrition must be pro- 
 vided for equally with theirs. 
 
 It is evident, therefore, that no single proximate principle, nor 
 even any one class of them alone, can be sufficient for the nutrition 
 of the body; but that the food, to be nourishing, must contain 
 substances belonging to all the different groups of proximate prin- 
 ciples. The albuminoid substances are first in importance because 
 they constitute the largest part of the entire mass of the body ; and 
 exhaustion therefore follows more rapidly when they are withheld 
 than when the animal is deprived of other kinds of alimentary 
 matter. But starchy and oleaginous substances are also requisite ; 
 and the body feels the want of them sooner or later, though it may 
 be plentifully supplied with albumen and fibrin. Finally, the in- 
 organic saline matters, though in smaller quantity, are also neces- 
 sary to the continuous maintenance of life. In order that the 
 animal tissues and fluids remain in a healthy condition and take 
 their proper part in the functions of life, they must be supplied 
 with all the ingredients necessary to their constitution ; and a man 
 may be starved to death at last by depriving him of chloride of 
 sodium or phosphate of lime just as surely, though not so rapidly, 
 as if he were deprived of albumen or oil. 
 
 In the different kinds of food, accordingly, which have been 
 
80 OF FOOL*. 
 
 adopted by the universal and instinctive cTioice of man, the three 
 different classes of proximate principles are all more or less abund- 
 antly represented. In all of them there exists naturally a certain 
 proportion of saline substances ; and water and chloride of sodium 
 are gefnerally taken with them in addition. In milk, the first food 
 supplied to the infant, we have casein which is an albuminoid 
 substance, butter which represents the oily matters, and sugar of 
 milk belonging to the saccharine group, together with water and 
 saline matters, in the following proportions : — ^ 
 
 Composition of Cow's Milk. 
 
 Water 87.02 
 
 Casein ' . . . 4.48 
 
 Butter . . . . , 3.13 
 
 Sugar of milk 4.77 
 
 Soda 1 
 
 Chlorides of potassium and sodium ..... 
 
 Phosphates of soda and potass 
 
 Phosphate of lime • • .1-0.60 
 
 " magnesia . . 
 
 Alkaline carbonates . . . . 
 
 Iron, &c. . . . ■ . ■ • • • • • 
 
 100.00 
 
 In wheat flour, gluten is the albuminoid matter, sugar and starch 
 the non-nitrogenous principles. 
 
 
 Composition of Wheat Flouk. 
 
 
 Gluten . 
 
 . 10.2 Gum . 
 
 2.8 
 
 Starch . 
 
 . 72.8 Water . 
 4.2 
 
 . 10.0 
 
 Sugar . 
 
 
 100.0 
 
 The other cereal grains mostly contain oil in addition to the 
 above. 
 
 Composition op Dkied Oatmeal. 
 
 Starch 59.00 
 
 Bitter matter and sugar 8.25 
 
 Gray albuminous matter 4.30 
 
 Fatty oil 2.00 
 
 Gum • 2.50 
 
 Husk, mixture, and loss 23.95 
 
 100.00 
 Eggs contain albumen and salts in the white, with the addition 
 of oily matter in the yolk. 
 
 * The accompanying analyses of various kinds of food are taken from Pereira 
 on Food and Diet, New York, 1843. 
 
OF FOOD. 81 
 
 Composition of Eggs. 
 
 White of Egg. Yolk of Egg. 
 
 Water .... 80.00 53.78 
 
 Albumen and mucus . 15.28 12.75 
 
 Yellow oil ... 28.75 
 
 Salts .... 4.72 4.72 
 
 100.00 100.00 
 
 In ordinary flesh or butcher's meat, we have the albuminoid 
 
 matter of the muscular fibre and the fat of the adipose tissue. 
 
 Composition of Ordinary Butcher's Meat. 
 
 Meat devoid of fat . 85.7 | ^^^^^ .... 63.418 
 
 I Solid matter . . . 22.282 
 Fat, cellular tissue, &c 14.300 
 
 100.000 
 
 From what has been said above, it will easily be seen that the 
 nutritious character of any substance, or its value as an article of 
 food, does not depend simply upon its containing either one of the 
 alimentary substances mentioned above in large quantity ; but upon 
 its containing them mingled together in such proportion as is 
 requisite for the healthy nutrition of the body. What these pro- 
 portions are cannot be determined from simple chemical analysis, 
 nor from any other data than those derived from direct observation 
 and experiment. 
 
 The total quantity of food required by man has , been variously 
 estimated. It will necessarily vary, indeed, not only with the con- 
 stitution and habits of the individual, but also with the quality of 
 the food employed ; since some articles, such as corn and meat, con- 
 tain very much more alimentary material in the same bulk than 
 fresh fruits or vegetables. Any estimate, therefore, of the total 
 quantity should state also the kind of food used ; otherwise, it will 
 be altogether without value. From experiments performed while 
 living on an exclusive diet of bread, fresh meat, and butter, witb 
 coffee and water for drink, we have found that the entire quantity 
 of food required during twenty-four hours by a man in full health, 
 and taking free exercise in the open air, is as follows : — 
 
 Meat 16 ounces. 
 
 Bread . . . . , 19 " 
 
 Butter 3^ " 
 
 Fluids 52 " 
 
 That is to say, rather less than two and a half pounds of solid food, 
 and rather over three pints of liquid food. 
 6 
 
82 OF FOOD. 
 
 Another necessary consideration, in estimating the value of any 
 substance as an article of food, is its digestibility. A vegetable or 
 animal tissue may contain an abundance of albuminoid or starchy 
 matter, but may be at the same time of such an unyielding consist- 
 ency as to be insoluble in the digestive fluids, and therefore useless 
 as an article of food. Bones and cartilages, and the fibres of yel- 
 low elastic tissue, are indigestible, and therefore not nutritious. 
 The same remark may be made with regard to the substances con- 
 tained in woody fibre, and the hard coverings and kernels of various 
 fruits. Everything, accordingly, which softens or disintegrates a 
 hard alimentary substance renders it more digestible, and so far 
 increases its value as an article of food. 
 
 The preparation of food by cooking has a twofold object : first, 
 to soften or disintegrate it, and second, to give it an attractive 
 flavor. Many vegetable substances are so hard as to be entirely 
 indigestible in a raw state. Eipe peas and beans, the difierent kinds 
 of grain, and many roots and fruits, require to be softened by boil- 
 ing, or some other culinary process, before they are ready for use. 
 With them, the principal change produced by cooking is an altera- 
 tion in consistency. With most kinds of animal food, however, 
 the effect is somewhat different. In the case of muscular flesh, for 
 example, the muscular fibres themselves are almost always more or 
 less hardened by boiling or roasting ; but, at the same time, the 
 fibrous tissue by which they are held together is gelatinized and 
 softened, so that the muscular fibres are more easily separated from 
 each other, and more readily attacked by the digestive fluids. But 
 beside this, the organic substances contained in meat, which are all 
 of them very insipid in the raw state, acquire, by the action of heat 
 in cooking, a peculiar and agreeable flavor. This flavor excites 
 the appetite and stimulates the flow of the digestive fluids, and 
 renders, in this way, the entire process of digestion more easy and 
 expeditious. 
 
 The changes which the food undergoes in the interior of the body 
 may be included under three different heads : first, digestion^ or the 
 preparation of the food in the alimentary canal; second, assimila- 
 tion^ by which the elements of the food are converted into the ani- 
 mal tissues ; and third, excretion, by which it is again decomposed, 
 and finally discharged from the body. 
 
DIGESTION. 83 
 
 CHAPTER VI. 
 
 DIGESTION. 
 
 Digestion is that process by whicli the food is reduced to a form 
 iu which it can be absorbed from the intestinal canal, and taken up 
 by the bloodvessels. This process does not occur in vegetables. 
 For vegetables are dependent for their nutrition, mostly, if not 
 entirely, upon a supply of inorganic substances, as water, saline 
 matters, carbonic acid, and ammonia. These materials constitute 
 the food upon which plants subsist, and are converted in their inte- 
 rior into other substances, by the nutritive process. These mate- 
 rials, furthermore, are constantly supplied to the vegetable under 
 such a form as to be readily absorbed. Carbonic acid and ammonia 
 exist in a gaseous form in the atmosphere, and are also to be found 
 in solution, together with the requisiie saline matters, in the water 
 with which the soil is penetrated. All these substances, therefore, 
 are at once ready for absorption, and do not require any preliminary 
 modification. But with animals and man the case is different. 
 They cannot subsist upon these inorganic substances alone, but 
 require for their support materials which have already been organ- 
 ized, and which have previously constituted a part of animal or 
 vegetable bodies. Their food is almost nvariably solid or semi-solid 
 at the time when it is taken, and insoluble in water. Meat, bread, 
 fruits, vegetables, &g., are all taken into the stomach in a solid and 
 insoluble condition ; and even those substances which are naturally 
 fluid, such as milk, albumen, white of egg, are almost always, 
 in the human species, coagulated and solidified by the process of 
 cooking, before being taken into the stomach. 
 
 In animals, accordingly, the food requires to undergo a process 
 of digestion, or liquefaction, before it can be absorbed. In all cases, 
 the general characters of this process are the same. It consists 
 essentially in the food being received into a canal, running through 
 the body from mouth to anus, called the " alimentary canal," in 
 which it comes in contact with certain digestive fluids, which act 
 
84. , DIGESTION. 
 
 upon it in such a way as to liquefy and dissolve it. These fluids 
 are secreted by the mucous membrane of the alimentary canal, and 
 by certain glandular organs situated in its neighborhood. Since the 
 food always consists, as we have already seen, of a mixture of vari- 
 ous substances, having different physical and chemical properties, 
 the several digestive fluids are also different from each other ; each 
 one of them exerting a peculiar action, which is more or less con- 
 fined to particular species of food. As the food passes through the 
 intestine from above downward, those parts of it which become 
 liquefied are successively removed by absorption, and taken up by 
 the vessels ; while the remaining portions, consisting of the indiges- 
 tible matter, together with the refuse of the intestinal secretions, 
 gradually acquire a firmer consistency owing to the absorption of 
 the fluids, and are finally discharged from the intestine under the 
 form of feces. 
 
 In different species of animals, however, the difference in their 
 habits, in the constitution of their tissues, and in the character of 
 their food, is accompanied with a corresponding variation in the 
 anatomy of the digestive apparatus, and the character of the secreted 
 fluids. As a general rule, the digestive apparatus of herbivorous 
 animals is more complex than that of the carnivora ; since, in vege- 
 table substances, the nutritious matters are often present in a very 
 solid and unmanageable form, as, for example, in raw starch and 
 the cereal grains, and are nearly always entangled among vegetable 
 cells and fibres of an indigestible character. In those instances, 
 where the food consists mostly of herbage, as grass, leaves, &c., the 
 digestible matters bear only a small proportion to the entire quan- 
 tity; and a large mass of food must therefore be taken, in order 
 that the requisite amount of nutritious material may be extracted 
 from it. In such cases, accordingly, the alimentary canal is large 
 and long; and is divided into many compartments, in which 
 different processes of disintegration, transformation, and solution 
 are carried on. 
 
 In the common fowl, for instance (Fig. 16), the food, which con- 
 sists mostly of grains, and frequently of insects with hard, coria- 
 ceous integument, first passes down the oesophagus (a) into a 
 diverticulum or pouch (6) termed the crop. Here it remains for 
 a time, mingled with a watery secretion in which the grains are 
 macerated and softened. The food is then carried farther down 
 until it reaches a second dilatation (c), the proventriculus, or 
 secreting stomach. The mucous membrane here is thick and 
 
DIGESTION. 
 
 85 
 
 glandular, and is provided witli numerous se- Fig' 16. 
 
 creting follicles or crypts. From them an 
 acid fluid is poured out, by which the food is 
 subjected to further changes. It next passes 
 into the gizzard {d\ or triturating stomach, a 
 cavity inclosed by thick, muscular walls, and 
 lined with a remarkably tough and horny 
 epithelium. Here it is subjected to the crush- 
 ing and grinding action of the muscular 
 parietes, assisted by grains of sand and gravel, 
 which the animal instinctively swallows with 
 the food, by which it is so triturated and dis- 
 integrated, that it is reduced to a uniform pulp, 
 upon which the digestive fluids can effectually 
 operate. The mass then passes into the intes- 
 tine (e), where it meets with the intestinal 
 juices, which complete the process of solution; 
 and from the intestinal cavity it is finally ab- 
 sorbed in a liquid form, by the vessels of the 
 mucous membrane. 
 
 In the ox, again, the sheep, the camel, the 
 deer, and all ruminating animals, there are 
 four distinct stomachs through which the 
 food passes in succession; each lined with 
 mucous membrane of a different structure, 
 and adapted to perform a different part in 
 the digestive process (Fig. 17). When first 
 swallowed, the food is received into the ru- 
 men, or paunch (b), a large sac, itself par- 
 tially divided by incomplete partitions, and 
 lined by a mucous membrane thickly set 
 with long prominences or villi. Here it ac- 
 cumulates while the animal is feeding, and is 
 
 retained and macerated in its own fluids. When the anim.al has 
 finished browsing, and the process of rumination commences, the 
 food is regurgitated into the mouth by an inverted action of -tfee 
 muscular walls of the paunch and oesophagus, and slowly masticated. 
 It then descends again along the oesophagus ; but instead of enter- 
 ing the first stomach, as before, it is turned off by a muscular valve 
 into the second stomach, or reticulum (c), which is distinguished 
 by the intersecting folds of its mucous membrane, which give it 
 
 Alimentary Canal of Fowl. 
 — a. Oesophagus. 6. Crop, 
 c. Proventriculus, or secret- 
 ing stomach, d. Gizzard, or 
 triturating stomach, e. In- 
 testine. /. Two long cjecal 
 tubes which open into the in- 
 testine a short distance above 
 its termination. 
 
86 
 
 DIGESTION. 
 
 CoMPOu>T) Stomach of Ox. — a. CEsopliagus. 
 h. Rumen, or first stomach, e. Eeticulum, or 
 second, d. Omasus, or third, e. Obomasus, 
 or fourth. /. Duodenum. 
 
 a honey-combed or reticulated appearance. Here the food, already 
 
 tritura'ed in the mouth, and 
 ^^' mixed with the saliva, is further 
 
 macerated in the fluids swallowed 
 by the animal, which always ac- 
 cumulate in considerable quan- 
 tity in the reticulum. The next 
 cavity is the omasus^ or "psalte- 
 rium" (cf), in which the mucous 
 membrane is arranged in longi- 
 tudinal folds, alternately broad 
 and narrow, lying parallel with 
 each other, like the leaves of a 
 book, so that the extent of mucous 
 surface, brought in contact with 
 the food, is very much increased. 
 The exit from this cavity leads 
 directly into the obomasus^ or 
 " rennet" (e), which is the true 
 digestive stomach, in which the mucous membrane is softer, thicker, 
 and more glandular than elsewhere, and in which an acid and 
 highly solvent fluid is secreted. Then follows the intestinal canal 
 with its various divisions and variations. 
 
 In the carnivora, on the other hand, the alimentary canal is 
 shorter and narrower than in the preceding, and presents fewer 
 complexities. The food, upon which these animals subsist, is softer 
 than that of the herbivora, and less encumbered with indigestible 
 matter ; so that the process of its solution requires a less extensive 
 apparatus. 
 
 In the human species, the food is naturally of a mixed cha- 
 racter, containing both animal and vegetable substances. But the 
 digestive apparatus in man resembles almost exactly that of the 
 carnivora. For the vegetable matters which we take as food are, 
 in the first place, artificially separated, to a great extent, from indi- 
 gestible impurities ; and secondly, they are so softened by the 
 process of cooking as to become nearly or quite as easily digestible 
 as animal substances. 
 
 In the human species, however, the process of digestion, though 
 simpler than in the herbivora, is still complicated. The alimentary 
 canal is here, also, divided into different compartments or cavities, 
 which communicate with each other by narrow orifices. At its 
 
DIGESTION. 
 
 commencement (Fig. 18), we find the cavity of the mouth, which is 
 guarded at its posterior extremity by the muscular valve of the 
 isthmus of the fauces. 
 Through the pharynx and 
 oesophagus (a), it com- 
 municates with the second 
 compartment, or the sto- 
 mach (5), a flask-shaped 
 dilatation, which is guarded 
 at the cardiac and pyloric 
 orifices by circular bands 
 of muscular fibres. Then 
 comes the small intestine 
 (e), different parts of which, 
 owing to the varying struc- 
 ture of their mucous mem- 
 branes, have received the 
 different names of duode- 
 num, jejunum, and ileum. 
 In the duodenum, we have 
 the orifices of the biliary 
 and pancreatic ducts (/, g). 
 Finally, we have the large 
 intestine (/z, i, j\ k), separated 
 from the smaller by the 
 ileo-C8ecal valve, and ter- 
 minating, at its lower ex- 
 tremity, by the anus, at 
 which is situated a double 
 sphincter, for the purpose 
 of guarding its orifice. 
 Everywhere the alimentary 
 canal is composed of a 
 mucous membrane and a 
 muscular coat, with a layer 
 of submucous areolar tissue 
 between the two. The mus- 
 cular coat is everywhere 
 
 composed of a double layer of longitudinal and transverse fibres, 
 by the alternate contraction and relaxation of which the food is 
 carried through the canal from above downward. The mucous 
 
 Human Alimentary Canal. — a. (Esophagus. 6. Sto- 
 mach, c. Cardiac orifice, d. Pylorus, e. Small intestine. 
 /. Biliary duct. g. Pancreatic duct. h. Ascending colon. 
 i. Transverse colon. J. Descending colon, k. Rectum. 
 
88 DIGESTION". 
 
 membrane presents, also, a different structure, and has different 
 properties in different parts. In the mouth and oesophagus, it is 
 smooth, with a hard, whitish, and tessellated epithelium. This kind 
 of epithelium terminates abruptly at the cardiac orifice of the 
 stomach. The mucous membrane of the gastric cavity is soft and 
 glandular, covered with a transparent, columnar epithelium, and 
 thrown into minute folds or projections on its free surface, which 
 are sometimes reticulated with each other. In the small intestine, 
 we find large transverse folds of mucous membrane, the valvulce 
 conniventes, the minute villosities which cover its surface, and the 
 peculiar glandular structures which it contains. Finally, in the 
 large intestine, the mucous membrane is again different. It is here 
 smooth and shining, free from villosities, and provided with a 
 different glandular apparatus. 
 
 Furthermore, the digestive secretions, also, vary in these different 
 regions. In its passage from above downwards, the food meets 
 with no less than five different digestive fluids. First it meets with 
 the saliva in the cavity of the mouth ; second, with the gastric juice^ 
 in the stomach; third, with the hile ; fourth, with the pancreatic 
 fluid; and fifth, with the intestinal juice. It is the most important 
 characteristic of the process of digestion, as established by modern 
 researches, that different elements of the food are digested in different 
 parts of the alimentary canal by the agency of different digestive fluids. 
 By their action, the various ingredients of the alimentary mass are 
 successively reduced to a fluid condition, and are taken up by the 
 vessels of the intestinal mucous membrane. 
 
 The action which is exerted upon the food by the digestive 
 fluids is not that of a simple chemical solution. It is a transforma- 
 tion, by which the ingredients of the food are altered in character 
 at the same time that they undergo the process of liquefaction. 
 The active agent in producing this change is in every instance an 
 organic matter, which enters as an ingredient into the digestive 
 fluid; and which, by coming in contact with the food, exerts upon 
 it a catalytic action, and transforms its ingredients into other sub- 
 stances. It is these newly formed substances which are finally 
 absorbed by the vessels, and mingled with the general current of 
 the circulation. 
 
 In our study of the process of digestion, the different digestive 
 fluids will be examined separately, and their action on the aliment- 
 ary substances in the different regions of the digestive apparatus 
 successively investigated. 
 
MASTICATION. 89 
 
 MASTICATION. 
 
 In the first division of the alimentary canal, viz., the mouth, the 
 food undergoes simultaneously two different operations, viz., mas- 
 tication and insalivation. Mastication consists in the cutting and 
 trituration of the food by the teeth, by the action of which it is 
 reduced to a state of minute subdivision. This process is entirely 
 a mechanical one. It is necessary, in order to prepare the food for 
 the subsequent action of the digestive fluids. As this action is 
 chemical in its nature, it will be exerted more promptly and effi- 
 ciently if the food be finely divided than if it be brought in con- 
 tact with the digestive fluids in a solid mass. This is always the 
 case when a solid body is subjected to the chemical action of a 
 solvent fluid ; since, by being broken up into minute particles, it 
 offers a larger surface to the contact of the fluid, and is more readily 
 attacked and dissolved or decomposed by it. 
 
 In the structure of the teeth, and their physiological action, there 
 are certain marked differences, corresponding with the habits of the 
 animal, and the kind of food upon which it subsists. In fish and 
 serpents, in which the food is swallowed entire, and in which the 
 process of digestion, accordingly, is comparatively slow, the teeth 
 are simply organs of prehension. They have generally the form 
 of sharp, curved spines, with their points set backward (Fig. 19), 
 and arranged in a double or triple row 
 about the edges of the jaws, and sometimes ^^?!^ 
 
 covering the mucous surfaces of the mouth, 
 tongue, and palate. They serve merely to 
 retain the prey, and prevent its escape, 
 after it has been seized by the animal. In 
 
 .1 • n 1 J.1 J? Skull op Rattlesnake. (After 
 
 the carnivorous quadrupeds, as those of Achiiie-Eichard.) 
 the dog and cat kind, and other similar 
 
 families, there are three different kinds of teeth adapted to different 
 mechanical purposes. (Fig. 20.) First, the incisors, twelve in num- 
 ber, situated at the anterior part of the jaw, six in the superior, 
 and six in the inferior maxilla, of flattened form, and placed with 
 their thin edges running from side to side. The incisors, as their 
 name indicates, are adapted for dividing the food by a cutting 
 motion, like that of a pair of shears. Behind them come the canine 
 teeth, or tusks, one on each side of the upper and under jaw. 
 These are long, curved, conical, and pointed ; and are used as 
 
90 
 
 DIGESTION. 
 
 weapons of offence, and for laying hold of and retaining tlie prey. 
 Lastly, the molars, eight or more in number on each side, are 
 
 larger and broader than the incis- 
 ors, and provided with serrated 
 edges, each presenting several sharp 
 points, arranged generally in a di- 
 rection parallel with the line of the 
 jaw. In these animals, mastication 
 is very imperfect, since the food is 
 not ground up, but only pierced 
 and mangled by the action of the 
 teeth before being swallowed into 
 the stomach. In the herbivora, on 
 the other hand, the incisors are pre- 
 sent only in the lower jaw in the ruminating animals, though in 
 the horse they are found in both the upper and lower maxilla (Fig. 
 
 Skull of Polar Bear. Anterior view 
 showing incisors and canines. 
 
 Fig. 21. 
 
 Skull of the Horse. 
 
 Fig. 22. 
 
 21). They are used merely for cutting off the bundles of grass or 
 herbage, on which the animal feeds. The canines are either absent 
 or only slightly developed, and the real process of 
 mastication is performed altogether by the molars. 
 These are large and thick (Fig. 22), and present a 
 broad, flat surface, diversified by variously folded 
 and projecting ridges of enamel, with shallow 
 grooves, intervening between them. By the lateral 
 rubbing motion of the roughened surfaces against 
 each other, the food is effectually comminuted and 
 reduced to a pulpy mass. 
 
 In the human subject, the teeth combine the 
 
 Molar Tooth of the 
 Horse. Grinding sur- 
 face. 
 
MASTICATION. 
 
 91 
 
 In- 
 
 human Teeth — Upper Jaw. — a. Incisors. 6. Canines. 
 Anterior molars, d. Posterior molars. 
 
 characters of those of the carnivora and the herbivora. (Fig. 23.) 
 The incisors (a), four in 
 
 number in each jaw, have, ^ig- 23. 
 
 as in other instances, a 
 cuttingedge running from 
 side to side. The canines 
 (&), which are situated 
 immediately behind the 
 former, are much less 
 prominent and pointed 
 than in the carnivora, and 
 differ less in form from 
 the incisors on the one 
 hand, and the first molars 
 on the other. The molars, 
 again (c, d\ are thick and 
 strong, and have compa- 
 ratively flat surfaces, like those of the herbivora ; but instead of 
 presenting curvilinear ridges, are covered with more or less conical 
 eminences, like those of the carnivora. In the human subject, 
 therefore, the teeth are evidently adapted for a mixed diet, consist- 
 ing of both animal and vegetable food. Mastication is here as 
 perfect as it is in the herbivora, though less prolonged and labori- 
 ous ; for the vegetable substances used by man, as already remarked, 
 are previously separated to a great extent from their impurities, 
 and softened by cooking; so that they do not require, for their mas- 
 tication, so extensive and powerful a triturating apparatus. Finally, 
 animal substances are more completely masticated in the human 
 subject than they are in the carnivora, and their digestion is accord- 
 ingly completed with greater rapidity. 
 
 We can easily estimate, from the facts above stated, the great 
 importance, to the digestive process, of a thorough preliminary 
 mastication. If the food be hastily swallowed in undivided masses, 
 it must remain a long time undissolved in the stomach, where it 
 will become a source of irritation and disturbance ; but if reduced 
 beforehand, by mastication, to a state of minute subdivision, it is 
 readily attacked by the digestive fluids, and becomes speedily and 
 completely liquefied. 
 
92 
 
 DIGESTION". 
 
 SALIVA. 
 
 At the same time that the food is masticated, it is mixed in the 
 cavity of the mouth with the first of the digestive fluids, viz., the 
 saliva. Human saliva, as it is obtained directly from the buccal 
 cavity, is a colorless, slightly viscid and alkaline fluid, with a spe- 
 cific gravity of 1005. When first discharged, it is frothy and 
 opaline, holding in suspension minute, whitish flocculi. On being 
 allowed to stand for some hours in a cylindrical glass vessel, an 
 opaque, whitish deposit collects at the bottom, while the supernatant 
 fluid becomes clear. The deposit, when examined by the micro- 
 scope (Fig. 24), is seen to 
 consist of abundant epithe- 
 lium scales from the internal 
 surface of the mouth, de- 
 tached by mechanical irrita- 
 tion, minute, roundish, gra- 
 nular, nucleated cells, appa- 
 rently epithelium from the 
 mucous follicles, a certain 
 amount of granular matter, 
 and a few oil-globules. The 
 supernatant fluid has a faint 
 bluish tinge, becomes slightly 
 opalescent by boiling, and 
 the addition of nitric acid. 
 Alcohol in excess, causes the 
 precipitation of abundant 
 whitish flocculi. According to Bidder and Schmidt,^ the composi- 
 tion of saliva is as follows : — 
 
 Buccal asd Glandulab Epithelium, with Granular 
 Matter and Oil-globules ; deposited as sediment from 
 human saliva. 
 
 CoMPOsiTiox OF Saliva. 
 
 Water 
 
 Organic matter ...... 
 
 Sulpho-cyanide of potassium . . . . 
 Phosphates of soda, lime, and magnesia . 
 Chlorides of sodium and potassium . 
 Mixture of epithelium . . . • . . 
 
 995.16 
 1.34 
 
 0.06 
 .98 
 .84 
 
 1.62 
 
 1000.00 
 The organic substance present in the saliva has been occasionally 
 
 ' Verdaunngsssefte und Stoffwechsel. Leipzig, 1852. 
 
SALIVA. 93 
 
 known by the name of piyaline. It is coagulable by alcohol, but 
 not by a boiling temperature. A very little albumen is also pre- 
 sent, mingled with the ptyaline, and produces the opalescence 
 which appears in the saliva when raised to a boiling temperature. 
 The sulpho-cyanogen may be detected by a solution of chloride of 
 iron, which produces the characteristic red color of sulpho-cyanide 
 of iron. The alkaline reaction of the saliva varies in intensity 
 during the day, but is nearly always sufficiently distinct. 
 
 The saliva is not a simple secretion, but a mixture of four dis- 
 tinct fluids, which differ from each other in the source from which 
 they are derived, and in their physical and chemical properties. 
 These secretions are, in the human subject, first, that of the parotid 
 gland ; second, that of the submaxillary ; third, that of the sub- 
 lingual; and fourth, that of the mucous follicles of the mouth. 
 These different fluids have been comparatively studied, in the 
 lower animals, by Bernard, Frerichs, and Bidder and Schmidt. 
 The parotid saliva is obtained in a state of purity from the dog 
 by exposing the duct of Steno where it crosses the masseter muscle, 
 and introducing into it, through an artificial opening, a fine silver 
 canula. The parotid saliva then runs directly from its external 
 orifice, without being mixed with that of the other salivary glands. 
 It is clear, limpid, and watery, without the slightest viscidity, and 
 has a faintly alkaline reaction. The submaxillary saliva is ob- 
 tained in a similar manner, by inserting a canula into Wharton's 
 duct. It differs from the parotid secretion, so far as its physical 
 properties are concerned, chiefly in possessing a well-marked vis- 
 cidity. It is alkaline in reaction. The sublingual saliva is also 
 alkaline, colorless, and transparent, and possesses a greater degree 
 of viscidity than that from the submaxillary. The mucous secre- 
 tion of the follicles of the mouth, which forms properly a part of 
 the saliva, is obtained by placing a ligature simultaneously on 
 Wharton's and Steno's ducts, and on that of the sublingual gland, 
 so as to shut out from the mouth all the glandular salivary secre- 
 tions, and then collecting the fluid secreted by the buccal mucous 
 membrane. This fluid is very scanty, and much more viscid than 
 either of the other secretions ; so much so, that it cannot be poured 
 out in drops when received in a glass vessel, but adheres strongly 
 to the surface of the glass. 
 
 According to Bernard,^ the principal distinction between these 
 
 ' Le(;ons de Physiologie Experimentale, Paris, 1856, p. 93. 
 
^4 DIGESTION. 
 
 different salivary fluids resides in the character of the organic 
 matter peculiar to each one. The organic ingredient of the parotid 
 saliva is small in quantity, perfectly fluid, and analogous in some 
 respects to albumen, since it coagulates by a boiling temperature. 
 That of the submaxillary is moderately viscid, and has a tendency 
 to solidify or gelatinize on cooling ; while that of the sublingual 
 and mucous secretions is excessively viscid, but does not gelatinize 
 at a low temperature. 
 
 Tlie saliva proper consists, therefore, of a nearly homogeneous 
 mixture of all these different secretions ; of which that from the 
 parotid is the most abundant, tbat of the sublingual and of the 
 mucous follicles of the mouth the least so. Bidder and Schmidt 
 obtained, from one of the parotid glands of the dog, one hundred 
 and thirty-six grains of fluid in an hour; from the submaxillary, 
 eighty-seven grains ; and from the mucous follicles of the mouth, 
 after ligature of both Wharton's and Steno's ducts, thirty-one 
 grains. The saliva, as a whole, is not secreted with uniform 
 rapidity at all times. While fasting, and while the tongue and 
 jaws are at rest, it is supplied in but small quantity, just sufficient 
 to keep the mucous membrane of the mouth moist and pliable. 
 - Any movement of the jaws, however, increases the rapidity of its 
 flow. It is still more powerfully stimulated by the introduction of 
 food, particularly that which has a decided taste, or which requires 
 an active movement of the jaws for its mastication. The saliva is 
 then poured out in abundance, and continues to be rapidly secreted 
 until the food is masticated and swallowed. 
 
 A very curious fact has been observed by M. Colin, Professor of 
 Anatomy and Physiology at the Veterinary School of Alfort,' viz., 
 that in the horse and ass, as well as in the cow and other ruminat- 
 ing animals, the parotid glands of the two opposite sides, during 
 mastication, are never in active secretion at the same time; but 
 that they alternate with each other, one remaining quiescent while 
 the other is active, and vice versa. In these animals, mastication is 
 said to be unilateral, that is, when the animal commences feeding 
 or ruminating the food is triturated, for fifteen minutes or more, by 
 the molars of one side only. It is then changed to the opposite 
 side; and for the next fifteen minutes mastication is performed by 
 the molars of that side only. It is then changed back again, and 
 so on alternately, so that the direction of the lateral movements of 
 
 ' Traite de Physiologie Comparee, Paris, 1854, p. 468. 
 
SALIVA. 95 
 
 the jaw may be reversed many times during the course of a meal. 
 By establishing a salivary fistula simultaneously on each side, it is 
 found that the flow of saliva corresponds with the direction of the 
 masticatory movement. When the animal masticates on the right 
 side, it is the right parotid which secretes actively, while but little 
 saliva is supplied by the left ; when mastication is on the left side, 
 the left parotid pours out an abundance of fluid, while the right is 
 nearly inactive. It is probable, however, that this alternation of 
 function does not exist, to the same extent at least, in man and the 
 carnivora, in whom mastication is performed very nearly on both 
 sides at once. 
 
 Owing to the variations in the rapidity of its secretion, and also 
 to the fact that it is not so readily excited by artificial means as 
 by the presence of food, it becomes somewhat difiicult to estimate 
 the total quantity of saliva secreted daily. The first attempt to do 
 so was made by Mitscherlich,' who collected from two to three ounces 
 in twenty-four hours from an accidental salivary fistula of Steno's 
 duct in the human subject ; from which it was supposed that the 
 total amount secreted by all the glands was from ten to twelve ounces 
 daily. As this man was a hospital patient, however, and suffering 
 from constitutional debility, the above calculation cannot be re-, 
 garded as an accurate one, and accordingly Bidder and Schmidt^ 
 make a higher estimate. One of these observers, in experimenting 
 upon himself, collected from the mouth in one hour, without using 
 any artificial stimulus to the secretion, 1500 grains of saliva ; and 
 calculates, therefore, the amount secreted daily, making an allow- 
 ance of seven hours for sleep, as not far from 25,000 grains, or 
 about three and a half pounds avoirdupois. 
 
 On repeating this experiment, however, we have not been able to 
 collect from the mouth, without artificial stimulus, more than 556 
 grains of saliva per hour. This quantity, however, may be greatly 
 increased by the introduction into the mouth of any smooth unirri- 
 tating substance, as glass beads or the like ; and during the masti- 
 cation of food, the saliva is poured out in very much greater abund- 
 ance. The very sight and odor of nutritious food, when the appetite 
 is excited, will stimulate to a remarkable degree the flow of saliva; 
 and, as it is often expressed, "bring the water into the mouth." 
 Any estimate, therefore, of the total quantity of saliva, based on 
 the amount secreted in the intervals of mastication, would be a very 
 
 « Simon's Chemistry of Man. Phila. ed., 1846, p. 295. ^ Op. cit., p. 14. 
 
96 DIGESTION. 
 
 imperfect one. We may make a tolerably accurate calculation, 
 however, by ascertaining how much, is really secreted during a 
 meal, over and above that which is produced at other times. We 
 have found, for example, by experiments performed for this pur- 
 pose, that wheaten bread gains during complete mastication 55 per 
 cent, of its weight of saliva ; and that fresh cooked meat gains, 
 under the same circumstances, 48 per cent, of its weight. We have 
 already seen that the daily allowance of these two substances, for a 
 man in full health, is 19 ounces of bread, and 16 ounces of meat. 
 The quantity of saliva, then, required for the mastication of these 
 two substances, is, for the bread 4,572 grains, and for the meat 3,360 
 grains. If we now calculate the quantity secreted between meals 
 as continuing for 22 hours at 556 grains per hour, we have: — 
 
 Saliva required for mastication of bread = 4572 grains. 
 " " " " " meat = 3360 " 
 
 " secreted in intervals of meals = 12232 " 
 
 Total quantity in twenty-four hours = 20164 grains ; 
 
 or rather less than 3 pounds avoirdupois. 
 
 The most important question, connected with this subject, relates 
 to ihQ function of the saliva in the digestive process. A very remarka- 
 ble property of this fluid is that which was discovered by Leuchs 
 in Germany, viz., that it possesses the power of converting boiled 
 starch into sugar, if mixed with it in equal proportions, and kept 
 for a short time at the temperature of 100° F. This phenomenon 
 is one of catalysis, in which the starch is transformed into sugar by 
 simple contact with the organic substance contained in the saliva. 
 This organic substance, according to the experiments of Mialhe,^ 
 may even be precipitated by alcohol, and kept in a dry state for an 
 indefinite length of time without losing the power of converting 
 starch into sugar, when again brought in contact with it in a state 
 of solution. 
 
 This action of ordinary human saliva on boiled starch takes place 
 sometimes with great rapidity. Traces of glucose may occasionally 
 be detected in the mixture in one minute after the two substances 
 have been brought in contact; and we have even found that starch 
 paste, introduced into the cavity of the mouth, if already at the 
 temperature of 100° F., will yield traces of sugar at the end of half 
 a minute. The rapidity, however, with which this action is mani- 
 
 ' Chimie appliquee a la Physiologie et a la Therapeutique, Paris, 1856, p. 43. 
 
SALIVA. 97 
 
 fested, varies very mucli, as was formerly noticed by Lebraann, at 
 different times ; owing, in all probability, to the varying constitution 
 of the saliva itself. It is often impossible, for example, to find any 
 evidences of sugar, in the mixture of starch and saliva, under five, 
 ten, or fifteen minutes ; and it is frequently a longer time than this 
 before the whole of the starch is completely transformed. Even 
 when the conversion of the starch commences very promptly, it is 
 often a long time before it is finished. If a thin starch paste, for 
 example, which contains no traces of sugar, be taken into the mouth 
 and thoroughly mixed with the buccal secretions, it will often, as 
 already mentioned, begin to show the reaction of sugar in the course 
 of half a minute ; but some of the starchy matter still remains, and 
 will continue to manifest its characteristic reaction with iodine, for 
 fifteen or twenty minutes, or even half an hour. 
 
 The above action of the saliva on starch, according to the experi- 
 ments of Magendie, Bernard, Bidder and Schmidt, &c., does not 
 reside in either the parotid, submaxillary or mucous secretions 
 taken separately ; but only in the mixed saliva, as it comes from 
 the cavity of the mouth. The submaxillary and mucous secretions, 
 however, taken together, produce the change ; though neither of them 
 has any effect alone, nor even when mixed artificially with the saliva 
 of the parotid. 
 
 It was supposed, when this property of converting starch into 
 sugar was first discovered to exist in the saliva, that it constituted 
 the true physiological action of the secretion, and that the function 
 of the saliva was, in reality, the digestion and liquefaction of starchy 
 substances. It was very soon noticed, however, by the French 
 observers, that this property of the saliva was rather an accidental 
 than an essential one ; and that, although starchy substances are 
 really converted into sugar, if mixed with saliva in a test-tube, yet 
 they are not affected by it to the same degree in the natural process 
 of digestion. We have already mentioned above the extremely 
 variable activity of the saliva, in this respect, at different times ; 
 and it must be recollected, also, that in digestion the food is not 
 retained in the cavity of the mouth, but passes at once, after mas- 
 tication, into the stomach. Several German observers, as Frerichs, 
 Jacubowitsch, Bidder, and. Schmidt, maintained at first that the 
 saccharine conversion of starch, after being commenced in the 
 mouth, might be, and actually was, completed in the stomach. We 
 have convinced ourselves, however, by frequent experiments, that 
 this is not the case. If a dog, with a gastric fistula, be fed with a 
 7 
 
98 DIGESTIOISr. 
 
 mixture of meat and boiled starch, and portions of the fluid con- 
 tents of the stomacli withdrawn afterward through the fistula, 
 the starch is easily recognizable by its reaction with iodine for ten, 
 fifteen, and twenty minutes afterward. In forty-five minutes, it is 
 diminished in quantity, and in one hour has usually altogether dis- 
 appeared ; but no sugar is to be detected at any time. Sometimes 
 the starch disappears more rapidly than this ; but at no time, accord- 
 ing to our observations, is there any indication of the presence of 
 sugar in the gastric fluids. Bidder and Smith have also concluded, 
 from subsequent investigations,^ that the first experiments performed 
 Tinder their direction by Jacubowitsch were erroneous; and it is 
 now acknowledged by them, as well as by the Frenchi observers, 
 that sugar cannot be detected in the stomach, after the introduction 
 of starch, in any form or by any method. In the ordinary process 
 of digestion, in fact, starcby matters do not remain long enough in 
 the mouth to be altered by the saliva, but pass at once into the sto- 
 mach. Here they meet with, the gastric fluids, which become min- 
 gled with them, and prevent the change which would otherwise be 
 effected by the saliva. We have found that the gastric juice will 
 interfere, in this manner, with the action of the saliva in the test- 
 tube, as well as in the stomach. If two mixtures be made, one of 
 starch and saliva, the other of starch, saliva, and gastric juice, and 
 botb kept for fifteen minutes at the temperature of 100° F., in the 
 first mixture the starch will be promptly converted into sugar, while 
 in the second no such change will take place. The above action, 
 therefore, of saliva on starch, though a curious and interesting pro- 
 perty, has no significance as to its physiological function, since it 
 does not take place in the natural digestive process. We shall see 
 hereafter that there are other means provided for the digestion of 
 starchy matters, altogether independent of the action of the saliva. 
 The true function of the saliva is altogether a physical one. Its 
 action is simply to moisten the food and facilitate its mastication, 
 as well as to lubricate the triturated mass, and assist its passage 
 down the oesophagus. Food which is hard and dry, like crusts, 
 crackers, &c,, cannot be masticated and swallowed with readiness 
 unless moistened by some fluid. If the saliva, therefore, be prevented 
 from entering the cavity of the mouth, its loss does not interfere 
 directly with the chemical changes of the food in digestion, but only 
 with its mechanical preparation. This is the result of direct experi- 
 
 " Op. cit., p. 26. 
 
SALIVA. 99 
 
 ments performed by various observers. Bidder and Schmidt/ after 
 tying Steno's duct, together with the common duct of the sub- 
 maxillary and sublingual glands on both sides in the dog, found 
 that the immediate effect of such an operation was "a remarkable 
 diminution of the fluids which exude upon the surfaces of the mouth; 
 so that these surfaces retained their natural moisture only so long 
 as the mouth was closed, and readily became dry on exposure to 
 contact with the air. Accordingly, deglutition became evidently 
 difficult and laborious, not only for dry food, like bread, but even 
 for that of a tolerably moist consistency, like fresh meat. The ani- 
 mals also became very thirsty, and were constantly ready to drink," 
 
 Bernard^ also found that the only marked effect of cutting off" 
 the flow of saliva from the mouth was a difficulty in the mechani- 
 cal processes of mastication and deglutition. He first administered 
 to a horse one pound of oats, in order to ascertain the rapidity with 
 which mastication would naturally be accomplished. The above 
 quantity of grain was thoroughly masticated and swallowed at the 
 end of nine minutes. An opening had been previously made 
 in the oesophagus at the lower part of the neck, so that none of the 
 food reached the stomach; but each mouthful, as it passed down the 
 oesophagus, was received at the oesophageal opening and examined 
 by the experimenter. The parotid duct on each side of the face 
 was then divided, and another pound of oats given to the animal. 
 Mastication and deglutition were both found to be immediately 
 retarded. The alimentary masses passed down the oesophagus at 
 longer intervals, and their interior was no longer moist and pasty, 
 as before, but dry and brittle. Finally, at the end of twenty-five 
 minutes, the animal had succeeded in masticating and swallowing 
 only about three-quarters of the quantity which he had previously 
 disposed of in nine minutes. 
 
 It appears, also, from the experiments of Magendie, Bernard, and 
 Lassaigne, on horses and cows, that the quantity of saliva absorbed 
 by the food during mastication is in direct proportion to its hard- 
 ness and dryness, but has no particular relation to its chemical 
 qualities. These experiments were performed as follows : The oeso- 
 phagus was opened at the lower part of the neck, and a ligature 
 placed upon it, between the wound and the stomach. The animal 
 was then supplied with a previously weighed quantity of food, and 
 this, as it passed out by the oesophageal opening, was received into 
 
 ' Op. cit., p. 3. 
 
 ^ Lemons de Physiologie Experimeutale, Paris, 1856, p. 146. 
 
100 DIGESTION. 
 
 appropriate vessels and again weighed. The difference in weight, 
 before and after swallowing, indicated the quantity of saliva absorbed 
 by the food. The following table gives the results of some of Las- 
 saigne's experiments,' performed upon a horse : — 
 
 Kind of Food employed. Quantity of Saline absokbed. 
 
 For 100 parts of liay there were absorbed 400 parts saliva. 
 
 " barley meal " 186 " 
 
 " oats " 113 " 
 
 " green stalks and leaves " 49 " 
 
 It is evident, from the above facts, that the quantity of saliva 
 produced has not so much to do with the chemical character of the 
 food as with its physical condition. When the food is dry and 
 hard, and requires much mastication, the saliva is secreted in 
 abundance ; when it is soft and moist, a smaller quantity of the 
 secretion is poured out; and finally, when the food is taken in a 
 fluid form, as soup or milk, or reduced to powder and moistened 
 artificially with a very large quantity of water, it is not mixed at 
 all with the saliva, but passes at once into the cavity of the stomach. 
 The abundant and watery fluid of the parotid gland is most useful 
 in assisting mastication; while the glairy and mucous secretion of 
 the submaxillary gland and the muciparous follicles serve to lubri- 
 cate the exterior of the triturated mass, and facilitate its passage 
 through the oesophagus. 
 
 By the combined operation of the two processes which the food 
 undergoes in the cavity of the mouth, its preliminary preparation 
 is accomplished. It is triturated and disintegrated by the teeth, 
 and, at the same time, by the movements of the jaws, tongue, and 
 cheeks, it is intimately mixed with the salivary fluids, until the 
 whole is reduced to a soft, pasty mass, of the same consistency 
 throughout. It is then carried backward by the semi-involuntary 
 movements of the tongue into the pharynx, and conducted by the 
 muscular contractions of the oesophagus into the stomach. 
 
 THE GASTEIO JUICE, AND STOMACH DIGESTION. 
 
 The mucous membrane of the stomach is distinguished by its 
 great vascularity and the abundant glandular apparatus with which 
 it is provided. Its entire thickness is occupied by certain glandular 
 organs, the gastric tubules or follicles, which are so closely set as to 
 leave almost no space between them except what is required for the 
 
 ' Comptes Rendus, vol. xxi. p. 362. 
 
THE GASTRIC JUICE, AND STOMACH DIGESTION. 101 
 
 capillary bloodvessels. The free surface of the gastric mucous 
 membrane is not smooth, but is raised in minute ridges and pro- 
 jecting eminences. In the cardiac portion (Fig. 25), these ridges 
 are reticulated with each other, so as to include between them 
 
 Fig. 25. 
 
 Fig. 26. 
 
 Fig. 27. 
 
 Fig. 25. Free surface of G.vstric Macous Me.mbrane, viewed from above ; from Pig's Stomach, Car- 
 diac portion. Magnified 70 diameters. 
 
 Fig. 26. Free surface of Gastric Mococts Me.mbrane, viewed in vertical section; from Pig's 
 Stomacli, Pyloric portion. Magnified 420 diameters. 
 
 polygonal interspaces, each of which is encircled by a capillary 
 network. In the pyloric portion (Fig. 26), these eminences are 
 more or less pointed and coni- 
 cal in form, and generally 
 flattened from side to side. 
 They contain each a capillary 
 bloodvessel, which returns 
 upon itself in a loop at the 
 extremity of the projection, 
 and communicates freely with 
 adjacent vessels. The gastric 
 follicles are very different in 
 different parts of the stomach. 
 In the pyloric portion (Fig. 
 27), they are nearly straight, 
 simple tubules, ^\^ of an inch 
 in diameter, easily separated 
 from each other, lined with 
 glandular epithelium, and ter- 
 minating in cul-de-sacs at the under surface of the mucous mem- 
 
 Mncous Membrane of Pig's Stomach, from Pyloric 
 portion; vertical section; showing gastric tubules, 
 and, at a, a closed follicle. Magnified 70 diameters. 
 
102 
 
 DIGESTION. 
 
 Gastric Tdedles from Pig's Stomach, Pyloric por- 
 tion, showing their C^ecal Extremities. At a, a cylin- 
 drical cast of epithelium, pressed out from a tubule, 
 showing the size of its cavity. 
 
 brane. They are sometimes slightly branched, or provided with 
 one or two rounded diverticula, a short distance above their ter- 
 mination. They open on the 
 free surface of the mucous 
 membrane, in the interspaces 
 between the projecting folds 
 or villi. Among these tubular 
 glandules there is also found, 
 in the gastric mucous mem- 
 brane, another kind of glandu- 
 lar organ, consisting of closed 
 follicles, similar to the solitary 
 glands of the small intestine. 
 These follicles, which are not 
 very numerous, are seated in 
 the lower part of the mucous 
 membrane, and enveloped by 
 the c£ecal extremities of the 
 tubules. (Fig. 27, a.) 
 
 In the cardiac portion of 
 the stomach, the tubules are very wide in the superficial part of 
 the mucous membrane, and lined with large, distinctly marked 
 
 cylinder epithelium cells. (Fig. 
 29.) In the deeper parts of 
 the membrane they become 
 branched and considerably 
 reduced in size. From the 
 point where the branching 
 takes place to where they 
 terminate below in cul-de sacs, 
 they are lined with small 
 glandular epithelium cells, 
 and closely bound together 
 by intervening areolar tissue, 
 so as to present somewhat 
 the appearance of compound 
 glandules. 
 
 The bloodvessels which 
 come up from the submucous 
 layer of areolar tissue form a 
 close plexus around all these glandules, and provide the mucous 
 
 Gastric Tubules from Pig's Stomach ; Cardiac 
 portion. At a, a large tubule dividing into two small 
 ones. b. Portion of a tubule, seen endwise, c. Its 
 central cavity. 
 
THE GASTEIC JUICE, AND STOMACH DIGESTION. 103 
 
 membrane with an abundant supply of blood, both for the purposes 
 of secretion and absorption. 
 
 That part of digestion which takes place in the stomach has 
 always been regarded as nearly, if not quite, the most important 
 part of the whole process. The first observers who made any 
 approximation to a correct idea of gastric digestion were Reaumur 
 and Spallanzani, who showed by various methods that the reduction 
 and liquefaction of the food in the stomach could not be owing to a 
 mere contact with the gastric mucous membrane, or to compression 
 by the muscular walls of the organ ; but that it must be attributed 
 to a digestive fluid secreted by the mucous membrane, which pene- 
 trates the food and reduces it to a fluid form. They regarded this 
 process as a simple chemical solution, and considered the gastric 
 juice as a universal solvent for all alimentary substances. They 
 succeeded even in obtaining some of this gastric juice, mingled 
 probably with many impurities, by causing the animals upon which 
 they experimented to swallow sponges attached to the ends of 
 cords, by which they were afterwards withdrawn, and the fluids, 
 which they had absorbed, expressed and examined. 
 
 The first decisive experiments on this point, however, were those 
 performed by Dr. Beaumont, of the U. S. Army, on the person of 
 Alexis St. Martin, a Canadian boatman, who had a permanent gas- 
 tric fistula, accidentally produced by a gunshot wound. The musket, 
 which was loaded with buckshot at the time of the accident, was 
 discharged at the distance of a few feet from St. Martin's body, in 
 such a manner as to tear away the integument at the lower part of 
 the left chest, open the pleural cavity, and penetrate, through the 
 lateral portion of the diaphragm, into the great pouch of the stomach. 
 After the integument and the pleural and peritoneal surfaces had 
 united and cicatrized, there remained a permanent opening, of about 
 four-fifths of an inch in diameter, leading into the left extremity of 
 the stomach, which was usually closed by a circular valve of pro- 
 truding mucous membrane. This valve could be readily depressed 
 at any time, so as to open the fistula and allow the contents of the 
 stomach to be extracted for examination. 
 
 Dr. Beaumont experimented upon this person at various intervals 
 from the year 1825 to 1832.^ He established during the course of 
 his examinations the following important facts : First, that the ac. 
 tive agent in digestion is an acid fluid, secreted by the walls of the 
 
 ' Experiments and Observations on tlie Gastric Juice. Boston, 1834. 
 
10^ DIGESTION", 
 
 stomach ; secondly, that this fluid is poured out by the glandular 
 walls of the organ only during digestion, and under the stimulus of 
 the food ; and finally, that it will exert its solvent action upon the 
 food outside the body as well as in the stomach, if kept in glass 
 phials upon a sand bath, at the temperature of 100° F. He made 
 also a variety of other interesting investigations as to the effect 
 of various kinds of stimulus on the secretion of the stomach, the 
 rapidity with which the process of digestion takes place, the com- 
 parative digestibility of various kinds of food, &c. &c. 
 
 Since Dr. Beaumont's time it has been ascertained that similar 
 gastric fistulee may be produced at will on some of the lower animals 
 by a simple operation ; and the gastric juice has in this way been 
 obtained, usually from the dog, by Blondlot, Schwann, Bernard, 
 Lehmann and others. The simplest and most expeditious mode 
 of doing the operation is the best. An incision should be made 
 through the abdominal parietes in the median line, over the great 
 curvature of the stomach. The anterior wall of the organ is then 
 to be seized with a pair of hooked forceps, drawn out at the external 
 wound, and opened with the point of a bistoury. A short silver 
 canula one-half to three-quarters of an inch in diameter, armed at 
 each extremity with a narrow projecting rim or flange, is then in- 
 serted into the wound in the stomach, the edges of which are fast- 
 ened round the tube with a ligature in order to prevent the escape 
 of the gastric fluids into the peritoneal cavity. The stomach is then 
 returned to its place in the abdomen, and the canula allowed to re- 
 main with its external flange resting upon the edges of the wound 
 in the abdominal integuments, which are to be drawn together by 
 sutures. The animal may be kept perfectly quiet, during the ope- 
 ration, by the administration of ether or chloroform. In a few 
 days the ligatures come awa}^, the wounded peritoneal surfaces are 
 united with each other, and the canula is retained in a permanent 
 gastric fistula ; being prevented by its flaring extremities both from 
 falling out of the abdomen and from being accidentally pushed into 
 the stomach. It is closed externally by a cork, which may be with- 
 drawn at pleasure, and the contents of the stomach withdrawn for 
 examination. 
 
 Experiments conducted in this manner confirm, in the main, the 
 results obtained by Dr. Beaumont. Observations of this kind are 
 in ^ome respects, indeed, more satisfactory when made upon the 
 lower animals, than upon the human subject; since animals are en- 
 tirely under the control of the experimenter, and all sources of 
 
THE GASTRIC JUICE, AND STOMACH DIGESTION". 105 
 
 deception or mistake are avoided, while the investigation is, at the 
 same time, greatly facilitated by the simple character of their food. 
 The gastric juice, like the saliva, is secreted in considerable 
 quantity only under the stimulus of recently ingested food. Dr. 
 Beaumont states that it is entirely absent during the intervals of 
 digestion ; and that the stomach at that time contains no acid fluid, 
 but only a little neutral or alkaline mucus. He was able to obtain 
 a sufficient quantity of gastric juice for examination, by gently irri- 
 tating the mucous membrane with a gum-elastic catheter, or the end 
 of a glass rod, and by collecting the secretion as it ran in drops 
 from the fistula. On the introduction of food, he found that the 
 mucous membrane became turgid and reddened, a clear acid fluid 
 collected everywhere in drops underneath the layer of mucus lin- 
 ing the walls of the stomach, and was soon poured out abundantly 
 into its cavity. We have found, however, that the rule laid down 
 by Dr. Beaumont in this respect, though correct in the main, is not 
 invariable. The truth is, the irritability of the gastric mucous 
 membrane, and the readiness with which the flow of gastric juice 
 may be excited, varies considerably in different animals ; even in 
 those belonging to the same species. In experimenting with gastric 
 fistulae on different dogs, for example, we have found in one instance, 
 like Dr. Beaumont, that the gastric juice was always entirely absent 
 in the intervals of digestion ; the mucous membrane then present- 
 ing invariably either a neutral or slightly alkaline reaction. In 
 this animal, which was a perfectly healthy one, the secretion could 
 not be excited by any artificial means, such as glass rods, metallic 
 catheters, and the like ; but only by the natural stimulus of ingested 
 food. We have even seen tough and indigestible pieces of tendon, 
 introduced through the fistula, expelled again in a few minutes, one 
 after the other, without exciting the flow of a single drop of acid 
 fluid; while pieces of fresh meat, introduced in the same way, pro- 
 duced at once an abundant supply. In other instances, on the con- 
 trary, the introduction of metallic catheters, &c.j into the empty 
 stomach has produced a scanty flow of gastric juice ; and in experi- 
 menting upon dogs that have been kept without food during various 
 periods of time and then killed by section of the medulla oblongata, 
 we have usually, though not always, found the gastric mucous mem- 
 brane to present a distinctly acid reaction, even after an abstinence 
 of six, seven, and eight days. There is at no time, however, under 
 these circumstances, any considerable amount of fluid present in 
 
106 DIGESTION. 
 
 the stomacli ; but onl}^ just sufficient to moisten the gastric mucous 
 membrane, and give it an acid reaction. 
 
 The gastric juice, which is obtained by irritating the stomach 
 with a metallic catheter, is clear, perfectly colorless, and acid in 
 reaction. A sufficient quantity of it cannot be obtained by this 
 method for any extended experiments ; and for that purpose, the 
 animal should be fed, after a fast of twenty-four hours, with fresh 
 lean meat, a little hardened by short boiling, in order to coagulate 
 the fluids of the muscular tissue, and prevent their mixing with the 
 gastric secretion. No effect is usually apparent within the first five 
 minutes after the introduction of the food. At the end of that time 
 the gastric juice begins to flow ; at first slowly, and in drops. It is 
 then perfectly colorless, but very soon acquires a slight amber 
 tinge. It then begins to flow more freely, usually in drops, but 
 often running for a few seconds in a continuous stream. In this 
 way from lij to ^iiss may be collected in the course of fifteen 
 minutes. After this it becomes somewhat turbid with the debris 
 of the food, which has begun to be disintegrated ; but from this it 
 may be readily separated by filtration. After three hours, it con- 
 tinues to run freely, but has become very much thickened, and 
 even grumous in ' consistency, from the abundant admixture of 
 alimentary debris. In six hours after the commencement of diges- 
 tion it runs less freely, and in eight hours has become very scanty, 
 though it continues to preserve the same physical appearances as 
 before. It ceases to flow altogether in from nine to twelve hours, 
 according to the quantity of food taken. 
 
 For purposes of examination, the fluid drawn during the first 
 fifteen minutes after feeding should be collected, and separated by 
 filtration from accidental impurities. Obtained in this way, the 
 gastric juice is a clear, watery fluid, without any appreciable vis- 
 cidity, very distinctly acid to test paper, of a faint amber color, 
 and with a specific gravity of 1010. It becomes opalescent on 
 boiling, owing to the coagulation of its organic ingredients. The 
 following is the composition of the gastric juice of the dog, based 
 on a comparison of various analyses by Lehmann, and Bidder and 
 Schmidt: — 
 
THE GASTRIC JUICE, AND STOMACH DIGESTIOISr. 107 
 
 Composition of Gastric Juice. 
 
 Water 975.00 
 
 Organic matter ........ 15.00 
 
 Lactic acid ......... 4.78 
 
 Chloride of sodium . . . . . . . . 1.70 
 
 " " potassium . . . . • . • 1.08 
 
 " " calcium 0.20 
 
 " " ammoniura ....... 0.65 
 
 Phosphate of lime ........ 1.48 
 
 " " magnesia 0.06 
 
 " " iron 0.05 
 
 1000.00 
 
 In place of lactic acid, Bidder and Sclimidt found, in most of their 
 analyses, hydrochloric acid. Lehmann admits that a small quantity 
 of hydrochloric acid is sometimes present, but regards lactic acid as 
 much the most abundant and important of the two. Robin and 
 Verdeil also regard the acid reaction of the gastric juice as due to 
 lactic acid ; and, finally, Bernard has shown,^ by a series of well 
 contrived experiments, that the free acid of the dog's gastric juice 
 is undoubtedly the lactic ; and that the hydrochloric acid obtained 
 by distillation, is really produced by a decomposition of the 
 chlorides, which enter into the composition of the fresh juice. 
 
 The free acid is an extremely important ingredient of the gastric 
 secretion, and is, in fact, essential to its physiological properties; 
 for the gastric juice will not exert its solvent action upon the food, 
 after it has been neutralized by the addition of an alkali or an 
 alkaline carbonate. 
 
 The most important ingredient of the gastric juice, beside the 
 free acid, is its organic matter or " ferment," which is sometimes 
 known under the name of -pepsine. This name, "pepsine," was 
 originally given by Schwann to a substance which he obtained 
 from the mucous membrane of the pig's stomach, by macerating it 
 in distilled water until a putrid odor began to be developed. The 
 substance in question was precipitated from the watery infusion 
 by the addition of alcohol, and dried ; and if dissolved afterward 
 in acidulated water, it was found to exert a solvent action on boiled 
 white of Qgg. This substance, however, did not represent precisely 
 the natural ingredient of the gastric secretion, and was probably a 
 mixture of various matters, some of them the products of com- 
 mencing decomposition of the mucous membrane itself. The name 
 pepsine, if it be used at all, should be applied to the organic matter 
 
 ' Le9ons de Physiologie Experimentale, Paris, 1856, p. 396. 
 
108 
 
 DIGESTION. 
 
 wTaicTi naturally occurs in solution in the gastric juice. It is alto- 
 gether unessential, in this respect, from what source it may be 
 originally derived. It has been regarded by Bernard and others, 
 o'n somewhat insufficient grounds, as a product of the alteration of 
 the mucus of the stomach. But whatever be its source, since it is 
 always present in the secretion of the stomach, and takes an active 
 part in the performance of its function, it can be regarded in ifo 
 other light than as a real anatomical ingredient of the gastric juice, 
 and as essential to its constitution. 
 
 Pepsine is precipitated from its solution in the gastric juice by 
 absolute alcohol, and by various metallic salts, but is not affected 
 by ferrocyanide of potassium. It is precipitated also, and coagu- 
 lated by a boiling temperature; and the gastric juice, accordingly, 
 after being boiled, becomes turbid, and loses altogether its power 
 of dissolving alimentary substances. Gastric juice is also affected 
 in a remarkable manner by being mingled with Ule. We have 
 found that four to six drops of dog's bile precipitate completely 
 with 5j of gastric juice from the same animal; so that the whole of 
 the biliary coloring matter is thrown down as a deposit, and the 
 filtered fluid is found to have lost entirely its digestive power, 
 though it retains an acid reaction. 
 
 .A very singular property of the gastric juice is its inaptitude for 
 putrefaction. It may be kept for an indefinite length of time in a 
 common glass- stoppered bottle without developing any putrescent 
 odor. A light deposit generally c^ollects at the bottom, and a con- 
 fervoid vegetable growth or "mould" often shows itself in the fluid 
 
 after it has been kept for one 
 or two weeks. This growth 
 has the form of white, globular 
 masses, each of which is com- 
 posed of delicate radiating 
 branched filaments (Fig. 30) ; 
 each filament consisting of 
 a row of elongated cells, like 
 other vegetable growths of a 
 similar nature. These growths, 
 however, are not accompa- 
 nied by any putrefactive 
 changes, and the gastric juice 
 retains its acid reaction and 
 
 CONFERVOID Vegetable, growing iu the Gastric Juice itS digCStivC prOpCrticS for 
 of the Dog. The fibres have an average diameter of fi^nT-i-y- months 
 ] -7000th of an inch. -^ 
 
THE GASTRIC JUICE, AND STOMACH DIGESTION. 109 
 
 By experimenting artificially with gastric juice on various ali- 
 mentary substances, such as meat, boiled white of egg, &c., it is 
 found, as Dr. Beaumont formerly observed, to exert a solvent action 
 on these substances outside the body, as well as in the cavity of 
 the stomach. This action is most energetic at the temperature of 
 100° F. It gradually diminishes in intensity below that point, and 
 ceases altogether near 32°. If the temperature be elevated above 
 100° the action also becomes enfeebled, and is entirely suspended 
 about 160°, or the temperature of coagulating albumen. Contrary 
 to what was supposed, however, by Br. Beaumont and his predeces- 
 sors, the gastric juice is not a universal solvent for all alimentary 
 substances, but on the contrary, affects only a single class of the 
 proximate principles, viz., the albuminoid or organic substances. 
 Neither starch nor oil, when digested in it at the temperature of 
 the body, suffers the slightest chemical alteration. Fatty matters 
 are simply melted by the heat, and starchy substances are only 
 hydrated and gelatinized to a certain extent by the combined 
 influence of the warmth and moisture. Solid and semi-solid 
 albuminoid matters, however, are at once attacked and liquefied 
 by the digestive fluid. Pieces of coagulated white of egg sus- 
 pended in it, in a test-tube, become gradually softened on their 
 exterior, and their edges become pale and rounded. They grow thin 
 and transparent ; and their substance finally melts away, leaving a 
 light, scanty deposit, which collects at the bottom of the test-tube. 
 While the disintegrating process is going on, it may be almost 
 always noticed that minute, opaque spots show themselves in the 
 substance of the liquefying albumen, indicating that certain parts 
 of it are less easily attacked than the rest ; and the deposit which 
 remains at the bottom is probably also composed of some ingre- 
 dient, not soluble in the gastric juice. If pieces of fresh meat be 
 treated in the same manner, the areolar tissue entering into its com- 
 position is first dissolved, so that the muscular bundles become more 
 distinct, and separate from each other. They gradually fall apart, 
 and a little brownish deposit is at last all that remains at the bottom 
 of the tube. If the hard, adipose tissue of beef or mutton be sub- 
 jected to the same process, the walls of the fat vesicles and the 
 intervening areolar tissue, together with the capillary bloodvessels, 
 &;c., are dissolved ; while the oily matters are set free from their 
 envelops, and collect in a white, opaque layer on the surface. In 
 cheese, the casein is dissolved, and the oil set free, as above. In 
 bread, the gluten is digested, and the starch left unchanged. In 
 
110 DIGESTIOISr. 
 
 milk, the casein is first coagulated by contact with the acid gastric 
 fluids, and afterward slowly liquefied, like other albuminoid sub- 
 stances. 
 
 The time required for the complete liquefaction of these sub- 
 stances varies with the quantity of matter present, and with its state 
 of cohesion. The process is hastened by occasionally shaking up 
 the mixture, so as to separate the parts already disintegrated, and 
 bring the gastric fluid into contact with fresh portions of the 
 digestible substance. 
 
 The liquefying process which the food undergoes in the gastric 
 juice is not a sknple solution. It is a catalytic transformation, 
 produced in the albuminoid substances by contact with the or- 
 ganic matter of the digestive fluid. This organic matter acts in 
 a similar manner to that of the catalytic bodies, or "ferments," 
 generally. Its peculiarity is that, for its active operation, it re- 
 quires to be dissolved in an acidulated fluid. In common with 
 other ferments, it requires also a moderate degree of warmth ; its 
 action being checked, both by a very low, and a very high tempe- 
 rature. By its operation the albuminoid matters of the food, what- 
 ever may have been their original character, are all, without dis- 
 tinction, converted into a new substance, viz., albuminose. This 
 substance has the general characters belonging to the class of 
 organic matters. It is uncrystallizable, and contains nitrogen as 
 an ultimate element. It is precipitated, like albumen, by an excess 
 of alcohol, and by the metallic salts ; but unlike albumen, is not 
 affected by nitric acid or a boiling temperature. It is freely soluble 
 in water, and after it is once produced by the digestive process, 
 remains in a fluid condition, and is ready to be absorbed by the 
 vessels. In this way, casein, fibrin, musculine, gluten, &c., are all 
 reduced to the condition of albuminose. By experimenting as 
 above, with a mixture of food and gastric juice in test tubes, we 
 have found that the casein of cheese is entirely converted into 
 ^albuminose, and dissolved under that form. A very considerable 
 portion of raw white of egg, however, dissolves in the gastric juice 
 directly as albumen, and retains its property of coagulating by 
 heat. Soft-boiled white of egg and raw meat are principally con- 
 verted into albuminose; but at the same time, a small portion of 
 albumen is also taken up unchanged. 
 
 The above process is a true liquefaction of the albuminoid sub- 
 stances, and not a simple disintegration. If fresh meat be cut into 
 small pieces, and artificially digested in gastric juice in test tubes. 
 
THE GASTRIC JUICE, AND STOMACH DIGESTION. Ill 
 
 at 100° F., and the process assisted by occasional gentle agitation, 
 the fluid continues to take up more and more of the digestible 
 material for from eight to ten hours. At the end of that time if it 
 be separated and filtered, the filtered fluid has a distinct, brownish 
 color, and is saturated with dissolved animal matter. Its specific 
 gravity is found to have increased from 1010 to 1020 ; and on the 
 addition of alcohol it becomes turbid, with a very abundant whitish 
 precipitate (albuminose). There is also a peculiar odor developed 
 during this process, which resembles that produced in the malting 
 of barley. 
 
 Albuminose, in solution in gastric juice, has several peculiar 
 properties. One of the most remarkable of these is that it inter- 
 feres with the operation of Trommer's test for grape sugar (see 
 page 52). We first observed and described this peculiarity in 
 1854,' but could not determine, at that time, upon what particular 
 ingredient of the gastric juice it depended. A short time subse- 
 quently it was also noticed by M. Longet, in Paris, who published 
 his observations in the Gazette Sebdomadaire for February 9th, 
 1855.^ He attributed the reaction not to the gastric juice itself, 
 but to the albuminose held in solution by it. We have since found 
 this explanation to be correct. Gastric juice obtained from the 
 empty stomach of the fasting animal, by irritation with a metallic 
 catheter, which is clear and perfectly colorless, does not interfere 
 in any way with Trommer's test ; but if it be macerated for some 
 hours in a test-tube with finely chopped meat, at a temperature of 
 100°, it will then be found to have acquired the property in a 
 marked degree. The reaction therefore depends undoubtedly upon 
 the presence of albuminose in solution. As the gastric juice, drawn 
 from the dog's stomach half an hour or more after the introduction 
 of food, already contains some albuminose in solution, it presents 
 the same reaction. If such gastric juice be mixed with a small 
 quantity of glucose, and Trommer's test applied, no peculiarity is 
 observed on first dropping in the sulphate of copper ; but on adding 
 afterward the solution of potass, the mixture takes a rich purple hue, 
 instead of the clear blue tinge, which is presented under ordinary 
 circumstances. On boiling, the color changes to claret, cherry red, 
 and finally to a light yellow; but no oxide of copper is deposited, and 
 the fluid remains clear. If the albuminose be present only in small 
 
 ' American Journ. Med. Sci., Oct. 1854, p. 319. 
 
 * Nouvelles reclierches relatives a Taction du sue gastrique sur les substances 
 albuminoides. — Gaz. Hebd. 9 F^vrier, 1855, p. 103. 
 
112 DIGESTION. , 
 
 quantity, an incomplete reduction of the copper takes place, so that 
 the mixture becomes opaline and cloudy, but still without any well 
 marked deposit. This interference will take place when sugar is 
 present in very large proportion. We have found that in a mix- 
 ture of honey and gastric juice in equal volumes, no reduction of 
 copper takes place on the application of Trommer's test. It is 
 remarkable, however, that if such a mixture be previously diluted 
 with an equal quantity of water, the interference does not take 
 place, and the copper is deposited as usual. 
 
 Usually this peculiar reaction, now that we are acquainted with 
 its existence, will not practically prevent the detection of sugar, 
 when present ; since the presence of the sugar is distinctly indi- 
 cated by the change of color, as above mentioned, from purple to 
 yellow, though the copper may not be thrown down as a precipi- 
 tate. All possibility of error, furthermore, may be avoided by 
 adopting the following precautions. The purple color, already men- 
 tioned, will, in the first place, serve to indicate the presence of the 
 albuminoid ingredient in the suspected fluid. The mixture should 
 then be evaporated to dryness, and extracted with alcohol, in order 
 to eliminate the animal matters. After that, a watery solution of 
 the sugar contained in the alcoholic extract will react as usual with 
 Trommer's test, and reduce the oxide of copper without difficulty. 
 
 Another remarkable property of gastric juice containing albu- 
 minose, which is not, however, peculiar to it, but common to many 
 other animal fluids, is that of interfering with the m.utual reaction 
 of starch and iodine. If 5j of such gastric juice be mixed with 3j 
 of iodine water and boiled starch be subsequently added, no blue 
 color is produced; though if a larger quantity of iodine water be 
 added, or if the tincture be used instead of the aqueous solution, 
 the superabundant iodine then combines with the starch, and pro- 
 duces the ordinary blue color. This property, like that described 
 above, is not possessed by pure, colorless, gastric juice, taken from 
 the empty stomach, but is acquired by it on being digested with 
 albuminoid substances. 
 
 Another important action which takes place in the stomach, 
 beside the secretion of the gastric juice, is the peristaltic movement 
 of the organ. This movement is accomplished by the alternate 
 contraction and relaxation of the longitudinal and circular fibres 
 of its muscular coat. The motion is minutely described by Dr. 
 Beaumont, who examined it both by watching the movements of 
 the food through the gastric fistula, and also by introducing into 
 
THE GASTRIC JUICE, AND STOMACH DIGESTION. 113 
 
 the stomach the bulb and stem of a thermometer. According to 
 his observations, when the food first passes into the stomach, and 
 tlie secretion of the gastric juice commences, the muscular coat, 
 which was before quiescent, is excited and begins to contract ac- 
 tively. The contraction takes place in such a manner that the 
 food, after entering the cardiac orifice of the stomach, is first car- 
 ried to the left, into the great pouch of the organ, thence downward 
 and along the great curvature to the pyloric portion. At a short 
 distance from the p^dorus. Dr. B. often found a circular constric- 
 tion of the parietes, by which the bulb of the thermometer was 
 gently grasped and drawn toward the pylorus, at the same time 
 giving a twisting motion to the stem of the instrument, by which 
 it was rotated in his fingers. In a moment or two, however, this 
 constriction was relaxed, and the bulb of the thermometer again 
 released, and carried together with the food along the small curva- 
 ture of the organ to its cardiac extremity. This circuit was re- 
 peated so long as anyibod remained in the stomach; but as the 
 liquefied portions were successively removed toward the end of 
 digestion it became less active, and at last ceased altogether when 
 the stomach had become completely empty, and the organ returned 
 to its ordinary quiescent condition. 
 
 It is easy to observe the muscular action of the stomach during 
 digestion in the dog, by the assistance of a gastric fistula, artificially 
 established. If a metallic catheter be introduced through the 
 fistula when the stomach is empty, it must usually be held care- 
 fully in place, or it will fall out by its own weight. But immedi- 
 ately upon the introduction of food, it can be felt that the catheter 
 is grasped and retained with some force, by the contraction of the 
 muscular coat. A twisting or rotatory motion of its extremity 
 may also be frequently observed, similar to that described by Dr. 
 Beaumont. This peristaltic action of the stomach, however, is a 
 gentle one, and not at all active or violent in character. We have 
 never seen, in opening the abdomen, any such energetic or exten- 
 sive contractions of the stomach, even when full of food, as may 
 be easily excited in the small intestine by the mere contact of the 
 atmosphere, or by pinching them with the blades of a forceps. 
 This action of the stomach, nevertheless, though quite gentle, is 
 sufficient to produce a constant churning movement of the masti- 
 cated food, by which it is carried back and forward to every part 
 of the stomach, and rapidly incorporated with the gastric juice 
 which is at the same time poured out by the mucus membrane ; so 
 8 
 
114 DIGESTION. 
 
 that the digestive fluid is made to penetrate equally every part of 
 the alimentary mass, and the digestion of all its albuminous ingre- 
 dients goes on simultaneously. This gentle and continuous move- 
 ment of the stomach is one which cannot be successfully imitated 
 in experiments on artificial digestion with gastric juice in test-tubes; 
 and consequently the process, under these circumstances, is never 
 so rapid or so complete as when it takes place in the interior of the 
 stomach. 
 
 The length of time which is required for digestion varies in 
 different species of animals. In the carnivora a moderate meal of 
 fresh uncooked meat requires from nine to twelve hours for its 
 complete solution and disappearance from the stomach. According 
 to Dr. Beaumont, the average time required for digestion in the 
 human subject is considerably less; varying from one hour to five 
 hours and a half, according to the kind of food employed. This 
 is probably owing to the more complete mastication of the food 
 which takes place in man, than in the carnivorous animals. By 
 examining the contents of the stomach at various intervals after 
 feeding. Dr. Beaumont made out a list, showing the comparative 
 digestibility of different articles of food, of which the following are 
 the most important: — 
 
 Time required for digestion, according to Dr. Beaumont: — 
 
 Kind of Food. Hours. Minutes. 
 
 Pig's feet 1 00 
 
 Tripe 1 00 
 
 Trout (broiled) 1 30 
 
 Venison steak ........ 1 35 
 
 Milk 2 00 
 
 Roasted turkey 2 ^ 30 
 
 " beef 3 00 
 
 " mutton ........ 3 15 
 
 Veal (broiled) 4 00 
 
 Salt beef (boiled) .4 15 
 
 Roasted pork 5 15 
 
 The comparative digestibility of different substances varies more 
 or less in different individuals according to temperament ; but the 
 above list undoubtedly gives a correct average estimate of the time 
 required for stomach digestion under ordinary conditions. 
 
 A very interesting question is that which relates to the total 
 gwanfe'^y of gastric juice secreted daily. Whenever direct experi- 
 ments have been performed with a view of ascertaining this point, 
 their results have given a considerably larger quantity than was 
 anticipated. Bidder and Schmidt found that, in a dog weighing 
 
THE GASTRIC JUICE, AND STOMACH DIGESTION. 115 
 
 34 pounds, tliey were able to obtain by separate experiments, con- 
 suming in all 12 hours, one pound and three-quarters of gastric 
 juice. The total quantity, therefore, for 24 hours, in the same 
 animal, would be 3| pounds; and,. by applying the same calcula- 
 tion to a man of medium size, the authors estimate the total daily 
 quantity in the human subject as but little less than 14 pounds 
 (av.). This estimate is probably not an exaggerated one. In order 
 to determine the question, however, if possible, in a different way, 
 we adopted the following plan of experiment with the gastric juice 
 of the dog. It was first ascertained, by direct experiment, that the 
 fresh lean meat of the bullock's heart loses, by complete desicca- 
 tion, 78 per cent, of its weight. 800 grains of such meat, cut into 
 small pieces, were then digested for ten hours, in |iss of gastric 
 juice at 100° F.; the mixture being thoroughly agitated as often 
 as every hour, in order to insure the digestion of as large a quan- 
 tity of meat as possible. The meat remaining undissolved was 
 then collected on a previously weighed filter, and evaporated to 
 dryness. The dry residue weighed 55 grains. This represented, 
 allowing for the loss by evaporation, 250 grains of the meat, in its 
 natural moist condition ; 50 grains of meat were then dissolved by 
 siss of gastric juice, or 33 J grains per ounce. 
 
 From these data we can form some idea of the large quantity of 
 gastric juice secreted in the dog during the process of digestion. 
 One pound of meat is only a moderate meal for a medium-sized 
 animal ; and yet, to dissolve this quantity, no less than thirteen pints 
 of gastric juice will be necessary. This quantity, or any approxi- 
 mation to it, would be altogether incredible if we did not recollect 
 that the gastric juice, as soon as it has dissolved its quota of food, 
 is immediately reabsorbed, and again enters the circulation, together 
 with the alimentary substances jsvhich it holds in solution. The 
 secretion and reabsorption of the gastric juice then go on simulta- 
 neously ; and the fluids which the blood loses by one process are 
 incessantly restored to it by the other. A very large quantity, 
 therefore, of the secretion may be poured out during the digestion 
 of a meal, at an expense to the blood, at any one time, of only two 
 or three ounces of fluid. The simplest investigation shows that 
 the gastric juice does not accumulate in the stomach in any con- 
 siderable quantity during digestion ; but that it is gradually 
 secreted so long as any food remains undissolved, each portion, as 
 it is digested, being disposed of by reabsorption, together with its 
 solvent fluid. There is accordingly, during digestion, a constant 
 
116 DIGESTION. 
 
 circulation of the digestive fluids from the bloodvessels to the 
 alimentary canal, and from the alimentary canal back again to the 
 bloodvessels. 
 
 That this circulation really does take place is proved by the fol- 
 lowiog facts : First, if a dog be killed some hours after feeding, 
 there is never more than a very small quantity of fluid found in 
 the stomach, just sufficient to smear over and penetrate the half 
 digested pieces of meat ; and, secondly, in the living animal, gastric 
 juice, drawn from the fistula five or six hours after digestion has 
 been going on, contains little or no more organic matter in solution 
 than that extracted fifteen to thirty minutes after the introduction 
 of food. It has evidently been freshly secreted ; and, in order to 
 obtain gastric juice saturated with alimentary matter, it must be 
 artificially digested with food in test tubes, where this constant 
 absorption and renovation cannot take place. 
 
 An unnecessary difficulty has sometimes been felt in understand- 
 ing how it is that the gastric juice, which digests so readily all 
 albuminous substances, should not destroy the walls of tbe stomach 
 itself, which are composed of similar materials. This, in fact, was 
 brought forward at an early day, as an insuperable objection to the 
 doctrine of Reaumur and Spallanzani, that digestion was a process 
 of chemical solution performed by a digestive fluid. It was said 
 to be impossible that a fluid capable of dissolving animal matters 
 should be secreted by the walls of the stomach without attacking 
 them also, and destroying the organ by which it was produced. 
 Since that time, various complicated hypotheses have been framed, 
 in order to reconcile these apparently contradictory facts. The true 
 explanation, however, as we believe, lies in this — that the process 
 of digestion is not a simple solution, but a catalytic transformation 
 of the alimentary 'substances, produced by contact with the pep- 
 sine of the gastric juice. We know that all the organic sub- 
 stances in the living tissues are constantly undergoing, in the 
 process of nutrition, a series of catalytic changes, which are charac- 
 teristic of the vital operations, and which are determined by the 
 organized materials with which they are in contact, and by all the 
 other conditions present in the living organism. These changes, 
 therefore, of nutrition, secretion, &c., necessarily exclude for the 
 time all other catalyses, and take precedence of them. In the same 
 way, any dead organic matter, exposed to warmth, air, and moist- 
 ure, putrefies; but if immersed in gastric juice, at the same 
 temperature, the putrefactive changes are stopped or altogether 
 
THE GASTRIC JUICE, AND STOMACH DIGESTION. 117 
 
 prevented, because the catalytic actions, excited by the gastric 
 juice, take precedence of those which constitute putrefaction. For 
 a similar reason, the organic ingredient of the gastric juice, which 
 acts readily on dead animal matter, has no effect on the living 
 tissues of the stomach, because they are already subject to other 
 catalytic influences, which exclude those of digestion, as well as 
 those of putrefaction. As soon as life departs, however, and the 
 peculiar actions taking place in the living tissues come to an end 
 with the stoppage of the circulation, the walls of the stomach are 
 really attacked by the gastric juice remaining in its cavity, and 
 are more or less completely digested and liquefied. In the human 
 subject, it is rare to make an examination of the body twenty-four 
 or thirty-six hours after death, without finding the mucous mem- 
 brane of the great pouch of the stomach more or less softened and 
 disintegrated from this cause. Sometimes the mucous membrane 
 is altogether destroyed, and the submucous cellular layer exposed ; 
 and occasionally, when death has taken place suddenly during 
 active digestion, while the stomach contained an abundance of 
 gastric juice, all the coats of the organ have been found destroyed, 
 and a perforation produced leading into the peritoneal cavity. 
 These post-mortem changes show that, after death, the gastric 
 juice really dissolves the coats of the stomach without difficulty. 
 But during life, the chemical changes of nutrition, which are going 
 on in their tissues, protect them from its influence, and effectually 
 preserve their integrity. 
 
 The secretion of the gastric juice is much influenced by nervous 
 conditions. It was noticed by Dr. Beaumont, in his experiments 
 upon St. Martin, that irritation of the temper, and other moral 
 causes, would frequently diminish or altogether suspend the supply 
 of the gastric fluids. Any febrile action in the system, or any 
 unusual fatigue, was liable to exert a similar effect. Every one is 
 aware how readily any mental disturbance, such as anxiety, anger, 
 or vexation, will take away the appetite and interfere with diges- 
 tion. Any nervous impression of this kind, occurring at the com- 
 ■mencement of digestion, seems moreover to produce some change 
 which has a lasting effect upon the process ; for it is very often 
 noticed that when any annoyance, hurry, or anxiety occurs soon 
 after the food has been taken, though it may last only for a few 
 moments, the digestive process is not only liable to be suspended 
 for the time, but to be permanently disturbed during the entire, 
 day. In order that digestion, therefore, may go on properly in the 
 
118 . DIGESTION. 
 
 « 
 
 stomacli, food must be taken only when the appetite demands it ; 
 it should also be thoroughly masticated at the outset ; and, finally, 
 both mind and body, particularly during the commencement of the 
 process, should be free from any unusual or disagreeable excite- 
 ment. 
 
 INTESTINAL JUICES, AND THE DIGESTION OF SUGAR AND STARCH. 
 
 From the stomach, those portions of the food which have not 
 already suffered digestion, pass into the third division of the ali- 
 mentary canal, viz., the small intestine. As already mentioned, it 
 is only the albuminous matters which are digested jn the stomach. 
 Cane sugar, it is true, is slowly converted by the gastric juice, out- 
 side the body, into glucose. We have found that ten grains of 
 cane sugar, dissolved in §ss of gastric juice, give traces of glucose 
 at the end of two hours; and in three hours, the quantity of this 
 substance is considerable. It cannot be shown, however, that the 
 gastric juice exerts this effect on sugar during ordinary digestion. 
 If pure cane sugar be given to a dog with a gastric fistula, while 
 digestion of meat is going on, it disappears in from two to three 
 hours, without any glucose being detected in the fluids withdrawn 
 from the stomach. It is, therefore, either directly absorbed under 
 the form of cane sugar, or passes, little by little, into the duodenum, 
 where the intestinal fluids at once convert it into glucose. 
 
 "It is equally certain that starchy .matters are not digested in the 
 stomach, but pass unchanged into the small intestine. Here they 
 meet with the mixed intestinal fluids, which act at once upon the 
 starch, and convert it rapidly into sugar. The intestinal fluids, 
 taken from the duodenum of a recently killed dog, exert this 
 transforming action upon starch with the greatest promptitude, if 
 mixed with it in a test-tube and kept at the temperature of 100° F. 
 Starch is converted into sugar by this, means much more rapidly 
 and certainly than by the saliva; and experiment shows that the 
 intestinal fluids are the active agents in its digestion during life. 
 If a dog be fed with a mixture of meat and boiled starch, and killed 
 a short time after the meal, the stomach is found to contain starch 
 but no sugar; while in the small intestine there is an abundance of 
 sugar, and but little or no starch. If some observers have failed 
 to detect sugar in the intestine after feeding the animal with 
 starch, it is because they have delayed the examination until too 
 
INTESTINAL JUICES, DIGESTION OF SUGAR, ETC. 119 
 
 late. For it is remarkable how rapidly starchy substances, if 
 previously disintegrated by boiling, are disposed of in the digest- 
 ive process. If a dog, for example, be fed as above with boiled 
 starch and meat, while some of the meat remains in the stomach 
 for eight, nine, or ten hours, the starch begins immediately to 
 pass into the intestine, where it is at once converted into sugar, 
 and then as rapidly absorbed. The whole of the starch may 
 be converted into sugar, and completely absorbed, in an hour's 
 time. We have even found, at the end of three-quarters of an 
 hour, after a tolerably full meal of boiled starch and meat, that all 
 trace of both starch and sugar had disappeared from both stomach 
 and intestine. The rapidity with which this passage of the starch 
 into the duodenum takes place varies, to some extent, in different 
 animals, according to the general activity of the digestive appa- 
 ratus; but it is always a comparatively rapid process, when the 
 starch is already liquefied and is administered in a pure form. 
 There can be no doubt that the natural place for the digestion of 
 starchy matters is the small intestine, and that it is accomplished 
 by 'the action of the intestinal juices. 
 
 Our knowledge is not very complete with regard to the exact 
 nature of the fluids by which this digestion of the starch is accom- 
 plished. The juices taken from the duodenum are generally a 
 mixture of three different secretions, viz., the bile, the pancreatic 
 fluid, and the intestinal juice proper. Of these, the bile may be 
 left out of the question; since it does not, when in a pure state, 
 exert any digestive action on starch. The pancreatic juice, on the 
 other hand, has the property p. gi 
 
 of converting starch into su- 
 gar; but it is not known 
 whether this fluid be always 
 present in the duodenum. 
 The true intestinal juice is the 
 product of two sets of glan- 
 dular organs, seated in the 
 substance of or beneath the 
 mucous membrane, viz., the 
 follicles of LieberkiJhn and 
 the glands of Brunner. The 
 first of these, or Lieberkiihn's 
 follicles (Fig. 31), are the most 
 numerous. They are simple, follicles op lieberkuhx, from smaii in- 
 
 '' ^ testine of Pig. 
 
120 
 
 DIGESTION. 
 
 Dearly straight tubules, lined witli columnar epithelium, and some- 
 what similar in their appearance to the follicles of the pyloric 
 portion of the stomach. They occupy the whole thickness of the 
 mucous membrane, and are found in great numbers throughout the 
 entire length of the small and large intestine. 
 
 The glands of Brunner (Fig. 32), or the duodenal glandulse, as 
 
 they are sometimes called, are 
 Fig. 32. ^ confined to the upper part of 
 
 the duodenum, where they 
 exist, as a closely set layer, 
 in the deeper portion of the 
 mucous membrane, extending 
 downward a short distance 
 from the pylorus. They are 
 composed of a great number 
 of rounded follicles, or culs-de- 
 sac, clustered round a central 
 excretory duct. Each follicle 
 consists of a delicate mem- 
 branous wall, lined with glan- 
 dular epithelium, and covered 
 on its surface with small, dis- 
 tinctly marked nuclei. The 
 follicles collected round each duct are bound together by a thin 
 layer of areolar tissue, and covered with a plexus of capillary 
 bloodvessels. 
 
 The intestinal jaice, which is the secreted product of the above 
 glandular organs, has been less successfully studied than the other 
 digestive fluids, owing to the difficulty of obtaining it in a pure 
 state. The method usually adopted has been to make an opening 
 in the abdomen of the living animal, take out a loop of intestine, 
 empty it by gentle pressure, and then to shut off a portion of it 
 from the rest of the intestinal cavity by a couple of ligatures, 
 situated six or eight inches apart; after which the loop is returned 
 into the abdomen, and the external wound closed by sutures. 
 After sis or eight hours the animal is killed, and the fluid, which 
 has collected in the isolated portion of intestine, taken out and 
 examined. The above was the method adopted by Frerichs. Bid- 
 der and Schmidt, in order to obtain pure intestinal juice, first tied 
 the biliary and pancreatic ducts, so that both the bile and the pan- 
 creatic juice should be shut out from the intestine, and then estab- 
 
 Portion of one of Brtsner's Duodexal 
 Glands, from Human Intestine. 
 
PANCREATIC JUICE, AND THE DIGESTION OF FAT. 121 
 
 lished an intestinal fistula below, from which they extracted the 
 fluids which accumulated in the cavity of the gut. From the great 
 abundance of the follicles of Lieberkiihn, we should expect to find 
 the intestinal juice secreted in large quantity. It appears, however, 
 in point of fact, to be quite scanty, as the quantity collected in the 
 above manner by experimenters has rarely been sufficient for a 
 thorough examination of its properties. It seems to resemble very 
 closely, in its physical characters, the secretion of the mucous fol- 
 licles of the mouth. It is colorless and glassy in appearance, viscid 
 and mucous in consistency, and has a distinct alkaline reaction. 
 It has the property, when pure, as well as when mixed with other 
 secretions, of rapidly converting starch into sugar, at the tempe- 
 rature of the living body. 
 
 PANCREATIC JUICE, AND THE DIGESTION OF FAT, 
 
 The only remaining ingredients of the food that require digestion 
 are the oily matters. These are not affected, as we have already 
 stated, by contact with the gastric juice ; and examination shows, 
 furthermore, that they are not digested in the stomach. So long 
 as they remain in the cavity of this organ they are unchanged in 
 their essential properties. They are merely melted by the warmth 
 of the stomach, and set free by the solution of the vesicles, fibres, 
 or capillary tubes in which they are contained, or among which 
 they are entangled ; and are still readily discernible by the eye, 
 floating in larger or smaller drops on the surface of the semi-fluid 
 alimentary mass. Yery soon, however, after its entrance into the 
 intestine, the oily portion of the food loses its characteristic ap- 
 pearance, and is converted into a white, opaque emulsion, which is 
 gradually absorbed. This emulsion is termed the chyle^ and is 
 always found in the small intestine during the digestion of fat, 
 entangled among the valvulse conniventes, and adhering to the 
 surface of the villi. The digestion of the oil, however, and its con- 
 version into chyle, does not take place at once upon its entrance 
 into the duodenum, but only after it has passed the orifices of the 
 pancreatic and biliary ducts. Since these ducts almost invariably 
 open into the intestine at or near the same point, it was for a long 
 time dif&cult to decide by which of the two secretions the digestion 
 of the oil was accomplished. M. Bernard, however, first threw 
 some light on this question by experimenting on some of the lower 
 
122 DIGESTION. 
 
 animals, in whidi the two ducts open separately. In the rabbit, 
 for example, the biliary duct opens as usual just below the pylorus, 
 while the pancreatic duct communicates with the intestine some 
 eight or ten inches lower down. Bernard fed these animals "with 
 substances containing oil, or injected melted butter into the stomach; 
 and, on killing them afterward, found that there was no chyle in 
 the intestine between the opening of the biliary and pancreatic 
 ducts, but that it was abundant immediately below the orifice of 
 the latter. Above this point, also, he fo'und the lacteals empty or 
 transparent, while below it they were full of white and opaque 
 chyle. The result of these experiments, which have since been 
 confirmed by Prof. Samuel Jackson of Philadelphia,' lead to the 
 conclusion that the pancreatic fluid is the active agent in the diges- 
 tion of oily substances; and an examination of the properties of 
 this secretion, when obtained in a pure state from the living animal, 
 fully confirm the above opinion. 
 
 In order to obtain pancreatic juice from the dog, the animal 
 must be etherized soon after digestion has commenced, an incision 
 made in the upper part of the abdomen, a little to the right of the 
 median line, and a loop of the duodenum, together with the lower 
 extremity of the pancreas which lies adjacent to it, drawn out at 
 the external wound. The pancreatic duct is then to be exposed 
 and opened, and a small silver canula inserted into it and secured 
 by a ligature. The whole is then returned into the abdomen and 
 the wound closed by sutures, leaving only the end of the canula 
 projecting from it. In the dog there are two pancreatic ducts, 
 situated from half an inch to an inch apart. The lower one of 
 these, which is usually the larger of the two, is the one best adapted 
 for the insertion of the canula. After the eSects of etherization 
 have passed off, and the digestive process has recommenced, the 
 pancreatic juice begins to run from the orifice of the canula, at first 
 very slowly and in drops. Sometimes the drops follow each other 
 with rapidity for a few moments, and then an interval occurs during 
 which the secretion seems entirely suspended. After a time it 
 recommences, and continues to exhibit similar fluctuations during 
 the whole course of the experiment. Its flow, however, is at all 
 times scanty, compared with that of the gastric juice ; and we have 
 never been able to collect at most more than five or six drachms 
 during a period of several hours. Bidder and Schmidt obtained 
 
 ' American Journ. Med. Sci., Oct. 1854. 
 
PANCREATIC JUICE, AND THE DIGESTION OF FAT. 123 
 
 on an average, from a dog weighing 44 pounds, 14|- grains of pan- 
 creatic juice per hour ; and they calculate from this that the average 
 daily quantity in the human subject is rather less than 2500 grains, 
 or a little over one-third of a pound avoirdupois. 
 
 Pancreatic juice obtained by the above process is a clear, color- 
 less, somewhat viscid fluid, with a distinct alkaline reaction. Its 
 composition, according to the analysis of Bidder and Schmidt, is 
 as follows : — 
 
 Composition of Pancreatic Juice. 
 
 Water 900.76 
 
 Organic matter (pancreatine) ....... 90.38 
 
 Chloride of sodium ......... 7.36 
 
 Free soda .......... 0.32 
 
 Phosphate of soda 0.45 
 
 Sulphate of soda . 0.10 . 
 
 Sulphate of potass ■ . . 0.02 
 
 r Lime 0.54 
 
 Combinations of } Magnesia ....... 0.05 
 
 y Oxide of iron 0.02 
 
 1000.00 
 
 The most important ingredient of the pancreatic juice is its 
 organic matter or pancreatine. It will be seen that this is much 
 more abundant in proportion to the other ingredients of the secre- 
 tion than the organic matter of any other digestive fluid. It is 
 coagulable by heat; and the pancreatic juice often solidifies com- 
 pletely on boiling, like white of egg, so that not a drop of fluid 
 remains after its coagulation. It is precipitated, furthermore, by 
 nitric acid and by alcohol, and also by sulphate of magnesia in 
 excess. By this last property, it may be distinguished from albu- 
 men, which is not affected by contact with sulphate of magnesia. 
 
 Fresh pancreatic juice, brought into contact with oily matters at 
 the temperature of the body, exerts upon them, as was first noticed 
 by Bernard, a very peculiar effect. It disintegrates them, and re- 
 duces them to a state of complete emulsion, so that the mixture is 
 at once converted into a white, opaque, creamy-looking fluid. This 
 effect is instantaneous and permanent, and only requires that the 
 two substances be well mixed by gentle agitation. It is singular 
 that some of the German observers should deny that the pancreatic 
 juice possesses this property, of emulsioning fat, to a greater extent 
 than the bile and some other digestive fluids; and should state that 
 although, when shaken up with oil, outside the body, it reduces 
 the oily particles to a state of extreme minuteness, the emulsion 
 
124 DIGESTION. 
 
 is not permanent, and the oily particles "soon separate again on 
 the surface.'" We have frequently repeated this experiment with 
 different specimens of pancreatic juice obtained from the dog, and 
 have never failed to see that the emulsion produced by it is by 
 far more prompt and complete than that which takes place with 
 saliva, gastric juice, or bile. The effect produced by these fluids is 
 in fact altogether insignificant, in comparison with the prompt and 
 energetic action exerted by the pancreatic juice. The emulsion 
 produced with the latter secretion may be kept, furthermore, for at 
 least twenty-four hours, according to our observations, without any 
 appreciable separation of the oily particles, or a return to their 
 original condition. 
 
 The pancreatic juice, therefore, is peculiar in its action on oily 
 substances, and reduces them at once to the condition of an emul- 
 sion. The oil, in this process, does not suffer any chemical altera- 
 tion. It is not decomposed or saponified, to any appreciable extent. 
 It is simply emulsioned; that is, it is broken up into a state of minute 
 subdivision, and retained in suspension by contact with the organic 
 matter of the pancreatic juice. That its chemical condition is not 
 altered is shown by the fact that it is still soluble in ether, which 
 will withdraw the greater part of the fat from a mixture of oil and 
 pancreatic juice, as well as from the chyle in the interior of the 
 intestine. In a state of emulsion the fat, furthermore, is capable 
 of being absorbed, and its digestion may be then said to be accom- 
 plished. 
 
 We find, then, that the digestion of the food is not a simple 
 operation, but is made up of several different processes, which 
 commence successively in different portions of the alimentary 
 canal. In the first place, the food is subjected in the mouth to the 
 physical operations of mastication and insalivation. Eeduced to a 
 soft pulp and mixed abundantly with the saliva, it passes, secondly, 
 into the stomach. Here it excites the secretion of the gastric juice, 
 by the influence of which its chemical transformation and solution 
 are commenced. If the meal consist wholly or partially of mus- 
 cular flesh, the first effect of the gastric juice is to dissolve the 
 intervening cellular substance, by which the tissue is disintegrated 
 and the muscular fibres separated from each other. Afterward 
 the muscular fibres themselves become swollen and softened by 
 the imbibition of the gastric fluid, and are finally disintegrated 
 and liquefied. In the small intestine, the pancreatic and intestinal 
 
 ' Lehmann's Physiological Chemistry. Philada. ed., vol. i. p. 507. 
 
PHENOMENA OF INTESTINAL DIGESTION. 125 
 
 juices convert the starchy ingredients of the food into sugar, and 
 break up the fatty matters into a fine emulsion, by which they 
 are converted into chyle. 
 
 Although the separate actions of these digestive fluids, however, 
 commence at different points of the alimentary canal, they after- 
 ward go on simultaneously in the small intestine ; and the changes 
 Avhich take place here, and which constitute the process of intestinal 
 digestion, form at the same time one of the most complicated and 
 one of the most important parts of the whole digestive function. 
 
 The phenomena of intestinal digestion may be studied, in the 
 dog, by killing the animal at various periods after feeding, and 
 examining the contents of the intestine. We have also succeeded, 
 by establishing, in the same animal, an artificial intestinal fistula, 
 in gaining still more satisfactory information on this point. The 
 fistula may be established, for this purpose, by an operation precisely 
 similar to that already described as employed for the production of 
 a permanent fistula in the stomach. The silver tube having been 
 introduced into the lower part of the duodenum, the wound is 
 allowed to heal, and the intestinal secretions may then be with- 
 drawn at will, and subjected to examination at different periods 
 during digestion. 
 
 By examining in this way, from time to time, the intestinal 
 fluids, it at once becomes ^manifest that the action of the gastric 
 juice, in the digestion of albuminoid substances, is not confined to 
 the stomach, but continues after the food has passed into the intes- 
 tine. About half an hour after the injection of a meal, the gastric 
 juice begins to pass into the duodenum, where it may be recognized 
 by its strongly-marked acidity, and by its peculiar action, already 
 described, in interfering with Trommer's test for grape sugar. It 
 has accordingly already dissolved some of the ingredients of the 
 food while still in the stomach, and contains a certain quantity of 
 albuminose in solution. It soon afterward, as it continues to pass 
 into the duodenum, becomes mingled with the debris of muscular 
 fibres, fat vesicles, and oil drops; substances which are easily 
 recognizable under the microscope, and which produce a grayish 
 turbidity in the fluid drawn from the fistula. This turbid admix- 
 ture becomes thicker and thicker from the second to the tenth or 
 twelfth hour; after which the intestinal fluids become rapidly less 
 abundant, and finally disappear almost entirely, as the process of 
 digestion comes to an end. 
 
 The passage of disintegrated muscular tissue into the intestine 
 
126 
 
 DIGESTION. 
 
 CosTENTS OP Stomach dueixg Digestion 
 OF Meat, from the Dog. — a. Fat Vesicle, filled with 
 opaque, solid, granular fat. b, h. Bits of partially dis- 
 integrated muscular fibre, c. Oil globules. 
 
 may also be shown, as already mentioned, by killing the animal 
 and examining the contents of the alimentary canal. During the 
 
 digestion of muscular flesh 
 ^^s- 33. 2,xi(\ adipose tissue, the sto- 
 
 mach contains masses of soft- 
 ened meat, smeared over with 
 gastric juice, and also a mo- 
 derate quantity of grayish 
 grumous fluid, with an acid 
 reaction. This fluid contains 
 muscular fibres, isolated from 
 each other, and more or less 
 disintegrated by the action 
 of the gastric juice. (Fig. 33.) 
 The fat vesicles are but little 
 or not at all altered in the 
 stomach, and there are only 
 a few free oil globules to be 
 seen floating in the mixed 
 fluids, contained in the cavity 
 of the organ. In the duodenum the muscular fibres are further 
 disintegrated. (Fig. 3J:.) They become very much broken up, pale 
 
 and transparent, but can still 
 ^^^' be recognized by the granu- 
 
 lar markings and striations 
 which are characteristic of 
 them. The fat vesicles also 
 begin to become altered in 
 the duodenum.. The solid 
 granular fat of beef, and simi- 
 lar kinds of meat, becomes 
 liquefied and emulsioned; and 
 appears under the form of 
 free oil drops and fatty mole- 
 cules; while the fat vesicle 
 itself is partially emptied, and 
 
 From Dtodexum of Dog, ditrixg Diges- bcCOmeS morC Or IcSS Col- 
 
 TiON OF Meat. — a. Fat vesicle, with its. contents , j i i • n l T„ j-U^ 
 
 diminishing. The vesicle is beginning to shrivel and lapSCd and shriVClled. In the 
 
 the fat breaking up. 6, 6. Disintegrated muscular middle and loWCr partS of the 
 
 fibre, e, c. Oil globules. . . ,.p,. n~ j o/j\ 
 
 intestine (Figs. 3o and 36) 
 these changes continue. The muscular fibres become constantly 
 
PHENOMENA OF INTESTINAL DIGESTION. 
 
 127 
 
 Fig. 35. 
 
 more and more disintegrated, and a large quantity of granular 
 debris is produced, wliich is at last also dissolved. The fat also 
 progressively disappears, and 
 the vesicles may be seen in 
 the lower part of the intes- 
 tine, entirely collapsed and 
 empty. 
 
 In this way the digestion 
 of tlie different ingredients of 
 the food goes on in a con- 
 tinuous manner, from the sto- 
 mach throughout the entire 
 length of the small intestine. 
 At the same time, it results 
 in the production of three 
 diflerent substances, viz : 1st. 
 Albuminose, produced by the ^ ,, o . 
 
 ' '■ ... From Middle of Small Intestine. — a, a. 
 
 action of the gastric juice Fat vesicles, nearly emptied of their contents. 
 
 on the albuminoid matters; 
 
 2d. An oily emulsion, pro- 
 duced by the action of the 
 pancreatic juice on fat; and, 
 3d. Sugar, produced from the 
 transformation of starch by 
 the mixed intestinal fluids. 
 These substances are then 
 ready to be taken up into 
 the circulation ; and the next 
 change which they undergo, 
 in the regular course of the 
 vital processes, is that of ah- 
 sorption. This process will 
 form the subject of the next 
 chapter. 
 
 Fig. 36. 
 
 From last quarter of Small Intestine. 
 -a, a. Fat vesicles, quite empty and shrivelled. 
 
128 
 
 ABSORPTION". 
 
 CHAPTEK VII. 
 
 ABSORPTION. 
 
 Beside the glands of Brunner and the follicles of Lieberkiihii, 
 already described, there are, in the inner part of the walls of the 
 
 intestine, certain glandular- 
 
 Fig. 37. 
 
 One of the closed Follicles of Peter's 
 Patches, from Small Intestine of Pig. Magnified 
 50 diameters. 
 
 Fig. 38. 
 
 Glanduls; Agminat;e, from Small Intestine 
 of Pig. Magnified 20 diameters. 
 
 looking bodies which are 
 termed " glandulse solitariae," 
 and " glandulae agminatse." 
 The glandulse solitariae are 
 globular or ovoid bodies, 
 about one-thirtieth of an inch 
 in diameter, situated partly 
 in, and partly beneath, the 
 intestinal mucous membrane. 
 Each glandule (Fig. 37) is 
 formed of an investing cap- 
 sule, closed on all sides, and 
 containing in its interior a 
 soft pulpy mass, which con- 
 sists of minute cellular bodies, 
 imbedded in a homogeneous 
 substance. The inclosed mass 
 is penetrated by capillary 
 bloodvessels, which penetrate 
 through the investing cap- 
 sule, inosculate freely with 
 each other, and return upon 
 themselves in loops, near the 
 centre of the glandular body. 
 There is no external opening 
 or duct ; in fact, the contents 
 of the vesicle, being pulpy 
 and vascular, as already de- 
 scribed, are not to be regarded 
 
ABSORPTION. 
 
 129 
 
 as a secretion, but as constituting a kind of solid glandular tissue. 
 The gland ul^e agminate (Fig. 38), or " Payer's patches," as they are 
 sometimes called, consist of aggregations of similar globular or 
 ovoid bodies, found most abundantly toward the lower extremity of 
 the small intestine. Both the solitary and agminated glandules are 
 evidently connected with the lacteals and the system of the mesen- 
 teric glands, which latter organs they resemble very much in their 
 minute structure. They are probably to be regarded as the first 
 row of mesenteric glands, situated in the walls of the intestinal 
 canal. 
 
 Another set of organs, intimately connected with the process of 
 absorption, are the villi of the small intestine. These are conical 
 vascular eminences of the mucous membrane, thickly set over the 
 whole internal surface of the small intestine. In the upper portion of 
 the intestine, they are flattened and triangular in form, resembling 
 somewhat the conical projections of the pyloric portion of the sto- 
 mach. In the lower part, they are long and filiform, and often 
 slightly enlarged, or club-shaped, at their free extremity (Fig. 89), 
 and frequently attaining the length of 
 one-thirty-fifth of an inch. They are 
 covered externally with a layer of 
 columnar epithelium, similar to that 
 which lines the rest of the intestinal 
 mucous membrane, and contain in their 
 interior two sets of vessels. The most 
 superficial of these are the capillary 
 bloodvessels, which are supplied in each 
 villus by a twig of the mesenteric 
 artery, and which form, by their fre- 
 quent inosculation, an exceedingly close 
 and abundant network, almost imme- 
 diately beneath the epithelial layer. 
 The}^ unite at the base of the villus, 
 and form a minute vein, which is one 
 of the commencing rootlets of the por- 
 tal vein. In the central part of the vil- 
 lus, and lying nearly in its axis, there 
 is another vessel, with thinner and more 
 transparent walls, which is the commencement of a lacteal. The 
 precise manner in which the lacteal originates in the extremity of 
 the villus is not known. It commences near the apex, either by a 
 9 
 
 Extremity of I x testis a i. 
 Villus; from the Dog. — u. Layer of 
 epithelium, b. Bloodvessel, c. Lacteal 
 
 vessel. 
 
130 ABSORPTION. 
 
 blind extremity or by an irregular plexus, passes, in a straight or 
 somewhat wavy line, toward the base of the villus, and then becomes 
 continuous with a small twig of the mesenteric lacteals. 
 
 The villi are the active agents in the process of absorption. By 
 their projecting form, and their great abundance, they increase enor- 
 mously the extent of surface over which the digested fluids come 
 in contact with the intestinal mucous membrane, and increase, also, 
 to a corresponding degree, the energy with which absorption takes 
 place. They hang out into the nutritious, semi-fluid mass contained 
 in the intestinal cavity, as the roots of a tree penetrate the soil; and 
 they imbibe the liquefied portions of the food, with a rapidity which 
 is in direct proportion to their extent of surface, and the activity of 
 their circulation. 
 
 The process of absorption is also hastened by the peristaltic 
 movements of the intestine. The muscular layer here, as in other 
 parts of the alimentary canal, is double, consisting of both circular 
 and longitudinal fibres. The action of these fibres may be readily 
 seen by pinching the exposed intestine with the blades of a forceps. 
 A contraction then takes place at the spot irritated, by which the 
 intestine is reduced in diameter, its cavity obliterated, and its con- 
 tents forced onward into the succeeding portion of the alimentary 
 canal. The local contraction then propagates itself to the neighbor- 
 ing parts, while the portion originally contracted becomes relaxed ; 
 so that a slow, continuous, creeping motion of the intestine is pro- 
 duced, by successive waves of contraction and relaxation, which 
 follow each other from above downward. At the same time, the 
 longitudinal fibres have a similar alternating action, drawing the 
 narrowed portions of intestine up and down, as they successively 
 enter into contraction, or become relaxed in the intervals. The effect 
 of the whole is to produce a peculiar, writhing, worm-like, or 
 "vermicular" motion, among the different coils of intestine. During 
 life, the vermicular or peristaltic motion of the intestine is excited 
 by the presence of food undergoing digestion. By its action, the 
 substances which pass from the stomach into the intestine are 
 steadily carried from above downward, so as to traverse the entire 
 length of the small intestine, and to come in contact successively 
 with the whole extent of its mucous membrane. During this pas- 
 sage, the absorption of the digested food is constantly going on. 
 Its liquefied portions are taken up by the villi of the mucous mem- 
 brane, and successively disappear; so that, at the termination of the 
 small intestine, there remains only the undigestible portion of the 
 
ABSORPTION. 
 
 131 
 
 food, together, with the refuse of the intestinal secretions. These 
 pass through the ileo-ca?cal orifice into the large intestine, and there 
 become reduced to the condition of feces. 
 
 The absorption of the digested fluids is accomplished both by 
 the bloodvessels and the lacteals. It was formerly supposed that 
 the lacteals were the only agents in this process; but it has now 
 been long known that this opinion was erroneous, and that the 
 bloodvessels take at least an equal part in absorption, and are in 
 some respects the most active and important agents of the two. 
 Abundant experiments have demonstrated not only that soluble 
 substances introduced into the intestine may be soon afterward 
 detected in tlie blood of the portal vein, but that absorption takes 
 place more rapidly and abundantly by the bloodvessels than it does 
 by the lacteals. The most decisive of these experiments were 
 those performed by Panizza on the abdominal circulation.' This 
 observer opened the abdomen of a horse and drew out a fold of 
 the small intestine, eight or nine inches in length (Fig. 40, a, a), 
 
 ¥m. 40. 
 
 P A>-izz a"s ExPEK IME XT. — art. Intestine, b. Point of ligature of iiie.«Rnteric vein, n Opening 
 in intestine for introduction of poison, d. Opening in mesenteric vein behind the ligature. 
 
 which he included between two ligatures. A ligature was then 
 placed (at b) upon the mesenteric vein receiving the blood from 
 this portion of intestine; and, in order that the circulation might 
 not be interrupted, an opening was made (at d) in the vein behind 
 
 ' In Matteucci's Lectures on the Physical Phenomena of Living Beings, Pereira's 
 edition, p. 83. 
 
132 ABSORPTION. 
 
 the ligature, so that the blood brought by the mesenteric artery, 
 after circulating in the intestinal capillaries, passed out at the 
 opening, and was collected in a vessel for examination. Hydro- 
 cyanic acid was then introduced into the intestine by an opening at 
 c, and almost immediately afterward its presence was detected in 
 the venous blood flowing from the orifice at d. The animal, how- 
 ever, was not poisoned, since the acid was prevented from gaining 
 an entrance into the general circulation by the ligature at h. 
 
 Panizza afterward varied this experiment in the following 
 manner: Instead of tying the mesenteric vein, he simply com- 
 pressed it. Then, hydrocyanic acid being introduced into the 
 intestine as above, no effect was produced on the animal, so long 
 as compression was maintained upon the vein. But as soon as the 
 blood was allowed to pass again through the vessels, symptoms of 
 general poisoning at once became manifest. Lastly, in a third 
 experiment, the same observer removed all the nerves and lacteal 
 vessels supplying the intestinal fold, leaving the bloodvessels alone 
 untouched. Hydrocyanic acid now being introduced into the intes- 
 tine, found an entrance at once into the general circulation, and the 
 animal was immediately poisoned The bloodvessels, therefore, are 
 not only capable of absorbing fluids from the intestine, but may 
 even take them up more rapidly and abundantly than the lacteals. 
 These two sets of vessels, however, do not absorb all the alimen- 
 tary matters indiscriminately. It is one of the most important of 
 the facts which have been established by modern researches on 
 digestion that tbe different substances, produced by the operation of 
 the digestive fluids on the food, pass into the circulation by different 
 routes. The fatty matters are taken up by the lacteals under the form 
 of chyle, while the saccharine and albuminous matters pass by ab- 
 sorption into the portal vein. Accordingly, after the digestion of a 
 meal containing starchy and animal matters mixed, albuminose and 
 sugar are botb found in the blood of the portal vein, while they can- 
 not be detected, in any large quantity, in the contents of the lacteals. 
 These substances, bowever, do not mingle at once with the general 
 mass of the circulation, but owing to the anatomical distribution of 
 the portal vein, pass first through the capillary circulation of the 
 liver. Soon after being introduced into the blood, and coming in 
 contact with its organic ingredients, they become altered and con- 
 verted, by catalytic transformation, into other substances. The 
 albuminose passes into the condition of ordinary albumen, and 
 probably also partly into that of fibrin ; while the sugar rapidly 
 
ABSORPTION, 
 
 133 
 
 Fig. 41. 
 
 becomes decomposed, and loses its characteristic properties; so 
 that, on arriving at the entrance of the general circulation, both 
 these newly absorbed ingredients have become already assimilated 
 to those which previously existed in the blood. 
 
 The chyle in the intestine consists, as we have already mentioned, 
 of oily matters which have not been chemically altered, but simply 
 reduced to a state of emulsion. In chyle drawn from the lacteals 
 or the thoracic duct (Fig. 41), it still presents itself in the same 
 condition and retains all the 
 chemical properties of oil. 
 Examined by the microscope, 
 it is seen to exist under the 
 form of fine granules and 
 molecules, which present the 
 ordinary appearances of oil 
 in a state of minute subdivi- 
 sion. The chyle, therefore, 
 does not represent the entire 
 product of the digestive pro- 
 cess, but contains only the 
 fatty substances, suspended 
 by emulsion in a serous fluid. 
 
 During the time that intes- 
 tinal absorption is going on, 
 after a meal containing fatty 
 
 ingredients, the lacteals may be seen as white, opaque vessels, dis- 
 tended with milky chyle, passing through the mesentery, and con- 
 verging from its intestinal border toward the receptaculum chyli, 
 near the spinal column. During their course, they pass through 
 several successive rows of mesenteric glands, which also become 
 turgid with chyle, while the process of digestion is going on. The 
 lacteals then conduct the chyle to the receptaculum chyli, whence 
 it passes upward through the thoracic duct, and is finally dis- 
 charged, at the termination of this canal, into the left subclavian 
 vein. (Fig. 42.) It is then mingled with the returning current of 
 venous blood, and passes into the right cavities of the heart. 
 
 The lacteals, however, are not a special system of vessels by them- 
 selves, but are simply a part of the great system of " absorbent" or 
 " lymphatic" vessels, which are to be found everywhere in the integu- 
 ments of the head, the parietes of the trunk, the upper and lower 
 extremities, and in the muscular tissues and mucous membranes 
 
 Chyle from c o m m e x c e .m e x t o f Thoracic 
 PtJCT, from the Dog. — The molecules viiiy iu size 
 from 1-1 0,000th of au inch dowu-ward. 
 
134 
 
 ABSORPTION. 
 
 throughout the body. The walls of these vessels are thinner and 
 more transparent than those of the arteries and veins, and they 
 
 'are consequently less easily de- 
 tected by ordinary dissection. 
 They originate in the tissues of 
 the above-mentioned parts by 
 an irregular plexus. They 
 pass from the extremities to- 
 ward the trunk, converging and 
 uniting with each other like the 
 veins, their principal branches 
 taking usually the same direc- 
 tion with the nerves and blood- 
 vessels, and passing, at various 
 points in their course, through 
 certain glandular bodies, the 
 "lymphatic" or "absorbent" 
 glands. The lymphatic glands, 
 among which are included the 
 mesenteric glands, consist of an 
 external layer of fibrous tissue 
 and a contained pulp or paren- 
 chyma. The investing layer 
 of fibrous tissue sends off thin 
 septa or laminae from its inter- 
 nal surface, which penetrate 
 the substance of the gland in 
 every direction and unite with 
 each other at various points. 
 In this way they form an interlacing laminated framework, which 
 divides the substance of the gland into numerous roianded spaces 
 or alveoli. These alveoli are not completely isolated, but communi- 
 cate with each other by narrow openings, where the intervening 
 septa are incomplete. These cavities are filled with a soft, reddish 
 pulp, which is penetrated, according to Kolliker, like the solitary 
 and agminated glands of the intestine, by a fine network of capil- 
 lary bloodvessels. The solitary and agminated glands of the 
 intestine are, therefore, closely analogous in their structure to the 
 lymphatics. The former are to be regarded as simple, the latter as 
 compound vascular glands. 
 
 The arrangement of the lymphatic vessels in the interior of the 
 
 Lacteals, Thoracic Duct, &c. — a. Intes- 
 tine, h. Vena cava inferior, c, c. Kight and left 
 subclavian veins, d. Point of opening of thoracic 
 duct into left subclavian. 
 
ABSOEPTION. 135 
 
 glands is not precisely understood. Each lymphatic vessel, as it 
 enters the gland, breaks up into a number of minute ramifications, 
 the vasa afferentia ; and other similar twigs, forming the vasa effer- 
 entia^ pass off in the opposite direction, from the further side of the 
 gland ; but the exact mode of communication between the two has 
 not been definitely ascertained. All the fluids, however, arriving 
 by the vasa afferentia, must pass in some way through the tissue of 
 the gland, before they are carried away again by the vasa efferentia. 
 From the lower extremities the lymphatic vessels enter the abdomen 
 at the groin and converge toward the receptaculum chyli, into 
 which their fluid is discharged, and afterward conveyed, by the 
 thoracic duct, to the left subclavian vein. 
 
 The fluid which these vessels contain is called the lymph. It is 
 a colorless or slightly yellowish transparent fluid, which is absorbed 
 by the lymphatic vessels from the tissues in which they originate. 
 But little is known regarding its composition, except that it con- 
 tains, beside water and saline matters, a small quantity of fibrin 
 and albumen. Its ingredients are evidently derived from the meta- 
 morphosis of the tissues, and are returned to the centre of the 
 circulation in order to be eliminated by excretion, or in order to 
 undergo some new transforming or renovating process. We are 
 ignorant, however, with regard to the precise nature of their charac- 
 ter and destination. 
 
 The lacteals are simply that portion of the absorbents which 
 originate in the mucous membrane of the small intestine. During 
 the intervals of digestion, these vessels contain a colorless and 
 transparent lymph, entirely similar to that which is found in other 
 parts of the absorbent system. After a meal containing only 
 starchy or albuminoid substances, there is no apparent change in 
 the character of their contents. But after a meal containing fatty 
 matters, these substances are taken up by the absorbents of the 
 intestine, which then become filled with the white chylous emul- 
 sion, and assume the appearance of lacteals, (Fig. 48.) It is for 
 this reason that lacteal vessels do not show themselves upon the 
 stomach nor upon the first few inches of the duodenum ; because 
 oleaginous matters, as we have seen, are not digested in the stomach, 
 but only after they have entered the intestine and passed the orifice 
 of the pancreatic duct. 
 
 The presence of chyle in the lacteals is, therefore, not a con- 
 stant, but only a periodical phenomenon. The fatty substances 
 constituting the chyle begin to be absorbed during the process of 
 
136 
 
 ABSORPTION. 
 
 digestion, as soon as they have been disintegrated and emulsioned 
 by the action of the intestinal fluids. As digestion proceeds, they 
 accumulate in larger quantity, and gradually fill the whole lacteal 
 
 Fig. 43. 
 
 LACTEALS AXD Lr-MPHATICS. 
 
 system and the thoracic duct. As they are discharged into the 
 subclavian vein, and mingled with the blood, they can still be dis- 
 tinguished in the circulating fluid, as a mixture of oily molecules 
 and granules, between the orifice of the thoracic duct and the right 
 side of the heart. While passing through the pulmonary circula- 
 
ABSORPTIOlSr. 137 
 
 tion, however, they disappear. Precisely what becomes of them, 
 or what particular chemical changes they undergo, is not certainly 
 known. They are, at all events, so altered in the blood, while 
 passing through the lungs, that they lose the form of a fatty emul- 
 sion, and are no longer to be recognized by the usual tests for 
 oleaginous substances. 
 
 The absorption of fat from the intestine is not, however, exclu- 
 sively performed by the lacteals. Some of it is also taken up, 
 under the same form, by the bloodvessels. It has been ascertained 
 by the experiments of Bernard' that the blood of the mesenteric 
 veins, in the carnivorous animals, contains, during intestinal diges- 
 tion, a considerable amount of fatty matter in a state of minute 
 subdivision. Other observers, also (Lehmann, Schultz, Simon), have 
 found the blood of the portal vein to be considerably richer in fat 
 than that of other veins, particularly while intestinal digestion is 
 going on with activity. In birds, reptiles, and fish, furthermore, 
 according to Bernard, the intestinal lymphatics are never filled 
 with opaque chyle, but only with a transparent lymph; so that these 
 animals may be said to be destitute of lacteals, and in them the fatty 
 substances, like other alimentary materials, are taken up altogether 
 by the bloodvessels. In quadrupeds, on the other hand, and in 
 the human subject, the absorption of fat is accomplished both by 
 the bloodvessels and the lacteals. A certain portion is taken up 
 by the former, while the superabundance of the fatty emulsion is 
 absorbed by the latter. 
 
 A difficulty has long been experienced in accounting for the absorp- 
 tion of fat from the intestine, owing to its being considered as a non- 
 endosmotic substance; that is, as incapable, in its free or undissolved 
 condition, of penetrating and passing through an animal membrane 
 by endosmosis. It is stated, indeed, that if a fine oily emulsion be 
 placed on one side of an animal membrane in an endosmometer, 
 and pure water on the other, the water will readily penetrate the 
 substance of the membrane, while the oily particles cannot be made 
 to pass, even under a high pressure. Though this be true, how- 
 ever, for pure water, it is not true for slightly alkaline fluids, like 
 the serum of the blood and the lymph. This has been demon- 
 strated by the experiments af Matteucci, in which he made an 
 emulsion with an alkaline fluid containing 43 parts per thou- 
 sand of caustic potass. Such a solution has no perceptible alkaline 
 
 ' Lemons de Physiologic Experiinentale. Paris, 1'56, p. 325. 
 
138 
 
 ABSORPTION. 
 
 taste, and its action on reddened litmus paper is about equal to 
 that of the lymph and chyle. If this emulsion were placed in an 
 endosmometer, together with a watery alkaline solution of similar 
 strength, it was found that the oily particles penetrated through the 
 animal membrane without much difficulty, and mingled with the fluid 
 on the opposite side. Although, therefore, we cannot explain the 
 exact mechanism of absorption in the case of fat, still we know 
 
 that it is not in opposition to 
 ^^' * the ordinary phenomena of 
 
 endosmosis; for endosmosis 
 will take place with a fatty 
 emulsion, provided the fluids 
 used in the experiment be 
 slightly alkaline in reaction. 
 It is, accordingly, by a pro- 
 cess of endosmosis, or imbi- 
 bition, that the villi take up 
 the digested fatty substances. 
 There are no open orifices 
 or canals, into which the oil 
 penetrates; but it passes di- 
 rectly into and through the 
 substance of the villi. The 
 epithelial cells covering the external surface of the villus are the first 
 active agents in this absorption. In the intervals of digestion (Fig. 
 
 44) these cells are but slightly 
 
 Intestinal Epithelium; from the Dog, -while 
 fasting. 
 
 Fig. 45. 
 
 Intestinal Epithelium; from the Dog, dur- 
 ing the digestion of fat. 
 
 granular and nearly trans- 
 parent in appearance. But if 
 examined during the diges- 
 tion and absorption of fat 
 (Fig, 45), their substance is 
 seen to be crowded with oily 
 particles, which they have 
 taken up from the intestinal 
 cavity by absorption. The 
 oily matter then passes on- 
 ward, penetrating deeper and 
 deeper into the substance of 
 the villus, until it is at last 
 received by the capillary ves- 
 sels and lacteals in its centre. 
 
ABSOEPTION. 139 
 
 The fatty substances taken up by the portal vein, like those ab- 
 sorbed by the lacteals, do not at once enter the general circulation, 
 but pass first through the capillary system of the liver. Thence 
 they are carried, with the blood of the hepatic vein, to the right 
 side of the heart, and subsequently through the capillary system of 
 the lungs. During this passage they become altered in character, 
 as above described, and lose for the most part the distinguishing 
 characteristics of oily matter, before they have passed beyond the 
 pulmonary circulation. 
 
 But as digestion proceeds, an increasing quantity of fatty matter 
 finds its way, by these two passages, into the blood; and a time at 
 last arrives when the whole of the fat so introduced is not destroyed 
 during its passage through the lungs. Its absorption taking place 
 at this time more rapidly than its decomposition, it begins to ap- 
 pear,, in moderate quantity, in the blood of the general circulation ; 
 and, lastly, when the intestinal absorption is at its point of greatest 
 activity, it is found in considerable abundance throughout the 
 entire vascular system. At this period, some hours after the inges- 
 tion of food rich in oleaginous matters, the blood of the general 
 circulation everywhere contains a superabundance of fat, derived 
 from the digestive process. If blood be then drawn from the 
 veins or arteries in any part of the body, it will present the pecu- 
 liar appearance known as that of " chylous" or " milky" blood. 
 After the separation of the clot, the serum presents a turbid ap- 
 pearance; and the fatty substances, which it contains, rise to the 
 top after a few hours, and cover its surface with a partially opaque 
 and creamy-looking pellicle. This appearance has been occasion- 
 ally observed in the human subject, particularly in bleeding for 
 apoplectic attacks occurring after a full meal, and has been mis- 
 taken, in some instances, for a morbid phenomenon. It is, however, 
 a perfectly natural one, and depends simply on the rapid absorp- 
 tion, at certain periods of digestion, of oleaginous substances from 
 the intestine. It can be produced at will, at any time, in the dog, 
 by feeding him with fat meat, and drawing blood, seven or eight 
 hours afterward, from the carotid artery or the jugular vein. 
 
 This state of things continues for a varying length of time, 
 according to the amount of oleaginous matters contained in the 
 food. When digestion is terminated, and the fat ceases to be intro- 
 duced in unusual quantity into the circulation, its transformation 
 and decomposition continuing to take place in the blood, it dis- 
 appears gradually from the veins, arteries, and capillaries of the 
 
140 ABSORPTION. 
 
 general system; and, finally, when the whole of the fat has been 
 disposed of by the nutritive processes, the serum again becomes 
 transparent, and the blood returns to its ordinary condition. 
 
 In this manner the nutritive elements of the food, prepared for 
 absorption by the digestive process, are taken up into the circulation 
 under the different forms of albuminose, sugar, and chyle, and accu- 
 mulate as such, at certain times, in the blood. But these conditions 
 are only temporary, or transitional. The nutritive materials soon 
 pass, by catalytic transformation, into other forms, and become 
 assimilated to the pre-existing elements of the circulating fluid. 
 They thus accomplish finally the whole object of digestion ; which 
 is to replenish the blood by a supply of new materials from without. 
 There are, however, two other intermediate processes, taking place 
 partly in the liver and partly in the intestine, at about the same 
 time, and having for their object the final preparation and perfec- 
 tion of the circulating fluid. These two processes require to be 
 studied, before we can pass on to the particular description of the 
 blood itself. They are : 1st, the secretion and reabsorption of the 
 bile ; and 2d, the production of sugar in the liver, and its subse- 
 quent decomposition in the blood. 
 
THE BILE. 141 
 
 CHAPTER VIII. 
 
 THE BILE. 
 
 The bile is more easily obtained in a state of purity than any 
 other of the secretions which find their way into the intestinal 
 canal, owing to the existence of a gall-bladder in which it accu- 
 mulates, and from which it may be readily obtained without any 
 other admixture than the mucus of the gall-bladder itself. Not- 
 withstanding this, its study has proved an unusually difficult one. 
 This difficulty has resulted from the peculiar nature of the biliary 
 ingredients, and the readiness with which they become altered by 
 chemical manipulation; and it is, accordingly, only quite recently 
 that we have arrived at a correct idea of its real constitution. 
 
 The bile, as it comes from the gall-bladder, is a somewhat viscid 
 and glutinous fluid, varying in color and specific gravity according 
 to the species of animal from which it is obtained. Human bile is 
 of a dark golden brown color, ox bile of a greenish yellow, pig's 
 bile of a nearly clear yellow, and dog's bile of a deep brown. We 
 have found the specific gravity of human bile to be 1018, that of 
 ox bile 1024, that of pig's bile 1030 to 1036. The reaction of the 
 bile with test-paper cannot easily be determined ; since it has only 
 a bleaching or decolorizing effect on litmus, and does not turn it 
 either blue or red. It is probably either neutral or very slightly 
 alkaline. A very characteristic physical property of the bile is 
 that of frothing up into a soap-like foam when shaken in a test- 
 tube, or when air is forcibly blown into it through a small glass 
 tube or blowpipe. The bubbles of foam, thus produced, remain 
 for a long time without breaking, and adhere closely to each other 
 and to the sides of the glass vessel. 
 
 The following is an analysis of the bile of the ox, based on the 
 calculations of Berzelius, Frerichs, and Lehmann : — 
 
142 THE BILE. 
 
 Composition of Ox Bile. 
 
 Water 880.00 
 
 Gljko-cholate of soda ........ \ 
 
 Tauro-cholate " " } ^^'^^ 
 
 Biliverdine ..........") 
 
 Fats 
 
 Oleates, margarates, and stearates of soda and potass . 
 Cholesterin ......... 
 
 Chloride of sodium ........ ^ 
 
 Phosphate of soda ....... 
 
 " " lime 
 
 " " magnesia ...... 
 
 Carbonates of soda and potass . . . • . . 
 
 Mucus of the gall-bladder . . . . . . . .1.34 
 
 1- 13.42 
 
 15.24 
 
 1000.00 
 
 Biliverdine. — Of the above mentioned ingredients, hiliverdine 
 is peculiar to the bile, and therefore important, though not pre- 
 sent in large quantity. This is the coloring matter of the bile. 
 It is, like the other coloring matters, an uncrystallizable organic 
 substance, containing nitrogen, and yielding to ultimate analysis a 
 small quantity of iron. It exists in such small quantity in the bile 
 that its exact proportion has never been determined. It is formed, 
 so far as can be ascertained, in the substance of the liver, and does 
 not pre-exist in the blood. It may, however, be reabsorbed in 
 cases of biliary obstruction, when it circulates with the blood and 
 stains nearly all the tissues and fluids of the body, of a peculiar 
 lemon yellow color. This is the symptom which is characteristic 
 of jaundice. 
 
 Cholesterin (CjjHgjO). — This is a crystallizable substance which 
 resembles the fats in many respects ; since it is destitute of nitrogen, 
 readily inflammable, soluble in alcohol and ether, and entirely in- 
 soluble in water. It is not saponifiable, however, by contact with 
 the alkalies, and is distinguished on this account from the ordinary 
 fatty substances. It occurs, in a crystalline form, mixed with color- 
 ing matter, as an abundant ingredient in most biliary calculi ; and 
 is found also in different regions of the body, forming a part of 
 various morbid deposits. We have met with it in the fluid of 
 hydrocele, and in the interior of many encysted tumors. The 
 crystals of cholesterin (Fig. 46) have the form of very thin, color- 
 less, transparent, rhomboidal plates, portions of which are often 
 cut out by lines of cleavage parallel to the sides of the crystal. 
 They frequently occur deposited in layers, in which the outlines of 
 
THE BILE. 
 
 143 
 
 Cholesterin is not formed in the 
 
 Fig. 46. 
 
 the subjacent crystals show very distinctly through the substance 
 
 of those which are placed above 
 
 liver, but originates in the 
 
 substance of the brain and 
 
 nervous tissue, from which 
 
 it may be extracted in large 
 
 quantity by the action of 
 
 alcohol. From these tissues 
 
 it is absorbed by the blood, 
 
 then conveyed to the liver, 
 
 and discharged with the bile. 
 
 The fatty substances and 
 inorganic saline ingredients 
 of the bile require no special 
 description. 
 
 C HO LESTER IX from an Encysted Tumor. 
 
 Biliary Salts. — By far 
 the most important and characteristic ingredients of this secretion 
 are the two saline substances mentioned above as the glyko-cholate 
 and tauro-cholate of soda. These substances were first discovered 
 by Strecker, in 1848, in the bile of the ox. They are both freely 
 soluble in water and in alcohol, but insoluble in ether. One of 
 them, the tauro-cholate, has the property, when itself in solution 
 in water, of dissolving a certain quantity of fat ; and it is probably 
 owing to this circumstance that some free fat is present in the bile. 
 The two biliary substances are obtained from ox-bile in the follow- 
 ing manner : — 
 
 The bile is first evaporated to dryness by the water-bath. The 
 dry residue is then pulverized and treated with absolute alcohol, in 
 the proportion of at least 5j of alcohol to every five grains of dry 
 residue. The filtered alcoholic solution has a clear yellowish color. 
 It contains, beside the glyko-cholate and tauro-cholate of soda, the 
 coloring matter and more or less of the fats originally present in 
 the bile. On the addition of a small quantity of ether, a dense, 
 whitish precipitate is formed, which disappears again on agitating 
 and thoroughly mixing the fluids. On the repeated addition of 
 ether, the precipitate again falls down, and when the ether has been 
 added in considerable excess, six to twelve times the volume of the 
 alcoholic solution, the precipitate remains permanent, and the whole 
 mixture is filled with a dense, whitish, opaque deposit, consisting of 
 
144 
 
 THE BILE. 
 
 the glyko-cholate and tauro-cholate of soda, thrown down under 
 the form of heavy flakes and granules, part of which subside to 
 the bottom of the test-tube, while part remain for a time in suspen- 
 sion. Gradually these flakes and granules unite with each other 
 and fuse together into clear, brownish-yellow, oily, or resinous- 
 looking drops. At the bottom of the test-tube, after two or three 
 hours, there is usually collected a nearly homogeneous layer of 
 this deposit, while the remainder continues to adhere to the sides 
 of the glass in small, circular, transparent drops. The deposit is 
 semi-fluid in consistency, and sticky, like Canada balsam or half- 
 rnelted resin ; and it is on this account that the ingredients compos- 
 ing it have been called the " resinous matters" of the bile. They 
 have, however, no real chemical relation with true resinous bodies, 
 since they both contain nitrogen, and differ from resins also in 
 other important particulars. 
 
 At the end of twelve to twenty-four hours, the glyko-cholate of 
 soda begins to crystallize. The crystals radiate from various points 
 in the resinous deposit, and shoot upward into the supernatant 
 fluid, in white, silky bundles. (Fig, 47.) If some of these crystals 
 
 Fig. 47 
 
 Fig. 48. 
 
 Ox -BILE, extracted with absolute 
 alcohol and precipitated with ether. 
 
 Gt.tko-cholate of Soda from Ox-bile, 
 after two days' crystallization. At the lower part of 
 the figure the crystals are melting into drops, from the 
 evaporation of the ether and absorption of moisture. 
 
 be removed and examined by the microscope, they are found to be 
 of a very delicate acicular form, running to a finely pointed 
 extremity, and radiating, as already mentioned, from a central 
 
THE BILE. 
 
 145 
 
 point. (Fig. 48.) As the ether evaporates, the crystals absorb 
 moisture from the air, and melt up rapidly into clear resinous 
 drops; so that it is difficult to keep them under the microscope 
 long enough for a correct drawing and measurement. The crystal- 
 lization in the test-tube goes on after the first day, and the crystals 
 increase in quantity for three or four, or even five or six days, until 
 the whole of the glyko-cholate of soda present has assumed the 
 solid form. The tauro-cholate, however, is uncrystallizable, and 
 remains in an amorphous condition. If a portion of the deposit be 
 now removed and examined by the microscope, it is seen that the 
 crystals of gl3^ko-cholate of 
 soda have increased conside- ^^' 
 
 rably in thickness (Fig. 49), 
 so that their transverse dia- 
 meter may be readily esti- 
 mated. The uncrystallizable 
 tauro-cholate appears under 
 the form of circular drops, 
 varying considerably in size, 
 clear, transparent, strongly 
 refractive, and bounded by 
 a dark, well-defined outline. 
 These drops are not to he distin- 
 guished, by any of their ojyiical 
 properties, from oil-glohides, 
 as they usually appear under 
 the microscope. They have 
 the same refractive power, 
 the same dark outline and bright centre, and the same degree of 
 consistency. They would consequently be liable at all times to be 
 mistaken for oil-globules, were it not for the complete dissimilarity 
 of their chemical properties. 
 
 Both the glyko-cholate and tauro-cholate of soda are very freely 
 soluble in water. If the mixture of alcohol and ether be poured 
 ofl' and distilled water added, the deposit dissolves rapidly and 
 completely, with a more or less distinct yellowish color, accord- 
 ing to the proportion of coloring matter originally present in the 
 bile. The two biliary substances present in the watery solution 
 may be separated from each other by the following means. On 
 tlie addition of acetate of lead, the glyko-cholate of soda is decom- 
 posed, and precipitates as a glyko-cholate of lead. The precipitate, 
 10 
 
 Glyko-cholate and Tauro-cholate of 
 Soda, from Os-bile, after six days' crystalliza- 
 tion. The glyko-cholate is crystallized ; the tauro- 
 cliolate is in fluid drops. 
 
146 THE BILE. 
 
 separated bj filtration from the remaining fluid, is then decomposed 
 in turn by carbonate of soda, and the original glyko-cholate of soda 
 reproduced. The filtered fluid which remains, and which contains 
 the tauro-cholate of soda, is then treated with subacetaie of lead, 
 which precipitates a tauro-cholate of lead. This is separated by 
 filtration, washed, and decomposed again by carbonate of soda, as 
 in the former case. 
 
 The two biliary substances in ox bile may, therefore, be dis- 
 tinguished by their- reactions with the salts of lead. Both are 
 precipitable by the subacetate; but the glyko-cholate of soda is 
 precipitable also by the acetate, while the tauro-cholate is not so. 
 If subacetate of lead, therefore, be added to the mixed watery solu- 
 tion of the two substances, and the whole filtered, the subsequent 
 addition of acetate of lead to the filtered fluid will produce no pre- 
 cipitate, because both the biliary matters have been entirely thrown 
 down with the deposit; but if the acetate of lead be first added, it 
 will precipitate the glyko-cholate alone, and the tauro-cholate may 
 afterward be thrown down separately by the subacetate. 
 
 These two substances, examined separately, have been found to 
 possess the following properties : — 
 
 Glylw-cholate of soda (^diOfi^^^^O^^ crystallizes, when precipi- 
 tated by ether from its alcoholic solution, in radiating bundles of 
 fine white silky needles, as above described. It is composed of 
 soda, united with a peculiar acid of organic origin, viz., glyko-cholic 
 acid (C52li42-^0,i,HO). This acid is crystallizable and contains nitro- 
 gen, as shown by the above formula, which is that given by Leh- 
 man n. If boiled for a long time with a dilute solution of potass, 
 glyko-cholic acid is decomposed with the production of two new 
 substances; the first a non-nitrogenous acid body, cholic acid 
 (C48H3g09,IIO) ; the second a nitrogenous neutral body, glycine 
 (C4H5NOJ. Hence the name, glyko-cholic acid, given to the 
 original substance, as if it were a combination of cholic acid with 
 glycine. In reality, however, these two substances do not exist 
 originally in the glyko-cholic acid, but are rather new combinations 
 of its elements, produced by long boiling, in contact with potass 
 and water. They are not, therefore, to be regarded as, in any way, 
 natural ingredients of the bile, and do not throw any light on the 
 real constitution of glyko-cholic acid. 
 
 Tauro-cholate of soda (^diO^G^^^^^^O^^ is also a very abundant 
 ingredient of the bile. It is said by Robin and YerdeiP that it is 
 
 ' Chimie Anatomique et Physiologique, vol. ii. p. 473. 
 
THE BILE. 147 
 
 not crystallizable, owing probably to its not having been separated 
 as yet in a perfectly pure condition. Lehmann states, on the con- 
 trary, that it may crystallize,' when kept for a long time in contact 
 with ether. We have not been able to obtain this substance, how- 
 ever, in a crystalline form. Its acid constituent, tauro-cliolic acid^ 
 is a nitrogenous body, like glyko-cholic acid, but differs from the 
 latter by containing in addition two equivalents of sulphur. By 
 long boiling in a dilute solution of potass, it is decomposed with 
 the production of two other substances; the first of them the same 
 acid body mentioned above as derived from the glyko-cholic, viz., 
 cholic acid; and the second a new nitrogenous neutral body, viz., 
 taurine {Q^^'^'^f)^. The same remark holds good with regard to 
 these two bodies, that we have already made in respect to the sup- 
 posed constituents of glyko-cholic acid. Neither cholic acid nor 
 taurine can be properly regarded as really ingredients of tauro- 
 cholic acid, but only as artificial products resulting from its altera- 
 tion and decomposition. 
 
 The glyko-cholates and tauro-cholates are formed, so far as we 
 know, exclusively in the liver; since they have not been found in 
 the blood, nor in any other part of the body, in healthy animals; 
 nor even, in the experiments of Kunde, Moleschott, and Lehmann 
 on frogs,^ after the entire extirpation of the liver, and consequent 
 suppression of the bile. These substances are, therefore, produced 
 in the glandular cells of the liver, by transformation of some other 
 of their ingredients. They are then exuded in a soluble form, as 
 part of the bile, and finally discharged by the excretory hepatic 
 ducts. 
 
 The two substances described above as the tauro-cholate and 
 glyko-cholate of soda exist, properly speaking, only in the bile of 
 the ox, where they were first discovered by Strecker. In examin- 
 ing the biliary secretions of different species of animals, Strecker 
 found so great a resemblance between them, that he was disposed 
 to regard their ingredients as essentially the same. Having estab- 
 lished the existence in ox bile of two peculiar substances, one 
 crystallizable and non-sulphurous (glyko-cholate), the other uncrys- 
 tallizable and sulphurous (tauro-cholate), he was led to consider 
 the bile in' all species of animals as containing the same substances, 
 and as differing only in the relative quantity in which the two 
 
 ' Physiological Chemistry, Phil, ed., vol. i. p. 209. 
 
 2 Lehmann's Physiological Chemistry, Phil, ed., vol. i. p. 476. 
 
148 
 
 THE BILE. 
 
 Fig. 50. 
 
 were present. The only exception to this was supposed to be pig's 
 bile, in which Strecker found a peculiar organic acid, the " hyo- 
 cbolic" or " hjo-cholinic" acid, in combination with soda as a base. 
 The above conclusion of his, however, was not entirely correct. 
 It is true that the bile of all animals, so far as examined, contains 
 peculiar substances, which resemble each other in being freely 
 soluble in water, soluble in absolute alcohol, and insoluble in ether; 
 and in giving also a peculiar reaction with Pettenkofer's test, to be 
 described presently. But, at the same time, these substances pre- 
 sent certain minor differences in different animals, which show them 
 not to be identical. 
 
 In dog's bile, for example, there are, as in ox bile, two substances 
 precipitable by ether from their alcoholic solution; one crystalliz- 
 able, the other not so. But the former of these substances crystallizes 
 much more readily than the glyko-cholate of soda from ox-bile. Dog's 
 bile will not unfrequently begin to crystallize freely in five to six 
 hours after precipitation by ether (Fig. 50); while 
 in ox-bile it is usually twelve, and often twenty- 
 four or even forty-eight hours before crystalliza- 
 tion is fully established. But it is more particu- 
 larly in their reaction with the salts of lead that 
 the difference between these substances becomes 
 manifest. For while the crystallizable substance 
 of ox-bile is precipitated by acetate of lead, that 
 of dog's bile is not affected by it. If dog's bile 
 be evaporated to dryness, extracted with absolute 
 alcohol, the alcoholic solution precipitated by 
 ether, and the ether precipitate then dissolved 
 in water, the addition of acetate of lead to the 
 watery solution produces not the slightest tur- 
 bidity. If subacetate of lead be then added in 
 excess, a copious precipitate falls, composed of 
 both the crystallizable and uncrystallizable sub- 
 stances. If the lead precipitate be then separated 
 by filtration, washed, and decomposed, as above 
 described, by carbonate of soda, the watery solu- 
 tion will contain the re-formed soda salts of the 
 bile. The watery solution may then be evaporated to dryness, 
 extracted with absolute alcohol, and the alcoholic solution precipi- 
 tated by ether ; when the ether precipitate crystallizes partially 
 after a time, as in fresh bile. Both the biliary matters of dog's bile 
 
 Dog's Bile, extract- 
 ed with absolute alcohol 
 and precipitated with 
 ether. 
 
THE BILE, 
 
 149 
 
 Fig. 51. 
 
 are therefore precipitable by sabacetateof lead, but neither of them 
 by the acetate. Instead of calling them, consequently, glykocholate 
 and tauro-cholate of soda, we shall speak of them simply as the 
 "crystalline" and "resinous" biliary substances. 
 
 In cat's bile, the biliary substances act very much as in dog's 
 bile. The ether- precipitate of the alcoholic solution contains here 
 also a crystalline and a resinous substance; both of which are 
 precipitable from their watery solution by subacetate of lead, but 
 neither of them by the acetate. 
 
 In pig's bile, on the other hand, there is no crystallizable sub- 
 stance, but the ether-precipitate is altogether resinous in appearance. 
 Notwithstanding this, its watery solution. precipitates abundantly by 
 both the acetate and subacetate of lead. 
 
 In human bile, again, there is no crystallizable substance. We 
 have found that the dried bile, extracted with absolute alcohol, 
 makes a clear, brandy red solution, which precipitates abundantly 
 with ether in excess ; but the ether-precipitate, if allowed to stand, 
 shows no sign of crystallization, even at the end 
 of three weeks (Fig. 51). If the resinous pre- 
 cipitate be separated by decantation and dissolved 
 in water, it precipitates, as in the case of pig's 
 bile, by both the acetate and subacetate of lead. 
 This might, perhaps, be attributed to the pre- 
 sence of two different substances, as in ox-bile, 
 one precipitated by the acetate, the other by the 
 subacetate of lead. Such, however, is not the 
 case. For if the watery solution be precipitated 
 by the acetate of lead and then filtered, the 
 filtered fluid gives no precipitate afterward by the 
 subacetate ; and if first precipitated by the sub- 
 acetate, it gives no precipitate after filtration by 
 the acetate. The entire biliary ingredients, 
 therefore, of human bile are precipitated by both 
 or either of the salts of lead. 
 
 Dift'erent kinds of bile vary also in other re- 
 spects; as, for example, their specific gravity, 
 the depth and tinge of their color, the quantity 
 of fat which they contain, &c. &c. We have 
 already mentioned the variations in color and specific gravity. 
 The alcoholic solution of dried ox-bile, furthermore, does not pre- 
 cipitate at all on the addition of water ; while that of human bile, 
 
 Human Bile, ex- 
 tracted with absolute 
 alcohol and precipitat- 
 ed by ether. 
 
150 THE BILE. 
 
 of pig's bile, and of dog's bile precipitate abundantly with distilled 
 water, owing to the quantity of fat which they hold in solution. 
 These variations, however, are of secondary importance compared 
 with those which we have already mentioned, and which show that 
 the crystalline and resinous substances in different kinds of bile, 
 though resembling each other in very many respects, are yet in 
 reality far from being identical. 
 
 TESTS FOE BILE. 
 
 In investigating the physiology of any animal fluid it is, of 
 course, of the first importance to have a convenient and reliable 
 test by which its presence may be detected. For a long time the 
 only test employed in the case of bile, was that which depended on 
 a change of color produced hy oxidizing substances. If the bile, for 
 example, or a mixture containing bile, be exposed in an open 
 glass vessel for a few hours, the upper layers of the fluid, which 
 are in contact with the atmosphere, gradually assume a greenish 
 tinge, which becomes deeper with the length of time which elapses, 
 and the quantity of bile existing in the fluid. Nitric acid, added to 
 a mixture of bile and shaken up, produces a dense precipitate 
 which takes a bright grass-green hue. Tincture of iodine produces 
 the same change of color, when added in small quantity ; and pro- 
 bably there are various other substances which would have the 
 same effect. It is by this test that the bile has so often been recog- 
 nized in the urine, serous effusions, the solid tissues, kc, in cases 
 of jaundice. But it is very insufficient for anything like accurate 
 investigation, since the appearances are produced simply by the 
 action of an oxidizing agent on the coloring matter of the bile. A 
 green color produced by nitric acid does not, therefore, indicate the 
 presence of the biliary substances proper, but only of the biliver- 
 dine. On the other hand, if the coloring matter be absent, the 
 biliary substances themselves cannot be detected by it. For if the 
 biliary substances of dog's bile be precipitated by ether from an 
 alcoholic solution, dissolved in w^ater and decolorized by animal 
 charcoal, the colorless watery solution will then give no green 
 color on the addition of nitric acid or tincture of iodine, though it 
 may precipitate abundantly by subacetate of lead, and give the 
 other reactions of the crystalline and resinous biliary matters in a 
 perfectly distinct manner. 
 
TESTS FOR BILE. 151 
 
 Petienkofer'' s Test. — This is undoubtedly the best test yet pro- 
 posed for the detection of the biliary substances. It consists in 
 mixing with a watery solution of the bile, or of the biliary sub- 
 stances, a little cane sugar, and then adding sulphuric acid to the 
 mixture until a red, lake or purple color is produced. A solution 
 may be made of cane sugar, in the proportion of one part of sugar to 
 four parts of water, and kept for use. One drop of this solution is 
 mixed with the suspected fluid, and the sulphuric acid then imme- 
 diately added. On first dropping in the sulphuric acid, a whitish 
 precipitate falls, which is abundant in the case of ox-bile, less so in 
 that of the dog. This precipitate redissolves in a slight excess of 
 sulphuric acid, which should then continue to be added until the 
 mixture assumes a somewhat syrupy consistency and an opalescent 
 look, owing to the development of minute bubbles of air. A red 
 color then begins to show itself at the bottom of the test-tube, and 
 afterward spreads through the mixture, until the whole fluid is of 
 a clear, bright, cherry red. This color gradually changes to a lake, 
 and finally to a deep, rich, opaque purple. If three or four vol- 
 umes of water be then added to the mixture, a copious precipitate 
 falls down, and the color is destroyed. 
 
 Various circumstances modify, to some extent, the rapidity and 
 distinctness with which the above changes are produced. If the 
 biliary substances be present in large quantity, and nearly pure, 
 the red color shows itself at once, after adding an equal volume of 
 sulphuric acid, and almost immediately passed into a strong purple. 
 If they be scanty, on the other hand, the red color may not show 
 itself for seven or eight minutes, nor the purple under twenty 
 or twenty-five minutes. If foreign matters, again, not of a biliary 
 nature, be also present, they are apt to be acted on by the sulphuric 
 acid, and, by becoming discolored, interfere with the clearness and 
 brilliancy of the tinges produced. On this account it is indispen- 
 sable, in delicate examinations, to evaporate the suspected fluid to 
 dryness, extract the dry residue with absolute alcohol, precipitate 
 the alcoholic solution with ether, and dissolve the ether precipitate 
 in water before applying the test. In this manner, all foreign sub- 
 stances which might do harm will be eliminated, and the test will 
 succeed without difficulty. 
 
 It must not be forgotten, furthermore, that the sugar itself is 
 liable to be acted on and discolored by sulphuric acid when added 
 in excess, and may therefore by itself, give rise to confusion. A little 
 care and practice, however, will enable the experimenter to avoid 
 
152 THE BILE. 
 
 all chance of deception from this source. AVhen sulphuric acid is 
 mixed with a watery solution containing cane sugar, after it has 
 been added in considerable excess, a yellowish color begins to show 
 itself, owing to the commencing decomposition of the sugar. This 
 color gradually deepens until it has become a dark, dingy, muddy 
 brown ; but there is never at any time any clear red or purple 
 color unless biliary matters be present. If the bile be present in 
 but small quantity, the colors produced by it may be modified and 
 obscured by the dingy yellow and brown of the sugar; but even 
 this difficulty may be avoided by paying attention to the following 
 precautions. In the first place, only very little sugar should be 
 added to the suspected fluid. In the second place, the sulphuric 
 acid should be added very gradually, and the mixture closely 
 watched to detect the first changes of color. If bile be present, the 
 red color peculiar to it is always produced before the yellowish 
 tinge which indicates the decomposition of the sugar. When the 
 biliary matters, therefore, are present in small quantity, the addi- 
 tion of sulphuric acid should be stopped at that point, and the 
 colors, though faint, will then remain clear, and give unmistakable 
 evidence of the presence of bile. 
 
 The red color alone is not sufficient as an indication of bile It 
 is in fact only the commencement of the change which indicates the 
 biliary matters. If these matters be present, the color passes, as 
 we have already mentioned, first into a lake, then into a purple ; 
 and it is this lake and purple color alone which can be regarded as 
 really characteristic of the biliary reaction. 
 
 It is important to observe that Pettenkofer's reaction is produced 
 by the presence of either or both of the biliary substances proper ; 
 and is not at all dependent on the coloring matter of the bile. For 
 if the two biliary substances, crystalline and resinous, be extracted 
 by the process above described, and, after being dissolved in water, 
 decolorized with animal charcoal, the watery solution will still give 
 Pettenkofer's reaction perfectly, though no coloring matter be pre- 
 sent, and though no green tinge can be produced by the addition 
 of nitric acid or tincture of iodine. If the two biliary substances 
 be then separated from each other, and tested in distinct solutions, 
 each solution will give the same reaction promptly and completely. 
 
 Various objections have been urged against this test. It has 
 been stated to be uncertain and variable in its action. Eobin and 
 Verdeil' say that its reactions "do not belong exclusively to the 
 
 » Op cit., vol. ii. p. 468. 
 
VARIATIONS AND FUNCTIONS OF BILE. 153 
 
 bile, and may therefore give rise to mistakes." Some fatty sub- 
 stances and volatile oils (olein, oleic acid, oil of turpentine, oil of 
 caraway) have been stated to produce similar red and violet colors, 
 when treated with sugar and sulphuric acid. These objections, 
 however, have not much, if any, practical weight. The test no doubt 
 requires some care and practice in its application, as we have already 
 pointed out ; but this is the case also, to a greater or less extent, 
 with nearly all chemical tests, and particularly with those for sub- 
 stances of organic origin. No other substance is, in point of fact, 
 liable to be met with in the intestinal fluids or the blood, which 
 would simulate the reactions of the biliary matters. We have 
 found that the fatty matters of the chyle, taken from the thoracic 
 duct, do not give any coloration which would be mistaken for that 
 of the bile. When the volatile oils (caraway and turpentine) are 
 acted on by sulphuric acid, a red color is produced which after- 
 ward becomes brown and blackish, and a peculiar, tarry, empyreu- 
 raatic odor is developed at the same time ; but we do not get the 
 lake and purple colors spoken of above. Finally, if the precaution 
 be observed — first of extracting the suspected matters with absolute 
 alcohol, then precipitating with ether and dissolving the precipitate 
 in water, no ambiguity could result from the presence of any of the 
 above substances. 
 
 Pettenkofer's test, then, if used with care, is extremely useful, and 
 may lead to many valuable results. Indeed, no other test than this 
 can be at all relied on to determine the presence or absence of the 
 biliary substances proper. 
 
 VARIATIONS AND FUNCTIONS OF BILE. 
 
 With regard to the entire quantity of bile secreted daily, we have 
 had no very positive knowledge, until the experiments of Bidder 
 and Schmidt, published in 1852.* These experiments were per- 
 formed on cats, dogs, sheep, and rabbits, in the following manner. 
 The abdomen was opened, and a ligature placed upon the ductus 
 communis choledochus, so as to prevent the bile finding its way 
 into the intestine. An opening was then made in the fundus of 
 the gall-bladder, by which the bile was discharged externally. The 
 bile, so discharged, was received into previously weighed vessels, 
 
 ' Verdaungssaefte und StoffwechseL Leipzig, 1852. 
 
154: THE BILE. 
 
 and its quantity accurately determined. Each observation usually 
 occupied about two hours, during which period the temporary 
 fluctuations occasionally observable in the quantity of bile dis- 
 charged were mutually corrected, so fai; as the entire result was 
 concerned. The animal was then killed, weighed and carefully 
 examined, in order to make sure that the biliary duct had been 
 securely tied, and that no inflammatory alteration had taken place 
 in the abdominal organs. The observations were made at very 
 different periods after the last meal, so as to determine the influence 
 exerted by the digestive process upon the rapidity of the secretion. 
 The average quantity of bile for twenty-four hours was then calcu- 
 lated from a comparison of the above results ; and the quantity of 
 its solid ingredients was also ascertained in each instance by eva- 
 porating a portion of the bile in the water-bath, and weighing the 
 dry residue. 
 
 Bidder and Schmidt found in this way that the daily quantity of 
 bile varied considerably in different species of animals. It was 
 very much greater in the herbivorous animals used for experiment 
 than in the carnivora. The results obtained by these observers 
 are as follows .• — 
 
 For every pound weight of the entire body there is secreted 
 during 24 hours 
 
 Feesh Bile. Dry Residue. 
 
 In the cat 102 grains. 5.712 grains. 
 
 "dog 140 " 6.916 " 
 
 " sheep 178 " 9.408 " 
 
 " rabbit 958 " 17.290 " 
 
 Since, in the human subject, the digestive processes and the 
 nutritive actions generally resemble those of the carnivora, rather 
 than those of the herbivora, it is probable that the daily quantity 
 of bile in man is very similar to that in the carnivorous animals. 
 If we apply to the human subject the average results obtained by 
 Bidder and Schmidt from the cat and dog, we find that, in an adult 
 man, weighing 140 pounds, the daily quantity of the bile will be 
 certainly not less than 16,940 grains, or very nearly 2|- pounds 
 avoirdupois. 
 
 It is a matter of great importance, in regard to the bile, as well 
 as the other intestinal fluids, to ascertain whether it be a constant 
 secretion, like the urine and perspiration, or whether it be intermit- 
 tent, like the gastric juice, and discharged only during the digestive 
 process. In order to determine this point, we have performed the 
 
VARIATIONS AND FUNCTIONS OF BILE. 
 
 155 
 
 following series of experiments on dogs. The animals were kept 
 confined, and killed at various periods after feeding, sometimes 
 by the inoculation of woorara, sometimes by hydrocyanic acid, 
 but most frequently by section of the medulla oblongata. The 
 contents of the intestine were then collected and examined. In 
 all instances, the bile was also taken from the gall-bladder, and 
 treated in the same way, for purposes of comparison. The intes- 
 tinal contents always presented some peculiarities of appearance 
 when treated with alcohol and ether, owing probably to the pre- 
 sence of other substances than the bile ; but they always gave 
 evidence of the presence of biliary matters as well. The biliary 
 substances could almost always be recognized by the microscope 
 in the ether-precipitate of the alcoholic solution ; the resinous 
 substance, under the form of rounded, oily-looking drops (Fig. 
 52), and the other, under the form of crystalline groups, generally 
 presenting the appearance of double bundles of slender, radiat- 
 ing, slightly curved or 
 wavy, needle-shaped crys- 
 tals. These substances, dis- 
 solved in water, gave a pur- 
 ple color with sugar and 
 sulphuric acid. These ex- 
 periments were tried after 
 the animals had been kept 
 for one, two, three, five, six, 
 seven, eight, and twelve 
 days "without food. The 
 result showed that, in all 
 these instances, bile was 
 present in the small intes- 
 tine. It is, therefore, plainly 
 not an intermittent secre- 
 tion, -nor one which is con- 
 cerned exclusively in the digestive process ; but its secretion is con- 
 stant, and it continues to be discharged into the intestine for many 
 days after the animal has been deprived of food. 
 
 Crystalline and Eesinohs Biliary Sub- 
 STANOEs; from Small Intestine of Dog, after two days' 
 fasting. 
 
 The next point of importance to be examined relates to the time 
 after feeding at which the hile passes into the intestine in the greatest 
 abundance. Bidder and Schmidt have already investigated this 
 point in the following manner. They operated, as above described, 
 
156 
 
 THE BILE. 
 
 by tying the common bile-duct, and tlien opening the fundus of the 
 gall-bladder, so as to produce a biliary fistula, by which the whole 
 of the bile was drawn off. By doing this operation, and collecting 
 and weighing the fluid discharged at different periods, they came 
 to the conclusion that the flow of bile begins to increase within 
 two and a half hours after the introduction of food into the stomach, 
 but that it does not reach its maximum of activity till the end of 
 twelve or fifteen hours. Other observers, however, have obtained 
 different results. Arnold,' for example, found the quantity to be 
 largest soon after meals, decreasing again after the fourth hour. 
 Kolliker and Miiller,^- again, found it largest between the sixth and 
 eighth hours. Bidder and Schmidt's experiments, indeed, strictly 
 speaking, show only the time at which the bile is most actively 
 secreted by the liver, but* not when it is actually discharged into 
 the intestine. 
 
 Our own experiments, bearing on this point, were performed on 
 
 dogs, by making a permanent 
 ^^^' ^^' duodenal fistulse, on the same 
 
 plan that gastric fistulee have so 
 often been established for the 
 examination of the gastric juice. 
 (Fig. 53.) An incision was made 
 through the abdominal walls, a 
 short distance to the right of 
 the median line, the floating 
 portion of the duodenum drawn 
 up toward the external wound, 
 opened by a longitudinal inci- 
 sion, and a silver tube, armed 
 at each end with a narrow 
 projecting collar or flange, in- 
 serted into it by one extremity, 
 five and a half inches below the 
 pylorus, and two and a half 
 inches below the orifice of the 
 lower pancreatic duct. The 
 other extremity of the tube was 
 left projecting from the external 
 opening in the abdominal pa- 
 rietes, the parts secured by sutures, and the wound allowed to heal. 
 
 Duodenal Fistula. — a. Stomach. 6. Duo- 
 denum, c, c, c. Pancreas ; its two ducts are seen 
 opening into the duodenum, one near the orifice of 
 the biliary duct, d, the other a short distance 
 lower down. e. Silver tube passing through the 
 abdominal walls and opening into the duodenum. 
 
 ' In Am. Journ. Med. Sci., April, 1856. 
 
 Ibid., April, 1857. 
 
VARIATIONS AND FUNCTIONS OF BILE. 
 
 157 
 
 After cicatrization was complete, and the animal had entirely 
 recovered his healthy condition and appetite, the intestinal fluids 
 were drawn oflf at various intervals after feeding, and their contents 
 examined. This operation, which is rather more difficult than that 
 of making a permanent gastric fistula, is nevertheless exceedingly 
 useful when it succeeds, since it enables us to study, not only the 
 time and rate of the biliary discharge, but also, as mentioned in a 
 previous chapter (Chap. VI.), many other extremely interesting 
 matters connected with intestinal digestion. 
 
 In order to ascertain the absolute quantity of bile discharged 
 into the intestine, and its variations during digestion, the duodenal 
 fluids were drawn off, for fifteen minutes at a time, at various 
 periods after feeding, collected, weighed, and examined separately, 
 as follows: each separate quantity was evaporated to dryness, its 
 dry residue extracted with absolute alcohol, the alcoholic solution 
 precipitated with ether, and the ether-precipitate, regarded as repre- 
 senting the amount of biliary matters present, dried, weighed, and 
 then treated with Pettenkofer's test, in order to determine, as nearly 
 as possible, their degree of purity or admixture. The result of 
 these experiments is given in the following table. At the eigh- 
 teenth hour so small a quantity of fluid was obtained, that the 
 amount of its biliary ingredients was not ascertained. It reacted 
 perfectly, however, with Pettenkofer's test, showing that bile was 
 really present. 
 
 Time after 
 
 Quautity of fluid 
 
 Dry residue 
 
 Quantity of 
 
 Proportion of 
 
 feeding. 
 
 iu l.i minutes. 
 
 of same. 
 
 biliary matters. 
 
 biliary matters 
 to dry residue. 
 
 Immediately 
 
 640 grains 
 
 33 grains 
 
 10 grains 
 
 .30 
 
 1 hour 
 
 1,990 " 
 
 105 " 
 
 4 " 
 
 .03 
 
 3 hours 
 
 780 " 
 
 60 " 
 
 4 " 
 
 .07 
 
 6 " 
 
 750 " 
 
 73 " 
 
 H " 
 
 .05 
 
 9 " 
 
 860 " 
 
 78 " 
 
 4i " 
 
 .06 
 
 12 " 
 
 325 " 
 
 23 " 
 
 3f " 
 
 .16 
 
 15 " 
 
 347 " 
 
 18 " 
 
 4 " 
 
 .22 
 
 18 " 
 
 
 
 
 
 
 
 
 
 . 21 « 
 
 384 " 
 
 11 " 
 
 1 '• 
 
 .09 
 
 24 " 
 
 163 " 
 
 H " 
 
 3i " 
 
 .34 
 
 25 " 
 
 151 " 
 
 5 " 
 
 3 " 
 
 .60 
 
 From this it appears that the bile passes into the intestine in by 
 far the largest quantity immediately after feeding, and within the 
 first hour. After that time its discharge remains pretty constant ; 
 not varying much from four grains of solid biliary matters every 
 fifteen minutes, or sixteen grains per hour. The animal used for 
 the above observations weighed thirty-six and a half pounds. 
 
158 THE BILE. 
 
 The next point to be ascertained with regard to this question is 
 the following, viz : What hecomes of the bile in its passage through 
 the intestine? Our experiments, performed with a view of settling 
 this point, were tried on dogs. The animals were fed with fresh 
 meat, and then killed at various intervals after the meals, the abdo- 
 men opened, ligatures placed upon the intestine at various points, 
 and the contents of its upper, middle, and lower portions collected 
 and examined separately. The results thus obtained show that, 
 under ordinary circumstances, the bile, which is quite abundant in 
 the duodenum and upper part of the small intestine, diminishes in 
 quantity from above downward, and is not to be found in the large 
 intestine. The entire quantity of the intestinal contents also dimi- 
 nishes, and their consistency increases, as we approach the ileo- 
 caecal valve; and at the same time their color changes from a light 
 yellow to a dark bronze or blackish-green, which is always strongly 
 pronounced in the last quarter of the small intestine. 
 
 The contents of the small and large intestine were furthermore 
 evaporated to dryness, extracted with absolute alcohol, and the 
 alcoholic solutions precipitated with ether ; the quantity of ether 
 precipitate being regarded as representing approximatively that of 
 the biliary substances proper. The result showed that the quantity 
 of this ether precipitate is, both positively and relatively, very much 
 less in the large intestine than in the small. Its proportion to the 
 entire solid contents, is only one-fifth or one-sixth as great in the 
 large intestine as it is in the small. But even this inconsiderable 
 quantity, found in the contents of the large intestine, does not con- 
 sist of biliary matters ; for the watery solutions being treated with 
 sugar and sulphuric acid, those from both the upper and lower 
 portions of the small intestine always gave Pettenkofer's reaction 
 promptly and perfectly in less than a minute and a half; while in 
 that from the large intestine no red or purple color was produced, 
 even at the end of three hours. 
 
 The small intestine consequently contains, at all times, substances 
 giving all the reactions of the biliary ingredients; while in the 
 contents of the large intestine no such substances can be recognized 
 by Pettenkofer's test. 
 
 The biliary matters, therefore, disappear in their passage through 
 the intestine. 
 
 In endeavoring to ascertain what is the precise /M?-/c^?■o?^ of the Ule 
 in the intestine, our first object must be to determine what part, if 
 
VAKIATIONS AND FUNCTIONS OF BILE. 159 
 
 any, it takes in tlie digestive process. As the liver is situated, like 
 the salivary glands and the pancreas, in the immediate vicinity of 
 the alimentary canal, and like them, discharges its secretion into 
 the cavity of the intestine, it seems at first natural to regard the 
 bile as one of the digestive fluids. We have previously shown, 
 however, that the digestion of all the different elements of the food 
 is provided for by other secretions ; and furthermore, if we examine 
 experimentally the digestive power of bile on alimentary substances, 
 we obtain only a negative result. Bile exerts no special action upon 
 either albuminoid, starchy, or oleaginous matters, when mixed with 
 them in test-tubes and kept at the temperature of 100° F. It has 
 therefore, apparently, no direct influence in the digestion of these 
 substances. 
 
 Furthermore it appears, from the experiments detailed above, 
 that the secretion of the bile and its discharge into the intestine 
 are not confined to the periods of digestion, but take place con- 
 stantly, and continue even after the animal has been kept for many 
 days without food. These facts would lead us to regard the bile as 
 simply an excrementitious fluid ; containing only ingredients resulting 
 from the waste and disintegration of the animal tissues, and not 
 intended to perform any particular function, digestive or otherwise, 
 but merely to be eliminated from the blood, and discharged from 
 the system. The same view is more or less supported, also, by the 
 following facts, viz: — 
 
 1st. The bile is produced, unlike all the other animal secretions, 
 from venous blood ; that is, the blood of the portal vein, which has 
 already become contaminated by circulation through the abdominal 
 organs, and may be supposed to contain disorganized and effete 
 ingredients ; and 
 
 2d. Its complete suppression produces, in the human subject, 
 symptoms of poisoning of the nervous system, analogous to those 
 which follow the suppression of the urine, or the stoppage of respi- 
 ration, and the patient dies, usually in a comatose condition, at the 
 end of ten or twelve days. 
 
 The above circumstances, taken together, would combine to 
 make it appear that the bile is simply an excrementitious fluid, not 
 necessary or useful as a secretion, but only destined, like the urine, 
 to be eliminated and discharged. Nevertheless experiment has 
 shown that such is not the case ; and that, in point of fact, it is 
 necessary for the life of the animal, not only that the bile be secreted 
 and discharged, but furthermore that it be discharged into the 
 
160 THE JBILE. 
 
 intestine, and pass through the tract of the alimentary canal. The 
 most satisfactory experiments of this kind are those of Bidder and 
 Schmidt,^ in which they tied the common biliary duct in dogs, and 
 then established a permanent fistula in the fundus of the gall-bladder 
 through which the bile was allowed to flow by a free external orifice. 
 In this manner the bile was effectually excluded from the. intestine, 
 but at the same time was freely and wholly discharged from the 
 body, by the artificial fistula. If the bile therefore were simply an 
 excrementitious fluid, its deleterious ingredients being all eliminated 
 as usual, the animals would not suffer any serious injury from this 
 operation. If, on the contrary, they were found to suffer or die in 
 consequence of it, it would show that the bile has really some im- 
 portant function to perform in the intestinal canal, and is not simply 
 excrementitious in its nature. 
 
 The result showed that the effects of such an experiment were 
 fatal to the animal. Four dogs only survived the immediate effects 
 of the operation, and were afterward frequently used for purposes 
 of experiment. One of them was an animal from which the spleen 
 had been previously removed, and whose appetite, as usual after 
 this operation, was morbidly ravenous; his sj^stem, accordingly, 
 being placed under such unnatural conditions as to make him an 
 unfit subject for further experiment. In the second animal that 
 survived, the communication of the biliary duct with the intestine 
 became re-established after eighteen days, and the experiment con- 
 sequently had no result. In the remaining two animals, however, 
 everything was successful. The fistula in the gall-bladder became 
 permanently established ; and the bile-duct, as was proved subse- 
 quently by post-mortem examination, remained completely closed, 
 so that no bile found its way into the intestine. Both these ani- 
 mals died; one of them at the end of twenty-seven days, the other 
 at the end of thirty-six days. In both, the symptoms were nearly 
 the same, viz., constant and progressive emaciation, which proceeded 
 to such a degree that nearly every trace of fat disappeared from the 
 body. The loss of flesh amounted, in one case to more than two- 
 fifths, and in the other to nearly one-half the entire weight of the 
 animal. There was also a falling off of the hair, and an unusually 
 disagreeable, putrescent odor in the feces and in the breath. Not- 
 withstanding this, the appetite, remained good. Digestion was not 
 essentially interfered with, and none of the food was discharged 
 
 ' Op. cit., p. 103. 
 
VAEIATIONS AND FUNCTIONS OF BILE. 161 
 
 with the feces ; but there was much rumbling and gurgling in the 
 intestines, and abundant discharge of flatus, more strongly marked 
 in one instance than in the other. There was no pain ; and death 
 took place, at last, without any violent symptoms, but by a simple 
 and gradual failure of the vital powers. 
 
 How is it, then, that although the bile be not an active agent in 
 digestion, its presence in the alimentary canal is still essential to 
 life ? What office does it perform there, and how is it finally dis- 
 posed of? 
 
 We have already shown that the bile disappears in its passage 
 through the intestine. This disappearance may be explained in 
 two different ways. First, the biliary matters may be actually re- 
 absorbed from the intestine, and taken up by the bloodvessels ; or 
 secondly, they may be so altered and decomposed by the intestinal 
 fluids as to lose the power of giving Pettenkofer's reaction with 
 sugar and sulphuric acid, and so pass off with the feces in an 
 insoluble form. Bidder and Schmidt' have finally determined this 
 point in a satisfactory manner ; and have demonstrated that the 
 biliary substances are actually reabsorbed, by showing that the 
 quantity of sulphur present in the feces is far inferior to that 
 contained in the biliary ingredients as they are discharged into the 
 intestine. 
 
 These observers collected and analyzed all the feces passed, dur- 
 ing five days, by a healthy'dog, weighing 17.7 pounds. The entire 
 fecal mass during this period weighed 1508.15 grains, 
 
 ( Water 874.20 grains. 
 
 Containing I g^^.^^,^^.^^^ g33_g5 , 
 
 1508.15 
 
 The solid residue was composed as follows: — 
 
 Neutral fat, soluble in ether . . 43.710 grains. 
 
 Fat, witli traces of biliary matter . 77.035 " 
 
 Alcohol extract with biliary matter 58.900 containing 1.085 grs. of sulphur. 
 
 Substances not of a biliary nature 
 
 extracted by muriatic acid and 
 
 hot alcohol .... 148.800 containing 1.302 grs. of sulphur. 
 
 2.387 
 Fatty acids with oxide of iron . 98.425 
 Residue consisting of hair, sand, &c., 207.080 
 
 633.950 
 
 ' Op. cit., p. 217. 
 11 
 
162 THE BILE. 
 
 Now, as it lias already been shown that the dog secretes, during 
 24 hours, 6.916 grains of solid biliary matter for every pound weight 
 of the whole body, the entire quantity of biliary matter secreted 
 in five days by the above animal, weighing 17.7 pounds, must have 
 been 612.5 grains, or nearly as much as the whole weight of the 
 dried feces. But furthermore, the natural proportion of sulphur 
 in dog's bile (derived from the uncrystallizable biliary matter), is six 
 per cent, of the dry residue. The 612.5 grains of dry bile, secreted 
 during five days, contained therefore 86.75 grains of sulphur. 
 But the entire quantity of sulphur, existing in any form in the 
 feces, was 5.952 grains ; and of this only 2.387 grains were derived 
 from substances which could have been the products of biliary 
 matters — the remainder being derived from the hairs which are 
 always contained in abundance in the feces of the dog. That is, 
 not more than one-fifteenth part of the sulphur, originally present 
 in the bile, could be detected in the feces. As this is a simple 
 chemical element, not decomposable by any known means, it must, 
 accordingly, have been reabsorbed from the intestine. 
 
 We have endeavored to complete the evidence thus furnished by 
 Bidder and Schmidt, and to demonstrate directly the reabsorption 
 of the biliary matters, by searching for them in the ingredients of 
 the portal blood. AVe have examined, for this purpose, the portal 
 blood of dogs, killed at various periods after feeding. The animals 
 were killed by section of the medulla oblongata, a ligature imme- 
 diately placed on the portal vein, while the circulation was still 
 active, and the requisite quantity of blood collected by opening 
 the vein. The blood was sometimes immediately evaporated to 
 dryness by the water bath. Sometimes it was coagulated by boil- 
 ing in a porcelain capsule, over a spirit lamp, with water and an 
 excess of sulphate of soda, and the filtered watery solution after- 
 ward examined. But most frequently the blood, after being col- 
 lected from the vein, was coagulated by the gradual addition of 
 three times its volume of alcohol at ninety-five per cent., stirring 
 the mixture constantly, so as to make the coagulation gradual and 
 uniform. It was then filtered, the moist mass remaining on the filter 
 subjected to strong pressure in a linen bag, by a porcelain press, 
 and the fluid thus obtained added to that previously filtered. The 
 entire spirituous solution was then evaporated to dryness, the dry 
 residue extracted with absolute alcohol, and the alcoholic solution 
 treated as usual, with ether, &c., to discover the presence of biliary 
 matters. In every instance, blood was taken at the same time from 
 
VARIATIONS AND FUNCTIONS OF BILE. 163 
 
 the jugular, or tlie abdominal vena cava, and treated in the same 
 way for purposes of comparison. 
 
 "We have examined the blood, in this way, one, four, six, nine, 
 eleven and a half, twelve, and twenty hours after feeding. As the 
 result of these examinations, we have found that in the venous blood, 
 both of the portal vein and of the general circulation, there exists 
 a substance soluble in water and absolute alcohol, and precipitable 
 by ether from its alcoholic solution. This substance is often consi- 
 derably more abundant in the portal blood than in that taken from 
 the general venous system. It adheres closely to the sides of the 
 glass after precipitation, so that it is always difficult, and often im- 
 possible, to obtain enough of it, mixed with ether, for microscopic 
 examination. It dissolves, also, like the biliary substances, with 
 great readiness in water ; but in no instance have we ever been able 
 to obtain from it such a satisfactory reaction with Pettenkofer's test, 
 as would indicate the presence of bile. This is not because the 
 reaction is masked, as might be suspected, by some of the other 
 ingredients of the blood ; for if at the same time, two drops of bile 
 be added to half an ounce of blood taken from the abdominal vena 
 cava, and the two specimens treated alike, the ether precipitate may 
 be considerably more abundant in the case of the portal blood ; and 
 yet that from the blood of the vena cava, dissolved in water, will 
 give Pettenkofer's reaction for bile perfectly, while that of the por- 
 tal blood will give no such reaction. 
 
 Notwithstanding, then, the irresistible evidence afforded by the 
 experiments of Bidder and Schmidt, that the biliary matters are 
 really taken up by the portal blood, we have failed to recognize 
 them there by Pettenkofer's test. They must accordingly undergo 
 certain alterations in the intestine, previously to their absorption, so 
 that they no longer give the ordinary reaction of the biliary sub- 
 stances. We cannot say, at present, precisely what these alterations 
 are ; but they are evidently transformations of a catalytic nature, 
 produced by the contact of the bile with the intestinal juices. 
 
 The bile, therefore, is a secretion which has not yet accomplished 
 its function when it is discharged from the liver and poured into the 
 intestine. On the contrary, during its passage through the intestine 
 it is still in the interior of the body, in contact with glandular sur- 
 faces, and mingled with various organic substances, the ingredients 
 of the intestinal fluids, which act upon it as catalytic bodies, and 
 produce in it new transformations. This may account for the fact 
 stated above, that the bile, though a constant and uninterrupted 
 
164 THE BILE. 
 
 secretion, is nevertheless poured into the intestine in the greatest 
 abundance immediately after a hearty meal. This is not because it 
 is to take any direct part in the digestion of the food ; but because 
 the intestinal fluids, being themselves present at that time in the 
 greatest abundance, can then act upon and decompose the greatest 
 quantity of bile. At all events, the biliary ingredients, after being 
 altered and transformed in the intestine, as they might be in the 
 interior of a glandular organ, re-enter the blood under some new 
 form, and are carried away by the circulation, to complete their 
 function in some other part of the body. 
 
FOKMATION OF SUGAR IN THE LIVER. 165 
 
 CHAPTER IX. 
 
 FORMATION OF SUGAR IN THE LIVER. 
 
 Beside the secretion of bile, the liver performs also another 
 exceedingly important function, viz., the -produclion of sugar by a 
 metamorphosis of some of its organic ingredients. 
 
 Under ordinary circumstances a considerable quantity of sac- 
 charine matter is introduced with the food, or produced, from 
 starchy substances, by the digestive process in the intestinal canal. 
 In man and the herbivorous animals, accordingly, an abundant * 
 supply of sugar is derived from these sources ; and, as we have 
 already shown, the sugar thus introduced is necessary for the proper 
 support of the vital functions. For though the saccharine matter 
 absorbed from the intestine is destroyed by decomposition soon 
 after entering the circulation, yet the chemical changes by which 
 its decomposition is eifected are themselves necessary for the proper 
 constitution of the blood, and the healthy nutrition of the tissues. 
 Experiment shows, however, that the system does not depend, for • 
 its supply of sugar, entirely upon external sources ; but that sac- 
 charine matter is also produced independently, in the tissue of the 
 liver, whatever may be the nature of the food upon which the 
 animal subsists. 
 
 This important function was first discovered by M. Claude 
 Bernard' in 1848, and described by him under the name of the 
 glycogenic function of the liver. 
 
 It has long been known that sugar may be abundantly secreted, 
 under some circumstances, when no vegetable matters have been 
 taken with the food. The milk, for example, of all animals, car- 
 nivorous as Avell as herbivorous, contains a notable proportion of 
 sugar ; and the quantity thus secreted, during lactation, is in some 
 instances very great. In the human subject, also, when suffering 
 from diabetes, the amount of saccharine matter discharged with the 
 
 ' Nouvelle Fonction du Foie. Paris, 1853. 
 
166 FORMATION OF SUGAR IN THE LIVER. 
 
 urine has often appeared to be altogether out of proportion to that 
 which could be accounted for by the vegetable substances taken as 
 food. The experiments of Bernard, the most important of which 
 we have repeatedly confirmed, in common with other investigators, 
 show that in these instances most of the sugar has an internal 
 origin, and that it first makes its appearance in the tissue of the 
 liver. 
 
 If a carnivorous animal, as, for example, a dog or a cat, be fed 
 for several days exclusively upon meat, and then killed, the liver 
 alone of all the internal organs is found to contain sugar among its 
 other ingredients. For this purpose, a portion of the organ should 
 be cut into small pieces, reduced to a pulp by grinding in a mortar 
 with a little water, and the mixture coagulated by boiling with an 
 excess of sulphate of soda, in order to precipitate the albuminous 
 and coloring matters. The filtered fluid will then reduce the oxide 
 of copper, with great readiness, on the application of Trommer's 
 test. A decoction of the same tissue, mixed with a little yeast, will 
 also give rise to fermentation, producing alcohol and carbonic acid, 
 as is usual with saccharine solutions. On the contrary, the tissues 
 of the spleen, the kidneys, the lungs, the muscles, &c,, treated in the 
 same way, give no indication of sugar, and do not reduce the salts 
 of copper. Every otlier organ in the body may be entirely desti- 
 tute of sugar, but the liver always contains it in considerable quan- 
 tity, provided the animal be healthy. Even the blood of the portal 
 vein, examined by a similar process, contains no saccharine element, 
 and yet the tissue of the organ supplied by it shows an abundance 
 of saccharine ingredients. 
 
 It is remarkable for how long a time the liver will continue to 
 exhibit the presence of sugar, after all external supplies of this 
 substance have been cut off. Bernard kept two dogs under his own 
 observation, one for a period of three, the other of eight months,^ 
 during which period they were confined strictly to a diet of animal 
 food (boiled calves' heads and tripe), and then killed. Upon ex- 
 amination, the liver was found, in each instance, to contain a 
 proportion of sugar fully equal to that present in the organ under 
 ordinary circumstances. 
 
 The sugar, therefore, which is found in the liver after death, is a 
 normal ingredient of the hepatic tissue. It is not formed in other 
 parts of the body, nor absorbed from the intestinal canal, but takes 
 
 ' Nouvelle Fonction du Foie, p. 50. 
 
FORMATION OF SUGAR IN THE LIVER. 167 
 
 its origin in the liver itself; it is produced, as a new formation, 
 by a secreting process in the tissue of the organ. 
 
 The presence of sugar in the liver is common to all species of 
 animals, so far as is yet known. Bernard found it invariably in 
 monkeys, dogs, cats, rabbits, the horse, the ox, the goat, the sheep, 
 in birds, in reptiles, and in most kinds of fish. It was only in two 
 species of fish, viz., the eel and the ray (Murasna angnilla and Raia 
 batis), that he sometimes failed to discover it; but the failure in 
 these instances was apparently owing to the commencing putres- 
 cence of the tissue, by which the sugar had probably been destroyed. 
 In the fresh liver of the human subject, examined after death from 
 accidental violence, sugar was found to be present in the proportion 
 of 1.10 to 2.14 per cent, of the entire weight of the organ. 
 
 The following list shows the average percentage of sugar present 
 in the healthy liver of man and different species of animals, accord- 
 ing to the examinations of Bernard : — 
 
 Pekcentage of Sugar in the Liver. « 
 
 In man .... 1.68 In ox . . . . 2.30 
 
 " monkey 
 " dog . 
 " cat 
 " rabbit 
 " sheep 
 
 2.15 " horse .... 4.08 
 
 1.69 " goat .... 3.89 
 
 1.94 " birds .... 1.49 
 
 1.94 " reptiles . . . 1.04 
 
 2.00 " fish . . . . 1.45 
 
 With regard to the nature and properties of the liver sugar, it 
 resembles very closely glucose, or the sugar of starch, the sugar of 
 honey, and the sugar of milk, though it is not absolutely identical 
 with either one of them. Its solution reduces, as we have seen, the 
 salts of copper in Trommer's test, and becomes colored brown when 
 boiled with caustic potass. It ferments very readily, also, when 
 mixed witb yeast and kept at the temperature of 70° to 100° F. 
 It is distinguished from all the other sugars, according to Bernard,^ 
 by the readiness with which it becomes decomposed in the blood — 
 since cane sugar and beet root sugar, if injected into the circulation 
 of a living animal, pass through the system without sensible decom- 
 position, and are discharged unchanged with the urine ; sugar of 
 milk and glucose, if injected in moderate quantity, are decomposed 
 in the blood, but if introduced in greater abundance make their 
 appearance also in the urine ; while a solution of liver sugar, though 
 injected in much larger quantity than either of the others, may dis- 
 
 ' Lemons de Physiologic Experimentale. Paris, 1855, p. 213. 
 
168 rORMATIOX OF SUGAR IN THE LIVER. 
 
 appear altogether in the circulation, without passing off' by the 
 kidneys. 
 
 This substance is therefore a sugar of animal origin, similar in 
 its properties to other varieties of saccharine matter, derived from 
 different sources. 
 
 The sugar of the liver is not produced in the blood by a direct 
 decomposition of the elements of the circulating fluid in the vessels 
 of the organ, but takes its origin in the solid substance of the hepatic 
 tissue^ as a natural ingredient of its organic texture. The blood 
 which may be pressed out from a liver recently extracted from the 
 body, it is true, contains sugar ; but this sugar it has absorbed from 
 the tissues of the organ in which it circulates. This is demonstrated 
 by the singular fact that the fresh liver of a recently killed animal, 
 though it may be entirely drained of blood and of the sugar which 
 it contained at the moment of death, will still continue for a certain 
 time to produce a saccharine substance. If such a liver be injected 
 with water by the portal vein, and all the blood contained in its 
 vessels washed out by the stream, the water which escapes by the 
 hepatic vein will still be found to contain sugar. M. Bernard has 
 found' that if all the sugar contained in a fresh liver be extracted in 
 this manner by a prolonged watery injection, so that neither the 
 water which escapes by the hepatic vein, nor the substance of the 
 liver itself, contain any further traces of sugar, and if the organ be 
 then laid aside for twenty-four hours, both the tissue of the liver and 
 the fluid which exudes from it will be found at the end of that time 
 to have again become highly saccharine. The sugar, therefore, is 
 evidently not produced in the blood circulating through the liver, 
 but in the substance of the organ itself. Once having originated 
 in the hepatic tissue, it is absorbed thence by the blood, and trans- 
 ported by the circulation, as we shall hereafter show, to other parts 
 of the body. 
 
 The sugar which thus originates in the tissue of the liver, is pro- 
 duced by a mutual decomposition and transformation of various 
 other ingredients of the hepatic substance ; these chemical changes 
 being a part of the nutritive processes by which the tissue of the 
 organ is constantly sustained and nourished. There is probably a 
 series of several different transformations which take place in this 
 manner, the details of which are not yet known to us. It has been 
 discovered, however, that one change at least precedes the final 
 
 ' Gazette Hebdomadaire, Paris, Oct. 5, 1855. 
 
FORMATION OF SUGAR IN THE LIVER. 169 
 
 production of saccharine matter ; and that the sugar itself is pro- 
 duced by the transformation of another peculiar substance, of ante- 
 rior formation. This substance, which precedes the formation of 
 sugar, and which is itself produced in the tissue of the liver, is 
 known by the name of the glycogenic matter^ or glycogene. 
 
 This glj^cogenic matter may be extracted from the liver in the 
 following manner. The organ is taken immediately from the body 
 of the recently killed animal, cut into small pieces, and coagulated by 
 being placed for a few minutes in boiling water. This is in order 
 to prevent the albuminous liquids of the organ from acting upon 
 the glj'cogenic matter and decomposing it at a medium temperature. 
 The coagulated tissue is then drained, placed in a mortar, reduced 
 to a pulp by bruising and grinding, and afterward boiled in dis- 
 tilled water for a quarter of an hour or more, by which the glyco- 
 genic matter is extracted and held in solution by the boiling water. 
 
 The liquid of decoction, which should be as concentrated as pos- 
 sible, must then be expressed, strained, and filtered, after which it 
 appears as a strongly opalescent fluid, of a slightly yellowish tinge. 
 The glycogenic matter which is held in solution may be precipi- 
 tated by the addition to the filtered fluid of five times its volume of 
 alcohol. The precipitate, after being repeatedly washed with 
 alcohol in order to remove sugar and biliary matters, may then be 
 redissolved in distilled water. It may be precipitated from its 
 watery solution either by alcohol in excess or by crystallizable 
 acetic acid, in both of which it is entirely insoluble, and mav be 
 afterward kept in the dry state for an indefinite time without losing 
 its properties. 
 
 The glycogenic matter, obtained in this way, is regarded as 
 intermediate in its nature and properties between hydrated starch 
 and dextrine. Its ultimate composition, according to M. Pelouze," 
 is as follows : — 
 
 When brought into contact with iodine, it produces a coloration 
 varying from violet to a deep, clear, maroon red. It does not 
 reduce the salts of copper in Troramer's test, nor does it ferment 
 when placed in contact with yeast at the proper temperature. It 
 does not, therefore, of itself contain sugar. It may easily be con- 
 verted into sugar, however, by contact with any of the animal 
 ferments, as, for example, those contained in the saliva or in the 
 
 ' Journal de Physiologie, Paris, 1858, p. 552. 
 
170 FORMATION OF SUGAR IN" THE LIVER. 
 
 blood. If a solution of glycogenic matter be mixed witb fresli 
 human saliva, and kept for a few minutes at the temperature of 
 100° F., the mixture will then be found to have acquired the power 
 of reducing the salts of copper and of entering into fermentation by 
 contact with yeast. The glycogenic matter has therefore been 
 converted into sugar by a process of catalysis, in the same manner 
 as vegetable starch would be transformed under similar conditions. 
 
 The glycogenic matter which is thus destined to be converted 
 into sugar, is formed in the liver by the processes of nutrition. It 
 may be extracted, as we have seen above, from the hepatic tissue 
 of carnivorous animals, and is equally present when they have been 
 exclusively confined for many days to a meat diet. It is not in- 
 troduced with the food ; for the fleshy meat of the herbivora does 
 not contain it in appreciable quantity, though these animals so 
 constantly take starchy substances with their food. In them, the 
 starchy matters are transformed into sugar by digestion, and the 
 sugar so produced is rapidly destroyed after entering the circula- 
 tion ; so that usually neither saccharine nor starchy substances are 
 to be discovered in the muscular tissue. M. Poggiale' found that 
 in very many experiments, performed by a commission of the 
 French Academy for the purpose of examining this subject, glyco- 
 genic matter was detected in ordinary butcher's meat only once. 
 We have also found it to be absent from the fresh meat of the 
 bullock's heart, when examined in the manner described above, 
 l^evertheless, in dogs fed exclusively upon this food for eight days, 
 glycogenic matter may be found in abundance in the liver, while 
 it does not exist in other parts of the body, as the spleen, kidney, 
 lungs, &c. 
 
 Furthermore, in a dog fed exclusively for eight days upon the 
 fresh meat of the bullock's heart, and then killed four hours after 
 a meal of the same food, at which time intestinal absorption is 
 going on in full vigor, the liver contains, as above mentioned, both 
 glycogenic matter and sugar; but neither sugar nor glycogenic mat- 
 ter can be found in the blood of the portal vein, when subjected to 
 a similar examination. 
 
 The glycogenic matter, accordingly, does not originate from any 
 external source, but is formed in the tissue of the liver ; where it 
 is soon afterward transformed into, sugar, while still forming a part 
 of the substance of the organ. 
 
 ' Journal de Pbysiologie, Paris, 1858, p. 558. 
 
FOEMATION OF SUGAE IN THE LIVER. 171 
 
 The formation of sugar in the liver is therefore a function com- 
 posed of two distinct and successive processes, viz : first, the forma- 
 tion, in the hepatic tissue, of a glycogenic matter, having some 
 resemblance to dextrine ; and secondly, the conversion of this gly- 
 cogenic matter into sugar, by a process of catalysis and transforma- 
 tion. 
 
 The sugar thus produced in the substance of the liver is absorbed 
 from it by the blood circulating in its vessels. The mechanism of 
 this absorption is probably the same with that which goes on in 
 other parts of the circulation. It is a process of transudation and 
 endosmosis, by which the blood in the vessels takes up the saccha- 
 rine fluids of the liver, during its passage through the organ. 
 While the blood of the portal vein, .therefore, in an animal fed 
 exclusively upon meat, contains no sugar, the blood of the hepatic 
 vein, as it passes upward to the heart, is always rich in saccharine 
 ingredients. This difference can easily be demonstrated by exa- 
 mining comparatively the two kinds of blood, portal and heptic, 
 from the recently killed animal. The blood in its passage through 
 the liver is found to have acquired a new ingredient, and shows, 
 upon examination, all the properties of a saccharine liquid. 
 
 The sugar produced in the liver is accordingly to be regarded as 
 a true secretion, formed by the glandular tissue of the organ, by a 
 similar process to that of other glandular secretions. It differs 
 from the latter, not in tbe manner of its production, but only in 
 the mode of its discharge. For while the biliary matters produced 
 in the liver are absorbed by the hepatic ducts and conducted down- 
 ward to the gall-bladder and the intestine, the sugar is absorbed by 
 the bloodvessels of the organ and carried upward, by the hepatic 
 veins, toward the heart and the general circulation. 
 
 The production of sugar in the liver during health is a constant 
 process, continuing, in many cases, for several days after the animal 
 has been altogether deprived of food. Its activity, howev&r, like 
 that of most other secretions, is subject to periodical augmentation 
 and diminution. Under ordinary circumstances, the sugar, which 
 is absorbed by the blood from the tissue of the liver, disappears 
 very soon after entering the circulation. As the bile is transformed 
 in the intestine, so the sugar is decomposed in the blood. We are 
 not yet acquainted, however, with the precise nature of the changes 
 which it undergoes after entering the vascular system. It is very 
 probable, according to the views of Lehmann and Robin, that it is 
 at first converted into lactic acid (CgHgOg), which decomposes in 
 
172 FORMATION OF SUGAR IN THE LIVER. 
 
 turn the alkaline carbonates, setting free carbonic acid, and form 
 ing lactates of soda and potass. But whatever be the exact mode 
 of its transformation, it is certain that the sugar disappears rapidly; 
 and while it exists in considerable quantity in the liver and in the 
 blood of the hepatic veins and the right side of the heart, it is not 
 usually to be found in the pulmonary veins nor in the blood of the 
 general circulation. 
 
 About two and a half or three hours, however, after the inges- 
 tion of food, according to the investigations of Bernard, the circu- 
 lation of blood through the portal system and the liver becomes 
 considerably accelerated. A larger quantity of sugar is then pro- 
 duced in the liver and carried away from the organ by the hepatic 
 veins ; so that a portion of it then escapes decomposition while 
 passing through the lungs, and begins to appear in the blood of 
 the arterial system. Soon afterward it appears also in the blood 
 of the capillaries ; and from four to six hours after the commence- 
 ment of digestion it is produced in the liver so much more rapidly 
 than it is destroyed in the blood, that the surplus quantity circulates 
 throughout the body, and the blood everywhere has a slightly 
 saccharine character. It does not, however, in the healthy condi- 
 tion, make its appearance in any of the secretions. 
 
 After the sixth hour, this unusual activity of the sugar producing 
 function begins again to diminish ; and the transformation of the 
 sugar in the circulation going on as before, it gradually disappears 
 as an ingredient of the blood. Finally, the ordinary equilibrium 
 between its production and its decomposition is re-established, and 
 it can no longer be found except in the liver and in that part of 
 the circulatory system which is between the liver and the lungs. 
 There is, therefore, a periodical increase in the amount of unde- 
 composed sugar in the blood, as we have already shown to be the 
 case with the fatty matter absorbed during digestion ; but this in- 
 crease is soon followed by a corresponding diminution, and during 
 the greater portion of the time its decomposition keeps pace with 
 its production, and it is consequently prevented from appearing in 
 the blood of the general circulation. 
 
 There are produced, accordingly, in the liver, two different secre- 
 tions, viz., bile and sugar. Both of them originate by transforma- 
 tion of the ingredients of the hepatic tissue, from which they are 
 absorbed by two different sets of vessels. The bile is taken up by 
 the biliary ducts, and by them discharged into the intestine; while 
 the sugar is carried off by the hepatic veins, to be decomposed in the 
 circulation, and become subservient to the nutrition of the blood. 
 
THE SPLEEN. 173 
 
 CHAPTER X. 
 
 THE SPLEEN. 
 
 The spleen is an exceedingly vascular organ, situated in the 
 vicinity of the great pouch of the stomach and supplied abund- 
 antly by branches of the coeliac axis. Its veins, like those of the 
 digestive abdominal organs, form a part of the great portal system, 
 and conduct the blood which has passed through it to the liver, 
 before it mingles again with the general current of the circulation. 
 
 The spleen is covered on its exterior by an investing membrane 
 or capsule, which forms a protective sac, containing the soft pulp 
 of Avhich the greater part of the organ is composed. This capsule, 
 in the spleen of the ox, is thick, whitish and opaque, and is com- 
 posed to a great extent of yellow elastic tissue. It accordingly 
 possesses, in a high degree, the physical property of elasticity, and 
 may be widely stretched without laceration ; returning readily to 
 its original size as soon as the extending force is relaxed. 
 
 In the carnivorous animals, on the other hand, the capsule of 
 the spleen is thinner, and more colorless and transparent. It con- 
 tains here but very little elastic tissue, being composed mostly of 
 smooth, involuntary muscular fibres, connected in layers by a little 
 intervening areolar tissue. In the herbivorous animals, accordingly, 
 the capsule of the spleen is simply elastic, while in the carnivora it 
 is contractile. 
 
 In both instances, however, the elastic and contractile properties 
 of the capsule subserve a nearly similar purpose. There is every 
 reason to believe that the spleen is subject to occasional and per- 
 haps regular variations in size, owing to the varying condition of 
 the abdominal circulation. Dr. William Dobson^ found that the 
 size of the organ increased, from the third hour after feeding up to 
 the fifth ; when it arrived at its maximum, gradually, decreasing 
 after that period. When these periodical congestions take place, 
 
 ' In Gray, on tlie Structure and Uses of the Spleen. London, 1854, p. 40. 
 
174. THE SPLEEN. 
 
 the organ becoming turgid with blood, the capsule is distended ; 
 and limits, by its resisting power, the degree of tumefaction to 
 which the spleen is liable. When the disturbing cause has again 
 passed away, and the circulation is about to return to its ordinary 
 condition, the elasticity of the capsule in the herbivora and its con- 
 tractility in the carnivora, compress the soft vascular tissue within, 
 and reduce the organ to its original dimensions. This contractile 
 action of the investing capsule can be readily seen in the dog or 
 the cat, by opening the abdomen while digestion is going on, ex- 
 posing the spleen and removing it, after ligature of its vessels. 
 When first exposed, the organ is plump and rounded, and presents 
 externally a smooth and shining surface. But as soon as it has 
 been removed from the abdomen and its vessels divided, it begins 
 to contract sensibly, becomes reduced in size, stiffj and resisting to 
 the touch ; while its surface, at the same time, becomes uniformly 
 wrinkled, by the contraction of its muscular fibres. 
 
 In its interior, the substance of the spleen is traversed everywhere 
 by slender and ribbon-like cords of fibrous tissue, which radiate 
 from the sheath of its principal arterial trunks, and are finally 
 attached to the internal surface of its investing capsule. These 
 fibrous cords, or irabeculce, as they are called, by their frequent 
 branching and mutual interlacement, form a kind of skeleton or 
 framework by which the soft splenic pulp is embraced, and the 
 shape and integrity of the organ maintained. They are composed 
 of similar elements to those of the investing capsule, viz., elastic 
 tissue and involuntary muscular fibres, united with each other by 
 a varying quantity of the fibres of areolar tissue. 
 
 The interstices between the trabeculae of the spleen are occupied 
 by the splenic pulp; a soft, reddish substance, which contains, 
 beside a few nerves and lymphatics, capillary bloodvessels in great 
 profusion, and certain whitish globular bodies, which may be re- 
 garded as the distinguishing anatomical elements of the organ, and 
 which are termed the Malpighian bodies of the spleen. 
 
 The Malpighian bodies are very abundant, and are scattered 
 throughout the splenic pulp, being most frequently attached to the 
 sides, or at the point of bifurcation of some small artery. They 
 are readily visible to the naked eye in the spleen of the ox, upon a 
 fresh section^of the organ, as minute, whitish, rounded bodies, which 
 may be separated, by careful manipulation, from the surrounding 
 parts. In the carnivorous animals, on the other hand, and in the 
 human subject, it is more difficult to distinguish them by the un- 
 
THE SPLEEN. 176 
 
 aided eye, though they always exist in the spleen in a healthy 
 condition. Their average diameter, according to Kcilliker, is y^\ of 
 an inch. They consist of a closed sac, or capsule, containing in 
 its interior a viscid, semi-solid mass of cells, cell-nuclei, and homo- 
 geneous substance. Each Malpighian body is covered, on its exte- 
 rior, by a network of fine capillary bloodvessels; and it is now 
 perfectly well settled, by the observations of various anatomists 
 (Kcilliker, Busk, Huxley, &c.), that bloodvessels also penetrate into 
 the substance of the Malpighian body, and there form an internal 
 capillary plexus. 
 
 The spleen is accordingly a glandular organ, analogous in its 
 minute structure to the solitary and agminated glands of the small 
 intestine, and to the lymphatic glands throughout the body. Like 
 them, it is a gland without an excretory duct ; and resembles also, 
 in this respect, the thyroid and thymus glands and the supra-renal 
 capsules. All these organs have a structure which is evidently 
 glandular in its nature, and yet the name of glands has been some- 
 times refused to them because they have, as above mentioned, no 
 duct, and produce apparently no distinct secretion. We have 
 already seen, however, that a secretion may be produced in the 
 interior of a glandular organ, like the sugar in the substance of the 
 liver, and yet not be discharged by its excretory duct. The veins 
 of the gland, in this instance, perform the part of excretory ducts. 
 They absorb the new materials, and convey them, through the 
 medium of the blood, to other parts of the body, where they suffer 
 subsequent alterations, and are finally decomposed in the circula- 
 tion. 
 
 The action of such organs is consequently to modify the consti- 
 tution of the blood. As the blood passes through their tissue, it 
 absorbs from the glandular substance certain materials which it did 
 not previously contain, and which are necessary to the perfect con- 
 stitution of the circulating fluid. The blood, as it passes out from 
 the organ, has therefore a different composition from that which it 
 possessed before its entrance; and on this account the name of 
 vascular glands has been applied to all the glandular organs above 
 mentioned, which are destitute of excretory ducts, and is eminently 
 applicable to the spleen. 
 
 The precise alteration, however, which is effected in the blood 
 during its passage through the splenic tissue, has not yet been 
 discovered. Various hypotheses have been advanced from time to 
 time, as to the processes which go on in this organ ; many of them 
 
176 THE SPLEEIST. 
 
 vague and indefinite in character, and some of them directly con- 
 tradictory of each other. None, however, have yet been offered 
 which are entirely satisfactory in themselves, or which rest on suffi- 
 ciently reliable evidence. 
 
 A very remarkable fact with regard to the spleen is that it may 
 be entirely removed, in many of the lower animals, without its loss 
 producing any serious permanent injury. This experiment has 
 been frequently performed by various observers, and we have our- 
 selves repeated it several times with similar results. The organ 
 may be easily removed, in the dog or the cat, by drawing it out 
 of the abdomen, through an opening in the median line, placing a 
 few ligatures upon the vessels of the gastro-splenic omentum, and 
 then dividing the vessels between the ligatures and the spleen. The 
 wound usually heals without difficulty ; and if the animal be killed 
 some weeks afterward, the only remaining trace of the operation 
 is an adhesion of the omentum to the inner surface of the abdominal 
 parietes, at the situation of the original wound. 
 
 The most constant and permanent effect of a removal of the 
 spleen is an unusual increase of the appetite. This symptom we 
 have observed in some instances to be excessively developed ; so 
 that the animal would at all times throw himself, with an unnatural 
 avidity, upon any kind of food offered him. We have seen a dog, 
 subjected to this operation, afterward feed without hesitation upon 
 the flesh of other dogs; and even devour greedily the entrails, 
 taken warm from the abdomen of the recently killed animal. The 
 food taken in this unusual quantity is, however, perfectly well 
 digested ; and the animal will often gain very perceptibly in weight. 
 In one instance, a cat, in whom the unnatural appetite was marked 
 though not excessive, increased in weight from five to six pounds, 
 in the course of a little less than two months; and at the same 
 time the fur became sleek and glossy, and there was a considerable 
 improvement in the general appearance of the animal. 
 
 Another symptom, which usually follows removal of the spleen, 
 is an unnatural ferocity of disposition. The animal will frequently 
 attack others, of its own or a different species, without any appa- 
 rent cause, and without any regard to the difference of size, strength, 
 &c. This symptom is sometimes equally excessive with that of an 
 unnatural appetite ; while in other instances it shows itself only in 
 occasional outbursts of irritability and violence. 
 
 Neither of the symptoms, however, which we have just de- 
 scribed, appear to exert any permanently injurious effect upon the 
 
THE SPLEEN". 177 
 
 animal Avhich has been subjected to the operation; and life may be 
 prolonged for an indefinite period, without any serious disturbance 
 of the nutritive process, after the spleen has been completely 
 extirpated. 
 
 We must accordingly regard the spleen, not as a single organ, 
 but as associated with others, which may completely, or to a great 
 extent, perform its functions after its entire removal. We have 
 already noticed the similarity in structure between the spleen and 
 the mesenteric and lymphatic glands ; a similarity which has led 
 some writers to regard them as more or less closely associated with 
 each other in function, and to consider the spleen as an unusually 
 developed lymphatic or mesenteric gland. It is true that this 
 organ is provided with a comparatively scanty supply of lymphatic 
 vessels ; and the chyle, which is absorbed from the intestine, does 
 not pass through the spleen, as it passes through the remaining 
 mesenteric glands. Still, the physiological action of the spleen 
 may correspond with that of the other lymphatic glands, so far as 
 regards its influence on the blood; and there can be little doubt 
 that its function is shared, either by them or by some other glan- 
 dular organs, which become unnaturally active, and more or less 
 perfectly supply its place after its complete removal. 
 
 12 
 
178 THE BLOOD. 
 
 CHAPTER XI. 
 
 THE BLOOD. 
 
 The blood, as it exists in its natural condition, while circulating 
 in the vessels, is a thick opaque fluid, varying in color in different 
 parts of the body from a brilliant scarlet to a dark purple. It has 
 a slightly alkaline reaction, and a specific gravity of 1055. It 
 is not, however, an entirely homogeneous fluid, but is found on 
 microscopic examination to consist, first, of a nearly colorless, 
 transparent, alkaline fluid, termed the plasma, containing water, 
 fibrin, albumen, salts, &c., in a state of mutual solution; and, 
 secondly, of a large number of distinct cells, or corpuscles, the 
 blood- globules, swimming freely in the liquid plasma. These glo- 
 bules, which are so small as not to be distinguished by the naked 
 eye, by being mixed thus abundantly with the fluid plasma, give 
 to the entire mass of the blood an opaque appearance and a uni- 
 form red color. 
 
 BLOOD-GLOBULES. 
 
 On microscopic examination it is found that the globules of the 
 blood are of two kinds, viz., red and white ; of these the red are 
 by far the most abundant. 
 
 The o'ed globules of the blood present, under the microscope, a 
 perfectly circular outline and a smooth exterior. (B'ig. 54.) Their 
 size varies somewhat, in human blood, even in the same specimen. 
 The greater number of them have a transverse diameter of 3500 ^^ 
 an inch; but there are many smaller ones to be seen, which are 
 not more than gJ^o or even 4o'oo of ^^ ii^^h in diameter. Their 
 form is that of a spheroid, very much flattened on its opposite 
 surfaces, somewhat like a round biscuit, or a thick piece of money 
 with rounded edges. The blood-globule accordingly, when seen 
 flatwise, presents a comparatively broad surface and a circular out- 
 
BLOOD-GLOBULES. 
 
 179 
 
 Human Blood-globules. — a. Red globules, 
 seeu fiatwi-e. h. Red globules, seen edgewise, e. 
 White globule. 
 
 line (a); but if it be made to roll over, it will present itself edge- 
 wise during its rotation and assume the flattened form indicated 
 at h. The thickness of the 
 globule, seen in this position, 
 is about y 15^55 of an inch, or 
 a little less than one-fifth of 
 its transverse diameter. 
 
 When the globules are exa- 
 mined lying upon their broad 
 surfaces, it can be seen that 
 these surfaces are not exactly 
 flat, but that there is on each 
 side a slight central depres- 
 sion, so that the rounded 
 edges of the blood-globule 
 are evidently thicker than its 
 middle portion. This ine- 
 quality produces a remark- 
 able optical effect. The sub- 
 stance of which the blood-globule is composed refracts light more 
 strongly than the fluid plasma. Therefore, when examined with the 
 microscope, by transmitted light, the thick edges of the globules 
 act as double convex lenses, and concentrate the light above the 
 level of the fluid. Conse- 
 quently, if the object-glass be 
 carried upward by the ad- 
 justing screw of the micro- 
 scope, and lifted away from 
 tbe stage, so that the blood- 
 globules fall beyond its fo- 
 cus, their edges will appear 
 brighter. But the central por- 
 tion of each globule, being 
 excavated on both sides, acts 
 as a double concave lens, and 
 disperses the light from a 
 point below the level of the 
 fluid. It, therefore, grows 
 brighter as the object-glass 
 is carried downward, and the 
 object falls within its focus. 
 
 Red Globules op the Blood, 
 beyond the focus of the microscope. 
 
 seen a little 
 
 An alternating appearance of the 
 
180 
 
 THE BLOOD. 
 
 blood-globules may, therefore, be produced by viewing tliem first 
 beyond and then within the focus of the instrument. When be- 
 yond the focus, the globules will be seen with a bright rim and a 
 
 darlv centre. (Fig. 55.) When 
 within it, they will appear 
 with a dark rim and a bright 
 centre. (Fig. 56.) 
 
 The blood-globules accord- 
 ingly have the form of a 
 thickened disk with rounded 
 edges and a double central 
 excavation. They have, con- 
 sequently, been sometimes 
 called "blood-disks," instead 
 of blood-globules. The term 
 " disk," however, does not in- 
 dicate their exact shape, any 
 
 more than the other ; and 
 the term " blood-corpuscle," 
 which is also sometimes used, does not indicate it at all. And 
 although the term " blood-globule" may not be precisely a correct 
 one, still it is the most convenient ; and need not give rise to any 
 confusion, if we remember the real shape of the bodies designated 
 by it. This term will, consequently, be employed whenever we 
 have occasion to speak of the blood-globules in the following pages. 
 
 Within a minute after being 
 
 The same, seea a little withiu the focus. 
 
 Fig. 57. 
 
 Blood-globules 
 of coin. 
 
 adhering together, like rolls 
 
 placed under the microscope, 
 the blood-globules, after a 
 fluctuating movement of 
 short duration, very often 
 arrano;e themselves in slip;ht- 
 ly curved rows or chains, in 
 which they adhere to each 
 other by their flat surfaces, 
 presenting an appearance 
 which has been aptly com- 
 pared with that of rolls of 
 coin. This is probably owing 
 merely to the coagulation of 
 the blood, which takes place 
 very rapidly when it is spread 
 
BLOOD-GLOBULES. 181 
 
 out in thin layers and in contact with glass surfaces; and which, 
 by compressing the globules, forces them into such a position that 
 they may occupy the least possible space. This position is evi- 
 dently that in which they are applied to each other by their flat 
 surfaces, as above described. 
 
 The color of the blood-globules, when viewed by transmitted 
 light and spread out in a thin layer, is a light amber or pale yellow. 
 It is, on the contrary, deep red when they are seen by reflected 
 light, or piled together in comparatively thick layers. When viewed 
 singly, they are so transparent that the outlines of those lying under- 
 neath can be easily seen, showing through the substance of the 
 superjacent globules. Their consistency is peculiar. They are not 
 solid bodies, as they have been sometimes inadvertently described ; 
 but on the contrary have a consistency which is very nearly fluid. 
 They are in consequence exceedingly flexible, and easily elongated, 
 bent, or otherwise distorted by accidental pressure, or in passing 
 through the narrow currents of fluid which often establish them- 
 selves accidentally in a drop of blood under microscopic examina- 
 tion. This distortion, however, is only temporary, and the globules 
 regain their original shape, as soon as the accidental pressure is 
 taken off. The peculiar flexibility and elasticity thus noticed are 
 characteristic of the red globules of the blood, and may always 
 serve to distinguish them from any other free cells which may be 
 found in the animal tissues or fluids. 
 
 In structure the blood-globules are homogeneous. They have 
 been sometimes erroneously described as consisting of a closed 
 vesicle or cell-wall, containing in its cavity some fluid or serai-fluid 
 substance of a different character from that composing the wall of 
 the vesicle itself. No such structure, however, is really to be seen 
 in them. Each blood-globule consists of a mass of organized ani- 
 mal substance, perfectly or nearly homogeneous in appearance, and 
 of the same color, consistency and composition throughout. In 
 some of the lower animals (birds, reptiles, fish) it contains also 
 a granular nucleus, imbedded in the substance of the globule ; but 
 in no instance is there any distinction to be made out between an 
 external cell-wall and an internal cavity. 
 
 The appearance of the blood-globules is altered by the addition 
 of various foreign substances. If water be added, so as to dilute 
 the plasma, the globules absorb it by imbibition, swell, lose their 
 double central concavity and become paler. If a larger quantity 
 of water be added, they finally dissolve and disappear altogether. 
 
182 
 
 THE BLOOD. 
 
 B L D - G L O B U L E S , 
 
 water. 
 
 swollen by the imbibitiou of 
 
 When a moderate quantity of water is mixed with the blood, the 
 edges of the globules, being thicker than the central portions, 
 
 and absorbing water more 
 ^ig- 5S- abundantly, become turgid, 
 
 and encroach gradually upon 
 the central part. (Fig. 58.) 
 It is very common to see 
 the central depression, under 
 these circumstances, disap- 
 pear on one side before it 
 is lost on the other, so that 
 the globule, as it swells up, 
 curls over towards one side, 
 and assumes a peculiar cup- 
 shaped form (a). This form 
 may often be seen in blood- 
 globules that have been 
 soaking for some time in the 
 urine, or in any other animal 
 fluid of a less density than the plasma of the blood. Dilute acetic 
 acid dissolves the blood-globules more promptly than water, and 
 solutions of the caustic alkalies more promptly still. 
 
 If a drop of blood be allowed partially to evaporate while under 
 
 the microscope, the globules 
 Fig- 59. near the edges of the prepa- 
 
 ration often diminish in size, 
 and at the same time present 
 a shrunken and crenated ap- 
 pearance, as if minute gran- 
 ules were projecting from 
 their surfaces (Fig. 59); an 
 effect apparently produced 
 by the evaporation of part 
 of their watery ingredients. 
 For some unexplained rea- 
 son, however, a similar dis- 
 tortion is often produced in 
 some of the globules by the 
 addition of certain other ani- 
 mal fluids, as for example the 
 saliva; and a few can even be seen in this condition after the 
 addition of pure water. 
 
 Bloob-globdles 
 crenated. 
 
 shrunken, with their margins 
 
BLOOD-GLOBULES. 183 
 
 The entire mass of the blood-globules, in proportion to the rest 
 of the circulating fluid, can only be approximately measured by 
 the eve in a microscopic examination. In ordinary analyses the 
 globules are usually estimated as amounting to about fifteen per 
 cent., by weight, of the entire blood. This estimate, however, refers, 
 properly speaking, not to the globules themselves, but only to their 
 dry residue, after the water which they contain has been lost by 
 evaporation. It is easily seen, by examination with the microscope, 
 that the globules, in their natural semi-fluid condition, are really 
 much more abundant than this, and constitute fully one-half the 
 entire mass of the blood; that is, the intercellular fluid, or plasma, is 
 not more abundant than the globules themselves which are sus- 
 pended in it. When separated from the other ingredients of the 
 blood and examined by themselves, the globules are found, ac- 
 cording to Lehmann, to present the following composition : — 
 
 CoMPosiTiox OF THE Blocd-Globules IN 1000 Parts. 
 
 Water 688.00 
 
 Globnline ........... 282.22 
 
 Hsematine 16.75 
 
 Fatty substances ......... 2.31 
 
 Undetermined (extractive) matters . . . . . . 2.60 
 
 Chloride of sodium ....... 
 
 " potassium ...... 
 
 Phosphates of soda and potass ..... 
 
 Sulphates " " ...... 
 
 Phosphate of lime ....... 
 
 " magnesia . . . . . . 
 
 1- 8.12 
 
 1000.00 
 
 The most important of these ingredients is the glohuline. This 
 is an organic substance, nearly fluid in its natural condition by 
 union with water, and constituting the greater part of the mass of 
 the blood-globules. It is soluble in water, but insoluble in the 
 plasma of the blood, owing to the presence in that fluid of albumen 
 and saline matters. If the blood be largely diluted, however, the 
 globuline is dissolved, as already mentioned, and the blood-globules 
 are destroyed. Globuline coagulates by heat; but, according to 
 Eobin and Yerdeil, only becomes opalescent at 160°, and requires 
 for its complete coagulation a temperature of 200° F. 
 
 The hcematme is the coloring matter of the globules. It is, like 
 globuline, an organic substance, but is present in much smaller quan- 
 tity than the latter. It is not contained in the form of a powder, 
 mechanically deposited in the globuline, but the two substances are 
 
184 
 
 THE BLOOD. 
 
 intimately mingled throughout the mass of the blood-globule, just 
 as the fibrin and albumen are mingled in the plasma. Heematine 
 contains, like the other coloring matters, a small proportion of iron. 
 This iron has been supposed to exist under the form of an oxide ; 
 and to contribute directly in this way to the red color of the sub- 
 stance in question. But it is now ascertained that although the 
 iron is found in an oxidized form in the ashes of the blood-globules 
 after they have been destroyed by heat, its oxidation probably takes 
 place during the process of incineration. So far as we know, there- 
 fore, the iron exists originally in the h^ematine as an ultimate 
 element, directly combined with the other ingredients of this sub- 
 stance, in the same manner as the carbon, the hydrogen, or the 
 nitrogen. 
 
 The blood-globules of all the warm blooded quadrupeds, with 
 the exception of the family of the caraelidse, resemble those of the 
 human species in shape and structure. They differ, however, some- 
 what in size, being usually rather smaller than in man. There are 
 but two species in which they are known to be larger than in man, 
 viz., the Indian elephant, in which they are 27^00 of ^^^ inch, and 
 the two-toed sloth {Bradypus didactylus), in which they are ogVo of 
 an inch in diameter. In the musk deer of Java they are smaller 
 than in any other known species, measuring rather less than yg^oo- 
 of an inch. The following is a list showing the size of the red 
 globules of the blood in the principal mammalian species, taken 
 from the measurements of Mr. Gulliver,' 
 
 Diameter of Red Globules in the 
 
 Ape . 
 
 • jj'do of 
 
 an i 
 
 nch. 
 
 Cat . 
 
 • 4iV7irOf 
 
 an inch. 
 
 Horse 
 
 iHUff 
 
 
 
 Fox . 
 
 iiVff 
 
 
 Ox . 
 
 4 A (J 
 
 
 
 Wolf . 
 
 5sW 
 
 
 Sheep 
 
 ssr'oij 
 
 
 
 Elephant . 
 
 J705 
 
 
 Goat . 
 
 B^'oij 
 
 
 
 Red deer 
 
 T(JO-ff_ 
 
 
 Dog . 
 
 FsVff 
 
 
 
 Musk deer . 
 
 • TSoUS 
 
 
 In all these instances the form and general appearance of the 
 globules are the same. The only exception to this rule among the 
 mammalians is in the family of the camelidas (camel, dromedary, 
 lama), in which the globules present an oval outline instead of a 
 circular one. In other respects they resemble the foregoing. 
 
 In the three remaining classes of vertebrate animals, viz., birds, 
 reptiles and fish, the blood-globules differ so much from the above 
 that they can be readily distinguished by microscopic examination. 
 
 In works of William Hewson, Sydenham edition, London, 1846, p. 327. 
 
BLOOD-GLOBULES. 
 
 185 
 
 Blood-globules of Frog. 
 seen edgewise, h. White globule. 
 
 -a. Blood-globule 
 
 They are oval in form, and contain a colorless granular nucleus 
 imbedded in their substance. They are also considerably larger 
 than the blood-globules of the mammalians, particularly in the 
 class of reptiles. In the frog 
 (Fig. 60) they measure joVu 
 of an inch in their long 
 diameter; and in Menohran- 
 chiis, the great water lizard 
 of the northern lakes, ^^^ of 
 an inch. In Proteus angui- 
 nus they attain the size, ac- 
 cording to Dr. Carpenter,' of 
 gi^y of an inch. 
 
 Beside the corpuscles de- 
 scribed above, there are glo- 
 bules of another kind found 
 in the blood, viz., the lokite 
 globules. These globules are 
 very much less numerous 
 than the red ; the proportion 
 
 between the two, in human blood, being one white to two or three 
 hundred red globules. In reptiles, the relative quantity of the 
 w^hite globules is greater, but they are always considerably less 
 abundant than the red. They differ also from the latter in shape, 
 size, color and consistency. They are globular in form, white or 
 colorless, and instead of being homogeneous like the others, their 
 substance is filled everywhere with minute dark molecules which 
 give them a finely granular appearance. (Fig. 54, c.) In size they 
 are considerably larger than the red globules, being about 05V0 of 
 an inch in diameter. They are also more consistent than the others, 
 and do not so easily glide along in the minute currents of a drop of 
 blood under examination, but adhere readily to the surfaces of the 
 glass. If treated with dilute acetic acid, they swell up and become 
 smooth and circular in outline ; and at the same time a separation 
 or partial coagulation seems to take place in the substance of which 
 they are composed, so that an irregular collection of granular 
 matter shows itself in their interior, becoming more divided and 
 broken up as the action of the acetic acid upon the globule is 
 longer continued. (Fig. 61.) This collection of granular matter 
 
 The Microscope and its Revelations, Philadelphia edition, p. 600. 
 
186 
 
 THE BLOOD. 
 
 often assumes a curved or crescentic form, as at «, and sometimes 
 various other irregular shapes. It does not indicate the existence 
 
 of a nucleus in the white 
 
 Fig. 61. 
 
 Whtte Globhles of the Blood; altered by 
 dilute acetic acid- 
 
 Ill 
 
 globule, but is merely an 
 appearance produced by the 
 coagulating and disintegrat- 
 ing action of acetic acid upon 
 the substance of which it is 
 composed. 
 
 The chemical constitution 
 of the white globules, as 
 distinguished from the red, 
 has never been determined ; 
 owing to the small quantity 
 in which they occur, and the 
 difficulty of separating them 
 from the others for purposes 
 of analysis. 
 
 The two kinds of blood- 
 globules, white and red, are to be regarded as distinct and inde- 
 pendent anatomical forms. It has been sometimes supposed that 
 the white globules were converted, by a gradual transformation, 
 into the red. There is, however, no direct evidence of this ; as 
 the transformation has never been seen to take place, either in the 
 human subject or in the mammalia, nor even its intermediate 
 stages satisfactorily observed. When, therefore, in default of any 
 such direct evidence, we are reduced to the surmise which has 
 been adopted by some authors, viz., that the change " takes place 
 too rapidly to be detected by our means of observation,"^ it must 
 be acknowledged that the above opinion has no solid founda- 
 tion. It has been stated by some authors (Kcilliker, Gerlach) 
 that in the blood of the batrachian reptiles there are to be seen 
 certain bodies intermediate in appearance between the white and 
 the red globules, and which represent different stages of transi- 
 tion from one form to the other; but this is not a fact which is 
 generally acknowledged. "We have repeatedly examined, with 
 reference to this point, the fresh blood of the frog, as well as that 
 of the menobranchus, in which the large size of the globules 
 would give every opportunity for detecting any such changes, did 
 
 ' Kolliker, Handbuch der Gewebelelire, Leipzig, 1852, p. 582. 
 
BLOOD-GLOBULES. — PLASMA. 187 
 
 they really exist; and it is our unavoidable conclusion from these 
 observations, that there is no good evidence, even in the blood of 
 reptiles, of any sucli transformation taking place. There is simply, 
 as in human blood, a certain variation in size and opacit}'- among 
 the red globules; but no such connection with, or resemblance to, 
 the white globules as to indicate a passage from one form to the 
 other. The red and white globules are therefore to be regarded as 
 distinct and independent anatomical elements. They are mingled 
 together in the blood just as capillary bloodvessels and nerves are 
 mino-led in areolar tissue; but there is no other connection between 
 them, so far as their formation is concerned, than that of juxtapo- 
 sition. 
 
 Neither is it at all probable that the red globules are produced or 
 destroyed in any particular part of the body. One ground for the 
 belief that these bodies were produced by a metamorphosis of the 
 white globules was a supposition that they were continually and 
 rapidly destroyed somewhere in the circulation ; and as this loss 
 must be as rapidly counterbalanced by the formation of new glo- 
 bules, and as no other probable source of their reproduction ap- 
 peared, they were supposed to be produced by transformation of 
 the white globules. But there is no reason for believing that the 
 red globules of the blood are any less permanent, as anatomical 
 forms, than tbe muscular fibres or the nervous filaments. They 
 undergo, it is true, like all the constituent parts of the body, a 
 constant interstitial metamorphosis. They absorb incessantly nu- 
 tritious materials from the blood, and give up to the circulating 
 fluid, at the same time, other substances which result from their 
 internal waste and disintegration. But they do not, so far as we 
 know, perish bodily in any part of the circulation. It is not the 
 anatomical forms^ anywhere, which undergo destruction and reno- 
 vation in the nutritive process; but only the proximate principles of 
 tvhich they are composed. The effect of this interstitial nutrition, 
 therefore, in the blood-globules as in the various solid tissues, is 
 merely to maintain them in a natural and healthy condition of 
 integrity. 
 
 PLASMA. 
 
 The plasma of the blood, according to Lehmann, has the follow- 
 ing constitution: — 
 
188 
 
 THE BLOOD. 
 
 Composition of the Plasma in 1000 Parts. 
 
 Water •. . . . 902.90 
 
 Fibrin 4.05 
 
 Albumen 78.84 
 
 Fatty matters 1.72 
 
 Undetermined (extractive) matters . . . . . . 3.94 
 
 Chloride of sodium ........ 
 
 " potassium ....... 
 
 Phosphates of soda and potass ...... 
 
 Sulphates " " 
 
 Phosphate of lime ........ 
 
 " magnesia ....... 
 
 8.55 
 
 1000.00 
 
 The above ingredients are all intimately mingled in the blood- 
 plasma, in a fluid form, by mutual solution; but they may be 
 separated from each other for examination by appropriate means. 
 The two ingredients belonging to the class of organic substances 
 are the fibrin and the albumen. 
 
 The fibrin^ though present in small quantity, is evidently an 
 important element in the constitution of the blood. It may be ob- 
 tained in a tolerably pure form by gently stirring freshly drawn 
 blood with a glass rod or a bundle of twigs; upon which the 
 fibrin coagulates, and adheres to the twigs in the form of slender 
 threads and flakes. The fibrin, thus coagulated, is at first colored 
 red by the haematine of the blood globules entangled in it ; but 
 it may be washed colorless by a few hours' soaking in running 
 
 water. The fibrin then pre- 
 
 Fig. 62. 
 
 Coagulated Fibrin, sliowing its fibrillated con- 
 dition. 
 
 sents itself under the form 
 of nearly white threads and 
 flakes, having a semi-solid 
 consistency, and a consider- 
 able degree of elasticity. 
 
 The coagulation of fibrin 
 takes place in a peculiar 
 manner. It does not solidify 
 in a perfectly homogeneous 
 mass; but if examined by the 
 microscope in thin layers it 
 is seen to have a fibroid or 
 filamentous texture. In this 
 condition it is said to be 
 " fibrillated." (Fig. 62.) The 
 
PLASMA. 189 
 
 filaments of which it is composed are colorless and elastic, and 
 when isolated are seen to be exceedingly minute, being not more 
 than 4o^^^Tj or 6ven ^^-J-^xr of ^^ i^ich in diameter. They are in 
 part arranged so as to lie parallel with each other; but are more 
 generally interlaced in a kind of irregular network, crossing each 
 other in every direction. On the addition of dilute acetic acid, they 
 swell up and fuse together into a homogeneous mass, but do not dis- 
 solve. They are often interspersed everywhere with minute granu- 
 lar molecules, which render their outlines more or less obscure. 
 
 Once coagulated, fibrin is insoluble in water and can only be 
 again liquefied by the action of an alkaline or strongly saline 
 solution, or by prolonged boiling at a very high temperature. 
 These agents, however, produce a complete alteration in the proper- 
 ties of the fibrin, and after being subjected to them it is no longer 
 the same substance as before. 
 
 The quantity of fibrin in the blood varies in different parts of the 
 body. According to the observations of various writers,' there is 
 more fibrin generally in arterial than in venous blood. The blood 
 of the veins near the heart, again, contains a smaller proportion of 
 fibrin than those at a distance. The blood of the portal vein con- 
 tains less than that of the jugular ; and that of the hepatic vein less 
 than that of the portal. 
 
 The albumen is undoubtedly the most important ingredient of the 
 plasma, judging both from its nature and the abundance in which 
 it occurs. It coagulates at once on being heated to 160° P., or by 
 contact with alcohol, the mineral acids, the metallic salts, or with 
 ferrocyanide of potassium in an acidulated solution. It exists 
 naturally in the plasma in a fluid form by reason of its union with 
 water. The greater part of the water of the plasma, in fact, is in 
 union with the albumen ; and when the albumen coagulates, the 
 water remains united with it, and assumes at the same time the 
 solid form. If the plasma of the blood, therefore, after the removal 
 of the fibrin, be exposed to the temperature of 160° F., it solidifies 
 almost completely ; so that only a few drops of water remain that 
 can be drained away from the coagulated mass. The phosphates 
 of lime and magnesia are also held in solution principally by the 
 albumen, and are retained by it in coagulation. 
 
 The fatty matters exist in the blood mostly in a saponified form, 
 excepting soon after the digestion of food rich in fat. At that 
 period, as we have already mentioned, the emulsioned fat finds its way 
 
 ' Robin and Verdeil, op. cit., vol. ii. p. 202. 
 
190 THE BLOOD. 
 
 into the blood, and circulates for a time unchanged. Afterward it 
 disappears as free fat, and remains partly in the saponified condition. 
 
 The saline ingredients of the plasma are of the same nature with 
 those existing in the globules. The chlorides of sodium and 
 potassium, and the phosphates of soda and potass are the most 
 abundant in both, while the sulphates are present only in minute 
 quantity. The proportions in which the various salts are present 
 are very different, according to Lehmann,^ in the blood-globules 
 and in the plasma. Chloride of potassium is most abundant 
 in the globules, chloride of sodium in the plasma. The phos- 
 phates of soda and potass are more abundant in the globules than 
 in the plasma. On the other hand, the phosphates of lime and 
 magnesia are more abundant in the plasma than in the globules. 
 
 The substances known under the name of extractive matters consist 
 of a mixture of different ingredients, belonging mostly to the class 
 of organic substances, which have not yet been separated in a state 
 of sufficient purity to admit of their being thoroughly examined 
 and distinguished from each other. They do not exist in great 
 abundance, but are -undoubtedly of considerable importance in the 
 constitution of the blood. Beside the substances enumerated in the 
 above list, there are still others which occur in small quantity as 
 ingredients of the blood. Among the most important are the 
 alkaline carbonates, which are held in solution in the serum. It has 
 ■already been mentioned that while the phosphates are most 
 abundant in the blood of the carnivora, the carbonates are most 
 abundant in that of the herbivora. Thus Lehmann^ found car- 
 bonate of soda in the blood of the ox in the proportion of 1.628 per 
 thousand parts. There are also to be found, in solution in the 
 blood, urea, urate of soda, creatine, creatinine, sugar, &c.; all of them 
 ci-ystallizable substances derived from the transformation of other 
 ingredients of the blood, or of the tissues through which it circu- 
 lates. The relative quantity, however, of these substances is very 
 minute, and has not yet been determined with precision. 
 
 COAGULATION OF THE BLOOD. 
 
 A few moments after the blood has been withdrawn from the 
 vessels, a remarkable phenomenon presents itself, viz., its coagula- 
 tion or clotting. This process commences at nearly the same time 
 
 ' Op. cit . voL i. p. 546. ' Op. cit., vol. i. p. 393. 
 
COAGULATION OF THE BLOOD. 191 
 
 throughout the whole mass of the blood. The blood becomes first 
 somewhat diminished in fluidity, so that it will not run over the 
 edge of the vessel, when slightly inclined ; and its surface may be 
 gently depressed with the end of the finger or a glass rod. It then 
 becomes rapidly thicker, and at last solidifies into a uniformly red, 
 opaque, consistent, gelatinous mass, which takes the form of the 
 vessel in which the blood was received. Its coagulation is then 
 complete. The process usually commences, in the human subject, 
 in about fifteen minutes after the blood has been drawn, and is 
 completed in about twenty minutes. 
 
 The coagulation of the blood is dependent entirely upon the 
 presence of the fibrin. This fact has been demonstrated in various 
 ways. In the first place, if frog's blood be filtered, so as to separate 
 the globules and leave them upon the filter, while the plasma is 
 allowed to run through, the colorless filtered fluid which contains 
 the fibrin soon coagulates ; while no coagulation takes place in the 
 moist globules remaining on the filter. Again, if the freshly drawn 
 blood be stirred with a bundle of rods, as we have already de- 
 scribed above, the fibrin coagulates upon them by itself, while the 
 rest of the plasma, mixed with the globules, remains perfectly fluid. 
 It is the fibrin, therefore, which, by its own coagulation, induces 
 the solidification of the entire blood. As the fibrin is uniformly 
 distributed throughout the blood, when its coagulation takes place 
 the minute filaments which make their appearance in it entangle 
 in their meshes the globules and the albuminous fluids of the 
 plasma. A very small quantity of fibrin, therefore, is sufficient to 
 entangle by its coagulation all the fluid and semi-fluid parts of the 
 blood, and convert the whole into a volumi- 
 nous, trembling, jelly-like mass, which is Fig. 63. 
 known by the name of the " crassamentum" 
 or " clot." (Fig. 63.) 
 
 As soon as the clot has fairly formed, it 
 begins to contract and diminish in size. Ex- 
 actly how this contraction of the clot is pro- 
 duced, we are unable to say ; but it is proba- 
 bly a continuation of the same process by 
 which its solidification is at first accomplished, b,^i „f ^^^^^^^^ p^^^^. 
 or at least one very similar to it. As the lated blood, showing the 
 
 . ,• 1 ,1 11 • n ■ ^ whole mass uniformly solidi- 
 
 contraction proceeds, the albuminous fluids ged. 
 
 begin to be pressed out from the meshes in 
 
 which they were entangled. A few isolated drops first appear on 
 
192 
 
 THE BLOOD. 
 
 Fig. 64. 
 
 the surface of the clot. These drops soon increase in size and be- 
 come more numerous. They run together and coalesce with each 
 other, as more and more fluid exudes from the coagulated mass, 
 until the whole surface of the clot is covered with a thin layer of 
 fluid. The clot at first adheres pretty strongly to the sides of the 
 vessel into which the blood was drawn ; but as its contraction goes 
 on, its edges are separated, and the fluid continues to exude between 
 it and the sides of the vessel. This exudation 
 continues for ten or twelve hours; the clot 
 growing constantly smaller and firmer, and 
 the expressed fluid more and more abundant. 
 The globules, owing to their greater con- 
 sistency, do not escape with the albuminous 
 fluids, but remain entangled in the fibrinous 
 coagulum. Finally, at the end of ten or 
 twelve hours the whole of the blood has usu- 
 ally separated into two parts, viz., the clot, 
 which is a red, opaque, dense and resisting, 
 semi-solid mass, consisting of the fibrin and 
 the blood-globules; and the serum, which is a 
 transparent, nearly colorless fluid, containing the water, albumen, 
 and saline matters of the plasma. (Fig. 64.) 
 
 The change of the blood in coagulation may therefore be ex- 
 pressed as follows : — 
 
 Bowl of Coagulated 
 Blood, after twelve hours ; 
 showing the clot contracted 
 and floating iu the fluid serum. 
 
 Before coagulation the blood consists of 
 
 1st. Globules ; and 2d. Plasma — containing 
 
 After coagulation it is separated into 
 
 1st. Clot, containing i 
 
 Fibrin and 
 I Globules ; 
 
 Fibrin, 
 Albumen, 
 Water, 
 Salts. 
 
 ( Albumen, 
 
 and 2d. Serum, containing -^ Water, 
 i Salts. 
 
 The coagulation of the blood is hastened or retarded by various 
 physical conditions, which have been studied with care by various 
 observers, but more particularly by Kobin and Yerdeil. The con- 
 ditions which influence the rapidity of coagulation are as follows : 
 First, the rapidity with which the blood is drawn from the vein, 
 and the size of the orifice from which it flows. If blood be drawn 
 rapidly, in a full stream, from a large orifice, it remains fluid for a 
 comparatively long time ; if it be drawn slowly, from a narrow 
 
COAGULATION OF THE BLOOD. 193 
 
 orifice, it coagulates quickly. Tlius it usually happens that in the 
 operation of venesection, the blood drawn immediately after the 
 opening of the vein runs freely and coagulates slowly; while that 
 which is drawn toward the end of the operation, when the tension 
 of the veins has been relieved and the blood trickles slowly from 
 the wound, coagulates quickly. Secondly, the shape of the vessel 
 into which the blood is received and the condition of its internal 
 surface. The greater the extent of surface over which the blood 
 comes in contact with the vessel, the more is its coagulation 
 hastened. Thus, if the blood be allowed to flow into a tall, narrow, 
 cylindrical vessel, or into a shallow plate, it coagulates more rapidly 
 than if it be received into a hemispherical bowl, in which the ex- 
 tent of surface is less, in proportion to the entire quantity of blood 
 which it contains. For the same reason, coagulation takes place 
 more rapidly in a vessel with a roughened internal surface, than in 
 one which is smooth and polished. The blood coagulates most 
 rapidly when spread out in thin layers, and entangled among the 
 fibres of cloth or sponges. For the same reason, also, hemorrhage 
 continues longer from an incised wound than from a lacerated one; 
 because the blood, in flowing over the ragged edges of the lacer- 
 ated bloodvessels and tissues, solidifies upon them readily, and thus 
 blocks up the wound. 
 
 In all these cases, there is an inverse relation between the rapidity 
 of coagulation and the firmness of the clot. When coagulation 
 takes place slowly, the clot afterward becomes small and dense, and 
 the serum is abundant. When coagulation is rapid, there is but 
 little contraction of the coagulum, an imperfect separation of the 
 serum, and the clot remains large, soft and gelatinous. 
 
 It is well known to practical physicians that a similar relation 
 exists when the coagulation of the blood is hastened or retarded by 
 disease. In cases of -lingering and exhausting illness, or in diseases 
 of a typhoid or exanthematous character, with much depression of 
 the vital powers, the blood coagulates rapidly and the clot remains 
 soft. In cases of active inflammatory disease, as pleurisy or 
 pneumonia, occurring in previously healthy subjects, the blood 
 coagulates slowly, and the clot becomes very firm. In every 
 instance, the blood which has coagulated liquefies again at the 
 commencement of putrefaction. 
 
 The coagulation of the fibrin is not a commencement of organization. 
 The filaments already described, which show themselves in the clot 
 (Fig. 62), are not, properly speaking, organized fibres, and are en- 
 13 
 
194 THE BLOOD. 
 
 tirely different in their character from the fibres of areolar tissue, or 
 any other normal anatomical elements. They are simply the ultimate 
 form which fibrin assumes in coagulating, just as albumen takes the 
 form of granules under the same circumstances. The coagulation 
 of fibrin does not differ in character from that of any other organic 
 substance ; it merely difi'ers in the physical conditions which give 
 rise to it. All the coagulable organic substances are naturally fluid, 
 and coagulate only when they are placed under certain unusual con- 
 ditions. But the particular conditions necessary for coagulation 
 vary with the different organic substances. Thus albumen coagu- 
 lates by the application of heat. Casein, which is not affected by 
 heat, coagulates by contact with an acid body. Pancreatine, again, 
 is coagulated by contact with sulphate of magnesia, which has no 
 efieet on albumen. So fibrin, which is naturally fluid, and which 
 remains fluid so long as it is circulating in the vessels, coagulates 
 when it is withdrawn from them and brought in contact with 
 unnatural surfaces. Its coagulation, therefore, is no more " sponta- 
 neous," properly speaking, than that of any other organic substance. 
 Still less does it indicate anything like organization, or even a 
 commencement of it. On the contrary, in the natural processes of 
 nutrition, fibrin is assimilated by the tissues and takes part in their 
 organization, only when it is absorbed by them from the blood- 
 vessels in a fluid form. As soon as it is once coagulated by any 
 means, it passes into an unnatural condition, and must be again 
 liquefied and absorbed into the blood before it can be assimilated. 
 
 As the fibrin, therefore, is maintained in its natural condition of 
 fluidity by the movement of the circulating blood in the interior of 
 the vessels, anything which interferes with this circulation will 
 induce its coagulation. If a ligature be placed upon an artery in 
 the living subject, the blood which stagnates above the ligature 
 coagulates just as it would do if entirely removed from the circula- 
 tion. If the vessel be ruptured or lacerated, the blood which 
 escapes from it into the areolar tissue coagulates, because here also 
 it is withdrawn from the circulation. It coagulates also in the 
 interior of the vessels after death owing to the same cause, viz : 
 stoppage of the circulation. During the last moments of life, when 
 the flow of blood through the cavities of the heart is impeded, the 
 fibrin often coagulates, in greater or less abundance, upon the 
 moving chordss tendineas and the edges of the valves, just as it 
 would do if withdrawn from the body and stirred with a bundle 
 of twigs. In every instance, the coagulation of the fibrin is a 
 
COAGULATION OF THE BLOOD. 
 
 195 
 
 Vertical section of a. R e- 
 
 CENT COAGCLCM, showing 
 
 the greater accumulation of 
 blood-globules at the bottom. 
 
 morbid phenomenon, dependent on the cessation or disturbance of 
 the circulation. 
 
 If the blood be allowed to coagulate in a bowl, and the clot be 
 then divided by a vertical section, it will 
 be seen that its lower portion is softer and 
 of a deeper red than the upper. (Fig. 65.) 
 This is because the globules, which are of 
 greater specific gravity than the plasma, sink 
 toward the bottom of the vessel before coagu- 
 lation takes place, and accumulate in the 
 lower portion of the blood. This deposit of 
 the globules, however, is only partial; be- 
 cause they are soon fixed and entangled by 
 the solid mass of the coagulum, and thus 
 retained in the position in which they hap- 
 pened to be at the moment that coagulation occurred. 
 
 If the coagulation, however, be delayed longer than usual, or if 
 the globules sink more rapidly than is customary, they will have 
 time to subside entirely from the upper portion of the blood, 
 leaving a layer at the surface which is composed of plasma alone. 
 When coagulation then takes place, this upper portion solidifies 
 at the same time with the rest, and the clot then presents two dif- 
 ferent portions, viz., a lower portion of a dark red color, in which 
 the globules are accumulated, and an upper portion from which the 
 globules have subsided, and which is of a grayish white color and 
 partially transparent. This whitish layer on the surface of the clot 
 is termed the " buffy coat ;" and the blood presenting it is said to 
 be " buffed." It is an appearance which often presents itself in 
 cases of acute inflammatory disease, in which the coagulation of the 
 blood is unusually retarded. 
 
 When a clot with a buffy coat begins to 
 contract, the contraction takes place perfectly 
 well in its upper portion, but in the lower 
 part it is impeded by the presence of the 
 globules which have accumulated in large 
 quantity at the bottom of the clot. While 
 the lower part of the coagulum, therefore, 
 remains voluminous, and hardly separates 
 from the sides of the vessel, its upper color- 
 less portion diminishes very much in size ; 
 and as its edges separate from the sides of the vessel, they curl over 
 
 Bowl of CoAOtlLATED 
 
 Blood, showing the clot 
 buffed and cupped. 
 
196 THE BLOOD. 
 
 toward each other, so that the upper surface of the clot becomes 
 more or less excavated or cup-shaped. (Fig. 66.) The blood is then 
 said to be " buffed and cupped." These appearances do not present 
 themselves under ordinary conditions, but only when the blood has 
 become altered by disease. 
 
 The entire quantity of blood existing in the body has never been 
 very accurately ascertained. It is not possible to extract the whole 
 of it by opening the large vessels, since a certain portion will always 
 remain in the cavities of the heart, in the veins, and in the capil- 
 laries of the head and abdominal organs. The other methods 
 which have been practised or proposed from time to time are all 
 liable to some practical objection. We have accordingly only 
 been able thus far to ascertain the minimum quantity of blood 
 existing in the body. Weber and Lehmann^ ascertained as nearly 
 as possible the quantity of blood in two criminals who suflered 
 death by decapitation ; in both of which cases they obtained essen- 
 tially similar results. The body weighed before decapitation 133 
 pounds avoirdupois. The blood which escaped from the vessels at 
 the time of decapitation amounted to 12.27 pounds. In order to 
 estimate the quantity of blood which remained in the vessels, the 
 experimenters then injected the arteries of the head and trunk with 
 water, collected the watery fluid as it escaped from the veins, and 
 ascertained how much solid matter it held in solution. This 
 amounted to 477.22 grains, which corresponded to 4.38 pounds of 
 blood. The result of the experiment is therefore as follows : — 
 
 Blood which escaped from the vessels . . . . .12.27 pounds. 
 " remained in the body ..... 4.38 " 
 
 Whole quantity of blood in the living body, 16.65 
 
 The weight of the blood, then, in proportion to the entire weight 
 of the body, was as 1 : 8 ; and the body of a healthy man, weighing 
 140 pounds, will therefore contain on the average at least 17J 
 pounds of blood. 
 
 ' Physiological Chemistry, vol. i. p. 638. 
 
RESPIRATION". 197 
 
 CHAPTER XII. 
 
 RESPIRATION. 
 
 The blood as it circulates in the arterial system has a bright 
 scarlet color ; but as it passes through the capillaries it gradually 
 becomes darker, and on its arrival in the veins its color is a deep 
 purple, and in some parts of the body nearly black. There are, 
 therefore, two kinds of blood in the body ; arterial blood, which is 
 of a bright color, and venous blood, which is dark. Now it is found 
 that the dark-colored venous blood, which has been contaminated 
 by passing through the capillaries, is unfit for further circulation. 
 It is incapable, in this state, of supplying the organs with their 
 healthy stimulus and nutrition, and has become, oh the contrary, 
 deleterious and poisonous. It is accordingly carried back to the 
 heart by the veins, and thence sent to the lungs, where it is recon- 
 verted into arterial blood. The process by which the venous blood 
 is thus arterialized and renovated, is known as the process of re- 
 spiration. 
 
 This process takes place very actively in the higher animals, and 
 probably does so to a greater or less extent in all animals without 
 exception. Its essential conditions are that the circulating fluid 
 should be exposed to the influence of atmospheric air, or of an 
 aerated fluid ; that is, of a fluid holding atmospheric air or oxygen 
 in solution. The respiratory apparatus consists essentially of a 
 moist and permeable animal membrane, the respiratory membrane, 
 with the bloodvessels on one side of it, and the air or aerated fluid 
 on the other. The blood and the air, consequently, do not come in 
 direct contact with each other, but absorption and exhalation take 
 place from one to the other through the thin membrane which lies 
 between. 
 
 The special anatomical arrangement of the respiratory apparatus 
 differs in different species of animals. In most of those inhabiting 
 the water, the respiratory organs have the form of gills or branchice ; 
 that is, delicate filamentous prolongations of some part of the 
 
198 
 
 EESPIEATION. 
 
 Head and Gills op Menobranchus. 
 
 integument or mucous membranes, wlaich contain an abundant 
 supply of bloodvessels, and which hang out freely into the sur- 
 rounding water. In many kinds of aquatic lizards, as, for exam- 
 ple, in menohranchus (Fig. 67), 
 '^* there are upon each side of the 
 
 neck three delicate feathery 
 tufts of thread-like prolonga- 
 tions from the mucous mem- 
 brane of the pharynx, which 
 pass out through fissures in 
 the side of the neck. Each 
 tuft is composed of a prin- 
 cipal stem, upon which the 
 filaments are arranged in a 
 pinnated form, like the plume upon the shaft of a feather. Each 
 filament, when examined by itself, is seen to consist of a thin, rib- 
 bon-shaped, double fold of mucous membrane, in the interior of 
 which there is a plentiful network of minute bloodvessels. The 
 dark blood, as it comes into the filament from the branchial artery, 
 is exposed to the influence of the water in which the filament is 
 bathed, and as it circulates through the capillary network of the 
 gills is reconverted into arterial blood. It is then carried away by 
 the branchial vein, and passes into the general current of the cir- 
 culation. The apparatus is further supplied with a cartilaginous 
 framework, and a set of muscles by which the gills are gently waved 
 about in the surrounding water, and constantly brought into con- 
 tact with fresh portions of the aerated fluid. 
 
 Most of the aquatic animals breathe by gills similar in all their 
 essential characters to those described above. In terrestrial and 
 air-breathing animals, however, the respiratory apparatus is situated 
 internally. In them, the air is made to penetrate into the interior 
 of the body, into certain cavities or sacs called the lungs, which 
 are lined with a vascular mucous membrane. In the salamanders, 
 for example, which, though aquatic in their habits, are air-breathing 
 animals, the lungs are two long cylindrical sacs, running nearly the 
 entire length of the body, commencing anteriorly by a communi- 
 cation with the pharynx, and terminating by rounded extremities 
 at the posterior part of the abdomen. These lungs, or air-sacs, 
 have a smooth internal surface; and the blood which circulates 
 through their vessels is arterialized by exposure to the air contained 
 in their cavities. The air is forced into the lungs by a kind of 
 
EESPIEATION. 
 
 199 
 
 Fig. 68. 
 
 swallowing movement, and is after a time regurgitated and dis- 
 charged, in order to make room for a fresh supply. 
 
 In the frog, tortoise, serpents, &c., the structure of the lung is a 
 little more complicated, since respiration is more active in these 
 animals, and a more perfect organ is requisite to accomplish the 
 arterialization of the blood. In these animals, the cavity of the lung, 
 instead of being simple, is divided by incomplete partitions into a 
 number of smaller cavities or " cells." The cells all communicate 
 with the central pulmonary cavity; and the partitions, which join 
 each other at various angles, are all composed of thin, projecting, 
 double folds of the lining membrane, with bloodvessels ramifying 
 between them. (Fig. 68.) By this arrangement, 
 the extent of surface presented to the air by the 
 pulmonary membrane isjnuch increased, and the 
 arterialization of the blood takes place with a 
 corresponding degree of rapidity. 
 
 In the human subject, and in all the warm- 
 blooded quadrupeds, the lungs are constructed 
 on a plan which is essentially similar to the 
 above, and which differs from it only in the 
 greater extent to which the pulmonary cavity is 
 subdivided, and the surface of the respiratory 
 membrane increased. The respiratory apparatus 
 (Fig. 69) commences with the larynx, which 
 communicates with the pharynx at the upper part of the neck. 
 Then follows the trachea, a membranous tube with cartilaginous 
 rings; which, upon its entrance into the chest, divides into the right 
 and left bronchus. These again divide successively into second- 
 ary and tertiary bronchi; the subdivision continuing, while the 
 bronchial tubes grow smaller and more numerous, and separate 
 constantly from each other. As they diminish in size, the tubes 
 grow more delicate in structure, and the cartilaginous rings and 
 plates disappear from their walls. They are finally reduced, accord- 
 ing to KoUiker, to the size of ^^ of an inch in diameter ; and are 
 composed only of a thin mucous membrane, lined with pavement 
 epithelium, which rests upon an elastic fibrous layer. They are 
 then known as the "ultimate bronchial tubes." 
 
 Each ultimate bronchial tube terminates in a division or islet of 
 the pulmonary tissue, about y'^ of an inch in diameter, which is 
 termed a "pulmonary lobule." Each pulmonary lobule resembles 
 in its structure the entire frog's lung in miniature. It consists of a 
 
 Lung of Froo, 
 showing its internal sur- 
 face 
 
200 
 
 EESPIEATIOX. 
 Fig. 69. 
 
 Fig. 70. 
 
 Human Larynx, Trachea, Bronchi, and Lungs; showing the ramification of the 
 bronchi, and the division of the lungs into lobules. 
 
 vascular membrane inclosing a cavity; which cavity is divided 
 into a large number of secondary compartments by thin septa or 
 partitions, which project from its internal surface. (Fig. 70.) These 
 secondary cavities are the " pulmonary 
 cells," or " vesicles." Each vesicle is about 
 ^-g of an inch in diameter; and is covered 
 on its exterior with a close network of ca- 
 pillary bloodvessels, which dip down into 
 the spaces between the adjacent vesicles, and 
 expose in this way a double surface to the 
 air which is contained in their cavities. 
 Between the vesicles, and in the interstices 
 between the lobules, there is a large quan- 
 tity of yellow elastic tissue, which gives 
 firmness and resiliency to the pulmonary 
 structure. The pulmonary vesicles, accord- 
 siNGLE LoBCLE OF Hu- • ^^ ^j^g obscrvatious of Kdlliker, are 
 
 MAN Lung. — a. Ultimate bron- ° _ ' 
 
 chiaitube. h. Cavity of lobule, lined cvcrywhcre with a layer of pavement 
 
 c,j,c. Pulmonary cells, or vesi- epithelium, COUtinUOUS with that in the 
 
RESPIKATORY MOVEMENTS OF THE CHEST. 201 
 
 ultimate bronchial tubes. The whole extent of respiratory sur- 
 hce in both lungs has been calculated by Lieberkiihn' at 'fourteen 
 hundred square feet. It is plainly impossible to make a precisely 
 accurate calculation of this extent; but there is every reason to 
 believe that the estimate adopted by Lieberkiihn, regarded as 
 approximative, is not by any means an exaggerated one. The 
 great multiplication of the minute pulmonary vesicles, and of the 
 partitions between them, must evidently increase to an extraor- 
 dinary degree the extent of surface over which the blood, spread 
 out in a thin layer, is exposed to the action of the air. These 
 anatomical conditions are, therefore, the most favorable to its rapid 
 and complete arterialization. 
 
 Respiratory Movements of the Chest. — The air which is con- 
 tained in the pulmonary lobules and vesicles becomes rapidly vitiated 
 in the process of respiration, and requires therefore to be expelled 
 and replaced by a fresh supply. This exchange or renovation of 
 the air is effected by alternate movements of the chest, of expansion 
 and collapse, which are termed the " respiratory movements of the 
 chest." The expansion of the chest is effected by two sets of mus- 
 cles, viz., first, the diaphragm, and, second, the intercostals. While 
 the diaphragm is in a state of relaxation, it has the form of a vaulted 
 partition between the thorax and abdomen, the edges of which are 
 attached to the inferior extremity of the sternum, the inferior 
 costal cartilages, the borders of the lower ribs and the bodies of 
 the lumbar vertebne, while its convexity rises high into the cavity 
 of the chest, as far as the level of the fifth rib. When the fibres 
 of the diaphragm contract, their curvature is necessarily dimi- 
 nished; and they approximate a straight line, exactly in proportion 
 to the extent of their contraction. Consequently, the entire con- 
 vexity of the diaphragm is diminished in the same proportion; 
 and it descends toward the abdomen, enlarging the cavity of the 
 chest from above downward, (i^'ig. 71.) At the same time the inter- 
 costal muscles enlarge it in a lateral direction. For the ribs, arti- 
 culated behind with the bodies of the vertebrge, and joined in front 
 to the sternum by the flexible and elastic costal cartilages, are so 
 arranged that, in a position of rest, their convexities look obliquely 
 outward and downward. When the movement of inspiration is 
 about to commence, the first rib is fixed by the contraction of the 
 
 ' In Simon's Chemistry of Man, Philada. ed., 1846, p. 109. 
 
202 
 
 RESPIRATION. 
 
 Fig. 71. 
 
 scaleni muscles, and the intercostal muscles then contracting simul- 
 taneously, the ribs are drawn upward. In this movement, as each 
 rib rotates upon its articulation with the 
 spinal column at one extremity, and with 
 the sternum at the other, its convexity is 
 necessarily carried outward at the same 
 time that it is drawn upward, and the pa- 
 rietes of the chest are, therefore, expanded 
 laterally. The sternum itself rises slightly 
 with the same movement, and enlarges to 
 some extent the antero-posterior diameter 
 of the thorax. By the simultaneous action, 
 therefore, of the diaphragm which descends, 
 and of the intercostal muscles which lift 
 the ribs and the sternum, the cavity of the 
 chest is expanded in every direction, and 
 the air passes inward, through the trachea 
 and bronchial tubes, by the simple force of 
 aspiration. 
 
 After the movement of inspiration is ac- 
 complished, and the lungs are filled with 
 air, the diaphragm and intercostal muscles 
 relax, and a movement of expiration takes 
 place, by which the chest is partially col- 
 lapsed, and a portion of the air contained 
 in the pulmonary cavity expelled. The 
 movement of expiration is entirely a passive 
 one, and is accomplished by the action of 
 three different forces. First, the abdominal 
 organs, which have been pushed out of their 
 usual position by the descent of the diaphragm, fall backward by 
 their own weight and carry upward the relaxed diaphragm before 
 them. Secondly, the costal cartilages, which are slightly twisted 
 out of shape when the ribs are drawn upward, resume their natural 
 position as soon as the muscles are relaxed, and, drawing the ribs 
 down again, compress the sides of the chest. Thirdly, the pul- 
 monary tissue, as we have already remarked, is abundantly sup- 
 plied with yellow elastic fibres, which retract by virtue of their 
 own elasticity, in every part of the lungs, after they have been 
 forcibly distended, and, compressing the pulmonary vesicles, drive 
 out a portion of the air which they contained. By the constant 
 
 Diagram illustratingi 
 
 THE ReSPIRATORT MOVE- 
 MENTS. — a. Cavity of the chest. 
 h. Diaphragm. The dark out- 
 lines show the figure of the chest 
 when collapsed ; the dotted lines 
 show the same when expanded. 
 
RESPIEATOEY MOVEMENTS OF THE CHEST. 203 
 
 recurrence of these alternating movements of inspiration and expi- 
 ration, fresh portions of air are constantly introduced into and 
 expelled from the chest. 
 
 The whole of the air, however, is not exchanged at each move- 
 ment of respiration. On the contrary, a very considerable quantity 
 remains in the pulmonary cavity after the most complete expira- 
 tion; and even after the lungs have been removed from the chest, 
 they still contain a large quantity of air which cannot be entirely 
 displaced by any violence short of disintegrating and disorganizing 
 the pulmonary tissue. It is evident, therefore, that only a com- 
 paratively small portion of the air in the lungs passes in and out 
 with each respiratory movement ; and it will require several suc- 
 cessive respirations before all the air in the chest can be entirely 
 changed. It has not been possible to ascertain with certainty the 
 exact proportion in volume which exists between the air which is 
 alternately inspired and expired, or "tidal" air, and that which 
 remains constantly in the chest, or "residual" air, as it is called. 
 It has been estimated, however, by Dr. Carpenter,^ from the reports 
 of various observers, that the volume of inspired and expired air 
 varies from 10 to 13 per cent, of the entire quantity contained in 
 the chest. If this estimate be correct, it will require from eight to 
 ten respirations to change the whole quantity of air in the cavity 
 of the chest. 
 
 It is evident, however, from the foregoing, that the inspiratory 
 and expiratory movements of the chest cannot be sufficient to 
 change the air at all in the pulmonary l©bules and vesicles. The 
 air which is drawn* in with each inspiration penetrates only into 
 the trachea and bronchial tubes, until it occupies the place of that 
 which was driven out by the last expiration. By the ordinary 
 respiratory movements, therefore, only that small portion of the 
 air lying nearest the exterior, in the trachea and large bronchi 
 would fluctuate backward and forward, without ever penetrating 
 into the deeper parts of the lung, were there no other means pro- 
 vided for its renovation. There are, however, two other forces in 
 play for this purpose. The first of these is the diffusive power of 
 the gases themselves. The air remaining in the deeper parts of 
 the chest is richer in carbonic acid and poorer in oxygen than that 
 which has been recently inspired ; and by the laws of gaseous dif- 
 fusion there must be a constant interchange of these gases between 
 
 ' Human Physiology, Philada. ed., 1855, p. 300. 
 
204 EESPIEATION. 
 
 the pulmonary vesicles and the trachea, tending to mix them 
 equally in all parts of the lung. This mutual diffusion and inter- 
 mixture of the gases will therefore tend to renovate, partially at 
 least, the air in the pulmonary lobules and vesicles. Secondly the 
 trachea and bronchial tubes, down to those even of the smallest 
 size, are lined with a mucous membrane which is covered with a 
 ciliated epithelium. The movement of these cilia is found to be 
 directed always from below upward ; and, like ciliary motion 
 wherever it occurs, has the effect of producing a current in the 
 same direction, in the fluids covering the mucous membrane. The 
 
 air in the tubes must partici- 
 Fig- 72. pate, to a certain extent, in 
 
 ■|H|BBHB^BH|HBBBB^H this and a double 
 
 ^^^S^^^^^^^^^H^^^^^^H stream of air therefore is estab- 
 ^KKmljjj^ lished in each bronchial tube; 
 
 ^/^^^BS^S/K^^^^^^^^^ current passing from with- 
 
 ^^^^P^^PI^^^^^^^^^^^B in outward along the walls of 
 ^^^^^M^HHMj^^^^^^^HU the tube, and a return 
 
 ^ . , , passing from without inward, 
 
 Small Bronchial Tube, showing outward r o i 
 
 and inward current, produced by ciliary motion. alono" the Central part of itS 
 
 cavity. (Fig. 72.) By this 
 means a kind of aerial circulation is constantly maintained in the 
 interior of the bronchial tubes ; which, combined with the mutual 
 diffusion of the gases and the alternate expansion and collapse of 
 the chest, effectually accomplish the renovation of the air contained 
 in all parts of the pulmonary cavity. 
 
 Eespiratory Movements of the Glottis. — Beside the move- 
 ments of expansion and collapse already described, belonging to 
 the chest, there are similar respiratory movements which take place 
 in the larynx. If the respiratory passages be examined after death, 
 in the state of collapse in which they are usually found, it will be 
 noticed that the opening of the glottis is very much smaller than 
 the cavity of the trachea below. The glottis itself presents the 
 appearance of a narrow chink, while the passage for the inspired 
 air widens in the lower part of the larynx, and in the trachea 
 constitutes a spacious tube, nearly cylindrical in shape, and over 
 half an inch in diameter. We have found, for instance, that in 
 the human subject the space included between the vocal chords 
 has an area of only 0.15 to 0.17 square inch ; while the calibre 
 of the trachea in the middle of its length is 0.45 square inch. 
 
RESPIRATORY MOVEMENTS OF THE GLOTTIS. 
 
 205 
 
 This disproportion, however, which is so evident after death, does 
 not exist during life. While respiration is going on, there is a 
 constant and regular movement of the vocal chords, synchronous 
 with the inspiratory and expiratory movements of the chest, by 
 
 Fig. 73. 
 
 Fig. 74. 
 
 Human Larynx, viewed from above 
 in its ordinary post-mortem condition. — a. 
 Vocal chords, b. Thyroid cartilage, cc. Ary- 
 tenoid cartilages, o. Opening of the glottis. 
 
 The same, with the glottis opened by 
 separation of the vocal chords. — a. Vocal 
 chords. 6. Thyroid cartilage, vc. Aryte- 
 noid cartilages, o. Opening of the glottis. 
 
 Fig. 75. 
 
 which the size of the glottis is alternately enlarged and diminished. 
 At every inspiration, the glottis opens and allows the air to pass 
 freely into the trachea ; at every expiration it collapses, and the 
 air is driven out through it from be- 
 low. These movements are called the 
 " respiratory movements of the glottis." 
 They correspond in ev«ry respect with 
 those of the chest, and are excited or 
 retarded by similar causes. When- 
 ever the general movements of respira- 
 tion are hurried and labored, those of 
 the glottis become accelerated and in- 
 creased in intensity at the same time ; 
 and when the movements of the chest 
 are slower or fainter than usual, owing 
 to debility, coma, or the like, those of 
 the glottis are diminished in the same 
 proportion. 
 
 1.1 „ „• , ,• ^ii Human Larynx, POSTERIOR 
 n the respiratory motions of the viEw.-a. Thyroid cartilage. 6. Epi- 
 glottis, as in those of the chest, the glottis, cc. Arytenoid cartilages, d. 
 , ry • ... . . Cricoid cartilage, ee. Posterior crico- 
 movement Ot inspiration is an active arytenoid muscles. /. Trachea. 
 
206 EESPIRATION. 
 
 one, and that of expiration passive. In inspiration, the glottis is 
 opened by contraction of the posterior crico-arytenoid muscles. 
 (Fig. 75.) These muscles originate from the posterior surface of 
 the cricoid cartilage, near the median line; and their fibres, running 
 upward and outward, are inserted into the external angle of the 
 arytenoid cartilages. By the contraction of these muscles, during 
 the movement of inspiration, the arytenoid cartilages are rotated 
 upon their articulations with the cricoid, so that their anterior 
 extremities are carried outward, and the vocal chords stretched and 
 separated from each other. (Fig. 74.) In this way, the size of the 
 glottis may be increased from 0.16 to 0.27 square inch. 
 
 In expiration, the posterior crico-arytenoid muscles are relaxed, 
 and the elasticity of the vocal chords brings them back to their 
 former position. 
 
 The motions of respiration consist, therefore, of two sets of move- 
 ments : viz., those of the chest, and those of the glottis. These move- 
 ments, in the natural condition, correspond with each other both in 
 time and intensity. It is at the same time and by the same nervous 
 influence, that the chest expands to inhale the air, while the glottis 
 opens to admit it ; and in expiration, the miiscles of both chest and 
 glottis are relaxed, while the elasticity of the tissues, by a kind of 
 passive contraction, restores the parts to their original condition. 
 
 CHANGES IN THE AIR DURING RESPIRATION. 
 
 The atmospheric air, as it is drawn into the cavity of the lungs, 
 is a mixture of oxygen and nitrogen, in the proportion of about 21 
 per cent., by volume, of oxygen, to 79 per cent, of nitrogen. It 
 also contains about one-twentieth per cent, of carbonic acid, a vary- 
 ing quantity of watery vapor, and some traces of ammonia. If col- 
 lected and examined, after passing through the lungs, it is found to 
 have become altered in the following essential particulars, viz : — 
 
 1st. It has lost oxygen. 
 
 2d. It has gained carbonic acid. And 
 
 3d. It has absorbed the vapor of water. 
 
 Beside the two latter substances, there are also exhaled with the 
 expired air a very small quantity of nitrogen, over and above what 
 was taken in with inspiration, and a little animal matter in a 
 gaseous form, which communicates a slight but peculiar odor to 
 the breath. The air is also somewhat elevated in temperature, by 
 
CHANGES IN THE BLOOD DURING RESPIRATION. 207 
 
 contact with the pulmonary mucous membrane. By far the most 
 important part, however, of the above changes suffered by the air, 
 consists in its loss of ox3^gen, and its absorption of carbonic acid. 
 
 The oxygen which disappears from the inspired air is not entirely 
 replaced in the carbonic acid exhaled ; that is, there is less oxygen 
 in the carbonic acid which is returned to the air by expiration than 
 has been lost during inspiration. 
 
 There is even more oxygen absorbed than is given off again in 
 both the carbonic acid and aqueous vapor together, which are 
 exhaled from the lungs.^ There is, then, a constant disappearance 
 of oxygen from the air used in respiration, and a constant accumu- 
 lation of carbonic acid. 
 
 The proportion of oxygen which disappears in the interior of the 
 body, over and above that which is returned in the breath under 
 the form of carbonic acid, varies in different kinds of animals. In 
 the herbivora, it is about 10 per cent, of the whole amount of oxy- 
 gen inspired ; in the carnivora, 20 or 25 per cent,, and even more. 
 It is a very remarkable fact, also, and an important one, as regards 
 the theory of respiration, that, in the same animal, the proportion of 
 oxygen absorbed, to that of carbonic acid exhaled, varies according 
 to the quality of the food. In dogs, for instance, while fed on ani- 
 mal food, according to the experiments of Eegnault and Eeiset, 25 
 per cent, of the inspired oxygen disappeared in the body of the 
 animal; but when fed on starchy substances, all but 8 per cent, 
 reappeared in the expired carbonic acid. It is already evident, there- 
 fore, from these facts, that the oxygen of the inspired air is not 
 altogether employed in the formation of carbonic acid. 
 
 CHANGES IN THE BLOOD DURING RESPIRATION. 
 
 If we pass from the consideration of the changes produced in the 
 air by respiration to those which take place in the blood during the 
 same process, we find, as might have been expected, that the latter 
 correspond inversely with the former. The blood, in passing 
 through the lungs, suffers the following alterations : — 
 
 1st. Its color is changed from venous to arterial. 
 
 2d. It absorbs oxygen. And 
 
 8d. It exhales carbonic acid and the vapor of water. 
 
 ' Lehmann's Physiological Chemistry, Philada. ed., vol. ii. p. 432. 
 
208 EESPIRATION. 
 
 The interchange of gases, which takes place during respiration 
 between the air and the blood, is a simple phenomenon of absorp- 
 tion and exhalation. The inspired oxygen does not, as Lavoisier 
 once supposed, immediately combine with carbon in the lungs, and 
 return to the atmosphere under the form of carbonic acid. On the 
 contrary, almost the first fact of importance which has been estab- 
 lished by the examination of the blood in this respect is the fol- 
 lowing, viz : that carbonic acid exists ready formed in the venous blood 
 before its entrance into the lungs ; and, on the other hand, that the 
 oxygen which is absorbed during respiration passes off in a free state 
 with the arterial blood. The real process, as it takes place in the 
 lung, is, therefore, for the most part, as follows : The blood comes 
 to the lungs already charged with carbonic acid. In passing through 
 the pulmonary capillaries, it is exposed to the influence of the air 
 in the cavity of the pulmonary cells, and a transudation of gases 
 takes place through the moist animal membranes of the lung. 
 Since the blood in the capillaries contains a larger proportion 
 of carbonic acid than the air in the air-vesicles, a portion of this 
 gas leaves the blood and passes out through the pulmonary mem- 
 brane ; while the oxygen, being more abundant in the air of the 
 vesicles than in the circulating fluid, passes inward at the same 
 time, and is condensed by the blood. 
 
 In this double phenomenon of exhalation and absorption, which 
 takes place in the lungs, both parts of the process are equally 
 necessary to life. It is essential for the constant activity and nutri- 
 tion of the tissues that they be steadily supplied with oxygen by 
 the blood ; and if this supply be cut off, their functional activity 
 ceases. On the other hand, the carbonic acid which is produced in. 
 the body by the processes of nutrition becomes a poisonous sub- 
 stance, if it be allowed to collect in large quantity. Under ordinary 
 circumstances, the carbonic acid is removed by exhalation through 
 the lungs as fast as it is produced in the interior of the body ; but 
 if respiration be suspended, or seriously impeded, since the produc- 
 tion of carbonic acid continues, while its elimination is prevented, 
 it accumulates in the blood and in the tissues, and terminates life 
 in a few moments, by a rapid deterioration of the circulating fluid, 
 and more particularly by its poisonous effect on the nervous system. 
 
 The deleterious effects of breathing in a confined space will 
 therefore very soon become apparent. As respiration goes on, the 
 oxygen of the air constantly diminishes, and the carbonic acid, 
 mingled with it by exhalation, increases in quantity. After a time 
 
CHANGES OF THE BLOOD DURING RESPIRATION. 209 
 
 the air becomes accordingly so poor in oxygen that, by that fact 
 alone, it is incapable of supporting life. At the same time, the 
 carbonic acid becomes so abundant in the air vesicles that it prevents 
 the escape of that which already exists in the blood ; and the dele- 
 terious effect of its accumulation in the circulating fluid is added 
 to that produced by a diminished supply of oxygen. An increased 
 proportion of carbonic acid in the atmosphere is therefore injurious 
 in a similar manner, although there may be no diminution of oxy- 
 gen; since by its presence it impedes the elimination of the carbonic 
 acid already formed in the blood, and induces the poisonous effects 
 which result from its accumulation. 
 
 Examination of the blood shows furthermore that the interchange 
 of gases in the lungs is not complete but only partial in its extent. 
 It results from the experiments of Magendie, Magnus, and others, 
 that both oxygen and carbonic acid are contained in both venous 
 and arterial blood. Magnus' found that the proportion of oxygen 
 to carbonic acid, by volume, in arterial blood was as 10 to 25 ; in 
 venous blood as 10 to 40. The venous blood, then, as it arrives at 
 the lungs, still retains a remnant of the oxygen which it had pre- 
 viously absorbed ; and in passing through the pulmonary capillaries 
 it gives off only a part of the carbonic acid with which it has 
 become charged in the general circulation. 
 
 The. oxygen and carbonic acid of the blood exist in a state of 
 solution in the circulating fluid, and not in a state of intimate chemi- 
 cal combination. This is shown by the fact that both of these 
 substances may be withdrawn from the blood by simple exhaustion 
 with an air pump, or by a stream of any other indifferent gas, such 
 as hydrogen, which possesses sufficient physical displacing power. 
 Magnus found^ that freshly drawn arterial blood yielded by simple 
 agitation with carbonic acid more than 10 per cent, of its volume 
 of oxygen. The carbonic acid may also be expelled from venous 
 blood by a current of pure oxygen, or of hydrogen, or, in great 
 measure, by simple agitation with atmospheric air. There is some 
 difficulty in determining, however, whether the carbonic acid of the 
 blood be altogether in a free state, or whether it be partly in a 
 state of loose chemical combination with a base, under the form of 
 an alkaline bicarbonate. A solution of bicarbonate of soda itself 
 will lose a portion of its carbonic acid, and become reduced to the 
 
 ' In Lehmann, op. cit., vol. i. p. 570. • 
 
 ^ In Robin and Verdeil, op. cit., vol. ii. p. 34. 
 14 
 
210 EESPIRATION". 
 
 condition of a carbonate, bj simple exhaustion under the air-pump, 
 or by agitation with pure hydrogen at the temperature of the body. 
 Lehmann has found' that after the expulsion of all the carbonic 
 acid removable by the air-pump and a current of hydrogen, there 
 still remains, in ox's blood, 0.1628 per cent, of carbonate of soda; 
 and he estimates that this quantity is sufficient to have retained all 
 tbe carbonic acid, previously given off", in the form of a bicarbonate. 
 It makes little or no difference, however, so far ar regards the pro- 
 cess of respiration, whether the carbonic acid of the blood exist in 
 an entirely free state, or under the form of an alkaline bicarbonate ; 
 since it may be readily removed from this combination, at the tem- 
 perature of the body, by contact with an indifferent gas. 
 
 The oxygen and carbonic acid of the blood are in solution prin- 
 cipally in the blood- globules, and not in the plasma. The researches 
 of Magnus have shown^ that the blood holds in solution 2| times 
 as much oxygen as pure water could dissolve at the same tempera- 
 ture; and that while the serum of the blood, separated from the 
 globules, exerts no more solvent power on oxygen than pure water, 
 defibrinated blood, that is, the serum and globules mixed, dissolves 
 quite as much oxygen as the fresh blood itself. The same thing is 
 true with regard to the carbonic acid. It is therefore the semi- 
 fluid blood-globules which retain these two gases in solution ; and 
 since the color of the blood depends entirely upon that of the glo- 
 bules, it is easy to understand why the blood should alter its hue 
 from purple to scarlet in passing through the lungs, where the 
 globules give up carbonic acid, and absorb a fresh quantity of 
 oxygen. The above change may readily be produced outside the 
 body. If freshly drawn venous blood be shaken in a bottle with, 
 pure oxygen, its color changes at once from purple to red ; and the 
 same change will take place, though more slowly, if the blood be 
 simply agitated with atmospheric air. It is for this reason that the 
 surface of defibrinated venous blood, and the external parts of a 
 dark-colored clot, exposed to the atmosphere, become rapidly red- 
 dened, while the internal portions retain their original color. 
 
 The process of respiration, so far as we have considered it, con- 
 sists in an alternate interchange of carbonic acid and oxygen in the 
 blood of the general and pulmonary circulations. In the pulmonary 
 circulation, carbonic acid is given off and oxygen absorbed ; while 
 
 ' Op. cit., vol. i. p. 393. 
 
 2 In Robin and Verdeil, op. cit., vol. ii. pp. 28—32. 
 
CHANGES OF THE BLOOD DURING RESPIRATION. 211 
 
 in the general circulation tlie oxygen gradually disappears, and is 
 replaced, in the venous blood, by carbonic acid. The oxygen' which 
 thus disappears from the blood in the general circulation does not, 
 for the most part, enter into direct combination in the blood itself. 
 On the contrary, it exists there, as we have already stated, in the 
 form of a simple solution. It is absorbed, however, from the blood 
 of the capillary vessels, and becomes fixed in the substance of the 
 vascular tissues. The blood may be regarded, therefore, in this 
 respect, as a circulating fluid, destined to transport oxygen from the 
 lungs to the tissues ; for it is the tissues themselves which finally 
 appropriate the oxygen, and fix it in their substance. 
 
 The next important question which presents itself in the study 
 of the respiratory process relates to the origin of the carbonic acid in 
 the venous blood. It was formerly supposed, when Lavoisier first 
 discovered the changes produced in the air by respiration, that the 
 production of the carbonic acid could be accounted for in a very 
 simple manner. It was thought to be produced in the lungs by a 
 direct union of the inspired oxygen with the carbon of the blood 
 in the pulmonary vessels. It was found afterward, however, that 
 this could not be the case; since carbonic acid exists already formed 
 in the blood, previous to its entrance into the lungs. It was then 
 imagined that the oxidation of carbon, and the consequent produc- 
 tion of carbonic acid, took place in the capillaries of the general 
 circulation, since it could not be shown to take place in the lungs, 
 nor between the lungs and the capillaries. The truth is, however, 
 that no direct evidence exists of such a direct oxidation taking 
 place anywhere. The formation of carbonic acid, as it is now 
 understood, takes place in three different modes: 1st, in the lungs; 
 2d, in the blood; and 3d, in the tissues. 
 
 First, in the lungs. There exists in the pulmonary tissue a pecu- 
 liar acid substance first described by Yerdeil' under the name of 
 " pneumic" or "pulmonic" acid. It is a crystallizable body, soluble 
 in water, which is produced in the substance of the pulmonary 
 tissue by transformation of some of its other ingredients, in the 
 same manner as sugar is produced in the tissue of the liver. It is 
 on account of the presence of this substance that the fresh tissue of 
 the lung has usually an acid reaction to test-paper, and that it has 
 also the property, which has been noticed by several observers, of 
 
 ' Robin and Verdeil, op. cit., vol. ii. p. 460. 
 
212 EESPIRATION. 
 
 decomposing the metallic cyanides, with the production of hydro- 
 cyanic acid ; a property not possessed by sections of areolar tissue, 
 the internal surface of the skin, &c. &c. When the blood, there- 
 fore, comes in contact with the pulmonary tissue, which is 
 permeated everywhere by pneumic acid in a soluble form, its 
 alkaline carbonates and bicarbonates, if any be present, are decom- 
 posed with the production on the one hand of the pneumates of 
 soda and potass, and on the other of free carbonic acid, which is 
 exhaled, M, Bernard has found^ that if a solution of bicarbonate 
 of soda be rapidly injected into the jugular vein of a rabbit, it 
 becomes decomposed in the lungs with so rapid a development of 
 carbonic acid, that the gas accumulates in the pulmonary tissue, 
 and even in the pulmonary vessels and the cavities of the heart, to 
 such an extent as to cause immediate death by stoppage of the 
 circulation. In the normal condition, however, the carbonates and 
 bicarbonates of the blood arrive so slowly at the lungs that as fast 
 as they are decomposed there, the carbonic acid is readily exhaled 
 by expiration, and produces no deleterious efiect on the circulation. 
 
 Secondly, in the blood. There is little doubt, although the fact has 
 not been directly proved, that some of the oxygen definitely dis- 
 appears, and some of the carbonic acid is also formed, in the sub- 
 stance of the blood-globules during their circulation. Since these 
 globules are anatomical elements, and since they undoubtedly go 
 through with nutritive processes analogous to those which take 
 place in the elements of the solid tissues, there is no reason for dis- 
 believing that they also require oxygen for their support, and that 
 they produce carbonic acid as one of the results of their interstitial 
 decomposition. While the oxygen and carbonic acid, therefore, 
 contained in the globule^, are for the most part transported by 
 these bodies from the lungs to the tissues, and from the tissues back 
 again to the lungs, they probably take part, also, to a certain extent, 
 in the nutrition of the blood-globules themselves. 
 
 Thirdly, in the tissues. This is by far the most important source 
 of the carbonic acid in the blood. From the experiments of Spal- 
 lanzani, W, Edwards, Marchand and others, the following very 
 important fact has been established, viz., that every organized tissue 
 and even every organic substance, when in a recent condition, has the 
 power of absorbing oxygen and of exhaling carbonic acid. G, Liebig, 
 for example,^ found that frog's muscles, recently prepared and com- 
 
 ' Archives Gen. de Med,, xvi, 222. ^ In Lehmann, op. cit., vol. ii. p. 474. 
 
CHANGES OF THE BLOOD DURING RESPIRATION. 213 
 
 pletely freed from blood, continued to absorb oxygen and discharge 
 carbonic acid. Similar experiments with other tissues have led 
 to a similar result. The interchange of gases, therefore, in the 
 process of respiration, takes place mostly in the tissues themselves. 
 It is in their substance that the oxygen becomes fixed and assimi- 
 lated, and that the carbonic acid takes its origin. As the blood in 
 the lungs gives up its carbonic acid to the air, and absorbs oxygen 
 from it, so in the general circulation it gives up its oxygen to the 
 tissues, and absorbs from them carbonic acid. 
 
 We come lastly to examine the exact mode by which the car- 
 bonic acid originates in the animal tissues. Investigation shows that 
 even here it is not produced hy a process of oxidation, or direct union 
 of oxygen ivith the carbon of the tissues, hut in some other and more 
 indirect mode. This is proved by the fact that animals and fresh 
 animal tissues will continue to exhale carbonic acid in an atmo- 
 sphere of hydrogen or of nitrogen, or even when placed in a vacuum. 
 Marchand found* that frogs would live for from half an hour to an 
 hour in pure hydrogen gas ; and that during this time they exhaled 
 even more carbonic acid than in atmospheric air, owing probably 
 to the superior displacing power of hydrogen for carbonic acid. 
 For while 15,500 grains' weight of frogs exhaled about 1.13 grain 
 of carbonic acid per hour in atmospheric air, they exhaled during 
 the same time in pure hydrogen as much as 4.07 grains. The same 
 observer found that frogs would recover on the admission of air 
 after remaining for nearly half an hour in a nearly complete 
 vacuum ; and that if they were killed by total abstraction of the 
 air, 15,500 grains weight of the animals were found to have 
 eliminated 9.3 grains of carbonic acid. The exhalation of carbonic 
 acid by the tissues does not, therefore, depend directly upon the 
 access of free oxygen. It cannot go on, it is true, for an indefinite 
 time, any more than the other vital processes, without the presence 
 of oxygen. But it may continue long enough to show that the 
 carbonic acid exhaled is not a direct product of oxidation, but that 
 it originates, on the contrary, in all probability, by a decomposi- 
 tion of the organic ingredients of the tissues, resulting in the "pro- 
 duction of carbonic acid on the one hand, and of various other 
 substances on the other, with which we are not yet fully acquainted; 
 in very much the same manner as the decomposition of sugar 
 during fermentation gives rise to alcohol on the one hand and to 
 
 ' Lehmann, op. cit., vol. ii. p. 442. 
 
214 
 
 KESPIRATION. 
 
 carbonic acid on the other. The fermentation of sugar, when it has 
 once commenced, does not require the continued access of air. It 
 will go on in an atmosphere of hydrogen, or even when confined in 
 a close vessel over mercury; since its carbonic acid is not produced 
 by direct oxidation, but by a decomposition of the sugar already 
 present. For the same reason, carbonic acid will continue to be 
 exhaled by living or recently dead animal tissues, even in an atmo- 
 sphere of hydrogen, or in a vacuum. 
 
 Carbonic acid makes its appearance, accordingly, in the tissues, 
 as one product of their decomposition in the nutritive process. 
 From them it is taken up by the blood, either in simple solution or 
 in loose combination as a bicarbonate, transported by the circulation 
 to the lungs, and finally exhaled from the pulmonary mucous mem- 
 brane in a gaseous form. 
 
 • The carbonic acid exhaled from the lungs should accordingly be 
 studied by itself as one of the products of the animal organism, and 
 its quantity ascertained in the different physiological conditions of 
 the body. According to the researches of Vierordt,^ which are 
 regarded as the most accurate on this subject, an adult man gives 
 off 1.62 cubic inch of carbonic acid with each normal expiration. 
 This would give 19.16 cubic inches per minute, 1149.6 cubic inches 
 per hour, and 15.4 cubic feet per day. The amount of carbonic 
 acid exhaled, however, varies from time to time, according to many 
 different circumstances; so that no such estimate can represent 
 correctly its quantity at all times. These variations have been 
 very fully investigated by Andral and Gavarret,^ who found that 
 the principal conditions modifying the amount of this gas produced 
 were age, sex, constitution and development. The variations were 
 very marked in different individuals, notwithstanding that the 
 experiments were made at the same period of the day, and with the 
 subject as nearly as possible in the same condition. Thus they 
 found that the quantity of carbonic acid exhaled per hour in five 
 different individuals was as follows :— 
 
 
 Quantity of Carbonic Acid pek houb 
 
 . 
 
 
 In subjec 
 
 t No. 1 1207 
 
 cubic 
 
 inches 
 
 (( (I 
 
 "2 970 
 
 11 
 
 " 
 
 11 li 
 
 "3 . . . . . 1250 
 
 11 
 
 11 
 
 a u 
 
 "4 . . ". . . 1250 
 
 11 
 
 11 
 
 (1 (f 
 
 "5 1591 
 
 11 
 
 « 
 
 ' In Lehmann, op. cit., vol. ii. p. 439. 
 
 ^ Annales de Cliimie et de Pharmacie, 1843, vol. viii. p. 129. 
 
CHANGES OF THE BLOOD DUKING RESPIRATION. 215 
 
 With regard to the difference produced by age, it was found that 
 from the period of eight years up to puberty the quantity of car- 
 bonic acid increases constantly with the age. Thus a boy of eight 
 years exhales, on the average, 564 cubic inches per hour ; while a 
 boy of fifteen years exhales 981 cubic inches in the same time. 
 Boys exhale during this period more carbonic acid than girls of the 
 same age. In males this augmentation of the quantity of carbonic 
 acid continues till the twenty-fifth or thirtieth year, when it reaches, 
 on the average, 1398 cubic inches per hour. Its quantity then 
 remains stationary for ten or fifteen years ; then diminishes slightly 
 from the fortieth to the sixtieth year; and after sixty years dimi- 
 nishes in a marked degree, so that it may fall so low as 1038 cubic 
 inches. In one superannuated person, 102 years of age, Andral 
 and Gavarret found the hourly quantity of carbonic acid to be 
 only 665 cubic inches. 
 
 In women, the increase of carbonic acid ceases at the period of 
 puberty; and its production then remains constant until the cessa- 
 tion of menstruation, about the fortieth or forty -fifth year. At that 
 time it increases again until after fifty years, when it subsequently 
 diminishes v^ith the approach of old age, as in men. Pregnancy, 
 occurring at any time in the above period, imm.ediately produces a 
 temporary increase in the quantity of carbonic acid. 
 
 The strength of the constitution, and more particularly the deve- 
 lopment of the muscular system, was found to have a very great 
 influence in this respect ; increasing the quantity of carbonic acid 
 very much, in proportion to the weight of the individual. The 
 largest production of carbonic acid observed was in a young man, 
 26 years of age, whose frame presented a remarkably vigorous and 
 athletic development, and who exhaled 1591 cubic inches per hour. 
 This large quantity of carbonic acid, moreover, in well developed 
 persons, is not owing simply to the size of the entire body, but 
 particularly to the development of the muscular system, since an 
 unusually large skeleton, or an abundant deposit of adipose tissue, 
 is not accompanied by any such increase of the carbonic acid. 
 
 Andral and Gavarret finally sum up the results of their investiga- 
 tions as follows : — 
 
 1. The quantity of carbonic acid exhaled from the lungs in a 
 given time varies with the age, the sex, and the constitution of the 
 subject. 
 
 2. In the male, as well as in the female, the quantity of carbonic 
 
216 RESPIRATION. 
 
 acid varies according to the age; and that independently of the 
 weight of the individual subjected to experiment. 
 
 3. During all the periods of life, from that of eight years up to 
 the most advanced age, the male and female may be distinguished 
 by the different quantities of carbonic acid which they exhale in a 
 given time. Other things being equal, the male exhales always a 
 larger quantity than the female. This difference is particularly 
 marked between the ages of 16 and 40 years, during which period 
 the male usually exhales twice as much carbonic acid as the female. 
 
 4. In the male, the quantity of carbonic acid increases constantly 
 from eight to thirty years ; and the rate of this increase undergoes 
 a rapid augmentation at the period of puberty. Beyond thirty 
 years the exhalation of carbonic acid begins to decrease, and its 
 diminution is more marked as the individual approaches extreme 
 old age ; so that near the termination of life, the quantity of carbonic 
 acid produced may be no greater than at the age of ten years. 
 
 5. In the female, the exhalation of carbonic acid increases accord- 
 ing to the same law as in the male, from the age of eight years 
 until puberty. But at the period of puberty, at the same time 
 with the appearance of menstruation, the exhalation of carbonic 
 acid, contrary to what happens in the male, ceases to increase ; and 
 it afterward remains stationary so long as the menstrual periods 
 recur with regularity. At the cessation of the menses, the quantity 
 of carbonic acid exhaled increases in a notable manner ; then it de- 
 creases again, as in the male, as the woman advances toward old age. 
 
 6. During the whole period of pregnancy, the exhalation of car- 
 bonic acid rises, for the time, to the same standard as in women 
 whose menses have ceased. 
 
 7. In both sexes, and at all ages, the quantity of carbonic acid is 
 greater as the constitution is stronger, and the muscular systeni 
 more fully developed. 
 
 Prof. Scharling, in a similar series of investigations,' found that 
 the quantity of carbonic acid exhaled was greater during the diges- 
 tion of food than in the fasting condition. It is greater, also, in the 
 waking state than during sleep ; and in a state of activity than in. 
 one of quietude. It is diminished, also, by fatigue, and by most 
 conditions which interfere with perfect health. 
 
 The process of respiration is not altogether confined to the lungs, 
 
 ' Annales de Chimie et de Pharmacie, vol. viii. p. 490. 
 
CHANGES OF THE BLOOD DURING RESPIRATION. 217 
 
 but the interchange of gases takes place, also, to some extent through 
 the skin. It has been found, by inclosing one of the limbs in an 
 air-tight case, that the air in which it is confined loses oxygen and 
 gains in carbonic acid. By an experiment of this sort, performed by 
 Prof Scharling,^ it was ascertained that the carbonic acid given off 
 from the whole cutaneous surface, in the human subject, is from one- 
 sixtieth to one-thirtieth of that discharged during the same period 
 from the lungs. In the true amphibious animals, that is, those 
 which breathe by lungs, and can yet remain under water for an 
 indefinite period without injury (as frogs and salamanders), the 
 respiratory function of the skin is very active. In these animals, 
 the integument is very vascular, moist, and flexible; and is covered, 
 not with dry cuticle, but with a very thin and delicate layer of 
 epithelium. It, therefore, presents all the conditions necessary for 
 the accomplishment of respiration; and while the animal remains 
 beneath the surface, and the lungs are in a state of inactivity, the 
 exhalation and absorption of gases continue to take place through 
 the skin, and the process of respiration goes on in a nearly unin- 
 terrupted manner. 
 
 ' In Carpenter's Human Physiology, Philada. ed., 1855, p 308. 
 
218 ANIMAL HEAT. 
 
 CHAPTER XIII. 
 
 ANIMAL HEAT. 
 
 One of the most important phenomena presented by animals and 
 vegetables is the property which they possess of maintaining, more 
 or less constantly, a standard temperature, notwithstanding the 
 external vicissitudes of heat and cold to which they may be sub- 
 jected. If a bar of iron, or a jar of water, be heated up to 100° 
 or 200° F., and then exposed to the air at 50° or 60°, it will imme- 
 diately begin to lose heat by radiation and conduction ; and this 
 loss of heat will steadily continue, until, after a certain time, the 
 temperature of the heated body has become reduced to that of the 
 surrounding atmosphere. It then remains stationary at this point, 
 unless the temperature of the atmosphere should happen to rise or 
 fall ; in which case, a similar change takes place in the inorganic 
 body, its temperature remaining constant, or varying with that of 
 the surrounding medium. 
 
 With living animals, the case is different. If a thermometer be 
 introduced into the stomach of a dog, or placed under the tongue 
 of the human subject, it will indicate a temperature of 100° F., very 
 nearly, whatever may be the condition of the surrounding atmos- 
 phere at the time. This internal temperature is the same in sum- 
 mer and in winter. If the individual upon whom the experiment 
 has been tried be afterward exposed to a cold of zero, or even of 20° 
 or 30° below zero, the thermometer introduced into the interior of 
 the body will still stand at 100° F. As the body, during the whole 
 period of its exposure, must have been losing heat by radiation and 
 conduction, like any inorganic mass, and has, notwithstanding, main- 
 tained a constant temperature, it is plain that a certain amount of 
 heat has been generated in the interior of the body by means of the 
 vital processes, sufficient to compensate for the external loss. The 
 internal heat, so produced, is known by the name of vital or animal 
 heat. 
 
 There are two classes of animals in which the production of vital 
 
ANIMAL HEAT. 219 
 
 beat takes place with such activity that their blood and internal 
 organs are nearly always very much above the external temperature; 
 and which are therefore called "warm-blooded animals." Tliese are 
 mammalia and birds. Among the birds, some species, as the gull, 
 have a temperature as low as 100° F.; but in most of them it is 
 higher, sometimes reaching as high as 110° or 111°. In the mam- 
 malians, to which class man belongs, the animal temperature is never 
 far from 100°. In the seal and the Greenland whale, it has been 
 found to be 10-4°; and in the porpoise, which is an air-breathing 
 animal, 99°.5. In the human subject it is 98° to 100.° When the 
 temperature of the air is below this, the external parts of the body, 
 being most exposed to the cooling influences of radiation and con- 
 duction, fall a little below the standard, and may indicate a tempera- 
 ture of 97°, or even several degrees below this point. Thus, on a 
 very cold day, the thinner and more exposed parts, such as the nose, 
 the ears, and the ends of the fingers, may become cooled down con- 
 siderably below the standard temperature, and may even be con- 
 gealed, if the cold be severe; but the temperature of the internal 
 organs and of the blood still remains the same under all ordinary 
 exposures. 
 
 If the cold be so intense and long continued as to affect the 
 general temperature of the blood, it at once becomes fatal. It has 
 been found that although a warm-blooded animal usually preserves 
 its natural temperature when exposed to external cold, yet if the 
 actual temperature of the blood become reduced by any means 
 more than 5° or 6° below its natural standard, death inevitably 
 results. The animal, under these circumstances, gradually becomes 
 torpid and insensible, and all the vital operations finally cease. 
 Birds, accordingly, whose natural temperature is about 110°, die if 
 the blood be cooled down to 100°, which is the natural temperature 
 of the mammalia ; and the mammalians die if their blood be cooled 
 down below 94° or 95°. Each of these different classes has there- 
 fore a natural temperature, at which the blood must be maintained 
 in order to sustain life; and even the different species of animals, 
 belonging to the same class, have each a specific temperature which 
 is characteristic of them, and which cannot be raised or lowered, to 
 any considerable extent, without producing death. 
 
 While in the birds and mammalians, however, the internal pro- 
 duction of heat is so active, that their temperature is nearly always 
 considerably above that of the surrounding media, and suffers but 
 little variation ; in reptiles and fish, on the other hand, its produc- 
 
220 
 
 ANIMAL HEAT. 
 
 tion is much less rapid, and the temperature of their bodies differs 
 but little from that of the air or water which they inhabit. Birds and 
 mammalians are therefore called " warm-blooded," and reptiles and 
 fish " cold-blooded" animals. There is, however, no other distinc- 
 tion between them, in this respect, than one of degree. In reptiles 
 and fish there is also an internal source of heat ; only this is not so 
 active as in the other classes. Even in these animals a difierence 
 is usually found to exist between the temperature of their bodies 
 and that of the surrounding media. John Hunter, Sir Humphrey 
 Davy, Czermak, and others,' have found the temperature of Proteus 
 anguinus to be 63°.5, when that of the air was 55° A] that of a frog 
 48°, in water at 44°.4 ; that of a serpent 88°.46, in air at 81°.5 ; that 
 of a tortoise 84°, in air at 79°.o ; and that of fish to be from 1°.7 
 to 2°.5 above that of the surrounding water. 
 
 The following list^ shows the mean temperature belongmg to 
 animals of different classes and species. 
 
 Birds. 
 
 Mammalia. ■ 
 
 Reptile. 
 
 Fish. 
 
 { 
 
 Animal. 
 
 Swallow 
 
 Heron 
 
 Raven 
 
 Pigeon 
 
 Fowl 
 ^ Gull 
 
 Squirrel 
 
 Goat 
 
 Cat 
 
 Hare 
 
 Ox 
 
 Dog 
 
 Man 
 L Ape 
 
 Toad 
 
 Carp 
 
 Tench 
 
 Mean Temperatdke. 
 1110.25 
 1110.2 
 108O.5 
 1070.6 
 106O.7 
 1000.0 
 1050 
 1020.5 
 1010.3 
 1000.4 
 
 990,5 
 
 990.4 
 
 980.6 
 
 950.9 
 
 510.6 
 
 510.25 
 520.10 
 
 In the invertebrate animals, as a general rule, the internal heat 
 is produced in too small quantity to be readily estimated. In some 
 of the more active kinds, however, such as insects and arachnida, 
 it is occasionally generated with such activity that it may be 
 appreciated by the thermometer. Thus, the temperature of the 
 butterfly, when in a state of excitement, is from 5° to 9° above 
 
 ' Simon's Chemistry of Man, Philadelphia edition, p. 124. 
 2 Ihid., pp. 123—126. 
 
ANIMAL HEAT. 221 
 
 that of the air ; and that of the humble-bee from 3° to 10° higher 
 than the exterior. According to the experiments of Mr. Newport/ 
 the interior of a hive of bees may have a temperature of 48*^.5, 
 when the external atmosphere is at 34°.5, even while the insects 
 are quiet; but if they be excited, by tapping on the outside of the 
 hive, it may rise to 102°. In all cases, while the insect is at rest, 
 the temperature is very moderate; but if kept in rapid motion in 
 a confined space, it may generate heat enough to affect the thermo- 
 meter sensibly, in the course of a few minutes. 
 
 Even in vegetables a certain degree of heat-producing power is 
 occasionally manifest. Usually, the exposed surface of a plant is 
 so extensive in proportion to its mass, that whatever caloric may 
 be generated is too rapidly lost by radiation and evaporation, to be 
 appreciated by ordinary means. Under some circumstances, how- 
 ever, it may accumulate to such an extent as to become readily 
 perceptible. In the process of malting, for example, when a large 
 quantity of germinating grain is piled together in a mass, its ele- 
 vated temperature may be readily distinguished, both by the hand 
 and the thermometer. During the flowering process, also, an unu- 
 sual evolution of heat takes place in plants. The flowers of the 
 geranium have been found to have a temperature of 87°, while 
 that of the air was 81°; and the thermometer, placed in the centre 
 of a clump of blossoms of arum cordifolium, has been seen to rise 
 to 111°, and even 121°, while the temperature of the external air 
 was only 66°.^ 
 
 Dutroctzet has moreover found, by a series of very ingenious and 
 delicate experiments,^ that nearly all parts of a living plant gene- 
 rate a certain amount of heat. The proper beat of the plant is 
 usually so rapidly dissipated by the continuous evaporation of its 
 fluids, that it is mostly imperceptible by ordinary means ; but if 
 this evaporation be prevented, by keeping the air charged with 
 watery vapor, tbe heat becomes sensible and can be appreciated by 
 a delicate thermometer. Dutrochet used for this purpose a thermo- 
 electric apparatus, so constructed that an elevation of temperature 
 of 1° F., in the substance examined, would produce a deviation in 
 the needle of nearly nine degrees. By this means he found that he 
 could appreciate, without difficulty, the proper temperature of the 
 plant. A certain amount of heat was constantly generated, during 
 
 ' Carpenter's General and Comparative Physiology, Philadelphia, 1851, p, 852, 
 
 * Carpenter's Gen, and Comp. Physiology, p, 846. 
 
 ' Annales des Sciences Naturelles, 2d series, xii, p. 277. 
 
222 ANIMAL HEAT. 
 
 the day, in the green stems, the leaves, the buds, and even the 
 roots and fruit. The maximum temperature of these parts, above 
 that of the surrounding atmosphere, was sometimes a little over 
 one-half a degree, Fahrenheit; though it was often considerably 
 less than this. 
 
 The different parts of the vegetable fabric, therefore, generate 
 different quantities of caloric. In the same manner, the heat-pro- 
 ducing power is not equally active in different species of animals ; 
 but its existence is nevertheless common to both animals and vege- 
 tables. 
 
 With regard to the mode of generation of this internal or vital 
 heat, we may start with the assertion that its production depends 
 upon changes of a chemical nature, and is so far to be regarded as 
 a chemical phenomenon. The sources of heat which we meet with 
 in external nature are of various kinds. Sometimes the heat is of 
 a physical origin ; as, for example, that derived from the rays of 
 the sun, the friction of solid substances, or the passage of electric 
 currents. In other instances it is produced by chemical changes ; 
 and the most abundant and useful source of artificial heat is the 
 oxidation, or combustion, of carbon and carbonaceous compounds. 
 Wood and coal, substances rich in carbon, are mostly used for this 
 purpose ; and charcoal, which is nearly pure carbon, is frequently 
 employed by itself. These substances, when burnt, or oxidized, 
 evolve a large amount of heat ; and produce, as the result of their 
 oxidation, carbonic acid. In order that the process may go on, it 
 is of course necessary that oxygen, or atmospheric air, should have 
 free access to the burning body; otherwise the combustion and 
 evolution of heat cease, for want of a necessary agent in the chemi- 
 cal combination. In all these instances, the quantity of heat gene- 
 rated is in direct proportion to the amount of oxidation ; and may 
 be measured, either by the quantity of carbon consumed, or by that 
 of carbonic acid produced. It may be made to go on, also, either 
 rapidly or slowly, according to the abundance and purity in which 
 oxygen is supplied to the carbonaceous substance. Thus, if char- 
 coal be ignited in an atmosphere of pure oxygen, it burns rapidly 
 and violently, raises the temperature to a high point, and is soon 
 entirely consumed. On the other hand, if it be shut up in a close 
 stove, to which the air is admitted but slowly, it produces only a 
 slight elevation of temperature, and may require a much longer 
 time for its complete disappearance. Nevertheless, for the same 
 quantity of carbon consumed, the amount of heat generated, and 
 
ANIMAL HEAT. 223 
 
 that of carbonic acid produced, will be equal in the two cases. In 
 one instance we have a rapid combustion, in the other a slow com- 
 bustion ; the total effect being, however, the same in both. 
 
 Such is the mode in which heat is commonly produced by artifi- 
 cial means. Its evolution is here dependent upon two striking 
 conditions, which are essential to it, and by which it is always 
 accompanied, viz., the consumption of oxygen, and the production 
 of carbonic acid. 
 
 Now, since the two phenomena just mentioned are presented 
 also by the living body, and since they are accompanied here, too, 
 by the production of animal heat, it was very natural to suppose 
 that in the animal organization, as well as elsewhere, the internal 
 heat must be owing to an oxidation or combustion of carbon. 
 According to Lavoisier, the oxygen taken into the lungs was sup- 
 posed to combine immediately with the carbon of the pulmonary 
 tissues and fluids, producing carbonic acid, and to be at once returned 
 under that form to the atmosphere; the same quantity of heat result- 
 ing from the above process as would have been produced by the 
 oxidation of a similar quantity of carbon in wood or coal. Accord- 
 ingly, he regarded the lungs as a sort of stove or furnace, by which 
 the rest of the body was warmed, through the medium of the circu- 
 lating blood. 
 
 It was soon found, however, that this view was altogether erro- 
 neous ; for the slightest examination shows that the lungs are not 
 perceptibly warmer than the rest of the body ; and that the heat- 
 producing power, whatever it may be, does not reside exclusively 
 in the pulmonary tissue. Furthermore, subsequent investigations 
 showed the following very important facts, which we have already 
 mentioned, viz., that the carbonic acid is not formed in the lungs, 
 but exists in the blood before its arrival in the pulmonary capilla- 
 ries ; and that the oxygen of the inspired air, so far from combining 
 with carbon in the lungs, is taken up in solution by the blood- 
 globules, and carried away by the current of the general circulation. 
 It is evident, therefore, that this oxidation or combustion of the 
 blood must take place, if at all, not in the lungs, but in the capil- 
 laries of the various organs and tissues of the body. 
 
 Liebig accordingly adopted Lavoisier's theory of the production 
 of animal heat, with the above modification. He believed the heat 
 of the animal body to be produced by the oxidation or combustion 
 of certain elements of the food while still circulating in the blood ; 
 these substances being converted into carbonic acid and water by 
 
224 ANIMAL HEAT. 
 
 the oxidation of their carbon and hydrogen, and immediately ex- 
 pelled from the body without ever having formed a part of the solid 
 tissues. He therefore divided the food into two different classes of 
 alimentary substances; viz., 1st, the nitrogenous or plastic elements^ 
 which are introduced in comparatively small quantity, and which 
 are to be actually converted into the substance of the tissues, such as 
 albumen, muscular flesh, &c. ; and 2d, the hydro-carhons or respiratory 
 elements, such as sugar, starch, and fat; which, according to his view, 
 are taken into the blood solely to be burned, never being assimilated 
 or converted into the tissues, but only oxidized in the circulation, 
 and immediately expelled, as above, under the form of carbonic 
 acid and water. He therefore regardf^d these elements of the food 
 only as so much fuel ; destined simply to maintain the heat of the 
 body, but taking no part in the proper function of nutrition. 
 
 The above theory of animal heat has been very generally adopted 
 and acknowledged by the medical profession until within a recent 
 period. A few years ago, however, some of its deficiencies and 
 inconsistencies were pointed out, by Lehmann in Germany, and by 
 Eobin and Verdeil in France ; and since that time it has begun to 
 lose ground and give place to a different mode of explanation, more 
 in accordance with the present state of physiological science. We 
 believe it, in fact, to be altogether erroneous; and incapable of 
 explaining, in a satisfactory manner, the phenomena of animal heat, 
 as exhibited by the living body. We shall now proceed to pass in 
 review the principal objections to the theory of combustion, con- 
 sidered as a physiological doctrine. 
 
 I. It is not at all necessary to regard the evolution of heat as 
 dependent solely on direct oxidation. This is only one of its 
 sources, as we see constantly in external nature. The sun's rays, 
 mechanical friction, electric currents, and more particularly a great 
 variety of chemical actions, such as various saline combinations and 
 decompositions, are all capable of producing heat ; and even simple 
 solutions, such as the solution of caustic potass in water, the mixture 
 of sulphuric acid and water, or of alcohol and water, will often pro- 
 duce a very sensible elevation of temperature. Now we know that 
 in the interior of the body a thousand different actions of this 
 nature are constantly going on; solutions, combinations and decom- 
 positions in endless variety, all of which, taken together, are amply 
 sufficient to account for the production of animal heat, provided the 
 theory of combustion should be found insufficient or improbable. 
 
ANIMAL HEAT. 225 
 
 II. In vegetables there is an internal production of heat, as well 
 as in animals; a fact which has been fully demonstrated by the 
 experiments of Dutrochet and. others, already described. In vege- 
 tables, however, the absorption of oxygen and exhalation of car- 
 bonic acid do not take place; excepting, to some extent, during the 
 night. On the contrary, the diurnal process in vegetables, it is well 
 known, is exactly the reverse of this. Under the influence of the 
 solar light they absorb carbonic acid and exhale oxygen. And it 
 is exceedingly remarkable that, in Dutrochet's experiments, he 
 found that the evolution of heat by plants was always accompanied 
 by the disappearance of carbonic acid and the exhalation of oxygen. 
 Plants which, in the daylight, exhale oxygen and evolve heat, if 
 placed in the dark, immediately begin to absorb oxygen and exhale 
 carbonic acid ; and, at the same time, tbe evolution of heat is sus- 
 pended. Dutrochet even found that the evolution of heat by plants 
 presented a regular diurnal variation; and that its maximum of 
 intensity was aboilt the middle of the day, just at the time when the 
 absorption of carbonic acid and the exhalation of oxygen are going on 
 with the greatest activity. The proper heat of plants, therefore, can- 
 not be the result of oxidation or combustion, but must be dependent 
 on an entirely different process. 
 
 * 
 
 III. In animals, the quantities of oxygen absorbed and of 
 carbonic acid exhaled do not correspond with each other. Most 
 frequently a certain amount of oxygen disappears in the body, over 
 and above that which is returned in the breath under the form of 
 carbonic acid. This overplus of oxygen has been said to unite with 
 the hydrogen of the food, so as to form water which also passes out 
 by the lungs ; but this is a pure assumption, resting on no direct 
 evidence whatever, for we have no experimental proof that any 
 more watery vapor is exhaled from the lungs than is supplied by 
 the fluids taken into the stomach. It is superfluous, therefore, to 
 assume that any of it is produced by the oxidation of hydrogen. 
 
 Furthermore, the proportion of overplus oxygen which disap- 
 pears in the body, beside that which is exhaled in the carbonic acid 
 of the breath, varies greatly in the same animal according to the 
 quality of the food. Eegnault and Eeiset' found that in dogs, fed 
 on meat, the oxygen which reappeared under the form of carbonic 
 acid was only 75 per cent, of the whole quantity absorbed ; while 
 
 ' Aiinales de Chiiiiie et de Physique, 3d series, xxvi. p. 428. 
 15 
 
226 AXIMAL HEAT. 
 
 in dogs fed on vegetable substances it amounted to over 90 per 
 cent. In some instances/ where the animals (rabbits and fowls) 
 were fed on bread and grain exclusively, the proportion of expired 
 oxygen amounted to 101 or even 102 per cent.; that is, more oxygen 
 luas actually contaiyied in the carbonic acid exhaled, than had been ab- 
 sorbed in a free state from the atmosphere. A portion, at least, of the 
 carbonic acid must therefore have been produced by other means 
 than direct oxidation. 
 
 TV. It has already been shown, in a previous chapter, that the 
 carbonic acid which is exhaled from the lungs is not primarily 
 formed in the blood, but makes its appearance in the substance of 
 the tissues themselves ; and furthermore, that even here it does not 
 originate by a direct oxidation, but rather by a process of decom- 
 position, similar to that by which sugar, in fermentation, is resolved 
 into alcohol and carbonic acid. We understand from this how to 
 explain the singular fact alluded to in the last paragraph, viz., the 
 abundant production of carbonic acid, under some circumstances, 
 with a comparatively small supply of free oxygen. The statement 
 made by Liebig, therefore, that starchy and oily matters taken with 
 the food are immediately oxidized in the circulation without ever 
 being assimilated by the tissues, is without foundation. It never, 
 in fact, rested on any other ground than a supposed probability; 
 and as we see that carbonic acid is abundantly produced in the 
 body by other means, we have no longer any reason for assuming, 
 without direct evidence, the existence of a combustive process in 
 the blood. 
 
 V. The evolution of heat in the animal body is not general, as it 
 would be if it resulted from a combustion of the blood ; but local, 
 since it takes place primarily in the substance of the tissues them- 
 selves. Various causes will therefore produce a local elevation or 
 depression of temperature, by modifying the nutritive changes 
 which take place in the tissues. Thus, in the celebrated experiment 
 of Bernard, which we have often verified, division of the sympa- 
 thetic nerve in the middle of the neck produces very soon a marked 
 elevation of temperature in the corresponding side of the head and 
 face. Local inflammations, also, increase very sensibly the tempera- 
 ture of the part in which they are seated, while that of the general 
 
 ' Annales de Chimie et de Physique, 3d series, xxvi. pp. 409 — 451. 
 
ANIMAL HEAT. 227 
 
 mass of the blood is not altered. Finally it has been demonstrated 
 by Bernard that in the natural state of the system there is a marked 
 difference in the temperature of the dififerent organs and of the blood 
 returning from them.* The method adopted by this experimenter 
 was to introduce, in the living animal, the bulb of a fine thermo- 
 meter successively into the bloodvessels entering and those leaving 
 the various internal organs. The difference of temperature in these 
 two situations showed whether the blood had lost or gained in heat 
 Avhile traversing the capillaries of the organ. Bernard found, in 
 the first place, that the blood in passing through the lungs, so far 
 from increasing, was absolutely diminished in temperature; the 
 blood on the left side of the heart being sometimes a little more 
 and sometimes a little less than one-third of a degree Fahr. lower 
 than on the right side. This slight cooling of the blood in the 
 lungs is owing simply to its exposure to the air through the pul- 
 monary membrane, and to the vaporization of water which takes 
 place in these organs. In the abdominal viscera, on the contrary, 
 the blood is increased in temperature. It is sensibly warmer in the 
 portal vein than in the aorta ; and very considerably warmer in the 
 hepatic vein than in either the portal or the vena cava. The blood 
 of the hepatic vein is in fact warmer than that of any other part 
 of the body. The production of heat, therefore, according to Ber- 
 nard's observations, is more active in the liver than in any other 
 portion of the system. As the chemical processes of nutrition are 
 necessarily different in the different tissues and organs, it is easy to 
 understand why a specific amount of heat should be produced in 
 each of them. A similar fact, it will be recollected, was noticed by 
 Dutrochet, in regard to the different parts of the vegetable organ- 
 ization. 
 
 VI. Animal heat has been supposed to stand in a special relation 
 to the production of carbonic acid, because in warm-blooded animals 
 the respiratory process is more active than in those of a lower 
 temperature; and because, in the same animal, an increase or 
 diminution in the evolution of heat is accompanied by a corre- 
 sponding increase or diminution in the products of respiration. 
 But this is also true of all the other excretory products of the body. 
 An elevation of temperature is accompanied by an increased activity 
 of all the nutritive processes. Not only carbonic acid, but the 
 
 ' Gazette Hebdomadaiie, Aug. 29 and Sept. 26, 1856. 
 
228 ANIMAL HEAT. 
 
 ingredients of the urine and the perspiration are discharged in larger 
 quantity than usual. An increased supply of food also is required, 
 as well as a larger quantity of oxygen; and the digestive and 
 secretory processes both go on, at the same time, with unusual 
 activity. 
 
 Animal heat, then, is a phenomenon which results from the 
 simultaneous activity of many different processes, taking place in 
 many different organs, and dependent, undoubtedly, on different 
 chemical changes in each one. The introduction of oxygen and 
 the exhalation of carbonic acid have no direct connection with each 
 other, but are only the beginning and the end of a long series of 
 continuous changes, in which all the tissues of the body successively 
 take a part. Their relation is precisely that which exists between 
 the food introduced through the stomach, and the urinary ingre- 
 dients eliminated by the kidneys. The tissues require for their 
 nutrition a constant supply of solid and liquid food which is intro- 
 duced through the stomach, and of oxygen which is introduced 
 through the lungs. The disintegration and decomposition of the 
 tissues give rise, on the one hand, to urea, uric acid, &c., which are 
 discharged with the urine, and on the other hand to carbonic acid, 
 which is exhaled from the lungs. But the oxygen is not directly 
 converted into carbonic acid, any more than the food is directly 
 converted into urea and the urates. 
 
 Animal heat is not to be regarded, therefore, as the result of a 
 combustive process. There is no reason for believing that the 
 greater part of the food is " burned" in the circulation. It is, on 
 the contrary, assimilated by the substance of the tissues; and these, 
 in their subsequent disintegration, give rise to several excretory 
 products, one of which is carbonic acid. 
 
 The numerous combinations and decompositions which follow 
 each other incessantly during the nutritive process, result in the 
 production of an internal or vital heat, which is present in both 
 animals and vegetables, and which varies in amount in different 
 species, in the same individual at different times, and even in 
 different parts and organs of the same body. 
 
THE CIRCULATION". 229 
 
 CHAPTER XIV. 
 
 THE CIRCULATION. 
 
 The blood may be regarded as a nutritious fluid, holding in 
 solution all the ingredients necessary for the formation of the 
 tissues. In some animals and vegetables, of the lowest organization, 
 such as infusoria, polypes, algte, and the like, neither blood nor 
 circulation is required ; since all parts of the body, having a similar 
 structure, absorb nourishment equally from the surrounding media, 
 and carry on nearly or quite the same chemical processes of growth 
 and assimilation. In the higher animals and vegetables, however, 
 as well as in the human subject, the case is different. In them, the 
 structure of the body is compound. Different organs, with widely 
 different functions, are situated in different parts of the frame ; and 
 each of these functions is more or less essential to the continued 
 existence of the whole. In the intestine, for example, the process 
 of digestion takes place ; and the prepared ingredients of the food 
 are thence absorbed into the bloodvessels, by which they are 
 transported to distant tissues and organs. In the lungs, again, 
 the blood absorbs oxygen which is afterward to be appropriated by 
 the tissues; and carbonic acid, which was produced in the tissues, 
 is exhaled from the lungs. In the liver, the kidneys, and the skin, 
 other substances again are produced or eliminated, and these local 
 processes are all of them necessary to the preservation of the general 
 organization. The circulating fluid is therefore, in the higher 
 animals, a means of transportation, by which the substances pror 
 duced in particular organs are dispersed throughout the body, or 
 by which substances produced generally in the tissues are conveyed 
 to particular organs, in order to be eliminated and expelled. 
 
 The circulatory apparatus consists of four different parts, viz: 
 1st. The heart ; a hollow, muscular organ, which receives the blood 
 at one orifice and drives it out, in successive impulses, at another. 
 2d. The arteries ; a series of branching tubes, which convey the 
 blood from the heart to the different tissues and organs of the body. 
 
230 
 
 THE CIRCULATION'. 
 
 3d. The capillaries; a network of minute inosculating tubules, 
 whicli are interwoven with the substance of the tissues, and which 
 bring the blood into intimate contact with the cells and fibres of 
 which thej are composed; and, 4th. The veins; a set of converg- 
 ing vessels, destined to collect the blood from the capillaries, and 
 return it to the heart. In each of these four different parts of the 
 circulatory apparatus, the movement of the blood is peculiar and 
 dependent on special conditions. It will therefore require to be 
 studied in each one of them separately. 
 
 THE HEART. 
 
 The structure of the heart, and of the large vessels connected 
 with it, varies considerably in different classes of animals, owing to 
 the different arrangement of the respiratory organs. For the respi- 
 ratory apparatus being one of the most important in the body, and 
 
 the one most closely connected 
 •^'S* '^^' by anatomical relations with 
 
 the organs of circulation, the 
 latter are necessarily modified 
 in structure to correspond with 
 the former. In fish, for exam- 
 ple (Fig. 76), the heart is an 
 organ consisting of two princi- 
 pal cavities : an auricle (a) into 
 which the blood is received from 
 the central extremity of the 
 vena cava, and a ventricle (b) 
 into which the blood is driven 
 by the contraction of the auricle. 
 The ventricle is considerably 
 larger and more powerful than 
 the auricle, and by its contrac- 
 tion drives the blood into the 
 main artery supplying the gills. 
 In the gills (cc) the blood is 
 arterialized ; after which it is 
 collected by the branchial veins. 
 These veins unite upon the median line to form the aorta {d) by 
 which the blood is finally distributed throughout the frame. In 
 
 Circulation- of Fish. — a. Auricle, b. 
 Ventricle, cc. Gills, d. Aorta, ee. Vense carse. 
 
THE HEART. 
 
 231 
 
 Fig. 77. 
 
 these animals the respiratory process is not a very active one; but 
 the gills, which are of small size, being the only respiratory organs, 
 all the blood requires to pass through them for purposes of aeration. 
 The heart here is a single organ, destined only to drive the blood 
 from the termination of the venous system to the capillaries of the 
 gills. 
 
 In reptiles, the heart is composed of two auricles, placed side by 
 side, and one ventricle. (B'ig. 77.) The venas cavas discharge their 
 blood into the right auricle (a), 
 whence it passes into the ventricle 
 (c). From the ventricle, a part of it 
 is carried into the aorta and distri- 
 buted throughout the body, while a 
 part is sent to the lungs through the 
 pulmonary artery. The arterialized 
 blood, returning from the lungs by 
 the pulmonary vein, is discharged 
 into the left auricle (6), and thence 
 into the ventricle (c), where it 
 mingles with the venous blood 
 which has just arrived by the venae 
 cavae. In the reptile, therefore, the 
 ventricle is a common organ of pro- 
 pulsion, both for the lungs and for 
 the general circulation. In these 
 animals the aeration of the blood in 
 the lungs is only partial ; a certain 
 portion of the blood which leaves 
 the heart being carried to these organs, just as in the human subject, 
 it is only a portion of the blood which is carried to the kidney by 
 the renal artery. This arrangement is sufficient for the reptiles, 
 because in many of them, such as serpents and turtles, the lungs 
 are much more extensive and efficient, as respiratory organs, than 
 the gills of fish ; while in others, such as frogs and water-lizards, 
 the integument itself, which is moist, smooth, and naked, takes an 
 important share in the aeration of the blood. 
 
 In quadrupeds and the human species, however, 'the respi- 
 ratory process is not only exceedingly active, but the lungs 
 are, at the same time, the only organs in which the aeration of 
 the blood can be fully accomplished. In them, accordingly, we 
 find the two circulations, general and pulmonary, entirely dis- 
 
 ClRCITLATIOX OF REPTILES. — a. 
 
 Right auricle. 6. Left auricle, c. Ventricle. 
 d. Lungs, e. Aorta, f. Vena Cava. 
 
232 
 
 THE CIRCULATION. 
 
 tinct from each other. (Fig. 78.) All the blood returning from 
 the body by the veins must pass through the lungs before it is 
 
 again distributed through the 
 Fig- 78. arterial system. We have 
 
 therefore a double circula- 
 tion, and also a double heart ; 
 the two sides of which, 
 though united externally, 
 are separate internally. The 
 mammalian heart consists of 
 a right auricle and ventricle 
 ((7, h), receiving the blood 
 from the vena cava (?"), and 
 driving it to the lungs ; and 
 a left auricle and ventricle 
 (/, g) receiving the blood 
 from the lungs and driving 
 it outward through the arte- 
 rial system. 
 
 In the complete or double 
 mammalian heart, the differ- 
 ent parts of the organ present 
 certain peculiarities and bear 
 certain relations to each other, which it is necessary to understand 
 before we can properly appreciate its action and movements. The 
 entire organ has a more or less conical form, its base being situated 
 on the median line, directed upward and backward ; the whole being 
 suspended in the chest, and loosely fixed to the spinal column, by 
 the great vessels which enter and leave it at this point. The apex, 
 on the contrary, is directed downward, forward, and to the left, sur- 
 rounded by the pericardium and the pericardial fluid, but capable 
 of a very free lateral and rotatory motion. The auricles, which 
 have a smaller capacity and thinner walls^ than the ventricles, are 
 situated at the upper and posterior part of the organ (Figs. 79 and 
 80); while the ventricles occupy its anterior and lower portions. 
 The two ventricles, moreover, are not situated on the same plane, 
 but the right ventricle occupies a position somewhat in front and 
 above that of the left ; so that in an anterior view of the heart the 
 greater portion of the left ventricle is concealed by the right (Fig. 
 79), and in a posterior view the greater portion of the right ven- 
 tricle is concealed by the left (Fig. 80); while in both positions the 
 
 Circulation in Mammalians. — a. Right 
 auricle. 6. Eight ventricle, c. Pulmonary artery. 
 d. Lungs, e. Pulmonary vein. / Left auricle, g. 
 Left ventricle, h. Aorta, i. Vena cava. 
 
THE HEART. 
 
 233 
 
 apex of tlie heart is constituted altogether by the point of the left 
 ventricle. 
 
 Fig. 80. 
 
 Human Heart, anterior view. — 
 a. Right ventricle, b. Left ventricle. 
 c. Right auricle, d. Left auricle, e. 
 Pulmonary artery. /. Aorta. 
 
 Human Heart, posterior view. — 
 a. Right ventricle, b. Left ventricle. 
 c. Right auricle, d. Left auricle. 
 
 The different cavities of the heart and of the adjacent blood- 
 vessels, though continuous with each other, are partially separated 
 by certain constrictions. These constricted orifices, by which the 
 different cavities communicate, are known by the names of the 
 
 Fig, 81. 
 
 RiOHT Auricle and Ventricle; Auriculo-ventricular Valves open. Arterial Valves closed. 
 
 auricular, auriculo-ventricular, and aortic and pulmonary orifices; 
 the auricular orifices being the passages from the vense cavas and 
 
234 
 
 THE CIRCULATION. 
 
 pulmonary veins into the right and left auricles; the auriculo- 
 ventricular orifices leading from the auricles into the ventricles; 
 and the aortic and pulmonary orifices leading from the ventricles 
 into the aortic and pulmonary arteries respectively. 
 
 The auriculo-ventricular, aortic, and pulmonary orifices are fur- 
 nished with valves, which allow the blood to pass readily from the 
 auricles to the ventricles, and from the ventricles to the arteries, 
 but shut back with the contractions of the organ, so as to prevent 
 its return in an opposite direction. The course of the blood 
 through the heart is, therefore, as follows. From the vena cava it 
 passes into the right auricle; and from the right auricle into the 
 right ventricle. (Fig. 81.) On the contraction of the right ventricle, 
 the tricuspid valves shut back, preventing its return into the auricle 
 (Fig. 82); and it is thus driven through the pulmonary artery to the 
 
 Fig. 82. 
 
 Eight Auricle and Ventricle; Auriculo-ventricular Valves closed, Arterial Valves open. 
 
 lungs. Returning from the lungs, it enters the left auricle, thence 
 passes into the left ventricle, from which it is finally delivered into 
 the aorta, and distributed throughout the body. (Fig. 83.) This 
 movement of the blood, however, through the cardiac cavities, is 
 not a continuous and steady flow, but is accomplished by alternate 
 contractions and relaxations of the muscular parietes-of the heart; 
 so that with every impulse, successive portions of blood are received 
 by the auricles, delivered into the ventricles, and by them dis- 
 
THE HEART. 235 
 
 charged into the arteries. Each one of these successive actions is 
 called a beat, or pulsation of the heart. 
 
 Fig. 83. 
 
 Course op Blood through the Heart. — a, a. Vena cava, superior and inferior. 
 b. Right ventricle, c. Pulmonary artery, d. Pulmonary vein. e. Left ventricle. /. Aorta. 
 
 Each pulsation of the heart is accompanied by certain important 
 phenomena, which require to be studied in detail. These are the 
 sounds, the movements, and the impulse. 
 
 The sounds of the heart are two in number. They can readily be 
 heard by applying the ear ov,er the cardiac region, when they are 
 found to be quite different from each other in position, in tone, and 
 in duration. They are distinguished as the first and second sounds 
 of the heart. The first sound is heard with the greatest intensity 
 over the anterior surface of the heart, and more particularly over 
 the fifth rib and the fifth intercostal space. It is long, dull, and 
 smothered in tone, and occupies one-half the entire duration of a 
 single beat. It corresponds in time with the impulse of the heart 
 in the precordial region, and the stroke of the large arteries in the 
 immediate vicinity of the chest. The second sound follows imme- 
 diately upon the first. It is heard most distinctly at the situation 
 of the aortic and pulmonary valves, viz., over the sternum at the 
 level of the third costal cartilage. It is short, sharp, and distinct 
 in tone, and occupies only about one-quarter of the whole time of 
 
236 THE CIRCULATION. 
 
 a pulsation. It is followed by an equal interval of silence ; after 
 wliich the first sound again recurs. The whole time of a cardiac 
 pulsation may then be divided into four quarters, of which the first 
 two are occupied by the first sound, the third by the second sound, 
 and the fourth by an interval of silence, as follows : — 
 
 Time of pulsation. 
 
 ' 1st quarter \ 
 n , „ V First sound. 
 
 3d " Second sound. 
 
 4th " Interval of silence. 
 
 The cause of the second sound is universally acknowledged to be 
 the sudden closure and tension of the aortic and pulmonary valves. 
 This fact is established by the following proofs : 1st, this sound is 
 heard with perfect distinctness, as we have already mentioned, di- 
 rectly over the situation of the above-mentioned valves; 2d, the far- 
 ther we recede in any direction from this point, the fainter becomes 
 the sound ; and 3d, in experiments upon the living animal, often 
 repeated by different observers, it has been found that if a curved 
 needle be introduced into the base of the large vessels, so as to hook 
 back the semilunar valves, the second sound at once disappears, 
 and remains absent until the valve is again liberated. These valves 
 consist of fibrous sheets, covered with a layer of endocardial epithe- 
 lium. They have the form of semilunar festoons, the free edge of 
 which is directed away from the cavity of the ventricle, while the 
 attached edge is fastened to the inner surface of the base of the 
 artery. While the blood is passing from the ventricle to the artery, 
 these valves are thrown forward and relaxed ; but when the artery 
 reacts upon its contents they shut back, and their fibres, becoming 
 suddenly tense, yield a clear, characteristic, snapping sound. 
 
 The production of the first sound has been attributed by some 
 writers to a combination of various causes ; such as the rush of 
 blood through the cardiac orifices, the muscular contraction of the 
 parietes of the heart, the tension of the auriculo-ventricular valves, 
 the collision of the particles of blood with each other and with the 
 surface of the ventricle, &c. &c. We believe, however, with Andry' 
 and some others, that the first sound of the heart has a similar 
 origin with the second; and that it is dependent altogether on the 
 closure of the auriculo-ventricular valves. The reasons for this con- 
 clusion are the following : — 
 
 1st. The second sound is undoubtedly caused by the closure of 
 
 ' Diseases of the Heart, Kneeland's translation, Boston, 1846. 
 
THE HEART. 237 
 
 the semilunar valves, and in the action of the heart the shutting 
 back of the two sets of valves alternate with each other precisely 
 as do the first and second sounds; and there is every probability, 
 to say the least, that the sudden tension of the valvular fibres pro- 
 duces a similar effect in each instance. 
 
 2d. The first sound is heard most distinctly over the anterior 
 surface of the ventricles, where the tendinous cords supporting the 
 auriculo-ventricular valves are inserted, and where the sound pro- 
 duced by the tension of these valves would be most readily con- 
 ducted to the ear. 
 
 8d. There is no reason to believe that the current of blood 
 through the cardiac orifices could give rise to an appreciable sound, 
 so long as these orifices, and the cavities to which they lead, have 
 their normal dimensions. An unnatural souffle may indeed origi- 
 nate from this cause when the orifices of the heart are diminished 
 in size, as by. calcareous or fibrinous deposits; and it may also 
 occur in cases of aneurism. A souffle may even be produced at 
 will in any one of the large arteries by pressing firmly upon it 
 with the end of a stethoscope, so as to diminish its calibre. But in 
 all these instances, the abnormal sound occurs only in consequence 
 of a disturbance in the natural relation existing between the volume 
 of the blood and the size of the orifice through which it passes. 
 In the healthy heart, tbe different orifices of the organ are in exact 
 proportion to the quantity of the circulating blood ; and there is 
 no more reason for believing that its passage should give rise to a 
 sound in the cardiac cavities than in the larger arteries or veins. 
 
 4:th. The difference in character between the two sounds of the 
 heart depends, in all probability, on the different arrangement of 
 the two sets of valves. The second sound is short, sharp, and dis- 
 tinct, because the semilunar valves are short and narrow, superficial 
 in their situation, and supported by the highly elastic, dense and 
 fibrous bases of the aortic and pulmonary arteries. The first sound 
 is dull and prolonged, because the auriculo-ventricular valves are 
 broad and deep-seated, and are attached, by their long chordas 
 tendinese to the comparatively soft and yielding fleshy columns of 
 the heart. The difference between the first and second sounds can, 
 in fact, be easily imitated, by simply snapping between the fingers 
 two pieces of tape or ribbon, of the same texture but of different 
 lengths. (Fig. 84.) The short one will give out a distinct and sharp 
 sound ; the long one a comparatively dull and prolonged sound. 
 
 Together with the first sound of the heart there is also to be 
 
238 THE CIRCULATION. 
 
 heard a sW^i friction sound, produced by the collision of the point 
 of the heart against the parietes of the chest. This sound, which is 
 heard in the fifth intercostal space, is very faint, and is more or less 
 
 Fig. 84. 
 
 masked by the strong valvular sound which occurs at the same 
 time. It is different, however, in character from the latter, and 
 may usually be distinguished from it by careful examination. 
 
 The movements of the heart during the time of a pulsation are 
 of a peculiar character, and have been very often erroneously 
 described. In fact altogether the best description of the move- 
 ments of the heart which has yet appeared, is that given by Wil- 
 liam Harvey, in his celebrated work on the Motion of the Heart and 
 Blood, published in 1628. He examined the motion of the heart 
 by opening the chest of the living animal; and though the same or 
 similar experiments have been frequently performed since his time, 
 the descriptions given by subsequent observers have been for the 
 most part singularly inferior to his, both in clearness and fidelity. 
 The method which we have adopted for examining the motions of 
 the heart in the dog is as follows: The animal is first rendered 
 insensible by ether, or by the inoculation of woorara. The latter 
 mode is preferable, since a long-continued etherization seems to 
 exert a sensibly depressing effect on the heart's action, which is 
 not the case with woorara. The trachea is then exposed and 
 opened just below the larj'nx, and the nozzle of a bellows inserted 
 and secured by ligature. Finally, the chest is opened on the me- 
 dian line, its two sides widely separated, so as to expose the heart 
 and lungs, the pericardium slit up and, carefull}^ cut away from its 
 attachments, and the lungs inflated by insufflation through the 
 trachea. By keeping up a steady artificial respiration, the move- 
 
THE HEART. 239 
 
 ments of the heart may be made to continue, in favorable cases, for 
 more than an hour; and its actions may be studied by direct obser- 
 vation, like those of any external organ. 
 
 The examination, however, requires to be conducted with certain 
 precautions, which are indispensable to success. When the heart 
 is first exposed, its movements are so complicated, and recur with 
 such rapidity, that it is difficult to distinguish them perfectly from 
 each other, and to avoid a certain degree of confusion. Singular 
 as it may seem, it is even difficult at first to determine what period 
 in the heart's pulsation corresponds to contraction, and what to 
 relaxation of the organ. We have even seen several medical men, 
 watching together the pulsations of the same heart, unable to agree 
 upon this point. It is very evident, indeed, that several English 
 and continental observers have mistaken, in their examinations, the 
 contraction for the relaxation, and the relaxation for the contrac- 
 tion. The first point, therefore, which it is necessary to decide, in 
 examining the successive movements of a cardiac pulsation, is the 
 following, viz: Which is the contraction and which the relaxation of 
 the ventricles? The method which we have adopted is to pass a 
 small silver canula directly through the parietes of the left ven- 
 tricle into its cavity. The blood is then driven from the external 
 orifice of the canula in interrupted jets; each jet indicating the 
 time at which the ventricle contracts upon its contents. The 
 canula is then withdrawn, and the difierent muscular layers of the 
 ventricular walls, crossing each other obliquely, close the opening, 
 so that there is little or no subsequent hemorrhage. 
 
 When the successive actions of contraction and relaxation have 
 by this means been fairly recognized and distinguished from each 
 other, the cardiac pulsations are seen to be characterized by the 
 following phenomena. The changes in form and position of the 
 entire heart are mainly dependent on those of the ventricles, which 
 contract simultaneously with each other, and which constitute 
 much the largest portion of the entire mass of the organ. 
 
 1. At the time of its contraction the heart hardens. This pheno- 
 menon is exceedingly well marked, and is easily appreciated by 
 placing the finger upon the ventricles, or by grasping them between 
 the finger and thumb. The muscular fibres become swollen and 
 indurated, and if grasped by the hand communicate the sensation 
 of a somewhat sudden and powerful shock. It is this forcible indu- 
 ration of the heart, at the time of contraction, which has been mis- 
 taken by some writers for an active dilatation, and described as 
 
240 THE CIRCULATION. 
 
 such. It is, however, a phenomenon precisely similar to that which 
 takes place in the contraction of a voluntary muscle, which be- 
 comes swollen and indurated at the same moment and in the same 
 proportion that it diminishes in length, 
 
 2. At the time of contraction, the ventricles elongate and the 
 point of the heart protrudes. This phenomenon was very well 
 described by Dr. Harvey.^ "The heart," he says, "is erected, and 
 rises upward to a point, so that at this time it strikes against the 
 breast and the pulse is felt externally." The elongation of the 
 ventricles during contraction has, however, been frequently denied 
 by subsequent writers. The only modern observers, so far as we 
 are aware, who have recognized its existence, are Drs. C. W. Pen- 
 nock and Edward M. Moore, who performed a series of very careful 
 and interesting experiments on the action of the heart, in Philadel- 
 phia, in the year 1839.^ These experimenters operated upon calves, 
 sheep, and horses, by stunning the animal with a blow upon the 
 head, opening the chest, and keeping up artificial respiration. They 
 observed an elongation of the ventricle at the time of contraction, 
 and were even able to measure its extent by applying a shoemaker's 
 rule to the heart while in active motion. We are able to corroborate 
 entirely the statement of these observers by the result of our own 
 experiments on dogs, rabbits, frogs, &c. The ventricular contrac- 
 tion is an active movement, the relaxation entirely a passive one. 
 When contraction occurs and a stream of blood is thrown out of 
 the ventricle, its sides approximate each other and its point elon- 
 gates ; so that the transverse diameter of the heart is diminished, 
 and its longitudinal diameter increased. This can be readily felt 
 by grasping the base of the heart and the origin of the large vessels 
 gently between the first and middle fingers, and allowing the end 
 of the thumb of the same hand to rest lightly upon its apex. 
 With every contraction the thumb is sensibly lifted and separated 
 from the fingers, by a somewhat forcible elevatiou.of the point of 
 the heart. 
 
 The same thing can be seen, and even measured by the eye, 
 in the following manner : If the heart of the frog or even of any 
 small warm-blooded animal, as the rabbit, be rapidly removed from 
 the chest, it will continue to beat for some minutes afterward; and 
 when the rhythmical pulsations have finally ceased, contractions 
 
 ' Works of William Harvey, M. D. Sydenharii ed., Loiulon, 1847, p. 21. 
 ' Philadelphia Medical Kxiuiiiuer, No. 44. 
 
THE HEAET. 
 
 241 
 
 can still be readily excited by toucliing the heart with the point of 
 a steel needle. If the heart be now held by its base between the 
 thumb and finger, with its point directed upward, it will be seen 
 to have a pyramidal or conical form, representing very nearly in 
 its outline an equilateral triangle (Fig. 85) ; its base, while in a 
 condition of rest, bulging out laterally, while the apex is compara- 
 tively obtuse. 
 
 Fig. 85. 
 
 Fig. 86. 
 
 Heart of Froq 
 in a state of relaxa- 
 tion. 
 
 Heart of Frog iu contiaction. 
 
 When the heart, held in this position, is touched with the point 
 of a needle (Fig. 86), it starts up, becomes instantly narrower and 
 longer, its sides approximating and its point rising to an acute 
 ancle. This contraction is immediately followed by a relaxation ; 
 the point of the heart sinks down, and its sides again bulge out- 
 ward. 
 
 Let us now see in what manner this change in the figure of the 
 ventricles during contraction is produced. If the muscular fibres 
 of the heart were arranged in the form of 
 simple loops, running parallel with the 
 axis of the organ, the contraction of these 
 fibres would merely have the effect of di- 
 minishing the size of the heart in every 
 direction. This effect can be seen in the 
 accompanying hypothetical diagram (Fig. 
 87), where the white outline represents 
 such simple looped fibres in a state of re- 
 laxation, and the dotted internal line indi- 
 cates the form which they would take in 
 contraction. In point of fact, however, 
 none of the muscular fibres of the heart 
 
 run parallel to its longitudinal axis. They are disposed, on the 
 contrary, in a direction partly spiral and partly circular. The most 
 superficial fibres start from the base of the ventricles, and pass 
 16 
 
 Diagram of Simple Looped 
 Fibres, in relaxation and con- 
 traction. 
 
242 
 
 THE CIRCULATION. 
 
 toward the apex, curling round the heart in such a manner as to 
 pass over its anterior surface in an obliquely spiral direction, from 
 above downward, and from right to left. (Fig. 88.) They converge 
 
 toward the point of the heart, curl- 
 ing round the centre of its apex, and 
 then, changing their direction, be- 
 come deep-seated, run upward along 
 
 Fig. 89. 
 
 Fig. 88. 
 
 Bullock's Heart, anterior view, 
 showing the superficial muscular litres. 
 
 Left Ventricle op 
 BdLLOCK's Heart, show- 
 ing the deep fibres. 
 
 the septum and internal surface of the ventricles, and terminate 
 in the columnae carnese, and in the inner border of the auriculo- 
 ventricular ring. The deeper layers of fibres, on the contrary, are 
 wrapped round the ventricles in a nearly circular direction (Fig. 
 89); their points of origin and attachment being still the auriculo- 
 ventricular ring, and the points of the fleshy columns. The entire 
 arrangement of the muscular bundles may be readily seen in a 
 heart which has been boiled for six or eight hours, so as to soften 
 the connecting areolar tissue, and enable the fibrous layers to be 
 easily separated from each other. 
 
 By far the greater part of the mass of the fibres have therefore 
 a circular instead of a longitudinal direction. When they contract, 
 their action tends to draw the lateral walls of the ventricles together, 
 and thus to diminish the transverse diameter of the heart ; but as 
 each muscular fibre becomes thickened in direct proportion to its 
 contraction, their combined lateral swelling necessarily pushes out 
 the apex of the ventricle, and the heart elongates at the same time 
 that its sides are drawn together. This effect is illustrated in the 
 accompanying diagram (Fig. 90), where the white lines show the 
 ficrure of the heart durinor relaxation, with the course of its circular 
 
THE HEART. 
 
 243 
 
 Diagram of Circular Fibres 
 OF THE Heart, and their con- 
 traction. 
 
 fibres, while the dotted line shows the narrowed and elongated 
 
 figure necessarily produced by their contraction. This phenomenon, 
 
 therefore, of the protrusion of the apex 
 
 of the heart at the time of contraction, is 
 
 not only fully established by observation, 
 
 but is readily explained by the anatomical 
 
 structure of the organ. 
 
 3. Simultaneously with the hardening 
 and elongation of the heart, its apex moves 
 slightly from left to right, and rotates also 
 upon its own axis in the same direction. 
 Both these movements result from the 
 peculiar spiral arrangement of the cardiac 
 fibres. If we refer again to the preceding 
 diagrams, we shall see that, provided the 
 fibres were arranged in simple longitudi- 
 nal loops (Fig. 87), their contraction would 
 
 merely have the efl[ect of drawing the point of the heart directly 
 upward in a straight line toward its base. On the other hand, if 
 they were arranged altogether in a circular direction (Fig. 90), the 
 apex would be simply protruded forward, also in a direct line, 
 without deviating or twisting either to the 
 right or to the left. But iu point of fact, 
 the superficial fibres, as we have already 
 described, run spirally, and curling round 
 the point of the heart, turn inward toward 
 its base ; so that if the apex of the organ be 
 viewed externally, it will be seen that the 
 superficial fibres converge toward its cen- 
 tral point in curved lines, as in Fig. 91. It 
 is well known that every curved muscular 
 fibre, at the time of its shortening, necessa- 
 rily approximates more or less to a straight 
 
 line. Its curvature is diminished in exact proportion to the extent 
 of its contraction; and if arranged in a spiral form, its contraction 
 tends in the same degree to untwist the spiral. During the con- 
 traction of the heart, therefore, its apex rotates on its own axis in 
 the direction indicated by the arrows in Fig. 91, viz., from left to 
 right anteriorly, and from right to left posteriorly. This produces 
 a twisting movement of the apex in the above direction, which is 
 
 Fig. 91. 
 
 Converging Fibres or 
 THE Apex of the Heart. 
 
244 THE CIRCULATION. 
 
 very perceptible to the eye at every pulsation of the heart, when 
 exposed in the living animal. 
 
 4. The protrusion of the point of the heart at the time of con- 
 traction, together with its rotation upon its axis from left to right, 
 brings the apex of the organ in contact with the parietes of the 
 chest, and produces the shock or impulse of the heart, which is 
 readily perceptible externally, both to the eye and to the touch. 
 In the human subject, when in an erect position, the heart strikes 
 the chest in the fifth intercostal space, midway between the edge of 
 the sternum and a line drawn perpendicularly downward from the 
 left nipple. In a supine position of the body, the heart falls away 
 from the anterior parietes of the chest so much that the impulse may 
 disappear for the time altogether. This alternate recession and 
 advance of the point of the heart, in relaxation and contraction, 
 is provided for by the anatomical arrangement of the pericardium, 
 and the existence of the pericardial fluid. As the heart plays back- 
 ward and forward, the pericardial fluid constantly follows its 
 movements, receding as the heart advances, and advancing as the 
 heart recedes. It fulfils, in this respect, the same purpose as the 
 synovial fluid, and the folds of adipose tissue in the cavity of the 
 large articulations ; and allows the cardiac movements to take place 
 to their full extent without disturbing or injuring in any way the 
 adjacent organs. 
 
 5. The rhythm of the heart's pulsations is peculiar and somewhat 
 complicated. Each pulsation is made up of a double series of con- 
 tractions and relaxations. The two auricles contract together, and 
 afterward the two ventricles ; and in each case the contraction is 
 immediately followed by a relaxation. The auricular contraction 
 is short and feeble, and occupies the first part of the time of a 
 pulsation. The ventricular contraction is longer and more powerful, 
 and occupies the latter part of the same period. Following the 
 ventricular contraction there comes a short interval of repose, after 
 which the auricular contraction again recurs. The auricular and 
 ventricular contractions, however, do not alternate so distinctly 
 with each other (like the strokes of the two pistons of a fire engine) 
 as we should be led to believe from the accounts which have been 
 given by some observers. On the contrary, they are connected and 
 continuous. The contraction, which commences at the auricle, is 
 immediately propagated to the ventricle, and runs rapidly from the 
 base of the heart to its apex, very much in the manner of a peris- 
 taUic motion, except that it is more sudden and vigorous. 
 
THE HEAKT. 245 
 
 William Harvey, again, gives a better account of this part of the 
 heart's action than has been published by any subsequent writer. 
 The following exceedingly graphic and appropriate description, 
 taken from his book, shows that he derived his knowledge, not 
 from any secondary or hypothetical sources, but from direct and 
 careful study of the phenomena in the living animal. 
 
 " First of all," he says,' " the auricle contracts, and in the course 
 of its contraction throws the blood (which it contains in ample 
 quantity as the head of the veins, the storehouse and cistern of the 
 blood) into the ventricle, which being filled, the heart raises itself 
 straightway, makes all its fibres tense, contracts the ventricles, and 
 performs a beat, by which beat it immediately sends the blood 
 supplied to it by the auricle, into the arteries; the right ventricle 
 sending its charge into the lungs by the vessel which is called vena 
 arteriosa, but which, in structure and function, and all things else, 
 is an artery ; the left ventricle sending its charge into the aorta, 
 and through this by the arteries to the body at large. 
 
 " These two motions, one of the ventricles, another of the auricles, 
 take place consecutively, but in such a manner that there is a kind 
 of harmony or rhythm preserved between them, the two concurring 
 in such wise that but one motion is apparent, especially in the 
 warmer blooded animals, in which the movements in question are 
 rapid. Nor is this for any other reason than it is in a piece of 
 machinery, in which, though one wheel gives motion to another, 
 yet all the wheels seem to move simultaneously ; or in that 
 mechanical contrivance which is adapted to fire-arms, where the 
 trigger being touched, down comes the flint, strikes against the 
 steel, elicits a spark, which falling among the powder, it is ignited, 
 upon which the flame extends, enters the barrel, causes the explo- 
 sion, propels the ball, and the mark is attained ; all of which 
 incidents, by reason of the celerity with which they happen, seem 
 to take place in the twinkling of an eye." 
 
 The above description indicates precisely the manner in which 
 the contraction of the ventricle follows successively and yet con- 
 tinuously upon that of the auricle. The entire action of the auricles 
 and ventricles during a pulsation is accordingly as follows : The 
 contraction begins, as we have already stated, at the auricle. 
 Thence it runs immediately forward to the apex of the heart. The 
 entire ventricle contracts vigorously, its walls harden, its apex 
 
 • Op. cit.,p. 31. 
 
246 THE CIRCULATION. 
 
 protrudes, strikes against the walls of the chest, and twists from 
 left to right, the auriculo- ventricular valves shut back, the first 
 sound is produced, and the blood is driven into the aorta and 
 pulmonary artery. These phenomena occupy about one-half the 
 time of an entire pulsation. Then the ventricle is immediately 
 relaxed, and a short period of repose ensues. During this period 
 the blood flows in a steady stream from the large veins into the 
 auricle, and through the auriculo-ventricular orifice into the ven- 
 tricle ; filling the ventricle, by a kind of passive dilatation, about 
 two-thirds or three-quarters full. Then the auricle contracts with 
 a quick sharp motion, forces the last drop of blood into the ventricle, 
 distending it to its full capacity, and then the ventricular contraction 
 follows, as above described, driving the blood into the large arteries. 
 These movements of contraction and relaxation continue to alternate 
 with each other, and form, by their recurrence, the successive 
 cardiac pulsations. 
 
 THE ARTERIES AND THE ARTERLAL CIRCULATION. 
 
 The arteries are a series of branching tubes which commence 
 with the aorta and ramify throughout the body, distributing the 
 blood to all the vascular organs. They are composed of three 
 coats, viz : an internal homogeneous tunic, continuous with the 
 endocardium; a middle coat, composed of elastic and muscular 
 fibres ; and an external or " cellular" coat, composed of condensed 
 layers of areolar tissue. The essential anatomical difference be- 
 tween tbe larger and the smaller arteries consists in the structure 
 of their middle coat. In the smaller arteries this coat is composed 
 exclusively of smooth muscular fibres, arranged in a circular 
 manner around the vessel, like the circular fibres of the muscular 
 coat of the intestine. In arteries of medium size the middle coat 
 contains both muscular and elastic fibres; while in those of the 
 largest calibre it consists of elastic tissue alone. The large arteries, 
 accordingly, possess a remarkable degree of elasticity and little or 
 no contractility ; while the smaller are contractile, and but little or 
 not at all elastic. 
 
 It is found, by measuring the diameters of the successive arte- 
 rial ramifications, that the combined area of all the branches given 
 off' from a trunk is somewhat greater than that of the original 
 
THE ARTERIES AND THE ARTERIAL CIRCULATION. 247 
 
 vessel; and therefore that the combined area of all the small 
 arteries must be considerably larger than that of the aorta, from 
 which the arterial system originates. As the blood, consequently, 
 in its passage from the heart outward, flows successively through 
 larger and larger spaces, the rapidity of its circulation must neces- 
 sarily be diminished, in the same proportion as it recedes from the 
 heart. It is driven rapidly through the larger trunks, more slowly 
 through those of medium size, and more slowly still as it approaches 
 the termination of the arterial system and the commencement of 
 the capillaries. 
 
 The movement of the blood through the arteries is primarily caused 
 by the contractions of the heart ; but is, at the same time, regulated 
 and modified by the elasticity of the vessels. The mode in which 
 the arterial circulation takes place is as follows. At the time of the 
 heart's contraction, the muscular walls of the ventricle act power- 
 fully upon its fluid contents. The auriculo- ventricular valves at 
 the same time shutting back and preventing the blood from regur- 
 gitating into the auricle, it is forced out through the aortic orifice. 
 A charge of blood is therefore driven into that part of the aorta 
 nearest the heart, by which the artery is distended in exact propor- 
 tion to the force of the heart's action and the quantity of blood 
 which it expels. When the ventricle relaxes, the distending force 
 is removed ; and the elastic arterial walls, reacting upon their con- 
 tents, would force the blood back again into the heart, were it not 
 for the semilunar valves which shut together and close the aortic 
 orifice. The column of blood is accordingly forced onward, into 
 the next division of the arterial system, which is distended in its 
 tufn and reacts again upon the blood, driving the blood necessarily 
 farther and farther from the heart, until it arrives at the confines of 
 the capillary system. In this manner a succession of waves or im- 
 pulses is propagated from the heart outward (Fig. 92), consisting 
 of the alternate distension and reaction of different portions of the 
 artery, and which is readily perceptible whenever the vessel occu- 
 pies a superficial position. This phenomenon is known by the 
 name of the arterial 'pulse. 
 
 When the blood is thus driven by the cardiac pulsations into the 
 artery, the vessel is not only "distended laterally, but is elongated 
 as well as widened, and enlarged in every direction. Particularly 
 when the vessel takes a curved or serpentine course, its elongation 
 and the increase of its curvatures may be observed at every pulsa- 
 
248 
 
 THE CIECULATIOISr. 
 
 tion. This may be seen, for example, in the temporal arteries, or 
 even in the radial arteries, in emaciated persons. It is also very 
 well seen in the mesenteric arteries, when the abdomen is opened 
 
 Fig. 92. 
 
 Diagram of Arterial Circulation. 
 
 in the living animal. At every contraction of the heart the curves 
 of the artery on each side become more strongly pronounced. (Fig. 
 93.) The vessel even rises up partially out of its 
 bed, particularly where it runs over a bony sur- 
 face, as in the case of the radial artery. In old 
 persons the curves of the vessels become perma- 
 nently enlarged from frequent distension ; and all 
 the arteries tend to assume, with the advance of 
 age, a more serpentine and even spiral course. 
 
 Owing to the alternating contractions and re- 
 laxations of the heart, the blood passes through 
 the arteries, not in a steady stream, but, as already 
 described, in a series of welling impulses; and 
 the hemorrhage from a wounded artery is readily 
 distinguished from venous or capillary hemor- 
 rhage by the fact that the blood flows in suc- 
 cessive jets, as well as more rapidly and abund- 
 antly. If a puncture be made in the walls of the 
 ventricle, and a slender canula introduced, the flow of the blood 
 through it is seen to be entirely intermittent. A strong jet takes 
 place at each ventricular contraction, and at each relaxation the 
 flow is completely interrupted. If the puncture be made, however, 
 in any of the large arteries near the heart, the flow of blood through 
 the orifice is no longer intermittent, but is continuous ; only it is 
 very much stronger at the time of ventricular contraction, and 
 diminishes, though it does not entirely cease, at the time of relaxa- 
 tion. This is on account of the elasticity of the arterial coats. For 
 if the blood were driven through a series of perfectly rigid and 
 unyielding tubes, its flow would be everywhere intermittent ; and it 
 would be delivered from an orifice situated at any point, in perfectly 
 
 Elungation and curva- 
 ture of an Artert in 
 
 PULSATION. 
 
THE ARTERIES AND THE ARTERIAL CIRCULATION. 249 
 
 interrupted jets. But the arteries are yielding and elastic. When 
 the contraction of the heart drives the blood into the aorta, a part 
 of its force is expended for the time in distending the walls of the 
 vessel; and this force is returned to the blood, when the heart 
 relaxes, by the elastic reaction of the arterial coats. The interrupted 
 or pulsating character of the arterial current, therefore, which is 
 strongly pronounced in the immediate vicinity of the heart, becomes 
 gradually lost and equalized, during its passage through the vessels, 
 until in the smallest arteries it is nearly imperceptible. 
 
 The same effect of an elastic medium in equalizing the force of 
 an interrupted current may be shown by fitting to the end of a 
 common syringe a long glass or metallic tube. Whatever be the 
 length of the inelastic tubing, the water which is thrown into one 
 extremity of it by the syringe will be delivered from the other end 
 in distinct jets, corresponding with the strokes of the piston ; but if 
 the metallic tube be replaced by one of India rubber, of sufficient 
 length, the elasticity of this substance merges the force of the sepa- 
 rate impulses into each other, and the water is driven out from the 
 farther extremity in a continuous stream. 
 
 The elasticity of the arteries, however, never entirely equalizes 
 the force of the separate cardiac pulsations, since a pulsating cha- 
 racter can be seen in the flow of the blood through even the smallest 
 arteries, under the microscope; but this pulsating character dimin- 
 ishes very considerably from the heart outward, and the current 
 becomes much more continuous in the smaller vessels than in the 
 larger. 
 
 The primary cause, therefore, of the motion of the blood in the 
 arteries is the contraction of the ventricles, which, by driving out 
 the blood in interrupted impulses, distends at every stroke the 
 whole arterial system. But the arterial pulse is not exactly syn- 
 chronous everywhere with the beat of the heart; since a certain 
 amount of time is required to propagate the blood-wave from the 
 centre of the circulation outward. The pulse of the radial artery 
 at the wrist is perceptibly later than that of the heart ; and the 
 pulse of the posterior tibial at the ankle, again, perceptibly later 
 than that at the wrist. The arterial circulation, accordingly, is not 
 an entirely simple phenomenon ; but is made up of the combined 
 effects of two different physical forces. In the first place, there is 
 the elasticity of the entire arterial system, by which the blood is 
 subjected to a constant and uniform pressure, quite independent of 
 the action of the heart. Secondly, there is the alternating contrac- 
 
250 THE CIRCULATION". 
 
 tion and relaxation of the heart, by which the blood is driven in 
 rapid and successive impulses from the centre of the circulation, to 
 be thence distributed throughout the body. 
 
 The rapidily with which the blood circulates through the arterial 
 system is very great. Its velocity is greatest in the immediate 
 neighborhood of the heart, and diminishes somewhat as the blood 
 recedes farther and farther from the centre of the circulation. This 
 diminution in the rapidity of the arterial current is due to the suc- 
 cessive division of the aorta and its primary branches into smaller 
 and smaller ramifications, by which the total calibre of the arterial 
 system, as we have already mentioned, is somewhat increased. The 
 blood, therefore, flowing through a larger space as it passes outward, 
 necessarily goes more slowly. At the same time the increased 
 extent of the arterial parietes with which the blood comes in con- 
 tact, as well as the mechanical obstacle arising from the division of 
 the vessels and the separation of the streams, undoubtedly contri- 
 bute more or less to retard the currents. The mechanical obstacle, 
 however, arising from the friction of the blood against the walls of 
 the vessels, which would be very serious in the case of water or any 
 similar fluid flowing through glass or metallic tubes, has compara- 
 tively little effect on the rapidity of the arterial circulation. This 
 can readily be seen by microscopic examination of any transparent 
 and vascular tissue. The internal surface of the arteries is so smooth 
 and yielding, and the consistency of the circulating fluid so accu- 
 rately adapted to that of the vessels which contain it, that the 
 retarding effects of friction are reduced to a minimum, and the 
 blood in flowing through the vessels meets with the least possible 
 resistance. 
 
 It is owing to this fact that the arterial circulation, though some- 
 what slower toward the periphery than near the heart, yet retains 
 a very remarkable velocity throughout ; and even in arteries of the 
 minutest size it is so rapid that the shape of the blood-globules can- 
 not be distinguished in it on microscopic examination, but only a 
 mingled current shooting forward with increased velocity at every 
 cardiac pulsation. Yolkmann, in Germany, has determined, by a 
 very ingenious contrivance, the velocity of the current of blood in 
 some of the large sized arteries in dogs, horses, and calves. The 
 instrument which he employed (Fig. 94) consisted of a metallic 
 cylinder (a), with a perforation running from end to end, and cor- 
 responding in size with the artery to be examined. The artery was 
 then divided transversely, and its cardiac extremity fastened to the 
 
THE ARTERIES AND THE ARTERIAL CIRCULATION. 251 
 
 upper end (h) of the instrument, while its peripheral extremity was 
 fastened in the same manner to the lower end (c). The blood 
 accordingly still kept on its usual course; only passing for a short 
 distance through the artificial tube (a), between the divided extremi- 
 
 Fig. 94. Fig- 95. 
 
 VoLKMANN's APPARATUS for measuring the rapidity of the arterial circulation. 
 
 ties of the artery. The instrument, however, was provided, as shown 
 in the accompanying figures, with two transverse cylindrical plugs, 
 also perforated f and arranged in such a manner, that when, at u 
 given signal, the two plugs were suddenly turned in opposite 
 directions, the stream of blood would be turned out of its course 
 (Fig. 95), and made to traverse a long bent tube of glass {d, d, d), 
 before again finding its way back to the lower portion of the artery. 
 In this way the distance passed over by the blood in a given tii:ie 
 could be readily measured upon a scale attached to the side of the 
 glass tube. Volkmann found, as the average result of his obser- 
 vations, that the blood moves in the carotid arteries of warm-blooded 
 quadrupeds with a velocity of 12 inches per second. 
 
252 THE CIRCULATION. 
 
 VENOUS CIRCULATION. 
 
 The veins, which collect the blood from the tissues and return it 
 to the heart, are composed, like the arteries, of three coats ; an 
 inner, middle, and exterior. In structure, they differ from the arte- 
 ries in containing a much smaller quantity of muscular and elastic 
 fibres, and a larger proportion of simple condensed areolar tissue. 
 They are consequently more flaccid and compressible than the 
 arteries, and less elastic and contractile. They are furthermore 
 distinguished, throughout the limbs, neck, and external portions of 
 the head and trunk, by being provided with valves, consisting of 
 fibrous sheets arranged in the form of festoons, and so placed in the 
 cavity of the vein as to allow the blood to pass readily from the 
 periphery toward the heart, but to prevent altogether its reflex in 
 an opposite direction. 
 
 The flow of blood through the veins is less powerful and regular 
 than that through the arteries. It depends on the combined action 
 of three different forces. 
 
 1. The force of aspiration of the thorax. — When the chest expands, 
 by the lifting of the ribs and the descent of the diaphragm, it has 
 the effect of drawing into the thoracic cavity all the fluids which 
 can gain access to it. The expanded cavity is principally filled 
 by the air, which passes in through the trachea and fills the 
 bronchial tubes and pulmonary vesicles. But the blood in the 
 large veins is also drawn into the chest at the same time and by 
 the same force. It can readily be seen, when the jugular and sub- 
 clavian veins are exposed in the living animal, that these vessels 
 collapse with every inspiration, and fill out again at the moment of 
 expiration. During inspiration, the blood is drawn forward into 
 that part of the vein which occupies the cavity of the chest ; and 
 during expiration, the flow being momentarily checked by the 
 compression of the thorax, the vein fills up from behind, and again 
 becomes distended. This force does not act efficiently at any great 
 distance from the chest, owing to the flaccidity of the venous parietes, 
 which collapse at a short distance from the entrance to the thoracic 
 cavity, as the vein becomes emptied by inspiration. It is active, 
 however, in the neighborhood of the chest, and the respiratory 
 movements exert, therefore, a certain degree of influence on the 
 venous circulation. 
 
VENOUS CIECULATION 
 
 253 
 
 2. Tlie contraction of the voluntary muscles. — The veins which 
 convey the blood through the limbs, and the parietes of the head 
 and trunk, lie among voluntary muscles, which are more or less 
 constantly in a state of alternate contraction and relaxation. At 
 every contraction these muscles become swollen laterally, and, of 
 course, compress the veins which are situated between them. The 
 blood, driven out from the vein by this pressure, cannot regurgitate 
 toward the capillaries, owing to the valves, already described, which 
 shut back and prevent its reflux. It is accordingly forced onward 
 toward the heart; and when the muscle relaxes and the vein is 
 liberated from pressure, it again fills up from behind, and the cir- 
 culation goes on as before. This force is a very efficient one in 
 producing the venous circulation ; since the voluntary muscles are 
 more or less active in every position of the body, and the veins 
 constantly liable to be compressed by them. It is on this account 
 that the veins, in the external parts of the body, communicate so 
 freely with each other by transverse branches ; in order that the 
 current of blood, which is momentarily excluded from one vein by 
 the pressure of the muscles, may readily find a passage through 
 others, which communicate by cross branches with the first. (Figs. 
 96 and 97.) 
 
 Fig. 96. 
 
 Fig. 97. 
 
 Vein with valves open. 
 
 Vein with valves closed; stream of 
 blood passing off by a lateral channel. 
 
 3. The force of the capillary circulation. — This last cause of the 
 motion of the blood through the veins is the most important of all, 
 as it is the only one which is constantly and universally active. In 
 
254 THE CIRCULATION. 
 
 fish, for example, respiration is performed altogether by gills; and 
 in reptiles the air is forced down into the lungs by a kind of deglu- 
 tition, instead of being drawn in by the expansion of the chest. In 
 neither of these classes, therefore, can the movements of respiration 
 assist mechanically in the circulation of the blood. In the splanch- 
 nic cavities, again, of all the vertebrate animals, the veins coming 
 from the internal organs, as, for example, the cerebral, pulmonary, 
 portal, hepatic, and renal veins, are unprovided with valves ; and 
 the passage of the blood through them cannot therefore be effected 
 by any lateral pressure. The circulation, however, constantly going 
 on in the capillaries, everywhere tends to crowd the radicles of the 
 veins with blood ; and this vis a tergo, or pressure from behind, fills 
 the whole venous system by a constant and steady accumulation. 
 So long, therefore, as the veins are relieved of blood at their cardiac 
 extremity by the regular pulsations of the heart, there is no back- 
 ward pressure to oppose the impulse derived from the capillary cir- 
 culation ; and the movement of the blood through the veins continues 
 in a steady and uniform course. 
 
 With regard to the rapidity of the venous circulation, no direct 
 results have been obtained by experiment. Owing to the flaccidity 
 of the venous parietes, and the readiness with which the flow of 
 blood through them is disturbed, it is not possible to determine this 
 point for the veins, in the same manner as it has been determined 
 for the arteries. The only calculation which has been made in this 
 respect is based upon a comparison of the total capacity of the 
 arterial and venous systems. As the same blood which passes out- 
 ward through the arteries, passes inward again through the veins, 
 the rapidity of its flow in each must be in inverse proportion to the 
 capacity of the two sets of vessels. That is to say, a quantity of 
 blood which would pass in a given time, with a velocity of x, 
 through an opening equal to one square inch, would pass during 
 the same time through an opening equal to two square inches, with 
 a velocity of J; and would require, on the other hand, a velocity 
 of 2 «, to pass in the same time through an opening equal to one- 
 half a square inch. Now the capacity of the entire venous system, 
 when distended by injection, is about twice as great as that of the 
 entire arterial system. During life, however, the venous system is 
 at no time so completely filled with blood as is the case with the 
 arteries ; and making allowance for this difference, we find that the 
 entire quantity of venous blood is to the entire quantity of arte- 
 
THE CAPILLARY CIKCULATION. 
 
 255 
 
 rial blood nearly as three to two. The velocity of the venous 
 blood, as compared with the arterial, is therefore as two to three ; 
 or about 8 inches per second. It will be understood, however, that 
 this calculation is altogether approximative, and not exact ; since 
 the venous current varies, according to many different circumstances, 
 in different parts of the body ; being slower near the capillaries, 
 and more rapid near the heart. It expresses, however, with sufl&- 
 cient accuracy, the relative velocity of the arterial and venous cur- 
 rents, at corresponding parts of their course. 
 
 THE CAPILLARY CIRCULATION. 
 
 The capillary bloodvessels are minute inosculating tubes, which 
 permeate the vascular organs in every direction, and bring the 
 blood into intimate contact with the substance of the tissues. They 
 are continuous with the terminal ramifications of the arteries on 
 the one hand, and with the com- 
 mencing rootlets of the veins on Fig- 98. 
 the other. They vary somewhat 
 in size in different organs, and in 
 different species of animals ; their 
 average diameter in the human 
 subject being a little over 3 (jVw of 
 an inch. They are composed of 
 a single, transparent, homogene- 
 ous, somewhat elastic, tubular 
 membrane, which is provided at 
 various intervals with flattened, 
 oval nuclei. As the smaller arte- 
 ries approach the capillaries, they 
 diminish constantly in size by 
 successive subdivision, and lose 
 first their external or fibrous 
 tunic. They are then composed 
 
 only of the internal or homogeneous coat, and the midde or muscu- 
 lar. (Fig. 98, a.) The middle coat then diminishes in thickness, 
 until it is reduced to a single layer of circular, fusiform, unstriped, 
 muscular fibres, which in their turn disappear altogether as the 
 artery merges at last in the capillaries ; leaving only, as we have 
 
 SiMALL AuTERT, wUh its muscular tiiaic 
 (a), breaking up into capillaries. From the 2Jia 
 ■mater. 
 
256 
 
 THE CIECULATIOX. 
 
 already mentioned, a simple, homogeneous, nucleated, tubular mem- 
 brane, which is continuous with the internal arterial tunic. 
 
 The capillaries are further distinguished from both arteries and 
 veins by their frequent inosculation. The arteries constantly 
 divide and subdivide, as they pass from within outward; while 
 the veins as constantly unite with each other to form larger and 
 less numerous branches and trunks, as they pass from the circum- 
 ference toward the centre. But the capillaries simply inosculate 
 with each other in every direction, in such a manner as to form an 
 interlacing network or plexus, the capillary plexus (Fig. 99), which 
 is exceedingly rich and abundant in some organs, less so in others. 
 The spaces included between the meshes of the capillary network 
 vary also, in shape as well as in size, in different parts of the body. 
 
 In the muscular tissue they 
 '^' form long parallelograms ; in 
 
 the areolar tissue, irregular 
 shapeless figures, correspond- 
 ing with the direction of the 
 fibrous bundles of which the 
 tissue is composed. In the 
 mucous membrane of the 
 large intestine, the capillaries 
 include hexagonal or nearly 
 circular spaces, inclosing the 
 orifices of the follicles. In 
 the papillae of the tongue and 
 of the skin, and in the tufts 
 of the placenta, they are 
 arranged in long spiral loops, 
 and in the adipose tissue in wide meshes, among which the fat 
 vesicles are entangled. 
 
 The motion of the hlood in the cajnllaries may be studied by 
 examining under the microscope any transparent tissue, of a 
 sufficient degree of vascularity. One of the most convenient parts 
 for this purpose is the web of the frog's foot. "When properly 
 prepared and kept moistened by the occasional addition of water 
 to the integument, the circulation will go on in its vessels for an 
 indefinite length of time. The blood can be seen entering the 
 field by the smaller arteries, shooting along through them with 
 great rapidity and in successive impulses^ and flowing off again by 
 the veins at a somewhat slower rate. In the capillaries themselves 
 
 Capillary Network from tveb of frog's foot. 
 
THE CAPILLARY CIRCULATION. 
 
 257 
 
 Capillary Circulation in web of frog's foot. 
 
 the circulation is considerably less rapid than in either the arteries 
 or the veins. It is also perfectly steady and uninterrupted in its 
 flow. The blood passes along in a uniform and continuous current, 
 without any apparent contraction or dilatation of the vessels, very 
 much as if it were flowing 
 
 through glass tubes. An- ^^s- ^^^• 
 
 other very remarkable pe- 
 culiarity of the capillary 
 circulation is that it has no 
 definite direction. The nu- 
 merous streams of which it 
 is composed (Fig. 100) do 
 not tend to the right or to 
 the left, nor toward any one 
 particular point. On the 
 contrary, they pass above 
 and below each other, at 
 right angles to each other's 
 course, or even in opposite 
 directions; so that the blood, 
 while in the capillaries, merely circulates promiscuously among 
 the tissues, in such a manner as to come intimately in contact with 
 every part of their substance. 
 
 The motion of the white and red globules in the circulating blood 
 is also peculiar, and shows very distinctly the difference in their 
 consistency and other physical properties. In the larger vessels 
 the red globules are carried along in a dense column, in the central 
 part of the stream ; while near the edges of the vessel there is a 
 transparent space occupied only by the clear plasma of the blood, 
 in which no red globules are to be seen. In the smaller vessels, 
 the globules pass along in a narrower column, two by two, or 
 following each other in single file. The flexibility and semi-fluid 
 consistency of these globules are here very apparent, from the 
 readiness with which they become folded up, bent or twisted in 
 turning corners, and the ease with which they glide through minute 
 branches of communication, smaller in diameter than themselves. 
 The white globules, on the other hand, flow more slowly and with 
 greater difficulty through the vessels. They drag along the exter- 
 nal portions of the current, and are sometimes momentarily arrested; 
 apparently adhering for a few seconds to the internal surface of the 
 vessel. Whenever the current is obstructed or retarded in any 
 17 
 
258 THE CIRCULATION. 
 
 manner, the white globules accumulate in the affected portion, and 
 become more numerous there in proportion to the red. 
 
 It is during the capillary circulation that the blood serves for 
 the nutrition of the vascular organs. Its fluid portions slowly 
 transude through the walls of the vessels, and are absorbed by the 
 tissues in such proportion as is requisite for their nourishment. 
 The saline substances enter at once into the composition of the 
 surrounding parts, generally without undergoing any change. The 
 phosphate of lime, for example, is taken up in large quantity by 
 the bones and cartilages, and in smaller quantity by the softer parts; 
 while the chlorides of sodium and potassium, the carbonates, sul- 
 phates, &c., are appropriated in special proportions by the different 
 tissues, according to the quantity necessary for their organization. 
 The albuminous ingredients of the blood, on the other hand, are 
 not only absorbed in a similar manner by the animal tissues, but at 
 the same time are transformed by catalysis, and converted into new 
 materials, characteristic of tbe different tissues. In this way are 
 produced the musculine of the muscles, the osteine of the bones, the 
 cartilagine of the cartilages, &c. &c. It is probable that this trans- 
 formation does not take place in the interior of the vessels them- 
 selves ; but that the organic ingredients of the blood are absorbed 
 by the tissues, and at the same moment converted into new mate- 
 rials, by contact with their substance. The blood in this way fur- 
 nishes, directly or indirectly, all the materials necessary for the 
 nutrition of the body. 
 
 The physical forces which produce the movement of the blood 
 through the capillary vessels are different from those which operate 
 in producing the venous and arterial circulations. The force of the 
 heart's action, whicb drives the blood througb the arteries, merely 
 secures a constant supply of blood to the commencement of the 
 capillaries, but is not of itself the cause of the continued current 
 through the latter vessels. This is shown by the fact that a capil- 
 lary circulation exists in vegetables, where there is no central con- 
 tractile organ, and where the circulation of the sap must necessarily 
 depend on other forces. In fish, again, the heart is separated from 
 the general circulation by the capillary system of the gills, which 
 intervenes between them, and by which the impulsive force of the 
 cardiac contractions must be, to say the least, very much diminished. 
 In the quadrupeds, also, and in the human subject, the bepatic 
 capillary circulation goes on with the same regularity as elsewhere, 
 notwithstanding that it is supplied by the portal vein with blood 
 
THE CAPILLARY CIRCULATION. 259 
 
 which has already passed through the capillaries of the digestive 
 apparatus before reaching those of the liver. Furthermore, it is evi- 
 dent, from the commonest observation, that the capillary circulation, 
 in various parts of the body, is liable to be increased or diminished 
 in activity from causes of a purely local character, and entirely inde- 
 pendent of the action of the heart. The countenance may become 
 flushed or pale, and temporary congestions may take place in any 
 of the internal organs, as, for example, in the stomach and intestine 
 during the digestive process ; so that a much larger quantity of 
 blood may circulate through them in a given time, though the 
 force of the heart's action remains constant. 
 
 The study of the microscopic appearances of inflammation in 
 transparent tissues, so well observed by Lebert^ and others, leads to 
 a similar result. At the time when the inflammatory process begins 
 to be established, the circulation is seen to be retarded. The blood 
 moves more slowly through the capillaries, and its current becomes 
 more and more sluggish as the morbid action proceeds. The blood- 
 globules become impacted in the vessels, and finally, at those points 
 where the inflammation is most active, the circulation stops alto- 
 gether, and a local stasis of the blood is produced. This, however, 
 is not owing to any simple mechanical obstacle to its passage, since 
 the vessels, during the entire period of the inflammatory congestion, 
 are actually dilated by the blood which accumulates in them ; nor, 
 on the other hand, is it owing to a diminution in the force of the 
 heart's action, since the cardiac pulsations are still as powerful as 
 ever, and in the healthy tissues, in the immediate neighborhood of 
 the inflamed parts, the circulation may be seen going on at the 
 same time in its ordinary manner. 
 
 All these facts show beyond a doubt that the force which regu- 
 lates and controls the capillary circulation is a local one, and resident 
 evidently in the capillaries and tissues of the part itself. This force 
 not only carries the blood through the capillaries, but delivers it 
 also into the veins ; and by supplying the requisite vis a iergo^ con- 
 stitutes, as we have already mentioned, one of the most eflBeient 
 causes of the venous circulation. It is not only independent to a 
 certain extent, during life, of the heart's action, but will even con- 
 tinue for a time after the heart has stopped; so that at the moment 
 of death, when the cardiac pulsations cease, the capillaries empty 
 themselves of blood, which accumulates in the large trunks and 
 
 ' Pliysiologie Pathol ogique, Paris, 1845, voL i. p. 2. 
 
260 THE CIRCULATION. 
 
 branches of the veins. Precisely what is the nature of this force, 
 thus active in producing the capillary circulation, it is not easy to 
 determine. In all probability it results, in great measure, from the 
 actions of endosmosis and exosmosis, which are constantly going on 
 between the blood contained in the capillaries, and the tissues situated 
 outside of them ; and which, varying in intensity in different organs, 
 and even in the same organ at different times, produce those local 
 variations in the activity of the capillary circulation which con- 
 stantly present themselves to the observation of the physiologist. 
 
 The rapidity of the circulation in the capillary vessels is much 
 less than in the arteries or the veins. It may be measured, with 
 a tolerable approach to accuracy, during the microscopic examina- 
 tion of transparent and vascular tissues, as, for example, the web of 
 the frog's foot, or the mesentery of the rat. The results obtained 
 in this way by different observers (Valentine, Weber, Volkmann, 
 &c.) show that the rate of movement of the blood through the 
 capillaries is rather less than one-thirtieth of an inch per second ; 
 or not quite two inches per minute. Since the rapidity of the 
 current, as we have mentioned above, must be in inverse ratio to 
 the entire calibre of the vessels through which it moves, it follows 
 that the united calibre of all the capillaries of the body must be 
 from 350 to 400 times greater than that of the arteries. It must 
 not be supposed from this, however, that the whole quantity of blood 
 contained in the capillaries at any one time is so much greater than 
 that in the arteries ; since, although the united calibre of the capil- 
 laries is very large, their length is very small. The effect of the 
 anatomical structure of the capillary system is, therefore, merely to 
 disseminate a comparatively small quantity of blood over a very 
 large space, so that the chemico-physiological reactions, necessary 
 to nutrition, may take place with promptitude and energy. For 
 the same reason, although the rate of movement of the blood in 
 these vessels is very slow, yet as the distance to be passed over 
 between the arteries and veins is very small, the blood really re- 
 quires but a short time to traverse the capillary system, and to 
 commence its returning passage by the veins. 
 
 GENERAL CONSIDERATIONS. 
 
 The rapidity with which the blood passes through the entire round 
 of the circulation is a point of great interest, and one which has 
 
KAPIDITY OF THE CIRCULATION. 261 
 
 received a considerable share of attention. The results of such 
 experiments, as have been tried, show that this rapidity is much 
 greater than would have been anticipated. Hering, Poisseuille, and 
 Matteucci,* have all experimented on this subject in the following 
 manner. A solution of ferrocyanide of potassium was injected 
 into the right jugular vein of a horse, at the same time that a liga- 
 ture was placed upon the corresponding vein on the left side, and 
 an opening made in it above the ligature. The blood flowing from 
 the left jugular vein was then received in separate vessels, which 
 were changed every five seconds, and the contents afterward exa- 
 mined. It was thus found that the blood drawn from the first to 
 the twentieth second contained no traces of the ferrocyanide ; but 
 that which escaped from the vein at the end of from twenty to 
 twenty-five seconds, showed unmistakable evidence of the presence 
 of the foreign salt. The ferrocyanide of potassium must therefore, 
 during this time, have passed from the point of injection to the 
 right side of the heart, thence to the lungs and through the pulmo- 
 nary circulation, returned to the heart, passed out again through 
 the arteries to the capillary system of the head and neck, and 
 thence have commenced its returning passage to the right side of 
 the heart, through the jugular vein. 
 
 If this experiment were altogether decisive, it would demonstrate 
 that the blood performs the entire round of the circulation in from 
 20 to 25 seconds. But it is not so conclusive in this respect as might 
 at first be supposed. In reality, it only shows that the solution of the 
 ferrocyanide passes round to the opposite vein during this period, but 
 it does not necessarily follow that the entire blood moves with the 
 same rapidity ; since the injected saline solution may diffuse itself 
 through the blood, so as to travel faster than the blood itself. Sub- 
 sequent experiments of Poisseuille showed, in fact, that other sub- 
 stances injected at the same time may either accelerate or retard the 
 movement of the ferrocyanide. If a little nitrate of potass, for 
 example, were injected together with the ferrocyanide, the latter 
 salt appeared in the blood flowing from the opposite jugular at the 
 end of twenty seconds. A solution of acetate of ammonia, again, 
 shortened the period to eighteen seconds. On the other hand, a 
 little alcohol, injected at the same time, retarded its motion to such 
 a degree, that the ferrocyanide could not be detected till the end of 
 
 ' Physical Phenomena of Living Beings, Pereira's translation, Philada. ed , 1848, 
 p. 317. 
 
262 THE CIECULATION. 
 
 forty to forty-five seconds. These facts show conclusively that the 
 time required for a solution of ferrocyanide of potassium to appear 
 in the opposite jugular vein does not depend altogether on the rate 
 of movement of the blood itself, but is influenced very considerably 
 by the chemical constitution and physical properties of the injected 
 fluid, and its physical relations to the blood and to the walls of the 
 bloodvessels. Furthermore, we have already seen that the different 
 ingredients of the blood do not all circulate with the same rapidity. 
 In a microscopic examination, for example, it is evident that the 
 white globules of the blood move much more slowly than the red; 
 and it is very possible that the red globules themselves pass less 
 rapidly from one point to another than those portions of the blood 
 which are entirely fluid. 
 
 The truth is, however, that we cannot fix upon any uniform rate 
 which shall express exactly the time required by the entire blood 
 to pass the round of the whole vascular system, and return to a 
 given point. The circulation of the blood, far from being a simple 
 phenomenon, like a current of water through a circular tube, is, 
 on the contrary, extremely complicated in all its anatomical and 
 physiological conditions; and it differs in rapidity, as well as in its 
 physical and chemical phenomena, in different parts of the circu- 
 latory apparatus. We have already seen how much the form of 
 the capillary plexus varies in different organs. In some the vascu- 
 lar network is close, in others comparatively open. In some its 
 meshes are circular in shape, in others polygonal, in others rectan- 
 gular. In some the vessels are arranged in twisted loops, in others 
 they communicate by irregular but abundant inosculations. The 
 mere distance at which an organ is situated from the heart must 
 modify to some extent the time required for its blood to return 
 again to the centre of the circulation. The blood which passes 
 through the coronary arteries, for example, and the capillaries of 
 the heart itself, must be returned to the right auricle in a compara- 
 tively short time ; while that which is carried by the carotids into 
 the capillary system of the head and neck, to return by the jugulars, 
 will require a longer interval. That, again, which descends by the 
 abdominal aorta and its divisions, to the lower extremities, and 
 which, after circulating through the tissues of the leg and foot, 
 mounts upward through the whole course of the saphena, femoral, 
 iliac and abdominal veins, must be still, longer on its way ; while 
 that which circulates through the abdominal digestive organs and 
 is then collected by the portal system, to be again dispersed through 
 
LOCAL VARIATIONS. 263 
 
 the glandular tissue of the liver, requires undoubtedly a longer 
 period still to perform its double capillary circulation. The blood, 
 therefore, arrives at the right side of the heart, from different parts 
 of the body, at successive intervals; and may pass several times 
 through one organ while performing a single circulation through 
 another. 
 
 Furthermore, the chemical phenomena taking place in the blood 
 and the tissues vary to a similar extent in different organs. The 
 actions of transformation and decomposition, of nutrition and secre- 
 tion, of endosmosis and exosmosis, which go on simultaneously 
 throughout the body, are yet extremely varied in their character, 
 and produced a similar variation in the phenomena of the circula- 
 tion. In one organ the blood loses more fluid than it absorbs ; in 
 another it absorbs more than it loses. The venous blood, conse- 
 quently, has a different composition as it returns from different 
 organs. In the brain and spinal cord it gives up those ingredients 
 necessary for the nutrition of the nervous matter, and absorbs cho- 
 lesterine and other materials resulting from its waste; in the muscles 
 it loses those substances necessary for the supply of the muscular 
 tissue, and in the bones those which are requisite for the osseous 
 system. In the parotid gland it yields the ingredients of the saliva; 
 in the kidneys, those of the urine. In the intestine it absorbs in 
 large quantity the nutritious elements of the digested food ; and in 
 the liver, gives up substances destined finally to produce the bile, 
 at the same time that it absorbs sugar, which has been produced 
 in the hepatic tissue. In the lungs, again, it is the elimination of 
 carbonic acid and the absorption of oxygen that constitute its prin- 
 cipal changes. It has been already remarked that the temperature 
 of the blood varies in different veins, according to the peculiar 
 chemical and nutritive changes going on in the organs from which 
 they originate. Its color, even, which is also dependent on the 
 chemical and nutritive actions taking place in the capillaries, varies 
 in a similar manner. In the lungs, it changes from blue to red ; 
 in the capillaries of the general system, from red to blue. But its 
 tinge also varies very considerably in different parts of the general 
 circulation. The blood of the hepatic veins is darker than that of 
 the femoral or brachial vein. In the renal veins it is very much 
 brighter than in the vena cava; and when the circulation through 
 the kidneys is free, the blood returning from them is nearly as red 
 as arterial blood. 
 
 We must regard the circulation of the blood, therefore, not as a 
 
264 
 
 THE CIRCULATION. 
 
 simple process, but as made up of many different circulations, going 
 on simultaneously in different organs. It has been customary to 
 
 illustrate it, in diagram, by a double 
 circle, or figure of 8, of which the 
 upper arc is used to represent the 
 pulmonary, the lower the general cir- 
 culation. This, however, gives but a 
 very imperfect idea of the entire cir- 
 culation, as it really takes place. It 
 would be much more accurately re- 
 presented by such a diagram as that 
 given in Fig. 101, in which its varia- 
 tions in different parts of the body are 
 indicated in such a manner as to show, 
 in some degree, the complicated cha- 
 racter of its phenomena. The circula- 
 tion is modified in these different parts, 
 not only in its mechanism, but also in 
 its rapidity and quantity, and in the 
 nutritive functions performed by the 
 blood. In one part, it stimulates the 
 nervous centres and the organs of 
 special sense; in others it supplies the 
 fluid secretions, or the ingredients of 
 the solid tissues. One portion, in 
 passing through the digestive appara- 
 tus, absorbs the materials requisite 
 for the nourishment of the body ; an- 
 other, in circulating through the lungs, 
 exhales the carbonic acid which it has 
 accumulated elsewhere, and absorbs 
 the oxygen which is afterward trans- 
 ported to distant tissues by the current 
 of arterial blood. The phenomena of 
 the circulation are even liable, as we 
 have already seen, to periodical va- 
 riations in the same organ; increas- 
 ing or diminishing in intensity with 
 the condition of rest or activity of 
 the whole body, or of the particular 
 organ which is the subject of observation. 
 
 Diagram of the Circulation. — 1. 
 Heart. 2. Lungs. 3. Head and upper 
 extremities. 4. Spleen. 5. Intestine. 6. 
 Kidney. 7. Lower extremities. 8 Liver. 
 
SECRETION. 265 
 
 CHAPTER XV. 
 
 SECRETION. 
 
 We have already seen, in the last chapter, how the elements of 
 the blood are absorbed by the tissues during the capillary circula- 
 tion, and assimilated by them or converted into their own substance. 
 In this process, the inorganic or saline matters are mostly taken up 
 unchanged, and are merely appropriated by the surrounding parts in 
 particular quantities ; while the organic substances are transformed 
 into new compounds, characteristic of the dififerent tissues by which 
 they are assimilated. In this way the various tissues of the body, 
 though they have a diiferent chemical composition from the blood, 
 are nevertheless supplied by it with appropriate ingredients, and 
 their nutrition constantly maintained. 
 
 Beside this process, which is known by the name of " assimila- 
 tion," there is another somewhat similar to it, which takes place in 
 the different glandular organs, known as the process of secretion. It 
 is the object of this function to supply certain fluids, differing in 
 chemical constitution from the blood, which are required to assist 
 in various physical and chemical actions going on in the body. 
 These secreted fluids, or "secretions," as they are called, vary in 
 consistency, density, color, quantity, and reaction. Some of them 
 are thin and watery, like the tears and the perspiration ; others are 
 viscid and glutinous, like mucus and the pancreatic fluid. They 
 are alkaline like the saliva, acid like the gastric juice, or neutral 
 like the bile. Each secretion contains water and the inorganic salts 
 of the blood, in varying proportions; and is furthermore distin- 
 guished by the presence of some peculiar animal substance which 
 does not exist in the blood, but which is produced by the secreting 
 action of the glandular organ. As the blood circulates through the 
 capillaries of the gland, its watery and saline constituents transude 
 in certain quantities, and are discharged into the excretory duct. 
 At the same time, the glandular cells, which have themselves been 
 nourished by the blood, produce a new substance by the catalytic 
 
266 SECRETION. 
 
 transformation of their organic constituents; and this new substance 
 is discharged also into the excretory duct and mingled with the 
 other ingredients of the secreted fluid. A true secretion, therefore, 
 is produced only in its own particular gland, and cannot be formed 
 elsewhere, since the glandular cells of that organ are the only 
 ones capable of producing its most characteristic ingredient. Thus 
 pepsine is formed only in the tubules of the gastric mucous mem- 
 brane, pancreatine only in the pancreas, tauro-cholate of soda only 
 in the liver. 
 
 One secreting gland, consequently, can never perform vicariously 
 the office of another. Those instances which have been from time 
 to time reported of such an unnatural action are not, properly 
 speaking, instances of "vicarious secretion;" but only cases in 
 which certain substances, already existing in the blood, have made 
 their appearance in secretions to which they do not naturally belong. 
 Thus cholesterine, which is produced in the brain and is taken up 
 from it by the blood, usually passes out with the bile ; but it may 
 also appear in the fluid of hydrocele, or in inflammatory exuda- 
 tions. The sugar, again, which is produced in the liver and taken 
 up by the blood, when it accumulates in large quantity in the cir- 
 culating fluid, may pass out with the urine. The coloring matter 
 of the bile, in cases of biliary obstruction, may be reabsorbed, and 
 so make its appearance in the serous fluids, or even in the perspira- 
 tion. In these instances, however, the unnatural ingredient is not 
 actually produced by the kidneys, or the perspiratory glands, but 
 is merely supplied to them, already formed, by the blood. Cases 
 of *' vicarious menstruation" are simply capillary hemorrhages 
 which take place from various mucous membranes, owing to the 
 general disturbance of the circulation in amenorrhcea. A true 
 secretion, however, is always confined to the gland in which it 
 naturally originates. 
 
 The force by which the different secreted fluids are. prepared in 
 the glandular organs, and discharged into their ducts, is a peculiar 
 one, and resident only in the glands themselves. It is not simply 
 a process of filtration, in which the ingredients of the secretion 
 exude from the bloodvessels by exosmosis under the influence of 
 pressure ; since the most characteristic of these ingredients, as we 
 have already mentioned, do not pre-exist in the blood, but are 
 formed in the substance of the gland itself. Substances, even, 
 which already exist in the blood in a soluble form, may not have 
 the power of passing out through the glandular tissue. Bernard 
 
SECRETION. 267 
 
 has found' that ferrocjanide of potassium, when injected into the 
 jugular vein, though it appears with great facility in the urine, 
 does not pass out with the saliva; and even that a solution of 
 the same salt, injected into the duct of the parotid gland, is ab- 
 sorbed, taken up by the blood, and discharged with the urine ; but 
 does not appear in the saliva, even of the gland into which it has 
 been injected. The force with which the secreted fluids accumulate 
 in the salivary ducts has also been shown by Ludwig's experi- 
 ments'* to be sometimes greater than the pressure in the bloodves- 
 sels. This author found, by applying mercurial gauges at the same 
 time to the duct of Steno and to the artery of the parotid gland, that 
 the pressure in the duct from the secreted saliva was considerably 
 greater than that in the artery from the circulating blood ; so that 
 the passage of the secreted fluids had really taken place in a direc- 
 tion contrary to that which would have been caused by the simple 
 influence of pressure. 
 
 The process of secretion, therefore, is one which depends upon 
 the peculiar anatomical and chemical constitution of the glandular 
 tissue and its secreting cells. These cells have the property of 
 absorbing and transmitting from the blood certain inorganic and 
 saline substances, and of producing, by chemical metamorphosis, 
 certain peculiar animal matters from their own tissue. These sub- 
 stances are then mingled together, dissolved in the watery fluids 
 of the secretion, arud discharged simultaneously by the excretory 
 duct. 
 
 All the secreting organs vary in activity at different periods. 
 Sometimes they are nearly at rest ; while at certain periods they 
 become excited, under the influence of an occasional or periodical 
 stimulus, and then pour out their secretion with great rapidity and in 
 large quantity. The perspiration, for example, is usually so slowly 
 secreted that it evaporates as rapidly as it is poured out, and the 
 surface of the, skin remains dry; but under the influence of unusual 
 bodily exercise or mental excitement it is secreted much faster 
 than it can evaporate, and the whole integument becomes covered 
 with moisture. The gastric juice, again, in the intervals of digestion 
 is either not secreted at all, or is produced in a nearly inappreciable 
 quantity ; but on the introduction of food into the stomach, it is 
 immediately poured out in such abundance, that between two and 
 three ounces may be collected in a quarter of an hour. 
 
 ' Lecjons de Physiologie ExiJerimentale. Paris, 1856, tome ii. p. 96, et seq. 
 2 Ibid , p. 106. 
 
268 SECRETION. 
 
 « 
 
 The principal secretions met with in the animal body are as 
 follows : — 
 
 1. Mucus. 6. Saliva. 
 
 2. Sebaceous matter. 7. Gastric juice. 
 
 3. Perspiration. 8. Pancreatic juice. 
 
 4. The tears. 9. Intestinal juice. 
 
 5. The milk. 10. Bile. 
 
 The last five of these fluids have already been described in the 
 preceding chapters. We shall therefore only require to examine 
 at present the five following, viz., mucus, sebaceous matter, per- 
 spiration, the tears, and the milk, together with some peculiarities 
 in the secretion of the bile. 
 
 1. Mucus. — Nearly all the mucous membranes are provided with 
 follicles or glandulas, in which the mucus is prepared. These folli- 
 cles are most abundant in the lining membrane of the mouth, nares, 
 pharynx, oesophagus, trachea and bronchi, vagina, and male urethra. 
 They are generally of a compound form, consisting of a number of 
 secreting sacs or cavities, terminating at one end in a blind ex- 
 tremity, and opening by the other into a common diict by which 
 the secreted fluid is discharged. Each ultimate secreting sac or 
 follicle is lined with glandular epithelium (Fig. 102), and surround- 
 ed on its external surface by a network of capillary bloodvessels. 
 These vessels, penetrating deeply into the 
 interstices between the follicles, bring the 
 blood nearly into contact with the epithelial 
 cells lining its cavity. It is these cells 
 which prepare the secretion, and discharge 
 it afterward into the commencement of the 
 „ excretory duct. 
 
 Follicles of a Com- J 
 
 POUND Mucous Glandule. The mucus, produccd in the manner 
 
 From the human subject. (After ., -i ., ■, . , ,, n • ^ 
 
 K;3iiiker.)_a. Membrane of the . ^bovc dcscribcd, IS a clcar, colorlcss fluid, 
 follicle, h, c. Epithelium of the which is pourcd out in larger or smaller 
 quantity on the surface of the mucous 
 membranes. It is distinguished from other secretions by its vis- 
 cidity, which is its most marked physical property, and which 
 depends on the presence of a peculiar animal matter, known under 
 the name of mucosine. When unmixed with other animal fluids, 
 this viscidity is so great that the mucus has nearly a semi-solid or 
 gelatinous consistency. Thus, the mucus of the mouth, when ob- 
 tained unmixed with the secretions of the salivary glands, is so 
 
SEBACEOUS MATTER. 269 
 
 tougli and adhesive that the vessel containing it may be turned 
 upside down without its running out. The mucus of the cervix 
 uteri has a similar firm consistency, so as to' block up the cavity 
 of this part of the organ with a semi-solid gelatinous mass. Mucus 
 is at the same time exceedingly smooth and slippery to the touch, 
 so that it lubricates readily the surfaces upon which it is exuded, 
 and facilitates the passage of foreign substances, while it defends 
 the mucous membrane itself from injury. 
 
 The composition of mucus, according to the analyses of Nasse,^ 
 is as follows : — 
 
 Composition of Pulmonary Mucus. 
 
 Water 955.52 
 
 Animal matter .......... 33.57 
 
 Fat 2.89 
 
 Chloride of sodium ......... 5.83 
 
 Phosphates of soda and potass ...... 1.05 
 
 Sulphates " " 0.65 
 
 Carbonates " " 0.49 
 
 1000.00 
 
 The animal matter of mucus is insoluble in water ; and conse- 
 quently mucus, when dropped into water, does not mix with it, but 
 is merely broken up by agitation into gelatinous threads and flakes, 
 which subside after a time to the bottom. It is miscible, however, 
 to some extent, with other animal fluids, and may be incorporated 
 with them, so as to become thinner and more dilute. It readily 
 takes on putrefactive changes, and communicates them to other 
 organic substances with which it may be in contact. 
 
 The varieties of mucus found in different parts of the body are 
 probably not identical, but differ a little in the character of their 
 principal organic ingredient, as well as in the proportions of their 
 saline constituents. The function of mucus is for the most part a 
 physical one, viz., to lubricate the mucous surfaces, to defend them 
 from injury, and to facilitate the passage of foreign substances 
 through their cavities. 
 
 2. Sebaceous Matter, — The sebaceous matter is distinguished 
 by containing a very large proportion of fatty or oily ingredients. 
 There are three varieties of this secretion met with in the body, 
 viz., one produced by the sebaceous glands of the skin, another 
 by the ceruminous glands of the external auditory meatus, and 
 a third by the Meibomian glands of the eyelid. The sebaceous 
 
 ' Simon's Chemistry of Man, Philada., 1846, p. 352. 
 
270 SECRETION. 
 
 glands of the skin are found most abundantly in those parts which 
 are thickly covered with hairs, as well as on the face, the labia 
 minora of the female generative organs, the glans penis, and the 
 prepuce. They consist sometimes of a simple follicle, or flask- 
 shaped cavity, opening by a single orifice ; but more frequently of 
 a number of such follicles grouped round a common excretory duct. 
 The duct nearly always opens just at the root of one of the hairs, 
 
 which is smeared more or less abundantly 
 Fig- 103. with its secretion. Each follicle, as in the 
 
 case of the mucous glandules, is lined 
 with epithelium, and its cavity is filled 
 
 yi^^ .i'"'^^*f^^^B ^^^'^ ^^ secreted sebaceous matter. 
 "?^'^'»"^V- .^^H In the Meibomian glands of the eye- 
 
 pf '-'>- '^^*"'^^B lid (Fig. 103), the follicles are ranged 
 ''.. ,- :' " ^^H along the sides of an excretory duet, 
 y, ,. '-'"i ' . ^^^H situated just beneath the conjunctiva, on 
 |'£? ;' .1 '^'^'''^^B th® posterior surface of the tarsus, and 
 >' "^ '"^ "* i^^l opening upon its free edge, a little be- 
 l^iiRJI^ffli^^H ^i^d *^® roots of the eyelashes. The 
 ceruminous glands of the external audi- 
 tory meatus, again, have .the form of long 
 tubes, which terminate, at the lower part 
 
 Meibomian Glands, after o ^ • t • i 
 
 Liidovic. 01 the integument Iming the meatus, in 
 
 a globular coil, or convolution, covered 
 externally by a network of capillary bloodvessels. 
 
 The sebaceous matter of the skin has the following composition, 
 according to Esenbeck.' 
 
 Composition of Sebaceous Mattek. 
 
 Animal substances ....... 358 
 
 Fatty matters ........ 868 
 
 Phosphate of lime ........ 200 
 
 Carbonate of lime ........ 21 
 
 Carbonate of magnesia ....... 16 
 
 Chloride of sodium ^ 
 
 I . ■ 37 
 Acetate of soda, &c. j • • • • • • 
 
 1000 
 
 Owing to the large proportion of stearine in the fatty ingredients 
 of the sebaceous matters, they have a considerable degree of con- 
 sistency. Their office is to lubricate the integument and the hairs, 
 to keep them soft and pliable, and to prevent their drying up by 
 
 ' Simon's Chemistry of Man, p. 379. 
 
PEESPIRATION. 
 
 271 
 
 too rapid evaporation. Wlien the sebaceous glands of the scalp 
 are inactive or atrophied, the hairs become dry and brittle, are 
 easily split or broken off, and finally cease growing altogether. 
 The ceruminous matter of the ear is intended without doubt partly 
 to obstruct the cavity of the meatus, and by its glutinous consist- 
 ency and strong odor to prevent small insects from accidentally 
 introducing themselves into the meatus. The secretion of the 
 Meibomian glands, by being smeared on the edges of the eyelids, 
 prevents the tears from running over upon the cheeks, and confines 
 them within the cavity of the lachrymal canals. 
 
 Fiff. 104. 
 
 3. Perspiration. — The perspiratory glands of the skin are 
 scattered everywhere throughout the integument, being most 
 abundant on the anterior portions of the body. They consist each 
 of a slender tube, about -^l^ of an inch in diameter, lined with 
 glandular epithelium, which penetrates nearly through the entire 
 thickness of the skin, and terminates below in a globular coil, very 
 similar in appearance to that of 
 the ceruminous glands of the ear. 
 (Fig. 104.) A network of capil- 
 lary vessels envelops the tubular 
 coil and supplies the gland with 
 the materials necessary to its se- 
 cretion. 
 
 These glands are very abundant 
 in some parts. On the posterior 
 portion of the trunk, the cheeks, 
 and the skin of the thigh and leg 
 there are, according to Krause,* 
 about 500 to the square inch ; on 
 the anterior part of the trunk, the 
 forehead, the neck, the forearm, 
 and the back of the hand and foot 
 1000 to the square inch ; and on the 
 sole of the foot and the palm of the hand about 2700 in the same 
 space. According to the same observer, the whole number of per- 
 spiratory glands is not less than 2,300,000, and the length of each 
 tubular coil, when unravelled, about y'g of an inch. The entire 
 length of the glandular tubing must therefore be not less than 
 153,000 inches, or about two miles and a half. 
 
 A Perspiratory Gland, -with its ves- 
 sels ; magnified 35 times. (After Todd and Bow- 
 man.) — a. Glandular coil. 6. Plexus of vessels, 
 c. Excretory duct. 
 
 Kcilliker, Handbucli der Gewebelelire, Leipzig, 1852, p. 147. 
 
272 SECEETioisr. 
 
 It is easy to understand, therefore, that a very large quantity of 
 fluid may be supplied from so extensive a glandular apparatus. It 
 results from the researches of Lavoisier and Seguin^ that the ave- 
 rage quantity of fluid lost by cutaneous perspiration during 24 
 hours is 18,770 grains, or nearly two pounds avoirdupois. A still 
 larger quantity than this may be discharged during a shorter time, 
 when the external temperature is high and the circulation active. 
 Dr. Southwood Smith^ found that the laborers employed in gas 
 works lost sometimes as much as 3 J pounds' weight, by both cata- 
 neous and pulmonary exhalation, in less than an hour. In these 
 cases, as Seguin has shown, the amount of cutaneous transpiration 
 is about twice as great as that which takes place through the lungs. 
 
 The perspiration is a colorless watery fluid, generally with a 
 distinctly acid reaction, and > having a peculiar odor, which varies 
 somewhat according to the part of the body from which the speci- 
 men is obtained. Its chemical constitution, according to Anselmino.^ 
 is as follows : — 
 
 C'JIPOSITION OF THE PeKSPIBATION. 
 
 Water 995.00 
 
 Animal matters, with lime ........ .10 
 
 Sulphates, and substances soluble in water .... 1.05 
 
 Chlorides of sodium and potassium, and spirit-extract . . 2.40 
 
 Acetic acid, acetates, lactates, and alcohol-extract . . . 1.45 
 
 1000.00 
 
 The office of the cutaneous perspiration is principally to regulate 
 the temperature of the body. We have already seen, in a preced- 
 ing chapter, that the living body will maintain the temperature of 
 100° F., though subjected to a much lower temperature by the 
 surrounding atmosphere, in consequence of the continued genera- 
 tion of heat which takes place in its interior ; and that if, by long 
 continued or severe exposure, the blood become cooled down much 
 below its natural standard, death inevitably results. But the body 
 has also the power of resisting an unnaturally high temperature, 
 as well as an unnaturally low one. If exposed to the influence of 
 an atmosphere warmer than 100° F., the body does not become 
 heated up to the temperature of the air, but remains at its natural 
 standard. This is provided for by the action of the cutaneous 
 glands, which are excited to unusual activity, and pour out a large 
 quantity of watery fluid upon the skin. This fluid immediately 
 
 ' Robin and Verdeil. Op. cit., vol. ii. p. 145. 
 ^ Philosophy of Health, London, 1838, chap. xiii. 
 ^ Simon. Op. cit., p. 374. 
 
THE TEARS. 273 
 
 evaporates, and in assuming the gaseous form causes so much heat 
 to become latent that the cutaneous surfaces are cooled down to 
 their natural temperature. 
 
 . So long as the air is dry, so that evaporation from the surface 
 can go on rapidly, a very elevated temperature can be borne with 
 impunity. The workmen of the sculptor Chantrey were in the 
 habit, according to Dr. Carpenter, of entering a furnace in which 
 the air was heated up to 350°; and other instances have been known 
 in which a temperature of 400° to 600° has been borne for a time 
 without much inconvenience. But if the air be saturated with 
 moisture, and evaporation from the skin in this way retarded, the 
 body soon becomes unnaturally warm ; and if the exposure be long 
 continued, death is the result. It is easily seen that horses, when 
 fast driven, suffer much more from a warm and moist atmosphere 
 than from a warm and dry one. The experiments of Magendie and 
 others have shown' that quadrupeds confined in a dry atmosphere 
 suffer at first but little inQonvenience, even when the temperature 
 is much above that of their own bodies ; but as soon as the atmo- 
 sphere is loaded with moisture, or the supply of perspiration is ex- 
 hausted, the blood becomes heated, and the animal dies. Death 
 follows in these cases as soon as the blood has become heated up to 
 8° or 9° F., above its natural standard. The temperature of 110°, 
 therefore, which is the natural temperature of birds, is fatal to quad- 
 rupeds ; and we have found that frogs, whose natural temperature 
 is 50° or 60°, die very soon if they are kept in water at 100° F. 
 
 The amount of perspiration is liable to variation, as we have 
 already intimated, from the variations in temperature of the sur- 
 rounding atmosphere. It is excited also by unusual muscular 
 exertion, and increased or diminished by various nervous condi- 
 tions, such as anxiety, irritation, lassitude, or excitement. 
 
 4. The Tears. — The tears are produced by lobulated glands 
 situated at the upper and outer part of the orbit of the eye, and 
 opening, by from six to twelve ducts, upon the surface of the con- 
 junctiva, in the fold between the eyeball and the outer portion of 
 the upper lid. The secretion is extremely watery in its composition, 
 and contains only about one part per thousand of solid matters, 
 consisting mostly of chloride of sodium and animal extractive 
 matter. The office of the lachrymal secretion is simply to keep the 
 
 ' Bernard, Lectures on the Blood. Atlee's translation, p. 25. 
 
 lb 
 
274 
 
 SECRETION. 
 
 surfaces of the cornea and conjunctiva moist and polished, and to 
 preserve in this way the transparency of the parts. The tears, 
 which are constantly secreted, are spread out uniformly over the 
 anterior part of the eyeball by the movement of the lids in wink- 
 ing, and are gradually conducted to the inner angle of the eye. 
 Here they are taken up by the puncta lachrymalia, pass through 
 the lachrymal canals, and are finally discharged into the nasal pas- 
 sages beneath the inferior turbinated bones. A constant supply of 
 fresh fluid is thus kept passing over the transparent parts of the 
 eyeball, and the bad results avoided Avhich would follow from its 
 accumulation and putrefactive alteration. 
 
 5. The Milk. — The mammary glands are conglomerate glands, 
 resembling closely in their structure the pancreas, the salivary, and 
 the lachrymal glands. They consist of numerous secreting sacs or 
 follicles, grouped together in lobules, each lobule being supplied 
 with a common excretory duct, which joins those coming from 
 
 adjacent parts of the gland. 
 (Fig. 105.) In this way, by 
 their successive union, they 
 form larger branches and 
 trunks, until they are reduced 
 in numbers to some 15 or 20 
 cylindrical ducts, the lactife- 
 rous ducts, which open finally 
 by as many minute orifices 
 upon the extremity of the 
 nipple. 
 
 The secretion of the milk 
 becomes fairly established at 
 the end of ^two or three days 
 after delivery, though the 
 breasts often contain a milky 
 fluid during the latter part of pregnancy. At first, the fluid dis- 
 charged from the nipple is a yellowish turbid mixture, which is 
 called the colostrum. It has the appearance of being thinner than 
 the milk, but chemical examinations have shown' that it really con- 
 tains a larger amount of solid ingredients than the perfect secre- 
 tion. When examined under the microscope it is seen to contain, 
 beside the milk-globules proper, a large amount of irregularly glo- 
 
 Gi.ANDULAR Structure of Mamma. 
 
 ' Lehmann, op. cit., vol. ii. p. 63. 
 
THE MILK. 
 
 275 
 
 bular or oval bodies, from y^^-go to ^^^ of an inch in diameter, 
 which are termed the *' colostrum corpuscles." (B'ig. 106.) These 
 bodies are more yellow and 
 opaque than the true milk- 
 globules, as well as being very 
 much larger. They have a 
 well defined outline, and con- 
 sist apparently of a group of 
 minute oily granules or glo- 
 bules, imbedded in a mass 
 of organic substance. The 
 milk-globules at this time 
 are less abundant than after- 
 ward, and of larger size, 
 measuring mostly from ^^'^^ 
 
 to Ys'oo o^ ^^ ^^^^ ^^ ^'^' 
 meter. 
 
 At the end of a day or 
 two from its first appearance 
 
 the colostrum ceases to be discharged, and is replaced by the true 
 milky secretion. 
 
 The milk, as it is discharged from the nipple, is a white, opaque 
 fluid, with a slightly alkaline reaction, and a specific gravity of 
 about 1030. Its proximate chemical constitution, according to 
 Pereira and Lehmann, is as follows : — 
 
 Composition of Cow's Milk. 
 
 . . . 9,1^.2 
 
 44.8 
 
 31.3 
 
 47.7 
 
 1 
 
 Chlorides of sodium and potassium ..... 
 
 Phosphates of soda and potass ...... i 
 
 Pliosphate of lime 
 
 " " magnesia 
 " " iron 
 Alkaline carbonates . 
 
 Colostrum Corpuscles, with milk-globules ; 
 from a woman, one day after delivery. 
 
 Water 
 Casein 
 Butter 
 Sugar 
 Soda 
 
 6.0 
 
 1000.0 
 
 Human milk is distinguished from the above by containing less 
 casein, and a larger proportion of oily and saccharine ingredients. 
 The entire amount of solid ingredients is also somewhat less than 
 in cow's milk. 
 
276 
 
 SECRETION. 
 
 The casein is one of the most important ingredients of the milk. 
 It is an extremely nutritious, organic substance, which is held in a 
 fluid form by union with the water of the secretion. Casein is not 
 coagulable by heat, and, consequently, milk may be boiled without 
 changing its consistency to any considerable extent. It becomes 
 a little thinner and more fluid during ebullition, owing to the melt- 
 ing of its oleaginous ingredients ; and a thin, membranous film 
 forms upon its surface, consisting probably of a very little albumen 
 which the milk contains, mingled with the casein. The addition of 
 any of the acids, however, mineral, animal, or vegetable, at once 
 coagulates the casein, and the milk becomes curdled. Milk is 
 coagulated, furthermore, by the gastric juice in the natural process 
 of digestion, immediately after being taken into the stomach ; and 
 if vomiting occur soon after a meal containing milk, it is thrown 
 off in the form of semi-solid, curd-like flakes. 
 
 The mucous membrane of the calves' stomach, or rennet, also 
 has the power of coagulating casein ; and when milk has been 
 curdled in this way, and its watery, saccharine, and inorganic in- 
 gredients separated by mechanical pressure, it is converted into 
 cheese. The peculiar flavor of the different varieties of cheese 
 depends on the quantity and quality of the oleaginous ingredients 
 which have been entangled with the coagulated casein, and on the 
 
 alterations which these sub- 
 Fig. 107. stances have undergone by 
 the lapse of time and ex- 
 posure to the atmosphere. 
 
 The sugar and saline sub- 
 stances of the milk are in 
 solution, together with the 
 casein and water, forming a 
 clear, colorless, homogene- 
 ous, serous fluid. The but- 
 ter, or oleaginous ingredient, 
 however, is suspended in 
 this serous fluid in the form 
 of minute granules and 
 globules, the true "milk 
 globules." (Fig. 107.) These 
 globules are nearly fluid at 
 th3 temperature of the body, and have a perfectly circular out- 
 line. In the perfect milk, they are very much more abundant and 
 
 ?o°o o°o? O.oo, 
 o 
 
 o°» 
 
 @:J&ro^L 
 
 a o 
 
 o°o 
 
 ^ol^.'o 
 
 " Oo 
 
 'O O ^ O O"^ 
 oooo O O o^ o'oo °oO 
 
 bPoOO ZoOo - 
 
 - o 
 
 Milk-Globules; from same woman as above, 
 four days after delivery. Secretion fully established. 
 
THE MILK. 277 
 
 smaller in size than in the colostrum; as the largest of them are 
 
 not over v^^V^ of an inch in diameter, and the greater number 
 
 about YxrrriyTT of an inch. 
 
 The following is the composition of the butter of cow's milk, 
 
 according to Eobin and Verdeil: — 
 
 Margarine . . . . . . . . . .68 
 
 Oleine 30 
 
 Butyrine .......... 2 
 
 100 
 
 It is the last of these ingredients, the butyrine, which gives the 
 peculiar flavor to the butter of milk. 
 
 The niilk-globules have sometimes been described as if each one 
 were separately covered with a thin layer of coagulated casein or 
 albumen. No such investing membrane, however, is to be seen. 
 The milk-globules are simply small masses of semi-fluid fat, sus- 
 pended by admixture in the watery and serous portions of the 
 secretion, so as to make an opaque, whitish emulsion. They do 
 not fuse together when they come in contact under the microscope, 
 simply because they are not quite fluid, but contain a large pro- 
 portion of margarine, which is solid at ordinary temperatures of 
 the body, and is only retained in a partially fluid form by the 
 oleine with which it is associated. The globules may be made to 
 fuse with each other, however, by simply heating the milk and 
 subjecting it to gentle pressure between two slips of glass. 
 
 "When fresh milk is allowed to remain at rest for twelve to twenty- 
 four hours, a large portion of its fatty matters rise to the surface, 
 and form there a dense and rich looking yellowish-white layer, the 
 cream, which may be removed, leaving the remainder still opaline, 
 but less opaque than before. At the end of thirty-six to forty-eight 
 hours, if the weather be warm, the casein begins to take on a 
 putrefactive change. In this condition it exerts a catalytic action 
 upon the other ingredients of the milk, and particularly upon the 
 sugar. A pure watery solution of milk-sugar {C^^S.^/)^) may be 
 kept for an indefinite length of time, at ordinary temperatures, 
 without undergoing any change. But if kept in contact with the 
 partially altered casein, it suffers a catalytic transformation, and is 
 converted into lactic acid (CgHgOg). This unites with the free soda, 
 and decomposes the alkaline carbonates, forming lactates of soda 
 and potass. After the neutralization of these substances has been 
 accomplished, the milk loses its alkaline reaction and begins to turn 
 sour. The free lactic acid then coagulates the casein, and the milk 
 
278 SECRETION. 
 
 is curdled. The altered organic matter also acts upon the oleagi- 
 nous ingredients, which are partly decomposed; and the milk 
 begins to give off a rancid odor, owing to the development of 
 various volatile fatty acids, among which are butyric acid, and the 
 like. These changes are very much hastened by a moderately 
 elevated temperature, and also by a highly electric state of the 
 atmosphere. 
 
 The production of the milk, like that of other secretions, is liable 
 to be much influenced by nervous impressions. It may be increased 
 or diminished in quantity, or vitiated in quality by sudden emo- 
 tions ; and it is even said to have been sometimes so much altered 
 in this way as to produce indigestion, diarrhoea, and convulsions in 
 the infant. 
 
 Simon found' that the constitution of the milk varies from day to 
 day, owing to temporary causes ; and that it undergoes also more 
 permanent modifications, corresponding with the age of the infant. 
 He analyzed the milk of a nursing woman during a period of nearly 
 six months, commencing with the second day after delivery, and 
 repeating his examinations at intervals of eight or ten days. It 
 appears, from these observations, that the casein is at first in small 
 quantity ; but that it increases during the first two months, and 
 then attains a nearly uniform standard. The saline matters also 
 increase in a nearly similar manner. The sugar, on the contrary, 
 diminishes during the same period ; so that it is less abundant in 
 the third, fourth, fifth and sixth months, than it is in the first and 
 second. These changes are undoubtedly connected with the in- 
 creasing development of the infant, which requires a corresponding 
 alteration in the character of the food supplied to it. Finally, the 
 quantity of butter in the milk varies so much from day to day, 
 owing to incidental causes, that it cannot be said to follow any 
 regular course of increase or diminution. 
 
 6. Secretion of the Bile. — The anatomical peculiarities in the 
 structure of the liver are such as to distinguish it in a marked 
 degree from the other glandular organs. Its first peculiarity is 
 that it is furnished principally with venous blood. For, although 
 it receives its blood from the hepatic artery as well as from the 
 portal vein, the quantity of arterial blood with which it is supplied 
 is extremely small in comparison with that which it receives from 
 
 ' Op. cit., p. 337. 
 
SECRETION OF THE BILE. 
 
 279 
 
 the portal system. The blood which has circulated through the 
 capillaries of the stomach, spleen, pancreas, and intestine is collected 
 by the roots of the corresponding veins, and is discharged into the 
 great portal vein, which enters the liver at the great transverse 
 fissure of the organ. Immediately upon its entrance, the portal 
 vein divides into two branches, right and left, which supply the 
 corresponding portions of the liver ; and these branches success- 
 ively subdivide into smaller twigs and ramifications, until they are 
 reduced to the size, according to Kolliker, of ysVo of ^^ i^ch in 
 diameter. These veins, with their terminal branches, are now 
 arranged in such a manner as to include between them pentagonal 
 or hexagonal spaces, or portions of the hepatic substance g'g to Jg 
 of an inch in diameter in the human subject, which can readily be 
 distinguished by the naked eye, both on the exterior of the organ 
 and by the inspection of cut surfaces. The portions of hepatic 
 substance included in this way between the terminal branches of 
 the portal vein (Fig. 108) are 
 
 termed the " acini" or the Fig- 108. 
 
 "lobules" of the liver; and 
 the terminal venous branches, 
 occupying the spaces between 
 the adjacent lobules, are the 
 " interlobular" veins. In the 
 spaces between the lobules 
 we also find the minute 
 branches of the hepatic ar- 
 tery, and ,th e commencing 
 rootlets of the hepatic^ducts. 
 As the portal vein, the he- 
 patic artery, and the hepatic 
 duct enter the liver at the 
 
 n -I Ramification of Portal Ye IN in Livkk. — a. 
 
 transverse riSSUre, they are Twig of poital vein. &, 6. interlobular veins, c. Acini. 
 
 closely invested by a fibrous 
 
 sheath, Glisson's capsule, which accompanies them in their divisions 
 and ramifications. In some of the lower animals, as in the pig, 
 this sheath extends even to the interlobular spaces, inclosing each 
 lobule in a -thin fibrous investment, by which it is distinctly 
 separated from the neighboring parts. In the human subject, how- 
 ever, Glisson's capsule becomes gradually thinner as it penetrates 
 the liver, and disappears altogether before reaching the interlobular 
 spaces; so that here the lobules are nearly in contact with each 
 
280 SECEETION. 
 
 other by their adjacent surfaces, being separated only by the inter- 
 lobular veins and the minute branches «[' the hepatic artery and 
 duct previously mentioned. 
 
 From the sides of the interlobular veins, and also from their 
 terminal extremities, there are given oft' capillary vessels, which 
 penetrate the substance of each lobule and converge from its cir- 
 cumference toward its centre, inosculating at the same time freely 
 with each other, so as to form a minute vascular plexus, the " lobu- 
 lar" capillary plexus. (Fig. 109.) At the centre of each lobule, the 
 
 Fig. 109. 
 
 Lobule of Liver, showing distribution of bloodvessels; magnified 22 diameters — a, a. In- 
 terlobular veins. 6. Intralobular vein, c, c, c. Lobular capillary plexus, d, d. Twigs of inter- 
 lobular vein passing to adjacent lobules. 
 
 converging capillaries unite into a small vein (b), the " intralobu- 
 lar" vein, which is one of the commencing rootlets of the hepatic 
 vein. These rootlets, uniting successivelj'' with each other, so as 
 to form larger and larger branches, finally leave the liver at its 
 posterior edge, to empty into the ascending vena cava. 
 
 Beside the capillary bloodvessels of the lobular plexus, each 
 acinus is made up of an abundance of minute cellular bodies, about 
 T2V0 of an inch in diameter, the "hepatic cells." (Fig. 110.) These 
 cells have an irregularly pentagonal figure, and a soft consistency. 
 They are composed of a homogeneous organic substance, in the 
 midst of which are imbedded a large number of minute granules, 
 and generally several well defined oil-globules. There is also a 
 round or oval nucleus, with a nucleolus, imbedded in the substance 
 
SECRETION OF THE BILE. 
 
 281 
 
 of the cell, sometimes more or less obscured bj the granules and 
 oil drops with which it is surrounded. 
 
 The exact mode in which these cells are connected with the 
 hepatic duct was for a long time the most obscure point in the 
 minute anatomy of the liver. 
 
 It has now been ascertained, Fig. 110. 
 
 however, by the researches of 
 Dr. Leidy, of Philadelphia,' 
 and Dr. Beale, of London,^ 
 that they are really contained 
 in the interior of secreting 
 tubules, which pass off from 
 the smaller hepatic ducts, and 
 penetrate everywhere the 
 substance of the lobules. 
 The cells fill nearly or com- 
 pletely the whole cavity of 
 the tubules, and the tubules 
 themselves lie in close proxi- 
 mity with each other, so as 
 to leave no space between them except that which is occupied by 
 the capillary bloodvessels of the lobular plexus. 
 
 These cells are the active agents in accomplishing the function of 
 the liver. It is by their influence that the blood which is brought 
 in contact with them suffers certain changes which give rise to the 
 secreted products of the organ. The ingredients of the bile first 
 make their appearance in the substance of the cells. They are 
 then transuded from one to the other, until they are at last dis- 
 charged into the small biliary ducts seated in the interlobular 
 spaces. Each lobule of the liver must accordingly be regarded as 
 a mass of secreting tubules, lined with glandular cells, and invested 
 with a close network of capillary bloodvessels. It follows, there- 
 fore, from the abundant inosculation of the lobular capillaries, and 
 the manner in which they are entangled with the hepatic tissue, 
 that the blood, in passing through the circulation of the liver, 
 comes into the most intimate relation with the glandular cells of 
 the organ, and gives up to them the nutritious materials which are 
 afterward converted into the iuOTedients of the bile. 
 
 Hepatic Cells. From the human subject. 
 
 American Journal Med. Sci., January, 1848. 
 
 On Some Points in the Minute Anatomy of tlie Liver. 
 
 London, 1856. 
 
282 EXCKETION 
 
 CHAPTER XVI. 
 
 EXCRETION. 
 
 "We have now come to the last division of the great nutritive 
 function, viz., the process of excretion. In order to understand fairly 
 the nature of this process we must remember that all the component 
 parts of a living organism are necessarily in a state of constant 
 change. It is one of the essential conditions of their existence and 
 activity that they should go through with this incessant transforma- 
 tion and renovation of their component substances. Every living 
 animal and vegetable, therefore, constantly absorbs certain materials 
 from the exterior, which are modified and assimilated by the pro- 
 cess of nutrition, and converted into the natural ingredients of the 
 organized tissues. But at the same time with this incessant growth 
 and supply, there goes on in the same tissues an equally incessant 
 process of waste and decomposition. For though the elements of 
 the food are absorbed by the tissues, and converted into musculine, 
 osteine, haematine and the Hire, they do not remain permanently in 
 this condition, but almost immediately begin to pass over, by a con- 
 tinuance of the alterative process, into new forms and combinations, 
 which are destined to be expelled from the body, as others continue 
 to be absorbed. Thus Spallanzani and Edwards found that every 
 organized tissue not only absorbs oxygen from the atmosphere 
 and fixes it in its own substance; but at the same time exhales 
 carbonic acid, which has been produced by internal metamorphosis. 
 This process, by which the ingredients of the organic tissues, al- 
 ready formed, are decomposed and converted into new substances, 
 is called the process of Destructive Assimilation. 
 
 Accordingly we find that certain substances are constantly mak- 
 ing their appearance in the tissues and fluids of the body, which 
 did not exist there originally, and which have not been introduced 
 with the food, but which have been produced by the process of in- 
 ternal metamorphosis. These substances represent the waste, or 
 physiological detritus of the animal organism. They are the forms 
 
EXCRETION, 283 
 
 under wbich those materials present themselves, which have once 
 formed a part of the living tissues, but which have become altered 
 by the incessant changes characteristic of organized bodies, and 
 which are consequently no longer capable of exhibiting vital pro- 
 perties, or of performing the vital functions. They are, therefore, 
 destined to be removed and discharged from the animal frame, and 
 are known accordingly by the name oi Excrementitious Substances. 
 
 These excrementitious substances have peculiar characters by 
 which they may be distinguished from the other ingredients of the 
 living body; and they might, therefore, be made to constitute a 
 fourth class of proximate principles, in addition to the three which 
 we have enumerated in the preceding chapters. They are all sub- 
 stances of definite chemical composition, and all susceptible of 
 crystallization. Some of the most important of them contain nitro- 
 gen, while a few are non-nitrogenous in their composition. They 
 originate in the interior of living bodies, and are not found else- 
 where, except occasionally as the result of decomposition. They 
 are nearly all soluble in water, and are soluble without exception in 
 the animal fluids. They are formed in the substance of the tissues, 
 from which they are absorbed by the blood, to be afterward conveyed 
 by the circulating fluid to certain excretory organs, particularly the 
 kidneys, from which they are finally discharged and expelled from 
 the body. This entire process, made np of the production of the 
 excrementitious substances, their absorption by the blood, and their 
 final elimination, is known as the process of excretion. 
 
 The importance of this process to the maintenance of life is readily 
 shown by the injurious effects which follow upon its disturbance. 
 If the discharge of the excrementitious substances be in any way 
 impeded or suspended, these substances accumulate, either in the 
 blood or in the tissues or in both. In consequence of this retention 
 and accumulation, they become poisonous, and rapidly produce a 
 derangement of the vital functions. Their influence is principally 
 exerted upon the nervous system, through which they produce 
 most frequently irritability, disturbance of the special senses, deli- 
 rium, insensibility, coma, and finally death. The readiness with 
 which these effects are produced depends on the character of the 
 excrementitious substance, and the rapidity with whicli it is pro- 
 duced in the body. Thus, if the elimination of carbonic acid be 
 stopped, by overloading the atmosphere with an abundance of the 
 same gas, death takes place at the end of a few minutes ; but if the 
 elimination of urea by the kidneys be checked, it requires three or 
 
284 
 
 EXCRETION. 
 
 four days to produce a fatal result. A fatal result, however, is cer- 
 tain to follow, at the end of a longer or shorter time, if any one of 
 these substances be compelled to remain in the body, and accumu- 
 late in the animal tissues and fluids. 
 
 The principal excrementitious substances known to exist in the 
 human body are as follows ; 
 
 1. Carbonic acid 
 
 2. Cholesterine 
 
 3. Urea . 
 
 4. Creatine 
 
 5. Creatinine . 
 
 6. Urate of soda 
 
 7. Urate of potass 
 
 8. Urate of ammon 
 
 CO, 
 
 C2 H2,0 
 
 C^H.N^O^ 
 
 C.HgNaO, 
 
 CgH.NjO.^ 
 
 NaO.C.HN^Oj+HO 
 
 KO.CjHN.O^ 
 
 NH,0,2C5HN202-fHO 
 
 Of these substances the first two have already been studied at 
 sufficient length in the preceding chapters. We will merely repeat 
 here that carbonic acid is produced in large quantity in nearly all 
 the tissues of the body, from which it is absorbed by the blood, 
 conveyed to the lungs, and there exhaled at the sarrie time that 
 oxygen is absorbed. Cholesterine is a non-saponifiable fatty sub- 
 stance, originating in the brain and spinal cord, in the tissue of 
 which organs it exists in the proportion of 58 parts per thousand. 
 It is thence taken up by the blood, conveyed to the liver and dis- 
 charged with the bile. Cholesterine is extremely insoluble in 
 water, but is held in solution in the blood and the bile, by some of 
 the other ingredients present in these animal fluids. 
 
 The remaining excrementitious substances ma}^ be examined 
 together, with the more propriety, since they are all ingredients of 
 a single excretory fluid, viz., the urine. 
 
 UREA. 
 
 This is a neutral, crystallizable, nitrogenous substance, very 
 readily soluble in water, and easily decomposed by various external 
 influences. It occurs in the urine in the proportion of 30 parts 
 per thousand; and in the blood in much smaller quantity. The 
 blood, however, is the source from which this substance is sup- 
 plied to the urine ; and it exists, accordingly, in but small quantity 
 in the circulating fluid, for the reason that it is constantly drained 
 off by the kidneys. But if the kidneys be extirpated, or the renal 
 arteries tied, or the excretion of urine suspended by inflammation 
 
UEEA. 
 
 285 
 
 or otherwise, the urea then accumulates in the blood, and presents 
 itself there in considerable quantity. It has been found in the 
 blood, under these circum- 
 stances, in the proportion of Fig- m. 
 1.4 per thousand.' It is not 
 yet known from what source 
 the urea is originally derived ; 
 whether it be produced in the 
 blood itself, or whether it be 
 formed in some of the solid 
 tissues, and thence taken up by 
 the blood. It has not yet been 
 found, however, in any of the 
 solid tissues, in a state of health. 
 
 Urea is obtained most readily 
 from the urine. For this pur- 
 pose the fresh urine is evapo- 
 rated, in the water bath until it 
 
 has a syrupy consistency. It is then mixed with an equal volume of 
 nitric acid, which forms nitrate of urea. This salt, being less soluble 
 than pure urea, rapidly crystallizes, after which it is separated by 
 filtration from the other ingredients. It is then dissolved in water 
 and decomposed by carbonate of lead, forming nitrate of lead which 
 remains in solution, and carbonic acid which escapes. The solution 
 is then evaporated, the urea dissolved out by alcohol, and finally 
 crystallized in a pure state. 
 
 Urea has no tendency to spontaneous decomposition, and may 
 be kept, when perfectly pure, in a dry state or dissolved in water, 
 for an indefinite length of time. If the watery solution be boiled, 
 however, the urea is converted, during the process of ebullition, 
 into carbonate of ammonia. One equivalent of urea unites with 
 two equivalents of water, and becomes transformed into two equiva- 
 lents of carbonate of ammonia, as follows : — 
 
 Urea, prepared from urine, and crystallized by 
 slow evaporation. (After Lehmann.) 
 
 C,H^N202=Urea. 
 H, 0,=Water. 
 
 NH3,C02=Carbonate of ammonia. 
 
 2 
 
 Various impurities, also, by acting as catalytic bodies, will in- 
 duce the same change, if water be present. Animal substances in 
 a state of commencing decomposition are particularly liable to act 
 
 Robin and Verdeil, vol. ii. p. 502. 
 
286 EXCRETION. 
 
 in this way. In order that the conversion of the urea be thus 
 produced, it is necessary that the temperature of the mixture be 
 not far from 70° to 100° F. 
 
 The quantity of urea produced and discharged daily by a healthy 
 adult is, according to the experiments of Lehmann, about 500 
 grains. It varies to some extent, like all the other secreted and 
 excreted products, with the size and development of the body. 
 Lehmann, in experiments on his own person, found the average 
 daily quantity to be 487 grains. Dr. William A. Hammond,' of 
 the U. S. Array, who is a very large man, by similar experiments 
 found it to be 670 grains. Dr. John C. Draper'^ found it 408 
 grains. No urea is to be detected in the urine of very young 
 children ;^ but it soon makes its appearance, and afterward increases 
 in quantity with the development of body. 
 
 The daily quantity of urea varies also with the degree of mental 
 and bodily activity. Lehmann and Hammond both found it very 
 sensibly increased by muscular exertion and diminished by repose. 
 It has been thought, from these facts, that this substance must be 
 directly produced from disintegration of the muscular tissue. This, 
 however, is by no means certain ; since in a state of general bodily 
 activity it is not only the urea, but the excretions generally, carbonic 
 acid, perspiration, &c., which are increased in quantity simultane- 
 ously with each other. Hammond has also shown that continued 
 mental application will raise the quantity of urea above its normal 
 standard, though the muscular system remain comparatively in- 
 active. 
 
 The quantity of urea varies also with the nature of the food. 
 Lehmann, by experiments on his own person, found that the quan- 
 tity was larger while living exclusively on animal food than with 
 a mixed, or vegetable diet ; and that its quantity was smallest when 
 confined to a diet of purely non-nitrogenous substances, as starch, 
 sugar, and oil. The following table* gives the result of these ex- 
 periments. 
 
 Kind of Food. Daily Quantity of Urea. 
 
 Animal 798 grains. 
 
 Mixed 487 " 
 
 Vegetable 337 " 
 
 Non-nitrogenous ...... 231 " 
 
 ' American Journal Med. Sci., Jan., 1855, and April, 1856. 
 
 ^ New York Journal of Medicine, March, 1856. 
 
 ^ Robin and Veideil, vol. ii. p. 500. 
 
 '' Lehmann, op. cit., vol. ii. p. 163. 
 
CREATINE, 
 
 287 
 
 Finally, it has been shown by Dr. John C. Draper' that there is 
 also a diurnal variation in the normal quantity of urea. A smaller 
 quantity is produced during the night than during the day ; and 
 this difference exists even in patients who are confined to the bed 
 during the whole twenty-four hours, as in the case of a man under 
 treatment for fracture of the leg. This is probably owing to the 
 greater activity, during the waking hours, of both the mental and 
 digestive functions. More urea is produced in the latter half than 
 in the earlier half of the day; and the greatest quantity is dis- 
 charged during the four hours from 6| to lOJ P. M. 
 
 Urea exists in the urine of the carnivorous and many of the 
 herbivorous quadrupeds ; but there is little or none to be found in 
 that of birds and reptiles. 
 
 CREATINE. 
 
 This is a neutral crystallizable substance, found in the muscles, 
 the blood, and the urine. It is soluble in water, very slightly solu- 
 ble in alcohol, and not at all 
 
 so in ether. By boiling with ^'S* ^^?: 
 
 an alkali, it is either converted 
 into carbonic acid and ammonia, 
 or is decomposed with the pro- 
 duction of urea and an artificial 
 nitrogenous crystallizable sub- 
 stance, termed sarcosine. By 
 being heated with strong acids, 
 it loses two equivalents of water, 
 and is converted into the sub- 
 stance next to be described, viz., 
 creatinine. 
 
 Creatine exists in the urine, 
 in the human subject, in the 
 proportion of about 1.25 parts, 
 
 and in the muscles in the proportion of 0.67 parts per thousand. 
 Its quantity in the blood has not been determined. In the muscu- 
 lar tissue it is simply in solution in the interstitial fluid of the parts, 
 so that it may be extracted by simply cutting the muscle into 
 
 Creatine, crystallized from hot water. (After 
 Lehmauu ) 
 
 ' Loc. cit. 
 
288 
 
 EXCRETION. 
 
 small pieces, treating it with distilled water, and subjecting it to 
 pressure. Creatine evidently originates in the muscular tissue, is 
 absorbed thence bj the blood, and is finally discharged with the 
 
 urine. 
 
 CREATININE. 
 
 This is also a crystallizable substance. It differs in composition 
 from creatine by containing two equivalents less of the elements 
 of water. It is more soluble in water and in spirit than creatine, 
 and dissolves slightly also in ether. It has a distinctly alkaline 
 reaction. It occurs, like crea- 
 tine, in the muscles, the blood, §' 
 and the urine ; and is undoubt- 
 edly first produced in the 
 muscular tissue, to be dis- 
 charged finally by the kidneys. 
 It is very possible that it ori- 
 ginates, not directly from the 
 muscles, but indirectly, by trans- 
 formation of a part of the crea- 
 tine; since it may be artificially 
 produced, as we have already 
 mentioned, by transformation 
 of the latter substance under 
 the influence of strong acids, 
 and since, furthermore, while 
 creatine is more abundant in the muscles than creatinine, in the 
 urine, on the contrary, there is a larger quantity of creatinine than 
 of creatine. Both these substances have been found in the muscles 
 and in the urine of the lower animals. 
 
 C RE AT IX IN E, crystallized from hot water. 
 (Afier Lehmann.) 
 
 URATE OF SODA. 
 
 As its name implies, this substance is a neutral salt, formed by 
 the union of soda, as a base, with a nitrogenous animal acid, viz., 
 uric acid {G^^Jd^^O). Uric acid is sometimes spoken of as though 
 it were itself a proximate principle, and a constituent of the urine; 
 but it cannot properly be regarded as such, since it never occurs in 
 
URATES OF POTASS AND AMMONIA. 
 
 289 
 
 a free state, in a natural condition of the fluids. When present, it 
 has always been produced by decomposition of the urate of soda. 
 
 Urate of soda is readily soluble in hot water, from which a large 
 portion again deposits on cooling. It is slightly soluble in alcohol, 
 and insoluble in ether. It 
 crystallizes in small globular '^" 
 
 masses, with projecting, curv- 
 ed, conical, wart-like excres- 
 cences. (Fig. 114.) It dis- 
 solves readily in the alkalies; 
 and by most acid solutions it 
 is decomposed, with the pro- 
 duction of free nric acid. 
 
 Urate of soda exists in the 
 urine and in the blood. It is 
 either produced originally in 
 the blood, or is formed in 
 some of the solid tissues, and 
 absorbed from them by the 
 circulating fluid. It is con- 
 stantly eliminated by the kidneys, in company with the other ingre- 
 dients of the urine. The average daily quantity of urate of soda 
 discharged by the healthy human subject is, according to Lehmann, 
 about 25 grains. This substance exists in the urine of the carnivo- 
 rous and omnivorous animals, but not in that of the herbivora. 
 In the latter, it is replaced by another substance, differing some- 
 what from it in composition and properties, viz., hippurate of soda. 
 The urine of herbivora, however, while still very young, and living 
 upon the milk of the, mother, has been found to contain urates. 
 But when the young animal is weaned, and becomes herbivorous, 
 the urate of soda disappears, and is replaced by the hippurate. 
 
 TJeate of Soda: from a urinary deposit. 
 
 URATES OF POTASS AND AMMONIA. 
 
 The urates of potass and ammonia resemble the preceding salt 
 very closely in their physiological relations. They are formed in 
 very much smaller quantity than the urate of soda, and appear like 
 it as ingredients of the urine. 
 
 The substances above enumerated resemble each other closely in 
 19 
 
290 EXCRETION. 
 
 their most striking and important characters. They all contain 
 nitrogen, are all crystallizable, and all readily soluble in water. 
 They all originate in the interior of the body by the decomposition 
 or catalytic transformation of its organic ingredients, and are all 
 conveyed by the blood to the kidneys, to be finally expelled with 
 the urine. These are the substances which represent, to a great 
 extent, the final transformation of the organic or albuminoid in- 
 gredients of the tissues. It has already been mentioned, in a pre- 
 vious chapter, that these organic or albuminoid substances are not 
 discharged from the body, under their own form, in quantity at all 
 proportionate to the abundance with which they are introduced. 
 By far the greater part of the mass of the frame is made up of 
 organic substances: albumen, musculine, osteine, &c. Similar 
 materials are taken daily in large quantity with the food, in order 
 to supply the nutrition and waste of those already composing the 
 tissues; and yet only a very insignificant quantity of similar 
 material is expelled with the excretions. A minute proportion of 
 volatile animal matter is exhaled with the breath, and a minute 
 proportion also with the perspiration. A very small quantity is 
 discharged under the form of mucus and coloring matter, with the 
 urine and feces ; but all these taken together are entirely insuffi- 
 cient to account for the constant and rapid disappearance of organic 
 matters in the interior of the body. These matters, in fact, before 
 being discharged, are converted by catalysis and decomposition into 
 new substances. Carbonic acid, under which form 3500 grains of 
 carbon are daily expelled from the body, is one of these substances ; 
 the others are urea, creatine, creatinine, and the urates. 
 
 We see, then, in what way the organic matters, in ceasing to 
 form a part of the living body, lose their characteristic properties, 
 and are converted into crystallizable substances, of definite chemical 
 composition. It is a kind of retrograde metamorphosis, by which 
 they return more or less to the condition of ordinary inorganic 
 materials. These excrementitious matters are themselves decom- 
 posed, after being expelled from the body, under the influence of 
 the atmospheric air and moisture ; so that the decomposition and 
 destruction of the organic substances is at last complete. 
 
 It will be seen, consequently, that the urine has a character 
 altogether peculiar, and one which distinguishes it completely 
 from every other animal fluid. All the others are either nutritive 
 fluids, like the blood and milk, or are destined, like the secretions 
 
GENERAL CHARACTERS OF THE URINE. 291 
 
 generally, to take some direct and essential part in the vital opera- 
 tions. Many of them, like the gastric and pancreatic juices, are 
 reabsorbed after they have done their work, and again enter the 
 current of the circulation. But the urine is merely a solution of 
 excrementitious substances. Its materials exist beforehand in the 
 circulation, and are simply drained away by the kidneys from 
 the blood. There is a wide difference, accordingly, between the 
 action of the kidneys and that of the true glandular organs, in 
 which certain new and peculiar substances are produced by the 
 action of the glandular tissue. The kidneys, on the contrary, do 
 not secrete anything, properly speaking, and are not, therefore, 
 glands. In their mode of action, so far as regards the excretory 
 function, they have more resemblance to the lungs than to any 
 other of the internal organs. But this resemblance is not complete ; 
 since the lungs perform a double function, absorbing oxygen at the 
 same time that they exhale carbonic acid. The kidneys alone are 
 purely excretory in their office. The urine is not intended to 
 fulfil any function, mechanical, chemical, or otherwise ; but is des- 
 tined only to be eliminated and expelled. Since it possesses so 
 peculiar and important a character, it will require to be carefully 
 studied in detail. 
 
 The urine is a clear, watery, amber-colored fluid, with a distinct 
 acid reaction. It has, while still warm, a peculiar odor, which dis- 
 appears more or less completely on cooling, and returns when the 
 urine is gently heated. The ordinary quantity of urine discharged 
 daily by a healthy adult is about ^xxxv, and its mean specific 
 gravity, 1024. Both its total quantity, however, and its mean 
 specific gravity are liable to vary somewhat from day to day, owing 
 to the different proportion of water and solid ingredients entering 
 into its constitution. Ordinarily the water of the urine is more 
 than sufficient to hold all its solid matters in solution ; and its pro- 
 portion may therefore be diminished by accidental causes without 
 the urine becoming turbid by the formation of a deposit. Under 
 such circumstances, it merely becomes deeper in color, and of a 
 higher specific gravity. Thus, if a smaller quantity of water than 
 usual be taken into the system with the drink, or if the fluid ex- 
 halations from the lungs and skin, or the intestinal discharges, be 
 increased, a smaller quantity of water will necessarily pass off by 
 the kidneys; and the urine will be diminished in quantity, while its 
 specific gravity is increased. We have observed the urine to be 
 
292 EXCEETION. 
 
 reduced in this way to eighteen or twenty ounces per day, its specific 
 gravity rising at the same time to 1030. On the other hand, if the 
 fluid ingesta be unusually abundant, or if the perspiration be dimi- 
 nished, the surplus quantity of water will pass oif by the kidneys; so 
 that the amount of urine in twenty-four hours may be increased to 
 forty-five or forty-six ounces, and its specific gravity reduced at 
 the same time to 1020 or even 1017. Under these conditions the 
 total amount of solid matter discharged daily remains about the 
 same. The changes above mentioned depend simply upon the 
 fluctuating quantity of water, which may pass off by the kidneys 
 in larger or smaller quantity, according to accidental circumstances. 
 In these purely normal or physiological variations, therefore, the 
 entire quantity of the urine and its mean specific gravity vary 
 always in an inverse direction with each other ; the former increas- 
 ing while the latter diminishes, and vice versa. If, however, it 
 should be found that both the quantity and specific gravity of the 
 urine were increased or diminished at the same time, or if either 
 one were increased or diminished while the other remained station- 
 ary, such an alteration would show an actual change in the total 
 amount of solid ingredients, and would indicate an unnatural and 
 pathological condition. This actually takes place in many forms 
 of disease. 
 
 The amount of variation in the quantity of water, even, may be 
 so great as to constitute by itself a pathological condition. Thus, 
 in hysterical attacks there is sometimes a very abundant flow of 
 limpid, nearly colorless urine, with a specific gravity not over 1005 
 or 1006. On the other hand, in the onset of febrile attacks, the 
 quantity of water is often so much diminished that it is no longer 
 sufficient to retain in solution all the solid ingredients of the urine, 
 and the urate of soda is thrown down, after cooling, as a fine red 
 or yellowish sediment. So long, however, as the variation is con- 
 fined within strictly physiological limits, all the solid ingredients 
 are held in solution, and the urine remains clear. 
 
 There is also, in a state of health, a diurnal variation of the urine, 
 both in regard to its specific gravity and its degree of acidity. 
 The urine is generally discharged from the bladder five or six 
 times during the twenty-four hours, and at each of these periods 
 shows more or less variation in its physical characters. We have 
 found that the urine which collects in the bladder during the night, 
 and is discharged the first thing in the morning, is usually dense, 
 
DIURNAL YARIATI0X3 OF THE URINE. 293 
 
 highly colored, of a strongly acid reaction, and a high specific 
 gravity. That passed during the forenoon is pale, and of a low 
 specific gravit}'', sometimes not more than 1018 or even 1015. It 
 is at the same time neutral or slightly alkaline in reaction. Toward 
 the middle of the day, its density and depth of color increase, and 
 its acidity returns. All these properties become more strongl}- 
 marked during the afternoon and evening, and toward night the 
 urine is again deeply colored and strongly acid, and has a specific 
 gravity of 1028 or 1030. 
 
 The following instances will serve to show the general characters 
 of this variation : — 
 
 Observation First. March 20 fh. 
 Urine of 1st discharge, acid, sp. gr. 1025. 
 " 2d " alkaline, " 1015. 
 
 •' 3d " neutral, " 1018. 
 
 " 4th " acid, " 1018. 
 
 " 5th " acid, " 1027. 
 
 Observation Second. March 21st. 
 Urine of 1st discharge, acid, sp. gr. 1029. 
 " 2d " neutral, " 1022. 
 
 " 3d " neutral, " 1025. 
 
 " 4th " acid, " 1027. 
 
 « 5th " acid, " 1030. 
 
 These variations do not always follow the perfectly regular 
 course manifested in the above instances, since they are somewhat 
 liable, as we have already mentioned, to temporary modification 
 from accidental causes during the day ; but their general tendency 
 nearly always corresponds with that given above. 
 
 It is evident, therefore, that whenever we wish to test the specific 
 gravity and acidity of the urine in cases of disease, it will not be 
 sufficient to examine any single specimen taken at random ; but all 
 the different portions discharged during the day should be collected 
 and examined together. Otherwise, we should incur the risk of 
 regarding as a permanently morbid symptom what might be 
 nothing more than a purely accidental and temporary variation. 
 
 The chemical constitution of the urine as it is discharged from the 
 bladder, according to the analyses of Berzelius, Lehmann, Becquerel, 
 and others, is as follows : — 
 
294 EXCKETION. 
 
 Composition of the Urine. 
 
 Water 938.00 
 
 Urea 30.00 
 
 Creatine ........... 1.25 
 
 Creatinine .......... 1.50 
 
 Urate of soda -^ 
 
 " potass I 1.80 
 
 " ammonia J 
 Coloring matter and •> o^ 
 
 Mucus J 
 
 Biphosphate of soda -\ 
 Phosphate of soda j 
 
 " potass I- 12.45 
 
 " magnesia I 
 
 " lime J 
 
 Chlorides of sodium and potassium 7.80 
 
 Sulphates of soda and potass ....... 6.90 
 
 1000.00 
 
 We need not repeat that the proportionate quantity of these 
 different ingredients, as given above, is not absolute, but only 
 approximative ; and that they vary, from time to time, within cer- 
 tain physiological limits, like the ingredients of all other animal 
 fluids. 
 
 The urea, creatine, creatinine, and urates have all been suffi- 
 ciently described above. The mucus and coloring matter, unlike 
 the other ingredients of the urine, belong to the class of organic 
 substances proper. They are both present, as may be seen by the 
 analysis quoted above, in very small quantity. The coloring 
 matter, or urosacine, is in solution in a natural condition of the 
 urine, but is apt to be entangled by any accidental deposits which 
 may be thrown down, and more particularly by those consisting of 
 the urates. These deposits, from being often strongly colored red 
 or pink by the urosacine thus thrown down with them, are known 
 under the name of " brick-dust" sediments. 
 
 The mvcus of the urine comes from the lining membrane of the 
 urinary bladder. When first discharged it is not visible, owing to 
 its being uniformly disseminated through the urine by mechanical 
 agitation ; but if the fluid be allowed to remain at rest for some 
 hours in a cylindrical glass vessel, the mucus collects at the bottom, 
 and may then be seen as a light cottony cloud, interspersed often 
 with minute semi-opaque points. It plays, as we shall hereafter 
 see a very important part in the subsequent fermentation and 
 decomposition of the urine. 
 
EEACTIONS OF THE URINE. 295 
 
 Biphosphate of soda exists in the urine by direct solution, since it is 
 readily soluble in water. It is this salt which gives to the urine its 
 acid reaction, as there is no free acid present in the recent condition. 
 It is probably derived from the neutral phosphate of soda in the 
 blood, which is decomposed by the uric acid at the time of its for- 
 mation ; producing, on the one hand, a urate of soda, and converting 
 a part of the neutral phosphate of soda into the acid biphosphate. 
 
 The phosphates of lime and magnesia, or the " earthy phosphates," 
 as they are called, exist in the urine by indirect solution. Though 
 insoluble, or very nearly so, in pure water, they are held in solu- 
 tion in the urine by the acid phosphate of soda, above described. 
 They are derived from the blood, in which they exist in considera- 
 ble quantity. When the urine is alkaline, these phosphates are 
 deposited as a light colored precipitate, and thus communicate a 
 turbid appearance to the fluid. When the urine is neutral, they 
 may still be held in solution, to some extent, by the chloride of 
 sodium, which has the property of dissolving a small quantity of 
 phosphate of lime. 
 
 The remaining ingredients, phosphates of soda and potass, sul- 
 phates and chlorides, are all derived from the blood, and are held 
 directly in solution by the water of the urine. 
 
 The urine, constituted by the above ingredients, forms, as we 
 have already described, a clear amber colored fluid, with a reaction 
 for the most part distinctly acid, sometimes neutral, and occasion- 
 ally slightly alkaline. In its healthy condition it is affected by 
 chemical and physical reagents in the following manner. 
 
 Boiling the urine does not produce any visible change, provided 
 its reaction be acid. If it be neutral or alkaline, and if, at the same 
 time, it contain a larger quantity than usual of the earthy phos- 
 phates, it will become turbid on boiling ; since these salts are less 
 soluble at a high than at a low temperature. 
 
 The addition of nitric, or other mineral acid, produces at first only 
 a slight darkening of the color, owing to the action of the acid upon 
 the organic coloring matter of the urine. If the mixture, however, 
 be allowed to stand for some time, the urates of soda, potass, &c., 
 will be decomposed, and pure uric acid, which is very insoluble, 
 will be deposited in a crystalline form upon the sides and bottom 
 of the glass vessel. The crystals of uric acid have most frequently 
 the form of transparent rhomboidal plates, or oval laminae with 
 pointed extremities. They are usually tinged of a yellowish hue 
 by the coloring matter of the urine which is entangled with them 
 
296 
 
 EXCEETION. 
 
 Uric Acid; deposited from urine. 
 
 at the time of their deposit. They are frequently arranged in 
 radiated clusters, or small spheroidal masses, so as to present the 
 
 appearance of minute calcu- 
 Fig- 115- lous concretions. (Fig. 115.) 
 
 The crystals vary very much 
 in size and regularity, ac- 
 cording to the time occupied 
 in their formation. 
 
 If a free alkali, such as 
 potass or soda, be added to 
 the urine, so as to neutralize 
 its acid reaction, it becomes 
 immediately turbid from a 
 deposit of the earthy phos- 
 phates, which are insoluble 
 in alkaline fluids. 
 
 The addition of nitrate of 
 baryta, chloride of barium, 
 or subacetate of lead to healthy urine, produces a dense precipi- 
 tate, owing to the presence of the alkaline sulphates. 
 
 Nitrate of silver produces a precipitate with the chlorides of 
 sodium and potassium. 
 
 Subacetate of lead and nitrate of silver precipitate also the or- 
 ganic substances, mucus and coloring matter, present in the urine. 
 All the above reactions, it will be seen, are owing to the presence 
 of the natural ingredients of the urine, and do not, therefore, indi- 
 cate any abnormal condition of the excretion. 
 
 Besides the properties mentioned above, the urine has several 
 others which are of some importance, and which have not been 
 usually noticed in previous descriptions. It contains, among other 
 ingredients, certain organic substances which have the power of in- 
 terfering with the mutual reaction of starch and iodine, and even of 
 decomposing the iodide of starch, after it has once been formed. 
 This peculiar action of the urine was first noticed and described 
 by us in 1856.^ If 5j of iodine water be mixed with a solution 
 of starch, it strikes an opaque blue color ; but if 5j of fresh urine 
 be afterward added to the mixture, the color is entirely destroyed 
 at the end of four or five seconds. If fresh urine again be mixed 
 with four or five times its volume of iodine water, and starch be 
 
 ' American Journal Med. Sci., April, 1856. 
 
ACCIDENTAL INGEEDIENTS OF THE UKINE. 297 
 
 subsequently added, no union takes place between the starch and 
 iodine, and no blue color is produced. In these instances, the iodine 
 unites with the animal matters of the urine in preference to com- 
 bining with the starch, and is consequently prevented from striking 
 its ordinary blue color with the latter. This interference occurs 
 whether the urine be acid or alkaline in reaction. In all cases in 
 which iodine exists in the urine, as for example where it has been 
 administered as a medicine, it is under the form of an organic com- 
 bination ; and in order to detect its presence by means of starch, a 
 few drops of nitric acid must be added at the same time, so as to 
 destroy the organic matters, after which the blue color immediately 
 appears, if iodine be present. This reaction with starch and iodine 
 belongs also, to some extent, to most of the other animal fluids, as 
 the saliva, gastric and pancreatic juices, serum of the blood, &c. ; 
 but it is most strongly marked in the urine. 
 
 Another remarkable property of the urine, also dependent on its 
 organic ingredients, is that of interfering with Trommer's test for 
 grape sugar. If clarified honey be mixed with fresh urine, and sul- 
 phate of copper with an excess of potass be afterward added, the 
 mixture takes a dingy, grayish-blue color. On boiling, the color 
 turns yellowisb or yellowish-brown, but the suboxide of copper is 
 not deposited. In order to remove the organic matter and detect 
 the sugar, the urine must be first treated with an excess of animal 
 charcoal and filtered. By this means the organic substances are 
 retained upon the filter, while the sugar passes through in solution, 
 and may then be detected as usual by Trommer's test. 
 
 Accidental Ingeedients of the Ueine. — Since the urine, in 
 its natural state, consists of materials which are already prepared in 
 the blood, and which merely pass out through the kidneys by a 
 kind of filtration, it is not surprising that most medicinal and 
 poisonous substances, introduced into the circulation, should be 
 expelled from the body by the same channel. Those substances 
 which tend to unite strongly with the animal matters, and to form 
 with them insoluble compounds, such as the preparations of iron, 
 lead, silver, arsenic, mercury, &c., are least liable to appear in the 
 urine. They may occasionally be detected in this fluid when they 
 have been given in large doses, but when administered in moderate 
 quantity are not usually to be found there. Most other substances, 
 however, accidentally present in the circulation, pass off readily by 
 
298 EXCRETION. 
 
 the kidneys, either in their original form, or after undergoing cer- 
 tain chemical modifications. 
 
 The salts of the organic acids, such as lactates^ acetates, malates, 
 &G., of soda and potass, when introduced into the circulation, are 
 replaced by the carbonates of the same bases, and appear under 
 that form in the urine. The urine accordingly becomes alkaline 
 from the presence of the carbonates, whenever the above salts have 
 been taken in large quantity, or after the ingestion of fruits and 
 vegetables which contain them. We have already spoken (Chap. II.) 
 of the experiments of Lehmann, in which he found the urine exhi- 
 biting an alkaline reaction, a very few minutes after the adminis- 
 tration of lactates and acetates. In one instance, by experimenting 
 upon a person with congenital extroversion of the bladder, in whom 
 the orifices of the ureters were exposed,^ he found that the urine 
 became alkaline in the course of seven minutes after the ingestion 
 of half an ounce of acetate of potass. 
 
 The 2^ure alkalies and their carbonates, according to the same ob- 
 server, produce a similar effect. Bicarbonate of potass, for example, 
 administered in doses of two or three drachms, causes the urine 
 to become neutral in from thirty to forty-five minutes, and alkaline 
 in the course of an hour. It is in this way that certain "anti-cal- 
 culous" or " anti-lithic" nostrums operate, when given with a view 
 of dissolving concretions in the bladder. These remedies, which 
 are usually strongly alkaline, pass into the urine, and by giving it 
 an alkaline reaction, produce a precipitation of the earthy phos- 
 phates. Such a precipitate, however, so far from indicating the 
 successful disintegration and discharge of the calculus, can only 
 tend to increase its size by additional deposits. 
 
 Ferrocyanide of potassium, when introduced into the circulation, 
 appears readily in the urine. Bernard^ observed that a solution of 
 this salt, after being injected into the duct of the submaxillary 
 gland, could be detected in the urine at the end of twenty minutes. 
 
 Iodine^ in all its combinations, passes out by the same channel. 
 We have found that after the administration of half a drachm of 
 the syrup of iodide of iron, iodine appears in the urine at the end 
 of thirty minutes, and continues to be present for nearly twenty- 
 four hours. In the case of two patients who had been taking iodide 
 of potassium freel}--, one of them for two months, the other for six 
 
 ' Physiological Chemistry, vol. ii. p. 133. 
 
 2 Leqons de Physiologie Experimentale, 1855, vol. ii. p. 111. 
 
ACCIDENTAL INGREDIENTS OF THE URINE. 299 
 
 weeks, the urine still contained iodine at the end of three days 
 after the suspension of the medicine. In three days and a half, 
 however, it was no longer to be detected. Iodine appears also, after 
 being introduced into the circulation, both in the saliva and the 
 perspiration. 
 
 Quinine^ when taken as a remedy, has also been detected in the 
 urine. Ether passes out of the circulation in the same way. We 
 have observed the odor of this substance very perceptible in the 
 urine, after it had been inhaled for the purpose of producing anees- 
 thesia. The bile-pigment passes into the urine in great abundance 
 in some cases of jaundice, so that the urine may have a deep yellow 
 or yellowish brown tinge, and may even stain linen clothes, with 
 which it comes in contact, of a similar color. The saline biliary 
 substances, viz., glyko-cholate and tauro-cholate of soda, have occa- 
 sionally, according to Lehmann, been also found in the urine. In 
 these instances the biliary matters are reabsorbed from the hepatic 
 ducts, and afterward conveyed by the blood to the kidneys. 
 
 Sugar. — When sugar exists in unnatural quantity in the blood, it 
 passes out with the urine. We have repeatedly found that if sugar 
 be artificially introduced into the circulation in rabbits, or injected 
 into the subcutaneous areolar tissue so as to be absorbed by the 
 blood, it is soon discharged by the kidneys. It has been shown by 
 Bernard* that the rapidity with which this substance appears in the 
 urine under these circumstances varies with the quantity injected 
 and the kind of sugar used for the experiment. If a solution of 15 
 grains of glucose be injected into the areolar tissue of a rabbit 
 weighing a little over two pounds, it is entirely destroyed in the cir- 
 culation, and does not pass out with the urine. A dose of 23 grains, 
 however, injected in the same way, appears in the urine at the end 
 of two hours, 30 grains in an hour and a half, 38 grains in an hour, 
 and 188 grains in fifteen minutes. Again, the kind of sugar used 
 causes a difference in this respect. For while 15 grains of glucose 
 may be injected without passing out by the kidneys, 7J grains of 
 cane sugar, introduced in the same way, fail to be completely de- 
 stroyed in the circulation, and may be detected in the urine. In 
 certain forms of disease (diabetes), where sugar accumulates in 
 the blood, it is eliminated by the same channel ; and a saccharine 
 condition of the urine, accompanied by an increase in its quantity 
 
 ' Legons de Phys. Exp., 1855, vol. i. p. 214 et seq. 
 
300 EXCEETION. 
 
 and specific gravity, constitutes the most cbaracteristic feature of 
 the disease. 
 
 Finally, albumen sometimes shows itself in the urine in conse- 
 quence of various morbid conditions. Most acute inflammations 
 of the internal organs, as pneumonia, pleurisy, &c., are liable to be 
 accompanied, at their outset, by a congestion of the kidneys, which 
 produces a temporary exudation of the albuminous elements of the 
 blood. Albumen has been found in the urine, according to Simon, 
 Becquerel, and others, in pericarditis, pneumonia, pleurisy, bron- 
 chitis, hepatitis, inflammation of the brain, peritonitis, metritis, &c. 
 "We have observed it, as a temporary condition, in pneumonia and 
 after amputation of the thigh. Albuminous urine also occurs fre- 
 quently in pregnant women, and in those affected with abdominal 
 tumors, where the pressure upon the renal veins is sufficient to 
 produce passive congestion of the kidneys. When the renal con- 
 gestion is spontaneous in its origin, and goes on to produce actual 
 degeneration of the tissue of the kidneys, as in Bright's disease, 
 the same symptom occurs, and remains as a permanent condition. 
 In all such instances, however, as the above, where foreign ingre- 
 dients exist in the urine, these substances do not originate in the 
 kidneys themselves, but are derived from the blood, in the same 
 manner as the natural ingredients of the excretion. 
 
 Changes in the Urine during Decomposition, — When the 
 urine is allowed to remain exposed, after its discharge, at ordinary 
 temperatures, it becomes decomposed, after a time, like any other 
 animal fluid ; and this decomposition is characterized by certain 
 changes which take place in a regular order of succession, as fol- 
 lows: — 
 
 After a few hours of repose, the mucus of the urine, as we have 
 mentioned above, collects near the bottom of the vessel as a light, 
 nearly transparent, cloudy layer. This mucus, being an organic sub- 
 stance, is liable to putrefaction ; and if the temperature to which it is 
 exposed be between 60° and 100° F., it soon becomes altered and 
 communicates these alterations, more or less rapidly, to the superna- 
 tant fluid. The first of these changes is called the acid fermentation 
 of the urine. It consists in the production of a free acid, usually 
 lactic acid, from some of the undetermined animal matters con- 
 tained in the excretion. This fermentation takes place very early ; 
 within the first twelve, twenty-four, or forty-eight hours, according 
 to the elevation of the surrounding temperature. Perfectly fresh 
 
ACID FERMENTATION OF THE URINE. 301 
 
 urine, as we have already stated, contains no free acid, its acid 
 reaction to test paper being dependent entirely on the presence of 
 biphosphate of soda. Lactic acid nevertheless has been so fre- 
 quently found in nearly fresh urine as to lead some eminent 
 chemists (Berzelius, Lehmann) to regard it as a natural constituent 
 of the excretion. It has been subsequently found, however, that 
 urine, though entirely free from lactic when first passed, may fre- 
 quently present traces of this substance after some hours' exposure 
 to the air. The lactic acid is undoubtedly formed, in these cases, 
 by the decomposition of some animal substance contained in the 
 urine. Its production in this way, though not constant, seems to 
 be sufficiently frequent to be regarded as a normal process. 
 
 In consequence of the presence of this acid, the urates are par- 
 tially decomposed ; and a crystalline deposit of free uric acid slowly 
 takes place, in the same manner as if a little nitric or muriatic acid 
 had been artificially mixed with the urine. It is for this reason 
 that urine which is abundant in the urates frequently shows a de- 
 posit of crystallized uric acid some hours after it has been passed, 
 though it may have been perfectly free from deposit at the time 
 of its emission. 
 
 During the period of the "acid fermentation," there is reason to 
 believe that oxalic acid is also sometimes produced in a similar 
 manner with the lactic. It is very certain that the deposit of oxa- 
 late of lime, far from being a dangerous or even morbid symptom, 
 as it was at one time regarded, is frequently present in perfectly 
 normal urine after a day or two of exposure to the atmosphere. 
 We have often observed it, under these circumstances, when no 
 morbid symptom could be detected in connection with either the 
 kidneys or any other bodily organ. Now, whenever oxalic acid 
 is formed in the urine, it must necessarily be deposited under 
 the form of oxalate of lime ; since this salt is entirely insoluble 
 both in water and in the urine, even when heated to the boiling 
 point. It is difficult to understand, therefore, when oxalate of 
 lime is^ found as a deposit in the urine, how it can previously have 
 been held in solution. Its oxalic acid is in all probability gradually 
 formed, as we have said, in the urine itself; uniting, as fast as it is 
 produced, with the lime previously in solution, and thus appearing 
 as a crystalline deposit of oxalate of lime. It is much more probable 
 that this is the true explanation, since, in the cases to which we 
 allude, the crystals of oxalate of lime grow, as it were, in the cloud 
 of mucus which collects at the bottom of the vessel, while the 
 
302 
 
 EXCRETION. 
 
 Oxalate op Lime; deposited from healthy urine, 
 during the acid fevmentatiou. 
 
 supernatant fluid remains clear. These crystals are of minute size, 
 
 transparent, and colorless, 
 ^'S- ^^^- and have tlie form of regular 
 
 octohedra, or double quad- 
 rangular pyramids, united 
 base to base. (Fig. 116.) They 
 make their appearance usu- 
 ally about the commence- 
 ment of the second day, the 
 urine at the same time con- 
 tinuing clear and retaining 
 its acid reaction. This depo- 
 sit is of frequent occurrence 
 when no substance contain- 
 ing oxalic acid or oxalates 
 has been taken with the food. 
 At the end of some days 
 the changes above described 
 come to an end, and are succeeded by a different process known as 
 the alkaline fermentation. This consists essentially in the decompo- 
 sition or metamorphosis of the urea into carbonate of ammonia. 
 As the alteration of the mucus advances, it loses the power of pro- 
 ducing lactic and oxalic acids, and becomes a ferment capable of 
 acting by catalysis upon the urea, and of exciting its decomposition 
 as above. We have already mentioned that urea may be converted 
 into carbonate of ammonia by prolonged boiling or by contact 
 with decomposing animal substances. In this conversion, the urea 
 unites with the elements of two equivalents of water ; and conse- 
 quently it is not susceptible of the transformation when in a dry 
 state, but only when in solution or supplied with a sufficient quan- 
 tity of moisture. The presence of mucus, in a state of incipient 
 decomposition, is also necessary, to act the part of a catalytic body. 
 Consequently if the urine when first discharged be passed through 
 a succession of close filters, so as to separate and retain its mucus, it 
 may be afterward kept, for an almost indefinite time, without altera- 
 tion. But under ordinary circumstances, the mucus, as soon as its 
 putrefaction has commenced, excites the decomposition of the urea, 
 and carbonate of ammonia begins to be developed. 
 
 The first portions of the ammoniacal salt thus produced begin to 
 neutralize the biphosphate of soda, so that the acid reaction of the 
 urine diminishes in intensity. This reaction gradually becomes 
 
ALKALINE FERMENTATION OF THE URINE. 303 
 
 weaker and weaker, as the fermentation proceeds, until it at last 
 disappears altogether, and the urine becomes neutral. The produc- 
 tion of carbonate of ammonia still continuing, the reaction of the 
 fluid then becomes alkaline, and its alkalescence grows more strongly 
 pronounced with the constant accumulation of the ammoniacal salt. 
 
 The rapidity with which this alteration proceeds depends on the 
 character of the urine, the quantity and quality of the mucus which 
 it contains, and the elevation of the surrounding temperature. The 
 urine passed early in the forenoon, which is often neutral at the 
 time of its discharge, will of course become alkaline more readily 
 than that which has at first a strongly acid reaction. In the summer, 
 urine will become alkaline, if freely exposed, on the third, fourth, 
 or fifth day ; while in the winter, a specimen kept in a cool place 
 may still be neutral at the end of fifteen days. In cases of paralysis 
 of the bladder, on the other hand, accompanied with cystitis, where 
 the mucus is increased in quantity and altered in quality, and the 
 urine retained in the bladder for ten or twelve hours at the tem- 
 perature of the body, the change may go on much more rapidly, so 
 that the urine may be distinctly alkaline and ammoniacal at the 
 time of its discharge. In these cases, however, it is really acid 
 when first secreted by the kidneys, and becomes alkaline while 
 retained in the interior of the bladder. 
 
 The first effect of the alkaline condition of the urine, thus pro- 
 duced, is the precipitation of the earthy phosphates. These salts, 
 being insoluble in neutral and alkaline fluids, begin to precipitate as 
 soon as the natural acid reaction of the urine has fairly disappeared, 
 and thus produce in the fluid a whitish turbidity. This precipitate 
 slowly settles upon the sides and bottom of the vessel, or is partly 
 entangled with certain animal matters which rise to the surface and 
 form a thin, opaline scum upon the urine. There are no crystals 
 to be seen at this time, but the deposit is entirely amorphous and 
 granular in character. 
 
 The next change consists in the production of two new double 
 salts by the action of carbonate of ammonia on the phosphates of 
 soda and magnesia. One of these is the " triple phosphate," phos- 
 phate of magnesia and ammonia (2MgO,NHp,P05-f 2H0). The 
 other is the phosphate of soda and ammonia (NaO,NIip,IIO,POj-f 
 8H0). The phosphate of magnesia and ammonia is formed from 
 the phosphate of magnesia in the urine (SMgOjPO^+THO) by the 
 replacement of one equivalent of magnesia by one of ammonia. 
 The crystals of this salt are very elegant and characteristic. They 
 
304 
 
 EXCRETION. 
 
 Fig. 117. 
 
 Phosphate of Magnesia and Ammonia; 
 deposited from healthy urine, during alkaline fermen- 
 tation. 
 
 show themselves throughout all parts of the mixture ; growing gra- 
 dually in the mucus at the bottom, adhering to the sides of the 
 
 glass, and scattered abund- 
 antly over the film which col- 
 lects, as we have mentioned, 
 upon the surface. By their 
 refractive power, they give 
 to this film a peculiar glisten- 
 ing or iridescent appearance, 
 which is nearly always visi- 
 ble at the end of six or seven 
 days. The crystals are per- 
 fectly colorless and transpa- 
 rent, and have the form of 
 triangular prisms, generally 
 with bevelled extremities. 
 (Fig. 117.) Frequentlj'-, also, 
 their edges and angles are 
 replaced by secondary facets. 
 They are insoluble in alkalies, but are easily dissolved by acids, 
 even in a very dilute form. At first they are of minute size, but 
 gradually increase, so that after seven or eight days they may 
 become visible to the naked eye. 
 
 The phosphate of soda and ammonia is formed, in a similar man- 
 ner to the above, by the union of ammonia with the phosphate of 
 soda previously existing in the urine. Its crystals resemble very 
 much those just described, except that their prisms are of a quad- 
 rangular form, or some figure derived from it. They are inter- 
 mingled with the preceding in the putrefying urine, and are affected 
 in the same way by chemical reagents. 
 
 As the putrefaction of the urine continues, the carbonate of am- 
 monia which is produced, after saturating all the other ingredients 
 with which it is capable of entering into combination, begins to 
 be given off in a free form. The urine then acquires a strong 
 ammoniacal odor; and a piece of moistened test paper, held a little 
 above its surface, will have its color immediately turned by the 
 alkaline gas escaping from the fluid. This is the source of the 
 ammoniacal vapor which is so freely given off from stables and from 
 dung heaps, or wherever urine is allowed to remain and decompose. 
 This process continues until all the urea has been destroyed, and 
 until the products of its decomposition have either united with 
 other substances, or have finally escaped in a gaseous form. 
 
SECTION 11. 
 NERVOUS SYSTEM. 
 
 CHAPTER I. 
 
 GENERAL STRUCTURE AND FUNCTIONS OF THE 
 NERVOUS SYSTEM 
 
 Iisr entering upon the study of the nervous system, we commence, 
 the examination of an entirely different order of phenomena from 
 those which have thus far engaged our attention. Hitherto we 
 have studied the physical and chemical actions taking place in the 
 body and constituting together the process of nutrition. We have 
 seen how the lungs absorb and exhale different gases; how the 
 stomach dissolves the food introduced into it, and how the tissues 
 produce and destroy different substances by virtue of the varied 
 transformations which take place in their interior. In all these 
 instances, we have found each organ and each tissue possessing 
 certain properties and performing certain functions, of a physical 
 or chemical nature, which belong exclusively to it, and are charac- 
 teristic of its action. 
 
 The functions of the nervous system, however, are neither phy- 
 sical nor chemical in their nature. They do not correspond, in 
 their mode of operation, with any known phenomena belonging to 
 these two orders. The nervous system, on the contrary, acts only 
 upon other organs, in some unexplained manner, so as to excite or 
 modify the functions peculiar to them. It is not therefore an appa- 
 ratus which acts for itself, but is intended entirely for the purpose 
 of influencing, in an indirect manner, the action of other organs. 
 Its object is to connect and associate the functions of different parts 
 of the body, and to cause them to act in harmony with each other. 
 20 
 
306 GENERAL STRUCTURE AND FUNCTIONS 
 
 This object may be more fully exemplified as follows: — 
 Each organ and tissue in the body has certain properties peculiar 
 to it, which may be called into activity by the operation of a stimu- 
 lus or exciting cause. This capacity, which all the organs possess, 
 of reacting under the influence of a stimulus, is called their excita- 
 bility, or irntability. "We have often had occasion to notice this pro- 
 perty of irritability, in experiments related in the foregoing pages. 
 We have seen, for example, that if the heart of a frog, after being 
 removed from the body, be touched with the point of a needle, it 
 immediately contracts, and repeats the movement of an ordinary 
 pulsation. If the leg of a frog be separated from the thigh, its 
 integument removed, and the poles of a galvanic battery brought 
 in contact with the exposed surface of the muscles, a violent con- 
 traction takes place every time the electric circuit is completed. 
 In this instance, the stimulus to the muscles is supplied by the 
 electric discharge, as, in the case of the heart above mentioned, it is 
 supplied by the contact of the steel needle ; and in both, a muscu- 
 lar contraction is the immediate consequence. If we introduce a 
 metallic catheter into the empty stomach of a dog through a gastric 
 fistula, and gently irritate with it the mucous membrane, a secretion 
 of gastric juice at once begins to take place ; and if food be intro- 
 duced the fluid is poured out in still greater abundance. We know 
 also that if the integument be exposed to contact with a heated 
 body, or to friction with an irritating liquid, an excitement of the 
 circulation is at once produced, which again passes away after the 
 removal of the irritating cause. 
 
 In all these instances we find that the organ which is called into 
 activity is excited by the direct application of some stimulus to its 
 own tissues. But this is not usually the manner in which the dif- 
 ferent functions are excited during life. The stimulus which calls 
 into action the organs of the living body is usually not direct, but 
 indirect in its operation. Generally speaking, the organs which are 
 situated in distant parts are connected with each other by such a 
 sympathy, that the activity of one is influenced by the condition of 
 the others. The muscles, for example, are almost never called into 
 action by an external stimulus operating directly upon their own 
 fibres, but by one which is applied to some other organ, either adja- 
 cent or remote. Thus the peristaltic action of the muscular coat of 
 the intestine commences when the food is brought in contact with 
 its mucous membrane. The lachrymal gland is excited to an in- 
 creased activity by anything which causes irritation of the conjunc- 
 
OF THE NERVOUS SYSTEM. 307 
 
 tiva. In all such instances, the physiological connection between 
 two different organs is established through the medium of the 
 nervous system. 
 
 The function of the nervous system may therefore be defined, in 
 the simplest terms, as follows : It is intended to associate the different 
 parts of the body in such a manner^ that an action may be excited in one 
 organ by means of a stimulus applied to another. 
 
 The instances of this mode of action are exceedingly numerous. 
 Thus, the light which falls upon the retina produces a contraction 
 of the pupil. The presence of food in the stomach causes the gall- 
 bladder to discharge its contents into the duodenum. The expul- 
 sive efforts of coughing are excited by a foreign body entangled in 
 the glottis. 
 
 It is easy to understand the great importance of this function, 
 particularly in the higher animals and in man, whose organization 
 is an exceedingly complicated one. For the different organs of the 
 body, in order to preserve the integrity of the whole frame, must 
 not only act and perform their functions, but they must act in har- 
 mony with each other, and at the right time, and in the right direc- 
 tion. The functions of circulation, of respiration, and of digestion, 
 are so mutually dependent, that if their actions do not take place 
 harmoniously, and in proper order, a serious disturbance must 
 inevitably follow. When the muscular system is excited by unu- 
 sual exertion, the circulation is also quickened. The blood arrives 
 more rapidly at the heart, and is sent in greater quantity to the 
 lungs. If the movements of respiration were not accelerated, at 
 the same time, through the connections of the nervous system, there 
 would immediately follow deficiency of aeration, pulmonary conges- 
 tion, and accumulation of blood on the right side of the heart. If 
 the iris were not stimulated to contract by the influence of the light 
 falling on the retina, the delicate expansion of the optic nerve 
 would be dazzled by any unusual brilliancy, and vision would be 
 obscured or confused. In all the higher animals, therefore, where 
 the different functions of the body are performed by distinct organs, 
 situated in different parts of the frame, it is necessary that their 
 action should be thus regulated and harmonized by the operation 
 of the nervous system. 
 
 The manner in which this is accomplished is as follows: — 
 The nervous system, however simple or however complicated it 
 may be, consists always of two different kinds of tissue, which are 
 
308 GENERAL STRUCTURE AND FUNCTIONS 
 
 distinguished from each other by their color, their structure, and 
 their mode of action. One of these is known as the white substance, 
 or i\iQ fibrous tissue. It constitutes the whole of the substance of the 
 nervous trunks and branches, and is found in large quantity on the 
 exterior ot the spinal cord, and in the central parts of the brain 
 and cerebellum. In the latter situations, it is of a soft consistency, 
 like curdled cream, and of a uniform, opaque white color. In 
 the trunks and branches of the nerves it has the same opaque 
 white color, but is at the same time of a firmer consistency, owing 
 to its being mingled with condensed areolar tissue. Examined by 
 the microscope, the white substance is seen to be composed every- 
 where of minute fibres or filaments, the "ultimate nervous fila- 
 ments," running in a direction very nearly parallel with each other. 
 These filaments are cylindrical in shape, and vary considerably in 
 size. Those which are met with in the spinal cord and the brain 
 are the smallest, and have an average diameter of yo^oo of an 
 inch. In the trunks and branches of the nerves they average ^^^-^ 
 of an inch. 
 
 The structure of the ultimate nervous filament is as follows: 
 The exterior of each filament consists of a colorless, transparent 
 tubular membrane, which is seen with some difficulty in the natural 
 condition of the fibre, owing to the extreme delicacy of its texture, 
 and to its cavity being completely filled with a substance yerj 
 similar to it in refractive power. In the interior of this tubular 
 membrane there is contained a thick, softish, semi-fluid nervous 
 matter, which is white and glistening by reflected light, and is 
 called the "white substance of Schwann." Finally, running longi- 
 tudinally through the central part of each filament, is a narrow 
 ribbon-shaped cord, of rather firm consistency, and of a semi- 
 transparent grayish color. This central portion is called the "axis 
 cylinder," or the " flattened band." It is enveloped everywhere by 
 the semi-fluid white substance, and the whole invested by the ex- 
 ternal tubular membrane. 
 
 When nervous matter is prepared for the microscope and exa- 
 mined by transmitted light, two remarkable appearances are 
 observed in its filaments, produced by the contact of foreign sub- 
 stances. In the first place the unequal pressure, to which the fila- 
 ments are accidentally subjected in the process of dissection and 
 preparation, produces an irregularly bulging or varicose appearance 
 in them at various points, owing to the readiness with which the 
 
OF THE NERVOUS SYSTEM. 
 
 309 
 
 Nervous Filaments from white substance of 
 brain. — a, a, a. Soft substance of the filaments pressed 
 out, and floating in irregularly rounded drops. 
 
 semi-fluid white substance in their interior is displaced in different 
 directions. (Fig. 118.) Sometimes spots may be seen here and 
 there, where the nervous 
 matter has been entirely 
 pressed apart in the centre 
 of a filament, so that there 
 appears to be an entire break 
 in its continuity, while the 
 investing membrane may be 
 still seen, passing across from 
 one portion to the other. 
 When a nervous filament is 
 torn across under the micro- 
 scope and subjected to pres 
 sure, a certain quantity of the 
 semi-fluid white substance is 
 pressed out from its torn 
 extremity, and may be en- 
 tirely separated from it, so 
 as to present itself under the 
 
 form of irregularly rounded drops of various sizes (a, a, a), scat- 
 tered over the field of the microscope. The varicose appearance 
 above alluded to is more frequently seen in the smaller nervous 
 filaments from the brain and spinal cord, owing to their soft con- 
 sistency and the readiness with which they yield to pressure. 
 
 The second effect produced by the artificial preparation of the 
 nervous matter is a partial coagulation of the white substance of 
 Schv/ann. In its natural condition this substance has the same 
 consistency throughout, and appears perfectly transparent and 
 homogeneous by transmitted light. As soon, however, as the nerv- 
 ous filament is removed from its natural situation, and brought in 
 contact with air, water, or other unnatural fluids, the soft substance 
 immediately under the investing membrane begins to coagulate. 
 It increases in consistency, and at the same time becomes more 
 highly refractive ; so that it presents on each side, immediately 
 underneath the investing membrane, a thin layer of a peculiar 
 glistening aspect. (Fig. 119.) At first, this change takes place 
 only in the outer portions of the white substance of Schwann. 
 The coagulating process, however, subsequently goes on, and 
 gradually advances from the edges of the filament toward its 
 
310 
 
 GENERAL STRUCTURE AND FUNCTIONS 
 
 centre, until its entire thickness after a time presents the same ap- 
 pearance. The effect of the same process can also be seen in those 
 
 portions of the white sub- 
 stance which have been 
 pressed out from the interior 
 of the filaments, and which 
 float about in the form of 
 drops. (Fig. 118, a.) These 
 drops are always covered 
 with a layer of coagulated 
 material which is thicker 
 and more opaque in propor- 
 tion to the length of time 
 which has elapsed since the 
 commencement of the alter- 
 ation. 
 
 The nervous filaments 
 have essentially the same 
 structure in the brain and 
 spinal cord as in the nervous 
 trunks and branches; only 
 they are of much smaller 
 size in the former than in the 
 latter situation. In the nervous trunks and branches, however, 
 outside the cranial and spinal cavities, there exists, superadded to 
 the nervous filaments and interwoven with them, a large amount of 
 ordinary areolar or fibrous tissue, which protects them from injury, 
 and gives to this portion of the nervous system a peculiar density 
 and resistance. This difference in consistency between the white sub- 
 stance of the nerves and that of the brain and spinal cord is owing, 
 therefore, exclusively to the presence of ordinary fibrous tissue in 
 the nerves, while it is wanting in the brain and spinal cord. The 
 consistency of the nervous filaments themselves is the same in 
 each situation. 
 
 The nervous filaments are arranged, in the nervous trunks and 
 branches, in a direction nearly parallel with each other. A certain 
 number of them are collected in the form of a bundle, which is 
 invested with a layer of fibrous tissue, in which run the small 
 bloodvessels, destined for the nutrition of the nerve. These pri- 
 mary bundles are united again into secondary, the secondary into 
 tertiary, &;c. A nerve, therefore, consists of a large bundle of ulti- 
 
 Nhrvohs Filaments from sciatic nerve, showing 
 their coagulation. — At a, the torn extremity of a 
 nervous filament with the axis cylindA' (6) protruding 
 from it. At c, the white substance of Schwann is nearly 
 separated by accidental compression, but the axis- 
 cyliuder passes across the ruptured portion. The out- 
 line of the tubular membrane is also seen at c on the 
 outside of the nervous filament. 
 
OF THE NERVOUS SYSTEM. 
 
 311 
 
 mate filaments, associated with each other in larger or smaller 
 packets, and bound together by the investing fibrous layers. When 
 a nerve is said to become branch- 
 ed or " divided" in any part of 
 its course, this division merely 
 implies that some of its filaments 
 leave the bundles with which 
 they were previously associated, 
 and pursue a different direction. 
 (Fig. 120.) A nerve which ori- 
 ginates, for example, from the 
 spinal cord in the region- of the 
 neck, and runs down the upper 
 extremity, dividing and subdivid- 
 ing, to be finally distributed to 
 the integument and muscles of 
 the hand, contains at its point of 
 (jrigin all the filaments into which 
 it is afterward divided, and which 
 are merely separated at succes- 
 sive points from the main bundle. 
 The ultimate filaments, accord- 
 ingly, are continuous throughout, 
 and do not themselves divide at 
 any point between their origin 
 and their final distribution. 
 
 When a nerve, furthermore, is 
 said to "inosculate" with another nerve, as when the infra-orbital 
 inosculates with the facial, or the cervical nerves inosculate with 
 each other, this means simply that some of the filaments composing 
 the first nervous bundle separate from it, and cross over to form a 
 part of the second, while some of those belonging to the second 
 cross over and join the first (Fig. 121); but the individual filaments 
 in each instance remain continuous and preserve their identity 
 throughout. This fact is of great physiological importance ; since 
 the white or fibrous nerve-substance is everywhere simply an 
 organ of transmission. It serves to convey the nervous impulse in 
 various directions, from without inward, or from within outward ; 
 and as each nervous filament acts independently of the others, it 
 will convey an impression or a stimulus continuously from its 
 origin to its termination, and will always have the same character 
 and function in every part of its course. 
 
 Division of a Nerve, showiug portioa of 
 nervous trunk {a), and the separation of its 
 filaments (6, c, d, e). 
 
312 
 
 GENERAL STRUCTURE AND FUNCTIONS 
 
 The other variety of nervous matter is known as the gray sub- 
 stance. It is sometimes called " cineritious matter," and sometimes 
 
 Fig. 121. 
 
 Inosculatiou of Nerves. 
 
 " vesicular neurine," It is found in the central parts of the spinal 
 cord, at the base of the brain in isolated masses, and is also spread 
 out as a continuous layer on the external portions of the cerebrum 
 and cerebellum. It also constitutes the substance of all the gan- 
 glia of the great syrapathe- 
 
 Fig. 122. 
 
 Nerve Cells, intermingled witli fibres; from 
 teiiiilunar ganglion of cat. 
 
 tic. Examined by the micro- 
 scope, it consists of vesicles 
 or cells, of various forms and 
 sizes, imbedded in a grayish, 
 granular, intercellular sub- 
 stance, and containing also, 
 very frequently, granules of 
 grayish pigmentary matter. 
 It is to the presence of this 
 granular pigment that this 
 kind of nervous matter owes 
 the ashy or "cineritious" color 
 from which it derives its 
 name. The cells composing 
 it vary in size, according to 
 
OF THE NERVOUS SYSTEM. 313 
 
 Kolliker, from -^-q^^ to -^^jj of an inch. The largest of them have 
 a very distinct nucleus and nucleolus. (Fig. 122.) Many of them 
 are provided with long processes or projections, which are some- 
 times divided into two or three smaller branches. These cells are 
 intermingled, in all the collections of gray matter, with nervous 
 filaments, and are entangled with their extremities in such a man- 
 ner that it is exceedingly difficult to ascertain the exact nature of 
 the anatomical relations existing between them. It is certain that 
 in some instances the slender processes running out from the nerv- 
 ous vesicles become at last continuous with the filaments ; but it is 
 not known whether this be the case in all or even in a majority of 
 instances. The extremities of the filaments, however, are at all 
 events brought into very close relation with the vesicles or cells of 
 the gray matter. 
 
 Every collection of gray matter, whatever be its situation or 
 relative size in the nervous system, is called a ganglion or nervous 
 centre. Its function is to receive impressions conveyed to it by the 
 nervous filaments, and to send out by them impulses which are to 
 be transmitted to distant organs. The ganglia, therefore, originate 
 nervous power, so to speak ; while the filaments and the nerves 
 only transmit it. Now we shall find that, in the structure of every 
 nervous system, the ganglia are connected, first with the different 
 organs, by bundles of filaments which are called nerves; and secondly 
 with each other, by other bundles which are termed commissures. 
 The entire system is accordingly made up of ganglia^ nerves^ and 
 commissures. 
 
 The simplest form of nervous system is probably that found in 
 the five-rayed starfish. This animal belongs to the type known 
 as radiata; that is, animals whose 
 organs radiate from a central point, Pi?- 123. 
 
 so as to form a circular series of 
 similar parts, each organ being re- 
 peated at different points of the 
 circumference. The starfish (Fig. 
 123) consists of a central mass, 
 with five arms or limbs radiating 
 from it. In the centre is the mouth, 
 and immediately beneath it the sto- 
 mach or digestive cavity, which 
 sends prolongations into every one 
 of the projecting limbs. There is 
 also contained in each limb a portion n^hvocs system of starp,. 
 
314 GENERAL STRUCTURE AND FUNCTIONS 
 
 of the glandular and muscular systems, and the whole is covered 
 by a sensitive integument. The nervous system consists of five 
 similar ganglia, situated in the central portion, at the base of the 
 arms. These ganglia are connected with each other by commis- 
 sures, so as to form a nervous collar or chain, surrounding the 
 orifice of the digestive cavity. Each ganglion also sends off nerves, 
 the filaments of which are distributed to the organs contained in 
 the corresponding limb. 
 
 We have already stated that the proper function of the nervous 
 system is to enable a stimulus, acting upon one organ, to produce 
 motion or excitement in another. This is accomplished, in the 
 starfish, in the following manner: — 
 
 When any stimulus or irritation is applied to the integument of 
 one of the arms, it is transmitted by the nerves of the integument 
 to the ganglion situated near the mouth. Arrived here, it is 
 received by the gray matter of the ganglion, and immediately con- 
 verted into an impulse which is sent out by other filaments to the 
 muscles of the corresponding limb; and a muscular contraction and 
 movement consequently take place. The muscles therefore contract 
 in consequence of an irritation which has been applied to the skin. 
 This is called the "reflex action" of the nervous system; because the 
 stimulus is first sent inward by the nerves of the integument, and 
 then returned or reflected back from the ganglion upon the muscles. 
 It must be recollected that this action does not necessarily indicate 
 any sensation or volition, nor even any consciousness on the part of 
 the animal. The function of the gray matter is simply to receive 
 the impulse conveyed to it, and to reflect or send back another ; and 
 this may be accomplished altogether involuntarily, and without the 
 existence of any conscious perception. 
 
 Where the irritation applied to the integument is of an ordinary 
 character and not very intense, it is simply reflected, as above 
 described, from the corresponding ganglion back to the same limb. 
 But if it be of a peculiar character, or of greater intensity than usual, 
 it may be also transmitted by the commissures to the neighboring 
 ganglia; and so two, three, four, or even all five of the limbs may 
 be set in motion by a stimulus applied to the integument of one of 
 them. Now, as all the limbs of the animal have the same structure 
 and contain the same organs, their action will also be the same ; 
 and the effect of this communication of the stimulus from one to 
 the other by means of commissures will be a repetition, or rather 
 a simultaneous production of similar movements in different parts 
 
OF THE NERVOUS SYSTEM. 
 
 315 
 
 of the body. According to the character and intensity, therefore, 
 of the original stimulus, it will be followed by a response from 
 one, several, or all of the different parts of the animal frame. 
 
 It will be seen also that there are two kinds of nervous filaments, 
 differing essentially in their functions. One set of these fibres run 
 from the sensitive surfaces to the ganglion, and convey the nervous 
 impression inward. These are called sensitive fibres. The other set 
 run from the ganglion to the muscles, and carry the nervous im- 
 pression outward. These are called motor fibres. 
 
 In the starfish, wbere the body is composed of a repetition of simi- 
 lar parts arranged round a common centre, and where all the limbs 
 are precisely alike in structure, the several ganglia composing the 
 nervous system are also similar to each other, and act in the same 
 way. But in animals which are constructed upon a different plan, 
 and whose bodies are composed of distinct organs, situated in dif- 
 ferent regions, we find that the nervous ganglia, presiding over 
 the function of these organs, present a corresponding degree of 
 dissimilarity. 
 
 In Ajylysia, for example, which belongs to the type of mollusca, 
 or soft-bodied animals, the digestive apparatus consists of a mouth, 
 an oesophagus, a triple stomach, and a somewhat convoluted intes- 
 tine. The liver is large, and placed on one side of the body, while 
 the gills, in the form of vascular laminae, occupy the opposite side. 
 There are both testicles and ovaries in the same animal, the male 
 and female functions co-existing, as in many 
 other invertebrate species. All the organs, 
 furthermore, are here arranged without any 
 reference to a regular or symmetrical plan. 
 The body is covered with a muscular man- 
 tle, which expands at the ventral surface 
 into a tolerably well developed " foot," or 
 organ of locomotion, by whicb the animal 
 is enabled to change its position and move 
 from one locality to another. 
 
 The nervous system of this animal is con- 
 structed upon a plan corresponding with 
 that of the entire body. (Fig. 124.) There 
 is a small ganglion (i) situated anteriorly, 
 which sends nerves to the commencement nervol-s svstem of 
 of the digestive apparatus, and is regarded i^pL^itua^. "rrL;. 
 as the oesophageal or digestive ganglion, i^r^^i gangUon. 3.3. Pedai or 
 
 T J'il l_l-T-^- 1 /x locomotory ganglia -t. Respi- 
 
 Immeaiately behmd it is a larger one (i) latory ganguou. 
 
 Fig. 124. 
 
316 
 
 GENERAL STRUCTURE AND FUNCTIONS 
 
 Fig. 125. 
 
 called the cephalic or cerebral ganglion, which sends nerves to the 
 organs of special sense, and which is regarded as the seat of volition 
 and general sensation for the entire body. Following this is a pair 
 of ganglia (3, s), the pedal or locomotory ganglia, which supply the 
 muscular mantle and its foot-like expansion, and which regulate the 
 movement of these organs. Finally, another ganglion (4), situated 
 at the posterior part of the body, sends nerves to the branchiae or 
 gills, and is termed the branchial or respiratory ganglion. All 
 these nervous centres are connected by commissures with the central 
 or cerebral ganglion, and may therefore act either independently or 
 in association with each other, by means of these connecting fibres. 
 In the third type of animals, again, viz., the articulata, the gene- 
 ral plan of structure of the body is different from the foregoing, 
 and the nervous system is accordingly modified to correspond with 
 it. In these animals, the body is composed of a number of rings 
 or sections, which are articulated with each other in linear series. 
 A very good example of this type may be found in the common 
 centipede, or scolopendra. Here the body is com- 
 posed of twenty-two successive and nearly simi- 
 lar articulations, each of which has a pair of legs 
 attached, and contains a portion of the glandular, 
 respiratory, digestive and reproductive appara- 
 tuses. The animal, therefore, consists of a repe- 
 tition of similar compound parts, arranged in a 
 longitudinal chain or series. The only exceptions 
 to this similarity are in the first and last articula- 
 tions. The first is large, and contains the mouth; 
 the last is small, and contains the anus. The first 
 articulation, which is called the "head," is also 
 furnished with eyes, with antennae, and with a 
 pair of jaws, or mandibles. 
 
 The nervous system of the centipede (Fig. 125), 
 corresponding in structure with the above plan, 
 consists of a linear series of nearly equal and 
 similar ganglia arranged in pairs, situated upon 
 the median line, along the ventral surface of the 
 alimentary canal. Each pair of ganglia is con- 
 nected with the integument and muscles of its 
 own articulation by sensitive and motor filaments ; 
 and with those which precede and follow by a 
 double cord of lonojitudinal commissural fibres. In the first articu- 
 
 NERVons System 
 OF Centipede. 
 
OF THE NERVOUS SYSTEM. 317 
 
 lation, moreover, or the head, the ganglia are larger than elsewhere, 
 and send nerves to the antennae and to the organs of special sense. 
 This pair is termed the cerebral ganglion, or the " brain." 
 
 A reflex action may take place, in these animals, through either 
 one or all of the ganglia composing the nervous chain. An 
 impression received bj the integument of any part of the body 
 may be transmitted inward to its own ganglion and thence reflected 
 immediately outward, so as to produce a movement of the limbs 
 belonging to that articulation alone; or it may be propagated, 
 through the longitudinal commissures, forward or back, and pro- 
 duce simultaneous movements in several neighboring articulations; 
 or, finally, it may be propagated quite up to the anterior pair of 
 ganglia, or "brain," where its reception will be accompanied with 
 consciousness, and a voluntary movement reflected back upon any 
 or all of the limbs at once. The organs of special sense, also, com- 
 municate directly with the cerebral ganglia; and impressions con- 
 veyed through them may accordingly give rise to movements in 
 any distant part of the body. In these animals the ventral ganglia, 
 or those which simply stand as a medium of communication be- 
 tween the integument and the muscles, are nearly similar through- 
 out; while the first pair, or those which receive the nerves of special 
 sense, and which exercise a general controlling power over the rest 
 of the nervous system, are distinguished from the remainder by a 
 well-marked preponderance in size. 
 
 In the centipede it will be noticed that nearly all the organs and 
 functions are distributed in an equal degree throughout the whole 
 length of the body. The organs of special sense alone, with those 
 of mastication and the functions of perception and volition, are 
 confined to the head. The ganglia occupying this part are there- 
 fore the only ones which are distinguished by any external pecu- 
 liarities; the remainder being nearly uniform both in size and 
 activity. In some kinds of articulated animals, however, particular 
 functions are concentrated, to a greater or less extent, in particular 
 parts of the body ; and the nervous ganglia which preside over 
 them are modified in a corresponding manner. In the insects, 
 for example, the body is divided into three distinct sections, viz : 
 the head, containing the organs of prehension, mastication, tact 
 and special sense ; the chest, upon which are concentrated the or- 
 gans of locomotion, the legs and wings; and the abdomen, contain- 
 ing the greater part of the alimentary canal, together with the 
 glandular and generative organs. As the insects have a greater 
 
318 GENERAL STRUCTURE AND FUNCTIONS 
 
 amount of intelligence and activity, than the centipedes and other 
 worm-like articulata, and as the organs of special sense are more 
 perfect in them, the cerebral ganglia are also unusually developed, and 
 are evidently composed of several pairs, connected by commissures 
 so as to form a compound mass. As the organs of locomotion, fur- 
 thermore, instead of being distributed, as in the centipede, through- 
 out the entire length of the animal, are concentrated upon the chest, 
 the locomotory ganglia also preponderate in size in this region of 
 the body ; while the ganglia which preside over the secretory and 
 generative functions are situated together, in the cavity of the ab- 
 domen. 
 
 All the above parts, however, are connected, in the same manner 
 as previously described, with the anterior or cerebral pair of gan- 
 glia. In all articulate animals, moreover, the general arrangement 
 of the body is symmetrical. The right side is, for the most part, 
 precisely like the left, as well in the internal organs as in the ex- 
 ternal covering and the locomotory appendages. The only marked 
 variation between different parts of the body is in an antero-pos- 
 terior direction ; owing to difierent organs being concentrated, in 
 some cases, in the head, chest, and abdomen. 
 
 Finally, in the vertebrate type of animals, comprising man, the 
 quadrupeds, birds, reptiles and fish, the external parts of the body, 
 togetlier with the locomotory apparatus and the organs of special 
 sense, are symmetrical, as in the articulata; but the internal organs, 
 especially those concerned in the digestive and secretory functions, 
 are unsymraetrical and irregular, as in the molluscs. The organs 
 of respiration, however, are nearly symmetrical in the vertebrata, 
 for the reason that the respiratory movements, upon which the 
 function of these organs is immediately dependent, are performed 
 by muscles belonging to the general locomotory apparatus. The 
 nervous system of the vertebrata partakes, accordingly, of the 
 structural arrangement of the organs under its control. That por- 
 tion which presides over the locomotory, respiratory, sensitive, and 
 intellectual functions forms a system by itself, called the cerebro- 
 spinal, system. This system is arranged in a manner very similar to 
 that of the articulata. It is composed of two equal and symmetri- 
 cal halves, running along the median line of the body, the different 
 parts of which are connected by transverse and longitudinal com- 
 missures. Its ganglia occupy the cavities of the cranium and the 
 spinal canal, and send out their nerves through openings in the 
 bony walls of these cavities. 
 
OF THE NERVOUS SYSTEM. 
 
 319 
 
 Fig. 126. 
 
 The other portion of the nervous system of vertebrata is that 
 which presides over the functions of vegetative life. It is called 
 the ganglionic^ or great sympathetic system. Its ganglia are situated 
 anteriorly to the spinal column, in the visceral cavities of the body, 
 and are connected, like the others, by transverse and longitudinal 
 commissures. This part of the nervous system is symmetrical in 
 the neck and thorax, but is unsymmetrical in the abdomen, where 
 it attains its largest size and its most complete development. 
 
 The vertebrate animals, as a general rule, are very much superior 
 to the other classes, in intelligence and activity, as well as in the 
 variety and complicated character of their motions; while their 
 nutritive or vegetative functions, on the other hand, are not particu- 
 larly well developed. Accordingly we find that in these animals the 
 cerebro-spinal sj'^stem of nerves preponderates very much, in im- 
 portance and extent, over that of the great sympathetic. The quan- 
 tity of nervous matter contained in the brain and spinal cord is, even 
 in the lowest vertebrate animal, very much greater than that con- 
 tained in the system of the great 
 sympathetic; and this preponderance 
 increases, in the higher classes, just 
 in proportion to their superiority in 
 intelligence, sensation, power of mo- 
 tion, and other functions of a purely 
 animal character. 
 
 The spinal cord is very nearly 
 alike in the different classes of ver- 
 tebrate animals. It is a nearly 
 cylindrical cord, running from one 
 end of the spinal canal to the other, 
 and connected at its anterior ex- 
 tremity with the ganglia of the 
 brain. (Fig. 126.) It is divided, by 
 an anterior and posterior median 
 fissure, into two lateral halves, which 
 still remain connected with each 
 other by a central mass or commis- 
 sure. Its inner portions are occupied 
 by gray matter, which forms a con- 
 tinuous ganglionic chain, running cerebro-spi^al sy.tkm op max. 
 
 from one extremity of the cord to — l- cerebrum. 2. Cerebellum 3,3, .3. Spinal 
 .i ,■! -r . cord aad nerves. 4, 4. Brachial nerves. 
 
 the other. Its outer portions are 5, 5. sacrai nerves. 
 
320 
 
 GENERAL STRUCTURE AND FUNCTIONS 
 
 composed of white substance, the filaments of which run for the 
 most part in a longitudinal direction, connecting the different parts 
 of the cord with each other, and the cord itself with the ganglia 
 of the brain. 
 
 The spinal nerves are given off from the spinal cord at regular 
 intervals, and in symmetrical pairs; one pair to each successive 
 portion of the body. Their filaments are distributed to the integu- 
 ment and muscles of the corresponding regions. In serpents, where 
 locomotion is performed by simple, alternate, lateral movements 
 of the spinal column, the spinal cord and its nerves are of the 
 same size throughout. But in the other vertebrate classes, where 
 there exist special organs of locomotion, such as fore and hind 
 legs, wings, and the like, the spinal cord is increased in size at 
 the points where the nerves of these organs are given off; and the 
 nerves themselves, which supply the limbs, are larger than those 
 originating from other parts of the spinal cord. Thus, in the hu- 
 man subject (Fig. 126), the cervical nerves, which go to the arms, 
 and the sacral nerves, which are distributed to the legs, are larger 
 than the dorsal and lumbar nerves. They form also, by frequent 
 inosculation, two remarkable plexuses, before entering their corre- 
 sponding limbs, viz., the brachial plexus above, and the sacral 
 plexus below. The cord itself, moreover, presents two enlargements 
 at the point of origin of these nerves, viz., the cervical enlargement 
 from which the brachial nerves (4, 4) are given off, and the lum- 
 bar enlargement from which the sacral nerves (5, 5) originate. 
 If the spinal cord be examined in transverse section (Fig. 127), 
 
 it will be seen that the gray 
 Fig. 127. matter in its central portion 
 
 forms a double crescentic- 
 shaped mass, with the con- 
 cavity of the crescents turn- 
 ed outward. These crescentic 
 masses of gray matter, occu- 
 pying the two lateral halves 
 of the cord, are united with 
 each other by a transverse 
 band of the same substance, 
 which is called the gray 
 commissure of the cord. Di- 
 rectly in front of this is a 
 transverse band of white substance, connecting in a similar manner 
 
 Transverse Section of Spinal Cokd. — a,h. Spinal 
 nerves of right and left side, showing their two roots, 
 d. Origin of anterior root. e. Origin of posterior root. 
 c. Ganglion of posterior root. 
 
OF THE NERVOUS SYSTEM. 321 
 
 the white portions of the two lateral halves. It is called the white 
 commissure of the cord. 
 
 The spinal nerves originate from the cord on each side by two 
 distinct roots ; one anterior, and one posterior. The anterior root 
 (Fig. 127, d) arises from the surface of the cord near the extremity 
 of the anterior peak of gray matter. The posterior root (e) origi- 
 nates at the point corresponding with the posterior peak of gray 
 matter. Both roots are composed of a considerable number of 
 ultimate nervous filaments, united with each other in parallel 
 bundles. The posterior root is distinguished by the presence of a 
 small ganglion (c) which appears to be incorporated with it, and 
 through which its fibres pass. There is no such ganglion on the 
 anterior root. The two roots unite with each other shortly after 
 leaving the cavity of the spinal canal, and mingle their filaments 
 in a single trunk. 
 
 It will be seen, on referring to the diagram (Fig. 127), that each 
 lateral half of the spinal cord is divided into two portions, an 
 anterior and a posterior portion. The posterior peak of gray mat- 
 ter comes quite up to the surface of the cord, and it is just at this 
 point (e) that the posterior roots of the nerves have their origin. 
 The whole of the white substance included between this point and 
 the posterior median fissure is called the posterior column of the 
 cord. That which is included between the same point and the 
 anterior median fissure is the arderior column of the cord. The 
 white substance of the cord may then be regarded as consisting 
 for the most part of four longitudinal bundles of nervous filaments, 
 viz., the right and left anterior, and the right and left posterior 
 columns. The posterior median fissure penetrates deeply into the 
 substance of the cord, quite down to the gray matter, so that the 
 posterior columns appear entirely separated from each other in a 
 transverse section ; while the anterior median fissure is more shal- 
 low and stops short of the gray matter, so that the anterior columns 
 are connected with each other by the white commissure above men- 
 tioned. 
 
 By the encephalon we mean the whole of that portion of the 
 cerebro-spinal system which is contained in the cranial cavity. It 
 is divided into three principal parts, viz., the cerebrum, cerebellum, 
 and medulla oblongata. The anatomy of these parts, though some- 
 what complicated, can be readily understood if it be recollected 
 that they are simply a double series of nervous ganglia, connected luith 
 each other and with the spinal cord by transverse and longitudinal 
 21 
 
322 
 
 GENERAL STRUCTURE AND FUNCTIONS 
 
 commissures. The number and relative size of these ganglia, in 
 different kinds of animals, depend upon the perfection of the bodily 
 organization in general, and more especially on that of the intelli- 
 gence and the special senses. They are most readily described by 
 commencing with the simpler forms and terminating with the more 
 complex. 
 
 The brain of the Alligator (Fig. 128) consists of five pair of 
 ganglia, ranged one behind the other in the interior of the cranium. 
 
 The first of these are two rounded masses 
 (i), lying just above and behind the nasal 
 cavities, which distribute their nerves 
 upon the Schneiderian mucous mem- 
 brane. These are the olfactory ganglia. 
 They are connected with the rest of the 
 brain by two long and slender commis- 
 sures, the "olfactory commissures." The 
 next pair (2) are somewhat larger and of 
 a triangular shape, when viewed from 
 above downward. They are termed the 
 " cerebral ganglia," or the hemispheres. 
 Imm.ediately following them are two 
 quadrangular masses (3) which give ori- 
 gin to the optic nerves, and are called 
 therefore the optic ganglia. They are 
 termed also the "optic tubercles;" and 
 in some of the higher animals, where 
 they present an imperfect division into 
 four nearly equal parts, they are known as the " tubercula quadri- 
 gemina." Behind them, we have a single triangular collection 
 of nervous matter (4), which is called the cerebellum. Finally, the 
 upper portion of the cord, just behind and beneath the cerebellum, 
 is seen to be enlarged and spread out laterally, so as to form a 
 broad oblong mass (^), the medulla oblongata. It is from this latter 
 portion of the brain that the pneumogastric or respiratory nerves 
 originate, and its ganglia are therefore sometimes termed the "pneu- 
 mogastric" or " respiratory" ganglia. 
 
 It will be seen that the posterior columns of the cord, as they 
 diverge laterally, in order to form the medulla oblongata, leave be- 
 tween them an open space, which is continuous with the posterior 
 median fissure of the cord. This space is known as the " fourth 
 ventricle." It is partially covered in by the backward projection 
 
 Brain of Allioator. — 1. Ol- 
 factory ganglia. 2. Hemisplieres. 3. 
 Optic tubercles. 4. Cerebellum. 5. 
 
 Medulla oblongata. 
 
OF THE NERVOUS SYSTEM. 
 
 323 
 
 of the cerebellum, but in the alligator is still somewhat open pos- 
 teriorly, presenting a kind of chasm or gap between the two lateral 
 halves of the medulla oblongata. 
 
 The chain of ganglia which compose the brain, being arranged 
 in pairs as above described, are separated from each other on the 
 two sides by a longitudinal median fissure, which is continuous 
 with the posterior median fissure of the cord. In the brain of 
 the alligator this fissure appears to be interrupted at the cerebellum ; 
 but in the higher classes, where the lateral portions of the cere- 
 bellum are more highly developed, as in the human subject (Fig. 126), 
 they are also separated from each other posteriorly on the median 
 line, and the longitudinal median fissure is complete througbout. 
 
 In hirds^ the hemispheres are of much larger size than in rep- 
 tiles, and partially conceal th.e optic ganglia. The cerebellum, 
 also, is very well developed iu this class, and presents on its sur- 
 face a number of transverse foldings or convolutions, by which 
 the quantity of gray matter which it contains is considerably in- 
 creased. The cerebellum bere extends so far backward as almost 
 completely to conceal the medulla oblongata and the fourth ven- 
 tricle. 
 
 In the quadrupeds^ the hemispheres and cerebellum attain a still 
 greater size in proportion to the remaining parts of tbe brain. 
 There are also two other pairs 
 of ganglia, situated beneath the 
 hemispheres, and between them 
 and thetubercula quadrigemina. 
 These are the corpora striata in 
 front and the optic thalami behind. 
 In Fig. 129 is shown the brain of 
 the rabbit, with the hemispheres 
 laid open and turned aside, so as 
 to show the internal parts in their 
 natural situation. The olfactory 
 ganglia are seen in front (i) con- 
 nected with the remaining parts 
 by the olfactory commissures. 
 The separation of the hemispheres 
 (2,2) shows the corpora striata (3) 
 and the optic thalami (4). Then 
 come the tubercula quadrigemina 
 (5), which are here composed, as 
 
 Brain of Rabbit, vieived from above. — 
 1. Olfactory ganglia. 2. Hemispheres, turned 
 aside. 3. Corpora striata. 4. Optic thalami. 
 5. Tubercula quadrigemina. 6. Cerebellum. 
 
324 
 
 GENERAL STRUCTURE AND FUNCTIONS 
 
 above mentioned, of four rounded masses, nearly similar in size. The 
 cerebellum (e) is considerably enlarged by the development of its 
 lateral portions, and shows an abundance of transverse convolutions. 
 It conceals from view the fourth ventricle and most of the medulla 
 oblongata. 
 
 In other species of quadrupeds the hemispheres increase in size 
 so as to project entirely over the olfactory ganglia in front, and to 
 cover in the tubercula quadrigemina and the cerebellum behind. 
 The surface of the hemispheres also becomes covered with numer- 
 ous convolutions, which are curvilinear and somewhat irregular 
 in form and direction, instead of being transverse, like those of the 
 cerebellum. In man, the development of the hemispheres reaches 
 its highest point; so that they preponderate altogether in size over 
 the rest of the ganglia constituting the brain. In the human brain, 
 accordingly, when viewed from above downward, there is nothing 
 to be seen but the convex surfaces of the hemispheres ; and even 
 in a posterior view, as seen in Fig. 126, they conceal everything 
 but a portion of the cerebellum. All the remaining parts, how- 
 ever, exist even here, and have the same connections and relative 
 situation as in other instances. They may be best studied in the 
 following order. 
 
 As the spinal cord, in the human subject, passes upward into 
 the cranial cavity, it enlarges into the medulla oblongata as already 
 described. The medulla oblongata presents on each side three pro- 
 jections, two anterior and one posterior. The middle projections 
 on its anterior surface (Fig. 130, i, i), which 
 are called the anterior pyramds^ are the con- 
 tinuation of the anterior columns of the cord. 
 They pass onward, underneath the transverse 
 fibres of the pons Varolii, run upward to the 
 corpora striata, pass through these bodies, and 
 radiate upward and outward from their exter- 
 nal surface, to terminate in the gray matter of 
 the hemispheres. The projections immedi- 
 ately on the outside of the anterior pyramids, 
 in the medulla oblongata, are the olivary bodies 
 (2, 2). They contain in their interior a thin 
 layer of gray matter folded upon itself, the 
 functions and connections of which are but 
 little understood, and are not, apparently, of 
 very great importance. 
 
 Fis. 130. 
 
 Medclla Oblongata 
 OF Human Brain, ante- 
 rior view. — 1, 1. Anterior py- 
 ramids. 2, 2. Olivary bodies. 
 3, 3. Kestiform bodies. 4. De- 
 cussation of tlie anterior co- 
 lamns. The medulla oblong- 
 ata is seen terminated above 
 by the transverse fibres of the 
 pons Varolii. 
 
OF THE NERVOUS SYSTEM. 325 
 
 The anterior columns of the cord present, at the lower part of the 
 medulla oblongata, a remarkable interchange or crossing of their 
 fibres (4). The fibres of the left anterior column pass across the 
 median line at this spot, and becoming continuous with the right 
 anterior pyramid, are finally distributed to the right side of the 
 cerebrum; while the fibres of the right anterior column, passing 
 over to the left anterior pyramid, are distributed to the left side of 
 the cerebrum. This interchange or crossing of the nervous fibres 
 is known as the decussation of the anterior columns of the cord. 
 
 The posterior columns of the cord, as they diverge on eacli side 
 the fourth ventricle, form the posterior and lateral projections of 
 the medulla oblongata (3, 3). They are sometimes called the "resti- 
 form bodies," and are extremely important parts of the brain. 
 They consist in great measure of the longitudinal filaments of 
 the posterior columns, which pass upward and outward, and are 
 distributed partly to the gray matter of the cerebellum. The 
 remainder then pass forward, underneath the tubercula quadri- 
 gemina, into and through the optic thalami; and radiating thence 
 upward and outward, are distributed, like the continuation of the 
 anterior columns, to the gray matter of the cerebrum. The resti- 
 form bodies, however, in passing upward to the cerebellum, are 
 supplied with some fibres from the anterior columns of the cord, 
 which, leaving the lower portion of the anterior pyramids, join the 
 restiform bodies, and are distributed with them to the cerebellum. 
 From this description it will be seen that both the cerebrum and 
 the cerebellum are supplied with filaments from both the anterior 
 and posterior columns of the cord. 
 
 In the substance of each restiform body, moreover, there is im- 
 bedded a ganglion which gives origin to the pneumogastric nerve, 
 and presides over the functions of respiration. This ganglion is 
 surrounded and covered by the longitudinal fibres passing upward 
 from the cord to the cerebellum, but may be discovered by cutting 
 into the substance of the restiform body, in which it is buried. It 
 is the first important ganglion met with, in dissecting the brain 
 from below upward. 
 
 While the anterior columns are passing beneath the pons Varolii, 
 they form, together with the continuation of the posterior columns 
 and the transverse fibres of the pons itself, a rounded prominence 
 or tuberosity, which is known by the name of the tuher annulare. 
 In the deeper portions of this protuberance there is situated, among 
 the longitudinal fibres, another collection of gray matter, which. 
 
326 
 
 GENEEAL STRUCTURE AND FUNCTIONS 
 
 though not of large size, has very important functions and connec- 
 tions. This is known as the ganglion of the tuher annulare. 
 
 Situated almost immediately above these parts we have the cor- 
 pora striata in front, and the optic thalami behind, nearly equal in 
 size, and giving passage, as above described, to the fibres of the 
 anterior and posterior columns. Behind them still, and on a little 
 lower level, are the tubercula quadrigemina, giving origin to the 
 optic nerves. The olfactory ganglia rest upon the cribriform plate 
 of the ethmoid bone, and send the olfactory filaments through the 
 perforations in this plate, to be distributed upon the mucous mem- 
 brane of the upper and middle turbinated bones. The cerebellum 
 covers in the fourth ventricle and the posterior surface of the 
 medulla oblongata ; and finally the cerebrum, which has attained 
 'the size of the largest ganglion in the cranial cavity, extends so far 
 in all directions, forward, backward, and laterally, as to form a con- 
 voluted arch or vault, completely covering all the remaining parts 
 of the encephalon. 
 
 The entire brain may therefore be regarded as a connected series 
 of ganglia, the arrangement of which is shown in the accompany- 
 ing diagram. (Fig. 131.) These 
 ^ig-l^l- ganglia occur in the following 
 
 order, counting from before back- 
 ward: 1st. The olfactory gan- 
 glia. 2d. The cerebrum or hemi- 
 spheres. 3d. The corpora striata. 
 4th. The optic thalami. 5th. The 
 tubercula quadrigemina. 6th. 
 The cerebellum. 7th. The gan- 
 glion of the tuber annulare. And 
 8th. The ganglion of the medulla 
 oblongata. Of these ganglia, 
 only the hemispheres and cere- 
 bellum are convoluted, while the 
 remainder are smooth and round- 
 ed or somewhat irregular in 
 shape. The course of the fibres 
 coming from the anterior and 
 posterior columns of the cord is also to be seen in the accompany- 
 ing figure. A portion of the anterior fibres, we have already ob- 
 served, pass upward and backward, with the restiform bodies, to the 
 cerebellum ; while the remainder run forward through the tuber 
 
 Diagram of Human Brain, in vertical sec- 
 tion ; ijhowi;ig the situation of the different gan- 
 glia, and the course of the fihres. 1 Olfactory 
 g:inglion. 2. Hemisphere. 3. Corpus striatum. 
 4. ijptic thalamus. .'5. Tubercula quadrigemina. 
 6. Cerebellum. 7. Ganglion of tuber annulare. 
 8. Ganglion of medulla oblongata. 
 
OF THE NERVOUS SYSTEM. 327 
 
 annulare and the corpus striatum, and then radiate to the gray- 
 matter of the cerebrum. The posterior fibres, constituting the res- 
 tiform body, are distributed partly to the cerebellum, and then pass 
 forward, as previously described, underneath the tubercula quadri- 
 gemina to the optic thalami, whence they are also finally distributed 
 to the gray matter of the cerebrum. 
 
 The cerebrum and cerebellum, each of which is divided into two 
 lateral halves or " lobes," by the great longitudinal fissure, are both 
 provided with transverse commissures, by which a connection is 
 established between their right and left sides. The great trans- 
 verse commissure of the cerebrum is that layer of white substance 
 which is situated at the bottom of the longitudinal fissure, and 
 which is generally known by the name of the " corpus callosum." 
 Tt consists of nervous filaments, which originate from the gray 
 matter of one hemisphere, converge to the centre where they be- 
 come parallel, cross the median line, and are finally distributed to 
 the corresponding parts of the hemisphere upon the opposite side. 
 The transverse commissure of the cerebellum is the pons Varolii. 
 Its fibres converge from the gray matter of the cerebellum on one 
 side, and pass across to the opposite ; encircling the tuber annulare 
 with a band of parallel curved fibres, to which the name of " pons 
 Varolii" has been given from their resemblance to an arched bridge. 
 
 The cerebro-spinal system, therefore, consists of a series of gan- 
 glia situated in the cranio-spinal cavities, connected with each other 
 by transverse and longitudinal commissures, and sending out nerves 
 to the corresponding parts of the body. The spinal cord supplies 
 the integument and muscles of the neck, trunk, and extremities ; 
 while the ganglia of the brain, beside supplying the corresponding 
 parts of the head, preside also over the organs of special sense, and 
 perform various other functions of a purely nervous character. 
 
328 OF NERVOUS IRRITABILITY 
 
 CHAPTETl II. 
 
 OF NERVOUS IRRITABILITY AND ITS MODE OF 
 
 ACTION. 
 
 We have already mentioned, in a previous chapter, that every 
 organ in the body is endowed with the property o^ irritability ; that 
 is, the property of reacting in some peculiar manner when subjected 
 to the action of a direct stimulus. Thus the irritability of a gland 
 shows itself by increased secretion, that of the capillary vessels by 
 congestion, that of the muscles by contraction. Now the irritability 
 of the muscles, indicated as above by their contraction, is extremely 
 serviceable as a means of studying and exhibiting nervous pheno- 
 mena. We shall therefore commence this chapter by a study of 
 some of the more important facts relating to muscular irritability. 
 
 The irritability of the muscles is a 'property inherent in the mvscular 
 fibre itself. The existence of muscular irritability cannot be ex- 
 plained on any known physical or chemical laws, so far as they 
 relate to inorganic substances. It must be regarded simply as a 
 peculiar property, directly dependent on the structure and consti- 
 tution of the muscular fibre; just as the property of emitting light 
 belongs to phosphorus, or that of combining with metals to oxygen. 
 This property may be called into action by various kinds of stimu- 
 lus; as by pinching the muscular fibre, or pricking it with the point 
 of a needle, the application of an acid or alkaline solution, or the 
 discharge of a galvanic battery. All these irritating applications 
 are immediately followed by contraction of the muscular fibre. 
 This contraction will even take place under the microscope, when 
 the fibre is entirely isolated, and removed from contact with any 
 other tissue ; showing that the properties of contraction and irrita- 
 bility reside in the fibre itself, and are not communicated to it by 
 other parts. 
 
 Muscular irritability continues for a certain time after death. The 
 stoppage of respiration and circulation does not at once destroy 
 the vital properties of the tissues, but nearly all of them retain 
 these properties to a certain extent for some time afterward. It is 
 only when the constitution of the tissues has become altered by 
 
AND ITS MODE OF ACTION. 
 
 329 
 
 being deprived of blood, and by the consequent derangement of 
 the nutritive process, that their characteristic properties are finally 
 lost. Thus, in the muscles, irritability and contractility may be 
 easily shown to exist for a short time after death by applying to the 
 exposed muscular fibre the same kind of stimulus that we have 
 already found to affect it during life. It is easy to see, in the 
 muscles of the ox, after the animal has been killed, flayed, and 
 eviscerated, different bundles of muscular fiibres contracting irregu- 
 larly for a long time, where they are exposed to the contact of the 
 air. Even in the human subject the same phenomenon may be 
 seen in cases of amputation; the exposed muscles of the amputated 
 limb frequently twitching and quivering for many minutes after 
 their separation from the body. 
 
 The duration of muscular irritability, after death, varies consi- 
 derably in different classes of animals. It disappears most rapidly 
 in those whose circulation and respiration are naturally the most 
 active; while it continues for a longer time in those whose circula- 
 tion and respiration are sluggish. Thus the muscular irritability 
 in birds continues only a few minutes after the death of the ani- 
 mal. That of quadrupeds lasts somewhat longer ; while in reptiles 
 it remains, under favorable circumstances, for many hours. The 
 cause of this difference is probably that in birds and quadrupeds, 
 the tissues being very vascular, and the molecular changes of nu- 
 trition going on with rapidity, the constitution of the muscular 
 fibre becomes so rapidl}'^ altered after the circula- 
 tion has ceased, that its irritability soon disap- 
 pears. In reptiles, on the other hand, the tissues 
 are less vascular than in birds and quadrupeds, 
 and all the nutritive changes go on more slowly. 
 Eespiration and circulation can therefore be dis- 
 pensed with for a longer period, before the consti- 
 tution of the tissues becomes so much altered as 
 to destroy altogether their vital properties. 
 
 Owing to this peculiarity of the cold-blooded 
 animals, their tissues may be used with great ad- 
 vantage for purposes of experiment. If a frog's 
 leg, for example, be separated from the body of 
 the animal (Fig. 132), the skin removed, and the 
 poles of a galvanic apparatus applied to the sur- frog's leo, 
 face of the muscle (a, b), a contraction takes place "^''"^ po'<^^ °^ s'^'- 
 
 1 . . . 1 1 1 T ^ vanic battery applied 
 
 every time the circuit is completed and a discharge to the muscles at a, 6. 
 
 Fig. 132. 
 
330 OF NERVOUS IRRITABILITY 
 
 passed through the tissues of the limb. The leg of the frog, pre- 
 pared in this way, may be employed for a long time for the pur- 
 pose of exhibiting the effect of various kinds of stimulus upon the 
 muscles. All the mechanical and chemical irritants which we 
 have mentioned, pricking, pinching, cauterizing, galvanism, &c., act 
 with more or less energy and promptitude, though the most efficient 
 of all is the electric discharge. 
 
 Continued irritation exhausts the irritability of the muscles. It is 
 found that the irritability of the muscles wears out after death more 
 rapidly if they be artificially excited, than if they be allowed to 
 remain at rest. During life, the only habitual excitement of mus- 
 cular contraction is the peculiar stimulus conveyed by the nerves. 
 After death this stimulus may be replaced or imitated, to a certain 
 extent, by other irritants ; but their application gradually exhausts 
 the contractility of the muscle and hastens its final disappearance. 
 Under ordinary circumstances, the post-mortem irritability of the 
 muscle remains until the commencement of cadaveric rigidity. 
 When this has become fairly established, the muscles will no longer 
 contract under the application of an artificial stimulus. 
 
 Certain poisonous substances have the power of destroying the 
 irritability of the muscles by a direct action upon their tissue. 
 Sulpho-cyanide of potassium, for example, introduced into the cir- 
 culation in sufficient quantity to cause death, destroys entirely the 
 muscular irritability, so that no contraction can afterward be pro- 
 duced by the application of an external stimulant. 
 
 Nervous Irritability. — The irritability of the nerves is the pro- 
 perty by which they may be excited by an external stimulus, so as 
 to be called into activity and excite in their turn other organs to 
 which their filaments are distributed. When a nerve is irritated, 
 therefore, its power of reaction, or its irritability, can only be esti- 
 mated by the degree of excitement produced in the organ to which the 
 nerve is distributed. A nerve running from the integument to the 
 brain produces, when irritated, a painful sensation ; one distributed 
 to a glandular organ produces increased secretion ; one distributed 
 to a muscle produces contraction. Of all these effects, muscular 
 contraction is found to be the best test and measure of nervous 
 irritability, for purposes of experiment. Sensation cannot of course 
 be relied on for this purpose, since both consciousness and volition 
 are abolished at the time of death. The activity of the glandular 
 organs, owing to the stoppage of the circulation, disappears also 
 very rapidly, or at least cannot readily be demonstrated. The 
 
AND ITS MODE OF ACTION. 
 
 331 
 
 Fig. 133. 
 
 M 
 
 contractility of the muscles, however, lasts, as we have seen, for a 
 considerable time after death, and may accordingly be employed 
 with great readiness as a test of nervous irritability. The manner 
 of its employment is as follows: — 
 
 The leg of a frog is separated from the body and stripped of its 
 integument; the sciatic nerve having been previously dissected 
 out and cut off at its point of emergence from the 
 spinal canal, so that a considerable portion of it 
 remains in connection with the separated limb. 
 (Fig, 133.) If the two poles of a galvanic appa- 
 ratus be now placed in contact with different 
 points (a b) of the exposed nerve, and a discharge 
 allowed to pass between them, at the moment 
 of discharge a sudden contraction takes place in 
 the muscles below. It will be seen that this ex- 
 periment is altogether different from the one re- 
 presented in Fig. 182. In that experiment the 
 galvanic discharge is passed througli the muscles 
 themselves, and acts upon them by direct stim- 
 ulus. Here, however, the discharge passes only 
 from a to & through the tissues of the nerve, and 
 acts directly upon the nerve alone ; while the 
 nerve, acting upon the muscles by its own pecu- 
 liar agency, causes in this way a muscular con- 
 traction. It is evident that in order to produce 
 this effect, two conditions are equally essential: 1st. 
 The irritability of the muscles ; and 2d. The irri- 
 tability of the nerves. So long, therefore, as the 
 muscles are in a healthy condition, their contraction, under the 
 influence of a stimulus applied to the nerve, demonstrates the 
 irritability of the latter, and may be used as a convenient measure 
 of its intensity. 
 
 The irritdbility of the nerve continues after death. The knowledge 
 of this fact follows from what has just been said with regard to ex- 
 perimenting upon the frog's leg, prepared as above. The irrita- 
 bility of the nerve, like that of the muscle, depends directly upon 
 its anatomical structure and constitution ; and so long as these re- 
 main unimpaired, the nerve will retain its vital properties, though 
 respiration and circulation may have ceased. For the same reason, 
 also, as that given above with regard to the muscles, nervous irri- 
 tability lasts much longer after death in the cold-blooded than in 
 
 Fror' s Leg, with 
 sciatic nerve (N) at- 
 tached. — a b. Poles of 
 galvanic battery, ap- 
 plied to nerve. 
 
332 OF NERVOUS IRRITABILITY 
 
 the warm-blooded animals. Various artificial irritants may be em- 
 ployed to call it into activity. Pinching or pricking the exposed 
 nerve with steel instruments, the application of caustic liquids, and 
 the passage of galvanic discharges, all have this effect. The electric 
 current, however, is much the best means to employ for this pur- 
 pose, since it is more delicate in its operation than the others, and 
 will continue to succeed for a longer time. 
 
 The nerve is, indeed, so exceedingly sensitive to the electric cur- 
 rent, that it will respond to it when insensible to all other kinds of 
 stimulus. A frog's leg freshly prepared with the nerve attached, 
 as in Fig. 133, will react so readily whenever a discharge is passed 
 through the nerve, that it forms an extremely delicate instrument 
 for detecting the presence of electric currents of low intensity, and 
 has even been used for this purpose by Matteucci, under the name 
 of the " galvanoscopic frog." It is only necessary to introduce the 
 nerve as part of the electric circuit; and if even a very feeble cur- 
 rent be present, it is at once betrayed by a muscular contraction. 
 
 The superiority of electricity over other means of exciting nerv- 
 ous action, such as mechanical violence or chemical agents, pro- 
 bably depends upon the fact that the latter necessarily alter and 
 disintegrate more or -less the substance of the nerve, so that its 
 irritability soon disappears. The electric current, on the other 
 hand, excites the nervous irritability without any marked injury to 
 the substance of the nervous fibre. Its action may, therefore, be 
 continued for a longer period. 
 
 Nervous irritability^ like that of the muscles, is exhausted by repeated 
 excitement. If a frog's leg be prepared as above, with the sciatic 
 nerve attached, and allowed to remain at rest in a damp and cool 
 place, where its tissue will not become altered by desiccation, the 
 nerve will remain irritable for many hours ; but if it be excited, 
 soon after its separation from the body, by repeated galvanic shocks, 
 it soon begins to react with diminished energy, and becomes gra- 
 dually less and less irritable, until it at last ceases to exhibit any 
 further excitability. If it be now allowed to remain for a time at 
 rest, its irritability will be partially restored ; and muscular con- 
 tractions will again ensue on the application of a stimulus to the 
 nerve. Exhausted a second time, and a second time allowed to re- 
 pose, it will again recover itself; and this maybe even repeated 
 several times in succession. At each repetition, however, the re- 
 covery of nervous irritability is less complete, until it finally dis- 
 appears altogether, and can no longer be recalled. 
 
AND ITS MODE OF ACTION. 383 
 
 Yarious accidental circumstances tend to diminisTi or destroy 
 nervous irritability. The action of the woorara poison, for example, 
 destroys at once the irritabilit}'- of the nerves; so that in animals 
 killed by this substance, no muscular contraction takes place on 
 irritatinor the nervous trunk. Severe and sudden mechanical in- 
 juries often have the same effect; as where death is produced by 
 violent and extensive crushing or laceration of the body or limbs. 
 Such an injury produces a general disturbance, or shock as it is 
 called, which affects the entire nervous system, and destroys or 
 suspends its irritability. The effects of such a nervous shock may 
 frequently be seen in the human subject after railroad accidents, 
 where the patient, though very extensively injured, may remain 
 for some hours without feeling the pain of his wounds. It is only 
 after reaction has taken place, and the activity of the nerves has 
 been restored, that the patient begins to be sensible of pain. 
 
 It will often be found, on preparing the frog's leg for experiment 
 as above, that immediately after the limb has been separated from 
 the body and the integument removed, the nerve is destitute of 
 irritability. Its vitality has been suspended by the violence in- 
 flicted in the preparatory operation. In a few moments, however, 
 if kept under favorable conditions, it recovers from the shock, and 
 regains its natural irritability. 
 
 The action. of the galvanic current upon the nerve, as first shown 
 by the experiments of Matteucci, is in many respects peculiar. If 
 the current be made to traverse the nerve in the natural direction 
 of its fibres, viz., from its origin toward its distribution, as from a 
 to b in Fig. 138, it is called the direct current. If it be made to 
 pass in the contrary direction, as from b to a, it is called the inverse 
 current. When the nerve is fresh and exceedingly irritable, a 
 muscular contraction takes place at both the commencement and 
 termination of the current, whether it be direct or inverse. But 
 very soon afterward, when the activity of the nerve has become 
 somewhat diminished, it will be found that contraction takes place 
 only at the commencement of the direct and at the termination of the 
 inverse current. This may readily be shown by preparing the two 
 legs of the same frog in such a manner that they remain connected 
 with each other by the sciatic nerves and that portion of the spinal 
 column from which these nerves take their origin. The two legs, 
 so prepared, should be placed each in a vessel of water, with the 
 nervous connection hanging between (Fig. 184). If the positive 
 pole, a, of the battery be now placed in the vessel which holds leg 
 
334 
 
 OF NERVOUS IRRITABILITY 
 
 No. 1, and the negative pole, J, in that containing leg No. 2, it will 
 be seen that the galvanic current will traverse the two legs in op- 
 posite directions. In No. 1 it will pass in a direction contrary to 
 the course of its nervous fibres, that is, it will be for this leg an 
 
 Fig. 134. 
 
 inverse current; while in No. 2 it will pass in the same direction 
 with that of the nervous fibres, that is, it will be for this leg a direct 
 current. It will now be found that at the moment when the cir- 
 cuit is completed, a contraction takes place in No. 2 by the direct 
 current, while No. 1 remains at rest ; but at the time the circuit is 
 broken, a contraction is produced in No. 1 by the inverse current, 
 but no movement takes place in No. 2. A succession of alternate 
 contractions may thus be produced in the two legs by repeatedly 
 closing and opening the circuit. If the position of the poles, a, i, 
 be reversed, the effects of the current will be changed in a corres- 
 ponding manner. 
 
 After a nerve has become exhausted by the direct current, it is 
 still sensitive to the inverse; and after exhaustion by the inverse, 
 it is still sensitive to the direct. It has even been found by Mat- 
 teucci that after a nerve has been exhausted for the time by the direct 
 current, the return of its irritability is hastened by the subsequent 
 passage of the inverse current; so that it will become again sensi- 
 tive to the direct current sooner than if allowed to remain at rest. 
 Nothing, accordingly, is so exciting to a nerve as the passage of 
 direct and inverse currents, alternating with each other in rapid 
 succession. Such a mode of applying the electric stimulus is that 
 usually adopted in the galvanic machines used in medical practice, 
 for the treatment of certain paralytic affections. In these machines, 
 
AND ITS MODE OF ACTION. 335 
 
 tbe electric current is alternately formed and broken witli great 
 rapidity, thus producing the greatest effect upon the nerves with 
 the smallest expenditure of electricity. Such alternating currents, 
 however, if very powerful, exhaust the nervous irritability more 
 rapidly and completely than any other kind of irritation ; and in 
 an animal killed by the action of a battery used in this manner, the 
 nerves may be found to be entirely destitute of irritability from the 
 moment of death. 
 
 The irrilabiUty of the nerves is distinct from that of the muscles; and 
 the two may be destroyed or suspended independently of each other. 
 When the frog's leg has been prepared and separated from the 
 body, with the sciatic nerve attached, the muscles contract, as we 
 have seen, whenever the nerve is irritated. The irritability of the 
 nerve, therefore, is manifested in this instance only through that of 
 the muscle, and that of the muscle is called into action only through 
 that of the nerve. The two properties may be separated from each 
 other, however, by the action of tcoorara, which has the power, as 
 first pointed out by Bernard, of destroying the irritability of the 
 nerve without affecting that of the muscles. If a frog be poisoned 
 by this substance, and the leg prepared as above, the poles of a 
 galvanic battery applied to the nerve will produce no effect ; show- 
 ing that the nervous irritability has ceased to exist. But if the 
 galvanic discharge be passed directly through the muscles, contrac- 
 tion at once takes place. The muscular irritability has survived 
 that of the nerves, and must therefore be regarded as essentiallv 
 distinct from it. 
 
 It will be recollected, on the other hand, that in cases of death 
 from the action of sulphocyanide of potassium, the muscular irri- 
 tability is itself destroyed ; so that no contractions occur, even when 
 the galvanic discharge is made to traverse the muscular tissue. 
 
 There are, therefore, two kinds of paralysis : first, a muscular 
 paralysis, in which the muscular fibres themselves are directly 
 affected ; and second, a nervous paralysis, in which the affection is 
 confined to the nervous filaments, the muscles retaining their natural 
 properties, and being still capable of contracting under the influence 
 of a direct stimulus. 
 
 Nature of the Nervous Force. — It will readily be seen that the 
 nervous force, or the agency by which the nerve acts upon a muscle 
 and causes its contraction, is entirely a peculiar one, and cannot be 
 regarded as either chemical or mechanical in its nature. The force 
 which is exerted by a nerve in a state of activity is not directly 
 
336 OF NERVOUS IRRITABILITY 
 
 appreciable in any way by the senses, and can be judged of only 
 by its efifect in causing muscular contraction. This peculiar vitality 
 of the nerve, or, as it is sometimes called, the " nervous force," does 
 not precisely resemble in its operation any of the known physical 
 forces. It has, however, a partial resemblance in some respects to 
 electricity; and this has been sufficient to lead some writers into the 
 error of regarding the two as identical, and of supposing electricity 
 to be really the force acting in the nerves, and operating through 
 them upon the muscles. The principal points of resemblance 
 existing between the two forces, and which have been used in 
 support of the above opinion, are the following : — 
 
 1st. The identity of their effects upon the muscular fibre. 
 2d. The rapidity and peculiarity of their action, by which the 
 force is transmitted almost instantaneously to a distant point, with- 
 out producing any visible effect on the intervening parts. 
 
 3d. The extreme sensibility of nerves to the electric current; and 
 4th. The phenomena of electrical fishes. 
 
 As these considerations are of some importance in settling the 
 question which now occupies us, we shall examine them in succes- 
 sion. 
 
 1st. The Identity of their Effects upon the Muscular Fibre. — It is 
 very true that the muscular fibre contracts under the influence of 
 electricity, as it does under that of the nervous force. This fact, 
 however, does not show the identity of the two forces, but only 
 that they are both capable of producing one particular phenomenon; 
 or that electricity may replace or imitate the nervous force in its 
 action on the muscles. But there are various other agents, as we 
 have already seen, both mechanical and chemical, which will pro- 
 duce the same effect, when applied to the muscular tissue. Elec- 
 tricity, therefore, is only one among several physical forces which 
 resemble each other in this respect, but which are not on that 
 account to be regarded as identical. 
 
 2d. The Rapidity and Peculiarity of their Action^ by which the 
 force is transmitted almost instantaneously to a distant pointy without 
 producing any visible effect on the intervening parts, — This is a very 
 remarkable and important character, both of the nervous force and 
 of electricity. In neither case is there any visible effect produced 
 on the nervous or metallic fibre which acts as a conducting medium ; 
 but the final action is exerted upon the substances or organs with 
 which it is in connection. No definite conclusion, however, can 
 be properly derived from the rapidity of their transmission, since 
 
AND ITS MODE OF ACTION. 337 
 
 this rapidity has never been accurately measured in either instance. 
 We know that light and sound both travel with much greater 
 rapidity than most other physical forces, and that electricity is more 
 rapid in its transmission than either ; but there is no evidence that 
 the velocity of the latter and that of the nervous force are the same. 
 We can only say that in both instances the velocity is very great, 
 without being able to compare them together with any degree of 
 accuracy. The mode of transmission, moreover, alluded to above, 
 is not peculiar to the two forces which are supposed to be identical. 
 Light, for example, is transmitted like them through conducting 
 media, without producing in its passage any sensible effect until it 
 meets with a body capable of reflecting it. In the interval, there- 
 fore, between the luminous body and the reflecting one, there is 
 the same apparent want of action as in the nerve, between the point 
 at which the irritation is applied and its termination in the mus- 
 cular tissue. 
 
 3d. The extreme Sensibility of Nerves to the Electric Current. — It 
 has already been mentioned that the electric current is the most 
 delicate of all the means of irritation that may be applied to the 
 nerve after death ; and that it may be used with less deleterious 
 effect than any other. The evident reason for this, however, has 
 already been given. Electricity is one among several physical 
 agents by which the nerve may be artificially excited after death. 
 It is less destructive to the nervous texture than any other, and 
 consequently exhausts its vitality less rapidly. All these agents 
 vary in the delicacy of their operation; and though the electric 
 current happens to be the most efficient of all, it is still simply an 
 artificial irritant, like the rest, capable of imitating, in its own way, 
 the natural stimulus of the nerve. 
 
 4th. The Phenomena of Electrical Fishes. — It has been fully demon- 
 strated that certain fish (gymnotus and torpedo) have the power of 
 generating electricity, and of producing electric discharges, which 
 are often sufficiently powerful to kill small animals that may come 
 within their reach. That the force generated by these animals is 
 in reality electricity, is beyond a doubt. It is conducted by the 
 same bodies which serve as conductors for electricity, and is stopped 
 by those which are non-conductors of the same. All the ordinary 
 phenomena produced by the electric current, viz : the heating and 
 melting of a fine conducting wire, the induction of secondary 
 currents and of magnetism, the decomposition of saline solutions, 
 and even the electric spark, have all been produced by the force 
 22 
 
33S OF NERVOUS IRRITABILITY 
 
 generated by these animals. There is accordingly, no room for 
 doubt as to its nature. 
 
 This fact, however, is very far from demonstrating the electric 
 character of the nervous force in general. It is, on the contrary, 
 directly opposed to such a supposition ; since the gymnotus and 
 torpedo are capable of generating electricity simply because they 
 have a special organ destined for this purpose. This organ, which is 
 termed the " electrical organ," is peculiar to these fish, and where 
 it is absent, the power of generating electricity is absent also. The 
 electrical organs of the gymnotus and torpedo occupy a considerable 
 portion of the body, and are largely supplied with nerves which 
 regulate their function. If these nerves be divided, tied, or injured 
 in any way, the electrical organ is weakened or paralyzed, just as 
 the muscles would be if the nerves distributed to them were sub- 
 jected to a similar violence. The electricity produced by these 
 animals is not supplied by the nerves, but by a special generating 
 organ, the action of which is regulated by nervous influence. 
 
 The reasons quoted above, therefore, are quite insufficient for 
 establishing any relation of identity between the nervous force and 
 electricity. There are, moreover, certain well authenticated facts 
 directly opposed to such a supposition, the most important of which 
 are the following : — 
 
 The first is, that no electrical current has been actually found to exist 
 in an irritated nerve. The most conclusive experiments on this point 
 are those which were made by Longet and Matteucci, in company 
 with each other, at the veterinary school of Alfort.^ The galvano- 
 meter employed in these investigations was constructed under the 
 personal direction of the experimenters, and was of extreme delicacy. 
 The oscillating needle was surrounded by 2500 turns of conducting 
 wire, and the poles were each armed with a platinum plate, having 
 an exposed surface of one sixth of a square inch. When the poles 
 of the apparatus had been repeatedly immersed in spring water, so 
 that no further variation was produced from this source, the instru- 
 ment was considered as ready for use. The sciatic nerve of a liv- 
 ing horse was then exposed, and the poles of the galvanometer 
 placed in contact with it, in various positions, both diagonally and 
 longitudinally, and at various depths in its interior. The examina- 
 tion was continued for a quarter of an hour, during which time the 
 painful sensations of the animal were testified by constant strug- 
 gling movements of the limbs; showing that both the motor and 
 
 ' Longet, Traite de Physiologic. Paris, 1850, vol ii. p. 130. 
 
AND ITS MODE OF ACTION. 339 
 
 sensitive filaments of the nerve were in a high state of activity. 
 The conclusion, however, to which the experimenters were con- 
 ducted was the following, viz: that "there was no constant and re- 
 liable evidence of the existence of an electric current in the nerve." 
 
 Secondly. The mode of conduction of the nervous force is different 
 from that of electricity/. The latter force, in order to exert its charac- 
 teristic effects, must be transmitted through isolated conductors, so 
 arranged as to form a complete circuit. No such circuit has ever 
 been shown to exist in the nervous system ; and the nerves them- 
 selves, the only tissues capable of conducting the nervous force, are 
 not particularly good conductors of electricity; no better, for exam- 
 ple, than the muscles or the areolar tissue. We know of nothing, 
 therefore, which should prevent an electric current, passing through 
 a nerve, from being dispersed and lost among the adjacent tissues. 
 This is not the case, however, with the natural stimulus conveyed 
 by the nervous filament. 
 
 Moreover the nerve, in order to conduct its own peculiar force, 
 must be in a state of complete integrity. If a ligature be applied 
 to it, or if it be pinched or lacerated, the muscles to which it is dis- 
 tributed are paralyzed for all voluntary motion, and yet it transmits 
 the electric current as readily as before. If the nerve be divided, 
 and its divided extremities replaced in apposition with each other, 
 it will still act perfectly well as a conductor of electricity, though 
 it is needless to say that its natural function is at once destroyed. 
 The difference in the mode of conduction between the two forces 
 may be shown in a still more striking manner, as follows. Let the 
 nerve connected with a frog's leg be divided, and its two extremi- 
 ties joined to each other by a piece of moist cotton thread. If the 
 galvanic current be now passed through the detached portion of the 
 nerve, no contraction will take place ; because the nervous force, 
 excited in the detached portion, cannot be transmitted through the 
 cotton thread to the remainder. But if one of the galvanic poles 
 be applied above, and the other below the point of division, a con- 
 traction is immediately produced ; since the electric current is 
 readily transmitted by the cotton thread, and excites the lower 
 portion of the nerve, which is still in connection with the muscles. 
 
 The nervous force, therefore, while it has some points of resem- 
 blance with electricity, presents also certain features of dissimilarity 
 which are equally important. It must be regarded accordingly as 
 distinct in its nature from other known physical forces, and as 
 altogether peculiar to the nervous tissue in which it originates. 
 
840 THE SPINAL CORD. 
 
 CHAPTER III. 
 
 THE SPINAL CORD. 
 
 We have already seen that the spinal cord is a long ganglion, 
 covered with longitudinal bundles of nervous filaments, and occu- 
 pying the cavity of the spinal canal. It sends out nerves which 
 supply the muscles and integument of at least nine-tenths of the 
 whole body, viz., those of the neck, trunk, and extremities. All 
 these parts of the body are endowed with two very remarkable 
 properties, the exercise of which depends, directly or indirectly, 
 upon the integrity and activity of the spinal cord, viz., the power 
 of sensation and the power of motion. Both these properties are 
 said to reside in the nervous system, because they are so readily 
 influenced by its condition, and are so closely connected with its 
 physiological action. "We shall therefore commence the study of 
 the spinal cord with an examination of these two functions, and of 
 the situation which they occupy in the nervous system. 
 
 / 
 
 DISTINCT SEAT OF SENSATION AND MOTION IN THE NERVOUS SYSTEM. 
 
 Sensation and motion are usually the first functions which suffer 
 by any injury inflicted on the nervous system. As a general rule, 
 they are both suspended or impaired at the same time, and in a 
 nearly equal degree. In a fainting fit, an attack of apoplexy, con- 
 cussion or compression of the brain or spinal cord, or a wound of 
 any kind involving the nerves or nervous centres, insensibility and 
 loss of motion usually appear simultaneously. It is difficult, there- 
 fore, under ordinary conditions, to trace out the separate action of 
 these two functions, or to ascertain the precise situation occupied 
 by each. 
 
 This difficulty, however, may be removed by examining sepa- 
 rately different parts of the nervous system. In the instances 
 mentioned above, the injury which is inflicted is comparatively an 
 
DISTINCT SEAT OF SENSATION AND MOTION. 341 
 
 extensive one, and involves at the same tinne many adjacent parts. 
 T5ut instances sometimes occur in which the two functions, sensa- 
 tion and motion, are affected independently of each other, owing to 
 the peculiar character and situation of the injury inflicted. Sensa- 
 tion may be impaired without loss of motion, and loss of motion 
 may occur without injury to sensation. In tic douloureux, for 
 example, we have an exceedingly painful affection of the sensitive 
 parts of the face, without any impairment of its power of motion • 
 and in facial paralysis we often see a complete loss of motion affect- 
 ing one side of the face, while the sensibility of the part remains 
 altogether unimpaired. 
 
 The above facts first gave rise to the belief that sensation and 
 motion might occupy distinct parts of the nervous system ; since it 
 would otherwise be difficult to understand how the two could be 
 affected independently of each other by anatomical lesions. It has 
 accordingly been fully established, by the labors of Sir Charles Bell, 
 Miiller, Panizza, and Longet, that the two functions do in reality 
 occupy distinct parts of the nervous system. 
 
 If any one of the spinal nerves, in the living animal, after being 
 exposed at any part of its course outside the spinal canal, be divided, 
 ligatured, bruised, or otherwise seriously injured, paralysis of motion 
 and loss of sensation are immediately produced in that part of the 
 body to which the nerve is distributed. If, on the other hand, the 
 same nerve be pricked, galvanized, or otherwise gently irritated, a 
 painful sensation and convulsive movements are produced in the 
 same parts. The nerve is therefore said to be both sensitive and 
 excitable; sensitive, because irritation of its fibres produces a pain- 
 ful sensation, and excitable, because the same irritation causes mus- 
 cular contraction in the parts below. 
 
 The result of the experiment, however, will be different if it be 
 tried upon the parts situated inside the spinal canal, and particularly 
 upon the anterior and posterior roots of the spinal nerves. If an 
 irritation be applied, for example, to the anterior root of a spinal 
 nerve, in the living animal, convulsive movements are produced in 
 the parts below, but there is no painful sensation. The anterior 
 root accordingly is said to be excitable, but not sensitive. If the 
 posterior root, on the other hand, be irritated, acute pain is pro- 
 duced, but no convulsive movements. The posterior root is there- 
 fore sensitive, but not excitable. A similar result is obtained by a 
 complete division of the two roots. Division of the anterior root 
 produces paralysis of motion, but no insensibility ; division of the 
 
3ri2 THE SPINAL CORD. 
 
 posterior root produces complete loss of sensibility, but no muscular 
 paralysis. 
 
 We have here, then, a separate localization of sensation and 
 motion in the nervous system ; and it is accordingly easy to under- 
 stand how one may be impaired without injury to the other, or 
 how both may be simultaneously affected, according to the situation 
 and extent of the anatomical lesion. 
 
 The two roots of a spinal nerve differ from each other, further- 
 more, in their mode of transmitting the nervous impulse. If the 
 posterior root be divided (E'ig. 135) at «, b, and an irritation applied 
 
 Fig. 135. 
 
 Diagi-am of SpiXAL Cord and Nekves. The posterior root is seeu divided at n, h. tlie 
 anterior at c, d. 
 
 to the separated extremity (a), no effect will be produced ; but if 
 the irritation be applied to the attached extremity {h\ a painful 
 sensation is immediately the result. The nervous force, therefore, 
 travels in the posterior root from without inward, but cannot pass 
 from within outward. If the anterior root, on the other hand, be 
 divided at c, d, and its attached extremity [d) irritated, no effect 
 follows ; but if the separated extremity (c) be irritated, convulsive 
 movements instantly take place. The nervous force, consequently, 
 travels in the anterior root from within outward, but cannot pass 
 from without inward. 
 
 The same thing is true with regard to the transmission of sensa- 
 tion and motion in the spinal nerves outside the spinal canal. If 
 one of these nerves be divided in the living animal, and its attached 
 extremity irritated, pain is produced, but no convulsive motion; if 
 
SENSIBILITY AND EXCITABILITY IN SPINAL CORD. 343 
 
 the irritation be applied to its separated extremity, muscular con- 
 tractions follow, but no painful sensation. 
 
 There are, therefore, two kinds of filaments in the spinal nerves, 
 not distinguishable by the eye, but entirely distinct in their character 
 and function, viz., the "sensitive" filaments, or those which convey 
 sensation, and the " motor" filaments, or those which excite move- 
 ment. These filaments are never confounded with each other in 
 their action, nor can they perform each other's functions. The sen- 
 sitive filaments convey the nervous force only in a centripetal, the 
 motor only in a centrifugal direction, The former preside over 
 sensation, and have nothing to do with motion ; the latter preside 
 over motion, and have nothing to do with sensation. Within the 
 spinal canal the two kinds of filaments are separated from each 
 other, constituting the anterior and posterior roots of each spinal 
 nerve; but externally they are mingled together in a common 
 trunk. While the anterior and posterior roots, therefore, are ex- 
 clusively sensitive or exclusively motor, the spinal nerves beyond 
 the junction of the roots are called mixed nerves^ because they con- 
 tain at the same time motor and sensitive filaments. The mixed 
 nerves accordingly preside at the same time over the functions of 
 movement and of sensation. 
 
 DISTINCT SEAT OF SENSIBILITY AND EXCITABILITY IN THE SPINAL 
 
 CORD. 
 
 Various experimenters have demonstrated the fact that different 
 ])arts of the spinal cord, like the two roots of the spinal nerves, are 
 separately endowed with sensibility and excitability. The anterior 
 columns of the cord, like the anterior roots of the spinal nerves, 
 are excitable but not sensitive ; the posterior columns, like the 
 posterior roots of the spinal nerves, are sensitive but not excitable. 
 Accordingly, when the spinal canal is opened in the living animal, 
 an irritation applied to the anterior columns of the cord produces 
 immediately convulsions in the limbs below ; but there is no indi- 
 cation of pain. On the other hand, signs of acute pain become 
 manifest whenever the irritation is applied to the posterior column ; 
 but no muscular contractions follow, other than those of a voluntary 
 character. Longet has found'that if the spinal cord be exposed in 
 the lumbar region and completely divided at that part by trans- 
 
 ' Traite de Physiologie, voL ii. part 2, p. 8. 
 
344 THE SPINAL COED. 
 
 verse section, the application of any irritant to tbe anterior surface 
 of the separated portion produces at once convulsions below ; while 
 if applied to the posterior columns behind the point of division, it 
 has no sensible effect whatever. The anterior and posterior columns 
 of the cord are accordingly, so far, analogous in their properties to 
 the anterior and posterior roots of the spinal nerves, and are plainly 
 composed, to a greater or less extent, of a continuation of their 
 filaments. 
 
 These filaments, derived from the anterior and posterior roots 
 of the spinal nerves, pass upward through the spinal cord toward 
 the brain. An irritation applied to any part of the integument 
 is then conveyed, along the sensitive filaments of the nerve and 
 its posterior root, to the spinal cord; then upward, along the 
 longitudinal fibres of the cord to the brain, where it produces a 
 sensation corresponding in character with the original irritation. 
 A motor impulse, on the other hand, originating in the brain, is 
 transmitted downward, along the longitudinal fibres of the cord, 
 passes outward by the anterior root of the spinal nerve, and follow- 
 ing the motor filaments of the nerve through its trunk and branches, 
 produces at last a muscular contraction at the point of its final 
 distribution. 
 
 CEOSSED ACTION OF THE SPINAL COED. 
 
 As the anterior columns of the cord pass upward to join the 
 medulla oblongata, a decussation takes place between them, as we 
 have already mentioned in Chapter I. The fibres of the right 
 anterior column pass over to the left side of the medulla oblongata, 
 and so upward to the left side of the brain ; while the fibres of the 
 left anterior column pass over to the right side of the medulla 
 oblongata, and so upward to the right side of the brain. This 
 decussation may be readily shown (as in Fig. 130) by gently 
 separating the anterior columns from each other, at the lower ex- 
 tremity of the medulla oblongata, where the decussating bundles 
 may be seen crossing obliquely from side to side, at the bottom of 
 the anterior median fissure. Below this point, the anterior columns 
 remain distinct from each other on each side, and do not communi- 
 cate by any further decussation. 
 
 If the anterior columns of the spinal cord, therefore, be wounded 
 at any point in the cervical, dorsal, or lumbar region, a paralysis 
 
CROSSED ACTION OF THE SPINAL CORD. 345 
 
 of voluntary motion is produced in the limbs below, on the same 
 side with the injury. But if a similar lesion occur in the brain, 
 the paralysis which results is on the opposite side of the body. 
 Thus it has long been known that an abscess or an apoplectic 
 hemorrhage on the right side of the brain will produce paralysis 
 of the left side of the body; and injury of the left side of the 
 brain will be followed by paralysis of the right side of the body. 
 
 The spinal cord has also a crossed action in transmitting sensi- 
 tive as well as motor impulses. It has been recently demonstrated 
 by Dr. Brown-Sdquard,' that the crossing of the sensitive fibres in 
 the spinal cord does not take place, like that of the motor fibres, 
 at its upper portion only, but throughout its entire length ; so that 
 the sensitive fibres of the right spinal nerves, very soon after their 
 entrance into the cord, pass over to the left side, and those of the 
 left spinal nerves pass over to the right side. For if one lateral 
 half of the spinal cord of a dog be divided in the dorsal region, 
 the power of sensation remains upon the corresponding side of the 
 body, but is lost upon the opposite side. It has been shown, fur- 
 thermore, by the same observer,^ that the sensitive fibres of the 
 spinal nerves, when they first enter the cord join the posterior 
 columns, which are everywhere extremely sensitive ; but that they 
 very soon leave the posterior columns, and, passing through the 
 central parts of the cord, run upward to the opposite side of the 
 brain. If the posterior columns, accordingly, be alone divided at 
 any part of the spinal cord, sensibility is not destroyed in all the 
 nerves behind the seat of injury, but only in those which enter the 
 cord at the point of section ; since the posterior columns consist 
 of different nervous filaments, joining them constantly on one side 
 from below, and leaving them on the other to pass upward toward 
 the brain. """"^ 
 
 The spinal cord has therefore a crossed action, both for sensa- 
 tion and motion ; but the crossing of the motor filaments occurs 
 only at the medulla oblongata, while that of the sensitive filaments 
 takes place throughout the entire length of the cord itself. 
 
 There are certain important facts which still remain to be noticed, 
 regarding the mode of action of the spinal cord and its nerves. 
 They are as follows : — 
 
 ' Experimental Researches applied to Physiology and Pathology. New York, 
 1853. 
 
 2 Memoirs sur la Physiologie de la Moelle epiniere ; Gazette Medicale de Paris, 
 1855. 
 
3.46 THE SPINAL CORD. 
 
 1. An {rrilation a2'>plied to a spinal nerve at the middle of its course 
 "produces the same effect as if it traversed its entire length. Thus, if the 
 sciatic or median nerve be irritated at any part of its course, con- 
 traction is produced in the muscles to which these nerves are dis- 
 tributed, just as if the impulse had originated as usual from the 
 brain. This fact depends upon the character of the nervous fila- 
 ments, as simple conductors. Wherever the impulse may originate, 
 the final effect is manifested only at the termination of the nerve. 
 As the impulse in the motor nerves travels always in an outward 
 direction, the effect is always produced at the muscular termination 
 of the filaments, no matter how small or how large a portion of 
 their length may have been engaged in transmitting the stimulus. 
 
 If the irritation, again, be applied to a sensitive nerve in the 
 middle of its course, the painful sensation is felt, not at the point 
 of the nerve directly irritated, but in that portion of the integu- 
 ment to which its filaments are distributed. Thus, if the ulnar 
 nerve be accidentally struck at the point where it lies behind the 
 inner condyle of the humerus, a sensation of tingling and numb- 
 ness is produced in the last two fingers of the corresponding hand. 
 It is common to hear patients who have suffered amputation com- 
 plain of painful sensations in the amputated limb, for weeks or 
 months, and sometimes even for years after the operation. They 
 assert that they can feel the separated parts as distinctly as if they 
 were still attached to the body. This sensation, which is a real 
 one and not fictitious, is owing to some irritation operating upon 
 the divided extremities of the nerves in the cicatrized wound. Such 
 an irritation, conveyed to the brain by the sensitive fibres, will pro- 
 duce precisely the same sensation as if the amputated parts were 
 still present, and the irritation actually applied to them. 
 
 It is on this account also that division of the trifacial nerve is 
 not always effectual in the cure of tic douloureux. If the cause of 
 the difficulty be seated upon the trunk of the nerve, between its 
 point of emergence from the bones and its origin in the brain, it is 
 evident that division of the nerve upon the face will be of no 
 avail; since the cause of irritation will still exist behind the point 
 of section, and the same painful sensations will still be produced in 
 the brain. 
 
 2. The irritability of the motor filaments disapjyears from within oiit- 
 ward, that of the sensitive filaments from without inward. Immedi- 
 ately after the separation of the frog's leg from the body, irritation 
 of the nerve at any point produces muscular contraction in the 
 
INDEPENDENCE OF NEEVOUS FILAMENTS. 347 
 
 limb below. As time elapses, however, and the irritability of the 
 nerve diminishes, the galvanic current, in order to produce con- 
 traction, must be applied at a point nearer its termination. Subse- 
 quently, the irritability of the nerve is entirely lost in its upper 
 portions, but is retained in the parts situated lower down, from 
 which it also, in turn, afterward disappears; receding in this man- 
 ner farther and farther toward the terminal distribution of the 
 nerve, where it finally disappears altogether. 
 
 On the other hand, sensibility disappears, at the time of death, 
 first in the extremities. From them the numbness gradually creeps 
 upward, invading successively the middle and upper portions of the 
 limbs, and the more distant portions of the trunk. The central 
 parts are the last to become insensible. 
 
 3. Each nervous filament acts independently of the rest throughout its 
 entire lengthy and does not communicate its irritation to those which are 
 in proximity with it. It is evident that this is true with regard to 
 the nerves of sensation, from the fact that if the integument be 
 touched with the point of a needle, the sensation is referred to that 
 spot alone. Since the nervous filaments coming from it and the 
 adjacent parts are all bound together in parallel bundles, to form 
 the trunk of the nerve, if any irritation were communicated from 
 one sensitive filament to another, the sensation produced would be 
 indefinite and diffused, whereas it is really confined to the spot irri- 
 tated. If a frog's leg, furthermore, be prepared, with the sciatic 
 nerve attached, a few of the fibres separated laterally from the 
 nervous trunk for a portion of its length, and the poles of a galvanic 
 battery applied to the separated portion, the contractions which 
 follow in the leg will not be general, but will be confined to those 
 muscles in which the galvanized nervous fibres especially have 
 their distribution. There are also various instances, in the body, 
 of antagonistic muscles, which must act independently of each 
 other, but which are supplied with nerves from a common trunk. 
 The superior and inferior straight muscles of the eyeball, for 
 example, are both supplied by the motor oculi communis nerve. 
 Extensor and flexor muscles, as, for example, those of the fingers, 
 are often supplied by the same nerve, and yet act alternately with- 
 out mutual interference. It is easy to see that if this were not the 
 case, confusion would constantly arise, both in the perception of 
 sensations, and in the execution of movements, 
 
 4. There are certain sensations which are excited simultaneously 
 by the same causes, and which are termed associated sensations ; and 
 
348 THE SPINAL COED. 
 
 there are also certain movements which take place simultaneously, 
 and are called associated movements. In the former instance, one of 
 the associated sensations is called up immediately upon the percep- 
 tion of the other, without requiring any direct impulse of its own. 
 Thus, tickling the soles of the feet produces a peculiar sensation 
 at the epigastrium. Nausea is occasioned by certain disagreeable 
 odors, or by rapid rotation of the body, so that the landscape seems 
 to turn round. A striking example of associated movements, on 
 the other hand, may be found in the action of the muscles of the 
 eyeball. The eyeballs always accompany each other in their lateral 
 motions, turning to the right or the left side simultaneously. It is 
 evident, however, that in producing this correspondence of motion, 
 the left internal rectus muscle must contract and relax together 
 with the right external; while a similar harmony of action must 
 exist between the right internal and the left external. The explana- 
 tion of such singular correspondences cannot be found in the anato- 
 mical arrangement of the muscles themselves, nor in that of the 
 nervous filaments by which they are directly supplied, but must be 
 looked for in some special endowment of the nervous centres from 
 which they originate. 
 
 EEFLEX ACTION OF THE SPINAL CORD. 
 
 The spinal cord, as we have thus far examined it, may be re- 
 garded simply as a great nerve ; that is, as a bundle of motor and 
 sensitive filaments, connecting the muscles and integument below 
 with the brain above, and assisting, in this capacity, in the produc- 
 tion of conscious sensation and voluntary motion. Beside its nerv- 
 ous filaments, however, it contains also a large quantity of gray 
 matter, and is, therefore, itself a ganglionic centre, and capable of 
 independent action as such. We shall now proceed to study it in 
 its second capacity, as a distinct nervous centre. 
 
 If a frog be decapitated, and the body allowed to remain at rest 
 for a few moments, so as to recover from the depressing effects of 
 shock upon the nervous system, it will be found that, although sen- 
 sation and consciousness are destroyed, the power of motion still 
 remains. If the skin of one of the feet be irritated by pinching it 
 with a pair of forceps, the leg is immediately drawn up toward the 
 body, as if to escape the cause of irritation. If the irritation applied 
 to the foot be of slight intensity, the corresponding leg only will 
 
KEFLEX ACTION OF THE SPINAL CORD. 
 
 349 
 
 move; but if it be more severe in character, motions will often be 
 produced in the posterior extremity of the opposite side, and even 
 in the two fore-legs, at the same time. These motions, it is import- 
 ant to observe, are never spontaneous. The decapitated frog remains 
 perfectly quiescent if left to himself. It is only when some cause 
 of irritation is applied externally, that movements occur as above 
 described. 
 
 It will be seen that the character of these phenomena indicates 
 the active operation of some part of the nervous system, and par- 
 ticularly of some ganglionic centre. The irritation is applied to 
 the skin of the foot, and the muscles of the leg contract in conse- 
 quence; showing evidently the intermediate action of a nervous 
 connection between the two. 
 
 The effect in question is due to the activity of the spinal cord, 
 operating as a nervous centre. In order that the movements may 
 take place as above, it is essential that both the integument and the 
 muscles should be in communication with the spinal cord by nerv- 
 ous filaments, and that the cord itself be in a state of integrity. If 
 the sciatic nerve be divided in the upper part of the thigh, irrita- 
 tion of the skin below is no longer followed by any muscular con- 
 traction. If either the anterior or posterior roots of the nerve be 
 divided, the same want of action results; and finally, if, the nerve 
 and its roots remaining entire, the spinal cord itself be broken up 
 by a needle introduced into the spinal 
 canal, the integument may then be 
 irritated or mutilated to any extent, 
 without exciting the least muscular 
 contraction. It is evident, therefore, 
 that the spinal cord acts, in this case, 
 as a nervous centre, through which 
 the irritation applied to the skin is 
 communicated to the muscles. The 
 irritation first passes upward, as shown 
 in the accompanying diagram (Fig. 
 136), along the sensitive fibres of the 
 posterior root (a) to the gray matter 
 of the cord, and is then reflected back, 
 along the motor fibres of the anterior 
 root, until it finally reaches the mus- 
 cles, and produces a contraction. This action is known, accord 
 ingly, as the reflex action of the spinal cord. 
 
 Fig. 136. 
 
 Diagram of Spinal Cord in Ver- 
 tical Section, showing reflex action. 
 — a Posterior root of spinal nerve. 6. An- 
 terior root of spinal nerve. 
 
350 THE SPIXAL CORD. 
 
 It will be remembered that this reflex action of the cord is not 
 accompanied by any volition, nor even by any conscious sensation. 
 The function of the spinal cord as a nervous centre is simply to 
 convert an impression, received from the skin, into a motor impulse 
 which is sent out again to the muscles. There is absolutely no 
 farther action than this ; no exercise of will, consciousness, or judg- 
 ment. This action will therefore take place perfectly well after 
 the brain has been removed, and after the entire sympathetic sys- 
 tem has also been taken away, provided only that the spinal cord 
 and its nerves remain in a state of integrity. 
 
 The existence of this reflex action after death is accordingly an 
 evidence of the continued activity of the spinal cord, just as con- 
 tractility is an evidence of the activity of the muscles, and irrita- 
 bility of that of the nerves. Like the two last-mentioned properties, 
 also, it continues for a longer time after death in cold-blooded than 
 in warm-blooded animals. It is for this reason that frogs and other 
 reptiles are the most useful subjects for the study of these pheno- 
 mena, as for that of most others belonging to the nervous system. 
 
 The irritability of the spinal cord, as manifested by its reflex 
 action, may be very much exaggerated by certain diseases, and by 
 the operation of poisonous substances. Tetanus and poisoning b}^ 
 strychnine both act in this way, by heightening the irritability of 
 the spinal cord, and causing it to produce convulsive movements 
 on the application of external stimulus. It has been observed that 
 the convulsions in tetanus are rarely, if ever, spontaneous, but that 
 they always require to be excited by some external cause, such as 
 the accidental movement of the bedclothes, the shutting of a door, 
 or the sudden passage of a current of air. Such slight causes of 
 irritation, which would be entirely inadequate to excite involuntary 
 movements in the healthy condition, act upon the spinal cord, when 
 its irritability is heightened by disease, in such a manner as to pro- 
 duce violent convulsions. 
 
 Similar appearances are to be seen in animals poisoned by strych- 
 nine. This substance acts upon the spinal cord and increases its 
 irritability, without materially affecting the functions of the brain. 
 Its effects will show themselves, consequently, without essential 
 modification, after the head has been removed. If a decapitated 
 frocr be poisoned with a moderate dose of strychnine, the body and 
 limbs will remain quiescent so long as there is no external source 
 of excitement; but the limbs are at once thrown into convulsions 
 by the slightest irritation applied to the skin, as, for example, the 
 
KEFLEX ACTION OF THE SPINAL CORD. 351 
 
 contact of a hair or a feather, or even the jarring of the table on 
 which the animal is placed. That the convulsions in cases of 
 poisoning by strychnine are always of a reflex character, and never 
 spontaneous, is shown by the following fact first noticed by Bernard,' 
 viz., that if a frog be poisoned after division of the posterior roots 
 of all the spinal nerves, while the anterior roots are left untouched, 
 death takes place as usual but is not preceded by any convulsions. 
 In this instance the convulsions are absent simply because, owing 
 to the division of the posterior roots, external irritations cannot be 
 communicated to the cord. 
 
 The reflex action, above described, may be seen very distinctly 
 in the human subject, in certain cases of disease of the spinal cord. 
 If the upper portion of the cord be disintegrated by inflammatory 
 softening, so that its middle and lower portions lose their natural 
 connection with the brain, paralysis of voluntary motion and loss 
 of sensation ensue in all parts of the body below the seat of the 
 anatomical lesion. Under these conditions, the patient is incapable 
 of making any muscular exertion in the paralyzed parts, and is 
 unconscious of any injury done to the integument in the same 
 region. Notwithstanding this, if the soles of the feet be gently 
 irritated with a feather, or with the point of a needle, a convulsive 
 twitching of the toes will often take place, and even retractile move- 
 ments of the leg and thigh, altogether without the patient's know- 
 ledge. Such movements may frequently be excited by simply 
 allowing the cool air to come suddenly in contact with the lower 
 extremities. We have repeatedly witnessed these phenomena, in 
 a case of disease of the spinal cord where the paralysis and in- 
 sensibility of the lower extremities were complete. Many other 
 similar instances are reported by various authors^ 
 
 The existence of this reflex action of the cord has enabled the 
 physiologist to ascertain several other important facts concerning 
 the mode of operation of the nervous system. M, Bernard has 
 demonstrated,^ by a series of extremely ingenious experiments on 
 the action of poisonous substances, 1st, that the irritability of the 
 muscles may be destroyed, while that of the nerves remains unal- 
 tered ; and 2d, that the motor and sensitive nervous filaments may 
 each be paralyzed independently of each other. The above facts 
 are shown by the three following experiments: — 
 
 ' Lecjons sur les eflFets des Substances toxiques et medicamenteuses, Paris, 1857, 
 p. 357. 
 
 ^ Lecjons sur le.s effets des Substances toxiques et nielicanienteuses, Chaps. 23 
 and 24. 
 
352 
 
 THE SPIXAL COBD. 
 
 1. In a living frog (Fig. 137), the sciatic nerve (xV) is exposed in the 
 back part of the thigh, after which a ligature is passed underneath 
 
 it and drawn tight around the 
 ^^" bone and the remaining soft 
 
 parts. In this way the circu- 
 lation is entirely cut off" from 
 the limb {d)^ which remains 
 in connection with the trunk 
 only by means of the sciatic 
 nerve. A solution of sulpho- 
 cyanide of potassium is then 
 introduced beneath the skin 
 of the back, at /, in sufficient 
 quantity to produce its speci- 
 fic effect. The poison is then 
 absorbed, and is carried by 
 the circulation throughout the 
 trunk and the three extremi- 
 ties a, 6, c; while it is prevented 
 from entering the limb c?, by 
 the ligature which has been 
 placed about the thigh. Sul- 
 phocyanide of potassium pro- 
 duces paralysis, as we have 
 previously mentioned, by act- 
 ing directly upon the muscu- 
 lar tissue. Accordingly, a gal- 
 vanic discharge passed through 
 the limbs a, 5, and c, produces 
 no contraction in them, while 
 the same stimulus, applied to 
 d, is follow^ed by a strong and healthy reaction. But at the moment 
 when the irritation is applied to the poisoned limbs a, h, and c, 
 though no visible effect is produced in them, an active movement 
 takes place in the healthy limb, d. This can only be owing to a 
 reflex action of the spinal cord, originating in the integument of a, 
 6, and c, and transmitted, by sensitive and motor filaments, through 
 the cord, to d. While the muscles of the poisoned limbs, therefore, have 
 been directly paralyzed, the nerves of the same parts have retained their 
 irritability. 
 
 2. If a frog be poisoned with woorara by simply placing the 
 
REFLEX ACTION OF THE SPINAL CORD. 353 
 
 poison under the skin, no reflex action of the spinal cord can be 
 demonstrated after death. We have already shown, from experi- 
 ments detailed in Chapter II., that this substance destroys the irrita- 
 bility of the motor nerves, without affecting that of the muscles. In 
 the above instance, therefore, where the reflex action is abolished, its 
 loss may be owing to a paralysis of both motor and sensitive fila- 
 ments, or to that of the motor filaments alone. The following experi- 
 ment, however, shows that the motor filaments are the only ones 
 affected. If a frog be prepared as in Fig. 137, and poisoned by the 
 introduction of woorara at /, when the limb d is irritated its own 
 muscles react, while no movement takes place in a, 5, or c; but if 
 the irritation be applied to a, &, or c, reflex movements are imme- 
 diately produced in d. In the poisoned limbs, there/ore, while the 
 motor nerves have been paralyzed, the sensitive filaments have retained 
 their irritability. 
 
 3. If a frog be poisoned with strychnine, introduced underneath 
 the skin in sufficient quantity, death takes place after general con- 
 vulsions, which are due, as we have seen above, to an unnatural 
 excitability of the reflex action. This is followed, however, by a 
 paralysis of sensibility, so that after death no reflex movements 
 can be produced by irritating the skin or even the posterior roots 
 of the spinal nerves. But if the anterior roots, or the motor nerves 
 themselves be galvanized, contractions immediately take place in 
 the corresponding muscles. In this case, therefore, the sensitive fila- 
 ments have been paralyzed, while the motor filaments and the muscles 
 have retained their irritability. 
 
 We come now to investigate the reflex action of the spinal cord, 
 as it takes place in a healthy condition during life. This action 
 readily escapes notice, unless our attention be particularly directed 
 to it, because the sensations which we are constantly receiving, and 
 the many voluntary movements which are continually executed, 
 serve naturally to mask those nervous phenomena which take place 
 without our immediate knowledge, and over which we exert no 
 voluntary control. Such phenomena, however, do constantly take 
 place, and are of extreme physiological importance. If the surface 
 of the skin, for example, be at any time unexpectedly brought in 
 contact with a heated body, the injured part is often withdrawn by 
 a rapid and convulsive movement, long before we feel the pain, or 
 even understand fairly the cause of the involuntary act. If the 
 body, by any accident, suddenly and unexpectedly lose its balance, 
 the limbs are thrown into a position calculated to protect the ex- 
 23 
 
354 THE SPIXAL CORD. 
 
 posed parts and to break the fall, by a similar involuntary and in- 
 stantaneous movement. The brain does not act in these cases, for 
 there is no intentional character in the movement, nor even any 
 complete consciousness of its object. Everything indicates that it 
 is the immediate result of a simple reflex action of the spinal cord. 
 
 The cord exerts also an important and constant influence upon 
 the sphincter muscles. The sphincter ani is habitually in a state of 
 contraction, so that the contents of the intestine are not allowed to 
 escape. When any external irritation is applied to the anus, or 
 whenever the feces present themselves internally, the sphincter 
 contracts involuntarily, and the discharge of the feces is prevented. 
 This habitual closure of the sphincter depends on the reflex action 
 of the spinal cord. It is entirely an involuntary act, and will con- 
 tinue, in the healthy condition, during profound sleep, as complete 
 and efficient as in the waking state. 
 
 When the rectum, however, has become filled by the accumula- 
 tion of feces from above, the nervous action changes. Then the 
 impression produced on the mucous membrane of the distended 
 rectum, conveyed to the spinal cord, causes at the same time re- 
 laxation of the sphincter and contraction of the rectum itself; so 
 that a discharge of the feces consequently takes place. 
 
 Now all these actions are to some extent under the control of 
 sensation and volition. The distended state of the rectum is usually 
 accompanied by a distinct sensation, and the resistance of the 
 sphincter may be voluntarily prolonged for a certain period, just as 
 the respiratory movements, which are usually involuntary, may be 
 intentionally hastened or retarded, or even temporarily suspended. 
 But this voluntary power over the sphincter and the rectum is 
 limited. After a time the involuntary impulse, growing more and 
 more urgent with the increased distension of the rectum, becomes 
 irresistible; and the discharge finally takes place by the simple 
 reflex action of the spinal cord. 
 
 If the spinal cord be injured in its middle or upper portions, the 
 sensibility and voluntary action of the sphincter is lost, because its 
 connection with the brain has been destroyed. The evacuation 
 then takes place at once, by the ordinary mechanism, as soon as 
 the rectum is filled, but without any knowledge on the part of the 
 patient. The discharges are then said to be " involuntary and un- 
 conscious." 
 
 If the irritability of the cord, on the other hand, be exaggerated 
 by disease, while its connection with the brain remains entire, the 
 
KEFLEX ACTION OF THE SrilSTAL CORD. 355 
 
 distension of the rectum is announced by the usual sensation, but 
 the reflex impulse to evacuation is so urgent that it cannot be 
 controlled bj the will, and the patient is compelled to allow it to 
 take place at once. The discharges are then said to be simply 
 '* involuntary." 
 
 Finally, if the substance of the spinal cord be extensively de- 
 stroyed by accident or disease, the sphincter is permanently relaxed. 
 The feces are then evacuated almost continuously, without any 
 knowledge or control on the part of the patient, as fast as they 
 descend into the rectum from the upper portions of the intestine. 
 
 Injury of the spinal cord produces a somewhat different effect 
 on the urinary bladder. Its muscular fibres are directly para- 
 lyzed ; and the organ, being partially protected by elastic fibres, 
 both at its own orifice and along the urethra, becomes gradually 
 distended by urine from the kidneys. The urine then overcomes 
 the elasticity of the protecting fibres, by simple force of accumula- 
 tion, and afterward dribbles away as fast as it is excreted by the 
 kidneys. Paralysis of the bladder, therefore, first causes a perma- 
 nent distension of the organ, which is afterward followed by a 
 continuous, passive, and incomplete discharge of its contents. 
 
 Injury of the spinal cord produces also an important, though 
 probably an indirect effect on nutrition, secretion, animal heat, &c., 
 in the paralyzed parts. Diseases of the cord which result in its 
 softening or disintegration, are notoriously accompanied by consti- 
 pation, often of an extremely obstinate character. In complete 
 paraplegia, also, the lower extremities become emaciated. The 
 texture and consistency of the muscles are altered, and the animal 
 temperature is considerably reduced. All such disturbances of 
 nutrition, however, which follow almost invariably upon local para- 
 lysis are no doubt immediately owing to the inactive condition of 
 the muscles; a condition which naturally induces debility of the 
 circulation, and consequently of all those functions which are 
 dependent upon it. 
 
 It is less easy to explain the connection between injury of the 
 spinal cord and inflammation of the urinary passages. It is, how- 
 ever, a matter of common observation among pathologists, that 
 injury or disease of the cord, particularly in the dorsal and upper 
 lumbar regions, is soon followed by catarrhal inflammation of the 
 urinary passages. This gives rise to an abundant production of 
 altered mucus, which in its turn, by causing an alkaline fermenta- 
 tion in the urine contained in the bladder, converts it into an irri- 
 
356 THE SPINAL CORD. 
 
 tating and ammoniacal liquid, which reacts upon the nnucous 
 membrane and aggravates the previous inflammation. 
 
 We find, therefore, that the spinal cord, in its character of a 
 nervous centre, exerts a general protective action over the whole 
 body. It presides over the involuntary movements of the limbs 
 and trunk ; it regulates the action of the sphincters, the rectum, 
 and the bladder; while at the same time it exerts an indirect influ- 
 ence on the nutritive changes in those parts which it supplies with 
 nerves. 
 
THE BRAIN. 857 
 
 CHAPTER IV. 
 
 THE BRAIN. 
 
 By the brain, or encephalon, as it is sometimes called, we mean all 
 that portion of the nervous system which is situated within the 
 cavity of the cranium. It consists, as we have already shown, of 
 a series of different ganglia, connected with each other by transverse 
 and longitudinal commissures. 
 
 Since we have found the functions of sensation and motion, or 
 sensibility and excitability, so distinctly separated in the spinal 
 cord, we should expect to find the same distinction in the interior 
 of the brain. These two properties have indeed been found to be 
 distinct from each other, so far as they exist at all, in the encephalic 
 mass ; but it is a very remarkable fact that they are both confined 
 to very small portions of the brain, in comparison with its entire 
 bulk. According to the investigations of Longet, neither the 
 olfactory ganglia, the corpora striata, the optic thalami, the tuber- 
 cula quadrigemina, nor the white or gray substance of the cerebrum 
 or the cerebellum, are in the least degree excitable. Mechanical 
 irritation of these parts does not produce the slightest convulsive 
 movement in the muscles below. The application of caustic liquids 
 and the passage of galvanic currents are equally without effect. 
 The only portions of the brain in which irritation is followed by 
 convulsive movements are the anterior surface of the medulla ob- 
 longata, the tuber annulare, and the lower part of the crura cerebri; 
 that is, the lower and central parts of the brain, containing continu- 
 ations of the anterior columns of the cord. On the other hand, 
 neither the olfactory ganglia, the corpora striata, the tubercula 
 quadrigemina nor the white or gray substance of the cerebrum or 
 cerebellum, give rise, on being irritated, to any painful sensation. 
 The only sensitive parts are the posterior surfiice of the medulla 
 oblongata, the restiform bodies, the processus e cerebello ad testes, 
 and the upper part of the crura cerebri ; that is, those portions of 
 
358 THE BRAIN". 
 
 the base of the brain which contain prolongations of the posterior 
 columns of the cord 
 
 The most central portions of the nervous system, therefore, and 
 particularly the gray matter, are destitute of both excitability and 
 sensibility. It is only those portions which serve to conduct sen- 
 sations and nervous impulses that can be excited by mechanical 
 irritation; not the ganglionic centres themselves, which receive and 
 originate the nervous impressions. 
 
 "We shall now study in succession the different ganglia of which 
 the brain is composed. 
 
 OLFACTORY GANGLIA. 
 
 These ganglia, which in some of the lower animals are very 
 large, corresponding in size with the extent of the Schneiderian 
 mucous membrane and the acuteness of the sense of smell, are very 
 small in the human subject. They are situated on the cribriform 
 plate of the ethmoid bone, on each side of the crista galli, just be- 
 neath the anterior lobes of the cerebrum. They send their nerves 
 through the numerous perforations which exist in the ethmoid bone 
 at this part, and are connected with the base of the brain by two 
 longitudinal commissures. The olfactory ganglia with their com- 
 missures are sometimes spoken of as the "olfactory nerves." They 
 are not nerves, however, but ganglia, since they are mostly com- 
 posed of gray matter ; and the term " olfactory nerves" can be 
 properly applied only to the filaments which originate from them, 
 and which are afterward spread out in the substance of the Schnei- 
 derian mucous membrane. 
 
 It has been found difficult to determine the function of these 
 ganglia by direct experiment on the lower animals. They may be 
 destroyed by means of a strong needle introduced through the bones 
 of the cranium ; but the signs of the presence or absence of the 
 sense of smell, after such an operation, are too indefinite to allow us 
 to draw from them a decided conclusion. The anatomical distribu- 
 tion of their nerves, however, and the evident correspondence which 
 exists, in different species of animals, between their degree of de- 
 velopment and that of the external olfactory organs, leaves no doubt 
 as to their true function. They are the ganglia of the special sense 
 of smell, and are not connected, in any appreciable degree, with 
 
OPTIC THALAMI, — CORPORA STRIATA. — HEMISPHERES. 859 
 
 ordinary sensibility, nor with the production of voluntary move- 
 ments. 
 
 OFTIC THALAMI. 
 
 These bodies are not, as their name would imply, the ganglia of 
 vision. Longet has found that the power of sight and the sensi- 
 bility of the pupil both remain, in birds, after the optic thalami 
 have been thoroughly disorganized ; and that artificial irritation of 
 the same ganglia has no effect in producing either contraction or 
 dilatation of the pupil. The optic thalami, however, according to 
 the same observer, have a peculiar crossed action upon the volun- 
 tary movements. If both hemispheres and both optic thalami be 
 removed in the rabbit, the animal is still capable of standing and 
 of "using his limbs in progression. But if the right optic thalamus 
 alone be removed, the animal falls at once upon his left side; and 
 if the left thalamus be destroyed, a similar debility is manifest on 
 the right side of the body. In these instances there is no absolute 
 paralysis of the side upon which the animal falls, but rather a 
 simple want of balance between the two opposite sides. The exact 
 mechanism of this peculiar functional disturbance is not well 
 understood; and but little light has yet been thrown, either by 
 direct experiment or by the facts of comparative anatomy, on the 
 real function of the optic thalami. 
 
 CORPORA STRIATA. 
 
 The function of these ganglia is equally uncertain with that of 
 the preceding. They are traversed, as we have already seen, by 
 fibres coming from the anterior columns of the cord; and they are 
 connected, by the continuation of these fibres, with the gray sub- 
 stance of the hemispheres. They have, therefore, in all probability, 
 like the optic thalami, some connection with sensation and volition; 
 but the precise nature of this connection is at present altogether 
 unknown. 
 
 HEMISPHERES. 
 
 The hemispheres, or the cerebral ganglia, constitute in the 
 human subject about nine tenths of the whole mass of the brain. 
 
360 THE BRAIN. 
 
 Throughout their whole extent they are entirely destitute, as we 
 have already mentioned, of both sensibility and excitability. Both 
 the white and gray substance may be wounded, burned, lacerated, 
 crushed, or galvanized in the living animal, without exciting any 
 convulsive movement or any apparent sensation. In the human 
 subject a similar insensibility has been observed when the sub- 
 stance of the hemispheres has been exposed by accidental violence, 
 or in the operation of trephining. 
 
 Yery severe mechanical injuries may also be inflicted upon the 
 hemispheres, even in the human subject, without producing any 
 directly fatal result. One of the most remarkable instances of this 
 fact is a case reported by Dr. William Detmold, of New York,' in 
 which an abscess in the anterior lobe of the brain was opened by an 
 incision passing through the cerebral substance, not only without 
 any immediate bad effect, but with great temporary relief to the 
 patient. This was the case of a laborer who was struck on the left 
 side of the forehead by a piece of falling timber, which produced a 
 compound fracture of the skull at this part. One or two pieces 
 of bone afterward became separated and were removed, and the 
 wound subsequently healed. Nine weeks after the accident, how- 
 ever, headache and drowsiness came on ; and the latter symptom, 
 becoming rapidly aggravated, soon terminated in complete stupor. 
 At this time, the existence of an abscess being suspected, the 
 cicatrix, together with the adherent portion of the dura mater, was 
 dissected away, several pieces of fractured bone removed, and the 
 surface of the brain exposed. A knife was then passed into the 
 cerebral substance, making a wound one inch in length and half 
 an inch in depth, when the abscess was reached and about liij of 
 pus discharged. I^he patient immediately aroused from his coma- 
 tose condition, so that he was able to speak; and in a few days 
 recovered, to a very considerable extent, his cheerfulness, intelli- 
 gence, and appetite. Subsequently, however, the collection of pus 
 returned, accompanied by a renewal of the previous symptoms; 
 and the patient finally died at the end of seven weeks from the 
 time of opening the abscess. 
 
 Another and still more striking instance of recovery from severe 
 injury of the brain is reported by Prof. H. J. Bigelow in the 
 American Journal of Medical Sciences for July, 1850. In this case, a 
 pointed iron bar, three feet and a half in length, and one inch and a 
 
 ' Am. Joiirn. of Med. Sci., January, 1850. 
 
HEMISPHERES. 361 
 
 quarter in diameter, was driven through the patient's head by the 
 premature blasting of a rock. The bar entered the left side of the 
 face, just in front of the angle of the jaw, and passed obliquely 
 upward, inside the zygomatic arch and through the anterior part 
 of the cranial cavity, emerging from the top of the frontal bone on 
 the median line, just in front of the point of union of the coronal 
 and sagittal sutures. The patient was at first stunned, but soon 
 recovered himself so far as to be able to converse intelligently, rode 
 home in a common cart, and with a little assistance walked up stairs 
 to his room. He became delirious within two days after the acci- 
 dent, and subsequently remained partly delirious and partly coma- 
 tose for about three weeks. He then began to improve, and at the 
 end of rather more than two months from the date of the injury, 
 was able to walk about. At the end of sixteen months he was in 
 perfect health, with the wounds healed, and with the mental and 
 bodily functions entirely unimpaired, except that sight was perma- 
 nently lost in the eye of the injured side. 
 
 The hemispheres, furthermore, are not the seat of sensation or of 
 volition, nor are they immediately essential to the continuance of 
 life. In quadrupeds, the complete removal of the hemispheres is 
 attended with so much hemorrhage that the operation is generally 
 fatal from this cause within a few minutes. In birds, however, it 
 may be performed without any immediate danger to life. Longet 
 has removed the hemispheres in pigeons and fowls, and has kept 
 these animals afterward for several days, with most of the organic 
 functions unimpaired. We have frequently performed the same 
 experiment upon pigeons, with a similarly favorable result. 
 
 The effect of this mutilation is simply to plunge the animal into 
 a state of profound stupor, in which he is almost entirely inatten- 
 tive to surrounding objects. The bird remains sitting motionless 
 upon his perch, or standing upon the ground, with the eyes closed, 
 and the head sunk between the shoulders. (Fig. 138.) The plu- 
 mage is smooth and glossy, but is uniformly expanded, by a kind 
 of erection of the feathers, so that the body appears somewhat 
 puffed out, and larger than natural. Occasionally the bird opens 
 his eyes with a vacant stare, stretches his neck, perhaps shakes his 
 bill once or twice, or smooths down the feathers' upon his shoulders, 
 and then relapses into his former apathetic condition. This state 
 of immobility, however, is not accompanied by the loss of sight, of 
 hearing, or of ordinary sensibility. All these functions remain, as 
 well as that of voluntary motion. If a pistol be discharged behind 
 
362 
 
 THE BRAIN. 
 
 the back of the animal, he at once opens his eyes, moves his head 
 half round, and gives evident signs of having heard the report; but 
 he immediately becomes quiet, again, and pays no farther attention 
 to it. Sight is also retained, since the bird will sometimes fix its 
 
 Fig. 138. 
 
 PiGEOX, AFTER REMOVAL OF THE HEMISPHERES. 
 
 eye on a particular object, and watch it for several seconds together. 
 Longet has even found that by moving a lighted candle before the 
 animal's eyes in a dark place, the head of the bird will often follow 
 the movements of the candle from side to side or in a circle, showing 
 that the impression of light is actually perceived by the sensoriura. 
 Ordinary sensation also remains, after removal of the hemispheres, 
 together with voluntary motion. If the foot be pinched with a 
 pair of forceps, the bird becomes partially aroused, moves uneasily 
 once or twice from side to side, and is evidently annoyed at the 
 irritation. 
 
 The animal is still capable, therefore, after removal of the hemi- 
 spheres, of receiving sensations from external objects. But these 
 sensations appear to make upon him no lasting impression. He is 
 incapable of connecting with his perceptions any distinct succession 
 of ideas. He hears, for example, the report of a pistol, but he is not 
 alarmed by it ; for the sound, though distinctly enough perceived, 
 does not suggest any idea of danger or injury. There is accord- 
 ingly no power of forming mental associations, nor of perceiving 
 the relation between external objects. The memory, more particu- 
 larly, is altogether destroyed, and the recollection of sensations is 
 not retained from one moment to another. The limbs and muscles 
 are still under the control of the will ; but the will itself is inactive. 
 
HEMISPHERES. 363 
 
 because apparently it lacks its usual mental stimulus and direction. 
 The powers whicli have been lost, therefore, by destruction of the 
 cerebral hemispheres, are altogether of a mental or intellectual 
 character; that is, the power of comparing with each other different 
 ideas, and of perceiving the proper relation between them. 
 
 The same result is well known to follow, in the human subject, 
 from injury or disease of these parts. A disturbance of the mental 
 powers has long been recognized as the ordinary consequence of 
 lesions of the brain. In cases of impending apoplexy, for example, 
 or of softening of the cerebral substance, among the earliest and 
 most constant phenomena is a loss or impairment of the memory. 
 The patient forgets the names of particular objects or of particular 
 persons ; or he is unable to calculate numbers with his usual facility. 
 His mental derangement is often shown in the undue estimate which 
 he forms of passing events. He is no longer able to appreciate the 
 true relation between different objects and different phenomena. 
 Thus, he will show an exaggerated degree of solicitude about a 
 trivial occurrence, and will pay no attention to other matters of 
 real importance. As the difficulty increases, he becomes careless 
 of the directions and advice of his attendants, and must be watched 
 and managed like a child or an imbecile. After a certain period, 
 he no longer appreciates the lapse of time, and even loses the dis- 
 tinction between day and night. Finally, when the injury to the 
 hemispheres is complete, the senses may still remain active and 
 impressible, while the patient is completely deprived of intelligence, 
 memory, and judgment. 
 
 If we examine the comparative development of the hemispheres 
 in different species of animals, and in different races of men, we 
 shall find that the size of these ganglia corresponds very closely 
 with the degree of intelligence possessed by the individual. We 
 have already traced, in a preceding chapter, the gradual increase 
 in size of the hemispheres in fish, reptiles, birds and quadrupeds: 
 four classes of animals which may be arranged, with regard to the 
 amount of intelligence possessed by each, in precisely the same 
 order of succession. Among quadrupeds, the elephant has much 
 the largest and most perfectly formed cerebrum, in proportion to 
 the size of the entire body; and of all quadrupeds he is proverbially 
 the most intelligent and the most teachable. It is important to 
 observe, in this connection, that the kind of intelligence which 
 characterizes the elephant and some other of the lower animals, 
 and which most nearly resembles that of man, is a teachable intelli- 
 
364 THE BRAIN. 
 
 gence; a very different thing from the intelligence which depends 
 upon instinct, such as that of insects, for example, or birds of pas- 
 sage. Instinct is unvarying, and always does the same thing in the 
 same manner, with endless repetition ; but intelligence is a power 
 which adapts itself to new circumstances, and enables its possessor, 
 by comprehending and retaining new ideas, to profit by experience. 
 It is this quality which distinguishes the higher classes of animals 
 from the lower; and which, in a very much greater degree, con- 
 stitutes the intellectual superiority of man himself. The size 
 of the cerebrum in man is accordingly very much greater, in pro- 
 portion to that of the entire body, than in any of the lower animals; 
 while other parts of the brain, on the contrary, such as the olfactory 
 ganglia or the optic tubercles, are frequently smaller in him than 
 in them. For while man is superior in general intelligence to all 
 the lower animals, he is inferior to many of them in the acuteness 
 of tlie special senses. 
 
 As a general rule, also, the size of the cerebrum in different 
 races and in different individuals corresponds with the grade of 
 their intelligence. The size of the cranium, as compared with that 
 of the face, is smallest in the savage negro and Indian tribes; larger 
 in the civilized or semi-civilized Chinese, Malay, Arab, and Japan- 
 ese; while it is largest of all in the enlightened European races. 
 This difference in the development of the brain is not probably an 
 effect of long-continued civilization or otherwise; but it is, on the 
 contrary, the superiority in cerebral development which makes 
 some races readily susceptible of civilization, while others are 
 either altogether incapable of it, or can only advance in it to a 
 certain limit. Although all races therefore may, perhaps, be said 
 to start from the same level of absolute ignorance, yet after the 
 lapse of a certain time one race will have advanced farther in 
 civilization than another, owing to a superior capacity for improve- 
 ment, dependent on original organization. 
 
 The same thing is true with regard to different individuals. At 
 birth, all men are equally ignorant ; and yet at the end of a certain 
 period one will have acquired a very much greater intellectual 
 power than another, even under similar conditions of training, 
 education, &c. He has been able to accumulate more information 
 from the same sources, and to use the same experience to better 
 advantage than his associates ; and the result of this is a certain 
 intellectual superiority, which becomes still greater by its own 
 exercise. This superiority, it will be observed, lies not so much 
 
HEMISPHERES. 365 
 
 in tlie power of perceiving external objects and events, and of 
 recognizing the connection between tliem, as in that of drawing 
 conclusions from one fact to another, and of adapting to new com- 
 binations the knowledge which has already been acquired. 
 
 It is this particular kind of intellectual difference, existing in a 
 marked degree between animals, races, and individuals, which cor- 
 responds with the difference in development of the cerebral hemi- 
 spheres. We have, therefore, evidence from three different sources 
 that the cerebral hemispheres are the seat of the reasoning powers,. 
 or of the intellectual faculties proper. First, when these ganglia 
 are removed, in the lower animals, the intellectual faculties are the 
 only ones which are lost. Secondly, injury to these ganglia, in the 
 human subject, is followed by a corresponding impairment of the 
 same faculties. Thirdly, in different species of animals, as well as 
 in different races of men and in different individuals, the develop- 
 ment of these faculties is in proportion to that of the cerebral 
 hemispberes. 
 
 When we say, however, that the hemispheres are the seat of the 
 intellectual faculties, of memory, reason, judgment, and the like, 
 we do not mean that these faculties are, strictly speaking, located 
 in the substance of the hemispheres, or that they belong directly to 
 the matter of which the hemispheres are composed. The hemi- 
 spherical ganglia are simply the instruments through which the 
 intellectual powers manifest themselves, and which are accordingly 
 necessary to their operation. If these instruments be imperfect in 
 structure, or be damaged in any manner by violence or disease, the 
 manifestations of intelligence are affected in a corresponding degree. 
 So far, therefore, as the mental faculties are the subject of physio- 
 logical research and experiment, they are necessarily connected 
 with the hemispherical ganglia; and the result of investigation 
 shows this connection to be extremely intimate and important in 
 its character. 
 
 There are, however, various circumstances which modify, in 
 particular cases, the general rule given above, viz., that the larger 
 the cerebrum the greater the intellectual superiority. The func- 
 tional activity of the brain is modified, no doubt, by its texture as 
 well as by its size ; and an increased excitability may compensate, 
 partially or wholly, for a deficiency in bulk. This fact is some- 
 times illustrated in the case of idiots. There are instances where 
 idiotic children with small brains are less imbecile and helpless 
 than others with a larger development, owing to a certain vivacity 
 
366 
 
 THE BRAIl^. 
 
 and impressibility of organization which take the place, to a cer- 
 tain extent, of the purely intellectual faculties. 
 
 This was the case, in a marked degree, with a pair of dwarfed 
 and idiotic Central American children, who were exhibited a few 
 years ago in various parts of the United States, under the name of 
 the "Aztec children." They were a bo}' and a girl, aged respectively 
 about seven and five years. The boy was 2 feet 9| inches high, and 
 weighed a little over 20 pounds. The girl was 2 feet 5| inches 
 high, and weighed 17 pounds. Their bodies were tolerably well 
 proportioned, but the cranial cavities, as shown by the accompan}^- 
 ing portraits, were extremely small. 
 
 Fig. 139. 
 
 Aztec Children.— Taken from life. 
 
 The antero-posterior diameter of the boy's head was only 4| 
 inches, the transverse diameter less than 4 inches. The antero- 
 posterior diameter of the girl's head was 4J inches, the transverse 
 diameter only 3| inches. The habits of these children, so far as 
 regards feeding and taking care of themselves, were those of chil- 
 dren two or three years of age. They were incapable of learning 
 to talk, and could only repeat a few isolated words. Notwithstand- 
 ing, however, the extremely limited range of their intellectual 
 powers, these children were remarkably vivacious and excitable. 
 While awake they were in almost constant motion, and any new 
 object or toy presented to them immediately attracted their atten- 
 tion, and evidently awakened a lively curiosity. They were ac- 
 cordingly easily influenced by proper management, and understood 
 readily the meaning of those who addressed them, so far as this 
 meaning could be conveyed by gesticulation and the tones of the 
 voice. Their expression and general appearance, though decidedly 
 idiotic, were not at all disagreeable or repulsive ; and they were 
 
HEMISPHEEES. 367 
 
 much less troublesome to the persons who had them in charge than 
 is often the case with idiots possessing a larger cerebral development. 
 
 It may also be observed that the purely intellectual or reasoning 
 powers are not the only element in the mental superiority of 
 certain races or of particular individuals over their associates. 
 There is also a certain rapidity of perception and strength of will 
 which may sometimes overbalance greater intellectual acquirements 
 and more cultivated reasoning powers. These, however, are differ- 
 ent faculties from the latter ; and occupy, as we shall hereafter see, 
 different parts of the encephalon. 
 
 A very remarkable physiological doctrine, dependent partly on 
 the foregoing facts, was brought forward some years ago by Gall 
 and Spurzheim, under the name of Phrenology. These observers 
 recognized the fact that the intellectual powers are undoubtedly 
 seated in the brain, and that the development of the brain is, as a 
 general rule, in correspondence with the activity of these powers. 
 They noticed also that in other parts of the nervous system, different 
 functions occupy different situations ; and regarding the mind as 
 made up of many distinct mental faculties, they conceived the idea 
 that these different faculties might be seated in different parts of 
 the cerebral mass. If so, each separate portion of the brain would 
 undoubtedly be more or less developed in proportion to the activity 
 of the mental trait or faculty residing in it. The shape of the head 
 would then vary in different individuals, in accordance with their 
 mental peculiarities; and the character and endowments of the 
 individual might therefore be estimated from an examination of 
 the elevations and depressions on the surface of the cranium. 
 
 Accordingly, the authors of this doctrine endeavored, by examin- 
 ing the heads of various individuals whose character was already 
 known, to ascertain the location of the different mental faculties. 
 In this manner they finally succeeded, as they supposed, in accom- 
 plishing their object; after which they prepared a chart, in which 
 the surface of the cranium was mapped out into some thirty or forty 
 different regions, corresponding with as many different mental traits 
 or faculties. With the assistance of this chart it was thought that 
 phrenology might be practised as an art ; and that, by one skilled 
 in its application, the character of a stranger might be discovered 
 by simply examining the external conformation of his head. 
 
 We shall not expend much time in discussing the claims of phre- 
 nology to rank as a science or an art, since we believe that it has 
 of late years been almost wholly discarded by scientific men, owing 
 
368 THE BRAIN. 
 
 to the very evident deficiencies of the basis upon which it was 
 founded. Passing over, therefore, many minor details, we will 
 merely point out, as matters of physiological interest, the principal 
 defects which must always prevent the establishment of phrenology 
 as a science, and its application as an art. 
 
 First, though we have no reason for denying that different parts 
 of the brain may be occupied by different intellectual faculties, 
 there is no direct evidence which would show this to be the case. 
 Phrenologists include, in those parts of the brain which they em- 
 ploy for examination, both the cerebrum and cerebellum ; and they 
 justly regard the external parts of these bodies, viz., the layer of 
 gray matter which occupies their surface, as the ganglionic portion 
 in which must reside more especially the nervous functions which 
 they possess. But this layer of gray matter, in each principal por- 
 tion of the brain, is continuous throughout. There is no anatomical 
 division or limit between its different parts, as there are between 
 the different ganglia in other portions of the nervous system ; and 
 consequently such divisions of the cerebrum and cerebellum must 
 be altogether arbitrary in character, and not dependent on any 
 anatomical basis. 
 
 Secondly, the only means of ascertaining the location of the 
 different mental traits, supposing them to occupy different parts of 
 the brain, would be that adopted by Gall and Spurzheim, viz., to 
 make an accurate comparison, in a sufficient number of cases, of the 
 form of the head in individuals of known character. But the prac- 
 tical difficulty of accomplishing this is very great. It requires a 
 long acquaintance and close observation to learn accurately the 
 character of a single person; and it is in this kind of observation, 
 more than in any other, that we are proverbially liable to mis- 
 takes. It is extremely improbable, therefore, that either Gall or 
 Spurzheim could, in a single lifetime, have accomplished this com- 
 parison in so many instances as to furnish a reliable basis for the 
 construction of a phrenological chart. 
 
 A still more serious practical difficulty, however, is the following. 
 The different intellectual faculties being supposed to reside in the 
 layer of gray substance constituting the surfaces of the cerebrum 
 and cerebellum, they must of course be distributed throughout this 
 layer, wherever it exists. Gall and Spurzheim located all the mental 
 faculties in those parts of the brain which are accessible to external 
 exploration. An examination of different sections of the brain 
 will show, however, that the greater portion of the gray substance 
 is so placed, that its quantity cannot be estimated by an external 
 
HEMISPHEEES. 
 
 869 
 
 Fig. 140. 
 
 examination througli the skull. The only portions which are ex- 
 posed to such an examination are the upper and lateral portions of 
 the convexities of the hemispheres, together with the posterior edge 
 and part of the under surface of the cerebellum. (Fig. 140.) A 
 verj extensive portion of the cerebral 
 surface, however, remains concealed in 
 such a manner that it cannot possibly be 
 subjected to examination, viz., the entire 
 base of the brain, with the under surface 
 of the anterior and middle lobes (1,2 ); 
 the upper surface of the cerebellum (3) 
 and the inferior surface of the posterior 
 lobe of the cerebrum which covers it (4); 
 that portion of the cerebellum situated 
 above the medulla oblongata (5); and the 
 two opposite convoluted surfaces in the 
 fissure of Sylvius (e, 7), where the ante- 
 rior and middle lobes of the cerebrum 
 lie in contact with each other. The whole 
 
 extent, also, of the cerebral surfaces which are opposed to each 
 other in the great longitudinal fissure (Fig. 141), throughout its 
 entire length, are equally protected by their 
 position, and concealed from external exa- 
 mination. The whole of the convoluted 
 surface of the brain must, however, be re- 
 garded as of equal importance in the distri- 
 bution of the mental qualities ; and yet it is 
 evident that not more than one-third or one- 
 quarter of this surface is so placed that it 
 can be examined by external manipulation. 
 It must furthermore be recollected that the 
 gray matter of the cerebrum and cerebellum 
 is everywhere convoluted, and that the 
 convolutions penetrate to various depths 
 in the substance of the brain. Even if we were able to feel, 
 therefore, the external surface of the brain itself, it would not be 
 the entire convolutions, but only their superficial edges, that we 
 should really be able to examine. And yet the amount of gray 
 matter contained in a given space depends quite as much upon the 
 depth to which the convolutions penetrate, as upon the prominence 
 of their edges. 
 24 
 
 Diagram of the B k A i n in situ, 
 showing those portious which are ex- 
 posed to examination. 
 
 Fig. 141. 
 
 Transverse section of B r a t x , 
 showing depth of great longi- 
 tudinal fissure, at a. 
 
370 THE BRAIN. 
 
 While phrenology, therefore, is partially founded upon acknow- 
 ledged physiological facts, there are yet essential deficiencies in its 
 scientific basis, as well as insurmountable difficulties in the way of 
 its practical application. 
 
 CEREBELLUM. 
 
 The cerebellum is the second ganglion of the encephalon, in 
 respect of size. If it be examined, moreover, in regard to the form 
 and disposition of its convolutions, it will be seen that these are 
 much more complicated and more numerous than in the cerebrum, 
 and penetrate much deeper into its substance. Though the cerebel- 
 lum therefore is smaller, as a whole, than the cerebrum, it contains, 
 in proportion to its size, a much larger quantity of gray matter. 
 
 In examining the comparative development of the brain, also, in 
 different classes and species of animals, we find that the cerebellum 
 nearly always keeps pace, in this respect, with the cerebrum. These 
 facts would lead us to regard it as a ganglion hardly secondary in 
 importance to the cerebrum itself. 
 
 Physiologists, however, have thus far failed to demonstrate the 
 nature of its function with the same degree of precision as that of 
 many other parts of the brain. The opinion of Gall, which located 
 in the cerebellum the sexual impulse and instincts, is at the present 
 day generally abandoned; for the reason that it has not been found 
 to be sufficiently supported by anatomical and experimental facts, 
 many of which are indeed directly opposed to it. The opinion 
 which has of late years been received with the most favor is that 
 first advocated by Flourens, which attributes to the cerebellum the 
 power of associating or "co-ordinating" the different voluntary 
 movements. 
 
 It is evident, indeed, that such a power does actually reside in 
 some part of the nervous system. No movements are effected by 
 the independent contraction of single muscles; but always by 
 several muscles acting in harmony with each other. The number 
 and complication of these associated movements vary in different 
 classes of animals. In fish, for example, progression is accom- 
 plished in the simplest possible manner, viz., by the lateral flexion 
 and extension of the vertebral column. In serpents it is much the 
 same. In frogs, lizards, and turtles, on the other hand, the four 
 jointed extremities come into play, and the movements are some- 
 
CEKEBELLUM. 371 
 
 what complicated. They are still more so in birds and quadrupeds; 
 and finally, in the human subject they become both varied and 
 complicated in the highest degree. Even in maintaining the ordi- 
 nary postures of standing and sitting, there are many different mus- 
 cles acting together, in each of which the degree of contraction, in 
 order to preserve the balance of the body, must be accurately pro- 
 portioned to that of the others. In the motions of walking and 
 running, or in the still more delicate movements of the hands and 
 fingers, this harmony of muscular action becomes still more evident, 
 and is seen also to be absolutely indispensable to the efficiency of 
 the muscular apparatus. 
 
 The opinion which locates the above harmonizing or associating 
 power in the cerebellum was first suggested by the effects observed 
 after experimentally injuring or destroying this part of the brain. 
 If the cerebellum be exposed in a living pigeon, and a portion of 
 its substance removed, the animal exhibits at once a peculiar un- 
 certainty in his gait, and in the movement of his wings. If the 
 injury be more extensive, he 'loses altogether the power of flight, 
 and can walk, or even stand, only with great difficulty. This is not 
 owing to any actual paralysis, for the movements of the limbs are 
 exceedingly rapid and energetic; but is due to a peculiar want of 
 control over the muscular contractions, precisely similar to that 
 which is seen in a man in a state of intoxication. The movements 
 of the legs and wings, though forcible and rapid, are confused and 
 blundering; so that the animal cannot direct his steps to any par- 
 ticular spot, nor support himself in the air by flight. He reels and 
 tumbles, but can neither walk nor fly. 
 
 The senses and intelligence at the same time are unimpaired. It 
 is extremely curious, as first remarked by Longet, to compare the 
 different phenomena produced by removal of the cerebrum and by 
 that of the cerebellum. If we do these operations upon two dif- 
 ferent pigeons, and place the animals side by side, it will be seen 
 that the first pigeon, from whom the cerebrum only has been re- 
 moved, remains standing firmly upon his feet, in a condition of 
 complete repose ; and that when aroused and compelled to stir, he 
 moves sluggishly and unwillingly, but acts otherwise in a perfectly 
 natural manner. The second pigeon, on the other hand, from 
 whom the cerebellum only has been taken away, is in a constant 
 state of agitation. He is easily terrified, and endeavors, frequently 
 with violent struggles, to escape the notice of those who are 
 watching him ; but his movements are sprawling and unnatural. 
 
372 THE BRAIN". 
 
 and are evidently no longer under the effectual control of the will, 
 (B'ig. 142.) If the entire cerebellum be destroyed, the animal is 
 no longer capable of assuming or retaining any natural posture. 
 His legs and wings are almost constantly agitated with ineffectual 
 
 Fig. 142. 
 
 PrOEON, AFTER REMOVAL OF THE CeREBELI, CM. 
 
 struggles, which are evidently voluntary in character, but are at 
 the same time altogether irregular and confused. Death generally 
 takes place after this operation within twenty-four hours. 
 
 The results of the above experiment are extremely constant and 
 invariable, and by themselves would lead us to adopt, with a good 
 degree of confidence, the opinion of Flourens. This opinion evi- 
 dently has more direct evidence in its favor than any other theory 
 which has yet been broached with regard to the function of the 
 cerebellum. Many facts derived from comparative anatomy tend, 
 also, to confi.rm the same opinion. If we compare different classes 
 of animals with each other, as fish with reptiles, or birds with quad- 
 rupeds, in which the development and activity of the entire nervous 
 system vary extremely, the results of the comparison will be often 
 contradictory; but if we compare different species belonging to 
 the same class and order, in which the general structure and plan 
 of organization are nearly the same, we often find the development 
 of the cerebellum to correspond very closely with the perfection 
 and variety of the muscular movements. The frog, for example, 
 is an aquatic reptile provided with anterior and posterior extremi- 
 ties ; but its movements, though rapid and vigorous, are exceed- 
 ingly simple in character, consisting of little else than flexion and 
 
TUBERCULA QUADRIGEMINA. 373 
 
 extension of the posterior limbs. The cerebellum in this animal 
 is exceedingly small, compared with the rest of the brain ; being 
 nothing more than a thin, narrow ribbon of nervous matter, 
 stretched across the upper part of the fourth ventricle. In the 
 common turtle we have another aquatic reptile, where the move- 
 ments of swimming, diving, progression, &c., are accomplished by 
 the consentaneous action of both anterior and posterior extremities, 
 and where tbe motions of the head and neck are also mucb more 
 varied than in the frog. In this instance the cerebellum is very 
 much more highly developed than in the former. In the alli- 
 gator, again, a reptile whose motions, both of the head, limbs, 
 and tail, approach very closely to those of the quadrupeds, the 
 cerebellum is still larger in proportion to the remaining ganglia of 
 the encephalon. 
 
 In the above instances, therefore, an evident correspondence 
 exists between the size of the cerebellum and the variety of move- 
 ment of which the animal is capable. Still, this part of the subject 
 has not yet been sufficiently investigated to enable us to say that 
 such a correspondence exists in all cases. Morbid alterations of 
 the cerebellum, furthermore, such as inflammations, abscess, tu- 
 mors, &c., have not always been found to produce, in the human 
 subject, symptoms connected with a loss of harmony in the volun- 
 tary movements. The complete function of the cerebellum., ac- 
 cordingly, cannot yet be regarded as positively ascertained ; but so 
 far as we may rely on the results of direct experiment, and on the 
 general facts of comparative anatomy, the most plausible opinion is 
 that of Flourens, viz., that the cerebellum possesses the power of 
 uniting and harmonizing the action of separate muscles, so that 
 they may assist each other in the production of varied and com- 
 plicated movements. 
 
 TUBERCULA QUADRIGEMINA. 
 
 These bodies, notwithstanding their small size, are very important 
 in regard to their function. They give origin to the optic nerves, 
 and preside, as ganglia, over the sense of sight; on which account 
 they are also known by the name of the " optic ganglia." Their 
 development corresponds very closely with that of the external 
 organs of vision. Thus, they are large in fish, reptiles, and birds, 
 in which the eyeball is for the most part very large in proportion 
 
874 • THE BEAIN". 
 
 to the entire head ; and are small in quadrupeds and in man, 
 where the eyeball is, comparatively speaking, of insignificant size. 
 Direct experiment also shows the close connection between the 
 tubercula quadrigemina and the sense of sight. Section of the 
 optic nerve at any point between the retina and the tubercles, pro- 
 duces complete blindness; and destruction of the tubercles them- 
 selves has the same effect. But if the division be made between 
 the tubercles and the cerebrum, or if the cerebrum itself be taken 
 away while the tubercles are left untouched, vision, as we have 
 already seen, still remains. It is the tubercles, therefore, in which 
 the impression of light is perceived. So long as these ganglia are 
 uninjured and retain their connection with the eye, vision remains. 
 As soon as this connection is cut off, or the ganglia themselves are 
 injured, the power of vision is destroyed. 
 
 The tubercula quadrigemina not only serve as nervous centres 
 for the perception of light, but a reflex action also takes place 
 through them, by which the quantity of light admitted to the eye 
 is regulated to suit the sensibility of the pupil. In darkness and 
 in twilight, or wherever the light is obscure and feeble, the pupil 
 is enlarged by a relaxation of its circular fibres, so as to admit as 
 large a quantity of light as possible. On first coming into a dark 
 room, accordingly, everything is nearly invisible ; but gradually, 
 aS the pupil dilates and as more light is admitted, objects begin to 
 show themselves with greater distinctness, and at last we can see 
 tolerably well in a place where we were at first unable to perceive 
 a single object. On the other hand, when the eye is exposed to 
 an unusually brilliant light, the pupil contracts and shuts out so 
 much of it as would be injurious to the retina. 
 
 The above is a reflex action, in which the impression received by 
 the retina is transmitted along the optic nerve to the tubercula 
 quadrigemina. From the tubercles, a motor impulse is then sent 
 out through the motor nerves of the eye and the filaments dis- 
 tributed to the iris, and a contraction of the pupil takes place in 
 consequence. The optic nerves act here as sensitive fibres, which 
 convey the impression from the retina to the ganglion; and if 
 they be irritated in any part of their course with the point of a 
 needle, the result is a contraction of the pupil. This influence is 
 not communicated directly from the nerve to the iris, but is first 
 sent inward to the tubercles, to be afterward reflected outward by 
 the motor nerves. So long as the eyeball remains in connection 
 with the brain, mechanical irritation of the optic nerve, as we have 
 
TUBEKCULA QUADRIGEMINA. 
 
 375 
 
 shown above, causes contraction of the pupil; but if the nerve be 
 divided, and the extremity which remains in connection with the 
 eyeball subjected to irritation, no effect upon the pupil is produced. 
 The anatomical arrangement of the optic nerves, and the connec- 
 tions of the optic tubercles, are modified in a remarkable degree in 
 different animals, to correspond with the position of the two eyes. 
 In fish, for example, the eyes are so placed, on opposite sides of the 
 head, that their axes cannot be brought into parallelism with each 
 other, and the two eyes can never be directed together to the same 
 object. In these animals, the optic nerves cross each other at the 
 base of the brain without any intermixture of their fibres; that 
 from the right optic tubercle passing to the left eye, and that from 
 the left optic tubercle passing to the right eye. (Fig. 148.) The two 
 nervous cords are here totally distinct from each other throughout 
 their entire length ; and are only connected, at the point of cross- 
 ing, by intervening areolar tissue. Impressions made on the right 
 eye must therefore be perceived on the left side of the brain; while 
 those which enter the left eye are conveyed to the right side of 
 the brain. 
 
 Fig. 143. 
 
 Fig. 144. 
 
 Inferior Surface of Brain 
 OF Cod. — 1. Eight optic nerve. 2. Left 
 optic nerve. 3. Right optic tubercle. 4. 
 Left optic tubercle. 6, 6. Hemispheres. 
 7. Medulla oblongata. 
 
 Infkrior Surface of Brain op 
 Fowl. — \. Right optic nerve. 2. Left optic 
 nerre 3. Right optic tubercle. 4. Left 
 optic tubercle. 6, 6. Hemispheres. 7. Me- 
 dulla oblongata. 
 
 In birds, also, the axes of the two eyes are so widely divergent 
 that an object cannot be distinctly in focus for both of them at the 
 
376 
 
 THE BRAIlSr. 
 
 same time. The optic nerves are here united, and apparently sol- 
 dered together, at their point of crossing; but the decussation of 
 their fibres is nevertheless complete. (Fig. 144.) The nervous fila- 
 ments coming from the left side pass altogether over to the right ; 
 and those coming from the right side pass over to the left. The 
 result of direct experiment on the crossed action of the tubercles 
 in these animals corresponds with the anatomical arrangement of 
 the nervous fibres. If one of the optic tubercles be destroyed in 
 the pigeon, complete blindness is at once produced in the eye of 
 the opposite side; but vision remains unimpaired in the eye of the 
 same side with the injury. 
 
 In the human subject, on the other hand, where the visual axes 
 are parallel, and where both eyes are simultaneously directed to the 
 same object, the optic nerves decussate with each other in such a 
 manner as to form a connection between the two opposite sides, as 
 well as between each tubercle and retina of the same side. (Fig. 
 145.) This decussation, which is somewhat complicated, takes place 
 
 Fig. 145. 
 
 CotTRSE OP Optic Nerves in Man. — 1, 2. Eight and left eyeballs. 3. Decussation of optic 
 nerves. 4, i. Tubercula quadrigemina. 
 
 in the following manner. From each optic tubercle three difi'erent 
 bundles or " tracts" of nervous fibres are given ofi". One set passes 
 
TUBER ANNULARE. 377 
 
 across transversely at the point of decussation, and turning back- 
 ward, terminates in the tubercle of the opposite side; another, cross 
 ing diagonally, continues onward to the opposite eyeball; while a 
 third passes directly forward to the eyeball of the same side. A 
 fourth set of fibres, still, passes across, in front of the decussation, 
 from the retina of one eye to that of the opposite side. We have, 
 therefore, by this arrangement, the two retinae, as well as the two 
 optic tubercles, connected with each other by commissural fibres ; 
 while each tubercle is, at the same time, connected both with its 
 own retina and with that of the opposite side. It is undoubtedly 
 owing to these connections that when, in the human subject, the eyes 
 are directed in their proper axes, the two retinae, as well as the two 
 optic tubercles, act as a single organ. Vision is single, therefore, 
 though there are two images upon the retinae. Double vision 
 occurs only when the eyeballs are turned out of their proper direc- 
 tion, so that the parallelism of their axes is lost, and the image no 
 longer falls upon corresponding parts of the two retinae. 
 
 TUBER ANNULARE. 
 
 The collection of gray matter imbedded in the deeper portions 
 of the tuber annulare occupies a situation near the central part of 
 the brain, and lies directly in the course of the ascending fibres of 
 the anterior and posterior columns of the cord. This ganglion is 
 immediately connected with the functions of sensation and volun- 
 tary motion. We have already seen that these functions are not 
 destroyed by taking away the cerebrum, and that they also remain 
 after removal of the cerebellum. According to the experiments of 
 Longet, even after complete removal of the olfactory ganglia, the 
 cerebrum, cerebellum, optic tubercles, corpora striata and optic 
 thalami, and when nothing remains in the cavity of the cranium but 
 the tuber annulare and the medulla oblongata, the animal is still 
 sensitive to external impressions, and will still endeavor by volun- 
 tary movements to escape from a painful irritation. The same 
 observer has found, however, that as soon as the ganglion of the 
 tuber annulare is broken up, all manifestations of sensation and 
 volition cease, and even consciousness no longer appears to exist. 
 The only movements which then follow external irritation are the 
 occasional convulsive motions which are due to reflex action of the 
 spinal cord, and which may be readily distinguished from those of a 
 
378 THE BRAIN. 
 
 voluntary character. The animal, under these circumstances, is to 
 all appearances reduced to the condition of a dead body, except for 
 the movements of respiration and circulation, which still go on for 
 a certain time. The tuber annulare must therefore be regarded as 
 the ganglion by which impressions, conveyed inward through the 
 nerves, are first converted into conscious sensations; and in which 
 the voluntary impulses originate, which stimulate the muscles to 
 contraction. 
 
 We must carefully distinguish, however, in this respect, a simple 
 sensation from the ideas to which it gives origin in the mind, and 
 the mere act of volition from the train of thought which leads to 
 it. Both these purely mental operations take place, as we have 
 seen, in the cerebrum ; for mere sensation and volition may exist 
 independently of any intellectual action, as they may exist after 
 the cerebrum has been destroyed. A sensation may be felt, for 
 example, without our having the power of thoroughly appreciating 
 it, or of referring it to its proper source. This condition is often 
 experienced in a state of deep sleep, when, the body being exposed 
 to cold, or accidentally placed in a constrained position, we feel a 
 sense of suffering, without being able to understand its cause. We 
 may even, under such circumstances, execute voluntary movements 
 to escape the cause of annoyance ; but these movements, not being 
 directed by any active intelligence, fail of accomplishing their ob- 
 ject. We therefore remain in a state of discomfort until, on awak- 
 ening, the activity of the reason and judgment is restored, when 
 the offending cause is at once removed. 
 
 We distinguish, then, between the simple power of sensation, 
 and the power of fully appreciating a sensitive impression and of 
 drawing a conclusion from it. We distinguish also between the 
 intellectual process which leads us to decide upon a voluntary 
 movement, and the act of volition itself. The former must precede, 
 the latter must follow. The former takes place, so far as experi- 
 ment can show, in tlie cerebral hemispheres ; the latter, in the gan- 
 glion of the tuber annulare. 
 
 MEDULLA OBLONGATA. 
 
 The last remaining ganglion of the encephalon is that of the 
 medulla oblongata. This ganglion, it will be remembered, is 
 imbedded in the substance of the restiform body, occupying the 
 
MEDULLA OBLONGATA. 379 
 
 lateral and posterior portions of the medulla, at the point of origin 
 of the pneumogastric nerves. This portion of the brain has long 
 been known to be particularly essential to the preservation of life ; 
 so that it has received the name of the " vital point," or the 
 " vital knot." All the other parts of the brain may be injured or 
 removed, as we have already seen, without the immediate and ne- 
 cessary destruction of life ; but so soon as the medulla oblongata is 
 broken up, and its ganglion destroyed, respiration ceases instanta- 
 neously, and the circulation also soon comes to an end. Removal 
 of the medulla oblongata produces, therefore, as its immediate and 
 direct result, a stoppage of respiration; and death takes place prin- 
 cipally as a consequence of this fact. 
 
 Flourens and Longet have determined, with considerable accu- 
 racy, the precise limits of this vital spot in the medulla oblongata. 
 Flourens ascertained that in rabbits it extended from just above 
 the origin of the pneumogastric nerve, to a level situated three lines 
 and a half below this origin. In larger animals, its extent is pro- 
 portionately increased. Longet ascertained, furthermore, that the 
 properties of the medulla were not the same throughout its entire 
 thickness ; but that its posterior and anterior parts might be de- 
 stroyed with comparative impunity, the peculiarly vital spot being 
 confined to the intermediate portions. This vital point accordingly 
 is situated in the layer of gray matter, imbedded in the thickness 
 of the restiform bodies, which has been previously spoken of as 
 giving origin to the pneumogastric nerves. 
 
 The precise nature of the connection between this ganglion and 
 the function of respiration may be described as follows. The 
 movements of respiration, which follow each other with incessant 
 regularity through the whole period of life, are not voluntary 
 movements. We may, to a certain extent, hasten or retard them 
 at will, but our power over them, even in this respect, is extremely 
 limited; and in point of fact they are performed, during the greater 
 part of the time, in a perfectly quiet and regular manner, without 
 our volition and even without our consciousness. They continue 
 uninterrupted through the deepest slumber, and even in a condition 
 of insensibility from accident or disease. 
 
 These movements are the result of a reflex action taking place 
 through the medulla oblongata. The impression which gives rise 
 to them originates principally in the lungs, from the accumulation 
 of carbonic acid in the pulmonary vessels and air-cells, is trans- 
 mitted by the pneumogastric nerves to the medulla, and is thence 
 
380 THE BRAIISr. 
 
 reflected back along the motor nerves to the respiratory muscles. 
 These muscles are then called into action, producing an expansion 
 of the chest. The impression so conveyed to the medulla is usually 
 unperceived by the consciousness. It is generally converted directly 
 into a motor impulse, without attracting our attention or giving 
 rise to any conscious sensation. Respiration, accordingly, goes on 
 perfectly well without our interference and without our knowledge. 
 The nervous impression, however, conveyed to the medulla, though 
 usually imperceptible, may be made evident at any time by volun- 
 tarily suspending the respiration. As the carbonic acid begins to 
 accumulate in the blood and in the lungs, a peculiar sensation makes 
 itself felt, which grows stronger and stronger with every moment, 
 and impels us to recommence the movements of inspiration. This 
 peculiar sensation, entirely different in character from any other, is 
 desio'nated by the French under the name of " besoin de respirer." 
 It becomes more urgent and distressing, the longer respiration is 
 suspended, until finally the impulse to expand the chest can no 
 longer be resisted by any effort of the will. 
 
 During ordinary respiration, therefore, each inspiratory move- 
 ment is excited by the partial vitiation of the air contained in the 
 lungs. As soon as a new supply has been inhaled, the impulse to 
 respire is satisfied, the muscles relax, and the chest collapses. In 
 a few seconds the previous condition recurs and the same move- 
 ments are repeated, producing in this way a regular alternation of 
 inspirations and expirations. 
 
 Since the movements of respiration are performed partly by the 
 diaphragm and partly by the intercostal muscles, they will be 
 differently modified by injuries of the nervous system, according to 
 the spot at which the injury is inflicted. If the spinal cord, for 
 example, be divided or compressed in the lower part of the neck, 
 all the intercostal muscles will be necessarily paralyzed, and respi- 
 ration will then be performed entirely by the diaphragm. The 
 chest in these cases remaining motionless, and the abdomen alone 
 rising and falling with the movements of the diaphragm, such 
 respiration is called " abdominal" or " diaphragmatic" respiration. 
 It is a common symptom of fracture of the spine in the lower 
 cervical region. If the phrenic nerve, on the other hand, be 
 divided, the diaphragm will be paralyzed, and respiration will then 
 be performed altogether by the rising and falling of the ribs. It 
 is then called "thoracic" or "costal" respiration. If the injury 
 inflicted upon the spinal cord be above the origin of the second 
 
MEDULLA OBLONGATA. 381 
 
 and third cervical nerves, both the phrenic and intercostal nerves 
 are at once paralyzed, and death necessarily takes place from suf; 
 focation. The attempt at respiration, however, still continues in 
 these cases, showing itself by ineffectaal inspiratory movements of 
 the mouth and nostrils. Finally, if the medulla itself be broken 
 up by a steel instrument introduced through the foramen magnum, 
 so as to destroy the nervous centre in which the above reflex action 
 takes place, both the power and the desire to breathe are at once 
 taken away. No attempt is made at inspiration, there is no 
 struggle, and no appearance of suffering. The animal dies simply 
 by a want of aeration of the blood, which leads in a few moments 
 to an arrest of the circulation. 
 
 It is owing to the above action of the medulla oblongata that in- 
 juries of this part are so promptly and constantly fatal. When the 
 " neck is broken," as in hanging or by sudden falls upon the head, a 
 rupture takes place of the transverse ligament of the atlas; the head, 
 together with the first cervical vertebra, is allowed to slide forward, 
 and the medulla is compressed between the odontoid process of the 
 axis in front and the posterior part of the arch of the atlas behind. 
 In cases of apoplexy, where any part of the hemispheres, corpora 
 striata, or optic thalami, is the seat of the hemorrhage, the patient 
 generally lives at least twelve hours ; but if the hemorrhage take 
 place into the medulla itself, or at the base of the brain in its imme- 
 diate neighborhood, so as to compress its substance, death follows 
 instantaneously, and by the same mechanism as where the medulla 
 is intentionally destroyed. 
 
 An irregularity or want of correspondence in the movements of 
 respiration is accordingly found to be one of the most threatening 
 of all symptoms in affections of the brain. A disturbance or sus- 
 pension of the intellectual powers does not indicate necessarily any 
 immediate danger to life. Even sensation and volition may be im- 
 paired without serious and direct injury to the organic functions. 
 These symptoms only indicate the threatening progress of the dis- 
 ease, and show that it is gradually approaching the vital centre. It 
 is common to see, however, as the medulla itself begins to be impli- 
 cated, a paralysis first showing itself in the respiratory movements 
 of the nostrils and lips, while those of the chest and abdomen still 
 go on as usual. The cheeks are then drawn in with every inspira- 
 tion and puffed out sluggishly with every expiration, the nostrils 
 themselves sometimes participating in these unnatural movements. 
 A still more threatening symptom, and one which frequently pre- 
 
382 THE BEAIN. 
 
 cedes death, is an irregular, hesitating respiration, which sometimes 
 attracts the attention of the physician, even before the remaining 
 cerebral functions are seriously impaired. These phenomena de- 
 pend on the connection between the respiratory movements and the 
 reflex action of the medulla oblongata. 
 
 We have now, in studying the functions of various parts of the 
 cerebro-spinal system, become familiar with three difl'erent kinds of 
 reflex action. 
 
 The first is that of the spinal cord. Here, there is no proper 
 sensation and no direct consciousness of the act which is performed. 
 It is simply a nervous impression, coming from the integument, 
 and transformed by the gray matter of the spinal cord into a motor 
 impulse destined for the muscles. This action will take place after 
 the removal of the hemispheres and the abolition of consciousness, 
 as well as in the ordinary condition. The respiratory action of the 
 medulla oblongata is of the same general character ; that is, it is 
 not necessarily connected with either volition or consciousness. 
 The only peculiarity in this instance is that the original nervous 
 impression is of a special character, and its influence is finally 
 exerted upon a special muscular apparatus. Actions of this nature 
 are termed, par excellence, reflex actions. 
 
 The second kind of reflex action takes place in the tuber annu- 
 lare. Here the nervous impression, which is conveyed inward 
 from the integument, instead of stopping,at the spinal cord, passes 
 onward to the tuber annulare, where it first gives rise to a con- 
 scious sensation ; and this sensation is immediately followed by a 
 voluntary act. Thus, if a crumb of bread fall into the larynx, the 
 sensation produced by it excites the movement of coughing. The 
 sensations of hunger and thirst excite a desire for food and drink. 
 The sexual impulse acts in precisely the same manner ; the percep- 
 tion of particular objects giving rise immediately to special desires 
 of a sexual character. 
 
 It will be observed, in these instances, that in the first place, 
 the nervous sensation must be actually perceived, in order to pro- 
 duce its effect; and in the second place that the action which 
 follows is wholly voluntary in character. But the most important 
 peculiarity, in this respect, is that the voluntary impulse follows 
 directly upon the receipt of the sensation. There is no intermediate 
 reasoning or intellectual process. We do not cough because we 
 know that this is the most effectual way to clear the larynx ; but 
 simply because we are impelled to do so by the sensation which is 
 
MEDULLA OBLONGATA. 383 
 
 felt at the time. We do not take food or drink because we know- 
 that they are necessary to support life, much less because we under- 
 stand the mode in which they accomplish this object ; but merely 
 because we desire them whenever we feel the sensations of hunger 
 and thirst. 
 
 All actions of this nature are termed insiinctive. They are volun- 
 tary in character, but are performed blindly ; that is, without any 
 idea of the ultimate object to be accomplished by them, and simply 
 in consequence of the receipt of a particular sensation. Accord- 
 ingly experience, judgment, and adaptation have nothing to do with 
 these actions. Thus the bee builds his cell on the plan of a mathe- 
 matical figure, without performing any mathematical calculation. 
 The silkworm wraps himself in a cocoon of his own spinning, 
 certainly without knowing that it is to afford him shelter during 
 the period of his metamorphosis. The fowl incubates her eggs 
 and keeps them at the proper temperature for development, simply 
 because the sight of them creates in her a desire to do so. The 
 habits of these animals, it is true, are so arranged by nature, that 
 such instinctive actions are always calculated to accomplish an 
 ultimate object. But this calculation is not made by the animal 
 himself, and does not form any part of his mental operations. 
 There is consequently no improvement in the mode of performing 
 such actions, and but little deviation under a variety of circum- 
 stances. 
 
 The third kind of reflex action requires the co-operation of the 
 hemispheres. Here, the nervous impression is not only conveyed 
 to the tuber annulare and converted into a sensation, but, still 
 following upward the course of the fibres to the cerebrum, it there 
 gives rise to a special train of ideas. We understand then the 
 external source of the sensation, the manner in which it is calcu- 
 lated to affect us, and how by our actions we may turn it to our 
 advantage or otherwise. The action which follows, therefore, in 
 these cases, is not simply voluntary, but reasonable. It does not 
 depend directly upon the external sensation, but upon an intellec- 
 tual process which intervenes between the sensation and the voli- 
 tion. These actions are distinguished, accordingly, by a character 
 of definite contrivance, and a conscious adaptation of means to 
 ends ; characteristics which do not belong to any other operations 
 of the nervous system. 
 
 The possession of this kind of intelligence and reasoning power 
 is not confined to the human species. We have already seen that 
 
384: THE BRAIN. 
 
 there are many purely instinctive actions in man, as well as in 
 animals. It is no less true that in the higher animals there is often 
 the same exercise of reasoning power as in man. The degree of 
 this power is much less in them than in him, but its nature is the 
 same. Whenever, in an animal, we see any action performed with 
 the evident intention of accomplishing a particular object, to which 
 it is properly adapted, such an act is plainly the result of reason- 
 ing powers, not essentially different from our own. The establish- 
 ment of sentinels by gregarious animals, to warn the herd of the 
 approach of danger, the recollection of punishment inflicted for a 
 particular action, and the subsequent avoidance or concealment of 
 that action, the teachability of many animals, and their capacity of 
 forming new habits or of improving the old ones, are all instances 
 of the same kind of intellectual power, and are quite different from 
 instinct, strictly speaking. It is this faculty which especially pre- 
 dominates over the others in the higher classes of animals, and 
 which finally attains its maximum of development in the human 
 species. 
 
CRANIAL NERVES. 385 
 
 CHAPTER V. 
 
 THE CRANIAL NERVES. 
 
 In examining the cranial nerves, we shall find that although they 
 at first seem quite different in their distribution and properties 
 from the spinal nerves, yet they are in reality arranged for the 
 most part on the same plan, and may be studied in a similar 
 manner. 
 
 At the outset, however, we find that there are three^ of the 
 cranial nerves, commonly so called, which must be arranged in a 
 class by themselves ; since they have no character in common with 
 the other nerves originating either from the brain or the spinal cord. 
 These are the three nerves of special sense; viz., the Olfactory, Optic, 
 and Auditory. They are, properly speaking, not so much nerves 
 as commissures, connecting different parts of the encephalic mass 
 with each other. They are neither sensitive nor motor, in the 
 ordinary meaning of these terms; but are capable of conveying 
 only the special sensation characteristic of the organ with which 
 they are connected. 
 
 Olfactory Nerves. — We have already described the so-called 
 olfactory nerves as being in reality commissures, connecting the 
 olfactory ganglia with the central parts of the brain. The masses 
 situated upon the cribriform plate of the ethmoid bone are com- 
 posed of gray matter; and even the filaments which they send 
 outward to be distributed in the Schneiderian mucous membrane, 
 are gray and gelatinous in their texture, and quite different from 
 the fibres of ordinary nerves. The olfactory nerves are not very 
 well adapted for direct experiment. It is, however, at least certain 
 with regard to them that they serve to convey the special sensation 
 of smell; that their mechanical irritation does not give rise to 
 either pain or convulsions; and that finally their destruction, 
 together with that of the olfactory ganglia, does not occasion any 
 paralysis nor loss of ordinary sensibility. 
 25 
 
386 THE CEANIAL NERVES. 
 
 Optic Nerves. — We have already given some account of these 
 nerves and their decussations, in connection with the history of the 
 tubercula quadrigemina. They consist of rounded bundles of 
 white fibres, running between the tubercles and the retinae. As 
 the retinae themselves are membranous expansions consisting mostly 
 of vesicular or cellular nervous matter, the optic nerves, or "tracts," 
 must be regarded as commissures connecting the retinee with the 
 tubercles. We have also seen that they serve, by some of their 
 fibres, to connect the two retinas with each other, as well as the two 
 tubercles with each other. 
 
 The optic nerves convey only the special impression of light from 
 without inward, and give origin to the reflex action of the optic 
 tubercles, by which the pupil is made to contract. According to 
 Lono-et, the optic nerves are absolutely insensible to pain throughout 
 their entire length. When a galvanic current is passed through 
 the eyeball, or when the retina is touched in operations upon the 
 eye, the irritation has been found to produce the impression of 
 luminous sparks and flashes, instead of an ordinary painful sensation. 
 The impression of colored rings or spots may be easily produced 
 by compressing the eye in particular directions; and a sudden 
 stroke upon the eyeball will often give rise to an apparent dis- 
 charge of brilliant sparks. Division of the optic nerves produces 
 complete blindness, but does not destroy ordinary sensibility in any 
 part of the eye, nor occasion any muscular paralysis. 
 
 Auditory Nerves. — The nervous expansion in the cavity of 
 the internal ear contains, like the retina, vesicles or cells as well as 
 fibres ; and the auditory nerves are therefore to be regarded, like 
 the optic and olfactory, as commissural in their character. They 
 are also, like the preceding, destitute of ordinary sensibility. Ac- 
 cording to Longet, they may be injured or destroyed without giving 
 rise to any sensation of pain. They serve to convey to the brain 
 the special sensation of sound, and seem incapable of transmitting 
 any other. Longet' relates an experiment performed by Volta in 
 which, by passing a galvanic current through the ears, the observer 
 experienced the sensation of an interrupted hissing noise, so long 
 as th.e connection of the wires was maintained. Inflammations 
 within the ear, or in its neighborhood, are often accompanied by 
 the perception of various noises, like the ringing of bells, the 
 
 ' Traite de Physiologic, vol. ii. p. 286. 
 
THE CRANIAL NERVES. o»7 
 
 washing of the waves, the humming of insects; sounds which have 
 no external existence, but which are simulated by the morbid irri- 
 tation of the auditory nerve. 
 
 It is evident from the facts detailed above that the nerves of 
 special sense are neither motor nor sensitive, properly speaking; 
 and that they are distinct in their nature from the ordinary spinal 
 nerves. 
 
 The remainder of the cranial nerves, however, have no such 
 essential peculiarities. Some of them are exclusively motor in 
 character, others exclusively sensitive; while most of them exhibit 
 the two properties to a certain extent, as mixed nerves. They 
 may be conveniently arranged in three pairs, according to the 
 regions in which they are distributed, corresponding very closely 
 with the motor and sensitive roots of the spinal nerves. According 
 to such a plan, the arrangement of the cranial nerves would be as 
 follows : — 
 
 
 Ck 
 
 vxiAL Nerves. 
 
 
 Nerves 
 
 of Special Sense. 
 
 
 1. Olfactory. 
 
 2. Optic. 3. Auditory. 
 
 
 Motor Nerves. 
 
 Distributed to Seasitive Nerves. 
 
 
 Motor oculi com. 
 
 ■ 
 
 
 
 Patheticus 
 
 
 Face. Large root of 5 th 
 
 1st PAIR. • 
 
 Motor oc. externus 
 
 
 
 Small root of 5th pai 
 
 r 
 
 
 
 L Facial 
 
 , 
 
 
 2d PAIR. 
 
 Sublingual 
 
 Tongue. Glosso-pharyngeal 
 
 3d PAIR. 
 
 Spinal accessory 
 
 
 Neck, &c. Pneumogastric. 
 
 The above arrangement of the cranial nerves is not absolutely 
 perfect in all its details. Thus, while the sublingual supplies the 
 muscles of the tongue alone, the glosso-pharyngeal sends part of 
 its sensitive fibres to the tongue and part to the pharynx; and 
 while the large root of the 5th pair is mostly distributed in the 
 face, one of its branches, viz., the gustatory, is distributed to the 
 tongue. Notwithstanding these irregularities, however, the above 
 division of the cranial nerves is in the main correct, and will be 
 found extremely useful as an assistant in the study of their func- 
 tions. 
 
 There is no impropriety, moreover, in regarding all the motor 
 branches distributed upon the face as one nerve; since even the 
 anterior roots of the spinal nerves originate from the spinal cord, 
 each by several distinct filaments, which are associated into a single 
 bundle only at a certain distance from their point of origin. The 
 
388 THE CRANIAL NERVES. 
 
 mere fact that two nerves leave the cavity of the cranium by the 
 same foramen does not indicate that they have the same or even a 
 similar function. Thus the facial and auditory both escape from 
 the cavity of the cranium by the foramen auditorium internum, and 
 yet we do not hesitate to regard them as entirely distinct in their 
 nature and functions. It is the ultimate distribution of a nerve, 
 and not its course through the bones of the skull, that indicates 
 its physiological character and position. For while the ultimate 
 distribution of any particular nerve is always the same, its arrange- 
 ment as to trunks and branches may vary, in different species 
 of animals, with the anatomical arrangement of the bones of the 
 skull. This is well illustrated by a fact first pointed out by Dr. 
 Jeffries Wyman^ in the anatomy of the nervous system of the 
 bullfrog. In this animal, both the facial nerve and motor oculi 
 externus, instead of arising as distinct nerves, are actually given 
 off as branches of the 5th pair ; while their ultimate distribution is 
 the same as in other animals. All the motor and sensitive nerves 
 distributed to the face are accordingly to be regarded as so many 
 different branches of the same trunk; varying sometimes in their 
 course, but always the same in their ultimate distribution. 
 
 MOTOR NERVES. 
 
 The motor nerves of the head are in all respects identical in their 
 properties with the anterior roots of the spinal nerves. For, in 
 the first place, they are distributed to muscles, and not to the 
 inteo-ument or to mucous membranes; secondly, their division 
 causes muscular paralysis; and thirdly, mechanical irritation ap- 
 plied at their origin produces muscular contraction in the parts to 
 which they are distributed, but does not give rise to a painful 
 sensation. In several instances, nevertheless, the motor nerves, 
 though insensible at their origin, show a certain degree of sensibi- 
 lity when irritated after their exit from the skull, owing to fibres 
 of communication which they receive from the purely sensitive 
 nerves. In this respect they resemble the spinal nerves, the motor 
 and sensitive filaments of which are at first distinct in the anterior 
 and posterior roots, but afterward mingle with each other, on 
 leaving the cavity of the spinal canal. 
 
 ' Nervous System of Rana pipiens ; published by the Smithsonian Institution. 
 Washington, 1853. 
 
MOTOR CRANIAL NERVES. 389 
 
 Motor OcuLi Communis. — This nerve, which is sometimes known 
 bj the more convenient name of the oculo-molorius, originates from 
 the inner edge of the eras cerebri, passes into the cavity of the 
 orbit by the sphenoidal fissure, and is distributed to the levator 
 palpebra3 superioris, and to all the muscles moving the eyeball, 
 except the external rectus and the superior oblique. Its irritation 
 accordingly produces convulsive movements in these parts, and 
 its division has the effect of paralyzing the muscles to which it is 
 distributed. The superior eyelid falls down over the pupil, and 
 cannot be raised, owing to the inaction of its levator muscle, so 
 that the eye appears constantly half shut. This condition is known 
 by the name of " ptosis." The movements of the eyeball are also 
 nearly suspended, and permanent external strabismus takes place, 
 owing to the paralysis of the internal rectus muscle, while the ex- 
 ternal rectus, animated by a different nerve, preserves its activity. 
 
 Patheticus. — This nerve, which supplies the superior oblique 
 muscle of the eyeball, is similar in its general properties to the pre- 
 ceding. Its section causes paralysis of the above muscle, without 
 any loss of sensibility. 
 
 Motor Externus. — This nerve, the sixth pair, according to the 
 usual anatomical arrangement, is distributed to the external rectus 
 muscle of the eyeball. Its division or injury by disease is followed 
 by internal strabismus, owing to the unopposed action of the internal 
 rectus muscle. 
 
 Small Root of 5th Pair. — It will be remembered that the 5th 
 pair of nerves arises by two roots, which run in close proximity 
 to each other, as far as the level of the Casserian ganglion. The 
 fibres of the smaller root, however, do not mingle at all with the 
 substance of the ganglion, but pass underneath it, as a distinct bun- 
 dle, and emerge afterward from the skull by the foramen ovale of 
 the sphenoid bone, as a portion of the inferior maxillary branch of 
 the 5th pair. While the remainder of the 5th pair is distributed 
 to the integument and mucous membranes about the face, all the 
 fibres derived from this smaller root are sent to the muscles con- 
 cerned in mastication, viz., the great temporal, the masseter, the 
 internal and external pterygoids, the digastric, and the mylo-hyoid. 
 It is therefore sometimes known as the " masticator" nerve. It is 
 exclusively the motor nerve of these muscles ; for while galvaniza- 
 tion of the large root of the 5th pair, according to Longet, pro- 
 
390 
 
 THE CRANIAL NERVES. 
 
 duces no convulsive movement, but only a painful sensation, if the 
 irritation be applied to the small root alone, the above muscles are 
 immediately thrown into contraction, and the jaws violently brought 
 together. Section of this nerve paralyzes the muscles of mastica- 
 tion, without affecting the other muscles of the face. 
 
 Facial. — This nerve was known to the older anatomists as the 
 " portio dura of the seventh pair." Tt leaves the cavity of the 
 cranium by the internal auditory foramen, in company with the 
 auditory nerve; and as the latter is of a softer consistency than the 
 facial, they have received the names respectively of the "portio 
 mollis" and " portio dura" of the seventh pair. There is, however, 
 no physiological connection between these two nerves; for while 
 the auditory is spread out in the cavity of the internal ear, the facial 
 passes onward through the petrous portion of the temporal bone, 
 emerges at the stylo mastoid foramen, bends round beneath the 
 external ear, and passes forward through the substance of the 
 parotid gland, forming a plexus, called the " pes anserinus," by the 
 abundant inosculation of its branches. Tt then sends its filaments 
 forward in a diverging course, and is finally distributed to the 
 superficial muscles of the face; those, namely, which are concerned 
 in the production of expression. (Fig. 146.) 
 
 The facial, consequently, is the 
 motor nerve of the face. It has no- 
 thing to do with transmitting sen- 
 sitive impressions, since it has been 
 frequently shown that after section 
 of the 5th pair, the facial remaining 
 entire, the sensibility of the face is 
 completely lost; so that the integu- 
 ment may be cut, pricked, burned, 
 or lacerated, without any sign of 
 pain being exhibited by the ani- 
 mal. The facial, therefore, does not 
 transmit sensation from these parts ; 
 and its division, which was formerly 
 resorted to in cases of tic doulou- 
 reux, is accordingly altogether in- 
 capable of relieving neuralgic pains. 
 This nerve is, however, directly connected with muscular action. 
 Mechanical or galvanic irritation of its fibres produces convulsive 
 
 Fig. 146. 
 
 Facial Nerve. 
 
MOTOR CRANIAL NERVES. 391 
 
 twitchiijgs in the nostrils, lips, cheeks, &c. Section of the facial 
 on one side, its destruction by disease, or compression by a tumor, 
 induces the extremely characteristic affection known as "facial 
 paralysis." The affected side of the face in these cases, up to the 
 median line, loses altogether its power of motion, and at the same 
 time its natural expression. The corner of the mouth falls down- 
 ward, and the whole lower part of the face is drawn over to the 
 opposite side by the force of the antagonistic muscles. The lips 
 are unable to retain the fluids of the mouth, and the saliva dribbles 
 away from between them, giving to the face a remarkably vacant 
 and helpless appearance. The lower eyelid also sinks downward 
 from paralysis of the orbicularis muscle, and the eye cannot be 
 completely closed. It will be observed that precisely opposite effects 
 are produced upon the eyelids by paralysis of the oculo-motorius 
 and of the facial. In the former instance, owing to paralysis of the 
 levator palpebrse superioris, the eye is always partially closed ; in 
 the latter, owing to paralysis of the orbicularis, it is always par- 
 tially open. 
 
 Though the facial, however, be essentially a motor nerve, yet its 
 principal branches distributed to the face have a certain degree of 
 sensibility ; that is, when irritated in the middle of their course, the 
 animal immediately gives evidence of a painful sensation. Longet 
 has shown, by an extremely ingenious mode of experiment,^ that 
 this sensibility of the branches of the facial does not depend on 
 any sensitive fibres of its own, but upon those which it derives 
 from inosculation with the fifth pair. He exposes, for example, the 
 facial nerve in the dog, and irritating its principal branches one 
 after the other, at each application of the irritant there are evident 
 signs of pain. He then divides the facial nerve at its point of exit 
 from the stylo-mastoid foramen, and finds that, after this operation, 
 the sensibility of its branches still remains. The fibres, accordingly, 
 upon which this sensibility depends, do not pass out with the trunk 
 of the nerve, but are derived from some other source. The experi- 
 menter, then, upon another animal, divides the 5th pair within the 
 skull, leaving the facial untouched ; and afterward, on irritating as 
 before the exposed branches of the latter nerve, he finds that its 
 sensibility has entirely disappeared. It is by filaments, accordingly, 
 derived from the 5th pair, that a certain degree of sensibility is 
 communicated to the branches of the facial. 
 
 ' Traite de Physiologie, vol. ii. pp. 3.54-3.57. 
 
392 THE CRANIAL NERVES. 
 
 These facts account for the peculiar circumstance that, in cases 
 of tic douloureux, the spasmodic pain sometimes follows exactly the 
 course of the facial nerve, viz : from behind the ear forward upon 
 the side of the face ; and yet the section of this nerve does not put 
 an end to the neuralgia, but only causes paralysis of the facial 
 muscles. 
 
 Sublingual. — The sublingual nerve originates from the anterior 
 and lateral portions of the medulla oblongata, and passing out by 
 the anterior condyloid foramen, is distributed exclusively to the 
 muscles of the tongue. Irritation of its fibres in any part of their 
 course produces convulsive twitching in this organ. Its section 
 paralyzes completely the movements of the tongue, without affecting 
 directly the sensibility of its mucous membrane. If irritated at its 
 origin, the sublingual nerve, according to the experiments of Longet, 
 is entirely insensible ; but if the irritation be applied in the middle 
 of its course, signs of pain are immediately manifested. Its sensi- 
 bility, like that of the facial, is consequently derived from its inos- 
 culating with other sensitive nerves after its emergence from the 
 skull. 
 
 Spinal Accessory. — This nerve originates by many filaments 
 from the side of the medulla oblongata below the level of the pneu- 
 mogastric, and also from the lateral portion of the spinal cord, 
 between the anterior and posterior roots of the upper five or six 
 cervical nerves. Its fibres pass upward, enter the cavity of the cra- 
 nium by the foramen magnum, and again emerge from it by the 
 posterior foramen lacerum, in company with the jugular vein and 
 the glosso-pharyngeal and pneumogastric nerves, to the latter of 
 which it gives off an important branch of communication. It is 
 finally distributed to the sterno-mastoid and trapezius muscles. 
 
 The above muscles, however, are also supplied by branches from 
 the cervical and dorsal nerves ; and consequently, it has been found 
 that division of the spinal accessory is not followed by their com- 
 plete paralysis ; but only by a certain debility, owing to their having 
 lost a part of their motor force. The sterno-mastoid and trapezius 
 serve as accessory muscles of respiration, and come into play when 
 the respiratory movements are unusually hurried or laborious. 
 The spinal accessory was regarded by Sir Charles Bell as especially 
 devoted to this function in the above muscles, and was, therefore^ 
 called, by him, the "superior respiratory nerve." 
 
SENSITIVE CRANIAL NERVES. 393 
 
 The spinal accessory has been found by Bernard to be insensible 
 at its origin, like the anterior roots of the spinal nerves; but if irri- 
 tated after its exit from the skull, it gives signs of sensibility. This 
 may be attributed to its receiving filaments of inosculation from the 
 anterior branches of the first and second cervical nerves. The rea- 
 son for the above anatomical fact, viz., that motor nerves are sup- 
 plied daring their course with sensitive fibres by inosculation, 
 becomes evident when we reflect that the muscles themselves pos- 
 sess a certain degree of sensibility, though less than that which 
 belongs to the integument and to some parts of the mucous mem- 
 branes. This sensibility of the muscles is undoubtedly essential 
 to the perfect performance of their function ; and, as the motor 
 nerves are incapable by themselves of transmitting sensitive im- 
 pressions, they are joined, soon after their origin, by other filaments 
 which communicate to them the necessary power. 
 
 SENSITIVE NERVES. 
 
 The three sensitive nerves originating from the brain are the 
 large root of the 5th pair, the glosso-pharyngeal, and the pneumo- 
 gastric. It will be observed that, in all their essential properties, 
 they correspond with the posterior roots of the spinal nerves. Like 
 them they are inexcitable, but extremely sensitive. Irritated at 
 their point of origin, they give rise to acutely painful sensations, 
 but to no convulsive movements. Secondly, if divided at the same 
 situation, the operation is followed by loss of sensibility in the 
 parts to which they are distributed, without any disturbance of the 
 motive power. Each of these nerves, furthermore, like the poste- 
 rior root of a spinal nerve, is provided with a ganglion through 
 which its fibres pass : the 5th pair, with the Casserian ganglion, 
 situated near the inner extremity of the petrous portion of the tem- 
 poral bone ; the glosso-pharyngeal, with the ganglion of Andersch, 
 situated in the jugular fossa; while the pneumogastric presents, 
 just before its passage through the jugular foramen, a ganglion 
 known as the ganglion of the pneumogastric nerve. Finally, the 
 sensitive fibres of all these nerves, beyond the situation of their 
 ganglia, are intermingled with others of a motor origin. The large 
 root of the 5th pair, wbich is exclusively sensitive, is accompanied 
 by the fibres of the small root, which are exclusively motor. The 
 glosso-pharyngeal receives motor filaments from the facial and spinal 
 
394 THE CRANIAL NERVES. 
 
 accessory, becoming consequently a mixed nerve outside the cra- 
 nial cavity; while the pneumogastric is joined by fibres from the 
 spinal accessory and various other nerves of a motor character. 
 These nerves, accordingly, are exclusively sensitive only at their 
 point of origin. Though they afterward retain the predominating 
 character of sensitive nerves, they are yet found, if irritated in the 
 middle of their course, to be intermingled with motor fibres, and 
 to have consequently acquired, to a certain extent, the character 
 of mixed nerves. 
 
 The resemblance, therefore, between the cranial and spinal nerves 
 is complete. 
 
 Fifth Pair. — This is one of the most important and remarkable 
 in its properties of all the cranial nerves. It is the sensitive nerve 
 of the face, and of the adjoining mucous membranes. We have 
 already described the course and distribution of the small root 
 of this nerve. The large root, after emerging from the outer and 
 under surface of the pons Varolii, passes forward over the inner 
 extremity of the petrous portion of the temporal bone. It there 
 expands into a crescentic-shaped swelling, containing a quantity of 
 gray matter with which its fibres are intermingled, and which is 
 known as the Casserian ganglion. The fibres of the smaller root, 
 as already remarked, do not take any part in the formation of this 
 ganglion, but may be seen passing beneath it as a distinct bundle, 
 and continuing their course forward to the foramen ovale, through 
 which they emerge from the skull. From the anterior and external 
 border of the Casserian ganglion, the sensitive portion of the nerve 
 emerges in three separate branches, viz., the ophthalmic, the su- 
 perior maxillary, and the inferior maxillary. The first of these, 
 viz., the ophthalmic, is so called because it passes through the 
 orbit of the eye. It enters the sphenoidal fissure, and runs along 
 the upper portion of the orbit, sending branches to the ophthalmic 
 ganglion of the sympathetic, to the lachrymal gland, the conjunc- 
 tiva, and the mucous membrane of the lachrymal sac. It also sends 
 off a small branch (nasal branch) which penetrates into the nasal 
 passages and supplies the Schneiderian mucous membrane. It then 
 emerges upon the face by the supra-orbital foramen, and is dis- 
 tributed to the integument of the forehead and side of the head as 
 far back as the vertex. 
 
 The second branch of this nerve, or the superior maxillary, passes 
 out by the foramen rotund um, and runs along the longitudinal canal 
 
SENSITIVE NERVES. 
 
 395 
 
 Fis. 147. 
 
 Distribution of Fifth Nerve 
 UPON T H !•; F A c R . — n. Casserian ganglion. 
 1. Ophtlialmic branch. 2. Superior maxil- 
 lary branch. 3. Inferior maxillary branch. 
 
 in the floor of the orbit, giving oft' branches during its passage 
 to the teeth of the upper jaw and to the mucous membrane of 
 the antrum maxiHare. It finally 
 emerges upon the middle of the 
 face by the infra-orbital foramen, 
 and is distributed to the lower eye- 
 lid, the nose, the cheek and the 
 upper lip. 
 
 The third, or inferior maxillary 
 branch of the fifth pair, leaves the 
 cavity of the cranium by the fora- 
 men ovale. It first sends off" a few 
 branches to the integument of the 
 temple and external ear, then a 
 large and important branch, vi%., 
 the "gustatory" or "lingual" branch, 
 which is distributed to the mucous 
 membrane of the anterior two-thirds 
 of the tongue. The main trunk 
 then enters the inferior dental canal, 
 sends nerves to the teeth of the 
 
 lower jaw, emerges at the mental foramen, and is finally distributed 
 to the integument of the chin, lower lip, and inferior part of the face. 
 
 This nerve is accordingly distributed to the sensitive surfaces, 
 that is, the integument and mucous membranes, about the face. 
 A few of its fibres are sent also to the muscles of the face ; but 
 these fibres are sensitive in their character, and serve merely 
 to impart to the muscles a certain degree of sensibility. It has 
 been ascertained by Longet that if the ganglionic portion of this 
 nerve be irritated by a galvanic current, no convulsive movements 
 whatever are produced, even in those muscles which are supplied 
 with filaments from its infra-orbital and mental branches; but if 
 its smaller or non-ganglionic root be irritated in the same way, 
 contractions instantly follow in the muscles of mastication. 
 
 Irritation of the 5th pair, in any part of its course, as well as of 
 its larger root behind the Casserian ganglion, produces intense pain. 
 Its division is followed by complete loss of sensibility in the in- 
 tegument of the face, the lips, the conjunctiva, and mucous mem- 
 brane of the nares and mouth. The sense of taste is also destroyed 
 throughout the anterior two-thirds of the tongue, owing to the 
 paralysis of the lingual or gustatory nerve. The skin of the face 
 
396 THE CRANIAL XERVES. 
 
 may then be pricked, burned, cut or lacerated in any way, without 
 producing pain, and even apparently without the knowledge of the 
 animal upon whom the operation is performed. 
 
 The 5th pair, beside supplying the sensibility of the integument 
 of the face, has a peculiar and important influence on the organs 
 of special sense. This influence appears to consist in some connec- 
 tion between the action of the 5th pair and the processes of nutrition; 
 so that when the former is injured, the latter become immediately 
 deranged. For the perfect action of any one of the organs of 
 special sense, two conditions are necessary : first, the sensibility of 
 the special nerve belonging to it, and, secondly, the integrity of the 
 component parts of the organ itself. Xow as the nutrition of the 
 organ is, to a certain extent, under the control of the 5th pair, any 
 serious injury to this nerve produces a derangement in the tissues 
 of the organ, and consequently interferes with the due performance 
 of its function. 
 
 The mucous membrane of the nasal passages, for example, is 
 supplied by two different nerves; first, the olfactory, distributed 
 throughout its upper portion, by which it is endowed with the 
 special sense of smell ; and, secondly, the nasal branch of the 5th 
 pair, distributed throughout its middle and lower portions, by 
 which it is supplied with ordinary sensibility. Although the 
 Schneiderian mucous membrane, therefore, after destruction of the 
 olfactory nerve, loses altogether its power of distinguisMng odors, 
 properly so called, such as the odor of flowers, of turpentine, of 
 sulphuretted hydrogen, and the like, it still remains sensitive to 
 the action of vapors which are merely irritating in their character, 
 such as those of ammonia and acetic acid. These substances act by 
 exciting the ordinary sensibility of the mucous membrane, which is 
 supplied by fibres of the 5th pair. They will also act in a similar 
 manner upon the integument, or upon other mucous membranes 
 endowed with general sensibility ; while true odors are perceptible 
 by the olfactory organ alone. 
 
 The 5th pair accordingly supplies general sensibilit}' to the nasal 
 passages, and this property will remain after the special sense of 
 smell has been destroyed. If, however, the 5th pair itself be 
 divided, not only is general sensibility destroyed in the Schneider- 
 ian mucous membrane, but, according to the experiments of Longet, 
 a disturbance begins to take place in the nutrition of its tissue, 
 by which it is gradually rendered unfit for the performance of 
 its special function, and the power of smell is finally lost. The 
 
SENSITIVE CRANIAL NERVES. 397 
 
 mucous membrane, under these circumstances, becomes injected 
 and swollen, assumes a fungous consistency, and is liable to bleed 
 at the slightest touch. The effect of this alteration is to blunt or 
 altogether destroy the sense of smell. It is owing to a similar 
 unnatural condition of the mucous membrane that the power of 
 smell is always more or less impaired in cases of coryza and 
 influenza. The olfactory nerves become inactive in consequence of 
 the morbid alteration in their mucous membrane, and in the secre- 
 tions which cover it. 
 
 The influence of this nerve over the organ of vision is still more 
 remarkable. It has been known for many years that division of 
 the 5th pair within the cranium, or of its ophthalmic branch, is fol- 
 lowed by an inflammation of the corresponding eye which usually 
 goes on to complete and permanent destruction of the organ. 
 Immediately after the operation, the pupil becomes contracted and 
 the conjunctiva loses its sensibility. At the end of twenty-four 
 hours, the cornea begins to become opaline, and, by the second 
 day, the conjunctiva is already inflamed and begins to discharge a 
 purulent secretion. The inflammation, after commencing in the 
 conjunctiva, increases in intensity and soon spreads to the iris, 
 which becomes covered with a layer of inflammatory exudation. 
 The cornea grows constantly more opaque, until it is at last 
 altogether impermeable to light, and vision is consequently sus- 
 pended. Blindness, therefore, does not result in these instances 
 from any direct affection of the optic nerve or of the retina, but is 
 owing simply to opacity of the cornea. Sometimes the diseased 
 action goes on until it results in ulceration of the cornea and dis- 
 charge of the humors of the eye ; sometimes, after the lapse of 
 several days, the inflammatory appearances subside, and the eye is 
 finally restored to its natural condition. 
 
 It has been observed, however, that, although the above conse- 
 quences always follow division of the 5th pair when performed at 
 the level of the Casserian ganglion, or between it and the eyeball, 
 they are either much diminished in intensity or altogether wanting 
 when the division is made at a point posterior to the ganglion. 
 This circumstance has led to the belief that the influence of the 5th 
 pair on the nutrition of the eyeball does not reside in its own 
 proper fibres, but in some filaments of the sympathetic which join 
 the 5th pair at the level of the Casserian ganglion. If the section 
 accordingly be made at this point, or in front of it, the fibres of the 
 sympathetic will be divided with the others, and inflammation of 
 
398 THE CRANIAL NERVES. 
 
 the eye will result; but if the section be made behind the ganglion, 
 the fibres of the sympathetic will escape division, and the injurious 
 effects upon the eye will be wanting. Such is the explanation 
 usually given of the above-mentioned facts; but the question has 
 not as yet been determined in a direct manner. 
 
 Division of the 5th pair destroys also the general sensibility of 
 the external auditory meatus, the lining membrane of which is 
 supplied by its filaments. Inflammation of this membrane and its 
 consequent alterations, it is well known, interfere seriously with 
 the sense of hearing. It is no uncommon occurrence for an 
 accumulation of cerumen to take place after inflammation of this 
 part, so as to block up the canal and produce partial or complete 
 deafness. It has not been ascertained, however, whether division 
 of the 5th pair is usually followed by similar changes in this part. 
 
 The lingual branch of the 5th pair supplies the anterior ex- 
 tremity and middle portion of the tongue both with general sensi- 
 bility and with the power of taste. The sensibility of. the tongue 
 is accordingly provided for by two difi'erent nerves; in its anterior 
 two-thirds, by the lingual branch of the 5th pair ; in its posterior 
 third, by fibres of the glosso-pharyngeal. 
 
 The facial branches of the 5th pair are the ordinary seat of tic 
 douloureux. This affection is not unfrequently confined to either 
 the supra-orbital, the infra-orbital, or the mental branch ; and the 
 pain may be accurately traced in the direction of their diverging 
 fibres. It has already been mentioned that the painful sensations 
 sometimes also follow the course of the facial, owing to some sen- 
 sitive filaments which that nerve receives from the 5th pair. 
 
 Glosso-Pharyngeal. — This nerve originates from the lateral 
 portion of the medulla oblongata, passes outward, and enters the 
 posterior foramen lacerum in company with the pneumogastric and 
 spinal accessory. While in the jugular fossa it presents a gangliform 
 enlargement, called the ganglion of Andersch, below the level of 
 which it receives branches of communication from the facial and the 
 spinal accessory. It then runs downward and forward and is dis- 
 tributed to the mucous membrane of the base of the tongue, pillars 
 of the fauces, soft palate, middle ear, and upper part of the pharynx. 
 It also sends some branches to the constrictors of the pharynx and 
 the neighboring muscles. Longet has found this nerve at its origin 
 to be exclusively sensitive ; but below the level of its ganglion it 
 has been found by various observers to be both sensitive and motor. 
 
PNEUMOGASTRIC NERVE. 399 
 
 owing to the fibres of communication received from the motor nerves 
 mentioned above. Its final distribution is, however, as we have 
 seen, principally to sensitive surfaces. The principal office of this 
 nerve is to impart the sense of taste to those parts of the tongue to 
 which it is distributed. It also presides over the general sensibility 
 of this part of the tongue, as well as of the fauces and pharynx. 
 
 There are certain reflex actions, furthermore, which take place 
 through the medium of the glosso-pharyngeal nerve. After the 
 food has been thoroughly masticated, it is carried, by the move- 
 ments of the tongue and sides of the mouth, through the fauces, 
 and brought in contact with the mucous membrane of the pharynx. 
 This produces an impression which, conveyed to the medulla 
 oblongata by the filaments of the glosso-pharyngeal, excites the 
 muscles of the fauces and pharynx by reflex action. The food is 
 consequently grasped by these muscles, without the concurrence of 
 the will, and the process of deglutition is commenced. This action 
 is not only involuntary, but it will frequently take place even in 
 opposition to the will. The food, once past the isthmus of the fauces, 
 is beyond the control of volition, and cannot be returned except by 
 convulsive action, equally involuntary in its character. 
 
 Natural stimulants, therefore, applied to the mucous membrane 
 of the pharynx, excite deglutition ; unnatural stimulants, applied to 
 the same part, excite vomiting. If the finger be introduced into 
 the fauces and pharynx, or if the mucous membrane of these parts 
 be irritated by prolonged tickling with the end of a feather, the 
 sensation of nausea, conveyed through the glosso-pharyngeal nerve, 
 is sometimes so great as to produce immediate and copious vomit- 
 ing. This method may often be successfully employed in cases of 
 poisoning, when it is desirable to excite vomiting rapidly, and when 
 emetic medicines are not at hand. 
 
 Pneumogastric. — Owing to the numerous connections of the 
 pneumogastric with other nerves, its varied and extensive distribu- 
 tion, and the important character of its functions, this is properly 
 regarded as one of the most remarkable nerves in the whole body. 
 Owing to the wandering course of its fibres, which are distributed 
 to no less than four different vital organs, viz., the heart, lungs, 
 stomach, and liver, as well as to several other parts of secondary 
 importance, it has been often known by the name of the jmr vagum. 
 The pneumogastric arises, by a number of separate filaments, from 
 the lateral portion of the medulla oblongata, in the groove between 
 
400 
 
 THE CRANIAL NERVES. 
 
 the olivary and restiform bodies. These filaments unite into a 
 single trunk, which emerges from the cranium by the jugular fora- 
 men, where it is provided with a longitudinal ganglionic swelling, 
 the "ganglion of the pneuraogastric nerve." Immediately below 
 the level of this ganglion the nerve receives an important branch 
 
 of communication from the spinal acces- 
 sory, and afterward from the facial, the 
 sublingual, and the anterior branches of 
 the first and second cervicals. 
 
 At its origin, the pneumogastric is ex- 
 clusively a sensitive nerve. Irritated 
 above the situation of its ganglion, it has 
 been found to convey painful sensations 
 alone ; but if the irritation be applied at 
 a lower level, it causes at the same time 
 muscular contractions, owing to the fila- 
 ments which it has received from the 
 above mentioned motor nerves. It be- 
 comes, consequently, after emerging from 
 the cranial cavity, a mixed nerve; and 
 has accordingly, in nearly all its branches, 
 a double distribution, viz., to the mucous 
 membranes and the muscular coat of the 
 organs to which it belongs. 
 
 In passing down the neck this nerve 
 sends branches to the mucous membranes 
 and muscular coat of the pharynx, oeso- 
 phagus, and respiratory passages. Among 
 the most important of these are the two 
 laryngeal nerves, viz., the superior and 
 inferior. The superior laryngeal nerve, 
 which is given off" from the trunk of the 
 pneumogastric just after it has emerged 
 from the cavity of the skull, passes down- 
 ward and forward, penetrates the larynx 
 by an opening in the side of the thyro- 
 hyoid membrane, and is distributed to the 
 raucous membrane of the larynx and glottis, and also to a single 
 laryngeal muscle, viz., the crico-thyroid. This branch is therefore 
 partly muscular, but mostly sensitive in its distribution. The infe- 
 rior laryngeal branch is given off just after the pneumogastric has 
 
 Diagram of Pneumogastric 
 N E B V E, with its principal branches. 
 — ^1. Pharyngeal branch. 2. Supe- 
 rior laryngeal. 3. Inferior laryn- 
 geal. 4. Pulmonary branches. 5. 
 Stomach. 6. Liver. 
 
PNEUMOGASTRIC. 401 
 
 entered the cavity of the chest. It curves round the subclavian 
 artery on the right side and the arch of the aorta on the left, and 
 ascends in the groove between the trachea and oesophagus, to the 
 larynx. It then enters the larynx between the cricoid cartilage and 
 the posterior edge of the thyroid, and is distributed to all the mus- 
 cles of the larynx, with the exception of the crico-thyroid. This 
 branch is, therefore, exclusively muscular in its distribution. 
 
 The trunk of the pneumogastric, after supplying the above 
 branches, as well as sending numerous filaments in the neck to the 
 trachea and oesophagus, gives off in the chest its pulmonary 
 branches, which follow the bronchial tubes in the lungs to their 
 minutest ramifications. It then passes into the abdomen and sup- 
 plies the muscular and mucous layers of the stomach, ramifying 
 over both the anterior and posterior surfaces of the organ; after 
 which its fibres spread out and are distributed to the liver, spleen, 
 pancreas, and gall-bladder. 
 
 The functions of the pneumogastric will now be successively 
 studied in the various organs to which it is distributed. 
 
 Pharynx and (Esophagus. — The reflex action of deglutition, 
 which has already been described as commencing in the upper 
 part of the pharynx, by means of the glosso-pharyngeal, is con- 
 tinued in the lower portion of the pharynx and throughout the 
 oesophagus by the pneumogastric. As the food is compressed by 
 the superior constrictor muscle of the pharynx and forced down- 
 ward, it excites the mucous membrane with which it is brought in 
 contact and gives rise to another contraction of the middle constric- 
 tor. The lower constrictor is then brought into action in its turn 
 in a similar manner; and a wave-like or peristaltic contraction is 
 thence propagated throughout the entire length of the oesophagus, 
 by which the food is carried rapidly from above downward, and 
 conducted at last to the stomach. Each successive portion of the 
 raucous membrane, in this instance, receives in turn the stimulus 
 of the food, and excites instantly its own muscles to contraction ; 
 so that the food passes rapidly from one end of the oesophagus to 
 the other by an action which is wholly reflex in character and 
 entirely withdrawn from the control of the will. Section of the 
 pneumogastric, or of its pharyngeal and oesophageal branches, 
 destroys therefore at the same time the sensibility and the motive 
 power of these parts. The food is no longer conveyed readily to 
 the stomach, but accumulates in the paralyzed oesophagus, into 
 which it is forced by the voluntary movements of the mouth and 
 26 
 
402 THE CRANIAL NERVES, 
 
 fauces, and by the coDtinued action of the upper part of the 
 pharynx. 
 
 It must be remembered that the general sensibility of the oeso- 
 phagus is very slight, as compared with that of the integument, or 
 even of the mucous membranes near the exterior. It is a general 
 rule, in fact, that the sensibility of the mucous membranes is most 
 acute at the external orifices of their canals ; as, for example, at the 
 lips, anterior nares, anus, orifice of the urethra, &c. It diminishes 
 constantly from without inward, and disappears altogether at a 
 certain distance from the surface. The sensibility of the pharynx 
 is less acute than that of the mouth, but is still sufficient to enable 
 us to perceive the contact of ordinary substances ; while in the 
 oesophagus we are not usually sensible of the impression of the 
 food as it passes from above downward. The reflex action takes 
 place here without any assistance from the consciousness ; and it 
 is only when substances of an unusually pungent or irritating 
 nature are mingled with the food, that its passage through the 
 oesophagus produces a distinct sensation. 
 
 Larynx. — We have already described the course and distribution 
 of the two laryngeal branches of the pneumogastric. The superior 
 laryngeal nerve is principally the sensitive nerve of the larynx. 
 Its division destroys sensibility in the mucous membrane of this 
 organ, but paralyzes only one of its muscles, viz : the crico-thyroid. 
 Galvanization of this nerve has also been found to induce con- 
 tractions in the crico-thyroid, but in none of the other muscles 
 belonging to the larynx. The inferior laryngeal, on the other 
 hand, is a motor nerve. Its division paralyzes all the muscles of 
 the larynx except the crico-thyroid, and irritation of its divided 
 extremity produces contraction in the same muscles. The muscles 
 and mucous membrane of the larynx are therefore supplied by two 
 different branches of the same trunk, viz., the superior laryngeal 
 nerve for the mucous membrane, and the inferior laryngeal nerve 
 for the muscles. 
 
 The larynx, in man and in all the higher animals, performs a 
 double function ; one part of which is connected with the voice, the 
 other with respiration. 
 
 The formation of the voice in the larynx takes place as follows. 
 If the glottis be exposed in the living animal, as already described 
 in a previous chapter (Section I., Chap. XII.), it will be seen that 
 so long as the vocal chords preserve their usual relaxed condition 
 during expiration, no sound is heard, except the ordinary faint 
 
PNEUMOGASTRIC. 403 
 
 whisper of the air passing gently through the cavity of the larynx. 
 When a vocal sound, however, is to be produced, the chorus are 
 suddenly made tense and applied closely to each other, so as to 
 diminish very considerabl}"- the size of the orifice; and the air, 
 driven by an unusually forcible expiration through the narrow 
 opening of the glottis, in passing between the vibrating vocal 
 chords, is itself thrown into vibrations which produce the sound 
 required. The tone, pitch, and intensity of this sound, vary with 
 the conformation o the larynx, the degree of tension and approxi- 
 mation of the vocal chords, and the force of the expiratory effort. 
 The narrower the opening of the glottis, and the greater the 
 tension of the chords, under ordinary circumstances, the more 
 acute the sound; while a wider opening and a less degree of 
 tension produce a graver note. The quality of the sound is also 
 modified by the length of the column of air included between the 
 glottis and the month, the tense or relaxed condition of the walls 
 of the pharynx and fauces, and the state of dryness or moisture 
 of the mucous membrane lining the aerial passages. 
 
 Articulation, on the other hand, or the division of the vocal 
 sound into vowels and consonants, is accomplished entirely by the 
 lips, tongue, teeth, and fauces. These organs, however, are under 
 the control of other nerves, and the mechanism of their action need 
 not occupy us here. 
 
 Since the production of a vocal sound, therefore, depends upon 
 the tension and position of the vocal chords, as determined by the 
 action of the laryngeal muscles, it is not surprising that division of 
 the inferior laryngeal nerves, by paraljT'zing these muscles, should 
 produce a loss of voice. It has been sometimes found that in 
 very young animals the crico-thyroid muscles, which are the only 
 ones not affected by division of the inferior laryngeal nerves, 
 are still sufficient to give some degree of tension to the vocal 
 chords, and to produce in this way an imperfect sound; but 
 usually the voice is entirely lost after such an operation. 
 
 It is a very remarkable fact, however, in this connection, that all 
 the motor filaments of the pneumogastric, which are concerned in 
 the formation of the voice, are derived from a single source. It 
 will be remembered that the pneumogastric, itself originally a 
 sensitive nerve, receives motor filaments, on leaving the cranial 
 cavity, from no less than five different nerves. Of these filaments, 
 however, those coming from the spinal accessory are the only ones 
 necessary to the production of vocal sounds. For it has been 
 
404 THE CRANIAL NEEVES. 
 
 found by Bischofif and by Bernard^ that if all the roots of the 
 spinal accessory be divided at their origin, or if the nerve itself 
 be torn away at its exit from the skull, all the other cranial nerves 
 remaining untouched, the voice is lost as completely as if the 
 inferior laryngeal itself had been destroyed. All the motor fibres 
 of the pneumogastric, therefore, which act in the formation of the 
 voice are derived, by inosculation, from the spinal accessory nerve. 
 In respiration^ again, the larynx performs another and still more 
 important function. In the first place, it stands as a sort of guard, 
 or sentinel, at the entrance of the respiratory passages, to prevent 
 the intrusion of foreign substances. If a crumb of bread accidentally 
 fall within the aryteno-epiglottidean folds, or upon the edges of the 
 vocal chords, or upon the posterior surface of the epiglottis, the 
 sensibility of these parts immediately excites a violent expulsive 
 cough, by which the foreign body is dislodged. The impression, 
 received and conveyed inward by the sensitive fibres of the supe- 
 rior laryngeal nerve, is reflected back upon the expiratory muscles 
 of the chest and abdomen, by whicb the instinctive movements of 
 coughing are accomplished. Touching the above parts with the 
 point of a needle, or pinching them with the blades of a forceps, 
 will produce the same effect. This reaction is essentially dependent 
 on the sensibility of the laryngeal mucous membrane ; and it can 
 no longer be produced after section of the pneumogastric nerve, or 
 of its superior laryngeal branch. 
 
 In the second place, the respiratory movements of the glottis^ already 
 described in a previous chapter, are of the greatest importance to 
 the preservation of life. We have seen tbat at the moment of 
 inspiration the vocal chords are separated from each other, and the 
 glottis opened, by the action of the posterior crico arytenoid muscles; 
 and tbat in expiration the muscles and the vocal chords are botb 
 relaxed, and the air allowed to pass out readily througb the glottis. 
 The opening of the glottis in inspiration therefore is an active 
 movement, while its partial closure or collapse in expiration is a 
 passive one. Furthermore, the opening of the glottis in inspiration 
 is necessary in order to afford a sufficiently wide passage for the 
 air, in its way to the trachea, bronchi, and pulmonary vesicles. 
 
 Now we have found, as Budge and Longet had previously no- 
 ticed, that if the inferior laryngeal nerve on the right side be 
 divided while the glottis is exposed as above, the respiratory move- 
 
 ' Reclierclies Experimentales sur les fonctions du nerf spinal. Paris, 1851. 
 
PNEUMOGASTEIC. 405 
 
 ments of the right vocal chord instantly cease, owing to the para- 
 lysis of the posterior crico-arytenoid muscle on that side. If the 
 inferior laryngeal nerve on the left side be also divided, the para- 
 lysis of the glottis is then complete, and its respiratory movements 
 cease altogether. A serious difficulty in respiration is the imme- 
 diate consequence of this operation. For the vocal chords, being 
 no longer stretched and separated from each other at the moment of 
 inspiration, but remaining lax and flexible, act as a double valve, 
 and are pressed inward by the column of inspired air ; thus par- 
 tially blocking up the passage and impeding the access of air to 
 the lungs. If the pneumogastrics be divided in the middle of the 
 neck, the larynx is of course paralyzed precisely as after section 
 of the inferior laryngeal nerves, since these nerves are given ofi" 
 only after the main trunks have entered the cavity of the chest ; 
 and the immediate effect of either of these operations is to produce 
 a difficulty of inspiration, accompanied by a peculiar wheezing or 
 sucking noise, evidently produced in the larynx and dependent on 
 the falling together of the vocal chords. In very young animals, 
 as for example in pups of a few days old, in whom the glottis is 
 smaller and the larynx less rigid than in adult dogs, this difficulty 
 is much more strongly marked. Legallois' has even seen a pup of 
 two days old almost instantly suffocated after section of the two 
 inferior laryngeal nerves. We have found that in pups of two 
 weeks old, division of the inferior laryngeals is followed by death 
 at the end of from thirty to forty hours, evidently from impeded 
 respiration. 
 
 The importance, therefore, of these movements of the glottis in 
 respiration becomes very evident. They are, in fact, part and 
 parcel of the general respiratory movements, and are necessary to 
 a due performance of the function. It has been found, moreover, 
 that the motor filaments concerned in this action are not derived, 
 like those of the voice, from a single source. While the vocal 
 movements of the larynx are arrested, as mentioned above, by 
 division of the spinal accessory alone, those of respiration still go 
 on ; and in order to put a stop to the latter, either the pneumo- 
 gastrics themselves must be divided, or all five of the motor nerves 
 from which their accessory filaments are derived. This fact has 
 been noticed by Longet as showing that nature multiplies the safe- 
 guards of a function in proportion to its importance ; for while the 
 
 ' lu Longet's Traite de Physiologie. vol. ii. p. 324. 
 
406 THE CEANIAL NERVES. 
 
 spinal accessory, or any other one of the above mentioned nerves, 
 might be affected by local accident or disease, it would be very 
 improbable that any single injury should paralyze simultaneously 
 the spinal acessory, the facial, the sublingual, and the first and 
 second cervicals. The respiratory movements of the larynx are 
 consequently much more thoroughly protected than those which 
 are merely concerned in the formation of the voice. 
 
 Lungs. — The influence of the pneumogastric upon the function 
 of the lungs is exceedingly important. The nerve acts here, as in 
 most other organs to which it is distributed, in a double or mixed 
 capacity ; but it is principally as the sensitive nerve of the lungs 
 that it has thus far received attention. It is this nerve which 
 conveys from the lungs to the medulla oblongata that peculiar 
 impression, termed hesoin de respirer, which excites by reflex action 
 the diaphragm and intercostal muscles, and keeps up the play of 
 the respiratory movements. As we have already shown, this action 
 is an involuntary one, and will even take place when consciousness 
 is entirely suspended. It may indeed be arrested for a time by an 
 effort of the will; but the impression conveyed to the medulla soon 
 becomes so strong, and the stimulus to inspiration so urgent, that 
 it can no longer be resisted, and the muscles contract in spite of our 
 attempts to restrain them. 
 
 A very remarkable effect is accordingly produced on respiration 
 by simultaneous division of both pneumogastric nerves. This 
 experiment is best performed on adult dogs, which may be ether- 
 ized, and the nerves exposed while the animal is in a condition of 
 insensibility, avoiding, in this way, the disturbance of respiration, 
 which would follow if the dissection were performed while the ani- 
 mal was conscious and sensible to pain. After the effects of the 
 etherization have entirely passed off, and respiration and circulation 
 have both returned to a quiescent condition, the two nerves, which 
 have been previously exposed and secured by a loose ligature, may 
 be instantaneously divided, and the effects of the operation readily 
 appreciated. 
 
 Immediately after the division of the nerves, when performed in 
 the above manner, the respiration is hurried and difStcult, owing to 
 the sudden paralysis of the larynx and partial closure of the glottis 
 by the vocal chords, as already described. This condition, how- 
 ever, is of short continuance. In a few moments, the difficulty of 
 breathing and the general agitation subside, the animal becomes 
 perfectly quiet, and the only remaining visible effect of the opera- 
 
PNEUMOGASTRIC. 407 
 
 tion is a dimimshed fnquency in the movements of respiration. This 
 diminution is frequently strongly marked from the first, the number 
 of respirations falling at once to ten or fifteen per minute, and be- 
 coming, in an hour or two, still farther reduced. The respirations 
 are performed easily and quietly ; and the animal, if left undisturbed, 
 remains usually crouched in a corner, without giving any special 
 signs of discomfort. If he be aroused and compelled to move 
 about, the frequency of the respiration is temporarily augmented ; 
 but as soon as he is again quiet, it returns to its former standard. 
 By the second or third day, the number of respirations is often 
 reduced to five, four, or even three per minute; when this is the 
 case, the animal usually appears very sluggish, and is roused with 
 difficulty from his inactive condition. At this time, the respiration 
 is not only diminished in frequency, but is also performed in a 
 peculiar manner. The movement of inspiration is slow, easy, and 
 silent, occupying several seconds in its accomplishment; expiration, 
 on the contrary, is sudden and audible, and is accompanied by a well 
 marked expulsive effort, which has the appearance of being, to a 
 certain extent, voluntary in character. The intercostal spaces also 
 sink inward during the lifting of the ribs; and the whole movement 
 of respiration has an appearance of insufficiency, as if the lungs 
 were not thoroughly filled with air. This insufficiency of respira- 
 tion is undoubtedly owing to a peculiar alteration in the pulmonary 
 texture, which has by this time already commenced. 
 
 Death takes place at a period varying from one to six days after 
 the operation, according to the age and strength of the animal. 
 The only symptoms accompanying it are a steady failure of the 
 respiration, with increased sluggishness and indisposition to be 
 aroused. There are no convulsions, nor any evidences of pain. 
 After death, the lungs are found in a peculiar state of solidification, 
 which is almost exclusively a consequence of this operation, and 
 which is entirely different from ordinary inflammatory hepatization. 
 They are not swollen, but rather smaller than natural. They are 
 of a dark purple color, leathery and resisting to the feel, destitute 
 of crepitation, and infiltrated with blood. Pieces of the lung cut 
 out sink in water. The pleural surfaces, at the same time, are bright 
 and polished, and their cavity contains no effusion or exudation. 
 The lungs, in a word, are simply engorged with blood and empty 
 of air; their tissue having undergone no other alteration. 
 
 These changes are not generally uniform over both lungs. The 
 organs are usually mottled on their exterior; the variations in color 
 
408 THE CRANIAL NERVES. 
 
 corresponding with the different degrees of alteration exhibited by 
 different parts. 
 
 The explanation usually adopted of the above consequences fol- 
 lowing division of the pneumogastrics is as follows: The nerves 
 being divided, the impression which originates in the lungs from 
 the accumulation of carbonic acid, and which is destined to excite 
 the respiratory movements by reflex action, can no longer be trans- 
 mitted to the medulla oblongata. The natural stimulus to respira- 
 tion being wanting, it is, accordingly, less perfectly performed. The 
 respiratory movements diminish in frequency, and, growing con- 
 tinually slower and slower, finally cease altogether, and death is the 
 result. 
 
 The above explanation, however, is not altogether sufficient. It 
 accounts very well for the diminished frequency of the respiration, 
 but not for its partial continuance. For if the pneumogastric nerves 
 be really the channel through which the stimulus to respiration is 
 conveyed to the medulla, the difficulty is not to understand why 
 respiration should be retarded after division of these nerves, but 
 why it should continue at all. In point of fact, the respiratory 
 movements, though diminished in frequency, continue often for 
 some days after this operation. This cannot be owing to force of 
 habit, or to any remains of nervous influence, as has been some- 
 times suggested, since, when the medulla itself is destroyed, respira- 
 tion, as we know, stops instantaneously, and no attempt at move- 
 ment is made after the action of the nervous centre is suspended. 
 
 It is evident, therefore, that the pneumogastric nerve, though the 
 chief agent by which the respiratory stimulus is conveyed to the 
 medulla, is not the only one. The lungs are undoubtedly the 
 organs which are most sensitive to an accumulation of carbonic 
 acid, and an imperfect arterialization of the blood ; and the sensa- 
 tion which results from such an accumulation is accordingly first 
 felt in them. There is reason to believe, however, that all the vas- 
 cular organs are more or less capable of originating this impression, 
 and that all the sensitive nerves are capable, to some extent, of trans- 
 mitting it. Although the first disagreeable sensation on holding 
 the breath makes itself felt in the lungs, yet, if we persist in sus- 
 pending the respiration, we soon become conscious that the feeling 
 of discomfort spreads to other parts ; and at last, when the accu- 
 mulation of carbonic acid and the impurity of the blood have 
 become excessive, all parts of the body suffer alike, and are per- 
 vaded by a general feeling of derangement and distress. It is easy. 
 
PNEUMOGASTRIC. 409 
 
 therefore, to understand why respiration should be retarded, after 
 section of the pneumogastrics, since the chief source of the stimulus 
 to respiration is cut ofl"; but the movements still go on, though more 
 slowly than before, because the other sensitive nerves, which con- 
 tinue to act, are also capable, in an imperfect manner, of conveying 
 the same impression. 
 
 The immediate cause of death, after this operation, must no 
 doubt be principally sought for in the altered condition of the 
 lungs. These organs are evidently very imperfectly filled with air, 
 for some time previous to death ; and their condition, as shown in 
 post-mortem examination, is evidently incompatible with a due 
 performance of the respiratory function. It is not at all certain, 
 however, that these alterations in the pulmonary tissue are directly 
 dependent on division of the pneumogastric nerves. It must be 
 recollected that when the section of the pneumogastrics is performed 
 in the middle of the neck, the filaments of the inferior laryngeal 
 nerves are also divided, and the narrowing of the glottis, produced 
 by their paralysis, must necessarily interfere with the free admission 
 of air into the chest. This diflSculty, either alone or combined with 
 the diminished frequency of respiration, must have a very con- 
 siderable effect in impeding the pulmonary circulation, and bringing 
 the lungs into such a condition as unfits them for maintaining life. 
 
 In order to ascertain the comparative influence upon the lungs 
 of division of the inferior laryngeals and that of the other filaments 
 of the pneumogastrics, we have resorted to the following experi- 
 ment. 
 
 Two pups were taken, belonging to the same litter and of the 
 same size and vigor, about two weeks old. In one of them (No. 1) 
 the pneumogastrics were divided in the middle of the neck; and 
 in the other (No. 2) a section was made at the same time of the 
 inferior laryngeals, the trunk of the pneumogastrics being left un- 
 touched. For the first few seconds after the operation, there was 
 but little difi'erence in the condition of the two animals. There was 
 the same obstruction to the breath (owing to closure of the glottis), 
 the same gasping and sucking inspiration, and the same frothing at 
 the mouth. Yery soon, however, in pup No. 1, the respiratory move- 
 ments became quiescent, and at the same time much reduced in 
 frequency, falling to ten, eight, and five respirations per minute, as 
 usual after section of the pneumogastrics ; while in No. 2 the re- 
 spiration continued frequent as well as laborious, and the general 
 signs of agitation and discomfort were kept up for one or two hours. 
 
410 THE CKANIAL NERVES. 
 
 The animal, however, after that time became exhausted, cool, and 
 partially insensible, like the other. They both died, between thirty 
 and forty hours after the operation. On post-mortem inspection it 
 was found that the peculiar congestion and solidification of the 
 lungs, considered as characteristic of division of the pneumogastrics, 
 existed to a similar extent in each instance ; and the only appre- 
 ciable difference between the two bodies was that in No. 1 the blood 
 was coagulated, and the abdominal organs natural, while in No. 2 
 the blood was fluid and the abdominal organs congested. We are 
 led, accordingly, to the following conclusions with regard to the 
 effect produced by division of this nerve. 
 
 1. After section of the pneumogastrics, death takes place by a pecu- 
 liar congestion of the lungs. 
 
 2. This congestion is not directly produced by division of the 
 nerves, but is caused by the imperfect admission of air into the 
 chest. 
 
 In adult dogs, the closure of the glottis from paralysis of the 
 laryngeal muscles is less complete than in pups ; but it is still 
 sufficient to exert a very decided influence on respiration, and to 
 take an active part in the production of the subsequent morbid 
 phenomena. 
 
 We therefore regard the death which takes place after division 
 of both pneuraogastric nerves, as produced in the following man- 
 ner : — 
 
 The glottis is first narrowed by paralysis of the laryngeal mus- 
 cles, and an imperfect supply of air is consequently admitted, by 
 each inspiration, into the trachea. Next, the stimulus to respiration 
 being very much diminished, the respiratory movements take place 
 more slowly than usual. From these two causes combined, the 
 blood is imperfectly arterialized, and the usual consequence of such 
 a condition then follows, viz., a partial stagnation of the pulmonary 
 circulation. This stagnation still further impedes the action of the 
 lungs; while it does not excite the respiratory muscles to increased 
 activity as it would do in health, owing to the division of the pneu- 
 mogastrics. At the same time, the accumulation of carbonic acid 
 in the blood and the tissues begins to exert a narcotic effect, to 
 diminish the sensibility of the nervous centres, and consequently 
 to retard still more the movements of respiration. Thus all these 
 causes react upon and aggravate each other ; because the connection 
 naturally existing between imperfectly arterialized blood and the 
 stimulus to respiration, is now destroyed. The narcotism and pul- 
 
PNEUMOGASTRIC. 411 
 
 monary engorgement, therefore, continue to increase, until the lungs 
 are so seriously altered and engorged that they are no longer capable 
 of transmitting the blood, and circulation and respiration come to 
 an end at the same time. 
 
 It must be remembered, also, that the pneumogastric nerve has 
 other important distributions beside those to the larynx and the 
 lungs; and the effect produced by its division upon these other 
 organs has no doubt a certain share in producing the results which 
 follow. Bearing in mind the very extensive distribution of the 
 pneumogastric nerve and the complicated character of its func- 
 tions, we may conclude that after section of this nerve death takes 
 place from a combination of various causes ; the most active of 
 which is a peculiar engorgement of the lungs and imperfect per- 
 formance of the respiratory function. 
 
 S(o7nach, and Digestive Function. — After division of the pneumo- 
 gastric nerves, the sensations of hunger and thirst remain, and the 
 secretion of gastric juice continues. Nevertheless the digestive 
 function is disturbed in various ways, though not altogether abo- 
 lished. The appetite is more or less diminished, as it would be after 
 any serious operation, but it remains sufficiently active to show that 
 its existence is not directly dependent on the integrity of the pneu- 
 mogastric nerve. Digestion, however, very seldom actually takes 
 place to any considerable extent, owing to the following circum- 
 stances : The animal is frequently seen to take food and drink with 
 considerable avidity; but in a few moments afterward the food and 
 drink are suddenly rejected by a peculiar kind of regurgitation. 
 This regurgitation does not resemble the action of vomiting, but 
 the substances swallowed are again discharged so easily and instan- 
 taneously as to lead to the belief that they had never passed into 
 the stomach. Such, indeed, is actually the case, as any one may 
 convince himself by watching the process, which is often repeated 
 by the animal at short intervals. The food and drink, taken volun- 
 tarily, pass down into the oesophagus, but owing to the paralysis of 
 the muscular fibres of this canal, are not conveyed into the stomach. 
 They accumulate consequently in the lower and middle part of the 
 oesophagus ; and in a few moments are rejected by a sudden anti- 
 staltic action of the parts, excited, apparently, through the influence 
 of the great sympathetic. 
 
 The muscular coat of the stomach is also paralyzed to a con- 
 siderable extent by section of this nerve. Longet has shown, by 
 introducing food artificially into the stomach, that gastric juice 
 
412 THE CRANIAL NERVES. 
 
 may be secreted and the food be actually digested and disappear, 
 when introduced in small quantity. But when introduced in large 
 quantity, it remains undigested, and is found after death with the 
 exterior of the mass softened and permeated by gastric juice, while 
 the central portions are unaltered, and do not even seem to have 
 come in contact with the digestive fluid. This is undoubtedly 
 owing both to the diminished sensibility of the mucous membrane 
 of the stomach, and to the paralysis of its muscular fibres. The 
 peristaltic action of the organ is very important in digestion, in 
 order to bring successive portions of the food in contact with the 
 mucous membrane, and to carry away such as are already softened 
 or as are not capable of being digested in the stomach. This 
 constant movement and agitation of the food is probably also one 
 great stimulus to the continued secretion of the gastric juice. The 
 digestive fluid will therefore be deficient in quantity after division 
 of the pneumogastric nerves, at the same time that the peristaltic 
 movements of the stomach are suspended. Under these circum- 
 stances, the secretion of gastric juice may be sufficient to permeate 
 and digest small quantities of food, while a larger mass may resist 
 its action, and remain undigested. The effect produced by division 
 of these nerves on the digestive, as on the respiratory organs, is 
 therefore of a complicated character, and results from the combined 
 action of several different causes, which influence and modify each 
 other. 
 
 The effect produced upon the liver by section of the pneumo- 
 gastrics, as well as the influence usually exerted by these nerves 
 upon the hepatic functions, has been so little studied that nothing 
 definite has been ascertained in regard to it. We shall therefore 
 pass over this portion of the subject in silence. 
 
 That part of the nervous system which we have hitherto 
 studied, viz., the cerebro-spinal system, consists of an apparatus of 
 nerves and ganglia, destined to bring the individual into relation 
 with the external world. By means of the special senses, he is 
 made cognizant of sights, sounds, and odors, by which he is 
 attracted or repelled, and which guide him in the pursuit and 
 choice of food. By the general sensations of touch and the volun- 
 tary movements, he is enabled to alter at will his position and 
 location, and to adapt them to the varying conditions under which 
 he may be placed. The great passages of entrance into the body, 
 and of exit from it, are guarded also by the same portion of the 
 nervous system. The introduction of food into the mouth, and its 
 
PNEUMOGASTRIC. 413 
 
 passage through the oesophagus to the stomach, are regulated by 
 the same nervous apparatus ; and even the passage of air through 
 the larynx, and its penetration into the lungs, are equally under 
 the guidance of sensitive and motor nerves belonging to the 
 cerebro-spinal system. 
 
 It will be observed that the above functions relate altogether 
 either to external phenomena or to the simple introduction into the 
 body of food and air, which are destined to undergo nutritive 
 changes in the interior of the frame. 
 
 If we examine, however, the deeper regions of the body, we find 
 located in them a series of internal phenomena, relating only to 
 the substances and materials which have already penetrated into 
 the frame, and which form or are forming a part of its structure. 
 These are the purely vegetative functions, as they are called ; or 
 those of growth, nutrition, secretion, excretion, and reproduction. 
 These functions, and the organs to which they belong, are not 
 under the direct influence of the cerebro-spinal nerves, but are 
 regulated by another portion of the nervous system, viz., the 
 "ganglionic system;" or, as it is more commonly called, the "sys- 
 tem of the great sympathetic." 
 
414 SYSTEM OF THE GREAT SYMPATHETIC. 
 
 CHAPTER VI. 
 
 SYSTEM OF THE GREAT SYMPATHETIC. 
 
 The sympathetic system consists of a double chain of nervous 
 ganglia, running from the anterior to the posterior extremity of the 
 body, along the front and sides of the spinal column, and connected 
 with each other by slender longitudinal filaments. Each ganglion 
 is reinforced by a motor and sensitive filament derived from the 
 cerebro-spinal system, and thus the organs under its influence are 
 brought indirectly into communication with external objects and 
 phenomena. The nerves of the great sympathetic are distributed 
 to organs over which the consciousness and the will have no imme- 
 diate control, as the intestine, kidneys, heart, liver, &c. 
 
 The first sympathetic ganglion in the head is the ophthalmic gan- 
 glion. This ganglion is situated within the orbit of the eye, on the 
 outer aspect of the optic nerve. It communicates by slender fila- 
 ments with the carotid plexus, which forms the continuation of the 
 sympathetic system from below; and receives a motor root from 
 the oculo-motorius nerve, and a sensitive root from the ophthalmic 
 branch of the 5th pair. Its filaments of distribution, known as the 
 "ciliary nerves," pass forward upon the eyeball, pierce the sclerotic, 
 and finally terminate in the iris. 
 
 The next division of the great sympathetic in the head is the 
 sphenopalatine ganglion, situated in the spheno-maxillary fossa. It 
 communicates, like the preceding, with the carotid plexus, and 
 receives a motor root from the facial nerve, and a sensitive root 
 from the superior maxillary branch of the 5th pair. Its filaments 
 are distributed to the levator palati and azygos uvulae muscles, and 
 to the mucous membrane about the posterior nares. 
 
 The third sympathetic ganglion in the head is the submaxillary, 
 situated upon the submaxillary gland. It communicates with the 
 superior cervical ganglion of the sympathetic by filaments which 
 accompany the facial and external carotid arteries. It derives its 
 sensitive filaments from the lingual branch of the 5th pair, and its 
 
SYSTEM OF THE GREAT SYMPATHETIC. 
 
 415 
 
 Fiff. 149. 
 
 motor filaments from the facial nerve, by means of the chorda 
 tympani. Its branches of distribution pass to the sides of the tongue 
 and to the submaxillary and sublingual glands. 
 
 The last sympathetic ganglion in the head is the otic ganglion. 
 It is situated just beneath the 
 base of the skull, on the inner 
 side of the third branch of the 
 trifacial nerve. It sends fila- 
 ments of communication to 
 the carotid plexus; and re- 
 ceives a motor root from the 
 facial nerve, and a sensitive 
 root from the inferior maxil- 
 lary branch of the 5th pair. 
 Its branches are sent to the 
 internal muscle of the mal- 
 leus in the middle ear (tensor 
 tympani), and to the mucous 
 membrane of the tympanum 
 and Eustachian tube. 
 
 The continuation of the 
 sympathetic nerve in the neck 
 consists of two and some- 
 times of three ganglia, the 
 superior, middle, and inferior. 
 These ganglia communicate 
 with each other, and also 
 with the anterior branches 
 of the cervical spinal nerves. 
 Their filaments follow the 
 course of the carotid artery 
 and its branches, covering 
 them with a network of inter- 
 lacing fibres, and are finally 
 distributed to the substance of 
 the thyroid gland, and to the 
 
 Course and distribution of the Great Sympa- 
 thetic. 
 
 walls of the larynx, trachea, 
 
 pharynx, and oesophagus. By the superior, middle, and inferior 
 cardiac nerves, they also supply sympathetic fibres to the cardiac 
 plexuses and to the substance of the heart. 
 
 In the chest, the ganglia of the sympathetic nerve are situated on 
 
416 SYSTEM OF THE GREAT SYMPATHETIC. 
 
 each side the spinal column, just over the heads of the ribs, with 
 which they accordingly correspond in number. Their communi- 
 cations with the intercostal nerves are double ; each sympathetic 
 ganglion receiving two filaments from the intercostal nerve next 
 above it. The filaments originating from the thoracic ganglia are 
 distributed upon the thoracic aorta, and to the lungs and oesophagus. 
 In the abdomen, the continuation of the sympathetic system con- 
 sists principally of the aggregation of ganglionic enlargements 
 situated upon the cceliac artery, known as the semilunar or coeliac 
 ganglion. From this ganglion a multitude of radiating and inoscu- 
 lating branches are sent out, which, from their diverging course and 
 their common origin from a central mass, are termed the "solar 
 plexus," From this, other diverging plexuses originate, which 
 accompany the abdominal aorta and its branches, and are so dis- 
 tributed to the stomach, small and large intestine, spleen, pancreas, 
 liver, kidneys, and supra-renal capsules, and the internal organs of 
 generation. 
 
 Beside the above ganglia there are in the abdomen four other 
 pairs, situated in front of the lumbar vertebrae, and having similar 
 connections with those occupying the cavity of the chest. Their 
 filaments join the plexuses radiating from the semilunar ganglion. 
 
 In the pelvis, the sympathetic system is continued by four or five 
 pairs of ganglia, situated on the anterior aspect of the sacrum, and 
 terminating, at the lower extremity of the spinal column, in a single 
 ganglion, the " ganglion impar," which is probably to be regarded 
 as a fusion of two separate ganglia. 
 
 The entire sympathetic series is in this way composed of nume- 
 rous small ganglia which are connected throughout, first, with each 
 other, secondly, with the cerebro-spinal system, and thirdly, with 
 the internal viscera of the body. 
 
 The properties and functions of the great sympathetic have been 
 less successfully studied than those of the cerebro-spinal system, 
 owing to the anatomical difficulties in the way of reaching and 
 operating upon this nerve for purposes of experiment. The cerebro- 
 spinal axis and its nerves are easily exposed and subjected to exami- 
 nation. It is also easy to isolate particular portions, and to appreciate 
 the disturbances of sensation and motion consequent upon local 
 lesions or irritations. The phenomena, furthermore, which result 
 from experiments upon this part of the nervous system, are promptly 
 produced, are well-marked in character, and are, as a general rule, 
 readily understood by the experimenter. On the other hand, the 
 
SYSTEM OP THE GREAT SYMPATHETIC. 417 
 
 principal part of the sympathetic system is situated in the interior 
 of the chest and abdomen ; and the mere operation of opening these 
 cavities, so as to reach the ganglionic centres, causes such a disturb- 
 ance in the functions of vital organs, and such a shock to the system 
 at large, that the results of these experiments have been always 
 more or less confused and unsatisfactory. Furthermore, the con- 
 nections of the sympathetic ganglia Avith each other and with the 
 cerebro-spinal axis are so numerous and scattered, that these ganglia 
 cannot be completely isolated without resorting to an operation still 
 more mutilating and injurious in its character. And finally, the 
 sensible phenomena which are obtained from experimenting on the 
 great sympathetic are, in the majority of cases, slow in making 
 their appearance, and not particularly striking or characteristic in 
 their nature. 
 
 Notwithstanding these difficulties, however, some facts have been 
 ascertained with regard to this part of the nervous system, which 
 give us a certain degree of insight into its character and functions. 
 
 The great sympathetic is endowed both with sensibility and the 
 power of exciting motion; but these properties are less active 
 here than in the cerebro-spinal system, and are exercised in a dif- 
 ferent manner. If we irritate, for example, a sensitive nerve in 
 one of the extremities, or apply the galvanic current to the poste- 
 rior root of a spinal nerve, the evidences of pain or of reflex 
 action are acute and instantaneous. There is no appreciable inter- 
 val between the application of the stimulus and the sensations 
 which result from it. On the other hand, experimenters who have 
 operated upon the sympathetic ganglia and nerves of the chest and 
 abdomen find that evidences of sensibility are distinctly manifested 
 here also, but less acutely and only after somewhat prolonged ap- 
 plication of the irritating cause. These results correspond very 
 closely with what we know of the vital properties of the organs 
 which are supplied either principally or exclusively by the sympa- 
 thetic; as the liver, intestine, kidneys, &c. These organs are 
 insensible, or nearly so, to ordinary impressions. We are not con- 
 scious of the changes and operations going on in them, so long as 
 these changes and operations retain their normal character. But 
 they are still capable of perceiving unusual or excessive irritations, 
 and may even become exceedingly painful, when in a state of in- 
 flammation. 
 
 There is the same peculiar character in the action of the motor 
 nerves belonging to the sympathetic. If the facial or sublingual, 
 27 
 
418 SYSTEM OF THE GREAT SYMPATHETIC. 
 
 or the anterior root of a spinal nerve be irritated, the convulsive 
 movement which follows is instantaneous, violent, and only mo- 
 mentary in its duration. But if the semilunar ganglion or its 
 nerves be subjected to a similar experiment, no immediate effect is 
 produced. It is only after a few seconds that a slow, vermicular, 
 progressive contraction takes place in the corresponding part of the 
 intestine, which continues for some time after the exciting cause 
 has been removed. 
 
 Morbid changes taking place in organs supplied by the sympa- 
 thetic present a similar peculiarity in the mode of their produc- 
 tion. If the body be exposed to cold and dampness, for example, 
 congestion of the kidneys shows itself perhaps on the following 
 (lay. Inflammation of any of the internal organs is very rarely 
 established within twelve or twenty-four hours after the application 
 of the exciting cause. The internal processes of nutrition together 
 with their derangements, which are regarded as especially under 
 the control of the great sympathetic, always require a longer time 
 to be influenced by incidental causes, than those which are regulated 
 by the nerves and ganglia of the cerebro-spinal system. 
 
 In the head, the sympathetic has a close and important connec- 
 tion with the exercise of the special senses. This is illustrated 
 more particularly, in the case of the eye, by its influence over the 
 alternate expansion and contraction of the pupil. The ophthalmic 
 ganglion sends off a number of ciliary nerves, which are distributed 
 to the iris. It is connected, as we have seen, with the remaining 
 sympathetic ganglia in the head, and receives, beside, a sensitive 
 root from the ophthalmic branch of the 5th pair, and a motor root 
 from the oculo-motorius. The reflex action by which the pupil 
 contracts under a strong light falling upon the retina, and expands 
 under a diminution of light, takes place accordingly through this 
 ganglion. The impression conveyed by the optic nerve to the 
 tubercula quadrigemina, and reflected outward by the fibres of 
 the oculo-motorius, is not transmitted directly by the last named 
 nerve to the iris ; but passes first to the ophthalmic ganglion, and 
 is thence conveyed to its destination by the ciliary nerves. 
 
 The reflex movements of the iris exhibit consequently a some- 
 what sluggish character, which indicates the intervention of a part 
 of the sympathetic system. The changes in the size of the pupil 
 do not take place instantaneously, with the variation in the amount 
 of light, but always require an appreciable interval of time. If 
 we pass suddenly from a brilliantly lighted apartment into a dark 
 
SYSTEM OF THE GREAT SYMPATHETIC. 419 
 
 room, we are unable to distinguish surrounding objects until a 
 certain time has elapsed, and the expansion of the pupil has taken 
 place; and vision even continues to grow more and more distinct 
 for a considerable period afterward, as the expansion of the pupil 
 becomes more complete. Again, if we cover the eyes of another 
 person with the hand or a folded cloth, and then suddenly expose 
 them to the light, we shall find that the pupil, which is at first dilated, 
 contracts somewhat rapidly to a certain extent, and afterward con- 
 tinues to diminish in size during several seconds, until the proper 
 equilibrium is fairly established. Furthermore, if we pass sud 
 denly from a dark room into the bright sunshine, we are immedi- 
 ately conscious of a painful sensation in the eye, which lasts for a 
 considerable time ; and which results from the inability of th^- 
 pupil to contract with sufficient rapidity to shut out the excessive 
 amount of light. All such exposures should be made gradually, 
 so that the movements of the iris may keep pace with the varying 
 quantity of stimulus, and so protect the eye from injurious impres- 
 sions. 
 
 The reflex movements of the iris, however, though accomplished 
 through the medium of the ophthalmic ganglion, derive their 
 original stimulus, through the motor root of this ganglion, from 
 the oculo-motorius nerve. For it has been found that if the last 
 mentioned nerve be divided between the brain and the eyeball, 
 the pupil becomes immediately dilated, and will no longer contract 
 under the influence of light. The motive power originally derived 
 from the brain is, therefore, in the case of the iris, modified by 
 passing through one of the sympathetic ganglia before it reache& 
 its final destination. 
 
 An extremely interesting fact in this connection is the following: 
 Of the three organs of special sense in the head, viz., the eye, the 
 nose, and the ear, each one is provided with two sets of muscles, 
 superficial and deep, which together regulate the quantity of stimu- 
 lus admitted to the organ. The superficial set of these muscles is 
 animated by branches of the facial nerve ; the deep seated or in- 
 ternal set, by filaments from a sympathetic ganglion. 
 
 Thus, the front of the eyeball is protected by the orbicularis and 
 levator palpebrae superioris muscles, which open or close the eye- 
 lids at will, and allow a larger or smaller quantity of light to reach 
 the cornea. These muscles are supplied by the oculo-motorius and 
 facial nerves, and are for the most part voluntary in their action. 
 The iris, on the other hand, is a more deeply-seated muscular 
 
420 SYSTEM OF THE GREAT SYMPATHETIC. 
 
 curtain, winch regulates the quantity of light admitted through the 
 pupil. It is supplied, as we have seen, by filaments from the 
 ophthalmic ganglion, and its movements are altogether involuntary 
 in character. 
 
 In the olfactory apparatus, the anterior or superficial set of 
 muscles are the compressors and elevators of the alse nasi, which 
 are animated by filaments of the facial nerve. By their action, 
 odoriferous vapors, when faint and delicate in their character, are 
 snuffed up and directed into the upper part of the nasal passages, 
 where they come in contact with the most sensitive portions of the 
 olfactory membrane ; or, if too pungent or disagreeable in flavor, 
 are excluded from entrance. These muscles are not very im- 
 portant or active in the human subject; but in many of the lower 
 animals with a more active and powerful sense of smell, as for 
 example the carnivora, they may be seen to play a very important 
 part in the mechanism of olfaction. Furthermore, the levators and 
 depressors of the velum palati, which are more deeply situated, 
 serve to open or close the orifice of the posterior nares, and accom- 
 plish a similar office with the muscles already named in front. 
 The levator palati and azygos uvulae muscles, which, by their 
 action, tend to close the posterior nares, are supplied by filaments 
 from the spheno-palatine ganglion, and are involuntary in their 
 character. 
 
 The ear has two similar sets of muscles, similarly supplied. The 
 first, or superficial set, are those moving the external ear, viz., the 
 anterior, superior, and posterior auriculares. Like the muscles of 
 the anterior nares, they are comparatively inactive in man, but 
 in many of the lower animals are well developed and important. 
 In the horse, the deer, the sheep, &c., they turn the ear in various 
 directions so as to catch more distinctly faint and distant sounds, or 
 to exclude those which are harsh and disagreeable. These muscles 
 are supplied by filaments of the facial nerve, and are voluntary in 
 their action. 
 
 The deep seated set are the muscles of the middle ear. In 
 order to understand their action, we must recollect that sounds 
 are transmitted from the external to the middle ear through the 
 membrane of the tympanum, which vibrates, like the head of a 
 drum, on receiving sonorous impulses from without. Now it is 
 well known that any resonant membrane or cord is capable of 
 vibrating in unison with acute or grave sounds, according to its 
 fctate of tension or relaxation. For any such membrane or cord, at 
 
SYSTEM OF THE GREAT SYMPATHETIC. 421 
 
 a given degree of tension, there is a limit both to the gravity and 
 acuteness of the sounds which it is capable of transmitting. The 
 greater its tension, the more acute the sounds which may be trans- 
 mitted ; the lower its tension, the deeper the sounds to which it 
 is capable of vibrating. Furthermore, any elastic membrane is 
 more easily thrown into sonorous vibrations when in a tense con- 
 dition, and is consequently more capable, when tightly strained, of 
 receiving and transmitting sounds of feeble intensity. 
 
 The membrane of the tympanum, accordingly, which is an 
 elastic sheet stretched across the passage to the ear, may be made 
 more or less sensitive to sonorous impressions by varying its con- 
 dition of tension or relaxation. The handle of the malleus is 
 attached to the membrana tympani in such a manner that when 
 the internal muscle of the malleus (tensor tympani) is thrown into 
 contraction, the tympanic membrane is drawn inward, and its 
 tension increased. On the relaxation of this muscle, the chain of 
 bones of the middle ear returns to its ordinary position by the 
 elasticity of its ligaments, and restores the previous condition of 
 the membrana tympani. It is undoubtedly by this mechanism that 
 the sensibility of the hearing is increased or diminished according 
 to circumstances. In listening attentively to a very faint sound, or 
 in endeavoring to distinguish slight variations at a high pitch, a 
 sense of exertion may be almost always perceived, which is proba- 
 bly due in a great degree to the unusual tension of the membrana 
 tympani. On the other hand, sounds of a very sharp and acute 
 character are distressing to the ear, and may be diminished in 
 apparent intensity by a relaxation of the same membrane. The 
 internal muscle of the malleus, by which this action is accom- 
 plished, corresponds therefore in its office with the muscular fibres 
 of the iris, and to those which open and close the posterior nares. 
 It is supplied by filaments from the otic ganglion, the fourth in the 
 series of sympathetic ganglia situated in the head. 
 
 In all these instances, the reflex action taking place in the 
 deeper seated muscles, originates from a sensation which is con- 
 veyed inward to the cerebro-spinal centres, and is then transmitted 
 outward to its final destination through the medium of one of the 
 sympathetic ganglia. 
 
 Another very striking fact concerning the sympathetic relates to 
 the changes produced by its division, in the nutritive processes of 
 the parts supplied by it. One of the most important and remark- 
 able of these changes is an elevation of temperalure in the affected 
 
422 SYSTEM OF THE GREAT SYMPATHETIC. 
 
 parts. If the sympathetic nerve be divided on one side of the neck, 
 in the rabbit, cat, or dog, an elevation of temperature begins to be 
 perceptible on the corresponding side of the head in a very short 
 time. In the cat, we have found a very sensible difference in tem- 
 perature between the two sides at the end of five or ten minutes ; 
 and in the rabbit, at the end of half an hour. A vascular conges- 
 tion of the parts also takes place, which may be seen to great 
 advantage in the ear of the rabbit, when held up between the eye 
 and the light. The elevation of temperature, in these cases, is very 
 perceptible to the touch, and may be also measured by the thermo- 
 meter. Bernard' has found it to reach 8° or 9° F. The elevation 
 <)f temperature and congested state of the parts are sometimes found 
 to be diminished by the next day, and afterward disappear rapidly. 
 Occasionally, however, they last for a long time. Bernard {op. cit.) 
 has seen the unnatural temperature of the affected parts remain in 
 the rabbit for fifteen to eighteen days, and in the dog for two 
 months. Where the superior cervical ganglion has been extir- 
 pated, he has even found the above appearances to continue in the 
 <log for a year and a half. They may also, according to the same 
 authority, be reproduced several times in the same animal, by 
 repeated divisions of the sympathetic nerve. 
 
 The above effects are due to a peculiar modification in the nutri- 
 tion of the affected parts, which has some analogy with inflamma- 
 tion. The unnatural heat, the congestion, and the increased sensi- 
 bility which, are present, all serve to indicate a certain resemblance 
 between the two conditions. None of the more serious consequences 
 of inflammation, however, such as oedema, exudation, sloughing or 
 ulceration, have ever been known to follow from this operation ; 
 and the term inflammation, accordingly, cannot properly be applied 
 to its results. 
 
 Division of the sympathetic nerve in the middle of the neck 
 has also a very singular and instantaneous effect on the muscular 
 apparatus of the eye. Within a very few seconds after the above 
 operation has been performed upon the cat, the pupil of the cor- 
 responding eye becomes strongly contracted, and remains in that 
 condition. At the same time the third eyelid, or "nictitating mem- 
 brane," with which these animals are provided, is drawn partially 
 over the cornea, and the upper and lower eyelids also approxi- 
 mate very considerably to each other; so that all the apertures 
 
 ' Reclierches experimentales sur le Grand Sympatliique. Paris, 1854. 
 
SYSTEM OF TPIE GREAT SYMPATHETIC. 
 
 423 
 
 Fiff. 150. 
 
 Cat, after section of the right sympathetic. 
 
 guarding the eyeball are very perceptibly narrowed, and the ex- 
 pression of the face on that side is altered in a corresponding degree. 
 This effect upon the pupil has been explained by supposing the 
 circular fibres of the iris, or the 
 constrictors of the pupil, to be 
 .inimated exclusively by nervous 
 filaments derived from the oculo- 
 motorius ; and the radiating fibres, 
 or the dilators, to be supplied by 
 the sympathetic. Accordingly, 
 while division of the oculo-mo- 
 torius would produce dilatation 
 of the pupil (as it actually does), 
 by paralysis of the circular fibres 
 only, division of the sympathetic 
 would be followed by exclusive 
 paralysis of the dilators, and a per- 
 manent contraction of the pupil would consequently take place. The 
 above explanation, however, is not a satisfactory one ; since after 
 division of the sympathetic nerve in the cat, as we have already 
 shown, not only is the pupil contracted, but both the upper and lower 
 eyelids and the nictitating membrane are also partially drawn over 
 the cornea, and assist in excluding the light. The last-named effect 
 cannot be owing to any direct paralysis, from division of the fibres 
 of the sympathetic. It is more probable that the section of this 
 nerve operates simply by exaggerating for a time the sensibility of 
 the retina, as it does that of the integument ; and that the partial 
 closure of the eyelids and pupil is a secondary consequence of that 
 condition. 
 
 It will be remembered that in describing the inflammation of the 
 eyeball, consequent upon section of the fifth pair of nerves, we 
 found that there were reasons for believing this effect to be due to 
 injury of certain sympathetic fibres which accompany the fifth pair. 
 If the fifth pair in fact be divided at the level of the Casserian gan- 
 glion, where it is joined by sympathetic fibres from the carotid 
 plexus, or between this ganglion and the eyeball, a destructive 
 inflammation of the organ follows. But if the section be made 
 behind the ganglion, so as to avoid the filaments of communication 
 with the sympathetic, no inflammatory change takes place. If this 
 fact be really owing to the presence of s^^mpathetic fibres which 
 
424 SYSTEM OF THE GKEAT SYMPATHETIC. 
 
 accompany the fifth pair, it indicates a remarkable difference in the 
 effects of dividing the sympathetic near the eyeball and at a dis- 
 tance from it ; since no real inflammation of the eyeball or its 
 appendages is ever produced by division of this nerve in the middle 
 of the neck, but only the elevation of temperature and increase of 
 sensibility which have been already described. 
 
 The influence of the sympathetic nerve and the consequences 
 of its division upon the thoracic and abdominal viscera have been 
 only very imperfectly investigated by experimental methods. It 
 undoubtedly serves as a medium of reflex action between the sensi- 
 tive and motor portions of the digestive, excretory, and generative 
 apparatuses ; and it is certain that it also takes part in reflex actions 
 in which the cerebro-spinal system is at the same time interested. 
 There are accordingly three different kinds of reflex action, taking 
 place wholly or partially through the sympathetic system, which 
 may be observed to occur in the living body. 
 
 1st. Refiex actions taking place from the irdernal organs, through the 
 sym.pathetic and cerebro-spinal systems, to the voluntary muscles and 
 sensitive surfaces. — The convulsions of young children are often 
 owing to the irritation of the undigested food in the intestinal canal. 
 Attacks of indigestion are also known to produce temporary amau- 
 rosis, double vision, strabismus, and even hemiplegia. Nausea, and 
 a diminished or capricious appetite, are often prominent symptoms 
 of early pregnancy, induced by the peculiar condition of the uterine 
 mucous membrane. 
 
 2d. Reflex actions taking place from the sensitive surfaces, through 
 the cerebro-spinal and sympathetic systems, to the involuntary muscles 
 and secreting organs. — Imprudent exposure of the integument to 
 cold and wet, will often bring on a diarrhoea. Mental and moral 
 impressions, conveyed through the special senses, will affect the 
 motions of the heart, and disturb the processes of digestion and 
 secretion. Terror, or an absorbing interest of any kind, will pro- 
 duce a dilatation of the pupil, and communicate in this way a pecu- 
 liarly wild and unusual expression to the eye. Disagreeable sights 
 or odors, or even unpleasant occurrences, are capable of hastening 
 or arresting the menstrual discharge, or of inducing premature 
 delivery. 
 
 3d. Refiex actions taking place through the sympathetic system from 
 one part of the internal organs to another. -^The contact of food with 
 the mucous membrane of the small intestine excites a peristaltic 
 
SYSTEM OF THE GREAT SYMPATHETIC. 4'25 
 
 movement in the muscular coat. The mutual action of the digestive, 
 urinary, and internal generative organs upon each other takes place 
 entirely through the medium of the sympathetic ganglia and their 
 nerves. The variations of the capillary circulation in different 
 abdominal viscera, corresponding with the state of activity or re- 
 pose of their associated organs, are to be referred to a similar 
 nervous influence. These phenomena are not accompanied by anv 
 consciousness on the part of the individual, nor by any apparent 
 intervention of the cerebro-spinal system. 
 
SECTION III. 
 HEPRODUCTION. 
 
 CHAPTER I. 
 
 ON THE NATURE OF REPRODUCTION, AND THE 
 ORIGIN OF PLANTS AND ANIMALS. 
 
 The process of reproduction is the most characteristic, and in 
 many respects the most interesting, of all the phenomena presented 
 by organized bodies. It includes the whole history of the changes 
 taking place in the organs and functions of the individual at suc- 
 cessive periods of life, as well as the production, growth, and de- 
 velopment of the new germs which make their appearance by 
 iieneration. 
 
 For all organized bodies pass through certain well defined epochs 
 or phases of development, by which their structure and functions 
 undergo successive alterations. We have already seen that the 
 living animal or plant is distinguished from inanimate substances 
 by the incessant changes of nutrition and growth which take place 
 in its tissues. The muscles and the mucous membranes, the osse- 
 ous and cartilaginous tissues, the secreting and circulatory organs, 
 all incessantly absorb oxygen and nutritious material from with- 
 out, and assimilate their molecules; while new substances, produced 
 by a retrogressive alteration and decomposition, are at the same 
 time excreted and discharged. These nutritive changes correspond 
 in rapidity with the activity of the other vital phenomena ; since 
 the production of these phenomena, and the very existence of the 
 vital functions, depend upon the regular and normal continuance 
 of the nutritive process. Thus the organs and tissues, which are 
 always the seat of this double change of renovation and decay, 
 retain nevertheless their original constitution, and continue to be 
 capable of exhibiting the vital phenomena. 
 
428 NATURE OF REPRODUCTIOISr. 
 
 The above changes, however, are not in reality the only ones 
 which talce place. For although the structure of the body and the 
 composition of its constituent parts appear to be maintained in an 
 unaltered condition, by the nutritive process, from one moment to 
 another, or from day to day, yet a comparative examination of 
 them at greater intervals of time will show that this is not pre- 
 cisely the case; but that the changes of nutrition are, in point of 
 fact, progressive as well as momentary. The composition and pro- 
 perties of the skeleton, for example, are not the same at the age of 
 twenty-five that they were at fifteen. At the latter period it con- 
 tains more calcareous and less organic matter than before ; and its 
 solidity is accordingly increased, while its elasticity is diminished. 
 Even the anatomy of the bones alters in an equally gradual manner; 
 the medullary cavities enlarging with the progress of growth, and 
 the cancellated tissue becoming more open and spongy in texture. 
 We have already noticed the difference in the quantity of oxygen 
 and carbonic acid inspired and exhaled at different ages. The 
 muscles, also, if examined after the lapse of some years, are found 
 to be less irritable than formerly, owing to a slow, but steady and 
 permanent deviation in their intimate constitution. 
 
 The vital properties of the organs, therefore, change with their 
 varying structure; and a time comes at last when they are per- 
 ceptibly less capable of performing their original functions than 
 before. This alteration being dependent on the varying activity of 
 the nutritive process, continues necessarily to increase. The very 
 exercise of the vital powers is inseparably connected with the sub- 
 sequent alteration of the organs employed in them ; and the func- 
 tions of life, therefore, instead of remaining indefinitely the same, 
 pass through a series of successive changes, which finally terminate 
 in their complete cessation. 
 
 The history of a living animal or plant is, therefore, a history of 
 successive epochs or phases of existence, in each of which the struc- 
 ture and functions of the body differ more or less from those in 
 every other. Every living being has a definite term of life, through 
 which he passes by the operation of an invariable law, and which, 
 at some regularly appointed time, comes to an end. The plant 
 germinates, grows, blossoms, bears fruit, withers, and decays. The 
 animal is born, nourished and brought to maturity, after which he 
 retrogrades and dies. The very commencement of existence, by 
 leading through its successive intermediate stages, conducts at last 
 necessarily to its own termination. 
 
NATURE OF REPRODUCTION. 429 
 
 But while individual organisms are thus constantly perishing and 
 disappearing from the stage, the particular kind, or species^ remains 
 in existence, apparently without any important change in the cha- 
 racter or appearance of the organized forms belonging to it. The 
 horse and the ox, the pine and the palm-tree, the different kinds of 
 wild and domesticated animals, even the different races of man 
 himself, have remained without any essential alteration ever since 
 the earliest historical epochs. Yet during this period innumerable 
 individuals, belonging to each species or race, must have lived 
 through their natural terin and successively passed out of existence. 
 A species may therefore be regarded as a type or class of organized 
 beings, in which the particular forms or structures composing it die 
 off constantly and disappear, but which nevertheless repeats itself 
 from year to year, and maintains its ranks constantly full by the 
 regular accession of new individuals. This process, by which new 
 organisms make their appearance, to take the place of those which 
 are destroyed, is known as the process of reproduction or generation. 
 Let us now see in what manner it is accomplished. 
 
 It has always been known that, as a general rule in the process 
 of generation, the young animals or plants are produced directly 
 from the bodies of the elder. The relation between the two is that 
 of parents and progeny ; and the new organisms, thus generated, 
 become in turn the parents of others who succeed them. For this 
 reason wherever such plants or animals exist, they indicate the 
 previous existence of others belonging to the same species; and if 
 by any accident the whole species should be destroyed in any par- 
 ticular locality, no new individuals could be produced there, unless 
 by the previous importation of others of the same kind. 
 
 The commonest observation shows this to be true in regard to 
 those animals and plants with whose history we are more familiarly 
 acquainted. An opinion, however, has sometimes been maintained 
 that there are exceptions to this rule ; and that living beings may, 
 under certain circumstances, be produced from inanimate substances, 
 without any similar plants or animals having preceded them ; pre- 
 senting, accordingly, the singular phenomenon of a progeny without 
 parents. Such a production of organized bodies is known by the 
 name oi spontaneous generation. It is believed by the large majority 
 of physiologists at the present day that no such spontaneous gene- 
 ration ever takes place; but that plants and animals are always 
 derived, by direct reproduction, from previously existing parents 
 of the same species. As this, however, is a question of some im- 
 
430 NATURE OF REPRODUCTION. 
 
 portance, and one which has been frequently discussed in works on 
 physiology, we shall proceed to pass in review the facts which have 
 been adduced in favor of the occurrence of spontaneous generation, 
 as well as those which would lead to its disproval and rejection. 
 
 It is evident, in the first place, that many apparent instances of 
 spontaneous generation are found to be of a very different character 
 so soon as they are subjected to a critical examination. Thus grass- 
 hoppers and beetles, earthworms and crayfish, the swarms of minute 
 insects that fill the air over the surface of stagnant pools, and even 
 frogs, moles, and lizards, have been supposed in former times to be 
 generated directly from the earth or the atmosphere ; and it was 
 only by investigating carefully the natural history of these animals 
 that they were ascertained to be produced in the ordinary manner 
 by generation from parents, and were found to continue the repro- 
 duction of their species in the same way. A still more striking 
 instance is furnished by the production of maggots in putrefying 
 meat, vegetables, flour paste, fermenting dung, &c. If a piece of 
 meat be exposed, for example, and allowed to undergo the process 
 of putrefaction, at the end of a few days it will be found to contain 
 a multitude of living maggots, which feed upon the decomposing 
 flesh. Now these maggots are always produced under the same 
 conditions of warmth, moisture and exposure, and at the same stage 
 of the putrefactive process. They are never to be found in fresh 
 meat, nor, in fact, in any other situation than the one just mentioned. 
 They appear, consequently, without any similar individuals having 
 existed in the same locality ; and considering the regularity of their 
 appearance under the given conditions, and their absence elsewhere, 
 it has been believed that they were spontaneously generated, under 
 the influence of warmth, moisture, and the atmosphere, from the 
 decaying organic substances. 
 
 A little examination, however, discovers a very simple solution 
 of the foregoing difficulty. On watching the exposed animal or 
 vegetable substances during the earlier periods of their decompo- 
 sition, it is found that flies and other insects, attracted by the odor 
 of the decaying material, hover round it and deposit their eggs 
 upon its surface or in its interior. These eggs, hatched by the 
 warmth to which they are exposed, produce the maggots ; which 
 are simply the young of the winged insects, and which after a time 
 become transformed, by the natural progress of development, into 
 perfect insects similar to their parents. The difficulty of account- 
 ing for the presence of the maggots by generation, therefore, de- 
 
IXFUSORIAL ANIMALCULES. 431 
 
 pended simply on the fact that thej were different in appearance 
 from the parents that produced them. This difference, however, is 
 merely a temporary one, corresponding with the difference in age, 
 and disappears when the development of the animal is complete ; 
 just as the young chicken, when recently hatched, has a different 
 form and plumage from those which it presents in its adult condi- 
 tion. 
 
 Nearly all the causes of error, in fact, which have suggested at 
 various times the doctrine of spontaneous generation, have been 
 derived from these two sources. First, the ready transportation of 
 eggs or germs, and their rapid hatching under favorable circum- 
 stances ; and secondly, the different appearances presented by the 
 same animal at different ages, in consequence of which the youthful 
 animal may be mistaken, by an ignorant observer, for an entirely 
 different species. These sources of error are, however, so readily 
 detected, as a general rule, by scientific investigation, that it is 
 hardly necessary to point out the particular instances in which they 
 exist. In fact, whenever a rare or comparatively unknown animal 
 or plant has been at any time supposed to be produced by sponta- 
 neous generation, it has only been necessary, for the most part, to 
 investigate thoroughly its habits and functions, to discover its secret 
 methods of propagation, and to show that they correspond, in all 
 essential particulars, with the ordinary laws of reproduction. The 
 limits, therefore, within which the doctrine of spontaneous genera- 
 tion can be applied, have been narrowed in precisely the same 
 degree that the study of natural history and comparative physiology 
 has advanced. At present, indeed, there remain but two classes 
 of phenomena which are ever supposed to lend any support to 
 the above doctrine; viz., the existence and production, 1st, of in- 
 fusorial animalcules, and 2d, of animal and vegetable parasites. 
 We shall now proceed to examine these two parts of the subject 
 in succession. 
 
 Infusorial Animalcules. — If water, holding in solution organic 
 substances, be exposed to the contact of the atmosphere at ordinary 
 temperatures, it is found after a short time to be filled with swarms 
 of minute living organisms, which are visible only by the micro- 
 scope. The forms of these microscopic animalcules are exceedingly 
 varied; owing either to the great number of species in existence, or to 
 their rapid alteration during the successive periods of their growth. 
 Ehrenberg has described more than 300 different varieties of them. 
 
432 
 
 NATUEE OF REPEODUCTION. 
 
 Diiferent kinds of Infusoria. 
 
 They are generally provided with cilia attached to the exterior of 
 their bodies, and are, for the most part, in constant and rapid motion 
 
 in the flaid which they inha- 
 ^'g- ^^1- bit. Owing to their presence 
 
 in animal and vegetable 
 watery infusions, they have 
 received the name of " infu- 
 soria," or " infusorial animal- 
 cules." 
 
 Now these infusoria are 
 always produced under the 
 conditions which we have de- 
 scribed above. The animal 
 or vegetable substance used 
 for the infusion may be pre- 
 viously baked or boiled, so 
 as to destroy all living germs 
 which it might accidentally 
 contain ; the water in which it is infused may be carefully distilled, 
 and thus freed from all similar contamination; and yet the infusorial 
 animalcules will make their appearance at the usual time and in the 
 usual abundance. It is only requisite that the infusion be exposed 
 to a moderately elevated temperature, and to the access of atmo- 
 spheric air ; conditions which are equally necessary for maintaining 
 the life of all animal and vegetable organisms, whatever be the 
 source from which they are derived. Under the above circum- 
 stances, therefore, either the animalcules must have been produced 
 by spontaneous generation in the watery infusion, or their germs 
 must have been introduced into it through the medium of the atmo- 
 sphere. No such introduction has ever been directly demonstrated, 
 nor have even any eggs or germs belonging to the infusoria ever 
 been detected. 
 
 Nevertheless, there is every probability that the infusoria are 
 produced from germs, and not by spontaneous generation. Since 
 the infusoria themselves are microscopic in size, it is not surprising 
 that their eggs, which must be smaller still, should have escaped 
 observation. We know, too, that in many instances the minute 
 germs of animals or plants may be wafted about in a dry state by 
 the atmosphere, until, by accidentally coming in contact with warmth 
 and moisture, they become developed and bring forth living organ- 
 isms. The eggs of the infusoria, accordingly, may be easily raised 
 
INFUSORIAL ANIMALCULES. 433 
 
 and held suspended in the atmosphere, under the form of minute 
 dust-like particles, ready to germinate and become developed when- 
 ever they are caught by the surface of a stagnant pool, or of any 
 artificially prepared infusion. In point of fact, the atmosphere 
 does really contain an abundance of such dust-like particles, even 
 when it appears to be most transparent and free from impurities. 
 This may be readily demonstrated by admitting a single beam of 
 sunshine into a darkened apartment, when the shining particles sus- 
 pended in the atmosphere become immediately visible in the track 
 of the sunbeam. Again, if a perfectly clean and polished mirror 
 be placed with its face upward in a securely closed room, and left 
 undisturbed for several days, its surface at the end of that time will 
 be found to be dimmed by the settling upon it of minute dust, 
 deposited from the atmosphere. There is no reason therefore for 
 disbelieving that the air may always contain a sufficient number of 
 organic germs for the production of infusorial animalcules. 
 
 There is some difficulty, however, in obtaining direct proof that it 
 is through the medium of the atmosphere that organic germs pene- 
 trate into the watery infusions. It is true that if such an infusion 
 be prepared from baked meat or vegetables and distilled water, and 
 afterward hermetically sealed, no infusoria are developed in it ; but 
 this only shows, as we have already intimated, that the free access 
 of air is necessary to the development of all organic life, just as it is 
 to the support of animals and plants under ordinary conditions of 
 growth and reproduction. Such a result, therefore, proves nothing 
 with regard to the external origin of the infusoria. In order to be 
 conclusive, such an experiment should be so contrived that the 
 watery infusion, previously freed from all foreign contamination, 
 should be supplied with a free access of atmospheric air, while the 
 introduction of living germs by this channel should at the same time 
 be rendered impossible. An experiment of this kind has in reality 
 been contrived and successfully carried out by Schultze, of Berlin.' 
 
 This observer prepared an infusion containing organic substances 
 in solution, and inclosed it in a glass flask (Fig. 152, a) of such a 
 size, that the infusion filled about one-half the entire capacity of the 
 vessel. The mouth of the flask was fitted with an air-tight stopper 
 provided with two holes, through which were passed narrow glass 
 tubes bent at right angles. To each of these tubes was attached a 
 potass apparatus (6, c), similar to those used for condensing carbonic 
 
 ' Edinburgh New Philosopliical Journal, Oct., 1837. 
 28 
 
434 
 
 NATUEE OF REPRODUCTION, 
 
 Schultze's experiment on Sponta- 
 XEODs Generation. — a Flask con 
 tainiug watery infusion. 6. Potass ap 
 paratus containing sulphuric acid, c 
 Potass apparatus containing caustic po 
 tass. 
 
 acid in organic analyses. One of these (a) was filled with concen- 
 trated sulphuric acid, the other {h) with a solution of caustic potass. 
 
 The flask with the organic infusion 
 having been subjected to a boiling 
 temperature, in order to destroy any 
 living germs which it might con- 
 tain, the stopper was inserted, and 
 the whole apparatus exposed to the 
 light, at the ordinary summer tempera- 
 ture. The connections of the apparatus 
 being perfectly tight, no air could pene- 
 trate into the flask, except by passing 
 tlirough either the sulphuric acid or 
 the potass; either of which would retain 
 and destroy any organic germs which 
 might be suspended in it. Every day 
 a fresh supply of air was introduced 
 into the flask by drawing it through 
 the tubas 5, c; and in this way the atmospheric air above the infu- 
 sion was constantly renewed, while at the same time the introduction 
 of living germs from without was effectually prevented. 
 
 Schultze kept this apparatus under his observation, as above, from 
 the last of May till the first of August; frequently examining the 
 edges of the fluid with a lens, through the sides of the glass jar, 
 but without ever detecting in it any traces of living organisms. At 
 the end of that period the flask was opened, and the fluid which it 
 contained subjected to direct examination, equally without result. 
 It was then exposed, in the same vessel and in the same situation 
 as before, to the free access of the atmosphere, and at the end of 
 two or three days it was found to be swarming with infusoria. 
 
 It is plain, therefore, that the infusoria cannot be regarded as 
 produced by spontaneous generation, but must be considered as 
 originating in the usual manner from germs; since they do not 
 make their appearance in the watery infusion, when the accidental 
 introduction of germs from without has been effectually prevented. 
 
 Animal and Vegetable Parasites. — This very remarkable 
 group of organized bodies is distinguished by the fact that they 
 live either upon the surface or in the interior of other animal or 
 vegetable organisms. Thus, the mistletoe fixes itself on the branches 
 of aged trees; the Oldium albicans vegetates upon the mucous sur- 
 
ANIMAL AND VEGETABLE PARASITES. 435 
 
 faces of the moiilh and pharynx ; the Botrytls Bassiana attacks the 
 body of the silkworm, and plants itself in its tissues; while many 
 species of trematoid icorms live attached to the gills of fish and of 
 water-lizards. 
 
 These parasites are usually nourished by the fluids of the animal 
 whose body they inhabit. Each particular species of parasite is 
 found to inhabit the body of a particular species of animal, and is 
 not found elsewhere. They are met with, moreover, as a general 
 rule, only in particular organs, or even in particular parts of a single 
 organ. Thus the Tricocephalus dispar is found only in the caecum ; 
 the Strongylus gigas in the kidney; the Distoma hepaticum in the 
 biliary passages. The Distoma variegatum is found only in the 
 lungs of the green frog, the Distoma cylindraceura in those of the 
 brown. The Teenia solium is found in the intestine of the human 
 subject in certain parts of Europe, while the Taenia lata occurs ex- 
 clusively in others. It appears, therefore, as though some local 
 combination of conditions were necessary to the production of these 
 parasites ; and they have been supposed, accordingly, to originate 
 by spontaneous generation in the localities where they are exclu- 
 sively known to exist. 
 
 A little consideration will "show, however, that the above condi- 
 tions are not, properly speaking, necessary or sufficient for the 
 production^ but only for the development of these parasites. All the 
 parasites mentioned above reproduce their species by generation. 
 They have male and female organs, and produce fertile eggs, often 
 in great abundance. The eggs contained in a single female Ascuris 
 are to be counted by thousands; and in a tapeworm, it is said, even 
 by millions. Now these eggs, in order that they may be hatched 
 and produce new individuals, require certain special conditions 
 which are favorable for their development; in the same manner 
 as the seeds of plants require, for their germination and growth, a 
 certain kind of soil and a certain supply of warmth and moisture. 
 It is accordingly no more surprising that the Ascaris vermicularix 
 should inhabit the rectum, and the Ascaris lumbricoides the ileum, 
 than that the Lobelia inflata should grow only in dry pastures, and 
 the Lobelia cardinalis by the side of running brooks. The lichens 
 flourish on the exposed surfaces of rocks and stone walls ; while 
 the fungi vegetate in darkness and moisture, on the decaying trunks 
 of dead trees. Yet no one imagines these vegetables to be spon- 
 taneously generated from the soil which they inhabit. The truth is 
 simply this, that if the animal or vegetable germ bs deposited in a 
 
436 NATURE OF KEPRODUCTION. 
 
 locality which affords the requisite conditions for its development, 
 it becomes developed; otherwise not. Each female Ascaris pro- 
 duces, as we have stated above, many thousands of ova. Now, 
 though the chances are very great against any particular one of 
 these ova being accidentally transported into the intestinal canal of 
 another individual, it is easy to see that there are many causes in 
 operation by which some of them might be so transported. By far 
 the greater number undoubtedly perish, from not meeting with the 
 conditions necessary for their development. One in a thousand, or 
 perhaps one in a million, is accidentally introduced into the body 
 of another individual, and consequently becomes developed there 
 into a perfect Ascaris. 
 
 The circumstance, therefore, that particular parasites are confined 
 to particular localities, presents no greater difficulty as to their 
 mode of reproduction, than the same fact regarding other animal 
 and vegetable organisms. 
 
 Neither is there any difficulty in accounting for the introduction 
 of parasitic germs into the interior of the body. The air and the 
 food offer a ready means of entrance into the respiratory and 
 digestive passages; and, a parasite once introduced into the intestine, 
 there is no difficulty in accounting for its presence in any of the 
 ducts leading from or opening into the alimentary canal. Some 
 parasites are known to insinuate themselves directly underneath 
 the surface of the skin ; as the Pulex penetrans or " chiggo" of 
 South America, and the Ixodes Americana or "tick." Others, 
 like the (Estrus bovis, penetrate the integument for the purpose of 
 depositing their eggs in the subcutaneous areolar tissue. Some 
 may even gain an entrance into the bloodvessels, and circulate in 
 this way all over the body. Thus the Filaria rubella is found alive 
 in the bloodvessels of the frog; and a species of Spiroptera in those 
 of the dog. It is easy to see, therefore, how, by such means, para- 
 sitic germs may be conveyed to any part of the body ; and may 
 even be deposited, by accidental arrest of the circulation, in the 
 substance of the solid organs. 
 
 The most serious difficulty, however, in the way of accounting 
 for the production of parasitic organisms, was that presented by the 
 existence of a class known as the encysted or sexless entpzoa. These 
 parasites for the most part occupy the interior of the solid organs 
 and tissues, into which they could not have gained access by the 
 mucous canals. Thus the Coenurus cerebralis is found imbedded 
 in the substance of the brain, the Trichina spiralis between the 
 
ANIMAL AND VEGETABLE PARASITES. 
 
 437 
 
 Trichina Spiralis; from rectus femoris mus- 
 cle of human subject. Magnified 57 diameters. i 
 
 fibres of the voluntary muscles, and the Cysticercus cellulosse in the 
 areolar tissue of various parts of the body. They are also distin- 
 guished from all other parasites by two peculiar characters. First, 
 they are inclosed in a distinct cyst, with which they have no organic 
 connection and from which they may be readily separated ; and se- 
 condlj'-, they have no genera- 
 tive organs, nor is there any Fig. 153. 
 apparent difference between 
 the sexes. The Trichina spi- 
 ralis, for example (Fig. 153), 
 is inclosed in an ovoid or 
 spindle-shaped cyst, swollen 
 in the middle and tapering at 
 each extremity, with a round- 
 ed cavity in its central por- 
 tion, in which the worm lies 
 
 coiled up in a spiral form. The worm itself has neither testicles 
 nor ovaries, nor does it present any trace of a sexual organization. 
 
 Now we have seen that it is easy to account for the conveyance 
 of these or any other parasites into the interior of vascular organs 
 and tissues; the eggs from which they are produced being trans- 
 ported by the bloodvessels to any part of the body, and there 
 retained by a lacal arrest of the capillary circulation. In the case 
 of the encysted entozoa, however, we have a much greater diffi- 
 culty; since these parasites are entirely without sexual organs or 
 generative apparatus of any sort, nor have they ever been dis- 
 covered in the act of producing eggs, or of developing in any 
 manner a progeny similar to themselves. It appears, accordingly, 
 difficult to understand how animals, which are without a sexual 
 apparatus, should have been produced by sexual generation. As 
 it is certain that they can have no progeny, it would seem equally 
 evident that they must have been produced without a parentage. 
 
 This difficulty, however, serious as it at first appears, is susceptible 
 of a very simple explanation. The case is in many respects analogous 
 to that of the maggots, hatched from the eggs of flies in putrefying 
 meat. These maggots are also without sexual organs ; for they 
 are still imperfectly developed, and in a kind of embryonic condi- 
 tion. It is only after their metamorphosis into perfect insects, that 
 generative organs are developed and a distinction between the 
 sexes manifests itself. This is, indeed, more or less the case with 
 all animals and with all vegetables. The blossom, which is the 
 
438 
 
 NATURE OF REPRODUCTION. 
 
 Fig. 154. 
 
 sexual apparatus of the plant, does not appear, as a general rule, 
 until the growth of the vegetable has continued for a certain time, 
 and it has acquired a certain age and strength. Even in the human 
 subject the sexual organs, though present at birth, are still very 
 imperfectly developed as to size, and altogether inactive in func- 
 tion. It is only later that these organs acquire their full growth, 
 and the sexual characters become complete. In very many of the 
 lower animals the sexual organs are entirely absent at birth, and 
 appear only at a later period of development. 
 
 Now the encysted or sexless entozoa are simply the undeveloped 
 young of other parasites which propagate by sexual generation ; 
 the detached membrane in which they are enveloped being either 
 the external membrane of the egg, not yet ruptured, or else an 
 adventitious cyst formed round the parasitic embryo. These 
 embryos have come, either accidentally, or in the natural course of 
 their migrations, to a situation which is not 
 suitable for their complete development. Their 
 development is accordingly arrested before it 
 arrives at maturity ; and the parasite never 
 reaches the adult condition, until removed from 
 the situation in which it has been placed, and 
 transported to a more favorable locality. 
 
 The above explanation has been demon- 
 strated to be the true one, more particularly 
 with regard to the Teenia, or tapeworm, and 
 several varieties of Cysticercus. The Taenia 
 (Fig. 154) is a parasite of which different species 
 are found in the intestine of the human subject, 
 the dog, cat, fox, and other of the lower animals. 
 Its upper extremity, termed the "head," con- 
 sists of a nearly globular mass, presenting upon 
 its lateral surfaces a set of four muscular disks, 
 or "suckers," and terminating anteriorly in a 
 conical projection which is provided with a 
 crown of curved processes or hooks, by which 
 the parasite attaches itself to the intestinal 
 mucous membrane. To this "head" succeeds 
 a slender ribbon-shaped neck, which is at first 
 smooth, but which soon becomes transversely 
 wrinkled, and afterward divided into distinct 
 rectangular pieces or "articulations." These 
 
ANIMAL AND VEGETABLE PARASITES. 
 
 439 
 
 articulations multiply by a process of successive growth or bud- 
 ding, from the wrinkled portion of the neck; and are constantly 
 removed farther and farther from their point of origin by new 
 ones formed behind them. As they gradually descend, by the 
 process of growth, farther down the body of the tapeworm, they 
 become larger &nd begin to exhibit a sexual apparatus, developed 
 in their interior. In each fully formed articulation there are con- 
 tained both male and female organs of generation ; and the mature 
 eggs, which are produced in great numbers, are thrown off to- 
 gether with the articulation itself from the lower extremity of the 
 tapeworm. Since the articulations are successively produced, as 
 we have mentioned above, by budding from the neck and the back 
 part of the head, the parasite cannot be effectually dislodged by 
 taking away any portion of the body, however large ; since it is 
 subsequently reproduced from the head, and continues its growth 
 as before. But if the head itself be removed from the intestine, no 
 further reproduction of the articulations can take place. 
 
 The Cysticercus is an encysted parasite, different varieties of which 
 are found in the liver, the peritoneum, and the meshes of the areolar 
 tissue in various parts of the body. It consists (Fig. 155), first, of 
 a globular sac, or cyst (a), which is not adherent to the tissues of 
 the organ in which the parasite is found, but may be easily sepa- 
 rated from them. In its interior is found another sac (6), lying 
 
 Fig. 155. 
 
 Fig. 156. 
 
 Cysticercus. — a. External cyst. 6. In- 
 tornal sac, coataining fluid c. Narrow canal, 
 furmed by involution of walls of sac, at the 
 bottom of which is the head of the tasuia. 
 
 Ctsticekcus, unfolded. 
 
 loose in the cavity of the former, and filled with a serous fluid. 
 This second sac presents, at one point upon its surface, a puckered 
 depression, leading into a long, narrow canal (c). This canal, which 
 is formed by an involution of the walls of the second sac, presents 
 at its bottom a small globular mass, like the head of the T^nia, 
 
440 NATURE OF REPRODUCTION. 
 
 provided with suckers and hooks, and supported upon a short 
 slender neck. If the outer investing sac be removed, the narrow 
 canal just described may be everted by careful manipulation, and 
 the parasite will then appear as in Fig. 156, with the head and neck 
 resembling those of a Taenia, but terminating behind in a dropsical 
 sac-like swelling, instead of the chain of articulations which are 
 characteristic of the fully formed tapeworm. 
 
 Now it has been shown, by the experiments of Kiichenmeister, 
 Siebold, and others, that the Cysticercus is only the imperfectly 
 developed embryo, or young of the T^nia. If the mature egg of 
 the Taenia be conveyed into the intestine of another animal of simi- 
 lar species, it hatches ; and the globular mass or head which is pro- 
 duced from it, after fixing itself to the mucous membrane, produces 
 the long, tape-like series of articulations, by the process of succes- 
 sive growth, or budding, already described. But if the same egg 
 find its way accidentally into the cellular tissue, the peritoneum, or 
 the liver, situations which are unnatural to it and unfavorable to 
 its development, it is not hatched. The head remains retracted 
 within the neck, as in Fig. 155, and still covered with the external 
 membrane of the egg, or investing cyst. 
 
 Prof. Siebold found the head of the Cysticercus fasciolaris, met 
 with in the liver of rats and mice, presenting so close a resem- 
 blance to the Taenia crassicollis, inhabiting the intestine of the cat, 
 that he was led to believe the two parasites to be identical. This 
 identity was, in fact, proved by the experiments of Kiichenmeister ; 
 and Siebold afterward demonstrated' the same relation to exist 
 between the Cysticercus pisiformis, found in the peritoneum of rab- 
 bits, and the Taenia serrata, from the intestine of the dog. This 
 experimenter succeeded in administering to dogs a quantity of the 
 cysticerci, fresh from the body of the rabbit, mixed with milk ; and 
 on killing the dogs, at various periods after the meal, from three 
 hours to eight weeks, he found the cysticerci in various stages of 
 development in the intestine, and finally converted into the full 
 grown Taenia, with complete articulations and mature eggs. 
 
 Dr. Kiichenmeister* has also performed the same experiment, with 
 success, on the human subject. A number of cysticerci were admi- 
 nistered to a criminal, at difi'erent periods before his execution, 
 
 ' In Buffalo Medical Journal, Feb. 1853 ; also in Siebold on Tape and Cystic 
 Worms, Sydenham translation : London, 1857, p. 59." 
 
 ^ On Animal and Vegetable Parasites, Sydenham Translation : London, 1857, 
 p. 115. 
 
ANIMAL AND VEGETABLE PARASITES, 441 
 
 varying from 12 to 72 hours; and upon post-mortem examination 
 of the body, no less than ten young tasniee were found in the 
 intestine, four of which could be distinctly recognized as specimens 
 of Taenia solium. 
 
 Finally, both Leuckart and Kiichenmeister' have shown, on the 
 other hand, that the eggs of Taenia solium, introduced into the body 
 of the pig, will give rise to the development of Cysticercus cellulosge; 
 thus demonstrating that the two kinds of parasites are identical in 
 their nature, and differ only in the manner and degree of their 
 development. 
 
 There remains, accordingly, no good reason for believing that 
 even the encysted parasites are produced by spontaneous genera- 
 tion. Whatever obscurity may hang round the origin or reproduc- 
 tion of any class or species of animals, the direct investigations of 
 the physiologist always tend to show that they do not^ in reality, 
 form any exception to the general law in this respect; and the only 
 opinion which is admissible, from the facts at present within our 
 knowledge, is that organized beings^ animal and vegetable^ ivherever they 
 may be found, are always the progeny of previously existing parents. 
 
 ' Op cit., p. 120. 
 
442 
 
 SEXUAL GENEEATION. 
 
 CHAPTER II. 
 
 ON SEXUAL GENERATION, AND THE MODE OF ITS 
 ACCOMPLISHMENT. 
 
 Fig. 157. 
 
 The function of generation is performed by means of two sets of 
 organs, each of which gives origin to a peculiar product, capable of 
 uniting with the other so as to produce a new individual. These 
 
 two sets of organs, belonging to the 
 two different sexes, are called the male 
 and female organs of generation. The 
 female organs produce a globular body 
 called the germ^ or egg^ which is capable 
 of being developed into the body of 
 the young animal or plant ; the male 
 organs produce a substance which is 
 necessary to fecundate the germ, and 
 enable it to go through with its natural 
 growth and development. 
 
 Such are the only essential and uni- 
 versal characters of the organs of gene- 
 ration. These organs, however, exhibit 
 various additions and modifications in 
 different classes of organized beings, 
 while they show throughout the same 
 fundamental and essential characters. 
 
 In the flowering plants, for example, 
 the blossom, which is the generative 
 apparatus (Fig. 157), consists first of a 
 female organ containing the germ (a), situated usually upon the 
 highest part of the leaf-bearing stalk. This is surmounted by a 
 nearly straight column, termed the pistil (6), dilated at its summit 
 into a globular expansion, and occupying the centre of the flower. 
 Around it are arranged several slender filaments, or stamens, bear- 
 ing upon their extremities the male organs, or anthers (c, c). The 
 
 Blossom op Convolvuhts 
 PtruPDREUS. (Morniug glory.) — a. 
 Gorni. 6. Pistil, c, c. Stamen.s, witli 
 anthers, d. Corolla e. Calyx 
 
SEXUAL GENERATION. 
 
 443 
 
 whole is surrounded by a circle or crown of delicate and brilliantly 
 colored leaves, termed the corolla {d), which is frequently provided 
 with a smaller sheath of green leaves outside, called the calyx (e). 
 The anthers, when arrived at maturity, discharge a fine organic 
 dust, called the pollen, the granules of which are caught upon the 
 extremity of the pistil, and then penetrate downward through its 
 tissues, until they reach its lower extremity and come in contact 
 with the germ. The germ thus fecundated, the process of genera- 
 tion is accomplished. The pistil, anthers, and corolla wither and 
 fall off, while the germ increases rapidly in size, and changes in 
 form and texture, until it ripens into the mature fruit or seed. It 
 is then ready to be separated from the parent stem ; and, if placed 
 in the proper soil, will germinate and at last produce a new plant 
 similar to the old. 
 
 In the above instance, the male and female organs are both 
 situated upon the same flower; as in the lily, the violet, the con- 
 volvulus, &c. In other cases, there are separate male and female 
 flowers upon the same plant, of which the male flowers produce 
 only the pollen, the female, the 
 
 germ and fruit. In others still, Fig- 158. 
 
 the male and female flowers are 
 situated upon different plants, 
 which otherwise resemble each 
 other, as in the willow, poplar, 
 and hemp. 
 
 In animals, the female organs 
 of generation are called ovaries^ 
 since it is in them that the egg, 
 or "ovum," is produced. The 
 male organs are the testicles^ 
 which give origin to the fecun- 
 dating product, or "seminal 
 fluid," by which the egg is fer- 
 tilized. We have already men- 
 tioned above that in the articula- 
 tions of the tapeworm the ovaries 
 and. testicles are developed to- 
 gether. (Fig. 158.) The ovary 
 
 (a, a, a) is a series of branching follicles terminating in rounded 
 extremities, and communicating with each other by a central canal. 
 The testicle {h) is a narrow, convoluted tube, very much folded 
 
 \s. 
 
 , ^^>^ 1 " 
 
 fevl. 
 
 ^ 
 
 
 ■^^•s I 
 
 '■^T^ 
 
 -^":3 \ 
 
 =.-•" = 
 
 - ^-, \ 
 
 @- 
 
 ' \ 
 
 '^^^rrroiri^ 
 
 _ \ 
 
 
 Single A h t i c u i, a t i o x of T .b n i a 
 Crassicoi, I, IS, from small intestino of cat. — 
 a, a, a. Ovary filled with eggs. b. Testicle, c. 
 Geaital orifice. 
 
444 SEXUAL GENERATION. 
 
 upon itself, which opens by an external orifice (c) upon the lateral 
 border of the articulation, about midway between its two ex- 
 tremities. The spermatic fluid produced in the testicle is intro- 
 duced into the female generative passage, which opens at the same 
 spot, and, penetrating deeply into the interior, comes in contact 
 with the eggs, which are thereby fecundated and rendered fertile. 
 The fertile eggs are afterward set free by the rupture or decay of 
 the articulation, and a vast number of young produced by their 
 development. 
 
 In snails, also, and in some other of the lower animals, the ovaries 
 and testicles are both present in the same individual ; so that these 
 animals are sometimes said to be " hermaphrodite," or of double 
 sex. In realit}^, however, it appears that the male and female 
 organs do not come to maturity at the same time; but the ovaries 
 • are first developed and perform their function, after which the tes- 
 ticles come into activity in their turn. The same individual, there- 
 fore, is not both male and female at any one time ; but is first 
 female and afterward male, exercising the two generative functions 
 at different ages. 
 
 In all the higher animals, however, the two sets of generative 
 organs are located in separate individuals; and the species is 
 consequently divided into two sexes, male and female. All that 
 is absolutely requisite to constitute the two sexes is the existence 
 of testicles in the one, and of ovaries in the other. Beside these, 
 however, there are, in most instances, certain secondary or acces- 
 sory organs of generation, which assist more or less in the accom- 
 plishment of the process, and which occasion a greater difference 
 in tlie anatomy of the two sexes. Suet are the uterus and mam- 
 mary glands of the female, the vesiculse seminales and prostate 
 of the male. The female naturally having the immediate care of 
 the young after birth, and the male being occupied in providing 
 food and protection for both, there are also corresponding differ- 
 ences in the general structure of the body, which affect the whole 
 external appearance of the two sexes, and which even show them- 
 selves in their mental and moral, as well as in their physical 
 characteristics. In some cases this difference is so excessive that 
 the male and female would never be recognized as belonging to the 
 same species, unless they were seen in company with each other. 
 Not to mention some extreme instances of this among insects and 
 other invertebrate animals, it will be sufficient to refer to the well 
 known examples of the cock and the hen, the lion and lioness, the 
 
SEXUAL GENERATION". 445 
 
 buck and the doe. In the human species, also, the distinction 
 between the sexes shows itself in the mental constitution, the dis- 
 position, habits, and pursuits, as well as in the general conforma- 
 tion of the body, and the peculiarities of external appearance. 
 
 We shall now study more fully the character of the male and 
 female organs of generation, together with their products, and the 
 manner in which these are discharged from the body, and brought 
 into relation with each other. 
 
446 
 
 EGG AND FEMALE ORGANS OF GENERATION. 
 
 CHAPTER III. 
 
 ON THE EGG, AND THE FEMALE ORGANS OF 
 GENERATION. 
 
 The egg is a globular body which varies considerably in size in 
 different classes of animals, according to the peculiar conditions 
 under which its development is to take place. In the frog it mea- 
 sures yig of an inch, in the lamprey g'g, in quadrupeds and in the 
 human species y|(^. It consists, first, of a membranous external 
 sac or envelope, the vitelline membrane; and secondly, of a spherical 
 mass inclosed in its interior, called the vitellus. 
 
 The vitelline membrane in birds and reptiles is very thin, measur- 
 ing often not more than tsoct) of an inch in thickness, and is at the 
 
 same time of a somewhat fibrous texture, 
 ^^g- ^^^- In man and the higher animals, on the 
 
 contrary, it is perfectly smooth, structure- 
 less and transparent, and is about ^^^-q of 
 an inch in thickness. Notwithstanding 
 its delicate and transparent appearance, it 
 has a considerable degree of resistance 
 and elasticity. The egg of the human 
 subject, for example, may be perceptibly 
 flattened out under the microscope by 
 pressing with the point of a needle upon 
 the slip of glass which covers it; but it 
 still remains unbroken, and when the 
 pressure is removed, readily resumes its globular form. When the 
 egg is somewhat flattened under the microscope in this way, by 
 pressure of the glass slip, the apparent thickness of the vitelline 
 membrane is increased, and it then appears (Fig. 159) as a rather 
 wide, colorless, and pellucid border or zone, surrounding the granu- 
 lar and opaque vitellus. Owing to this appearance, it has some- 
 times received the name of the "zona pellucida." The name of 
 vitelline membrane, however, is the one more generally adopted, 
 and is also the more appropriate of the two. 
 
 Human Ovum, magnified S.3 
 diameters, a. Virelline mpmbrane. 
 h. Vitellus. c. Genniuative vesicle. 
 d. Germinative spot. 
 
EGG AND FEMALE ORGANS OF GENERATION. 447 
 
 The vilellus {h), is a globular, semi-solid mass, contained within 
 the vitelline membrane. It consists of a colorless albuminoid sub- 
 stance, with an abundance of minute molecules and oleaginous 
 granules scattered through it. These minute oleaginous masses 
 give to the vitellus a partially opaque and granular aspect under 
 the microscope. Imbedded in the vitellus, usually near its surface 
 and almost immediately beneath the vitelline membrane, there is a 
 clear, colorless, transparent vesicle (c) of a rounded form, known 
 as the germinative vesicle. In the egg of the human subject and of 
 the quadrupeds, this vesicle measures ggo to g J^ of an inch in 
 diameter. It presents upon its surface a 
 dark spot, like a nucleus {d), which is known ^'S* ^'^^' 
 
 by the name of the germinative spot. The 
 germinative vesicle, with its nucleus-like 
 spot, is often partially concealed by the 
 granules of the vitellus by which it is sur- 
 rounded, but it may always be discovered 
 by careful examination. 
 
 If the egg be ruptured by excessive pres- human ovum, luptmed ly 
 
 , , . , . ,, . pressure; showing the vitellus 
 
 sure under the, microscope, the vitellus is partially expelled, the germlnu- 
 
 seen to have a gelatinous consistency. It '*'<^ ''^^'c'e at «, and the smooth 
 
 . fracture of the vitelline mem- 
 
 is gradually expelled from the vitelline brane. 
 cavity, but still retains the granules and oil 
 
 globules entangled in its substance. (Fig. 160.) The edges of the 
 fractured vitelline membrane, under these circumstances, present a 
 smooth and nearly straight outline, without any appearance of 
 laceration or of a fibrous structure. The membrane is, to all ap- 
 pearance, perfectly homogeneous. 
 
 The most essential constituent of the egg is the vitellus. It is 
 from the vitellus that the body of the embryo will afterward be 
 formed, and the organs of the new individual developed. The 
 vitelline membrane is merely a protective inclosure, intended to 
 jirotect the vitellus from injury, and enable it to retain its figure 
 during the ea:rly periods of development. 
 
 The egg, as above described, consists therefore of a simple 
 vitellus of minute size, and a vitelline membrane inclosing it. It 
 is such an egg which is found in the human subject, the quadru- 
 peds, most aquatic reptiles, very many fish, and some invertebrate 
 jinimals. In nearly all those species, in fact, where the fecundated 
 eggs are deposited and hatched in the water, as well as those in 
 which they are retained in the body of the female until the develop- 
 
448 EGa AND FEMALE ORGANS OF GENERATION. 
 
 merit of the young is completed, such an egg as above described is 
 sufficient for the formation of the embryo; since during its develop- 
 ment it can absorb freely, either from the water in which it floats, 
 or from the mucous membrane of the female generative organs, the 
 requisite supply of nutritious fluids. But in birds and in the 
 terrestrial reptiles, such as lizards, tortoises, &c., where the eggs 
 are expelled from the body of the female at an early period, and 
 incubated on land, there is no external source of nutrition, to pro- 
 vide for the support of the young animal during its development. 
 In these instances accordingly the vitellus, or "yolk," as it is called, 
 is of very large size; and the bulk of the egg is still further in- 
 creased by the addition, within the female generative passages, of 
 layers of albumen and various external fibrous and calcareous 
 envelopes. The essential constituents of the egg, however, still 
 remain the same in character, and the process of embryonic develop- 
 ment follows the same general laws as in other cases. 
 
 The eggs are produced in the interior of certain organs, situated 
 in the abdominal cavity, called the ovaries. These organs consist 
 of a number of globular sacs, or follicles, known as the "Graafian 
 follicles," each one of which contains a single egg. The follicles 
 are connected with each other by a quantity of vascular areolar 
 tissue, which binds them together into a well defined and consistent 
 mass, covered upon its exterior by a layer of peritoneum. The 
 egg has sometimes been spoken of as a " product," or even as a 
 " secretion" of the ovary. Nothing can be more inappropriate, 
 however, than to compare the egg with a secretion, or to regard the 
 ovary as in any respect resembling a glandular organ. The egg is 
 simply an organized body, growing in the ovary like a tooth in its 
 follicle, and forming a constituent part of the body of the female. 
 It is destined to be finally separated from its attachments and thrown 
 off; but until that time, it is, properly speaking, a part of the 
 ovarian texture, and is nourished like any other portion of the 
 female organism. 
 
 The ovaries, accordingly, since they are directly concerned in 
 the production of the eggs, are to be regarded as the essential 
 parts of the female generative apparatus. Beside them, however, 
 there are usually present certain other organs, which play a secon- 
 dary or accessory part in the process of generation. The most 
 important of these accessory organs are two symmetrical tubes, or 
 oviducts, which are destined to receive the eggs at their internal 
 extremity and convey them to the external generative orifice. The 
 
EGG AND FEMALE ORGANS OF GENERATION. 
 
 449 
 
 mucous membrane lining the oviducts is also intended to supply 
 certain secretions during the passage of the egg, which are requi- 
 site either to complete its structure, or to provide for the nutrition 
 of the embryo. 
 
 In the frog, for example, the oviduct commences at the upper 
 part of the abdomen by a rather wide orifice, which communicates 
 directly with the peritoneal cavity. It 
 soon after contracts to a narrow tube, 
 and pursues a zigzag course down the 
 side of the abdomen (Fig. 161), folded 
 upon itself in convolutions, like the 
 small intestine, until it opens, near its 
 fellow of the opposite side, into the 
 "cloaca," or lower part of the intestinal 
 canal. The oviducts present the same 
 general characters with those described 
 above, in nearly all species of reptiles 
 and birds ; though there are some modi- 
 fications, in particular instances, which 
 do not require any special notice. 
 
 The ovaries, as well as the egg which 
 they contain, undergo at particular sea- 
 sons a periodical development or increase 
 in growth. If we examine the female 
 frog iti the latter part of summer or the 
 fall, we shall find the ovaries presenting 
 
 the appearance of small clusters of minute and nearly colorless 
 eggs, the smaller of which are perfectly transparent and not over 
 y^o of an inch in diameter. But in the early spring, when the 
 season of reproduction approaches, the ovaries will be found in- 
 creased to four or five times their former size, and forming large 
 lobulated masses, crowded with dark-colored opaque eggs, measur- 
 ^i''g T-2 of ^^ ii^ch in diameter. At the approach of the generative 
 season, in all the lower animals, a certain number of the eggs, which 
 were previously in an imperfect and inactive condition, begin to in- 
 crease in size and become somewhat altered in structure. The vitel- 
 lus more especially, which was before colorless and transparent, 
 becomes granular in texture as well as increased in volume ; and 
 assumes at the same time, in many species of animals, a black, 
 brown, yellow, or orange color. In the human subject, however, 
 29 
 
 Female Generative Or- 
 gans OF Frog. — a, a Ovaries. 
 b, b. Oviducts, e, c. Tlieir intertiiil 
 oi-ifices. d. Cloaca, shovviug exter- 
 nal orifices of oviducts. 
 
450 EGG AND FEMALE ORGANS OF GENERATION. 
 
 the change consists only in an increase of size and granulation, 
 without any remarkable alteration of color. 
 
 The eggs, as they ripen in this way, becoming enlarged and 
 changed in texture, gradually distend the Graafian follicles and 
 project from the surface of the ovary. At last, when fully ripe, 
 they are discharged by a rupture of the walls of the follicles, and, 
 passing into the oviducts, are conveyed by them to the external 
 generative orifice, and there expelled. In this way, as successive 
 seasons come round, successive crops of eggs enlarge, ripen, leave 
 the ovaries, and are discharged. Those which are to be expelled 
 at the next generative epoch may always be recognized by their 
 greater degree of development; and in this way, in many animals, 
 the eggs of no less than three different crops may be recognized in 
 the ovary at once, viz., 1st, those which are perfectly mature and 
 ready to be discharged ; 2d, those which are to ripen in the follow- 
 ing season ; and 3d, those which are as yet altogether inactive and 
 undeveloped. In most fish and reptiles, as well as in birds, this 
 regular process of maturation and discharge of eggs takes place 
 but once a year. In different species of quadrupeds it may take 
 place annually, semi-annually, bimonthly, or even monthly; but 
 in every instance it recurs at regular intervals, and exhibits accord- 
 ingly, in a marked degree, the periodic character which we have 
 seen to belong to most of the other vital phenomena. 
 
 Action of the Oviducts and Female Generative Passages. — In frogs 
 and lizards, the ripening and discharge of the eggs take place, as 
 above mentioned, in the early spring. At the time of leaving the 
 ovary, the eggs consist simply of the dark colored and granulnr 
 vitellus, inclosed in the vitelline membrane. They are then received 
 by the inner extremity of the oviducts, and carried downward by 
 the peristaltic movement of these canals, aided by the more power- 
 ful contraction of the abdominal mus- 
 Fig. 162. cles. During the passage of the eggs, 
 
 moreover, the mucous membrane of 
 the oviduct secretes a colorless, viscid, 
 
 %*• (® " * ^ -< albuminoid substance, which is depo- 
 
 •® ^-7 ^-V**) sited in successive layers round each 
 
 » %ti^ ggg^ forming a thick and tenacious 
 
 Mature Frogs' eogs.-«. While coating or envclopc. (Fig. 162.) When 
 «tiii in the ovary. 6. After passing ^^^ ^^^ finally discharged, this 
 
 through the oviduct. OO . -^ o ' 
 
 albuminoid matter absorbs the water 
 in which the spawn is deposited, and swells up into a transparent 
 
EGG AND FEMALE ORGANS OF GENERATION. 451 
 
 gelatinous mass, in which the eggs are separately imbedded. This 
 substance supplies, by its subsequent liquefaction and absorption, 
 a certain amount of nutritious material, during the development 
 and early growth of the embryo. 
 
 In the terrestrial reptiles and in birds, the oviducts perform a 
 still more important secretory function. In the common fowl, the 
 ovary consists, as in the frog, of a large number of follicles, loosely 
 connected by areolar tissue, in which the eggs can be seen in different 
 stages of development. (Fig, ld3, a.) As the egg which is approach- 
 ing maturity enlarges, it distends the cavity of its follicle and pro- 
 jects farther from the general surface of the ovary; so that it hangs 
 at last into the peritoneal cavity, retained only by the attenuated 
 wall of the follicle, and a slender pedicle through which run the 
 bloodvessels by which its circulation is supplied. A rupture of the 
 follicle then occurs, at its most prominent part, and the egg is dis- 
 charged from the lacerated opening. 
 
 At the time of its leaving the ovary, the egg of the fowl consists 
 of a large, globular, orange-colored vitellus, or " yolk," inclosed in 
 a thin and transparent vitelline membrane. Immediately under- 
 neath the vitelline membrane, at one point upon the surface of tlie 
 vitellus, is a round white spot, consisting of a layer of minute 
 granules, termed the ''cicatricula." It is in the central part of the 
 cicatricula that the germinative vesicle is found imbedded, at an 
 early stage of the development of the egg. At the time of its 
 discharge from the ovary, the germinative vesicle has usually dis- 
 appeared ; but the cicatricula is still a very striking and important 
 part of the vitellus, as it is from this spot that the body of the chick 
 begins afterward to be developed. 
 
 At the same time that the egg protrudes from the surface of the 
 ovary, it projects into the inner orifice of the oviduct ; so that; when 
 discharged from its follicle, it is immediately embraced by the upper 
 or fringed extremity of this tube, and commences its passage down- 
 ward. In the fowl, the muscular coat of the oviduct is highly deve- 
 loped, and its peristaltic contractions gently urge the egg from above 
 downward, precisely as the oesophagus or the intestines transport the 
 food in a similar direction. While passing through the first two or 
 three inches of the oviduct (c, <i), where the mucous membrane is 
 smooth and transparent, the yolk merely absorbs a certain quantity 
 of fluid, so as to become more flexible and yielding in consistency. 
 It then passes into a second division of the generative canal, in 
 which the raucous membrane is thick and glandular in texture, and 
 
452 EGG AND FEMALE ORGANS OF GENERATION. 
 
 •is also thrown into numerous longitudinal folds, which project into 
 the cavity of the oviduct. This portion of the oviduct (o?, e) extends 
 over about nine inches of its entire length. In its upper part, the 
 mucous membrane secretes a viscid material, by which the yolk is 
 encased, and which soon consolidates into a gelatinous, membranous 
 deposit; thus forming a second homogeneous layer, outside the 
 vitelline membrane. 
 
 Now the peristaltic movements of this part of the oviduct are 
 such as to give a rotatory, as well as a progressive motion to the 
 egg ; and the two extremities of the membranous layer described 
 above become, accordingly, twisted, in opposite directions, into two 
 fine cords, which run backward and forward from the opposite poles 
 of the egg. These cords are termed the "chalazte," and the membrane 
 with which they are connected, the " chalaziferous membrane." 
 
 Throughout the remainder of the second division of the oviduct, 
 the mucous membrane exudes an abundant, gelatinous, albuminoid 
 substance, which is deposited in successive layers round the yolk, 
 inclosing at the same time the chalaziferous membrane and the 
 chalazee. This substance, which forms the so-called albumen, or 
 " white of egg," is semi-solid in consistency, nearly transparent, and 
 of a faint amber color. It is deposited in greater abundance in front 
 of the advancing Qgg than behind it, and forms accordingly a 
 pointed or conical projection in front, while behind, its outline is 
 rounded off, parallel with the spherical surface of the yolk. In this 
 way, the egg acquires, when covered with its albumen, an ovoid 
 form, of which one end is round, the other pointed ; the pointed 
 extremity being always directed downward, as the egg descends 
 along the oviduct. 
 
 In the third division of the oviduct (/), which is about three and 
 a half inches in length, the mucous membrane is arranged in longi- 
 tudinal folds, which are narrower and more closely packed than in 
 the preceding portion. The material secreted in this part, and de- 
 posited upon the egg^ condenses into a firm fibrous covering, com- 
 posed of three different layers which closely embrace the surface 
 of the albuminous mass, forming a tough, flexible, semi-opaque 
 envelope for the whole. These layers are known as the external, 
 middle, and internal fibrous membranes of the egg. 
 
 Finally the egg passes into the fourth division of the oviduct [g)^ 
 which is wider than the rest of the canal, but only a little over two 
 inches in length. Here the mucous membrane, which is arranged 
 in abundant, projecting, leaf-like villosities, exudes a fluid very rich 
 
EGG AND FEMALE ORGANS OF GENERATION. 
 
 453 
 
 in calcareous salts. The most external of the three membranes 
 just described is permeated by this fluid, and very soon the calcare- 
 ous matter begins to crystallize in the interstices of its fibres. This 
 deposit of calcareous matter goes on, growing constantly thicker 
 and more condensed, until the entire 
 external membrane is converted into Fig. 163. 
 
 a white, opaque, brittle, calcareous 
 shell, which incloses the remaining 
 portions and protects them from ex- 
 ternal injury. The egg is then driven 
 outward by the contraction of the 
 muscular coat through a narrow por- 
 tion of the oviduct (A), and, gradually 
 dilating the passages by its conical 
 extremity, is finally discharged from 
 the external orifice. 
 
 The egg of the fowl, after it has 
 been discharged from the body, con- 
 sists, accordingly, of various parts; 
 some of which, as the yolk and the 
 vitelline membrane, entered into its 
 original formation, while the remain- 
 der have been deposited round it dur- 
 ing its passage through the oviduct. 
 On examining such an egg (Fig. 164), 
 we find externally the calcareous 
 shell (/i), while immediately beneath 
 it are situated the middle and internal 
 fibrous shell-membranes (e,/). 
 
 Soon after the expulsion of the egg 
 there is a partial evaporation of its 
 watery ingredients, which are replaced 
 by air penetrating through the pores 
 of the shell at its rounded extremity. 
 The air thus introduced accumulates 
 between the middle and internal 
 fibrous membranes at this spot, sepa- 
 
 Female Generative Organs o* Fowl —a. Ovary. 6. Graafian vesicle, from which (he 
 egg has j ust been discharged, c. Yolk, entering upper extremity of oviduct, d, e. Second division 
 of oviduct, in vrhich chalaziferous membrane, chalazje, and albumen are formed. /. Third portion, 
 in which the fibrous shell membranes are produced, ff. Fourth portion laid open, showing egg com- 
 pletely formed, with calcareous shell, h. Narrow canal through which the egg is dlt^charged. 
 
454 
 
 EGG AND FEMALE ORGANS OF GENERATION. 
 
 rating them from each other, and forming a cavity or air-chamber 
 {g\ which is always found between the two fibrous membranes at 
 the rounded end of the egg. Next we come to the albumen or 
 " white" of the egg {d) ; next to the chalaziferous membrane and 
 chalazae (c); and finally to the vitelline membrane {h) inclosing the 
 
 Fig. 164. 
 
 Diagram of Fowl' s Egg. — a. Yolk. b. Vitelline membrane, c. Chalaziferous membrane, d. 
 Albumen, e. f Middle and internal shell membranes, g. Air-chamber, h. Calcareous shell. 
 
 yolk (a). After the expulsion of the egg, the external layers of the 
 albumen liquefy ; and the vitellus, being specifically lighter than 
 the albumen, owing to the large proportion of oleaginous matter 
 which it contains, rises toward the surface of the egg, with the cica- 
 tricula uppermost. This part, therefore, presents itself almost im- 
 mediately on breaking open the egg upon its lateral surface, and is 
 placed in the most favorable position for the action of warmth and 
 atmospheric air in the development of the chick. 
 
 The vitellus, therefore, is still the essential and constituent portion 
 of the egg; while all the other parts consist either of nutritious mate- 
 rial, like the albumen, provided for the support of the embryo, or 
 of protective envelopes, like the shell and the fibrous membranes. 
 
 In the quadrupeds, another and still more important modification 
 of the oviducts takes place. In these animals, the egg, which is 
 originally very minute in size, is destined to be retained within the 
 generative passages of the female during the development of the 
 embryo. While the upper part of the oviduct, therefore, is quite 
 narrow, and intended merely to transmit the egg from the ovary, 
 and to supply it with a little albuminous secretion, its lower por- 
 tions are very much increased in size, and are lined, moreover, with 
 
EGG AND FEMALE ORGANS OF GENERATION. 
 
 455 
 
 a mucous membrane, so constructed as to provide for the protection 
 and nourishment of the embryo, during the entire period of gesta- 
 tion. The upper and narrower portions of the oviduct are known 
 as the "Fallopian tubes" (Fig. 165); while the lower and more 
 
 Fig. 165. 
 
 Utkri-s and Ovaries of thr Sow. — a, n. Ovaries. h,h. Fallopiau tubes, c, c. Horns of 
 uterus, d. Body of uterus, e. Vagiua. 
 
 highly developed portions constitute the uterus. These lower por- 
 tions unite with each other upon the median line near their infe- 
 rior termination, so as to form a central organ, termed the " body" 
 of the uterus; while the remaining ununited parts are known as 
 its "cornua," or "horns." 
 
 In the human subject, the female generative apparatus presents 
 the following peculiarities. The ovaries consist of Graafian follicles, 
 which are imbedded in a somewhat dense areolar tissue, supplied 
 with an abundance of bloodvessels. The entire mass is covered 
 with a thick, opaque, yellowish-white layer of fibrous tissue, called 
 the "albuglneous tunic." Over the whole is a layer of peritoneum, 
 which is reflected upon the vessels which supply the ovary, and is 
 continuous with the broad ligaments of the uterus. 
 
 The oviducts commence by a wide expansion, provided with 
 fringed edges, called the " fimbriated extremity of the Fallopian 
 tube." The Fallopian tubes themselves are very narrow and con- 
 voluted, and terminate on each side in the upper part of the body 
 of the uterus. In the human subject, the body of the uterus is so 
 much developed at the expense of the cornua, that the latter hardly 
 appear to have an existence; and in fact no trace of them is visible 
 externally. But on opening the body of the uterus its cavity is 
 seen to be nearly triangular in shape, its two superior angles run- 
 ning out on each side to join the lower extremities of the Fallopian 
 tabes. This portion evidently consists of the cornua, which .have 
 
456 
 
 EGG AND FEMALE ORGANS OF GENERATION. 
 
 been consolidated with the body of the uterus, and enveloped in 
 its thickened layer of muscular fibres. 
 
 Fig. 166. 
 
 Generative Organs of He; man Female. — a, a. Ovaries. 6, 6. Fallopian tubes, 
 e. Body of uterus, d. Cervix, e. Vagiua. 
 
 The cavity of the body of the uterus terminates below by a con- 
 stricted portion termed the os internum, by which it is separated 
 from the cavity of the cervix. These two cavities are not only 
 different from each other in shape, but differ also in the structure 
 of their mucous membrane and the functions which it is destined 
 to perform. 
 
 The mucous membrane of the body of the uterus in its usual 
 condition is smooth and rosy in color, and closely adherent to the 
 subjacent muscular tissue. It consists of minute tubular follicles 
 somewhat similar to those of the gastric mucous membrane, ranged 
 side by side, and opening by distinct orifices upon its free surface. 
 The secretion of these follicles is destined for the nutrition of the 
 embryo during the earlier periods of its formation. 
 
 The internal surface of the neck of the uterus, on the other hand, 
 is raised in prominent ridges, which are arranged usually in two 
 lateral sets, diverging from a central longitudinal ridge; presenting 
 the appearance known as the "arbor Yitsa uterina." The follicles 
 of this part of the uterine mucous membrane are different in struc- 
 ture from those of the foregoing. They are of a globular or sac- 
 like form, and secrete a very firm, adhesive, transparent mucus, 
 which is destined to block up the cavity of the cervix during ges- 
 
EGG AND FEMALE ORGANS OF GENERATION. 457 
 
 tation, and guard against the accidental displacement of the egg. 
 Some of these follicles are frequently distended with their secretion, 
 and project, as small, hard, rounded eminences, from the surface 
 of the mucous membrane. In this condition they are sometimes 
 designated by the name of " ovula Nabothi," owing to their having 
 been formerly mistaken for eggs, or ovules. 
 
 The cavity of the cervix uteri is terminated below by a second 
 constriction, the "os externum." Below this comes the vagina, 
 which constitutes the last division of the female generative pas- 
 sages. 
 
 The accessory female organs of generation consist therefore of 
 ducts or tubes, by means of which the egg is conveyed from within 
 outward. These ducts vary in the degree and complication of 
 their development, according to the importance of the task assigned 
 to them. In the lower orders, they serve merely to convey the egg- 
 rapidly to the exterior, and to supply it more or less abundantly 
 with an albuminous secretion. In the higher classes and in the 
 human subject, they are adapted to the more important function of 
 retaining the egg during the period of gestation, and of providing 
 during the same time for the nourishment of the young embryo. 
 
458 MALE OKGANS OF GENERATION, 
 
 CHAPTER ly. 
 
 ON Xrf^ SPERMATIC FLUID, AND THE MALE ORGANS 
 OF GENERATION. 
 
 The mature egg is not by itself capable of being developed into 
 the embryo. If simply discharged from the ovary and carried 
 through the oviducts toward the exterior, it soon dies and is de- 
 composed, like any other portion of the body separated from its 
 natural connections. It is only when fecundated by the spermatic 
 fluid of the male, that it is stimulated to continued development, 
 and becomes capable of a more complete organization. 
 
 The product of the male generative organs consists of a colorless, 
 somewhat viscid, and albuminous fluid, containing an innumerable 
 quantity of minute filamentous bodies, termed spermatozoa. The 
 name spermatozoa has been given to these bodies, on account of 
 their exhibiting under the microscope a very active and continu- 
 ous movement, bearing some resemblance to that of certain animal- 
 cules. 
 
 The spermatozoa of the human subject (Fig. 167, a) are about 
 g^o of an inch in length, according to the measurements of Kol- 
 liker. Their anterior extremity presents a somewhat flattened, 
 triangular-shaped enlargement, termed the "head." The head con- 
 stitutes about one-tenth part the entire length of the spermato- 
 zoon. The remaining portion is a very slender filamentous pro- 
 longation, termed the "tail," which tapers gradually backward, 
 becoming so exceedingly delicate towards its extremity, that it is 
 difiicult to be seen except when in motion. There is no further 
 organization or internal structure to be detected in any part of the 
 spermatozoon ; and the whole appears to consist, so far as can be 
 seen by the microscope, of a completely homogeneous, tolerably 
 firm, albuminoid substance. The terms head and tail, therefore, 
 as justly remarked by Bergmann and Leuckart,' are not used, 
 
 ' Vergleichende Physiologic. Stuftgnrt, 1852. 
 
MALE ORGANS OF GENERATION. 
 
 459 
 
 when describing the different parts of the spermatozoon, in the 
 sanae sense as that in which they would be applied to the corre- 
 sponding parts of an animal, but simply for the sake of conveni- 
 ence; just as one might speak of the head of an arrow, or the tail 
 of a comet. 
 
 In the lower animals, the spermatozoa have usually the same 
 general form as in the human subject ; that is, they are slender 
 filamentous bodies, with the anterior extremity more or less en- 
 larged. In the rabbit they have a head which is roundish and 
 flattened in shape, somewhat resembling the globules of the blood. 
 In the rat (Fig. 167, b) they are much larger than in man, raeasur- 
 
 Fig. 167. 
 
 Spkrmatozoa. — a. Humao. b. Of Rat. c. Of Menobranchus. Magnified 4S0 times. 
 
 ing nearly y^? of an inch in length. The head is conical in shape, 
 about one-twentieth the whole length of the filament, and often 
 slightly curved at its anterior extremity. In the frog and in rep- 
 tiles generally, the spermatozoa are longer than in quadrupeds. 
 In the Menobranchus, or great American water-lizard, they are of 
 very unusual size (Fig.l(>7, c), measuring not less than ^\ of an 
 
460 MALE ORGANS OF GENERATION. 
 
 inch in length, about one-third of which is occupied by the head, 
 or enlarged portion of the filament. 
 
 The most remarkable peculiarity of the spermatozoa is their 
 very singular and active movement, to which we have already 
 alluded. If a drop of fresh seminal fluid be placed under the 
 microscope, the numberless minute filaments with which it is 
 crowded are seen to be in a state of incessant and agitated motion. 
 This movement of the spermatozoa, in many species of animals, 
 strongly resembles that of the tadpole; particularly when, as in 
 the human subject, the rabbit, &c., the spermatozoa consist of a 
 short and well defined head, followed by a long and slender tail. 
 Here the tail-like filament keeps up a constant lateral or vibratory 
 movement, by which the spermatozoon is driven from place to 
 place in the spermatic fluid, just as the fish or the tadpole is pro- 
 pelled through the water. In other instances, as for example in 
 the water-lizard, and in some parasitic animals, the spermatozoa 
 have a continuous writhing or spiral-like movement, which pre- 
 sents a very peculiar and elegant appearance when large numbers 
 of them are viewed together. 
 
 It is the existence of this movement which first suggested the 
 name of spermatozoa to designate the animated filaments of the 
 spermatic fluid ; and which has led some writers to attribute to 
 them an independent animal nature. This is, however, a very 
 erroneous mode of regarding them ; since they cannot properly be 
 considered as animals, notwithstanding the active character of their 
 movement, and the striking resemblance which it sometimes pre- 
 sents to a voluntary act. The spermatozoa are organic forms, 
 which are produced in- the testicles, and constitute a part of their 
 tissue ; just as the eggs, which are produced in the ovaries, natu- 
 rally form a part of the texture of these organs. Like the egg, 
 also, the spermatozoon is destined to be discharged from the organ 
 where it grew, and to retain, for a certain length of time afterward, 
 its vital properties. One of the most peculiar of these properties 
 is its power of keeping in constant motion ; which does not, how- 
 ever, mark it as a distinct animal, but only distinguishes it as a 
 peculiar structure belonging to the parent organism. The motion 
 of a spermatozoon is precisely analogous to that of a ciliated epi- 
 thelium cell. The movement of the latter will continue for some 
 hours after it has been separated from its mucous membrane, pro- 
 vided its texture be not injured, nor the process of decomposition 
 allowed to commence. In the same manner, the movement of the 
 
MALE ORGANS OF GENERATION. • 461 
 
 spermatozoa is a characteristic property belonging to them, which 
 continues for a certain time, even after they have been separated 
 from all connection with the rest of the body. 
 
 In order to preserve their vitality, the spermatozoa must be 
 kept at the ordinary temperature of the body, and preserved 
 from the contact of the air or other unnatural fluids. In this way, 
 they may be kept without difficulty many hours for purposes of 
 examination. But if the fluid in which they are kept be allowed 
 to dry, or if it be diluted by the addition of water, in tli'e case 
 of birds and quadrupeds, or if it be subjected to extremes of heat 
 or cold, the motion ceases, and the spermatozoa themselves soon 
 begin to disintegrate. 
 
 The spermatozoa are produced in certain glandular-looking 
 organs, the testicles^ w^hich are characteristic of the male, as the 
 ovaries are characteristic of the female. In man and all the higher 
 animals, the testicles are solid, ovoid-shaped bodies, composed 
 principally of numerous long, narrow, and convoluted tubes, the 
 "seminiferous tubes," somewhat similar in their general anatomical 
 characters to the tubuli uriniferi of the kidneys. These tubes lie 
 for the most part closely in contact with each other, so that nothing 
 intervenes between them except capillary bloodvessels and a little 
 areolar tissue. They commence, by blind, rounded extremities, near 
 the external surface of the testicle, and pursue an intricately con- 
 voluted course toward its central and posterior part. They are 
 not strongly adherent to each other, but may be readily unravelled 
 by manipulation, and separated from each other. 
 
 The formation of the spermatozoa, as it takes place in the 
 substance of the testicle, has been fully investigated by Kolliker. 
 According to his observations, as the age of puberty approaches, 
 beside the ordinary pavement epithelium lining the seminiferous 
 tubes, other cells or vesicles of larger size make their appearance 
 in these tubes, each containing from one to fifteen or twenty nuclei, 
 with nucleoli. It is in the interior of these vesicles that the 
 spermatozoa are formed ; their number corresponding usually with 
 that of the nuclei just mentioned. They are at first developed in 
 bundles of ten to twenty, held together by the thin membranous 
 substance which surrounds them, but are afterward set free by the 
 liquefaction of the vesicle, and then fill nearly the entire cavity of 
 the seminiferous ducts, mingled only with a YGvy minute quantity 
 of transparent fluid. 
 
 In the seminiferous tubes themselves, the spermatozoa are always 
 
462 MALE ORGANS OF GENERATION, 
 
 inclosed in the interior of their parent vesicles; they are liberated, 
 and mingled promiscuously together, only after entering the rete 
 testis and the head of the epididymis. 
 
 Beside the testicles, which are, as above stated, the primary and 
 essential parts of the male generative apparatus, there are certain 
 secondary or accessory organs, by means of which the spermatic 
 fluid is conveyed to the exterior, and mingled with certain secre- 
 tions .which assist in the accomplishment of its functions. 
 
 As the sperm leaves the testicle, it consists, as above mentioned, 
 almost entirely of the spermatozoa, crowded together in an opaque, 
 white, semi-fluid mass, which fills up the vasa eflferentia, and com- 
 pletely distends their cavities. It then enters the single duct 
 which forms the body and lower extremity of the epididymis, 
 following the long and tortuous course of this tube, until it 
 becomes continuous with the vas deferens; through which it is still 
 conveyed onward to the point where this canal opens into the 
 urethra. Throughout this course, it is mingled with a glairy, 
 mucus-like fluid, secreted by the walls of the epididymis and vas 
 deferens, in which the spermatozoa are enveloped. The mixture 
 is then deposited in the vesiculee seminales, where it accumulates 
 as fresh quantities are produced in the testicle and conveyed down- 
 ward by the spermatic duct. It is probable that a second secretion 
 is supplied also by the internal surface of the vesiculs seminales, 
 and that the sperm, while retained in their cavities, is not only 
 stored up for subsequent use, but is at the same time modified in 
 its properties by the admixture of another fluid. 
 
 At the time when the evacuation of the sperm takes place, it is 
 driven out from the seminal vesicles by the muscular contraction 
 of the surrounding parts, and meets in the urethra with the secre- 
 tions of the prostate gland, the glands of Cowper, and the mucous 
 follicles opening into the urethral passage. All these organs are at 
 that time excited to an unusual activity of secretion, and pour out 
 their different fluids in great abundance. 
 
 The sperm, therefore, as it is discharged from the urethra, is an 
 exceedingly mixed fluid, consisting of the spermatozoa derived 
 from the testicles, together with the secretions of the epididymis 
 and vas deferens, the prostate, Cowper's glands, and the mucous 
 follicles of the urethra. Of all these ingredients, it is the sperma- 
 tozoa which constitute the essential part of the seminal fluid. They 
 are the true fecundating element of the sperm, while all the others 
 are secondary in importance and perform only accessory functions. 
 
 Spallanzani found that if frog's semen be passed through a sue- 
 
MALE OEGANS OF GENERATION. 463 
 
 cession of filters, so as to separate the spermatozoa from the liquid 
 portions, the filtered fluid is destitute of any fecundating properties; 
 while the spermatozoa remaining entangled in the filter, if mixed 
 with a sufficient quantity of fluid of the requisite density for dilu- 
 tion, may still be successfully used for the impregnation of eggs. 
 It is well known, also, that animals or men from whom both 
 testicles have been removed, are incapable of impregnating the 
 female or her eggs ; while a removal or imperfection of any of the 
 other generative organs does not necessarily prevent the accom- 
 plishment of the function. 
 
 In most of the lower orders of animals there is a periodical 
 development of the testicles in the male, corresponding in time with 
 that of the ovaries in the female. As the ovaries enlargje and the 
 eggs ripen in the one sex, so in the other the testicles increase in 
 size, as the season of reproduction approaches, and become turgid 
 with spermatozoa. The accessory organs of generation, at the 
 same time, share the unusual activity of the testicles, and become 
 increased in vascularity and ready to perform their part in the 
 reproductive function. 
 
 In the fish, for example, where the testicles occupy a similar posi- 
 tion in the abdomen as the ovaries in the opposite sex, these bodies 
 enlarge, become distended with their contents, and project into the 
 peritoneal cavity. Each of the two sexes is then at the same time 
 under the influence of a corresponding excitement. The unusual 
 development of the generative organs reacts upon the entire system, 
 and produces a state of peculiar activity and excitability, known as 
 the condition of "erythism." The female, distended with eggs, feels 
 the impulse which leads to their expulsion ; while the male, bear- 
 ing the weight of the enlarged testicles and the accumulation of 
 newly-developed spermatozoa, is impelled by a similar sensation to 
 the discharge of the spermatic fluid. The two sexes, accordingly, 
 are led by instinct at this season to frequent the same situations. 
 The female deposits her eggs in some spot favorable to the protec- 
 tion and development of the young ; after which the male, appa- 
 rently attracted and stimulated by the sight of the new-laid eggs, 
 discharges the spermatic fluid upon them, and their impregnation 
 is accomplished. 
 
 In such instances as the above, where the male and female gene- 
 rative products are discharged separately by the two sexes, the 
 subsequent contact of the eggs with the spermatic fluid would seem 
 to depend altogether on the occurrence of fortuitous circumstances, 
 and their impregnation, therefore, be often liable to fail. In point 
 
464 * MALE ORGANS OF GENERATION. 
 
 of fact, however, the simultaneous functional excitement of the 
 two sexes and the operation of corresponding instincts, leading 
 them to ascend the same rivers and to frequent the same spots, 
 provide with sufficient certainty for the impregnation of the eggs. 
 In these animals, also, the number of eggs produced by the female 
 is very large, the ovaries being often so distended as to fill nearly 
 the whole of the abdominal cavity; so that, although many of the 
 eggs may be accidentally lost, a sufficient number will still be im- 
 pregnateid and developed to provide for the continuation of the 
 species. 
 
 In other instances, an actual contact takes place between the 
 sexes at the time of reproduction. In the frog, for example, the 
 male fastens himself upon the back of the female by the anterior 
 extremities, which seem to retain their hold by a kind of spasmodic 
 contraction. This continues for one or two days, during which 
 time the mature eggs, which have been discharged from the ovary, 
 are passing downward through the oviducts. At last they are ex- 
 pelled from the anus, while at the same time the seminal fluid of 
 the male is discharged upon them, and impregnation takes place. 
 
 In the higher classes of animals, however, and in man, where the 
 egg is to be retained in the body of the female parent during its 
 development, the spermatic fluid is introduced into the female 
 generative passages by sexual congi-ess, and meets the egg at or 
 soon after its discharge from the ovary. The same correspondence, 
 however, between the periods of sexual excitement in the male and 
 female, is visible in many of these animals, as well as in fish and 
 reptiles. This is the case in most species which produce young but 
 once a year, and at a fixed period, as the deer and the wild hog. In 
 other species, on the contrary, such as the dog, as well as the rabbit, 
 the guinea pig, &c., where several broods of young are produced 
 during the year, or where, as in the human subject, the generative 
 epochs of the female recur at short intervals, so that the particular 
 period of impregnation is comparatively indefinite, the generative 
 apparatus of the male is almost constantly in a state of full deve- 
 lopment ; and is excited to action at particular periods, apparently 
 by some influence derived from the condition of the female. 
 
 In the quadrupeds, accordingly, and in the human species, the 
 contact of the sperm with the egg aud the fecundation of the latter 
 take place in the generative passages of the female ; either in the 
 uterus, the Fallopian tubes, or even upon the surface of the ovary ; 
 in each of which situations the spermatozoa have been found, after 
 the accomplishment of sexual intercourse. 
 
PERIODICAL OVULATION. 465 
 
 CHAPTER V. 
 
 ON PERIODICAL OVULATION, AND THE FUNCTION 
 OF MENSTRUATION. 
 
 L PERIODICAL OVULATION. 
 
 We have already spoken in general terms of the periodical ripen- 
 ing of the eggs and their discharge from the generative organs of 
 the female. This function is known by the name of " ovulation," 
 and may be considered as the primary and most important act in 
 the process of reproduction. We shall therefore enter more fully 
 into the consideration of certain particulars in regard to it, by 
 which its nature and conditions may be more clearly understood. 
 
 1st, Eggs exist originally in the ovaries of all animals^ as part of 
 their natural structure. In describing the ovaries of iish and reptiles 
 we have said that they consist of nothing more than Graafian vesi- 
 cles, each vesicle containing an egg^ and united with each other by 
 loose areolar tissue and a peritoneal investment. In the higher 
 animals and in the human subject, the essential constitution of the 
 ovary is the same ; only its fibrous tissue is more abundant, so that 
 the texture of the entire organ is more dense, and its figure more 
 compact. In all classes, however, without exception, the interior 
 of each Graafian vesicle is occupied by an Qgg ; and it is from this 
 egg that the young ofispring is afterward to be produced. 
 
 The process of reproduction was formerly regarded as essentially 
 different in the oviparous and viviparous animals. In the ovipa- 
 rous classes, such as most fish, and all reptiles and birds, the young 
 animal was well known to be formed from an egg produced by the 
 female; while in the viviparous animals, or those which brino- 
 forth their young alive, such as the quadrupeds and the human 
 species, the embryo was supposed to originate in the body of the 
 female, by some altogether peculiar and mysterious process, in 
 consequence of sexual intercourse. As soon, however, as the 
 microscope began to be used in the examination of the tissues, 
 30 
 
466 OVULATION AND FUNCTION OF MENSTRUATION. 
 
 the ovaries of quadrupeds were also found to contain eggs. These 
 eggs had previously escaped observation on account of their simple 
 structure and minute size ; but they were nevertheless found to 
 possess all the most essential characters belonging to the larger 
 eggs of the oviparous animals. 
 
 The true difference in the process of reproduction, between the 
 two classes, is therefore merely an apparent, not a fundamental one. 
 In fish, reptiles, and birds, the egg is discharged by the female 
 before or immediately after impregnation, and the embryo subse- 
 quently developed and hatched externally. In the quadrupeds and 
 the human species, on the other hand, the egg is retained within 
 the body of the female until the embryo is developed ; when the 
 membranes are ruptured and the young expelled at the same time. 
 In all classes, however, viviparous as well as oviparous, the young 
 is produced equally from an egg; and in all classes the egg, 
 sometimes larger and sometimes smaller, but always consisting 
 essentially of a vitellus and a vitelline membrane, is contained 
 originally in the interior of an ovarian follicle. 
 
 The egg is accordingl}'-, as we have already intimated, an integral 
 part of the ovarian tissue. It may be found there long before the 
 generative function is established, and during the earliest periods 
 of life. It may be found without difficulty in the newly bora 
 female infant, and may even be detected in the foetus before birth. 
 Its growth and nutrition, also, are provided for in the same man- 
 ner with that of other portions of the bodily structure. 
 
 2d. 27iese eggs become more fully developed at a certain age, ichen 
 the generative function is about to be established. During the early 
 periods of life, the ovaries and their contents, like many other 
 organs, are imperfectly developed. They exist, but they are as 
 yet inactive, and incapable of performing any function. In the 
 yo^ng chick, for example, the ovary is of small size ; and the eggs, 
 instead of presenting the voluminous, yellow, opaque vitellus which 
 they afterward exhibit, are minute, transparent, and colorless. In 
 the young quadrupeds, and in the human female during infancy 
 and childhood, the ovaries are equally inactive. They are small, 
 friable, and of a nearly homogeneous appearance to the naked eye ; 
 presenting none of the enlarged follicles, filled with transparent 
 fluid, which are afterward so readily distinguished. At this time, 
 accordingly, the female is incapable of bearing young, because the 
 ovaries are inactive, and the eggs which they contain immature. 
 
 At a certain period, however, which varies in the time of its 
 
PERIODICAL OVULATION. 467 
 
 occurrence for different species of animals, the sexual apparatus 
 begins to enter upon a state of activity. The ovaries increase in 
 size, and their circulation becomes more active. The eggs, also, 
 instead of remaining quiescent, take on a rapid growth, and the 
 structure of the vitellus is completed by the abundant deposit of 
 oleaginous granules in its interior. Arrived at this state, the eggs 
 are ready for impregnation, and the female becomes capable of 
 bearing young. She is then said to have arrived at tl^ state of 
 " puberty," or that condition in which the generative organs are 
 fully developed. This condition is accompanied by a visible 
 alteration in the system at large, which indicates the complete 
 development of the entire organism. In many birds, for example, 
 the plumage assumes at this period more varied and brilliant 
 colors; and in the common fowl the comb, or "crest," enlarges 
 and becomes red and vascular. In the American deer (Cervus 
 virginianus), the coat, which during the first year is mottled with 
 white, becomes in the second year, of a uniform tawny or reddish 
 tinge. In nearly all species, the limbs become more compact and 
 the body more rounded ; and the whole external appearance is so 
 altered, as to indicate that the animal has arrived at the period of 
 puberty, and is capable of reproduction. 
 
 3d. Successive crops of eggs^ in the adult female, ripen and are 
 discharged independently of sexual intercourse. It was formerly sup- 
 posed, as we have mentioned above, that in the viviparous animals 
 the germ was formed in the body of the female only as a conse- 
 quence of sexual intercourse. Even after the important fact 
 became known that eggs exist originally in the ovaries of these 
 animals, and are only fecundated by the influence of the sperm- 
 atic fluid, the opinion still prevailed that the occurrence of sexual 
 intercourse was the cause of their being discharged from the ovary, 
 and that the rupture of a Graafian vesicle in this organ was a 
 certain indication that coitus had taken place. 
 
 This opinion, however, was altogether unfounded. We already 
 know that in fish and reptiles the mature eggs not only leave the 
 ovary, but are actually discharged from the body of the female 
 while still unimpregnated, and only subsequently come in contact 
 with the spermatic fluid. In fowls, also, it is a matter of common 
 observation that the hen will continue to lay fully-formed eggs, if 
 well supplied with nourishment, without the presence of the cock ; 
 only these eggs, being unimpregnated, are incapable of producing 
 
468 OVULATION AND FUNCTION OF MENSTRUATION. 
 
 chicks. In oviparous animals, therefore, the discharge of the egg, 
 as well as its formation, is independent of sexual intercourse. 
 
 Continued observation shows this to be the case, also, in the 
 viviparous quadrupeds. The researches of Bischoff, Pouchet, and 
 Coste have demonstrated that in the sheep, the pig, the bitch, the 
 rabbit, &c., if the female be carefully kept from the male until after 
 the period of puberty is established, and then killed, examination 
 of the q«iries will show that Graafian vesicles have matured, rup- 
 tured, and discharged their eggs, in the same manner as though 
 sexual intercourse had taken place. Sometimes the vesicles are 
 found distended and prominent upon the surface of the ovary ; 
 sometimes recently ruptured and collapsed; and sometimes in vari- 
 ous stages of cicatrization and atrophy, Bischoff',' in several in- 
 stnnces of this kind, actually found the unimpregnated eggs in the 
 oviduct, on their way to the cavity of the uterus. In those animals 
 in which the ripening of the eggs takes place at short intervals, as, 
 for example, the sheep, the pig, and the cow, it is very rare to exa- 
 mine the ovaries in any instance where traces of a more or less 
 recent rupture of the Graafian follicles are not distinctly visible. 
 
 One of the most important facts, derived from the examination 
 of such cases as the above, is that the ovarian eggs become deve- 
 loped and are discharged in successive crops, which follow each 
 other regularly at periodical intervals. If we examine the ovary 
 of the fowl, for example (Fig. 163), we see at a glance how the eggs 
 grow and ripen, one after tlie other, like fruit upon a vine. In this 
 instance, the process of evolution is very rapid ; and it is easy to 
 distinguish, at the same time, eggs which are almost microscopic in 
 size, colorless, and transparent; those which are larger, firmer, 
 somewhat opaline, and yellowish in hue ; and finally those which 
 are fully developed, opaque, of a deep orange color, and just ready 
 to leave the ovary. 
 
 It will be observed that in this instance the difference between 
 the undeveloped and mature eggs consists principally in the size of 
 the vitellus, which is furthermore, for reasons previously given 
 (Chap. III.), very much larger than in the quadrupeds. It is also 
 seen that it is the increased size of the vitellus alone, by which the 
 ovarian follicle is distended and ruptured, and the egg finally dis- 
 charged. 
 
 In the human species and the quadrupeds, on the other hand, 
 
 ' Memoire sur la cliute perioflique de I'oeuf, &c., Annales fles Sciences Naturelles, 
 Aoiit — Septembre, 1844. 
 
PERIODICAL OVULATION". 469 
 
 the microscopic egg never becomes large enough to distend the 
 follicle by its own size. The rupture of the follicle and the libera- 
 tion of the egg are accordingly provided for, in these instances, by 
 a totally different mechanism. 
 
 In the earlier periods of life, in man and the higher animals, the 
 egg is contained in a Graafian follicle which closely embraces its 
 exterior, and is consequently hardly larger than the egg itself. As 
 puberty approaches, those follicles which are situated near the free 
 surface of the ovary become enlarged by the accumulation of a 
 colorless serous fluid in their cavity. We then find that the ovary, 
 when cut open, shows a considerable number of globular, transpa- 
 rent vesicles, readily perceptible by the eye, the smaller of which 
 are deep seated, but which increase in size as they approach the 
 free surface of the organ. These vesicles are the Graafian follicles, 
 which, in consequence of the advancing maturity of the eggs con- 
 tained in them, gradually enlarge as the period of generation ap- 
 proaches. 
 
 The Graafian follicle at this time consists of a closed globular 
 sac or vesicle, the external wall of which, though quite translucent, 
 has a fibrous texture under the microscope and is well supplied 
 with bloodvessels. This fibrous and vascular wall is distinguished 
 by the name of the " membrane of the vesicle." It is not very 
 firm in texture, and if roughly handled is easily ruptured. 
 
 The membrane of the vesicle is lined throughout by a thin layer 
 of minute granular cells, which form for it a kind of epithelium, 
 similar to the epithelium of the pleura, pericardium, and other 
 serous membranes. This layer is termed the membrana granulosa. 
 It adheres but slightly to the membrane of the vesicle, and may 
 easily be detached by careless manipulation before the vesicle is 
 opened, being then mingled, in the form of light flakes and shreds, 
 with the serous fluid contained in the vesicle. 
 
 At the most superficial part of the Graafian follicle, or that 
 which is nearest the surface of the ovary, the membrana granulosa 
 is thicker than elsewhere. Its cells are here accumulated, in a 
 kind of mound or "heap," which has received the name of the 
 cumulus proligervs. It is sometimes called the discus proligerus^ 
 because the thickened mass, when viewed from above, has a some- 
 what circular or disk-like form. In the centre of this thickened 
 portion of the membrana granulosa the egg is imbedded. It is 
 accordingly always situated at the most superficial portion of the 
 follicle, and advances in this way toward the surface of the ovary. 
 
470 OVULATION AND FUNCTION OF MENSTRUATION. 
 
 As the period approaches at which the egg is destined to be dis- 
 charged, the Graafian follicle becomes more vascular, and enlarges 
 by an increased exudation of serum into its cavity. It then begins 
 
 Fig. 168. 
 
 Graafian Follicle, near the period of rupture. — a. Membrane of the vesicle. 6. Membrana 
 granulosa, c. Cavity of follicle, d. Egg. e. Peritoneum. /. Tunica albuginea. g, g. Tissue of 
 llie ovary. 
 
 to project from the surface of the ovary, still covered by the albu- 
 gineous tunic and the peritoneum, (Fig. 168.) The constant accu- 
 mulation of fluid, however, in the follicle, exerts such a steady and 
 increasing pressure from within outward, that the albugineous tunic 
 and the peritoneum successively yield before it; until the Graafian 
 follicle protrudes from the ovary as a tense, rounded, translucent 
 vesicle, in which the sense of fluctuation can be readily perceived 
 on applying the fingers to its surface. Finally, the process of effu- 
 sion and distension still going on, the wall of the vesicle yields at 
 its most prominent portion, the contained fluid is driven out with a 
 o'ush, by the reaction and elasticity of the neighboring ovarian 
 
 tissues, carrying with it the egg^ 
 still entangled in the cells of the 
 proligerous disc. 
 
 The rupture of the Graafian 
 vesicle is accompanied, in some 
 instances, by an abundant hemor- 
 rhage, which takes place from the 
 internal surface of the congested 
 follicle, and by which its cavity 
 is filled with blood. This occurs 
 in the human subject and in the 
 pig, and to a certain extent, also, 
 in other of the lower animals. 
 Sometimes, as in the cow, where 
 
 Fig. 169, 
 
 Ovary with Graafian Follicle 
 kdptured; at a, egg just discluirged with a 
 portion of membraua granulosa. 
 
PERIODICAL OVULATION. 471 
 
 iio hemorrhage takes place, the Graafian vesicle when ruptured 
 simply collapses; after which, a slight exudation, more or less tinged 
 with blood, is poured out during the course of a few hours. 
 
 Notwithstanding, however, these slight variations, the expulsion 
 of the egg takes place, in the higher animals, always in the manner 
 above described, viz., bj the accumulation of serous fluid in the 
 cavity of the Graafian follicle, by which its walls are gradually dis- 
 tended and finally ruptured. 
 
 This process takes place in one or more Graafian follicles at a 
 time, according to the number of young which the animal produces 
 at a birth. In the bitch and the sow, where each litter consists of 
 from six to twenty young ones, a similar number of eggs ripen and 
 are discharged at each period. In the mare, the cow, and in the 
 iiuman female, where there is usually but one foetus brought forth 
 at a birth, the eggs are matured singly, and the Graafian vesicles 
 luptured, one after another, at successive periods of ovulation. 
 
 4th. The ripening and discharge of the egg are accompanied by a pecu- 
 liar condition of the entire system^ known as the " rutting'''' condition^ or 
 '■'' (xstruationr The peculiar congestion and functional activity of 
 the ovaries at each period of ovulation, act by sympathy upon the 
 other generative organs, and produce in them a greater or less de- 
 gree of excitement, according to the particular species of animal. 
 Almost always there is a certain amount of congestion of the entire 
 generative apparatus ; Fallopian tubes, uterus, vagina, and external 
 organs. The secretions of the vagina and neighboring parts are 
 more particularly affected, being usually increased in quantity and 
 at the same time altered in quality. In the bitch, the vaginal raur 
 cous membrane becomes red and tumefied, and pours out an abun- 
 dant secretion which is often more or less tinged with blood. The 
 secretions acquire also at this time a peculiar odor, which ap- 
 ]iears to attract the male, and to excite in him the sexual impulse. 
 An unusual tumefaction and redness of the vagina and vulva are 
 also very perceptible in the rabbit ; and in some species of apes it 
 has been observed that these periods are accompanied not only by 
 a bloody discharge from the vulva, but also by an engorgement and 
 infiltration of the neighboring parts, extending even to the skin of 
 the buttocks, the thighs, and the under part of the tail.^ 
 
 The system at large is also visibly affected by the process going 
 on in the ovary. In the cow, for example, the approach of an 
 
 ' Pouchet, Tlieorie positive de I'ovulation, &c. Paris, 1847, p. 230. 
 
472 OVULATION AND FUNCTION OF MENSTRUATION. 
 
 oestrual period is marked by an unusual restlessness and agitation, 
 easily recognized by an ordinary observer. The animal partially 
 loses her appetite. She frequently stops browsing, looks about un- 
 easily, perhaps runs from one side of the field to the other, and then 
 recommences feeding, to be disturbed again in a similar manner 
 after a short interval. Her motions are rapid and nervous, and her 
 hide often rough and disordered ; and the whole aspect of the ani- 
 mal indicates the presence of some unusual excitement. After this 
 condition is fully established, the vaginal secretions show them- 
 selves in unusual abundance, and so continue for one or two days; 
 after which the symptoms, both local and general, subside sponta- 
 neously, and the animal returns to her usual condition. 
 
 It is a remarkable fact, in this connection, that the female of 
 these animals will allow the approaches of the male only during and 
 immediately after the oestrual period ; that is, just when the egg is 
 recently discharged and ready for impregnation. At other times, 
 when sexual intercourse would be necessarily fruitless, the instinct 
 of the animal leads her to avoid it ; and the concourse of the sexes 
 is accordingly made to correspond in time with the maturity of the 
 egg and its aptitude for fecundation. 
 
 II, MENSTRUATION. 
 
 In the human female, the return of the periods of ovulation is 
 marked by a peculiar group of phenomena which are known as 
 menstruation, and which are of sufficient importance to be described 
 by themselves. 
 
 During infancy and childhood the sexual system, as we have 
 mentioned above, is inactive. No discharge of eggs takes place 
 from the ovaries, and no external phenomena show themselves, 
 connected with the reproductive function. 
 
 At the age of fourteen or fifteen years, however, a change begins 
 to manifest itself. The limbs become rounder, the breasts increase 
 in size, and the entire aspect undergoes a peculiar alteration, which 
 indicates the approaching condition of maturity. At the same 
 time a discharge of blood takes place from the generative passages, 
 accompanied by some disturbance of the general system, and the 
 female is then known to have arrived at the period of puberty. 
 
 Afterward, the bloody discharge just spoken of returns at regular 
 
MENSTRUATION. 473 
 
 intervals of four weeks; and, on account of this recurrence corres- 
 ponding with the passage of successive lunar months, its phenomena 
 are designated by the name of the "menses" or the "menstrual 
 periods." The menses return with regularity, from the time of 
 their first appearance, until the age of about forty-five years. 
 During this period, the female is capable of bearing children, and 
 sexual intercourse is liable to be followed by pregnancy. After 
 the forty-fifth year, the periods first become irregular, and then 
 cease altogether; and their final disappearance is an indication that 
 the woman is no longer fertile, and that pregnancy cannot again 
 take place. 
 
 Even during the period above referred to, from the age of fifteen 
 to forty-five, the regularity and completeness of the menstrual 
 periods indicate to a great extent the aptitude of individual females 
 for impregnation. It is well known that all those causes of ill 
 health which derange menstruation are apt at the same time to 
 interfere with pregnancy ; so that women whose menses are habi- 
 tually regular and natural are much more likely to become preg- 
 nant, after sexual intercourse, than those in whom the periods are 
 absent or irregular. 
 
 If pregnancy happen to take place, however, at any time during 
 the child-bearing period, the menses are suspended during the con- 
 tinuance of gestation, and usually remain absent after delivery, as 
 long as the woman continues to nurse her child. They then re- 
 commence, and subsequently continue to appear as before. 
 
 The menstrual discharge consists of an abundant secretion of 
 mucus mingled with blood. When the expected period is about 
 to come on, the female is affected with a certain degree of discomfort 
 and lassitude, a sense of weight in the pelvis, and more or less dis- 
 inclination to society. These symptoms are in some instances 
 slightly pronounced, in others more troublesome. An unusual 
 discharge of vaginal mucus then begins to take place, which soon 
 becomes yellowish or rusty brown in color, from the admixture of 
 a certain proportion of blood; and by the second or third day the 
 discharge has the appearance of nearly pure blood. The unpleasant 
 sensations which were at first manifest then usually subside ; and 
 the discharge, after continuing for a certain period, begins to grow 
 more scanty. Its color changes from a pure red to a brownish or 
 rusty tinge, until it finally disappears altogether, and the female 
 returns to her ordinary condition. 
 
 The menstrual epochs of the human female correspond with the 
 
474 OVULATION AND FUNCTION OF MENSTEUATION. 
 
 periods of oestruation in the lower animals. Their general resem- 
 blance to these periods is too evident to require demonstration. 
 Like them, they are absent in the immature female ; and begin 
 to take place only at the period of puberty, when the aptitude 
 for impregnation first commences. Like them, they recur during 
 the child-bearing period at regular intervals ; and are liable to the 
 same interruption bj' pregnancy and lactation. Finally, their dis- 
 appearance corresponds with the cessation of fertility. 
 
 The periods of oestruation, furthermore, in many of the lower 
 animals, are accompanied, as we have already seen, with an unusual 
 discharge from the generative passages; and this discharge is fre- 
 quently more or less tinged with blood. In the human female the 
 bloody discharge is more abundant than in other instances, but it is 
 evidently a phenomenon differing only in degree from that which 
 shows itself in many species of animals. 
 
 The most complete evidence, however, that the period of men- 
 struation is in realitv that of ovulation, is derived from the results 
 of direct observation. A sufficient number of instances have now 
 been observed to show that at the menstrual epoch a Graafian 
 vesicle becomes enlarged, ruptures, and discharges its egg. Cruik- 
 shank* noticed such a case so long ago as 1797. Negrier^ relates 
 two instances, communicated to him by Dr. Ollivier d' Angers, in 
 which, after sudden death during menstruation, a bloody and rup- 
 tured Graafian vesicle was found in the ovary. Bischoff^ speaks of 
 four similar cases in his own observation, in three of which the 
 vesicle was just raptured, and in the fourth distended, prominent, 
 and ready to burst. Coste^ has met with several of the same kind. 
 Dr. Michel* found a vesicle ruptured and filled with blood in a 
 woman who was executed for murder while the menses were pre- 
 sent. We have also^ met with the same appearances in a case of 
 death from acute disease, on the second day of menstruation. 
 
 The process of ovulation, accordingly, in the human female, 
 accompanies and forms a part of that of menstruation. As the 
 menstrual period comes on, a congestion takes place in nearly the 
 
 ' London Philosophical Transactions, 1797, p. 135. 
 
 ^ Recherches sur les Ovaires, Paris, 1840, p. 78. 
 
 '* Annales des Sciences Naturelles, August, 1844. 
 
 '' Histoire du Developpement des Corps Organises, Paris, 1847, vol i. p. 221. 
 
 5 Am. .Tourn. Med. Sci., July, 1848. 
 
 ^ Corpus Luteum of Menstruation and Pregnancy, in Transactions of American 
 Medical Association, Philadelphia, 1851. 
 
MENSTRUATION. 475 
 
 whole of the generative apparatus; in the Fallopian tubes and the 
 uterus, as well as in the ovaries and their contents. One of the 
 Graafian follicles is more especially the seat of an unusual vascular 
 excitement. It becomes distended by the fluid which accumulates 
 in its cavity, projects from the surface of the ovary, and is finally 
 ruptured, in the same manner as we have already described this 
 process taking place in the lower animals. 
 
 It is not quite certain at what particular period of the menstrual 
 flow the rupture of the vesicle and discharge of the egg take place. 
 It is the opinion of Bischoflf, Pouchet, and Kaciborski, that the 
 regular time for this rupture and discharge is not at the commence- 
 ment, but towards the termination of the period. Coste' has ascer- 
 tained, from his observations, that the vesicle ruptures sometimes 
 in the early part of the menstrual epoch, and sometimes later. So 
 far as we can learn, therefore, the precise period of the discharge 
 of the egg is not invariable. Like the menses themselves, it may 
 take place apparently a little earlier or a little later, according to 
 various accidental circumstances; but it always occurs at some 
 time in connection with the menstrual flow, and constitutes the 
 most essential and important part of the catamenial process. 
 
 The egg, when discharged from the ovary, enters the fimbriated 
 extremity of the Fallopian tube, and commences its passage toward 
 the uterus. The mechanism by which it finds its way into and through 
 the Fallopian tube is different, in the quadrupeds and the human 
 species, and in birds and reptiles. In the latter, the bulk of the egg 
 or mass of eggs discharged is so great as to fill entirely the wide 
 extremity of the oviduct, and they are afterward conveyed down- 
 ward by the peristaltic action of the muscular coat of this canal. 
 In the higher classes, on the contrary, the egg is microscopic in 
 size, and would be liable to be lost, were there not some further 
 provision for its safety. The wide extremity of the Fallopian tube, 
 accordingly, which is here directed toward the ovary, is lined with 
 ciliated epithelium ; and the movement of the cilia, which is 
 directed from the ovary toward the uterus, produces a kind of con- 
 verging stream, or vortex, by which the egg is necessarily drawn 
 toward the narrow portion of the tube, and subsequently conducted 
 to the cavity of the uterus. 
 
 Accidental causes, however, sometimes disturb this regular course 
 or passage of the egg. The egg may be arrested, for example, 
 
 ' Loc cit. 
 
476 OVULATION AND FUNCTION OF MENSTRUATION. 
 
 at the surfiice of the ovary, and so fail to enter the tube at all. 
 If fecundated in this situation, it will then give rise to "ovarian 
 pregnancy." It may escape from the fimbriated extremity into the 
 peritoneal cavity, and form attachments to some one of the neigh- 
 boring organs, causing "abdominal pregnancy;" or finally, it may 
 stop at any part of the Fallopian tube, and so give origin to "tubal 
 pregnancy." 
 
 The egg, immediately upon its discharge from the ovary, is ready 
 for impregnation. If sexual intercourse happen to take place about 
 that time, the egg and the spermatic fluid meet in some part of the 
 female generative passages, and fecundation is accomplished. It 
 appears, from various observations of Bischoff, Coste, and others, 
 that this contact may take place between the egg and the sperm, 
 either in the uterus or any part of the Fallopian tubes, or even 
 upon the surface of the ovary. If, on the other hand, coitus do not 
 take place, the egg passes down to the uterus unimpregnated, loses 
 its vitality after a short time, and is finally carried away with the 
 uterine secretions. 
 
 It is easily understood, therefore, why sexual intercourse should 
 be more liable to be followed by pregnancy when it occurs about 
 the menstrual epoch than at other times. This fact, which was long 
 since established as a matter of observation by practical obstetri- 
 cians, depends simply upon the coincidence in time between men- 
 struation and the discharge of the egg. Before its discharge, the 
 egg is immature, and unprepared for impregnation ; and after the 
 menstrual period has passed, it gradually loses its freshness and 
 vitality. The exact length of time, however, preceding and follow- 
 ing the menses, during which impregnation is still possible, has not 
 been ascertained. The spermatic fluid, on the one hand, retains its 
 vitality for an unknown period after coition, and the egg for an 
 unknown period after its discharge. Both these occurrences may, 
 therefore, either precede or follow each other within certain limits, 
 and impregnation be still possible ; but the precise extent of these 
 limits is still uncertain, and is probably more or less variable in 
 diffent individuals. 
 
 The above facts indicate also the true explanation of certain 
 exceptional cases, which have sometimes been observed, in which 
 fertility exists without menstruation. Various authors (Churchill, 
 Reid, Velpeau, &c.) have related instances of fruitful women in whom 
 the menses were very scanty and irregular, or even entirely absent. 
 The menstrual flow is, in fact, only the external sign and accompa- 
 
MENSTRUATION". 477 
 
 niment of a more important process taking place within. It is 
 habitual]}'' scanty in some individuals, and abundant in others. 
 Such variations depend upon the condition of vascular activity of 
 the system at large, or of the uterine organs in particular; and 
 though the bloody discharge is usually an index of the general 
 aptitude of these organs for successful impregnation, it is not an 
 absolute or necessary requisite. Provided a mature egg be dis- 
 charged from the ovary at the appointed period, menstruation pro- 
 perly speaking exists, and pregnancy is possible. 
 
 The blood which escapes during the menstrual flow is supplied 
 by the uterine mucous membrane. If the cavity of the uterus be 
 examined after death during menstruation, its internal surface is 
 seen to be smeared with a thickish bloody fluid, which may be 
 traced through the uterine cervix and into the vagina. The Fallo- 
 pian tubes themselves are sometimes found excessively congested, 
 and filled with a similar bloody discharge. The menstrual blood 
 has also been seen to exude from the uterine orifice in cases of pro- 
 cidentia uteri, as well as in the natural condition by examination 
 ■with the vaginal speculum. It is discharged by a kind of capillary 
 hemorrhage, similar to that which takes place from the lungs in 
 cases of hemoptysis, only less sudden and violent. The blood does 
 not form any visible coagulum, owing to its being gradually exuded 
 from many minute points, and mingled with a large quantity of 
 mucus. When poured out, however, more rapidly or in larger 
 quantity than usual, as in cases of menorrhagia, the menstrual blood 
 coagulates in the same manner as if derived from any other source. 
 The hemorrhage which supplies it comes from the whole extent of 
 the mucous membrane of the body of the uterus, and is, at the same 
 time, the consequence and the natural termination of the periodical 
 congestion of the parts. 
 
478 MENSTRUATION AND PREGNANCY. 
 
 CHAPTER VI. 
 
 ON THE CORPUS LUTEUM OF MENSTRUATION AND 
 
 PREGNANCY. 
 
 After the rupture of the Graafian vesicle at the menstrual 
 period, a bloody cavity is left in the ovary which is subsequently 
 obliterated by a kind of granulating process, somewhat similar in 
 character to the healing of an abscess. For the Graafian vesicle 
 is intended simply for the formation and growth of the egg. 
 After the egg therefore has arrived at maturity and has been dis- 
 charged, the Graafian follicle has no longer any function to per- 
 form. It then only remains for it to pass through a process of 
 obliteration and atrophy, as an organ which has become useless 
 and obsolete. While undergoing this process, the Graafian vesicle 
 is at one time converted into a peculiar, solid, globular body, which 
 is called the corpus luteum ; a name given to it on account of the 
 yellow color which it acquires at a certain period of its formation. 
 
 We shall proceed to describe the corpus luteum in the human 
 species; first, as it follows the ordinary course of development 
 after menstruation ; and secondly, as it is modified in its growth 
 and appearance during the existence of pregnancy. 
 
 I. CORPUS luteum of menstruation. 
 
 We have already described, in the preceding chapter, the man- 
 ner in which a Graafian vesicle, at each menstrual epoch, swells, 
 protrudes from the surface of the ovary, and at last ruptures and 
 discharges its egg. At the moment of rupture, or immediately 
 after it, an abundant hemorrhage takes place in the human sub- 
 ject from the vessels of the follicle, by which its cavity is filled 
 with blood. This blood coagulates soon after its exudation, as 
 it would do if extravasated in any other part of the body, and 
 the coagulum is retained in the interior of the Graafian follicle. 
 
CORPUS LUTEUM OF MENSTRUATION. 
 
 479 
 
 & - h 
 
 Graafian Follicle 
 receully ruplured during 
 nienstniation, and filled 
 with a bloody coaguliim ; 
 shown in longitudinal sec- 
 tion. — a. Tissue of the 
 ovary, b. Membrane of the 
 vesicle, c. Point of rupture. 
 
 The opening by which the Qgg makes its escape is usually not an 
 extensive laceration, but a minute rounded perforation, often not 
 more than half a line in diameter. A small probe, introduced 
 through this opening, passes directly into the 
 cavity of the follicle. If the Graafian follicle 
 be opened at this time by a longitudinal inci- 
 sion (Fig. 170), it will be seen to form a globu- 
 lar cavity, one-half to three-quarters of an 
 inch in diameter, containing a soft, recent, 
 dark colored coagulum. This coagulum has 
 no organic connection with the walls of the 
 follicle, but lies loose in its cavity and may be 
 easily turned out with the handle of a knife. 
 There is sometimes a slight mechanical adhe- 
 sion of the clot to the eds^es of the lacerated 
 opening, just as the coagulum in a recently 
 ligatured artery is entangled by the divided 
 edges of the internal and middle coats; but 
 there is no continuity of substance between 
 them, and the clot may be everywhere readily 
 separated by careful manipulation. The membrane of the vesicle 
 presents at this time a smooth, transparent, and vascular internal 
 surface, without any alteration of color, consistency, or texture. 
 
 An important change, however, soon begins to take place, both 
 in the central coagulum and in the membrane of the vesicle. 
 
 The clot, which is at first large, soft, and gelatinous, like any 
 other mass of coagulated blood, begins to contract; and the serum 
 separates from the coagulum proper. The serum, as fast as it 
 separates from the coagulum, is absorbed by the neighboring parts; 
 and the clot, accordingly, grows every day smaller and denser than 
 before. At the same time the coloring matter of the blood under- 
 goes the changes which usually take place in it after extravasation, 
 and is partially reabsorbed together with the serum. This second 
 change is somewhat less rapid than the former, but still a diminu- 
 tion of color is very perceptible in the clot, at the expiration of two 
 weeks. 
 
 The membrane of the vesicle during this time is beginning to 
 undergo a process of hypertrophy or development, by which it 
 becomes thickened and convoluted, and tends to fill up partially 
 the cavity of the follicle. This hypertrophy and convolution of 
 the membrane just named commences and proceeds most rapidly 
 
480 
 
 MENSTRUATION AND PREGNANCY. 
 
 Fig. 171. 
 
 at the deeper part of the follicle, directly opposite the situation of 
 the superficial rupture. From this point it gradually becomes 
 thinner and less convoluted as it approaches the surface of the 
 ovary and the edges of the ruptured orifice. 
 
 At the end of three weeks, this hypertrophy of the membrane of 
 the vesicle has reached its maximum. The ruptured Graafian fol- 
 licle has now become so completely solidified by the new growth 
 above described, and by the condensation of its clot, that it receives 
 the name of the corpus luteum. It forms a perceptible prominence 
 upon the surface of the ovary, and may be felt between the fingers 
 as a well-defined rounded tumor, which is nearly always somewhat 
 flattened from side to side. It measures about three-quarters of an 
 
 inch in length and half an inch in 
 depth. On its surface may be seen a 
 minute cicatrix of the peritoneum, 
 occupying the spot of the original 
 rupture. 
 
 On cutting it open at this time (Fig. 
 171), the corpus luteum is seen to con- 
 sist, as above described, of a central 
 coagulum and a convoluted wall. 
 The coagulum is semi-transparent, of 
 a gray or light greenish color, more 
 or less mottled with red. The con- 
 voluted wall is about one-eighth of 
 an inch thick at its deepest part, and 
 of an indefinite yellowish or rosy 
 hue, not very different in tinge from 
 the rest of the ovarian tissue. The convoluted wall and the con- 
 tained clot lie simply in contact with each other, as at first, without 
 any intervening membrane or other organic connection ; and they 
 may still be readily separated from each other by the handle of a 
 knife or the flattened end of a probe. The corpus luteum at this 
 time may also be stripped out, or enucleated entire, from the ovarian 
 tissue, just as might have been done with the Graafian follicle pre- 
 viously to its rupture. When enucleated in this way, the corpus 
 luteum presents itself under the form of a solid globular or flat- 
 tened tumor, with convolutions upon it somewhat similar in ap- 
 pearance to those of the brain, and covered with the remains of 
 the areolar tissue, by which it was previously connected with the 
 substance of the ovary. . . 
 
 Ovary cut open, showing corpus 
 luteum divided longitudinally; three 
 weeks after menstruation. From a girl 
 dead of hsemoptysis. 
 
COEPUS LUTEUM OF MENSTRUATION. 
 
 481 
 
 Fig. 172. 
 
 Ovary, showing corpus 
 luteum four weeks after men- 
 struation ; from a woman dead 
 of apoplexy. 
 
 After the third week from the close of menstruation, the corpus 
 luteum passes into a retrograde condition. It diminishes percep- 
 tibly in size, and the central coagulum continues to be absorbed 
 and loses still farther its coloring matter. The whole body under- 
 goes a process of partial atrophy ; and at 
 the end of the fourth week it is not more 
 than three-eighths of an inch in its longest 
 diameter. (Fig. 172.) The external cicatrix 
 may still usually be seea, as well as the 
 point where the central coagulum comes 
 in contact with the peritoneum. There 
 is still no organic connection between the 
 central coagulum and the convoluted wall ; 
 but the partial condensation of the clot and 
 the continued folding of the wall prevent the 
 separation of the two being so easily accom- 
 plished as before, though it may still be 
 eflfected by careful management. The entire 
 corpus luteum may also still be extracted 
 from its bed in the ovarian tissue. 
 
 The color of the convoluted wall, during the early part of this 
 retrograde stage, instead of fading, like that of the fibrinous coagu- 
 lum, becomes more strongly marked. From having a dull yellowish 
 or rosy hue, as at first, it gradually assumes a brighter and more 
 decided yellow. This change of color in the convoluted wall is 
 produced in consequence of a kind of fatty degeneration which 
 takes place in its texture ; a large quantity of oil-globules being 
 deposited in it at this time, as may be readily recognized under 
 the microscope. At the end of the fourth 
 week, this alteration in hue is complete ; 
 and the outer wall of the corpus luteum 
 is then of a clear chrome-yellow color, by 
 which it is readily distinguished from all 
 the neighboring tissues. 
 
 After this period, the process of atrophy 
 and degeneration goes on rapidly. The 
 clot becomes constantly more dense and 
 shrivelled, and is soon converted into a 
 minute, stellate, white, or reddish white 
 cicatrix. The yellow wall becomes softer 
 and more friable, as is the case with all 
 31 
 
 Fig. 173. 
 
 ,4:^ 
 
 OvART, showing corpus lu- 
 teum, nine weeks after menstrua- 
 tion ; from a girl dead of tuber- 
 cular meningitis. 
 
482 MENSTEUATION AND PEEGNANCY. 
 
 tissues undergoing fatty degeneration, and shows less distinctly 
 the markings of its convolutions. At the same time, its edges 
 become confounded with the central coagulum on the one hand, 
 and the neighboring tissues on the other, so that it is no longer 
 possible to separate them fairly from each other. At the end of 
 eight or nine weeks the whole body is reduced to the condition of 
 an insignificant, yellowish, cicatrix-like spot, measuring less than a 
 quarter of an inch in its longest diameter, in which the original 
 texture of the corpus luteum can be recognized only by the pecu- 
 liar folding and coloring of its constituent parts. Subsequently its 
 atrophy goes on in a less active manner, and a period of seven or 
 eight months sometimes elapses before its final and complete dis- 
 appearance. 
 
 The corpus luteum, accordingly, is a formation which results 
 from the filling up and obliteration of a ruptured Graafian follicle. 
 Under ordinary conditions, a corpus luteum is produced at every 
 menstrual period ; and notwithstanding the rapidity with which it 
 retrogrades and becomes atrophied, a new one is always formed 
 before its predecessor has completely disappeared. 
 
 When, therefore, we examine the ovaries of a healthy female, in 
 whom the menses have recvirred with regularity for some time 
 previous to death, several corpora lutea will be met with in different 
 stages of formation and atrophy. Thus we have found, under such 
 circumstances, four, five, six, and even eight corpora lutea in the 
 ovaries at the same time, perfectly distinguishable by their texture, 
 but very small, and most of them evidently in a state of advanced 
 retrogression. They finally disappear altogether, and the number 
 of those present in the ovary, therefore, no longer corresponds with 
 that of the Graafian follicles which have been ruptured. 
 
 II. CORPUS LUTEUM OF PREGNANCY. 
 
 Since the process above described takes place at every menstrual 
 period, it is independent of impregnation and even of sexual inter- 
 course. The mere presence of a corpus luteum, therefore, is no 
 indication that pregnancy has existed, but only that a Graafian 
 follicle has been ruptured, and its contents discharged. We find, 
 nevertheless, that when pregnancy does take place, the appearance 
 of the corpus luteum becomes so much altered as to be readily dis- 
 tinguished from that which simply follows the ordinary menstrual 
 
CORPUS LUTEUM OF PREGNANCY. 483 
 
 process. It is proper, therefore, to speak of two kinds of corpora 
 lutea; one belonging to menstruation, the other to pregnancy. 
 
 The difference between these two kinds of corpora lutea is not 
 an essential or fundamental difference ; since they both originate 
 in the same way, and are composed of the same structures. It 
 is, properly speaking, only a difference in the degree and rapidity 
 of their development. For while the corpus luteum of menstrua- 
 tion passes rapidly through its different stages, and is very soon 
 reduced to a condition of atrophy, that of pregnancy continues its 
 development for a long time, attains a larger size and firmer organ- 
 ization, and disappears finally only at a much later period. 
 
 This variation in the development and history of the corpus 
 luteum depends upon the unusually active condition of the pregnant 
 uterus. This organ exerts a powerful sympathetic action, during 
 pregnancy, upon many other parts of the system. The stomach 
 becomes irritable, the appetite capricious, and even the mental 
 faculties and the moral disposition are frequently more or less 
 affected. The ovaries, however, feel the disturbing influences of 
 gestation more certainly and decidedly than the other organs, since 
 they are more closely connected with the uterus in the ordinary 
 performance of their function. The moment that pregnancy takes 
 place, the process of menstruation is arrested. No more eggs come 
 to maturity and no more Graafian follicles are ruptured, during the 
 whole period of gestation. It is not at all singular, therefore, that 
 the growth of the corpus luteum should also be modified, by an 
 influence which affects so profoundly the system at large, as well 
 as the ovaries in particular. 
 
 During the first three weeks of its formation, the growth of the 
 corpus luteum is the same, in the impregnated, as in the unimpreg- 
 nated condition. After that time, however, a difference becomes 
 manifest. Instead of commencing a retrograde course during the 
 fourth week, the corpus luteum of pregnancy continues its deve- 
 lopment. The external wall grows thicker, and its convolutions 
 more abundant. Its color alters in the same way as previously 
 described, and becomes of a bright yellow by the deposit of fatty 
 matter in microscopic globules and granules. 
 
 By the end of the second month, the whole corpus luteum has in- 
 creased in size to such an extent as to measure seven-eighths of an 
 inch in length by half an inch in depth. (Fig. 174.) The central 
 coagulum has by this time become almost entirely decolorized, so as 
 
484 
 
 MENSTRUATION AND PREGNANCY. 
 
 to present the appearance of a purely fibrinous deposit. Sometimes 
 we find that a part of the serum, during its separation from the clot, 
 has accumulated in the centre of the mass, as in Fig. 174, forming a 
 little cavity containing a few drops of clear fluid and inclosed by a 
 whitish, fibrinous layer, the remains of the solid portion of the clot. 
 
 It is this fibrinous layer 
 ^ig- l'''^- which has sometimes been 
 
 mistaken for a distinct or- 
 ganized membrane, lining 
 the internal surface of the 
 convoluted wall, and which 
 has thus led to the belief 
 that the yellow matter of 
 the corpus luteum is nor- 
 mally deposited outside the 
 membrane of the Graafian 
 follicle. Such,- however, is 
 not its real structure. The convoluted wall of the corpus luteum 
 is the membrane of the follicle itself, partially altered by hyper- 
 trophy, as may be readily seen by examination in the earlier stages 
 of its growth ; and the fibrinous layer, situated internally, is the 
 original bloody coagulum, decolorized and condensed by continued 
 absorption. The existence of a central cavity, containing serous 
 fluid, is merely an occasional, not a constant phenomenon. More 
 frequently, the fibrinous clot is solid throughout, the serum being 
 gradually absorbed, as it separates spontaneously from the coagulum. 
 
 During the third and fourth 
 
 CoRPns Ll'TECM of pi'egnancy, at end of second 
 mouth : from a woman dead from induced abortion. 
 
 Fig. 175. 
 
 Corpus Luteum of pregnancy, at end ■>( fourth 
 month ; from a woman dead by poison. 
 
 months, the enlargement of the 
 corpus luteum continues; so 
 that at the end of that time it 
 may measure seven-eighths of 
 an inch in length by three- 
 quarters of an inch in depth. 
 (Fig. 175.) The convoluted 
 wall is still thicker and more 
 highly developed than before, 
 having a thickness, at its deep- 
 est part, of three sixteenths of 
 an inch. Its color, however, has 
 already begun to fade, and is 
 
COKPUS LUTEUM OF PEEGNANCY. 
 
 485 
 
 Fig. 176. 
 
 now of a dull yellow, instead of the bright, clear tinge which it 
 previously exhibited. The central coagulum, perfectly colorless 
 and fibrinous in appearance, is often so much flattened out, by the 
 lateral compression of its mass, that it has hardly a line in thickness. 
 The other relations of the different parts of the corpus luteum 
 remain the same. 
 
 The corpus luteum has now attained its maximum of develop- 
 ment, and remains without any very perceptible alteration during 
 the fifth and sixth months. It then begins to retrograde, diminish- 
 ing constantly in size during the seventh and eighth months. Its 
 external wall fades still more perceptibly in color, becoming of a 
 faint yellowish white, not unlike that which it presented at the end 
 of the third week. Its texture is thick, soft, and elastic, and it is 
 still strongly convoluted. An abundance of fine red vessels can be 
 seen penetrating from the exterior into the interstices of its con- 
 volutions. The central coagulum is reduced by this time to the 
 condition of a whitish, radiated cicatrix. 
 
 The atrophy of the organ continues during the ninth month. 
 At the termination of pregnancy, it is re- 
 duced to the size of half an inch in length 
 and three-eighths of an inch in depth. 
 (Fig. 176.) It is then of a faint indefinite 
 hue, but little contrasted with the remain- 
 ing tissues of the ovary. The central cica- 
 trix has become very small, and appears 
 only as a thin whitish lamina with radiating 
 processes which run in between the inter- 
 stices of the convolutions. The whole mass, 
 however, is still quite firm and resisting to 
 the touch, and is readily distinguishable, 
 both from its size and texture, as a pro- 
 minent feature in the ovarian tissue, and a 
 reliable indication of pregnancy. The con- 
 voluted structure of its external wall is 
 very perceptible, and the point of rupture, 
 with its external peritoneal cicatrix, distinctly visible. 
 
 After delivery, the corpus luteum retrogrades rapidly. At the 
 end of eight or nine weeks, it has become so much altered that its 
 color is no longer distinguishable, and only faint traces of its con- 
 voluted structure are to be discovered by close examination. These 
 
 Corpus Lpteum of preg- 
 nancy, at term ; from a woman 
 dead in delivery from rupture 
 of the uterus. 
 
486 MENSTRUATION AND PREGNANCY. 
 
 traces may remain, however, for a long time afterward, more or less 
 concealed in the ovarian tissue. We have distinguished them so 
 late as nine and a half months after delivery. They finally disap- 
 pear entirely, together with the external cicatrix which previously 
 marked their situation. 
 
 During the existence of gestation, the process of menstruation 
 being suspended, no new follicles are ruptured, and no new corpora 
 lutea produced ; and as the old ones, formed before the period of 
 conception, gradually fade and disappear, the corpus luteum which 
 marks the occurrence of pregnancy after a short time exists alone 
 in the ovary, and is not accompanied by any others of older date. 
 In twin pregnancies, we of course find two corporea lutea in the 
 ovaries ; but these are precisely similar to each other, and, being 
 evidently of the same date, will not give rise to any confusion. 
 Where there is but a single foetus in the uterus, and the ovaries 
 contain two corpora lutea of similar appearance, one of them 
 belongs to an embryo which has been blighted by some accident 
 in the early part of pregnancy. The remains of the blighted em- 
 bryo may often be discovered, in such cases, in some part of the 
 Fallopian tubes, where it has been arrested in its descent toward 
 the uterus. 
 
 After the process of lactation comes to an end, the ovaries again 
 resume their ordinary function. The Graafian follicles mature and 
 rupture in succession, as before, and new corpora lutea follow each 
 other in alternate development and disappearance. 
 
 We find, then, that the corpus luteum of menstruation differs from 
 that of pregnancy in the extent of its development and the dura- 
 tion of its existence. While the former passes through all the im- 
 portant phases of its growth and decline in the period of two 
 months, the latter lasts for from nine to ten months, and presents, 
 during a great portion of the time, a larger size and a more solid 
 organization. It will be observed that, even with the corpus luteum 
 of pregnancy, the bright yellow color, which is so important a cha- 
 racteristic, is only temporary in its duration ; not making its appear- 
 ance till about the end of the fourth week, and disappearing after 
 the sixth month. 
 
 The following table contains, in a brief form, the characters of 
 the corpus luteum, as belonging to the two different conditions of 
 menstruation and pregnancy, corresponding with different periods 
 of its development. 
 
CORPUS LUTEUM OF PREGNANCY. 
 
 487 
 
 At the end of 
 three weeks 
 One month 
 
 Two months 
 
 Six months 
 
 Nine months 
 
 CoKPus Ldteum of Menstruation. Corpus Luteum of Pregnancy. 
 Three-quarters of an inch in diameter ; central clot reddish ; con- 
 voluted wall pale. 
 
 Smaller; convoluted wall bright 
 yellow ; clot still reddish. 
 
 Reduced to the condition of an 
 insignificant cicatrix. 
 
 Absent. 
 
 Absent. 
 
 Larger; convoluted wall bright 
 yellow ; clot still reddish. 
 
 Seven-eighths of an inch in dia- 
 meter; convoluted wall bright 
 yellow; clot perfectly decolor- 
 ized. 
 
 Still as large as at end of second 
 month; clot fibrinous; convo- 
 luted wall paler. 
 
 One-half an inch in diameter ; 
 central clot converted into a 
 radiating cicatrix ; the external 
 wall tolerably thick and convo- 
 luted, but without any bright 
 yellow color. 
 
488 DEVELOPMENT OF THE IMPREGNATED EGG. 
 
 CHAPTER VII. 
 
 ON THE DEVELOPMENT OF THE IMPREGNATED EGG 
 —SEGMENTATION OF THE VI T EL L US— BL A STODER- 
 MIC MEMBRANE — FORMATION OF ORGANS IN THE 
 FROG. 
 
 We have seen, in the foregoing chapters, how the egg, produced 
 in the ovarian follicle, becomes gradually developed and ripened, 
 until it is ready to be discharged. The egg, accordingly, passes 
 through several successive stages of formation, even while still con- 
 tained within the ovary; and its vitellus becomes gradually com- 
 pleted, by the formation of albuminous material and the deposit of 
 molecular granulations. The last change which the egg undergoes, 
 in this situation, and which marks its complete maturity, is the dis- 
 appearance of the germinative vesicle. This vesicle, which is, in 
 general, a prominent feature of the ovarian egg, disappears but a 
 short time previous to its discharge, or even just at the period of 
 its leaving the Graafian follicle. 
 
 The egg, therefore, consisting simply of the mature vitellus and 
 the vitelline membrane, comes in contact, after leaving the ovary, 
 and while passing through the Fallopian tube, with the spermatic 
 fluid, and thereby becomes fecundated. By the influence of fecun- 
 dation, a new stimulus is imparted to its growth ; and while the 
 vitality of the unimpregnated germ, arrived at this point, would 
 have reached its termination, the fecundated egg, on the contrary, 
 starts upon a new and more extensive course of development, by 
 which it is finally converted into the body of the young animal. 
 
 The egg, in the first place, as it passes down the Fallopian tube, 
 becomes covered with an albuminous secretion. In the birds, as we 
 have seen, this secretion is very abundant, and is deposited in suc- 
 cessive layers around the vitellus. In the reptiles, it is also poured 
 out in considerable quantity, and serves for the nourishment of the 
 egg during its early growth. In quadrupeds, the albuminous matter 
 is supplied in the same way, though in smaller quantity, by the 
 
SEGMENTATION OF THE VITELLUS. 
 
 489 
 
 mucous membrane of the Fallopian tubes, and envelopes the egg in 
 a layer of nutritious material. 
 
 A very remarkable change now takes place in the impregnated egg, 
 which is known as the spontaneous division, or segyneiitation, of the 
 vitellus. A furrow first shows itself, 
 running round the globular mass of the 
 vitellus in a vertical direction, which 
 gradually deepens until it has divided 
 the vitellus into two separate halves or 
 hemispheres. (Fig. 177, a.) Almost at 
 the same time another furrow, running 
 at right angles with the first, penetrates 
 also the substance of the vitellus and 
 cuts it in a transverse direction. The 
 vitellus is thus divided into four equal 
 portions (Fig. 177, b), the edges and 
 angles of which are rounded off, and 
 which are still contained in the cavity 
 of the vitelline membrane. The spaces 
 between them and the internal surface 
 of the vitelline membrane are occu- 
 pied by a transparent fluid. 
 
 The process thus commenced goes 
 on by a successive formation of fur- 
 rows and sections, in various direc- 
 tions. The four vitelline segments 
 already produced are thus subdivided 
 into sixteen, the sixteen into sixty- 
 four, and so on; until the whole vi- 
 tellus is converted into a mulberry 
 shaped mass, composed of minute, 
 nearly spherical bodies, which are 
 called the "vitelline spheres." (Fig. 
 177, c.) These vitelline spheres have 
 a somewhat firmer consistency than 
 the original substance of the vitellus; 
 and this consistency appears to in- 
 crease, as they successively multiply 
 in numbers and diminish in size. At last they have become so 
 abundant as to be closely crowded together, compressed into poly- 
 gonal forms, and flattened against the internal surface of the vitel- 
 
 Segmextation of the Vitellus. 
 
490 DEVELOPMENT OF THE IMPREGNATED EGG. 
 
 line membrane. (Fig. 177, d) They have by this time been con- 
 verted into true animal cells; and these cells, adhering to each other 
 by their adjacent edges, form a continuous organized membrane, 
 which is termed the Blastodermic mewhrane. 
 
 During the formation of this membrane, moreover, the egg, while 
 passing through the Fallopian tubes into the uterus, has increased 
 in size. The albuminous matter with which it was enveloped has 
 liquefied; and, being absorbed by endosmosis through the vitelline 
 membrane, has furnished the materials for the more solid and ex- 
 tensive growth of the newly-formed structures. It may also be 
 seen that a large quantity of this fluid has accumulated in the 
 central cavity of the egg^ inclosed accordingly by the blastodermic 
 membrane, with the original vitelline membrane still forming an 
 external envelope round the whole. 
 
 The next change which takes place, consists in the division or 
 splitting of the blastodermic membrane into two layers, which are 
 known as the external and internal layers of the blastodermic membrane. 
 They are both still composed exclusively of cells ; but those of the 
 external layer are usually smaller and more compact, while those 
 of the internal are rather larger and looser in texture. The egg 
 ihen presents the appearance of a globular sac, the walls of which 
 consist of three concentric layers, lying in contact with and inclos- 
 ing each other, viz., 1st, the structureless vitelline membrane on the 
 outside ; 2d, the external layer of the blastodermic membrane, com- 
 posed of cells ; and 3d, the internal layer of the blastodermic mem- 
 brane, also composed of cells. The cavity of the egg is occupied 
 by a transparent fluid, as above mentioned. 
 
 This entire process of the segmentation of the vitellus and the 
 formation of the blastodermic membrane is one of the most re- 
 markable and important of all the changes which take place during 
 the development of the egg. It is by this process that the simple 
 globular mass of the vitellus, composed of an albuminous matter 
 and oily granules, is converted into an organized structure. For 
 the blastodermic membrane, though consisting only of cells nearly 
 uniform in size and shape, is nevertheless a truly organized mem- 
 brane, made up of fully formed anatomical elements. It is, more- 
 over, the first sign of distinct organization which makes its appear- 
 ance in the egg; and as soon as it is completed, the body of the 
 new foetus is formed. The blastodermic membrane is, in fact, the 
 body of the foetus. It is at this time, it is true, exceedingly simple 
 in texture ; but we shall see hereafter that all the future organs 
 
BLASTODERMIC MEMBRANE. 491 
 
 of the body, however varied and complicated in structure, arise out 
 of it, by modification and development of its different parts. 
 
 The segmentation of the vitellus, moreover, and the formation 
 of the blastodermic membrane, take place in essentially the same 
 manner in all the different classes of animals. It is always in this 
 way that the egg commences its development, whether it be des- 
 tined to form afterward a fish or a reptile, a bird, a quadruped or a 
 man. The peculiarities belonging to different species show them- 
 selves afterward, by variations in the manner and extent of the 
 development of different parts. In the higher animals and in the 
 human subject the development of the egg becomes an exceedingly 
 complicated process, owing to the formation of various accessory 
 organs, which are made requisite by the peculiar conditions under 
 which the development of the embryo takes place. It is, in fact, 
 impossible to describe or understand properly the complex embry- 
 ology of the quadrupeds, and more particularly that of the human 
 subject, without first tracing the development of those species in 
 which the process is more simple. We shall commence our descrip- 
 tion, therefore, with the development of the egg of the frog, which 
 is for many reasons particularly appropriate for our purpose. 
 
 The egg of the frog, when discharged from the body of the female 
 and fecundated by the spermatic fluid of the male, is deposited in 
 the water, enveloped in a soft elastic cushion of albuminous sub- 
 stance. It is therefore in a situation where it is freely exposed to 
 the light, the air, and the moderate warmth of the sun's rays, and 
 where it can absorb directly an abundance of moisture and of ap- 
 propriate nutritious material. We find accordingly that under 
 these circumstances the development of the egg is distinguished 
 by a character of great simplicity ; since the whole of the vitellus is 
 directly converted into the body of the embryo. There are no accessory 
 organs required, and consequently no complication of the formative 
 process. 
 
 The two layers of the blastodermic membrane, above described, 
 represent together the commencement of all the organs of the foetus. 
 They are intended, however, for the production of two different 
 systems ; and the entire process of their development may be ex- 
 pressed as follows : The external layer of the blastodermic membrane 
 produces the spinal column and all the organs of animal life; while the 
 internal layer produces the intestinal canal, and all the organs of vege- 
 tative life. 
 
 The first sign of advancing organization in the external layer of 
 
492 DEVELOPMENT OF THE IMPREGNATED EGG. 
 
 the blastodermic membrane shows itself in a thickening and con- 
 densation of its structure. This thickened portion has the form of an 
 elongated oval-shaped spot, termed the "embryonic spot" (Fig. 178), 
 
 the wide edges of which are somewhat 
 more opaque than the rest of the blasto- 
 dermic membrane. Inclosed within 
 these opaque edges is a narrower color- 
 less and transparent space, the "area 
 pellucida," and in its centre is a delicate 
 line, or furrow, running longitudinally 
 from front to rear, which is called the 
 " primitive trace." 
 
 On each side of the primitive trace, 
 1.VPREGXATEI, E G r, , with com- ^^ thc arca pellucida, the substance of 
 mencement of forniaiion of embryo: |;}]e blastodermic membrane riscs up in 
 
 shoTving erabrvonic spot, area pellu- „ , 
 
 cida, and primuive trace. such a manner as to torm two nearly 
 
 parallel vertical plates or ridges, which 
 approach each other over the dorsal aspect of the fcetus and are 
 therefore called the "dorsal plates." They at last meet on the 
 median line, so as to inclose the furrow above described and con- 
 vert it into a canal. This afterward becomes the spinal canal, and 
 in its cavity is formed the spinal cord, by a deposit of nervous 
 matter upon its internal surface. At the anterior extremity of this 
 canal, its cavity is large and rounded, to accommodate the brain 
 and medulla oblongata; at its posterior extremity it is narrow and 
 pointed, and contains the extremity of the spinal cord. 
 
 In a transverse section of the egg at this stage (Fig. 179), the 
 dorsal plates may be seen approaching each other above, on each 
 side of the primitive furrow or "trace." At a more advanced 
 period (Fig. 180) they may be seen fairly united with each other, 
 so as to inclose the cavity of the spinal canal. At the same time, 
 the edges of the thickened portion of the blastodermic membrane 
 grow outward and downward, so as to spread out more and more 
 over the lateral portions of the vitelline mass. These are called 
 the "abdominal plates;" and as they increase in extent they tend 
 to unite with each other below and inclose the abdominal cavity, 
 just as the dorsal plates unite above, and inclose the spinal canal. 
 At last the abdominal plates actually do unite with each other on 
 the median line (at i. Fig. 180), embracing of course the whole 
 internal layer of the blastodermic membrane (5), which incloses in 
 
FORMATION OF ORGANS. 
 
 498 
 
 its turn the remains of the original vitellus and the albuminous 
 fluid which has accumulated in its cavity. 
 
 Fig. 179. 
 
 Fig. 180. 
 
 Transverse section of Egg in an early 
 stage of development — 1. External layer 
 of blastodermic membrane. 2,2. Dorsal 
 plates. 3. Internal layer of blastodermic 
 membrane. 
 
 1 .MPREG N.A.TED EoQ, at a SOmeTvhHt 
 more advanced period. — 1. Umbilicus, or 
 point of union between abdominal plates. 
 2, 2. Dorsal plates united -with each other 
 on the median line and inclosing the spinal 
 canal. 3, 3. Abdominal plates. 4. Sec- 
 tion of spinal column, with laminae and 
 ribs. 5. Internal layer of blastodermic 
 membrane. 
 
 During this time, there is formed, in the thickness of the external 
 blastodermic layer, immediately beneath the spinal canal, a longitu- 
 dinal cartilaginous cord, called the "chorda dorsalis." Around the 
 chorda dorsalis are afterward developed the bodies of the vertebrae 
 (Fig. 180, 4), forming the chain of the vertebral column; and the 
 oblique processes of the vertebrae run upward from this point into the 
 dorsal plates ; while the transverse processes, and ribs, run outward 
 and downward in the abdominal plates, to encircle more or less 
 completely the corresponding portion of the body. 
 
 If we now examine the egg in longitudinal section, while this 
 process is going on, the thickened portion of the external blastoder 
 mic layer may be seen in profile, as at i, Fig. 181. The anterior 
 portion (2), which will form the head, is thicker than the posterior 
 (3), Avhich will form the tail of the young animal. As the whole 
 mass grows rapidly, both in the anterior and posterior direction, 
 the head becomes very thick and voluminous, while the tail also 
 begins to project backward, and the whole egg assumes a distinctly 
 elongated form. (Fig. 182.) The abdominal plates at the same time- 
 meet upon its under surface, and the point at which they finally 
 
494 
 
 DEYELOPMENT OF THE IMPREGNATED EGG. 
 
 unite forms the abdominal cicatrix or umbilicus. The internal blas- 
 todermic layer is seen, of course, in the longitudinal section of the 
 
 Fie. 181. 
 
 Fig. 182. 
 
 Diagram of Frog's Egg, in an parly E(jg of Frog, in process of develop- 
 
 Rfage of development ; longitudinal sec- meui. 
 
 tiou. — 1 Thickened portion of external 
 blastodermic layer, forming body of foetus. 
 2. Anterior extremity of foetus. .3. Poste- 
 rior extremity. 4. Internal layer of blas- 
 todermic membrane. 5. Cavity of vitellus. 
 
 egg, as well as in the transverse, embraced by the abdominal plates, 
 and inclosing, as before, the renaains of the vitellus. 
 
 As the development of the above parts goes on (Fig. 183), the 
 head becomes still larger, and soon shows traces of the formation 
 
 Fig. 183. 
 
 OF Frog, farther advanced. 
 
 of organs of special sense. The tail also increases in size, and pro- 
 jects farther from the posterior extremity of the embryo. The 
 spinal cord runs in a longitudinal direction from front to rear, and 
 its anterior extremity enlarges, so as to form the brain and medulla 
 oblongata. In the mean time, the internal blastodermic layer, which 
 is subsequently to be converted into the intestinal canal, has been 
 shut in by the abdominal walls, and still forms a perfectly closed 
 sac, of a slightly elongated figure, without either inlet or outlet. 
 Afterward, the mouth is formed by a process of atrophy and per- 
 ibration, which takes place through both external and internal layers, 
 at the anterior extremity, while a similar perforation, at the poste- 
 rior extremity, results in the formation of the anus. 
 
FORMATION OF ORGANS. 495 
 
 All these parts, however, are as yet imperfect; and, being merely 
 in the course of formation, are incapable of performing any active 
 function. 
 
 By a continuation of the same process, the different portions of 
 the external blastodermic layer are further developed, so as to re- 
 sult in the complete formation of the various parts of the skeleton, 
 the integument, the organs of special sense, and the voluntary 
 nerves and muscles. The tail at the same time acquires sufficient 
 size and strength to be capable of acting as an organ of locomo- 
 tion. (Fig. 184.) The intestinal canal, which has been formed from 
 
 Fig. 184. 
 
 T A B p o L E fully developed. 
 
 the internal blastodermic layer, is at first a short, wide, and nearly 
 straight tube, running directly from the mouth to the anus. It 
 soon, however, begins to grow faster than the abdominal cavity 
 which incloses it, becoming longer and narrower, and is at the same 
 time thrown into numerous convolutions. It thus presents a larger 
 internal surface for the performance of the digestive process. 
 
 Arrived at this period, the young tadpole ruptures the vitelline 
 membrane, by which he has heretofore been inclosed, and leaves the 
 cavity of the egg. He at first fastens himself upon the remains of 
 the albuminous matter deposited round the egg, and feeds upon it for 
 a short period. He soon, however, acquires sufficient strength and 
 activity to swim about freely in search of other food, propelling 
 himself by means of his large, membranous, and muscular tail. 
 The alimentary canal increases very rapidly in length and becomes 
 spirally coiled up in the abdominal cavity, so as to attain a length 
 from seven to eight times greater than that of the entire body. 
 
 After a time, a change takes place in the external form of the 
 young animal. Anterior and posterior extremities or limbs begin to 
 show themselves, by budding or sprouting from the corresponding 
 regions of the body. (Fig. 185.) At first these organs are very 
 small, imperfect in structure, and altogether useless for purposes of 
 
496 
 
 DEVELOPMENT OF THE IMPREGNATED EGG. 
 
 locomotion. Thej soon, however, increase in size and strength ; 
 and while thej keep pace with the increasing development of the 
 whole body, the tail on the contrary ceases to grow, and becomes 
 shrivelled and atrophied. The limbs, in fact, are destined finally 
 to replace the tail as organs of locomotion ; and a time at last 
 arrives (Fig. 186) when the tail has altogether disappeared, while 
 
 Fig. 185. 
 
 Fisj. 186. 
 
 Tadpole, with limbs begiuoiug to be formed. 
 
 Perfect Frog. 
 
 the legs have become fully developed, muscular and powerful. 
 Then the animal, which was before confined to an aquatic mode 
 of life, becomes capable of living also upon land, and a trans- 
 formation is effected from the tadpole into the perfect frog. 
 
 During the same time, other changes of an equally important 
 character have taken place in the internal organs. The tadpole at 
 first breathes by gills; but these organs subsequently become 
 atrophied and disappear, being finally replaced by well developed 
 lungs. The structure of the mouth, also, of the integument, and 
 of the circulatory system, is altered to correspond with the varying 
 conditions and wants of the growing animal ; and all these changes, 
 taking place in part successively and in part simultaneously, bring 
 the animal at last to a state of complete formation. 
 
 The process of development may then be briefly recapitulated as 
 follows: — 
 
 1. The blastodermic membrane, produced by the segmentation 
 of the vitellus, consists of two cellular layers, viz., an external and 
 an internal blastodermic layer. 
 
 2. The external layer of the blastodermic membrane incloses by 
 its dorsal plates the cerebro-spinal canal, and by its abdominal 
 plates the abdominal or visceral cavity. 
 
FORMATION OF ORGANS IN THE FROG. 497 
 
 3. The internal layer of the blastodermic membrane forms the 
 intestinal canal, which becomes lengthened and convoluted, and 
 communicates with the exterior by a mouth and anus of secondary 
 formation. 
 
 4. Finally the cerebro-spinal axis and its nerves, the skeleton, 
 the organs of special sense, the integument, and the muscles, are 
 developed from the external blastodermic layer ; while the anterior 
 and posterior extremities are formed from the same layer by a pro- 
 cess of sprouting, or continuous growth. 
 
 32 
 
498 
 
 THE UMBILICAL VESICLE. 
 
 CHAPTER VIII. 
 
 THE UMBILICAL VESICLE, 
 
 Fig. 187. 
 
 In" the frog, as we have seen, the abdominal plates, closing 
 together in front and underneath the body of the animal, shut in 
 directly the whole of the vitellus, and join each other upon the 
 median line, at the umbilicus. The whole remains of the vitellus 
 are then inclosed in the abdomen of the animal, and in the intestinal 
 sac formed by the internal blastodermic layer. 
 
 In many instances, however, as, for example, in several kinds of 
 fish, and in all the birds and quadrupeds, the abdominal plates do 
 
 not immediately embrace the whole of 
 the vitelline mass, but tend to close 
 together about its middle ; so that the 
 vitellus is constricted, in this way, and 
 divided into two portions: one internal, 
 and one external. (Fig. 187.) As the 
 process of development proceeds, the body 
 of the foetus increases in size, out of pro- 
 portion to the vitelline sac, and the con- 
 striction just mentioned becomes at the 
 same time more strongly marked ; so that 
 the separation between the internal and external portions of the 
 vitelline sac is nearly complete. (Fig. 188.) The internal layer of 
 the blastodermic membrane is by the same means divided into 
 two portions, one of which forms the intestinal canal, while the 
 other, remaining outside, forms a sac-like appendage to the abdo- 
 men, which is known by the name of the umbilical vesicle. 
 
 The umbilical vesicle is accordingly lined by a portion of the 
 internal blastodermic layer, continuous with the mucous membrane 
 of the intestinal canal; while it is covered on the outside by a por- 
 tion of the external blastodermic layer, continuous with the integu- 
 ment of the abdomen. 
 
 EfiQOF Fish; showing forma 
 tioa of umbilical vesicle. 
 
THE UMBILICAL VESICLE. 499 
 
 After the young animal leaves the egg, the umbilical vesicle 
 sometimes becomes withered and atrophied by the absorption of its 
 contents; while in some instances, the abdominal walls gradually 
 
 Fig. 188. 
 
 Young Fish with umbilical vesicle. 
 
 extend over it, and crowd it back into the abdomen ; the nutritious 
 matter which it contained passing from the cavity of the vesicle 
 into that of the intestine by the narrow passage or canal which 
 remains open between them. 
 
 In the human subject, however, as well as in the quadrupeds, the 
 umbilical vesicle becomes more completely separated from the abdo 
 men than in the cases just mentioned. There is at first a wide com- 
 munication between the cavity of the umbilical vesicle and that of 
 the intestine ; and this communication, as in other instances, becomes 
 gradually narrowed by the increasing constriction of the abdominal 
 walls. Here, however, the constriction proceeds so far that the 
 opposite surfaces of the canal come in contact with each other, and 
 adhere; so that the narrow passage previously 
 existing between the cavity of the intestine 
 and that of the umbilical vesicle is obliterated, 
 and the vesicle is then connected with the 
 abdomen only by an impervious cord. This 
 cord afterward elongates, and becomes con- 
 verted into a slender, thread-like pedicle (Fig. 
 189), passing out from the abdomen of the 
 foetus, and connected by its further extremity 
 with the umbilical vesicle, which is filled with 
 a transparent, colorless fluid. The umbilical human embryo, with 
 
 .,. T- 1 ••II- 11 umbilical vesicle ; about the 
 
 vesicle is very distinctly visible m the human gfth week. 
 
 foetus so late as the end of the third month. 
 
 After that period it diminishes in size, and is gradually lost in the 
 
 advancing development of the neighboring parts. 
 
 In the formation of the umbilical vesicle, we have the first varia- 
 
500 THE UMBILICAL VESICLE. 
 
 tion from the simple plan of development described in the preceding 
 chapter. Here, the whole of the vitellus is not directly converted 
 into the body of the embryo ; but while a part of it is taken, as 
 usual, into the abdominal cavity, and used immediately for the pur- 
 poses of nutrition, a part is left outside the abdomen, in the umbilical 
 vesicle, a kind of secondary organ or appendage of the foetus. The 
 contents of the umbilical vesicle, however, are afterward absorbed, 
 and so appropriated, finally, to the nourishment of the newly formed 
 tissues 
 
AMNION AND ALLANTOIS. 501 
 
 CHAPTER IX. 
 
 AMNION AND A LL A NTOIS. — D E VE LO P M E N T OF 
 THE CHICK. 
 
 We shall now proceed to the description of two other accessory 
 organs, which are formed, during the development of the fecundated 
 egg, in all the higher classes of animals. These are the amnion and 
 the allantois ; two organs which are always found in company with 
 each other, since the object of the first is to provide for the forma- 
 tion of the second. The amnion is formed from the external layer 
 of the blastodermic membrane, the allantois from the internal layer. 
 
 In the frog and in fish, as we have seen, the egg is abundantly 
 supplied with moisture, air, and nourishment, by the water with 
 which it is surrounded. It can absorb directly all the gaseous and 
 liquid substances, which it requires for the purposes of nutrition 
 and growth. The absorption of oxygen, the exhalation of carbonic 
 acid, and the imbibition of albuminous and other liquids, can all 
 take place without diflSculty through the simple membranes of the 
 egg; particularly as the time required for the formation of the 
 embryo is very short, and as a great part of the process of develop- 
 ment remains to be accomplished after the young animal leaves 
 the egg. 
 
 But in birds and quadrupeds, the time required for the develop- 
 ment of the foetus is longer. The young animal also acquires a 
 much more perfect organization during the time that it remains 
 inclosed within the egg; and the processes of absorption and exhala- 
 tion necessary for its growth, being increased in activity to a corre- 
 sponding degree, require a special organ for their accomplishment. 
 This special organ, destined to bring the blood of the fcetus into 
 relation with the atmosphere and external sources of nutrition, is 
 the allantois. 
 
 In the frog and the fish, the internal blastodermic layer, forming 
 the intestinal mucous membrane, is inclosed everywhere, as above 
 described, by the external layer, forming the integument; and 
 
502 AMNION AND ALLANTOIS. 
 
 consequently can nowhere come in contact with the investing 
 membrane of the egg. But in the higher animals, the internal 
 blastodermic layer, which is the seat of the greatest vascularity, 
 and which is destined to produce the allantois, is made to come in 
 contact with the external membrane of the egg for purposes of 
 exhalation and absorption ; and this can only be accomplished by 
 opening a passage for it through the external germinative layer. 
 This is done in the following manner, by the formation of the 
 amnion. 
 
 Soon after the body of the foetus has begun to be formed by the 
 thickening of the external layer of the blastodermic membrane, 
 a double fold of this external layer rises up on all sides about 
 the edges of the newly formed enabryo ; so that the body of the 
 foetus appears as if sunk in a kind of depression, and surrounded 
 with a membranous ridge or embankment, as in 
 Fig. 190. The embryo (c) is here seen in profile, 
 with the double membranous folds, above men- 
 tioned, rising up just in advance of the head, 
 and behind the posterior extremity. It must be 
 understood, of course, that the same thing takes 
 place on the two sides of the foetus, by the forma- 
 Diagram of fecpn- tiou of lateral folds simultaneously with the 
 BATED Ego; showing appearance of those in front and behind. As it 
 
 formation of amnion. — ^ i^ 
 
 a. viteiius. 6. External is thcsc folds which are dcstincd to form the 
 LTbra1e.''TBod7of amniou, they are called the "amniotic folds." 
 embryo d,rf. Amniotic The amuiotic folds contiuue to grow, and ex- 
 
 folds. e. Vitelline mem- . t .■, -, n jt_i j j ^ j. ^^ 
 
 ^jj^^g tend themselves lorward, backward and laterally, 
 
 until they approach each other at a point over 
 the back of the foetus (Fig. 191), which is termed the "amniotic 
 umbilicus." Their opposite edges afterward actually come in con- 
 tact with each other at this point, and adhere together, so as to 
 shut in a space or cavity (Fig. 191, b) between their inner surface 
 and the body of the foetus. This space, which is filled with a clear 
 fluid, is called the amniotic cavity. At the same time, the intestinal 
 canal has begun to be formed, and the umbilical vesicle has been 
 partially separated from it, by the constriction of the abdominal 
 walls on the under surface of the body. 
 
 There* now appears a prolongation or diverticulum (Fig. 191, c) 
 o-rowincr out from the posterior portion of the intestinal canal, and 
 following the course of the amniotic fold which has preceded it ; 
 occupying, as it gradually enlarges and protrudes, the space left 
 
AMNION AND ALLANTOIS. 
 
 503 
 
 Fecundated Eon, 
 farther advanced. — a. 
 Umbilical vesicle. h. 
 Amniotic cavity, c. Al- 
 laatois. 
 
 vacant by the rising up of the amniotic fold. This diverticulum 
 is the commencement of the allantois. It is an elongated mem- 
 branous sac, continuous with the posterior portion of the intestine, 
 and containing bloodvessels derived from those 
 of the intestinal circulation. The cavity of the 
 allantois is also continuous with the cavity of 
 the intestine. 
 
 After the amniotic folds have approached and 
 touched each other, as already described, over 
 the back of the foetus, at the amniotic umbilicus, 
 the adjacent surfaces, thus brought in contact, 
 fuse together, so that the cavities of the two 
 folds, coming respectively from front and rear, 
 are separated only by a single membranous par- 
 tition (Fig. 192, c) running from the inner to the 
 outer lamina of the amniotic folds. This parti- 
 tion itself soon after atrophies and disappears; and the inner and 
 outer larainse become consequently separated from each other. The 
 inner lamina (Fig. 192, a) which remains con- 
 tinuous with the integument of the foetus, in- 
 closing the body of the embryo in a distinct 
 cavity, is called the amnion (Fig. 193, h\ and 
 its cavity is known as the amniotic cavity. 
 The outer lamina of the amniotic fold, on the 
 other hand (Fig. 192, h\ recedes farther and 
 farther from the inner, until it comes in con- 
 tact with the original vitelline membrane, still 
 covering the exterior of the egg ; and by con- 
 tinued growth and expansion it at last fuses 
 with the vitelline membrane and unites with 
 its substance, so that the two membranes form 
 but one. This membrane, formed by the fusion 
 and consolidation of two others, constitutes then 
 the external investing membrane of the Qgg. 
 
 The allantois, during all this time, is increas- 
 ing in size and vascularity. Following the course of the amniotic 
 folds as before, it insinuates itself between them, and of course soon 
 comes in contact with the external investing membrane just de- 
 scribed. It then begins to expand laterally in every direction, 
 enveloping more and more the body of the foetus, and bringing its 
 vessels into contact with the external membrane of the egg. 
 
 Fecundated Ego, 
 with allantois nearly com- 
 plete. — a. Inner lamina of 
 amniotic fold. b. Outer la- 
 mina of ditto. c. Point 
 where the amniotic folds 
 come in contact. The allan- 
 tois is seen penetrating be- 
 tween the inner and outer 
 laminse of the amniotic 
 folds. 
 
604 
 
 AMNION AND ALLANTOIS. 
 
 Fig. 193. 
 
 Fecundated Ego, with 
 allantois fully formed. — a. Um- 
 bilical vesicle, b. Amnion, c. 
 Allantois. 
 
 By a continuation of the above process, the allantois at last 
 grows to such an extent as to envelope completely the body of the 
 embryo, together with the amnion: its two 
 extremities coming in contact with each 
 other and fusing together over the back of 
 the foetus, just as the amniotic folds had 
 previously done. (Fig. 193.) It lines, there- 
 fore, the whole internal surface of the in- 
 vesting membrane with a flattened, vascu- 
 lar sac, the vessels of which come from the 
 interior of the body of the foetus, and which 
 still communicates with the cavity of the 
 intestinal canal. 
 
 It is evident, from the above description, 
 that there is a close connection between the 
 formation of the amnion and that of the allantois. For it is only 
 in this manner that the allantois, which is an extension of the in- 
 ternal layer of the blastodermic membrane, can come to be situated 
 outside the foetus and the amnion, and be brought into relation 
 with external surrounding media. The two laminae of the amni- 
 otic folds, in fact, by separating from each other as above described, 
 open a passage for the allantois, and allow it to come in contact 
 with the external membrane of the egg. 
 
 In order to explain more fully the physiological action of the 
 allantois, we shall now proceed to describe the process of develop- 
 ment, as it takes place in the egg of the fowl. 
 
 In order that the embryo may be properly developed in any 
 case, it is essential that it be freely supplied with air, warmth, 
 moisture, and nourishment. The egg of the fowl contains already, 
 when discharged from the generative passages, a sufficient quantity 
 of moisture and albuminous material. The necessary warmth is 
 supplied by the body of the parent during incubation ; while the 
 atmospheric gases can pass and repass through the porous egg- 
 shell, and by endosmosis through the fibrous membranes which 
 line its cavity. 
 
 When the egg is first laid, the vitellus, or yolk, is enveloped in 
 a thick layer of semi-solid albumen. On the commencement of 
 incubation, a liquefaction takes place in the albumen immediately 
 above that part of the vitellus which is occupied by the cicatri- 
 cula ; so that the vitellus rises or floats upward toward the surface 
 by virtue of iis specific gravity, and the cicatricula comes to be 
 
DEVELOPMENT OF THE CHICK. 
 
 505 
 
 placed almost immediately underneath the lining membrane of the 
 egg-shell. As the cicatricula is the spot from which the process of 
 embryonic development commences, the body of the young foetus 
 is by this arrangement placed in the most favorable position for 
 the reception of warmth and other necessary external influences 
 through the egg-shell. The liquefied albumen is also absorbed by 
 the vitelline membrane, and the vitellus thus becomes larger, softer, 
 and more diffluent than before the commencement of incubation. 
 
 As soon as the circulatory apparatus of the embryo has been 
 fairly formed, two minute arteries are seen to run out from its 
 lateral edges and spread out into the neighboring parts of the 
 blastodermic membrane, breaking up into inosculating branches, 
 and covering the adjacent portions of the vitellus with a plexus of 
 capillary bloodvessels. The space occupied in the blastodermic 
 membrane, on the surface of the vitellus, by these vessels, is called 
 the area vasculosa. (Fig. 194.) It is of a nearly circular shape, 
 
 Fig. 194. 
 
 Egg of Fowl during early periods of incubation ; showing the body of the embryo, and the area 
 vasculosa partially covering the surface of the vitellus. 
 
 and is limited, on its outer edge, by a terminal vein or sinus, called 
 the "sinus terminalis." The blood is returned to the body of the 
 foetus by two veins which penetrate beneath its edges, one near the 
 head and one near the tail. 
 
 The area vasculosa tends to increase in extent, as the develop- 
 ment of the foetus proceeds and its circulation becomes more active. 
 It soon covers the upper half, or hemisphere, of the vitellus, and 
 the terminal sinus then runs like an equator round the middle of 
 
506 
 
 AMNION AND ALLANTOIS. 
 
 the vitelline sphere. As the growth of the vascular plexus con- 
 tinues, it passes this point, and embraces more and more of the in- 
 ferior, as well as of the superior hemisphere, the vessels converging 
 toward its under surface, until at last nearly the whole of the 
 vitellus is covered with a network of inosculating capillaries. 
 
 The function of the vessels of the area vasculosa is to absorb 
 nourishment from the cavity of the vitelline sac. As the albumen 
 liquefies during the process of incubation, it passes by endosmosis, 
 more and more abundantly, into the vitelline cavity; the whole 
 vitellus growing constantly larger and more fluid in consistency. 
 The blood of the foetus, then circulating in the vessels of the area 
 vasculosa, absorbs freely the oleagino-albuminous matters of the 
 vitellus, and, carrying them back to the foetus by the returning 
 veins, supplies the newly-formed tissues and organs with abun- 
 dance of nourishment. 
 
 During this period the amnion and the allantois have been also 
 in process of formation. At first the body of the foetus lies upon 
 its abdomen, as in the cases previously described ; but as it increases 
 in size it alters its position so as to lie more upon its side. The 
 allantois then, emerging from the posterior portion of the abdominal 
 cavity, turns directly upward over the body of the foetus, and comes 
 immediately in contact with the shell membrane. (Fig. 195.) It 
 
 Fig. 195. 
 
 Ego of Fowl at a more advanced period of development. The body of the foetus is enveloped 
 by the amnion, and has the umbilical vesicle hanging from its under surface ; while the vascular 
 allantois is seen turning upward and spreading out over the internal surface of the shell-membrane. 
 
 then spreads out rapidly, extending toward the extremities and 
 down the sides of the egg, enveloping more and more completely 
 
DEVELOPMENT OF THE CHICK. 507 
 
 the foetus and the vitelline sac, and taking the place of the albumen 
 which has been liquefied and absorbed. 
 
 It will also be seen, by reference to the figure, that the umbilical 
 vesicle is at the same time formed by the separation of part of the 
 vitellus from the abdomen of the chick; and the vessels of the area 
 vasculosa, which were at first distributed over the vitellus, now 
 ramify, of course, upon the surface of the umbilical vesicle. 
 
 At last the allantois, by its continued growth, envelopes nearly 
 the whole of the remaining contents of the egg ; so that toward the 
 later periods of incubation, at whatever point we break open the 
 egg, we find the internal surface of the shell-membrane everywhere 
 lined with a vascular membranous expansion, supplied by arteries 
 which emerge from the abdomen of the fcBtus. 
 
 It is easy to see, accordingly, with what readiness the absorption 
 and exhalation of gases may take place by means of the allantois. 
 The air penetrates from the exterior through the minute pores of 
 the calcareous shell, and then acts upon the blood in the vessels of 
 the allantois very much in the same manner that the air in the minute 
 bronchial tubes and air- vesicles of the lungs acts upon the blood in 
 the pulmonary capillaries. Examination of the egg, furthermore, 
 at various periods of incubation, shows that changes take place in 
 it which are entirely analogous to the process of respiration. 
 
 The egg, in the first place, during its development, loses water by 
 exhalation. This exhalation is not a simple efl'ect of evaporation, 
 but is the result of the nutritive changes going on in the interior 
 of the egg ; since it does not take place, except in a comparatively 
 slight degree, in unimpregnated eggs, or in those which are not in- 
 cubated, though they may be freely exposed to the air. The ex- 
 halation of fluid is also essential to the processes of development, 
 for it has often been found, in hatching eggs by artificial warmth, 
 that if the air of the chamber in which they are inclosed become 
 unduly charged with moisture, so as to retard or prevent further 
 exhalation, the eggs readily become spoiled, and the development 
 of the embryo is arrested. The loss of weight during natural incu- 
 bation, principally due to the exhalation of water, has been found by 
 Baudrimont and St. Ange' to be over 15 per cent, of the entire 
 weight of the egg. 
 
 Secondly, the egg absorbs oxygen and exhales carbonic acid. 
 The two observers mentioned above, ascertained that during eigh- 
 
 ' Du Developpement du Foetus. Paris, 1850, p. 143. 
 
508 AMNION AND ALLANTOIS. 
 
 teen days' incubation, the egg absorbed nearly 2 per cent, of its 
 weight of oxygen, while the quantity of carbonic acid exhaled from 
 the sixteenth to the nineteenth day of incubation amounted to no 
 less than 3 grains in the twenty-four hours.' It is curious to observe, 
 also, that in the egg during incubation, as well as in the adult 
 animal, more oxygen is absorbed than is returned by exhalation 
 under the form of carbonic acid. 
 
 It is evident, therefore, that a true respiration takes place by 
 means of the allantois, through the membranes of the shell. 
 
 The allantois, however, is not simply an organ of respiration ; it 
 takes part also in the absorption of nutritious matter. As the pro- 
 cess of development advances, the skeleton of the young chick, at 
 first entirely cartilaginous, begins to ossify. The calcareous mat- 
 ter, necessary for this ossification, is, in all probability, derived from 
 the shell. The shell is certainly lighter and more fragile toward 
 the end of incubation than at first; and, at the same time, the cal- 
 careous ingredients of the bones increase in quantity. The lime- 
 salts, requisite for the process of ossification, are apparently ab- 
 sorbed from the shell by the vessels of the allantois, and by them 
 transferred to the skeleton of the growing chick ; so that, in the 
 same proportion that the former becomes weaker, the latter grows 
 stronger. This diminution in density of the shell is connected not 
 only with the development of the skeleton, but also with the final 
 escape of the chick from the egg. This deliverance is accomplished 
 mostly by the movements of the chick itself, which become, at a 
 certain period, sufficiently vigorous to break out an opening in the 
 attenuated and weakened egg-shell. The first fracture is generally 
 accomplished by a stroke from the end of the bill ; and it is pre- 
 cisely at this point that the solidification of the skeleton is most 
 advanced. The egg-shell itself, therefore, which at first only serves 
 for the protection of the imperfectly-formed embryo, afterward 
 lurnishes the materials which are used to accomplish its own demo- 
 lition, and at the same time to effect the escape of the fully deve- 
 loped foetus. 
 
 Toward the latter periods of incubation, the allantois becomes 
 more and more adherent to the internal surface of the shell-mem- 
 brane. At last, when the chick, arrived at the full period of de- 
 velopment, escapes from its confinement, the allantoic vessels are 
 torn off at the umbilicus ; and the allantois itself, cast off as a use- 
 
 ' Op. cit., pp. 138 and 149. 
 
DEVELOPMENT OF THE CHICK. 509 
 
 less and effete organ, is left behind in the cavity of the abandoned 
 egg-shell. The allantois is, therefore, strictly speaking, a foetal 
 organ. Developed as an accessory structure from a portion of the 
 intestinal canal, it is exceedingly active and important during the 
 middle and latter periods of incubation ; but when the chick is 
 completely formed, and has become capable of carrying on an in- 
 dependent existence, both the amnion and the allantois are detached 
 and thrown off as obsolete structures, their place being afterward 
 supplied by other organs belonging to the adult condition. 
 
510 DEVELOPMENT OF THE EGG IN HUMAN SPECIES. 
 
 CHAPTER X, 
 
 DEVELOPMENT OF THE EGG IN THE HUMAN 
 SPECIES.— FORMATION OF THE CHORION. 
 
 We have already described, in a preceding chapter, the manner 
 in which the outer lamina of the amniotic fold becomes adherent 
 to the adjacent surface of the vitelline membrane, so as to form 
 with it but a single layer ; and in which these two membranes, thus 
 fused and united with each other, form at that time the single ex- 
 ternal investing membrane of the egg. The allantois, in its turn, 
 afterward comes in contact with the investing membrane, and lies 
 immediately beneath it, as a double vascular membranous sac. In 
 the egg of the human subject the development of the membranes, 
 though carried on essentially upon the same plan with that which 
 we have already described, undergoes, in addition, some further 
 modifications, which we shall now proceed to explain. 
 
 The first of these peculiarities is that the allantois, after spread- 
 ing out upon the inner surface of 
 Fig. 196. the external investing membrane, 
 
 adheres to, and fuses with it, just 
 as the outer lamina of the amni- 
 otic fold has previously fused 
 with the vitelline membrane. At 
 the same time, the two layers be- 
 longing to the allantois itself also 
 come in contact and fuse toge- 
 ther ; so that the cavity of the 
 allantois is obliterated, and instead 
 of forming a membranous sac con- 
 taining fluid, this organ is convert- 
 ed into a simple vascular membrane. 
 (Fig. 196.) This membrane, 
 moreover, being, after a time, 
 thoroughly fused and united with the two which have preceded it, 
 takes the place which was previously occupied by them. It is then 
 
 HrMAN Ovum, about the end of the first 
 month; showing formation of chorion. — 1. 
 Umbilical vesicle. 2. Amnion. 3. Chorion. 
 
FOKMATION OF THE CHORION. 511 
 
 termed the cJwrion, and thus becomes the sole external investing 
 Tnembrane of the egg. 
 
 We find, therefore, that the chorion, that is, the external coat or 
 investment of the egg, is formed successively by three distinct mem- 
 branes, as follows: first, the original vitelline membrane; secondly, 
 the outer lamina of the amniotic fold; and, thirdly, the allantois; 
 the last predominating over the two former by the rapidity of its 
 growth, and absorbing them into its substance, so that they become 
 finally completely incorporated with its texture. 
 
 It is easy to see, also, how, in consequence of the above process, 
 the body of the foetus, in the human egg, becomes inclosed in two 
 distinct membranes, viz., the amnion, which is internal and conti- 
 nuous with the foetal integument, and the chorion, which is external 
 and supplied with vessels from the cavity of the abdomen. The 
 umbilical vesicle is, of course, situated between the two ; and the rest 
 of the space between the chorion and the amnion is occupied by 
 a semi-fluid gelatinous material, somewhat similar in appearance 
 to that of the vitreous body of the eye. 
 
 The obliteration of the cavity of the allantois takes place very 
 early in the human subject, and, in fact, keeps pace almost entirely 
 with the progress of its growth ; so that this organ never presents, 
 in the human egg, the appearance of a hollow sac, filled with 
 fluid, but rather that of a flattened vascular membrane, enveloping 
 the body of the foetus, and forming the external^membrane of the 
 egg. Notwithstanding this difference, however, the chorion of the 
 human subject is, in respect to its mode of formation, the same 
 thing with the allantois of the lower animals; its chief peculiarity 
 consisting in the fact tbat its opposite surfaces are adherent to each 
 other, instead of remaining separate and inclosing a cavity filled 
 with fluid. 
 
 The next peculiarity of the human chorion is, that it becomes 
 shaggy. Even while the egg is still very small, and has but recently 
 found its way into the uterine cavity, its exterior is already seen 
 to be covered with little transparent prominences, like so many 
 villi (Fig. 196), which increase the extent of its surface, and assist 
 in the absorption of fluids from without. The villi are at this time 
 quite simple in form, and altogether homogeneous in structure. 
 
 As the egg increases in size, the villi rapidly elongate, and be- 
 come divided and ramified by the repeated budding and sprouting of 
 lateral offshoots from every part. After this process of growth has 
 gone on for some time, the external surface of the chorion presents 
 
512 DEVELOPMENT OF THE EGG IN HUMAN SPECIES. 
 
 a uniformly velvety or shaggy appearance, owing to its being co- 
 vered everywhere with these tufted and compound villosities. 
 
 The villosities themselves, when examined by the microscope, 
 have an exceedingly well marked and characteristic appearance. 
 (Fig. 197.) They originate from the surface of the chorion by a 
 
 somewhat narrow stem, and divide 
 into a multitude of secondary and 
 tertiary branches, of varying size 
 and figure; some of them slender 
 and filamentous, others club-shaped, 
 many of them irregularly swollen at 
 various points. All of them termi 
 nate by rounded extremities, giving 
 to the whole tuft a certain resem- 
 blance to some varieties of sea- weed. 
 The larger trunks and branches of 
 ,r-"''^\>\T^'"°'''/'S7/<'' '^-^^^^'"■'^^a?^ ^^® villosity are seen to contain nu- 
 ilCr^^N^^^X/^^^^ merous minute nuclei, imbedded in 
 
 a nearly homogeneous, or finely gra- 
 nular substratum. The smaller ones 
 appear, under a low magnifying 
 power, simply granular in texture. 
 
 These villi are altogether peculiar 
 in appearance, and quite unlike any 
 other structure which may be met with in the body. Wherever we 
 find, in the uterus, any portion of a membrane having villosities 
 like these, we may be sure that pregnancy has existed ; for such 
 villosities can only belong to the chorion, and the chorion itself is 
 a part of the foetus. It is developed, as we have seen, as an out- 
 growth from the intestinal canal, and can only exist, accordingly, 
 as a portion of the fecundated egg. The presence of portions of a 
 shaggy chorion is therefore as satisfactory proof of the existence 
 of pregnancy, as if we had found the body of the foetus itself. 
 
 While the villosities which we have just described are in pro- 
 cess of formation, the allantois itself has completed its growth, and 
 has become converted into a permanent chorion. The bloodvessels 
 coming from the allantoic arteries accordingly ramify over the 
 chorion, and supply it with a tolerably abundant vascular network. 
 The growth of the foetus, moreover, at this time, has reached such 
 a state of activity, that it requires to be supplied with nourishment 
 by vascular absorption, instead of the slow process of imbibition, 
 
 Compound villosity of Human Cho- 
 EION, ramified extremity. From a three 
 mouths' foetus. Magnified .'50 diameters. 
 
FORMATION OF THE CHORION. 
 
 513 
 
 Fig. 198. 
 
 Extrernily of vrLLOsiTT of 
 Chorion, more highly magni- 
 fied ; showing the ai-rangement of 
 bloodvessels in its interior. 
 
 which has heretofore taken place through the comparatively incom- 
 })lete and structureless villi of the cho- 
 rion. The capillary vessels, accordingly, 
 with which the chorion is supplied, begin 
 to penetrate into the substance of its vil- 
 losities. They enter the base or stem of 
 each villosity, and, following every divi- 
 sion of its compound ramifications, finally 
 reach its rounded extremities. Here 
 they turn upon themselves in loops (Fig. 
 198), like the vessels in the papillae of 
 the skin, and retrace their course, to unite 
 finally with the venous trunks of the 
 chorion. 
 
 The villi of the chorion are therefore 
 very analogous in structure to those of 
 the intestine; and their power of absorp- 
 tion, as in other similar instances, corresponds with the abundance 
 of their ramifications, and the extent of their vascularity. 
 
 It must be remembered, also, that these vessels all come from the 
 abdomen of the foetus ; and that whatever substances are taken up 
 by them are transported directly to the interior of the embryo, and 
 used for the nourishment of its tissues. The chorion, therefore, as 
 soon as its villi and bloodvessels are completely developed, becomes 
 an exceedingly active organ in the nutrition of the foetus; and con- 
 stitutes, in fact, the only means by which, new material can be in- 
 troduced from without. 
 
 The existence of this general vascularity of the chorion affords 
 also, as Coste was the first to point out, a striking indication 
 that this membrane is in reality identical with the allantois of the 
 lower animals. If the reader will turn back to the illustrations of 
 the formation of the amnion and allantois (Chap. IX.), he will see 
 that the first chorion or investing membrane is formed exclusively 
 by the vitelline membrane, which is never vascular and cannot be- 
 come so by itself, since it has no direct connection with the foetus. 
 The second chorion is formed by the union of the vitelline mem- 
 brane with the outer lamina of the amniotic fold. Both laminas 
 of the amniotic fold are at first vascular, since they are portions of 
 the external blastodermic layer, and derive their vessels from the 
 integument of the foetus. But after the outer lamina has become 
 completely separated from the inner, by the disappearance of the 
 33 
 
514 DEVELOPMENT OF THE EGG IN HUMAN SPECIES. 
 
 partition which for a time connected the two with each other (Fig. 
 192, c), this source of vascular supply is cut off; and the second cho- 
 rion cannot, therefore, remain vascular after that period. But the 
 third or permanent chorion, that is, the allantois, derives its ves- 
 sels directly from those of the foetus, and retains its connection with 
 them during the whole period of gestation. A chorion, therefore, 
 which is universally and permanently vascular, can be no other 
 tlian the allantois, converted into an external investing membrane 
 of the egg. 
 
 Thirdly, the chorion, which is at one time, as we have seen, every- 
 where villous and shaggy, becomes afterward partially bald. This 
 change begins to take place about the end of the second month. 
 It commences at a point opposite the situation of the foetus and the 
 insertion of the foetal vessels. The villosities in this region cease 
 growing; and as the entire egg continues to enlarge, the villosities 
 at the point indicated fail to keep pace with its growth, and with 
 the progressive expansion of the chorion. They accordingly be- 
 come at this part thinner and more scattered, leaving the surface 
 of the chorion comparatively smooth and bald. This baldness in- 
 creases in extent and becomes more and more complete, spreading 
 and advancing over the adjacent portions of the chorion, until at 
 least two-thirds of its surface have become nearly or quite destitute 
 of villosities. 
 
 .' At the opposite point of the surface of the egg, however, that 
 
 portion, namely, which corre- 
 sponds with the insertion of the 
 foetal vessels, the villosities, 
 instead of becoming atrophied, 
 continue to grow ; and this 
 portion of the chorion becomes 
 even more shaggy and thickly 
 set than before. The conse- 
 quence is that the chorion 
 afterward presents a very dif- 
 ferent appearance at different 
 portions of its surface. (Fig. 
 199.) The greater part of it is 
 
 HnMAN OvcM at end of third month; showing g^^yQ^Ji . ^ut a Certain portion, 
 placental portion of the chorion fully formed. i • 1 £• 
 
 constituting about one-third or 
 the whole, is covered with a soft and spongy mass of long, thickly- 
 set, compound villosities. It is this thickened and shaggy portion, 
 
 Fig. 199. 
 
FORMATION OF THE CHORION. 515 
 
 which is afterward concerned in the formation of the placenta : 
 while the remaining smooth portion continues to be known under 
 the name of the chorion. The placental portion of the chorion 
 becomes distinctly limited and separated from the remainder by 
 about the end of the third month. 
 
 The vascularity of the chorion keeps pace, in its different parts 
 respectively, with the atrophy and development of its villosities. 
 As the villosities shrivel and disappear over a part of its extent, 
 the looped capillary vessels, which they at first contained, disappear 
 also ; so that the smooth portion of the chorion shows afterward 
 only a few straggling vessels running over its surface, and does not 
 contain any abundant capillary plexus. In the thickened portion, 
 on the other hand, the vessels lengthen and ramify to an extent cor- 
 responding with that of the villosities in which they are situated. 
 The allantoic arteries, coming from the abdomen of the foetus, enter 
 the villi, and penetrate through their whole extent ; forming, at the 
 placental portion of the chorion, a mass of tufted and ramified vas- 
 cular loops, while over the rest of the membrane they are merely 
 distributed as a few single and scattered vessels. 
 
 The chorion, accordingly, is the external investing membrane of 
 the Qgg^ produced by the consolidation and transformation of the 
 allantois. The placenta, furthermore, so far as it has now been 
 described, is evidently a part of the chorion ; that part, namely, 
 which is thickened, shaggy and vascular, while the remainder is 
 comparatively thin, smooth, and membranous. 
 
516 DEVELOPMENT OF UTERINE MUCOUS MEMBRANE. 
 
 CHAPTER XI. 
 
 DEVELOPMENT OF UTERINE MUCOUS MEMBRANE.— 
 FORMATION OF TUE DECIDUA. 
 
 In fish, reptiles, and birds, tlae egg is either provided with a sup- 
 ply of nutritious material contained within its membranes, or it is 
 so placed, after its discharge from the body of the parent, that it 
 can absorb these materials from without. Thus, in the egg of the 
 bird, the young embryo is supported upon the albuminous matter 
 deposited around the vitellus ; while in the frog and fish, moisture, 
 oxygen, saline substances, &c., are freely imbibed from the water 
 in which the egg is placed. 
 
 But in the quadrupeds, as well as in the human species, the egg 
 is of minute size, and the quantity of nutritious matter which it 
 contains is sufficient to last only for a very short time. Moreover, 
 the development of the foetus takes place altogether within the body 
 of the female, and no supply, therefore, can be obtained directly 
 from the external media. In these instances, accordingly, the mu- 
 cous membrane of the uterus, which is found to be unusually 
 developed and increased in functional activity during the period of 
 gestation, becomes a source of nutrition for the fecundated egg. 
 The uterine mucous membrane, thus developed and hypertrophied, 
 is known by the name of the Decidua. 
 
 It has received this name because, as we shall hereafter see, it 
 becomes exfoliated and thrown off, at the same time that the egg 
 itself is finally discharged. 
 
 The mucous membrane of the body of the uterus, in the unimpreg- 
 nated condition, is quite thin and delicate, and presents a smooth 
 and slightly vascular internal surface. There is, moreover, no layer 
 of submucous cellular tissue between it and the muscular substance 
 of the uterus ; so that the mucous membrane cannot here, as in 
 most other organs, be easily dissected up and separated from the 
 subjacent parts. The structure of the mucous membrane itself, 
 however, is sufficiently well marked and readily distinguishable 
 
FORMATION OF THE DECIDUA. 
 
 517 
 
 Fig. 200. 
 
 Uterine MrroFs Membrakk, as 
 seeu in vertical section. — a. Free surface. 
 6. Attached surface. 
 
 from that of other parts. It consists, throughout, of minute tubular 
 follicles, ranged side by side, and running perpendicularly to the 
 free surface of the mucous membrane. (Fig. 200.) Near this free 
 surface, they are nearly straight ; but 
 toward the deeper surface of the mu- 
 cous membrane, where they terminate 
 in blind extremities, or cul-de-sacs, 
 they become more or less wavy or 
 spiral in their cour.se. The tubules 
 are about yig of an inch in diameter, 
 and are lined throughout with co- 
 lumnar epithelium. (Fig. 201.) They 
 occupy the entire thickness of the ute- 
 rine mucous membrane, their closed 
 extremities resting upon the subjacent 
 
 muscular tissue, while their mouths open into the cavity of the ute- 
 rus. A few fine bloodvessels penetrate the mucous membrane from 
 below, and, running upward 
 
 between the tubules, encircle Fig- 201. 
 
 their superficial extremities 
 with a capillary network. 
 There is no areolar tissue in 
 the uterine mucous mem- 
 brane, but only a small quan- 
 tity of spindle-shaped fibro- 
 plastic fibres, scattered be- 
 tween the tubules. 
 
 As the fecundated egg is 
 about to descend into the 
 cavity of the uterus, the mu- 
 cous membrane, above de- 
 scribed, takes on an increased 
 
 . . Uterixe Tubules, from mucous membrane of 
 
 activity of growth and an unimpregnated human uterus. 
 
 unusual development. It be- 
 comes tumefied and vascular; and as it increases in thickness, it 
 projects, in rounded eminences or convolutions, into the uterine 
 cavity. (Fig. 202.) In this process, the tubules of the uterus in- 
 crease in length, and also become wider; so that their open mouths 
 may be readily seen by the naked e3^e upon the uterine surface, as 
 numerous minute perforations. The bloodvessels of the mucous 
 membrane also enlarge and multiply, and inosculate freely with 
 
518 DEVELOPMENT OF UTERINE MUCOUS MEMBRANE. 
 
 each other; so that the vascular network encircling the tubules be- 
 comes more extensive and abundant. 
 
 The internal surface of the uterus, accordingly, after this process 
 has been for some time going on, presents a thick, rich, soft, vas- 
 cular, and velvety lining, quite different from that which is to be 
 found in the unimpregnated condition. In consequence of this 
 difference, the lining membrane of the uterus, in the impregnated 
 condition, was formerly supposed to be an entirely new product, 
 thrown out by exudation from the uterine surface, and analogous, 
 in this respect, to the inflammatory exudations of croup and pleu- 
 risy. It is now known, however, to be no other than the mucous 
 membrane of the uterus itself, thickened and hypertrophied to an 
 extraordinary degree, but still retaining all its natural connections 
 and its original anatomical structure. 
 
 The hypertrophied mucous membrane, above described, consti- 
 tutes the Decidua vera. Its formation is confined altogether to the 
 body of the uterus, the mucous membrane of the cervix taking no 
 part in the process, but retaining its original appearance. The 
 decidua vera, therefore, commences above, at the orifices of the 
 Fallopian tubes, and ceases below, at the situation of the os inter- 
 num. The cavity of the cervix, at this time, begins to be filled 
 with an abundant secretion of its peculiarly viscid mucus, which 
 blocks up, more or less completely, its passage, and protects the 
 internal cavity. But there is no membranous partition at this time 
 covering the os internum, and the mucous membranes of the cervix 
 and of the body of the uterus, though very different in appearance, 
 are still perfectly continuous with each other. When we cut open 
 the cavity of the uterus, therefore, in this condition, we find its 
 internal surface lined with the decidua vera, with the opening of 
 the OS internum below and the orifices of the Fallopian tubes above, 
 perfectly distinct, and in their natural positions. (Fig. 202.) 
 
 As the fecundated egg^ in its journey from above downward, 
 passes the lower orifice of the Fallopian tube, it insinuates itself 
 between the opposite surfaces of the uterine mucous membrane, 
 and becomes soon afterward lodged in one of the furrows or de- 
 pressions between the projecting convolutions of the decidua. 
 (Fig. 202.) It is at this situation that an adhesion is subsequently 
 to take place between the external membranes of the egg, on the 
 one hand, and the uterine decidua on the other. Now at the point 
 where the egg becomes fixed and entangled, as above stated, a still 
 more rapid development than before takes place in the uterine 
 
FORMATION OF THE DECIDUA. 
 
 51^ 
 
 mucous membrane. Its projecting folds begin to grow up around 
 the egg in such a manner as to partially inclose it in a kind of 
 circumvallation of the decidua, and to shut it off", more or less com- 
 
 Fiff. 202. 
 
 Fig. 203. 
 
 Impreuxatep Uterus; showing 
 formation of decidua. The decidua is 
 represented in black ; and the egg is 
 !*een, at the fundus of the uterus, engaged 
 between two of its projecting convolu- 
 tions. 
 
 Impregnated Uterus, with pro- 
 jecting folds of decidua growing up 
 around the egg. The narrow opening, 
 where the edges of the folds approach 
 each other, is seen over the most promi- 
 nent portion of the egg. 
 
 Fi?. 204. 
 
 pletely, from the general cavity of the uterus. (Fig. 203.) The 
 egg is thus soon contained in a special cavity of its own, which 
 still communicates for a time with the general cavity of the uterus 
 by a small opening, situated over its most prominent portion, which 
 is known as the "decidual umbilicus." As the above process of 
 growth goes on, this opening becomes narrower and narrower, while 
 the projecting folds of decidua approach each other over the sur- 
 face of the egg. At last these folds actually touch each other and 
 unite, forming a kind of cicatrix which 
 remains for a certain time, to mark the 
 situation of the original opening. 
 
 When the development of the uterus and 
 its contents has reached this point (Fig. 
 204), it will be seen that the egg is com- 
 pletely inclosed in a distinct cavity of its 
 own ; being everywhere covered with a 
 decidual layer of new formation, which 
 has thus gradually enveloped it, and by 
 which it is concealed from view when the 
 uterine cavity is laid open. This newly 
 formed layer of decidua, enveloping, as 
 
 , 1-111 • • • n showing egg completely inclosed 
 
 above aescribea, the projecting portion oi by decidua reflexa. 
 
 Impregnated Uterus; — 
 
520 DEVELOPMENT OF UTERINE MUCOUS MEMBRANE. 
 
 the egg, is called the Decidua refiexa ; because it is reflected over 
 the egg, by a continuous growth from the general surface of the 
 uterine mucous membrane. The orifices of the uterine tubules, ac- 
 cordingly, in consequence of the manner in which the decidua 
 reflexa is formed, will be seen not only on its external surface, or 
 that which looks toward the cavity of the uterus, but .also on its 
 internal surface, or that which looks toward the egg. 
 
 The decidua vera, therefore, is the original mucous membrane 
 lining the surface of the uterus; while the decidua reflexa is a new 
 formation, which has grown up round the egg and inclosed it in a 
 distinct cavity. 
 
 If abortion occur at this time, the mucous membrane of the 
 uterus, that is, the decidua vera, is thrown off", and of course brings 
 away with it the egg and decidua reflexa. On examining the mass 
 discharged in such an abortion, the egg will accordingly be found 
 imbedded in the substance of the decidual membrane. One side 
 of this membrane, where it has been torn away from its attachment 
 to the uterine walls, is ragged and shaggy; the other side, corres- 
 ponding to the cavity of the uterus, is smooth or gently convoluted, 
 and presents very distinctly the orifices of the uterine tubules; 
 while the egg itself can only be extracted by cutting through the 
 decidual membrane, either from one side or the other, and opening 
 in this way the special cavity in which it has been inclosed. 
 
 During the formation of the decidua reflexa, the entire egg, as 
 well as the body of the uterus which contains it, has considerably 
 enlarged. That portion of the uterine mucous membrane situated 
 immediately underneath the egg, and to which the egg first became 
 attached, has also continued to increase in thickness and vascu- 
 larity. The remainder of the decidua vera, however, ceases to 
 grow as rapidly as before, and no longer keeps pace with the in- 
 creasing size of the egg and of the uterus. It is still very thick and 
 vascular at the end of the third month ; but after that period it 
 becomes comparatively thinner and less glandular in appearance, 
 while the unusual activity of growth and development is concen- 
 trated in the egg, and in that portion of the uterine mucous mem- 
 brane which is in immediate contact with it. 
 
 Let us now see in what manner the egg becomes attached to the 
 decidual membrane, so as to derive from it the requisite supply of 
 nutritious material. It must be recollected that, while the above 
 changes have been taking place in the walls of the uterus, the for- 
 mation of the embryo in the egg, and the development of the 
 
FORMATION OF THE DECIDUA. 
 
 521 
 
 Fiff. 205. 
 
 amnion and chorion have been going on sinnultaneously. Soon 
 after the entrance of the egg into the uterine cavity, its external 
 investing membrane becomes covered with projecting filaments, or 
 villosities, as previously described, (Chap. X.) These villosities, 
 which are at first, as we have seen, solid and non-vascular, insinuate 
 themselves, as they grow, into the uterine tubules, or between the 
 folds of the decidual surface with which the egg is in contact, pene- 
 trating in this way into little cavities or follicles of the uterine 
 mucous membrane, formed either from the cavities of the tubules 
 themselves, or by the adjacent surfaces (>f minute projecting folds. 
 When the formation of the decidua reflexa is accomplished, the 
 chorion has already become uniformly 
 shaggy; and its villosities, spreading in all 
 directions from its external surface, pene- 
 trate everywhere into the follicles above de- 
 scribed, both of the decidua vera underneath 
 it, and the contiguous surface of the decidua 
 reflexa with which it is covered. (Fig. 206.) 
 In this way the egg becomes entangled 
 with the decidua, and cannot then be rea- 
 dily separated from it, without rupturing 
 some of the filaments which have grown 
 from its surface, and have been received 
 into the cavity of the follicles. The nu- 
 tritious fluids, exuded from the soft and 
 glandular textures of the decidua, are now 
 readily imbibed by the villosities of the chorion; and a more rapid 
 supply of nourishment is thus provided, corresponding in abun- 
 dance with the increased and increasing size of the egg. 
 
 Very soon, however, a still greater activity of absorption be- 
 comes necessary ; and, as we have seen in a preceding chapter, the 
 external membrane of the egg becomes vascular by the formation 
 of the allantoic bloodvessels, which emerge from the body of the 
 foetus, to ramify in the chorion, and penetrate everywhere into the 
 villosities with which it is covered. Each villosity, then, as it lies 
 imbedded in its uterine follicle, contains a vascular loop through 
 which the foetal blood circulates, increasing the rapidity with which 
 absorption and exhalation take place. 
 
 Subsequently, furthermore, these vascular tufts, which are at first 
 uniformly abundant throughout the whole extent of the chorion, 
 disappear over a portion of its surface, while they at the same time 
 
 Imprrgnatf, I) Uterus; 
 showiug coiiuection between vil- 
 losities of chorion and decidual 
 membranes. 
 
522 DEVELOPMENT OF UTERINE MUCOUS MEMBRANE. 
 
 Fig. 206. 
 
 become concentrated and still further developed at a particular 
 spot, the situation of the future placenta. (Fig. 206.) This is the 
 
 spot at which the egg is in contact with 
 the decidua vera. Here, therefore, both 
 the decidual membrane and the tufts 
 of the chorion continue to increase in 
 thickness and vascularity; while else- 
 where, over the prominent portion of 
 the egg, the chorion not only becomes 
 bare of villosities, and comparatively 
 destitute of vessels, but the decidua re- 
 flexa, which is in contact with it, also 
 loses its activity of growth, and be- 
 comes expanded into a thin layer nearly 
 destitute of vessels, and without any 
 remaining trace of tubules or follicles. 
 The uterine mucous membrane is 
 therefore developed, during the process 
 of gestation, in such a way as to provide 
 for the nourishment of the foetus in the different stages of its growth. 
 At first, the whole of it is uniformly increased in thickness (decidua 
 vera). Next, a portion of it grows upward around the egg, and 
 " covers its projecting surface (decidua reflexa). Afterward, both the 
 decidua reflexa and the greater part of the decidua vera diminish 
 in the activity of their growth, and lose their importance as a means 
 , of nourishment for the egg; while that part which is in contact with 
 the vascular tufts of the chorion continues to grow, becoming ex- 
 ceedingly developed, and taking an active part in the formation of 
 the placenta. 
 
 In the following chapter, we shall examine more particularly the 
 structure and development of the placenta itself, and of those parts 
 which are immediately connected with it. 
 
 Pre.jnaxt Utercs; showing 
 formation of placenta, by the united 
 development of a portion of the de- 
 cidna and the villosities of the cho- 
 
THE PLACENTA. 523 
 
 CHAPTER XII. 
 
 THE PLACENTA. 
 
 We have shown in the preceding chapters that the foetus, during 
 its development, depends for its supply of nutriment upon the lining 
 membrane of the maternal uterus; and that the nutriment, so sup- 
 plied, is absorbed by the bloodvessels of the chorion, and transported 
 in this way into the circulation of the foetus. In all instances, ac- 
 cordingly, in which the development of the foetus takes place within 
 the body of the parent, it is provided for by the relation thus esta- 
 blished between two sets of membranes; namely, the maternal 
 membranes which supply nourishment, and the foetal membranes 
 which absorb it. 
 
 In some species of animals, the connection between the maternal 
 and foetal membranes is exceedingly simple. In the pig, for ex- 
 ample, the uterine mucous membrane is everywhere uniformly 
 vascular; its only peculiarity consisting in the presence of nume- 
 rous transverse folds, which project from its surface, analogous to 
 the valvulse conniventes of the small intestine. The external in- 
 vesting membrane of the egg, which is the allantois, is also smooth 
 and uniformly vascular like the other. No special development of 
 tissue or of vessels occurs at any part of these membranes, and 
 no direct adhesion takes place between them ; but the vascular 
 allantois or chorion of the foetus is everywhere closely applied to 
 the vascular mucous membrane of the maternal uterus, each of the 
 two contiguous surfaces following the undulations presented by the 
 other. (Fig. 207.) By this arrangement, transudation and absorp- 
 tion take place from the bloodvessels of the mother to those of the 
 foetus, in sufficient quantity to provide for the nutrition of the latter. 
 When parturition takes place, accordingly, in these animals, a very 
 moderate contraction of the uterus is sufficient to expel its contents. 
 The egg, displaced from its original position, slides easily forward 
 over the surface of the uterine mucous membrane, and is at last 
 discharged without any hemorrhage or laceration of connecting 
 
524 
 
 THE PLACENTA. 
 
 parts. In other instances, however, the development of the foetus 
 requires a more elaborate arrangement of the vascular membranes. 
 
 Fi!?. 207. 
 
 FcETAL I'ifi, with its membranes, contaiiir-d in cavity of uterus.- 
 c, c. Cavity uf uterus, d. Amnion, e, e. Allantoi.s. 
 
 I, a, 6, 6. Walls of uterus. 
 
 In the cow, for example, the external membrane of the Q^g^ beside 
 being everywhere supplied with branching vessels, presents upon 
 various points of its surface no less than from seventy to eighty oval 
 spots, at each of which the vessels of the chorion are developed into 
 abundant tufted prominences, hanging from its exterior as a thick, 
 velvety, vascular mass. At each point of the uterine mucous mem- 
 brane, corresponding with one of these tufted masses, the maternal 
 bloodvessels are developed in a similar manner, projecting into the 
 uterine cavity as a flattened rounded mass or cake; which, with that 
 part of the foetal chorion which is adherent to it, is known by the 
 
 Cotyledon op Cow's Uterus.— a, a. Surface of fretai chorion 6, 6. Bloodve'ssels of fcetal 
 chorion, d, d. Bloodvessels of uterine mucous membrane, c, c. Surface of uterine mucous mem- 
 braue. 
 
 name of the Cotyledon. Each cotyledon forms, therefore, a little 
 placenta. (Fig. 208.) In its substance the tufted vascular loops 
 
THE PLACENTA. 525 
 
 coming from the uterine mucous membrane {d, d) are entangled 
 with those coming from the membranes of the foetus {b, b). There 
 is no absolute adhesion between the two sets of vessels, but only 
 an interlacement of their ramified extremities; and with a little 
 care in manipulation the foetal portion of the cotyledon may be 
 extricated from the maternal portion, without lacerating either. In 
 consequence, however, of this intricate interlacement of the vessels, 
 transudation of fluids will evidently take place with great readiness, 
 from one system to the other. 
 
 The form of placenta, therefore, met with in these animals, is one 
 in which the bloodvessels of the foetal chorion are simply entangled 
 with those of the uterine mucous membrane. In the human sub- 
 ject, the structure of the placenta is a little more complicated, though 
 the main principles of its formation are the same as in the above 
 instances. 
 
 From what has already been said in the foregoing chapters, it 
 appears that in the human subject, as well as in the lower animals, 
 the placenta is formed partly by the vascular tufts of the chorion, 
 and partly by the thickened mucous membrane of the uterus in 
 which they are entangled. During the third month, those portions 
 of the chorion and decidua which are destined to undergo this 
 transformation become more or less distinctly limited in their form 
 and dimensions ; and a thickened vascular mass, partly maternal 
 and partly foetal in its origin, shows itself at the spot where the 
 placenta is afterward to be developed. This mass is constituted in 
 the following manner. 
 
 It will be recollected that the villi of the chorion, when first 
 formed, penetrate into follicles situated in the substance of the 
 uterine mucous membrane; and that after they have become vas- 
 cular, they elongate rapidly and are developed into tufted ramifi- 
 cations of bloodvessels, each one of which turns upon itself in a 
 loop at the end of the villus. At the same time the uterine follicle, 
 into which the villus has penetrated, enlarges to a similar extent ; 
 sending out branching diverticula, corresponding with the mutiplied 
 ramifications of the villus. In fact, the growth of the follicle and 
 that of the villus go on simultaneously and keep pace with each 
 other ; the latter constantly advancing as the cavity of the former 
 enlarges. 
 
 But it is not only the uterine follicles which increase in size and 
 in complication of structure at this period. The capillary blood- 
 vessels, which lie between them and ramify over their exterior, 
 
52Q THE PLACENTA. 
 
 also become unusually developed. They enlarge and inosculate 
 freely with each other; so that every uterine follicle is soon covered 
 with an abundant network of dilated capillaries, derived from the 
 bloodvessels of the original decidua. At this time, therefore, each 
 vascular loop of the foetal chorion is covered, first, with a layer 
 forming the wall of the villus. This is in contact with the lining 
 membrane of a uterine follicle, and outside of this again are the 
 capillary vessels of the uterine mucous membrane ; so that two 
 distinct membranes intervene between the walls of the foetal capil- 
 laries on the one hand and those of the maternal capillaries on the 
 other, and all transudation must take place through the substance 
 of these two membranes. 
 
 As the formation of the placenta goes on, the anatomical arrange- 
 ment of the foetal vessels remains the same. They continue to 
 form vascular loops, penetrating deeply into the decidual mem- 
 brane; only they become constantly more elongated, and their 
 ramifications more abundant and tortuous. The maternal capilla- 
 ries, however, situated on the outside of the uterine follicles, become 
 considerably altered in their anatomical relations. They enlarge 
 excessively; and, by encroaching constantly upon the little islets 
 or spaces between them, fuse successively with each other; and, 
 losing gradually in this way the characters of a capillary network, 
 become dilated into wide sinuses, which communicate freely with 
 the enlarged vessels in the muscular walls of the uterus. As the 
 original capillary plexus occupied the entire thickness of the hyper- 
 trophied decidua, the vascular sinuses, into which it is thus con- 
 verted, are equally extensive. They commence at the inferior 
 surface of the placenta, where it is in contact with the muscular 
 walls of the uterus, and extend through its whole thickness, quite 
 up to the surface of the foetal chorion. 
 
 As the maternal sinuses grow upward, the vascular tufts of the 
 chorion grow downward, and extend also through the entire thick- 
 ness of the placenta. At this period, the development of the 
 bloodvessels, both in the foetal and maternal portions of the placenta, 
 is so excessive that all the other tissues, which originally co-ex- 
 isted with them, become retrograde and disappear almost altogether. 
 If a villus from the foetal portion of the placenta be examined at this 
 time by transparency, in the fresh condition, it will be seen that its 
 bloodvessels are covered only with a layer of homogeneous, or finely 
 granular material, -ggV^ of an inch in thickness, in which are im- 
 bedded small oval-shaped nuclei, similar to those seen at an earlier 
 
THE PLACENTA. 
 
 527 
 
 Fig. 209. 
 
 period in the villosities of the chorion. The villosities of the cho- 
 rion are now, therefore, hardly anything more than ramified and tor- 
 tuous vascular loops; the remaining sub- 
 stance of the villi having been atrophied 
 and absorbed in the excessive growth of 
 the bloodvessels. (Fig. 209.) The uterine 
 follicles have at the same time lost all trace 
 of their original structure, and have be- 
 come mere vascular sinuses, into which 
 the tufted foetal bloodvessels are received, 
 as the villosities of the chorion were at 
 first received into the uterine follicles. 
 
 Finally, the walls of the foetal blood- 
 vessels having come into close contact 
 with the walls of the maternal sinuses, 
 the two become adherent and fuse toge- 
 ther ; so that a time at last arrives, when 
 we can no longer separate the foetal ves- 
 sels, in the substance of the placenta, from the maternal sinuses 
 without lacerating either the one or the other, owing to the second- 
 ary adhesion which has taken place between them. 
 
 The placenta, therefore, when perfectly formed, has the structure 
 which is shown in the accompanying diagram (Fig. 2i0), repre- 
 
 Extreraity of Foetal Tuft 
 of humaa placenta; from an in- 
 jected specimen. Magnified 40 
 diameters. 
 
 Fiff. 210. 
 
 Vertical section of Placenta, showing arrangement of maternal and fcetal vess 
 rion. 6, 6. Decidua. c, c, c, c. Orifices of uterine sinuses. 
 
528 THE PLACENTA. 
 
 senting a vertical section of the organ through its entire thickness. 
 At a, a, is seen the chorion, receiving the umbilical vessels from the 
 body of the foetus through the umbilical cord, and sending out its 
 compound and ramified vascular tufts into the substance of the pla- 
 centa. At b b, is the attached surface of the decidua, or uterine 
 mucous membrane ; and at c, c, c, c, are the orifices of uterine ves- 
 sels which penetrate it from below. These vessels enter the placenta 
 in an extremely oblique direction, though they are represented in 
 the diagram, for the sake of distinctness, as nearly perpendicular. 
 When they have once penetrated, however, the lower portion of 
 the decidua, they immediately dilate into the placental sinuses 
 (represented, in the diagram, in black), which extend through the 
 whole thickness of the organ, closely embracing all the ramifica- 
 tions of the foetal tufts. It will be seen, therefore, that the placenta, 
 arrived at this stage of completion, is composed essentially of 
 nothing but bloodvessels. No other tissues enter into its structure, 
 for all those which it originally contained have disappeared, ex- 
 cepting the bloodvessels of the foetus, entangled with and adherent 
 to the bloodvessels of the mother. 
 
 There is, however, no direct communication between the foetal 
 and maternal vessels. The blood of the foetus is always separated 
 from the blood of the mother by a membrane which has resulted 
 from the successive union and fusion of four different membranes, 
 viz,, first, the membrane of the foetal villus ; secondly, that of the 
 uterine follicle; thirdly, the wall of the foetal bloodvessel; and, 
 fourthly, the wall of the uterine sinus. The single membrane, how- 
 ever, into which these four finally coalesce, is extremely thin, as 
 we have seen, and of enormous extent, owing to the extremely 
 abundant branching and subdivision of the foetal tufts. These tufts, 
 accordingly, in which the blood of the foetus circulates, are bathed 
 everywhere, in the placental sinuses, with the blood of the mo- 
 ther ; and the processes of endosmosis and exosmosis, of exhala- 
 tion and absorption, go on between the two with the greatest pos- 
 sible activity. 
 
 It is very easy to demonstrate the arrangement of the foetal 
 tufts in the human placenta. They can be readily seen by the 
 naked eye, and may be easily traced from their attachment at the 
 under surface of the chorion to their termination near the uterine 
 surface of the placenta. The anatomical disposition of the pla- 
 cental sinuses, however, is much more difficult of examination. 
 During life, and while the placenta is still attached to the uterus, 
 
THE PLACENTA. 529 
 
 they are filled, of course, with the blood of the mother and occupy 
 fully one-half the entire mass of the placenta. But when the pla- 
 centa is detached, the maternal vessels belonging to it are torn off' 
 at their necks (Fig. 210, c, c, c, c), and the sinuses, being then 
 emptied of blood by the compression to which the placenta is sub- 
 jected, are apparently obliterated ; and the foetal tufts, falling to- 
 gether and lying in contact with each other, appear to constitute 
 the whole of the placental mass. The existence of the placental 
 sinuses, however, and their true extent, may be satisfactorily de- 
 monstrated in the following manner. 
 
 If we take the uterus of a woman who has died undelivered at 
 the full term or thereabout, and open it in such a way as to avoid 
 wounding the placenta, this organ will be seen remaining attached 
 to the uterine surface, with all its vascular connections complete. 
 Let the foetus now be removed by dividing the umbilical cord, and 
 the uterus, with the placenta attached, placed under water, with its 
 internal surface uppermost. If the end of a blowpipe be now 
 introduced into one of the divided vessels of the uterine walls, 
 and air forced in by gentle insufflation, we can easily inflate, first, 
 the venous sinuses of the uterus itself, and next, the deeper por- 
 tions of the placenta; and lastly, the bubbles of air insinuate them- 
 selves everywhere between the foetal tufts, and appear in the most 
 superficial portions of the placenta, immediately underneath the 
 transparent chorion (a a, Fig. 210); thus showing that the placental 
 sinuses, which freely communicate with the uterine vessels, really 
 occupy the entire thickness of the placenta, and are equally ex- 
 tensive with the tufts of the chorion. We have verified this fact 
 in the above manner, on four different occasions, and in the pre- 
 sence of Prof. C. E. Gilman, Dr. Geo. T. Elliot, Dr. Henry B. Sands, 
 Dr. T. G. Thomas, Dr. T. C. Finnell, and various other medical 
 gentlemen of New York. 
 
 If the placenta be now detached and examined separately, it will 
 be found to present upon its uterine surface a number of openings 
 which are extremely oblique in their position, and which are 
 accordingly bounded on one side by a very thin, projecting, cres- 
 centic edge. These are the orifices of the uterine vessels, passing 
 into the placenta and torn off" at their necks, as above described ; 
 and by carefully following them with the probe and scissors, they 
 are found to lead at once into extensive empty cavities (the pla 
 cental sinuses), situated between the foetal tufts. We have already 
 shown that these cavities are filled during life with the maternal 
 34 
 
530 THE PLACENTA. 
 
 blood ; and there is every reason to believe that before delivery, 
 and while the circulation is going on, the placenta is at least twice 
 as large as after it has been detached and expelled from the uterus. 
 
 The placenta, accordingly, is a double organ, formed partly by 
 the chorion and partly by the decidua ; and consisting of maternal 
 and foetal bloodvessels, inextricably entangled and united with each 
 other. 
 
 The part which this organ takes in the development of the foetus 
 is an exceedingly important one. From the date of its formation, 
 at about the beginning of the fourth month, it constitutes the only 
 channel through which nourishment is conveyed from the mother 
 to the foetus. The nutritious materials, which circulate in abun- 
 dance in the blood of the maternal sinuses, pass through the inter- 
 vening membrane by endosmosis, and enter the blood of the foetus. 
 The healthy or injurious regimen, to which the mother is subjected, 
 will accordingly exert an almost immediate influence upon the 
 child. Even medicinal substances, taken by the mother and ab- 
 sorbed into her circulation, may readily transude through the pla- 
 cental vessels ; and they have been known in this way to exert a 
 Sj^ecific effect upon the foetal organization. 
 
 The placenta is, furthermore, an organ of exhalation as well as 
 of absorption. The excrementitious substances, produced in the 
 circulation of the foetus, are undoubtedly in great measure disposed 
 of by transudation through the walls of the placental vessels, to be 
 afterward discharged by the excretory organs of the mother. The 
 system of the mother may therefore be affected in this manner by 
 influences derived from the foetus. It has been remarked more 
 than once, in the lower animals, that when the female has two suc- 
 cessive litters of young by different males, the young of the second 
 litter will sometimes bear marks resembling those of the first male. 
 In these instances, the peculiar influence which produces the ex- 
 ternal mark must have been transmitted by the first male directly 
 to the foetus, from the foetus to the mother, and from the mother to 
 the foetus of the second litter. 
 
 It is also through the placental circulation that those disturbing 
 effects are produced upon the nutrition of the foetus, which result 
 from sudden shocks or injuries inflicted upon the mother. There is 
 now little room for doubt that various deformities and deficiencies of 
 the foetus, conformably to the popular belief, do really originate, in 
 certain cases, from nervous impressions, such a^ disgust, fear or anger, 
 experienced by the mother. The mode in which these effects may 
 
TFIE PLACENTA. 531 
 
 be produced is readily understood from what has been said above of 
 the anatomy and functions of the placenta. We know very well 
 how easily nervous impressions will disturb the circulation in the 
 brain, the face, the lungs, &;c, ; and the uterine circulation is quite 
 as readily influenced by similar causes, as physicians see everyday 
 in cases of amenorrhoea, menorrhagia, &c. If a nervous shock may 
 excite premature contraction in the muscular fibres of the pregnant 
 uterus and produce abortion, as not unfrequently happens, it is cer- 
 tainly capable of disturbing the course of the circulation through 
 the same organ. But the foetal circulation is dependent, to a great 
 extent, on the maternal. Since the two sets of vessels are so closely 
 entwined in the placenta, and since the foetal blood has here much 
 the same relation to the maternal, that the blood in the pulmonary 
 capillaries has to the air in the air-vesicles, it will be liable to de 
 rangement from similar causes. If the circulation of air through 
 the pulmonary tubes and vesicles be suspended, that of the blood 
 through the capillaries comes to an end also. In the same way, 
 whatever disturbs or arrests the circulation through the vessels of 
 the maternal uterus must necessarily be liable to interfere with that 
 in the foetal capillaries forming part of the placenta. And lastly, as 
 the nutrition of the foetus is provided for wholly by the placenta, it 
 will of course suffer immediately from any such disturbance of the 
 placental circulation. These effects may be manifested either in the 
 general atrophy and death of the foetus ; or, if the disturbing cause 
 be slight, in the atrophy or imperfect development of particular 
 parts; just as, in the adult, a morbid cause operating through the 
 entire system, may be first or even exclusively manifested in some 
 particular organ, which is more sensitive to its influence than other 
 parts. 
 
 The placenta must accordingly be regarded as an organ which 
 performs, during intra-uterine life, offices similar to those of the 
 lungs and the intestine after birth. It absorbs nourishment, reno- 
 vates the blood, and discharges by exhalation various excrementi- 
 tious matters, which originate in the processes of foetal nutrition. 
 
532 
 
 DISCHARGE OF THE OVUM. 
 
 CHAPTER XIII. 
 
 DISCHAKGE OF THE OVUM, AND RETROGRADE 
 DEVELOPMENT (INVOLUTION) OF THE UTERUS. 
 
 During the growth of the ovum and the formation of the pla- 
 cental structures, the muscular substance of the uterus also in- 
 creases in thickness, while the whole organ enlarges, in order to 
 accommodate the growing foetus and its appendages. The relative 
 positions of the amnion and chorion, furthermore, undergo a change 
 during the latter periods of gestation, and the umbilical cord be- 
 comes developed, at the same time, in the following manner. 
 
 In the earlier periods of foetal life the umbilical cord consists 
 simply of that portion of the allantois lying next the abdomen. It 
 is then very short, and contains the umbilical vessels running in a 
 nearly straight course, and parallel with each other, from the abdo- 
 men of the foetus to the external portions of the chorion. At this 
 time the amnion closely invests the body of the foetus, so that 
 
 the size of its cavity is but little 
 Fis- 211. larger than that of the foetus. (Fig. 
 
 211.) The space between the 
 amnion and the chorion is then 
 occupied by an amorphous gela- 
 tinous material, in which lies im- 
 bedded the umbilical vesicle. 
 
 Afterward, however, the am- 
 nion enlarges faster than the cho- 
 rion, and encroaches upon the 
 layer of gelatinous matter situated 
 between the two (Fig. 212), at 
 the same time that an albuminous 
 fluid, the "amniotic fluid," is ex- 
 uded into its cavity, in constantly 
 increasing quantity. Subsequently, the gelatinous layer, above de- 
 scribed, altogether disappears, and the amnion, at about the begin- 
 
 HcMAX Ovum about the end of the first 
 month. — 1. Umbilical vesicle. 2. Amnion. 3. 
 Choiiuu. 
 
ENLARGEMENT OF THE AMNION, 
 
 533 
 
 Human Ovum at end of third month; showing 
 enlargement of amnion. 
 
 ning of the fifth month, comes in contact with the internal surface 
 
 of the chorion. Finally, toward the end of gestation, the contact 
 
 becomes so close between these 
 
 two membranes that they are ^'?- ■^^^• 
 
 partially adherent to each 
 
 other, and it requires a little 
 
 care to separate them without 
 
 laceration. 
 
 The quantity of the amniotic 
 fluid continues to increase dur- 
 ing the latter periods of gesta- 
 tion in order to accommodate 
 the movements of the foetus. 
 These movements begin to be 
 perceptible about the fifth 
 month, at which time the 
 muscular system has already 
 attained a considerable degree of development, but become after- 
 ward more frequent and more strongly pronounced. The space 
 and freedom requisite for these movements are provided for by the 
 fluid accumulated in the cavity of the amnion. 
 
 The umbilical cord elongates, at the same time, in proportion to 
 the increasing size of the amniotic cavity. During its growth, it 
 becomes spirally twisted from right to left, the two umbilical arte- 
 ries winding round the vein in the same direction. The gelatinous 
 matter, already described as existing between the amnion and 
 chorion, while it disappears elsewhere, accumulates in the cord in 
 considerable quantity, covering the vessels with a thick, elastic en- 
 velope, which protects them from injury and prevents their being 
 accidentally compressed or obliterated. The whole is covered by a 
 portion of the amnion, which is connected at one extremity with the 
 integument of the abdomen, and invests the whole of the cord with 
 a continuous sheath, like the finger of a glove. (Fig. 213,) 
 
 The cord also contains, for a certain period, the pedicle or stem 
 of the umbilical vesicle. The situation of this vesicle, it will be 
 recollected, is always between the chorion and the amnion. Its 
 pedicle gradually elongates with the growth of the umbilical cord; 
 and the vesicle itself, which generally disappears soon after the 
 third month, sometimes remains as late as the fifth, sixth, or seventh. 
 According to Prof. Mayer, of Bonn, it may even be found, by care- 
 ful search, at the termination of pregnancy. When discovered in 
 
584 DISCHARGE OF THE OVUM. 
 
 the middle and latter periods of gestation, it presents itself as a 
 small, flattened, and shrivelled vesicle, situated underneath the 
 amnion, at a variable distance from the insertion of the umbilical 
 cord. A minute bloodvessel is often seen running to it from the 
 cord, and ramifying upon its surface. 
 
 Fig. 213. 
 
 Gravid Human Utekus and Contents, showing the relations of the cord, placenta, mem- 
 branes, &c., about the end of the seventh month. — 1. Decidua vera. 2. Decidua reflexa. .S. Chorion. 
 4. Amnion. 
 
 The decidua reflexa, during the liitter months of pregnancy, is 
 constantly distended and pushed back by the increasing size of the 
 egg; so that it is finally pressed closely against the opposite surface 
 of the decidua vera, which still lines the greater part of the uterine 
 cavity. By the end of the seventh month, the opposite surfaces 
 of the decidua vera and reflexa are in complete contact with each 
 other, though still distinct and capable of being separated without 
 difficulty. After that time, they fuse together and become con- 
 founded with each other ; the two at last forming only a single, 
 thin, friable, semi-opaque layer, in which no trace of their original 
 oflandular structure can be discovered. 
 
 This is the condition of things at the termination of pregnancy. 
 Then, the time having arrived for parturition to take place, the 
 hypertrophied muscular walls of the uterus contract forcibly upon 
 its contents, and the egg is discharged, together with the whole of 
 the decidual uterine mucous membrane. 
 
 In the human subject, as well as in most quadrupeds, the mem- 
 
SEPARATION OF THE PLACENTA. 635 
 
 branes of the egg are usually ruptured during the process of par- 
 turition; and the foetus escapes first, the placenta and the rest of 
 the appendages following a few moments afterward. Occasionally, 
 however, even in the human subject, the egg is discharged entire, 
 and the foetus liberated afterward by the laceration of the mem- 
 branes. In each case, however, the mode of separation and expul- 
 sion is, in all important particulars, the same. 
 
 The process of parturition, therefore, consists essentially in a 
 separation of the decidual membrane, which, on being discharged, 
 brings away the ovum with it. The greater part of the decidua 
 vera, having fallen into a state of atrophy during the latter months 
 of pregnancy, is by this time nearly destitute of vessels, and sepa- 
 rates, accordingly, without any perceptible hemorrhage. That por- 
 tion, however, which enters into the formation of the placenta, is, 
 on the contrary, excessively vascular; and when the placenta is 
 separated, and its maternal vessels torn off at their necks, as before 
 mentioned, a gush of blood takes place, which accompanies or 
 immediately follows the birth of the foetus. This hemorrhage, 
 which occurs as a natural phenomenon at the time of parturition, 
 does not come from the uterine vessels proper. It consists of the 
 blood which was contained in the placental sinuses, and which is 
 expelled from them owing to the compression of the placenta by 
 the walls of the uterus. Since the whole amount of blood thus 
 lost was previously employed in the placental circulation, and since 
 the placenta itself is thrown off at the same time, no unpleasant 
 effect is produced upon the mother by such a hemorrhage, because 
 the natural proportion of blood in the rest of the maternal system 
 remains the same. Uterine hemorrhage at the time of parturition, 
 therefore, becomes injurious only when it continues after complete 
 separation of the placenta ; in which case it is supplied by the 
 mouths of the uterine vessels themselves, left open by failure of the 
 uterine contractions. These vessels are usually instantly closed, 
 after separation of the placenta, by the contraction of the muscular 
 fibres of the uterus. They pass, as we have already mentioned, in 
 a,n exceedingly oblique direction, from the uterine surface to the 
 placenta ; and the muscular fibres, which cross them transversely 
 above and below, necessarily constrict them, and effectually close 
 their orifices, immediately on being thrown into a state of contraction. 
 
 Another very remarkable phenomenon, connected with preg- 
 nancy and parturition, is the appearance in the uterus of a new 
 mucous membrane, growing underneath the old, and ready to 
 take the place of the latter after its discharge. 
 
536 DISCHARGE OF THE OVUM. 
 
 If the internal surface of the body of the uterus be examined 
 immediately after parturition, it will be seen that at the spot where 
 the placenta was attached every trace of mucous membrane has 
 disappeared. The muscular fibres of the uterus are here perfectly 
 exposed and bare; while the mouths of the ruptured uterine sinuses 
 are also visible, with their thin, ragged edges hanging into the 
 cavity of the uterus, and their orifices plugged with more or less 
 abundant bloody coagula. 
 
 Over the rest of the uterine surface the decidua vera has also 
 disappeared. Here, however, notwithstanding the loss of the ori- 
 ginal mucous membrane, the muscular fibres are not perfectly bare, 
 but are covered with a thin, semi-transparent film, of a whitish color 
 and soft consistency. This film is an imperfect mucous membrane 
 of new formation, which begins to be produced, underneath the 
 old decidua vera, as early as the beginning of the eighth month. 
 We have seen this new mucous membrane very distinctly in the 
 uterus of a woman who died undelivered at the above period. 
 The old mucous membrane, or decidua vera, is at this time some- 
 what opaque, and of a slightly yellowish color, owing to a partial 
 fatty degeneration which it undergoes in the latter months of preg- 
 nancy. It is easily raised and separated from the subjacent parts, 
 owing to the atrophy of its vascular connections; and the new 
 mucous membrane, situated beneath it, is readily distinguished by 
 its fresh color, and healthy, transparent aspect. 
 
 The mucous membrane of the cervix uteri, which takes no part 
 in the formation of the decidua, is not thrown off in parturition, 
 but remains in its natural position ; and after delivery it may be 
 seen to terminate at the os internum by an uneven, lacerated edge, 
 where it was formerly continuous with the decidua. 
 
 Subsequently, a regeneration of the mucous membrane takes place 
 over the whole extent of the body of the uterus. The mucous 
 membrane of new formation, which is already in existence at the 
 time of delivery, becomes thickened and vascular; and glandular 
 tubules are gradually developed in its substance. At the end of 
 two months after delivery, according to Heschl' and Longet,^ it has 
 entirely regained the natural structure of the uterine mucous mem- 
 brane. It unites at the os internum, by a linear cicatrix, with the 
 mucous membrane of the cervix, and the traces of its laceration at 
 
 ' Zeitschrift der K. K. Gesellschaft der Aerzte, in Wien, 1852. 
 * Traite de Physiol ogie. De la Generation, p. 173. 
 
RETROGRADE DEVELOPMENT OF THE UTERUS. 
 
 537 
 
 this spot afterward cease to be visible. At the point, however, 
 where the placenta was attached, the regeneration of the mucoas 
 membrane is less rapid; and a cicatrix-like spot is often visible at 
 this situation for several months after delivery. 
 
 The only further change, which remains to be described in this 
 connection, is the fatty degeneration and reconstruction of the 
 muscular substance of the uterus. This process, which is some- 
 times known as the " involu- 
 tion" of the uterus, takes 
 place in the following man- 
 ner. The muscular fibres 
 of the unimpregnated uterus 
 are pale, flattened, spindle- 
 shaped bodies (Fig. 214) near- 
 ly homogeneous in structure 
 or very faintly granular, and 
 measuring from -^^ to gi^ 
 of an inch in length, by 
 T(T5oo to gtj'oo of an inch in 
 width. During gestation 
 these fibres increase very 
 considerably in size. Their 
 texture becomes much more 
 distinctly granular, and their 
 outlines more strongly mark- 
 ed. An oval nucleus also 
 shows itself in the central 
 part of each fibre. The en- 
 tire walls of the uterus, at 
 the time of delivery, are com- 
 posed of such muscular fibres 
 as these, arranged in circu- 
 lar, oblique, and longitudinal 
 bundles. 
 
 About the end of the first 
 week after delivery, these 
 fibres begin to undergo a 
 fatty degeneration. (Fig. 
 215.) Their granules be- 
 come larger arid more pro- 
 minent, and very soon as- 
 sume the appearance of 
 
 Muscular Fibres op Unimpregnated 
 Uterus; from a woman aged 40, dead of pbihisis 
 pulmonalis. 
 
 Fig. 215. 
 
 Muscular Fibres of Human Uterus, ten 
 days after parturition ; from a woman dead of puer- 
 peral fever. 
 
538 
 
 BISCHAEGE OF THE OVUM. 
 
 Fig. 216. 
 
 molecules of fat, deposited in the substance of the fibre. The fatty- 
 deposit, thus commenced, increases in abundance, and the mole- 
 cules continue to enlarge until they become converted into fully 
 formed oil-globules, which fill the interior of the fibre more or less 
 
 completely, and mask, to a 
 certain extent, its anatomical 
 characters. (Fig. 216.) The 
 universal fatty degeneration, 
 thus induced, gives to the 
 uterus a softer consistency, 
 and a pale yellowish color 
 which is characteristic of it 
 at this period. The muscu- 
 lar fibres which have become 
 altered by the fatty deposit 
 are afterward gradually ab- 
 sorbed and disappear; their 
 place being subsequently 
 taken by other fibres of new 
 
 M0SCCLAR Fibres of Human Uterus, three formation, which already bc- 
 weeks after parturition ; from a woman dead of peri- . i i • 
 
 tonitis. gin to make their appearance 
 
 before the old ones have been 
 completely destroyed. As this process goes on, it results finally 
 in a complete renovation of the muscular substance of the uterus. 
 The organ becomes again reduced in size, compact in tissue, and 
 of a pale ruddy hue, as in the ordinary unimpregnated condition. 
 This entire renewal or reconstruction of the uterus is completed, 
 according to Heschl,' about the end of the second month after 
 delivery. 
 
 ' Op. cit. 
 
DEVELOPMENT OF THE EMBRYO. 
 
 539 
 
 CHAPTER XIV. 
 
 DEVELOPMENT OF THE E M B R YO— N E R V U S SYSTEM, 
 ORGANS OF SENSE, SKELETON, AND LIMBS. 
 
 Fig. 217. 
 
 The first trace of a spinal cord in the embryo consists of the 
 double longitudinal fold or ridge of the blastodermic membrane, 
 which shows itself at an early period, as above described, on each 
 side the median furrow. The two laminas of which this is com- 
 posed, on the right and left sides (Fig. 217, a, b), unite with each 
 other in front, forming a rounded dilatation (c), 
 the cephalic extremity, and behind at c?, forming 
 a pointed or caudal extremity. Near the poste- 
 rior extremity, there is a smaller dilatation, 
 which marks the future situation of the lumbar 
 enlargement of the spinal cord. 
 
 As the laminae above described grow upward 
 and backward, they unite with each other upon 
 the median line, so that the whole is converted 
 into a hollow cylindrical cord, terminating ante- 
 riorly by a bulbous enlargement, and posteriorly 
 by a pointed enlargement; the central cavity 
 which it contains running continuously through 
 it, from front to rear. 
 
 The next change which shows itself is a divi- 
 sion of the anterior bulbous enlargement into caudai extremity 
 three secondary compartments or vesicles (Fig. 
 218), which are partially separated from each other by transverse 
 constrictions. These vesicles are known as the three cerebral vesi- 
 cles, from which all the different parts of the encephalon are after- 
 ward to be developed. The first, or most anterior cerebral vesicle 
 is destined to form the hemispheres; the second, or middle, the 
 tubercula quadrigemina ; and the third, or posterior, the medulla 
 oblongata. All three vesicles are at this time hollow, and their 
 
 Formation of Cere- 
 bro-Spinal Axis — 
 a, b. Spinal cord. c. Ce- 
 phalic extremity. d. 
 
540 
 
 DEVELOPMENT OF THE EMBRYO. 
 
 Fig. 218. 
 
 cavities communicate freely with each other, through the inter- 
 vening constrictions. 
 
 Yerj soon the anterior and the posterior cerebral vesicles suffer 
 a further division ; the middle one remain- 
 ing undivided. The anterior vesicle thus 
 separates into two portions, of which the 
 first, or larger, constitutes the hemispheres, 
 while the second, or smaller, becomes the 
 optic thalami. The third vesicle also sepa- 
 rates into two portions, of which the ante- 
 rior becomes the cerebellum, and the pos- 
 terior the medulla oblongata. 
 
 There are, therefore, at this time, five 
 cerebral vesicles, all of whose cavities com- 
 municate with each other and with the 
 central cavity of the spinal cord. The 
 entire cerebro-spinal axis, at the same time, 
 becomes very strongly curved in an ante- 
 rior direction, corresponding with the ante- 
 rior curvature of the body of the embryo 
 (Fig. 219); so that the middle vesicle, or 
 that of the tubercula quadrigemina, occu- 
 pies a prominent angle at the upper part of 
 the encephalon, while the hemispheres and the medulla oblongata 
 are situated below it, anteriorly and posteriorly. 
 
 At first, it will be observed, the relative size of the various parts 
 of the encephalon is very different from that which 
 they afterward attain in the adult condition. The 
 hemispheres, for example, are hardly larger than 
 the tubercula quadrigemina; and the cerebellum 
 is very much inferior in size to the medulla oblon- 
 gata. Soon afterward, the relative position and size 
 FffiTAL Pig, fire- of the parts bcgiu to alter. The hemispheres and 
 long! Iho°win''g° bra^a tubcrcuk quadrigcmina grow faster than the poste- 
 rior portions of the encephalon ; and the cerebellum 
 becomes doubled backward over the medulla oblon- 
 gata. (Fig. 220.) Subsequently, the hemispheres 
 rapidly enlarge, growing upward and backward, 
 so as to cover in and conceal both the optic thalami and the tuber- 
 cula quadrigemina (Fig. 221); the cerebellum tending in the same 
 way to grow backward, and projecting foriher and farther over the 
 
 Formation of the Cerebro- 
 spinal Axis. — 1. Vesicle of 
 the hemispheres. 2. Vesicle of 
 the tubercula quadrigemina. 3. 
 Vesicle of the medulla oblongata. 
 
 Fig. 
 2 
 
 219. 
 3 
 
 % 
 
 and spinal cord. — 1. 
 Hemispheres. 2. Tu- 
 bercula quadrigemi- 
 na. 3. Cerebellum. 
 4. Medulla oblongata. 
 
NERVOUS SYSTEM. 
 
 541 
 
 medulla oblongata. The subsequent history of the development 
 of the encephalon is little more than a continuation of the same 
 
 Fig. 221. 
 
 F(KTAL Pi«, one and a quai-tor inch 
 long. — 1. Hemispheres. 2. Tubercula. 
 qnadrigemina. 3. Cerebellum. 4. Me- 
 dulla oblongata. 
 
 HnAn OF FcF.TAL Pio. tbrep and a 
 half inches long. — 1. Hemispheres. 3. 
 Cerebellum. 4. Medulla oblongata. 
 
 process ; the relative dimensions of the parts constantly changing, 
 so that the hemispheres become, in the adult condition (Fig. 222), 
 
 Fig. 222. 
 
 Bratx of .\DrLT Pig. — 1. Hemispheres. 3. Cerebellum. 4. Medulla oblongata. 
 
 the largest of all the divisions of the encephalon, while the cere- 
 bellum is next in size, and covers entirely the upper portion of the 
 medulla oblongata. The surfaces, also, of the hemispheres and 
 cerebellum, which were at first smooth, become afterward convoluted ; 
 increasing, in this way, still farther the extent of their nervous 
 matter. In the human foetus, these convolutions begin to appear 
 about the beginning of the fifth month (Longet), and grow con- 
 stantly deeper and more abundant during the remainder of foetal 
 life. 
 
 The lateral portions of the brain growing at the same time more 
 rapidly than that which is situated on the median line, they soon 
 project on each side outward and upward; and, by folding over 
 against each other in the median line, form the right and left hemi- 
 spheres, separated from each other by the longitudinal fissure. 
 
542 DEVELOPMENT OF THE EMBRYO. 
 
 A similar process of growth taking place in tlie spinal cord results 
 in the formation of the two lateral columns and the anterior and pos- 
 terior median fissures of the cord. Elsewhere the median fissure is 
 less complete, as, for example, between the two lateral halves of the 
 cerebellum, the two optic thalami and corpora striata, and the two 
 tubercula quadrigemina; but it exists everywhere, and marks more 
 or less distinctly the division between the two sides of the nervous 
 centres, produced by the excessive growth of their lateral portions. 
 In this way the whole cerebro-spinal axis is converted into a double 
 organ, equally developed upon the right and left sides, and partially 
 divided by a longitudinal median fissure. 
 
 Organs of Special Sense. — The eyes are formed by a diverticulum 
 which grows out on each side from the first cerebral vesicle. This 
 diverticulum is at first hollow, its cavity communicating with that 
 of the hemisphere. Afterward, the passage between the two is filled 
 up with a deposit of nervous matter, and becomes the optic nerve. 
 The globular portion of the diverticulum, which is converted into 
 the globe of the eye, has a very thin layer of nervous matter depo- 
 sited upon its internal surface, which becomes the retina; the rest 
 of its cavity being occupied by a gelatinous semi-fluid substance, 
 the vitreous body. The crystalline lens is formed in a distinct fol- 
 licle, which is an offshoot of the integument, and becomes partially 
 imbedded in the anterior portion of the globe of the eye. The 
 cornea also is originally a part of the integument, and remains 
 partially opaque until a very late period of development. Its tissue 
 clears up, however, and becomes perfectly transparent, shortly be- 
 fore birth. 
 
 The iris is a muscular septum which is formed in front of the 
 crystalline lens, separating the anterior and posterior chambers of 
 the aqueous humor. Its central opening, which afterward becomes 
 the pupil, is at first closed by a vascular membrane, the pupillary 
 membrane^ passing directly across the axis of the eye. The vessels 
 of this membrane, which are derived from those of the iris, subse- 
 quently become atrophied. They disappear first from its centre, 
 and afterward recede gradually toward its circumference; returning 
 always upon themselves in loops, the convexities of which are directed 
 toward the centre of the membrane. The pupillary membrane itself 
 finally becomes atrophied and destroyed, following in this retro- 
 grade process the direction of its receding bloodvessels, viz., from 
 the centre.toward the circumference. It has completely disappeared 
 by the end of the seventh month. (Cruveilhier.) 
 
SKELETON AND LIMBS. 543 
 
 The eyelids are formed by folds of the integument, which 
 gradually project from above and below the situation of the eye- 
 ball. They grow so rapidly during the second and third months 
 that their free margins come in contact and adhere together, so that 
 they cannot be separated at that time without some degree of vio- 
 lence. They remain adherent from this period until the seventh 
 month (Guy), when their margins separate and they become per- 
 fectly free and movable. In the carnivorous animals, however 
 (dogs and cats), the eyelids do not separate from each other until 
 eight or ten days after birth. 
 
 The internal ear is formed in a somewhat similar manner with 
 the eyeball, by an oft'shoot from the third cerebral vesicle; the 
 passage between them filling up by a deposit of white substance, 
 which becomes the auditory nerve. The tympanum and auditory 
 meatus are both offshoots from the external integument. 
 
 Skeleton. — At a very early period of development there appears, 
 as we have already described (Chap. YIL), immediately beneath the 
 cerebro-spinal axis, a cylindrical cord, of a soft, cartilaginous con- 
 sistency, termed the chorda dorsalis. It consists of a fibrous sheath 
 containing a mass of simple cells, closely packed together and 
 united by adhesive material. This cord is not intended to be a 
 permanent part of the skeleton, but is merely a temporary organ 
 destined to disappear as development proceeds. 
 
 Immediately around the chorda dorsalis there are deposited soon 
 afterward a number of cartilaginous plates, which encircle it in a 
 series of rings, corresponding in number with the bodies of the future 
 vertebrae. These rings increase in thickness from without inward, 
 encroaching upon the substance of the chorda dorsalis, and finally 
 taking its place altogether. The thickened rings, which have been 
 filled up in this way and solidified by cartilaginous deposit, become 
 the bodies of the vertebrae ; while their transverse and articulating 
 processes, with the laminae and spinous processes, are formed by 
 subsequent outgrowths from the bodies hi various directions. 
 
 When the union of the dorsal plates upon the median line fails 
 to take place, the spinal canal remains open at that situation, and 
 presents the malformation known as spina bifida. This malforma- 
 tion may consist simply in a fissure of the spinal canal, more or 
 less extensive, in which case it may often be cured, or even close 
 spontaneously; or it may be complicated with an imperfect deve- 
 lopment or complete absence of the spinal cord at the same spot. 
 
544 DEVELOPMENT OF THE EMBRYO. 
 
 when it is accompanied of course by paralysis of the lower ex- 
 tremities, and almost necessarily results in early death. 
 
 The entire skeleton is at first cartilaginous. The first points of 
 ossification show themselves about the beginning of the second 
 month, almost simultaneously in the clavicle and the upper and 
 lower jaw. Then come, in the following order, the long bones of 
 the extremities, the bodies and processes of the vertebrae, the bones 
 of the head, the ribs, pelvis, scapula, metacarpus and metatarsus, 
 and the phalanges of the fingers and toes. The bones of the carpus, 
 however, are all cartilaginous at birth, and do not begin to ossify 
 until a year afterward. The calcaneum and astragalus begin to 
 ossify, according to Cruveilhier, during the latter periods of foetal 
 life, but the remainder of the tarsus is cartilaginous at birth. The 
 lower extremity of the femur begins to ossify, according to the 
 same author, during the last half of the ninth month. The pisiform 
 bone of the carpus is said to commence its ossification later than 
 any other bone in the skeleton, viz., at from twelve to fifteen years 
 after birth. Nearly all the bones ossify from several distinct points ; 
 the ossification spreading as the cartilage itself increases in size, 
 and the various bony pieces, thus produced, uniting with each other 
 at a later period, usually some time after birth. 
 
 The limbs appear, by a kind of budding process, as offshoots of 
 the external layer of the blastodermic membrane. They are at 
 first mere rounded elevations, without any separation between the 
 fingers and toes, or any distinction between the different articula- 
 tions. Subsequently the free extremity of each limb becomes di- 
 vided into the phalanges of the fingers or toes ; and afterward the 
 articulations of the wrist and ankle, knee and elbow, shoulder and 
 hip, appear successively from below upward. 
 
 The posterior extremities, in the human subject, are less rapid in 
 their development than the anterior. Throughout the term of 
 foetal life, indeed, the anterior parts of the body are generally more 
 voluminous than the posterior. The younger the embryo, the larger 
 are the head and upper extremities in proportion to the rest of the 
 body. The lower limbs, and the pelvis more particularly, are very 
 slightly developed in the early periods of growth, as compared with 
 the spinal column, to which they are attached. The inferior ex- 
 tremity of the spinal column, formed by the sacrum and coccyx, pro- 
 jects at this time considerably beyond the pelvis, forming a tail, like 
 that of the lower animals, which is curled forward toward the ab- 
 domen, and terminates in a pointed extremity. Subsequently the 
 
SKELETON AND LIMBS. 545 
 
 pelvis and the muscular parts seated upon it grow so much faster 
 than the sacrum and coccyx, that the latter become concealed 
 under the adjoining soft parts, and the rudimentary tail accordingly 
 disappears. 
 
 The integument o^ the embryo is at first thin, vascular, and ex- 
 ceedingly transparent. It afterward becomes thicker, more opaque, 
 and whitish in color; though even at birth it is more vascular than 
 in the adult condition, and the ruddy color of its abundant capil- 
 lary vessels is then very strongly marked. The hairs begin to 
 appear about the middle of intra-uterine life; showing themselves 
 first upon the eyebrows, and afterward upon the scalp, trunk and 
 extremities. The nails are in process of formation from the third 
 to the fifth month ; and, according to Kolliker, are still covered 
 with a layer of epidermis until after the latter period. The seba- 
 ceous matter of the cutaneous glandules accumulates upon the skin 
 after the sixth month, and forms a whitish, semisolid, oleaginous 
 layer, termed the vernix caseosa, which is most abundant in the 
 flexures of the joints, between the folds of the integument, behind 
 the ears and upon the scalp. 
 
 The cells of the epidermis are repeatedly exfoliated after the first 
 five months of foetal life (Kolliker), and replaced by others, of new 
 formation and of larger size. These exfoliated epidermic cells are 
 found mingled with the sebaceous matter of the vernix caseosa in 
 great abundance. This semi-oleaginous layer, with which the in- 
 tegument is covered, becomes exceedingly useful in the process of 
 parturition, by lubricating the surface of the body, and allowing it 
 to pass easily through the generative passages. 
 
 35 
 
546 DEVELOPMENT OF THE ALIMENTARY CANAL 
 
 CHAPTER XV. 
 
 DEVELOPMENT OF THE ALIMENTARY CANAL AND 
 ITS APPENDAGES. 
 
 We have already seen, in a preceding chapter, that the intestinal 
 canal is formed by the internal layer of the blastodermic membrane, 
 which curves forward on each side, and is thus converted into a 
 nearly straight cylindrical tube, terminating at each extremity in 
 a rounded cul-de-sac, and inclosed by the external layer of the 
 blastodermic membrane. The abdominal walls, however, do not 
 unite with each other upon the median line until long after the 
 forjnation of the intestinal canal ; so that, during a certain period, 
 the abdomen of the embryo is widely open in front, presenting a 
 long oval excavation, in which the nearly straight intestinal tube 
 is to be seen, running from its anterior to its posterior extremity. 
 
 The formation of the stomach takes place in the following man- 
 ner : The alimentary canal, originally straight, soon presents two 
 lateral curvatures at the upper part of the abdomen ; the first to 
 the left, the second to the right. The first of these curvatures be- 
 comes expanded into a wide sac, projecting laterally from the 
 median line into the left hypochondrium, forming the great pouch 
 of the stomach. The second curvature, directed to the right, marks 
 the boundary between the stomach and the duodenum; and the 
 tube at that point becoming constricted and furnished with a circular 
 layer of muscular fibres, is converted into the pylorus. Immedi- 
 ately below the pylorus, the duodenum again turns to the left ; and 
 these curvatures, increasing in number and complexity, form the 
 convolutions of the small intestine. The large intestine forms a 
 spiral curvature ; ascending on the right side, then crossing over 
 to the left as the transverse colon, and again descending on the left 
 side, to terminate by the sigmoid flexure in the rectum. 
 
 The curvatures of the intestinal canal take place, however, in an 
 antero-posterior, as well as in a lateral direction, and may be best 
 studied in a profile view, as in Fig. 223. The abdominal walls are 
 
AND ITS APPENDAGES, 547 
 
 here still imperfectly closed, leaving a wide opening at a h, where 
 the integument of the foetus becomes continuous with the com- 
 mencement of the amniotic membrane. The intestine makes at 
 
 Fiff. 223. 
 
 Formation of Alimentary Canal. — n,b. Commeneement of amnion, c, c. Intestine, d. 
 Pharynx, e. Uiinai y bladder. /. Allautois. g. Umbilical vesicle, x. Dotted line, showing the 
 place of formation of the oesophagus. 
 
 first a single angular turn forward, and opposite the most promi- 
 nent portion of this angle is to be seen the obliterated duct, which 
 forms the stem of the umbilical vesicle. A short distance below 
 this point the intestine subsequently enlarges in its calibre, and the 
 situation of this enlargement marks the commencement of the 
 colon. The two portions of the intestine, after this period, becomie 
 widely different from each other. The upper portion, which is the 
 small intestine, grows mostly in the direction of its- length, and be- 
 comes a very long, convoluted, and narrow tube; while the lower 
 portion, which is the large intestine, increases rapidly in diameter, 
 but elongates less than the former. 
 
 At the point of junction of the small and large intestines, a late- 
 ral bulging or diverticulum of the latter shows itself, and increases 
 in extent, until the ileum seems at last to be inserted obliquely into 
 the side of the colon. This diverticulum of the colon is at first uni- 
 formly tapering or conical in shape ; but afterward that portion 
 which forms its free extremity, becomes narrow and elongated, and 
 is slightly twisted upon itself in a spiral direction, forming the ap- 
 pendix vermiformis; while the remaining portion, which is con- 
 tinuous with the intestine, becomes exceedingly enlarged, and forms 
 the caput coli. 
 
 The ciiput coli and the appendix are at first situated near the um- 
 
548 DEVELOPMENT OF THE ALIMENTARY CANAL 
 
 bilicus; but between the fourth and fifth months (Cruveilhier) their 
 position is altered, and they then become fixed in the right iliac 
 region. During the first six months, the internal surface of the 
 small intestine is smooth. At the seventh month, according to 
 Cruveilhier, the valvulse conniventes begin to appear, after which 
 they increase in size till birth. The division of the colon into sac- 
 culi by longitudinal and transverse bands, is also an appearance 
 which presents itself only during the last half of foetal life. Pre- 
 vious to that time, the colon is smooth and cylindrical in figure, 
 like the small intestine. 
 
 After the small intestine is once formed, it increases very rapidly 
 in length. It grows, indeed, at this time, faster than the walls of 
 the abdomen; so that it can no longer be contained in the abdominal 
 cavity, but protrudes under the form of an intestinal loop, or her- 
 nia, from the umbilical opening. At a subsequent period, on the 
 contrary, the walls of the abdomen grow more rapidly than the 
 intestine. They accordingly gradually envelop the hernial protru- 
 sion, and at last inclose it again in the cavity of the abdomen. 
 
 Owing to an imperfect development of the abdominal walls, and 
 an imperfect closure of the umbilicus, this intestinal protrusion, 
 which is normal during the early stages of foetal life, sometimes 
 remains at birth, and we then have a congenital umbilical hernia. 
 As the parts at that time, however, have a natural tendency to 
 cicatrize and unite with each other, simple pressure is generally 
 effectual, in such cases, in retaining the hernia within the abdomen, 
 and in producing at last a complete cure. 
 
 Urinary Bladder^ Urethra, &c. — It will be recollected that very 
 soon after the formation of the intestine, a vascular outgrowth takes 
 place from its posterior portion, which gradually protrudes from the 
 open walls of the abdomen in front, until it comes in contact with 
 the external investing membrane of the egg, and forms, by its con- 
 tinued growth and expansion, the allantois. (Fig. 228,/.) It is at 
 first, as we have shown above, a hollow sac; but, as it spreads out 
 over the surface of the investing membrane of the egg, its two 
 opposite walls adhere to each other, so that its cavity is obliterated 
 at this situation, and it is thus converted into a single vascular 
 membrane, the chorion. This obliteration of the cavity of the 
 allantois commences at its external portion, and gradually extends 
 inward toward the point of its emergence from the abdomen. The 
 hollow tube, or duct, which connects the cavity of the allantois with 
 the posterior part of the intestine, is accordingly converted, as the 
 
AND ITS APPENDAGES. 549 
 
 process of obliteration proceeds, into a solid, rounded cord. This 
 cord is termed the urachus. 
 
 After the walls of the abdomen have come in contact, and united 
 with each other at the umbilicus, that portion of the above duct 
 which is left outside the abdominal cavity, forms a part of the um- 
 bilical cord, and remains connected with the umbilical arteries and 
 vein. That portion, on the contrary, which is included in the ab- 
 domen, does not close completely, but remains as a pointed fusiform 
 sac, terminating near the umbilicus in the solid cord of the urachus, 
 and still communicating at its base with the lower extremity of the 
 intestinal canal. This fusiform sac (Fig. 223, e), becomes the wn- 
 nary bladder; and in the foetus at term, the bladder is still conical 
 in form, its pointed extremity being attached, by means of the ura- 
 chus, to the internal surface of the abdominal walls at the situation 
 of the umbilicus. Afterward, the bladder loses this conical form, 
 and its fundus in the adult becomes rounded and bulging. 
 
 The urinary bladder, as it appears from the abov^e description, at 
 first communicates freely with the intestinal cavity. The intestine, 
 in fact, terminates, at this time, in a wide passage, or cloaca, at its 
 lower extremity, which serves as a common outlet for the urinary 
 and intestinal passages. Subsequently, however, a horizontal par- 
 tition makes its appearance just above the point of junction between 
 the bladder and rectum, and grows downward and forward in such 
 a manner as to divide the above-mentioned cloaca into two parallel 
 and unequal passages. The anterior or smaller of these passages 
 becomes the urethra, the posterior or larger becomes the rectum; 
 and the lower edge of the septum between them becomes finally 
 united with the skin, forming, at its most superficial part, a tole- 
 rably wide band of integument, the perineum, which intervenes be- 
 tween the anus and the external portion of the urethra. 
 
 The contents of the intestine, which accumulate during foetal life, 
 vary in different parts of the alimentary canal. In the small intes- 
 tine they are semifluid or gelatinous in consistency, of a light 
 yellowish or grayish- white color in the duodenum, becoming yellow, 
 reddish-brown and greenish brown below. In the large intestine 
 they are of a dark greenish hue, and pasty in consistency ; and the 
 contents of this portion of the alimentary canal have received the 
 name of meconium, from their resemblance to inspissated poppy- 
 juice. The meconium contains a large quantity of fat, as well as 
 various insoluble substances, probably the residue of epithelial and 
 mucous accumulations. It does not contain, however, any trace of 
 
550 DEVELOPMEXT OF THE ALIMEXTAEY CAXAL 
 
 the biliary substances (tauro-cholatesand glyko-cholates) when care- 
 fallj examined by Pettenkofer's test ; and cannot therefore properly 
 be regarded, as is sometimes incorrectly asserted, as resulting from 
 the accumulation of bile. In the contents of the small intestine, on 
 the contrary, traces of bile may be found, according to Lehmann,' 
 so early as between the fifth and sixth months. We have also 
 found distinct traces of bile in the small intestine at birth, but it is 
 even then in extremely small quantity, and is sometimes altogether 
 absent. 
 
 The meconium, therefore, and the intestinal contents generally, 
 are not composed principally, or even to any appreciable extent, of 
 the secretions of the liver. They appear rather to be produced by 
 the mucous membrane of the intestine itself. Even their yellowish 
 and greenish color does not depend on the presence of bile, since 
 the yellow color first shows itself, in very 3'Oung foetuses, tibout 
 the middle of the small intestine, and not at its upper extremity. 
 The material which accumulates afterward appears to extend from 
 this point upward and downward, gradually filling the intestine, 
 and becoming, in the ileum and large intestine, darker and more 
 pasty as gestation advances. 
 
 It is a singular fact, perhaps of some importance in this connec- 
 tion, that the amniotic fluid, during the latter half of fcetal life, 
 finds its way, in greater or less abundance, into the stomach, and 
 through that into the intestinal canal. Small cheesy-looking masses 
 may sometimes be found at birth in the fluid contained in the 
 stomach, which are seen on microscopic examination to be no other 
 than portions of the vernix caseosa exfoliated from the skin into 
 the amniotic cavity, and afterward swallowed into the stomach. 
 According to Kcilliker,^ the soft downy hairs of the foetus, exfoliated 
 from the skin, are often swallowed in the same way, and may be 
 found in the meconium. 
 
 The gastric juice is not secreted before birth ; the contents of the 
 stomach being generally in small quantity, clear, nearly colorless, 
 and neutral or alkaline in reaction. 
 
 The liver is developed at a very early period. Its size in pro 
 portion to that of the entire body is, in fact, very much greater in 
 the early months than at birth or in the adult condition. In the 
 fcetal pig we have found the relative size of the liver greatest 
 within the first month, when it amounts to very nearly 12 per cent. 
 
 ' Physiological Chemistry, Philadelphia edition, vol. i. p. 532. 
 * Gewebelehie. Leipzig, 1852, p. 139. 
 
AND ITS APPENDAGES. 551 
 
 of the entire weight of the body. Afterward, as it grows less rapidly 
 than other parts, its relative weight diminishes successively to 10 
 per cent, and 6 per cent. ; and is reduced before birth to 3 or 4 per 
 cent. In the human subject, also, the weight of the liver at birth 
 is between 3 and 4 per cent, of that of the entire body. 
 
 The secretion of hue takes place, as we have intimated above, 
 during foetal life, in a very scanty manner. "We have found it, in 
 minute quantity, in the gall-bladder as well as in the small intes- 
 tine at birth ; but it does not probably take any active part in the 
 nutritive or other functions of the foetus before that period. 
 
 The glycogenic function of the liver commences during foetal life, 
 and at birth the tissue of the organ is abundantly saccharine. It is 
 remarkable, however, that in the early periods of gestation sugar is 
 produced in the foetus from other sources than the liver. In very 
 young foetuses of the pig, for example, both the allantoic and 
 amniotic fluids are saccharine, a considerable time before any sugar 
 makes its appearance in the tissue of the liver. Even the urine, in 
 half grown foetal pigs, contains an appreciable quantity of sugar, 
 and the young animal is therefore, at this period, in a diabetic con- 
 dition. This sugar, however, disappears from the urine before birth, 
 and also from the amniotic fluid, as has been ascertained by M. Ber- 
 nard;' while the liver begins to produce a saccharine substance, and 
 to exercise the glycogenic function, which it continues after birth. 
 
 Development of the Pharynx, (Esophagus, &c. — We have already 
 seen that the intestinal canal consists at first of a cylindrical tube, 
 terminated, at each extremity of the abdominal cavity, by a rounded 
 cul-de-sac (Fig. 223, c, c); and that the openings of the mouth and 
 anus are subsequently formed by perforations which take place 
 through the integument and the intervening tissues, and so estab- 
 lish a communication with the intestinal tube. The formation of 
 the anterior perforation and its appendages takes place in the fol- 
 lowing manner: — 
 
 After the early development of the intestinal tube in the mode 
 above described, the head increases in size out of all proportion to 
 the remainder of the foetus, projecting as a large rounded mass from 
 the anterior extremity of the body, and containing the brain and the 
 organs of special sense. This portion soon bends over toward the 
 abdomen, in consequence of the increasing curvature of the whole 
 body which takes place at this time. In the interior of this 
 
 ' Lemons de Phjsiologie ExpSrimentale, Paris, 1855, p. 398. 
 
552 DEVELOPMENT OF THE ALIMENTARY CANAL 
 
 cephalic mass there is now formed a large cavity (Fig. 223, d\ by 
 the melting down and liquefaction of a portion of its substance. 
 This cavity is the pharynx. It corresponds by its anterior extre- 
 mity to the future situation of the mouth; and by its posterior 
 portion to the upper end of the intestinal canal, the future situation 
 of the stomach. It is still, however, closed on all sides, and does 
 not as yet communicate either with the exterior or with the cavity 
 of the stomach. There is, accordingly, at this time, no thorax 
 whatever; but the stomach lies at the upper extremity of the 
 abdomen, immediately beneath the lower extremity of the pharynx, 
 from which it is separated by a wall of intervening tissue. 
 
 Subsequently, a perforation takes place between the adjacent 
 extremities of the pharynx and stomach, by a short narrow tube, 
 the situation of which is marked by the dotted lines cc, in Fig. 223. 
 This tube afterward lengthens by the rapid growth of that portion 
 of the body in which it is contained, and becomes the oesophagus. 
 Neither the pharynx nor oesophagus, therefore, are, properly speak- 
 ino-, parts of the intestinal canal, formed from the internal layer of 
 the blastodermic membrane; but are, on the contrary, formations 
 of the external layer, from which the entire cephalic mass is pro- 
 duced. The lining membrane of the pharynx and oesophagus is 
 to be regarded, also, for the same reason, as rather a continuation 
 of the integument than of the intestinal mucous membrane; and 
 even in the adult, the thick, whitish, and opaque pavement epithe- 
 lium of the oesophagus may be seen to terminate abruptly, by a 
 well-defined line of demarcation, at the cardiac orifice of the sto- 
 mach ; beyond which, throughout the remainder of the alimentary 
 canal, the epithelium is of the columnar variety, and easily dis- 
 tinguishable by its soft, ruddy, and transparent appearance. 
 
 As the oesophagus lengthens, the lungs are developed on each 
 side of it by a protrusion from the pharynx, which extends and 
 becomes repeatedly subdivided, forming the bronchial tubes and 
 their ramifications. At first, the lungs project into the upper 
 part of the abdominal cavity; for there is still no distinction be- 
 tween the chest and abdomen. Afterward, a horizontal partition 
 begins to form on each side, at the level of the base of the lungs, 
 which gradually closes together at a central point, so as to form 
 the diaphragm, and finally to shut off altogether the cavity of 
 the chest from that of the abdomen. Before the closure of the 
 diaphragm, thus formed, is complete, a circular opening exists on 
 each side the median line, by which the peritoneal and pleural 
 
AND ITS APPENDAGES, 
 
 553 
 
 cavities communicate with each other. In some instances the de- 
 velopment of the diaphragm is arrested at this point, either on one 
 side or the other, and the opening accordingly remains permanent. 
 The abdominal organs then partially protrude into the cavity of 
 the chest on that side, forming congenital diaphragmatic hernia. 
 The lung on the affected side also usually remains in a state of 
 imperfect development. Diaphragmatic hernia of this character is 
 more frequently found upon the left side than upon the right. It 
 may sometimes continue until adult life without causing any serious 
 iuconvenience. 
 
 The heart is formed, at a very early period, directly in front of 
 the situation of the oesophagus. Its size soon becomes very large 
 in proportion to the rest of the body; so that it protrudes beyond 
 the level of the thoracic parietes, covered only by the pericardium. 
 Subsequently, the walls of the thorax, becoming more rapidly 
 developed, grow over it and inclose it. In certain instances, how- 
 ever, they fail to do so, and the heart then remains partially or 
 completely uncovered, in front of the chest, presenting the condi- 
 tion known as ectopia cordis. This malformation is necessarily 
 fatal. 
 
 Development of the Face. — While the lower extremity of the 
 pharynx communicates with the cavity of the stomach, as above 
 described, its upper extremity also becomes perforated in a similar 
 manner, and establishes a communication with the exterior. This 
 perforation is at first wide and gaping. It afterward becomes 
 divided into the mouth and nasal passages; and the different parts 
 of the face are formed round it in the following manner: — 
 
 From the sides of the cephalic mass 
 five buds or processes shoot out, and 
 grow toward each other, so as to approach 
 the centre of the oral orifice above men- 
 tioned. (Fig. 224.) One of them grows 
 directly downward from the frontal region 
 (i), and is called the frontal or inter- 
 maxillary process, because it afterward 
 contains in its lower extremity the inter- 
 maxillary bones, in which the incisor 
 
 HeadofHumaxEmbryo, 
 
 teeth of the upper jaw are inserted. The at about the twentieth day. After 
 next process (2) originates from the side ^"°^''= ^'■°™ ^ specimen iu the 
 
 ^ ^ ^ ^ ° collection of M.Coste.—l. Frontal 
 
 of the opening, and, advancing toward the or intermaxillary process. 2. Pro- 
 
 median line, forms, with its fellow of the -- of ^yi-io-- "-^;>'- s- i'^^- 
 
 ' ' cess of inferior maxiUa. 
 
 Fig. 224. 
 
554 
 
 DEVELOPMENT OF THE ALIMENTAKY CANAL 
 
 opposite side, the superior maxilla. The processes of the remain- 
 ing pair (3) also grow from the side, and form, by their subsequent 
 union upon the median line, the inferior maxilla. The inferior 
 maxillary bone is finally consolidated, in man, into a single piece, 
 but remains permanently divided, in the lower animals, by a suture 
 upon the median line. 
 
 As the frontal process grows from above 
 downward, it becomes double at its lower 
 extremity (Fig. 225), and at the same time 
 two offshoots show themselves upon its 
 sides (1), which curl round and inclose two 
 circular orifices (5), the opening of the an- 
 terior nares; the offshoots themselves be- 
 coming the alas nasi. 
 
 The processes of the superior maxilla 
 continue their growth, but less rapidly than 
 those of the inferior ; so that the two sides 
 of the lower jaw are already consolidated 
 with each other, while those of the upper 
 jaw are still separate. 
 
 As the processes of the superior maxilla 
 continue to enlarge, they also tend to unite 
 with each other on the median line, but are 
 prevented from doing so by the intermax- 
 illary processes which grow down between 
 them. They then unite with the inter- 
 maxillary processes, which have at the same time united with each 
 other, and the upper jaw and lip are thus completed. (Fig. 226.) 
 
 The external edge of the ala nasi also 
 adheres to the superior maxillary pro- 
 cess and unites with it, leaving only a 
 curved crease or furrow, as a sort of 
 cicatrix, to mark the line of union be- 
 tween them. 
 
 Sometimes the superior maxillary 
 and the intermaxillary processes fail to 
 unite with each other; and we then 
 have the malformation known as hare- 
 lip. The fissure of hare-lip, conse- 
 TiEAD OF Human Embryo, about queutly, is ncvcr cxactly in the median 
 
 tbo end of the second month —From a ,. i t „ i;<.*.1„ 4.^ ^v^^ c,\A^ ^P if ,->ti 
 
 ., , line, but a little to one side oi it, on 
 
 specimen in the author's possession. iiuc, uliu c* i.tvi,i.^ uv. vy v/ , 
 
 Head of Human Embryo 
 at the end of the first month. 
 After Longet ; from a specimen 
 in the collection of M. Co-^te — 
 ]. AUnasi. 2. Superior maxilla. 
 .3. Inferior maxilla. 4. Inter- 
 maxillary process. 0. Nostril. 
 6. Eye. 
 
 226. 
 
AND ITS APPENDAGES. 555 
 
 the external edge of the intermaxillary process. Occasionally, the 
 same deficiency exists on both sides, producing "double hare-lip;" 
 in which case, if the fissures extend through the bony structures, 
 the central piece of the superior maxilla, which is detached from 
 the remainder, contains the four upper incisor teeth, and corres- 
 ponds with the intermaxillary bone of the lower animals. 
 
 The eyes at an early period are situated upon the sides of the 
 head, so that they cannot be seen in an anterior view. (Fig. 224.) 
 As development proceeds, they come to be situated farther forward 
 (Fig. 225), their axes being divergent and directed obliquely for- 
 ward and outward. At a later period still they are placed on the 
 anterior plane of the face (Fig. 226) and have their axes nearly 
 parallel and looking directly forward. This change in the situa- 
 tion of the eyes is effected by the more rapid growth of the pos- 
 terior and lateral parts of the head, which enlarge in such a manner 
 as to alter the relative position of the parts seated in front of them. 
 
 The palate is formed by a septum between the mouth and nares, 
 which arises on each side as a horizontal plate or offshoot from the 
 superior maxilla. These two plates afterward unite with each 
 other upon the median line, forming a complete partition between 
 the oral and nasal cavities. The right and left nasal passages are 
 also separated from each other by a vertical plate (vomer), which 
 grows from above downward and fuses with the palatal plates be- 
 low. Fissure of the palate is caused by a deficiency, more or less 
 complete, of one of the horizontal maxillary plates. It is accord- 
 ingly situated a little to one side of the median line, and is fre- 
 quently associated with hare-lip and fissure of the upper jaw. The 
 fissures of the palate and the lip are very often continuous with 
 each other. 
 
 The anterior and posterior pillars of the fauces are incomplete 
 vertical partitions, which grow from the sides of the oral cavity, 
 and tend to separate, by a slight constriction, the cavity of the 
 mouth from that of the pharynx. 
 
 When all the above changes are accomplished, the pharynx, 
 oesophagus, mouth, nares, and fauces, with their various projections 
 and divisions, have been successively formed; and the development 
 of the upper part of the alimentary, canal is then complete. 
 
556 
 
 DEVELOPMENT OF THE KIDNEYS. 
 
 CHAPTER XVI. 
 
 DEVELOPMENT OF THE KIDNEYS, WOLFFIAN 
 BODIES, AND INTERNAL ORGANS OF GENE- 
 RATION. 
 
 The first trace of a urinary apparatus in the embryo, consists of 
 two long, fusiform bodies, which make their appearance in the ab- 
 domen at a very early period, situated on each side the spinal 
 column. I^ese are known by the name of the Wolffian bodies. 
 They are fully formed, in the human subject, toward the end of the 
 first month (Coste), at which time they are the largest organs in the 
 cavity of the abdomen, extending from just below the heart, nearly 
 to the posterior extremity of the body. In the foetal pig, when a 
 little over half an inch in length (Fig. 227), the Wolffian bodies are 
 rounded and kidney-shaped, and occupy a very large part of the 
 abdominal cavity. Their importance may be estimated from the 
 fact that their weight at this time is equal to 
 a little over -3-^3 of that of the entire body — a 
 proportion which is seven or eight times as 
 large as that of the kidneys, in the adult 
 condition. There are, indeed, at this period, 
 only three organs perceptible in the abdo- 
 men, viz., the liver, which has begun to be 
 formed at the upper part of the abdominal 
 cavity; the intestine, which is already some- 
 what convoluted, and occupies its central 
 portion ; and the Wolffian bodies, which pro- 
 ject on each side the spinal column. 
 
 The WolflBan bodies, in their intimate 
 structure, resemble very closely the adult 
 kidney. They consist of secreting tubules, 
 lined with epithelium, which run from the 
 outer toward the inner edge of the organ, terminating at their free 
 extremities in small rounded dilatations, or culs-de-sac. Into each 
 
 FfETALPiu, 5^ of an inch 
 long; from a specimen in the 
 autlior's possession. 1. Heart. 
 2. Anterior extremity. 3. Pos- 
 terior extremity. 4. Wolfiian 
 body The abdominal walls 
 have been cut away, in order 
 to show the position of the 
 Wolffian bodies 
 
WOLFFIAN BODIES. 557 
 
 of these dilated extremities is received a globular coil of capillary 
 bloodvessels, or glomerulus, similar to that of the adult kidney. 
 The tubules of the Wolffian body all empty into a common excre- 
 tory duct, which leaves the organ at its lower extremity, and com- 
 municates afterward with the lower part of the intestinal canal, just 
 at the point where the diverticulum of the allantois is given off", and 
 where the urinary bladder is afterward to be situated. The prin- 
 cipal, if not the only distinction, between the minute structure of 
 the Wolffian bodies and that of the true kidneys, consists in the 
 size of the tubules and of their glomeruli, these elements being 
 considerably larger in the Wolffian body, than in the kidney. In 
 the foetal pig, for example, about an inch and a half in length, the 
 diameter of the tubules of the Wolffian body is 5^^ of an inch, 
 while in the kidney of the same foetus, the diameter of the tubules 
 is only ^i^ of an inch. The glomeruli in the Wolffian bodies 
 measure ^'^ of an inch in diameter, wbile those of the kidney mea- 
 sure only y| of an inch. The Wolffian bodies are therefore urinary 
 organs, so far as regards their anatomical structure, and are some- 
 times known, accordingly, by the name of the "false kidneys." 
 There is little doubt that they perform, at this early period, a func- 
 tion analogous to that of the kidneys, and separate from the blood 
 of the embryo an excrementitious fluid which is discharged by the 
 ducts of the organ into the cavity of the allantois. 
 
 Subsequently, the Wolffian bodies increase for a time in size, 
 though not so rapidly as the rest of the body; and consequently 
 their relative magnitude diminishes. Still later, they begin to 
 suffer an absolute diminution or atrophy, and become gradually 
 less and less perceptible. In the human subject, they are hardlv 
 to be detected after the end of the second month (Longet), and in 
 the quadrupeds also they disappear completely long before birth. 
 They are consequently foetal organs, destined to play an important 
 part during a certain stage of development, but to become after- 
 ward atrophied and absorbed, as the physiological condition of the 
 foetus alters. During the period, however, of their retrogression 
 and atrophy, other organs appear in their neighborhood, which 
 become afterward permanently developed. These are, first, the 
 kidneys, and secondly, the internal organs of generation. 
 
 The kidneys are formed just behind the Wolffian bodies, and are 
 at first entirely concealed by them in a front view, the kidneys 
 being at this time not more than a fourth or a fifth part the size of 
 
558 
 
 DEVELOPMENT OF THE KIDNEYS. 
 
 FfETAL PiQ, one and a half 
 inches long. From a specimen in 
 the author's possession. — 1. Wolffian 
 body. 2. Kidney. 
 
 the Wolffian bodies. (Fig. 228.) As the kidneys, however, subse- 
 quently enlarge, while the Wolffian bodies diminish, the propor- 
 tions existing between the two organs are 
 reversed; and the Wolffian bodies at last 
 come to be mere small rounded or ovoid 
 masses, situated on the anterior surface 
 of the kidneys. (Figs. 229 and 230.) The 
 kidneys, during this period, grow more 
 rapidly in an upward than in a downward 
 direction, so that the Wolffian bodies 
 come to be situated near their inferior 
 extremity, and seem to have performed 
 a sliding movement from above down- 
 ward, over their anterior surface. This 
 apparent sliding movement, or descent 
 of the AYolffian bodies, is owing entirely 
 to the rapid growth of the kidneys in an 
 upward direction, as we have already explained. 
 
 The kidneys, during the succeeding periods of foetal life, become 
 in their turn very largely developed in proportion to the rest of 
 the organs; attaining a size, in the foetal pig, equal to ^^ (in weight) 
 of that of the entire body. This proportion, however, diminishes 
 again very considerably before birth, owing to the increased deve- 
 lopment of other parts. In the human foetus at birth, the weight 
 of the two kidneys taken together is y^g that of the entire body. 
 . Internal Organs of Generation. — About the same time that the kid- 
 neys are formed behind the Wolffian bo- 
 dies, two oval shaped organs make their 
 appearance in front, on the inner side of 
 the Wolffian bodies and between them and 
 the spinal column. These bodies are the 
 internal organs of generation ; viz., the 
 testicles in the male, and the ovaries in 
 the female. At first they occupy pre- 
 cisely the same situation and present 
 precisely the same appearance, whether 
 IXT.RXAT.OROAXS OF nK>-K- tijgfoetus Is aftcrwardto belong to the 
 
 KATioN, &c. ; lu a foetal pig three ° 
 
 inches long. From a specimen in the male Or the fcmalc SCX. (Fig. 229.) 
 author's Possession. — 1,1. Kidneys. \ ^ i. j- i. i, j.i • j. ^ 
 
 2,2. Wolffian bodies. .3,3. Internal ^ ^hort distancc abovc thc mtcmal 
 organsofgeneration; testicles or ova- orgaDS of generation there commenccs, 
 
 ries. 4. Urinary bladder, turned over i • i , i i j 
 
 iu front. 5. -Intestine. ou cach Side, a narrow tube or duct, 
 
MALE ORGANS OF GENERATION. 559 
 
 which runs from above downward along the anterior border of the 
 Wolffian body, immediately in front of and parallel with the excre- 
 tory duct of this organ. The two tubes, right and left, then approach 
 each other below; and, joining upon the median line, empty, together 
 with the ducts of the Wolffian bodies, into the base of the allantois, 
 OT what will afterward be the base of the urinary bladder. These 
 tubes serve as the excretory ducts of the internal organs of genera- 
 tion ; and will afterward become the vasa deferentia in the male, and 
 the Fallopian tubes in the female. According to Coste, the vasa de- 
 ferentia at an early period are disconnected with the testicles ; and 
 originate, like the Fallopian tubes, by free extremities, presenting 
 each an open orifice. It is only afterward, according to the same 
 author, that the vasa deferentia become adherent to the testicles, and 
 a communication is established between them and the tubuli serni- 
 niferi. In the female, the Fallopian tubes remain permanently 
 disconnected with the ovaries, except by the edge of the fimbriated 
 extremity ; which in many of the lower animals becomes closely 
 adherent to the ovary, and envelopes it more or less completely. 
 
 Male Organs of Generation ; Descent of the Testicles. — In the male 
 foetus there now commences a movement of translation, or change 
 of place, in the internal organs of generation, which is known as 
 the " descent of the testicles." In consequence of this movement, 
 the above organs, which are at first placed near the middle of the 
 abdomen, and directly in front of the kidneys, come at last to be 
 situated in the scrotum, altogether outside and below the abdominal 
 cavity. They also become inclosed in a distinct serous sac of their 
 own, the tunica vaginalis testis. This apparent movement of the 
 testicles is accomplished in the same manner as that of the Wolf- 
 fian bodies, above mentioned, viz., by a disproportionate growth of 
 the middle and upper portions of the abdomen and of the organs 
 situated above the testicles, so that the relative position of these or- 
 gans becomes altered. The descent of the testicles is accompanied 
 by certain other alterations, in the organs themselves and their ap- 
 pendages, which take place in the following manner. 
 
 By the upward enlargement of the kidneys, both the Wolffian 
 bodies and the testicles are soon found to be situated near the 
 lower extremity of these organs. (Fig. 230.) At the same time, a 
 slender rounded cord (not represented in the figure) passes from 
 the lower extremity of each testicle in an outward and downward 
 direction, crossing the corresponding vas deferens a short distance 
 above its union with its fellow of the opposite side. Below this 
 
660 
 
 DEVELOPMENT OF THE KIDNEYS. 
 
 Internal Organs of Generation, 
 &c , in a foetal pig nearly four inches long. 
 From a specimen in the author's possession. — 
 1, 1 Kidneys. 2, 2. Wolffian bodies. 3, 3. 
 Testicles. 4. Urinary bladder. 5. Intestine. 
 
 converted into the epididymis. 
 
 point, the cord spoken of continues to run obliquely outward and 
 downward ; and, passing through the abdominal walls at the situ- 
 ation of the inguinal canal, is inserted into the subcutaneous tissues 
 
 near the symphysis pubis. The 
 lower part of this cord becomes 
 the gubernaculum testis ; and mus- 
 cular fibres are soon developed in 
 its substance which may be easily 
 detected, even in the human foetus, 
 during the latter half of gestation. 
 At the period of birth, however, 
 or soon afterward, these muscular 
 fibres disappear and can no longer 
 be recognized. 
 
 All that portion of the excre- 
 tory tube of the testicle which is 
 situated outside the crossing of the 
 gubernaculum, is destined to be- 
 come afterward convoluted, and 
 That portion which is situated in- 
 side the same point remains comparatively straight, but becomes 
 considerably elongated, and is finally known as the vas deferens. 
 
 As the testicles descend still farther in the abdomen, they con- 
 tinue to grow, while the Wolffian bodies, on the contrary, diminish 
 rapidly in size, until the latter become much smaller than the tes- 
 ticles ; and at last, when the testicles have arrived at the internal 
 inguinal ring, the Wolffian bodies have altogether disappeared, or 
 at least have become so much altered that their characters are no 
 longer recognizable. In the human foetus, the testicles arrive at 
 the internal inguinal ring, about the termination of the sixth month 
 (Wilson). 
 
 During the succeeding month, a protrusion of the peritoneum 
 takes place through the inguinal canal, in advance of the testicle ; 
 while the last named organ still continues its descent. As it then 
 passes downward into the scrotum, certain muscular fibres are given 
 off from the lower border of the internal oblique muscle of the 
 abdomen, growing downward with the testicle, in such a manner as 
 to form a series of loops upon it, and upon the elongating spermatic 
 cord. These loops constitute afterward the cremaster muscle. 
 
 At last, the testicle descends fairly to the bottom of the scrotum, 
 the gubernaculum constantly shortening, and the vas deferens 
 
MALE ORGANS OF GENERATION". 
 
 561 
 
 elongating as it proceeds. The convoluted portion of the efferent 
 duct, viz., the epididymis, then remains closely attached to the body 
 of the testicle ; while the vas deferens passes upward, in a reverse 
 direction, enters the abdomen through the inguinal canal, again 
 bends downward, and joins its fellow of the opposite side; after 
 which they both open into the prostatic portion of the urethra, 
 upon the median line, by a common orifice (sinus pocularis). At 
 the same time, two diverticula arise from the median portion of the 
 vasa deferentia, and, elongating in a backward direction, underneath 
 the base of the bladder, become developed into two compound 
 sacculated reservoirs — the vesiculoe seminales. 
 
 The left testicle is a little later in its descent than the right, but 
 it afterward passes farther into the scrotum, and, in the adult condi- 
 tion, usually hangs a little lower than its fellow of the opposite side. 
 
 After the testicle has fairly passed into the scrotum, the serous 
 pouch, which preceded its descent, remains for a time in communi- 
 cation with the peritoneal cavity. In many of the lower animals, 
 as, for example, the rabbit, this condition is permanent ; and the 
 testicle, even in the adult animal, may be alternately drawn down- 
 ward into the scrotum, or retracted into the abdomen, by the action 
 of the gubernaculum and the cremaster muscle. But in the human 
 foetus, the two opposite surfaces of the peritoneal pouch, covering 
 the testicle, approach each other at the inguinal canal, forming at 
 that point a constriction or neck, which partly shuts off the testicle 
 from the cavity of the abdomen. By a 
 continuation of this process, the serous 
 surfaces come actually in contact with 
 each other, and, adhering together at 
 this situation (Fig. 281, 4), form a kind 
 of cicatrix, or umbilicus, by the complete 
 closure and consolidation of which the 
 cavity of the tunica vaginalis (2) is finally 
 shut off altogether from the general cavity 
 of the peritoneum (3). The tunica vagi- 
 nalis testis is, therefore, originally a part 
 of the peritoneum, from which it is sub- 
 sequently separated by the process just 
 described. 
 
 The separation of the tunica vaginalis 
 from the peritoneum is usually completed 
 
 in the human subject before birth. But sometimes it fails to take 
 36 
 
 Fig. 231. 
 
 Formation of Tunica Va- 
 ginalis Testis.— 1. Testicle^ 
 nearly at the bottom of the scro- 
 tum. 2. Cavity of tunica Tdginali.K, 
 3. Cavity of peritoneum. 4. Obliter- 
 ated neck of peritoneal sac. 
 
562 DEVELOPMENT OF THE KIDNEYS, ETC. 
 
 place at the proper time, and the intestine is then apt to protrude 
 into the scrotum, in front of the spermatic cord, giving rise, in this 
 way, to a congenital inguinal hernia. (Fig. 232.) The parts impli- 
 cated, however, in this malformation, have 
 ^^' still, as in the case of congenital umbili- 
 
 cal hernia, a tendency to unite with each 
 other and obliterate the unnatural open- 
 ings ; and if the intestine be retained by 
 pressure in the cavity of the abdomen, 
 cicatrization usually takes place at the 
 inguinal canal, and a cure is effected. 
 
 The descent of the testicle, above de- 
 scribed, is not accomplished by the forci- 
 ble traction of the muscular fibres of the 
 co.v<iE. VITAL Inguinal hee- g-ubemaculum, as has been described bv 
 
 .VIA.— 1. Testicle. 2, 2, 2. Intes- ° . ■ i i • i 
 
 tine. certam writers, but by a simple process 
 
 of growth taking place in different parts, 
 in different directions, at successive periods of foetal life. The 
 gubernaculum, accordingly, has no proper function as a muscular 
 organ, in the human subject, but is merely the anatomical vestige, 
 or analogue, of a corresponding muscle in certain of the lower 
 animals, where it has really an important function to perform. For 
 in them, as we have already mentioned, both the gubernaculum 
 and the cremaster remain fully developed in the adult condition, 
 and are then employed to elevate and depress the testicle, by the 
 alternate contraction of their muscular fibres. 
 
 Female Organs of Generation. — At an early period, as we have 
 mentioned above, the ovaries have the same external appearance, 
 and occupy the same position in the abdomen, as the testicles in the 
 opposite sex. The descent of the ovaries also takes place, to a great 
 extent, in the same manner with the descent of the testicles. When, 
 in the early part of this descent, they have reached the level of the 
 lo^y■er edge of the kidneys, a cord, analogous to the gubernaculum, 
 may be seen proceeding from their lower extremity, crossing the 
 efferent duct on each side, and passing downward, to be attached 
 to the subcutaneous tissues at the situation of the inguinal ring. 
 That part of the duct situated outside the crossing of this cord, 
 heQomQ'i afterward convoluted, and is converted into the Fallopian 
 lube; while that part which is inside the same point, becomes con- 
 verted into the uterus. The upper portion of the cord itself becomes 
 
FEMALE ORGANS OF GENERATION. 563 
 
 the ligament of the ovary; its lower portion, \\\q round ligament of the 
 xUerus. 
 
 As the ovaries continue their descent, they pass below and be- 
 hind the Fallopian tubes, which necessarily perform at the same 
 time a movement of rotation, from before backward and from 
 above downward ; the whole, together with the ligaments of the 
 ovaries and the round ligaments, being enveloped in double folds 
 of peritoneum, which enlarge with the growth of the parts them- 
 selves, and constitute finally the hroad ligaments of the uterus. 
 
 It will be seen from what has been said above, that the situation 
 occupied by the Wolffian bodies in the female is always the space 
 between the ovaries and the Fallopian tubes; for the Wolffian bodies 
 accompany the ovaries in their descent, just as, in the male, they 
 accompany the testicles. As these bodies now become gradually 
 atrophied, their glandular structure disappears altogether; but 
 their bloodvessels, in many instances, remain as a convoluted vas- 
 cular plexus, occupying the situation above mentioned. The 
 Wolffian bodies may therefore be said, in these instances, to un- 
 dergo a kind of vascular degeneration. This peculiar degeneration 
 is quite evident in the Wolffian bodies of the foetal pig, some time 
 before the organs have entirely lost their original form. In the 
 cow, a collection of convoluted bloodvessels may be seen, even in 
 the adult condition, near the edge of the ovary and between the 
 two folds of peritoneum forming the broad ligament. These are 
 undoubtedly vestiges of the Wolffian bodies, which have under- 
 gone the vascular degeneration above described. 
 
 While the above changes are taking place in the adjacent organs, 
 the two lateral halves of the uterus fuse with each other more and 
 more upon the median line, and become covered with an exces- 
 sively developed layer of muscular fibres. In the lower animals, 
 the uterus remains divided at its upper portion, running (jut into 
 two long conical tubes or cornua (Fig. 165), presenting the form 
 known as the uterus bicornis. In the human subject, however, the 
 fusion of the two lateral halves of the organ is nearly complete ; 
 so that the uterus presents externally a rounded, but somewhat 
 flattened and triangular figure (Fig. 166). with the ligaments of the 
 ovary and the round ligaments passing off from its superior angles. 
 But, internally, the cavity of the organ still presents a strongly 
 marked triangular form, the vestige of its original division. 
 
 Occasionally the human uterus, even in the adult condition, re- 
 
564 DEVELOPMENT OF THE KIDXEYS, ETC. 
 
 mains divided into two lateral portions by a vertical septum, which 
 runs from the middle of its fundus downward toward the os in- 
 ternum. This septum may even be accompanied by a partial 
 external division of the organ, corresponding with it in direction, 
 and producing the malformation known as " uterus bicoruis," or 
 " double uterus." 
 
 . The OS internum and os externum are produced by partial con- 
 strictions of the original generative passage; and the anatomical 
 distinctions between the body of the uterus, the cervix and the 
 vagina are produced by the different development of the mucous 
 membrane and muscular tunic in its corresponding portions. 
 During foetal life, however, the neck of the uterus grows much 
 faster than its body ; so that, at the period of birth, the entire or- 
 gan is very far from presenting the form which it exhibits in the 
 adult condition. In the human foetus at term, the cervix uteri 
 constitutes nearly two-thirds of the entire length of the organ ; 
 while the body forms but little over one-third. The cervix, at 
 this time, is also much larger in diameter than the body ; so that 
 the whole organ presents a tapering form from below upward. 
 The arbor vitse uterina of the cervix is at birth very fully de- 
 veloped, and the mucous membrane of the body is also thrown into 
 three or four folds which radiate upward from the os internum. 
 The cavity of the cervix is filled with a transparent semi-solid 
 mucus. 
 
 The position of the uterus at birth is also different from that 
 which it assumes in adult life ; nearly the entire length of the organ 
 being above the level of the symphysis pubis, and its inferior ex- 
 tremity passing below that point only by about a quarter of an 
 inch. It is also slightly anteflexed at the junction of the body and 
 cervix. After birth, the uterus, together with its appendages, con- 
 tinues to descend ; until, at the period of puberty, its fundus is 
 situated just below the level of the symphysis pubis. 
 
 The ovaries at birth are narrow and elongated in form. They 
 contain at this time an abundance of eggs; each inclosed in a 
 Graafian follicle, and averaging ^\^ of an inch in diameter. The 
 vitellus, however, is imperfectly formed in most of them, and in 
 some is hardly to be distinguished. The Graafian follicle at this 
 period envelopes each egg closely, there being nothing between its 
 internal surface and the exterior of the egg, excepting the thin 
 layer of cells forming the "membrana granulosa." Inside this 
 
FEMALE ORGANS OF GENERATION. 565 
 
 layer is to be seen the germinative vesicle, with the germinative 
 spot, surrounded by a faintly granular vitellus, more or less 
 abundant in different parts. Some of the Graafian follicles con- 
 taining eggs are as large as ^^^ of an inch; others as small as tij'ss- 
 In the very smallest, the cells of the membrana granulosa appear 
 to fill entirely the cavity of the follicle, and no vitellus or germina- 
 tive vesicle is to be seen. 
 
566 DEVELOPMENT OF THE CIRCULATORY APPARATUS. 
 
 CHAPTER XVII. 
 
 DEVELOPMENT OF THE CIRCULATORY APPARATUS. 
 
 There are three distinct forms or phases of development assumed 
 by the circulatory system during different periods of life. These 
 different forms of the circulation are intimately connected with the 
 manner in which nutrition and respiration, or the renovation of the 
 blood, are accomplished at different epochs ; and they follow each 
 other in the progress of development, as different organs are em- 
 ployed in turn to accomplish the above functions. The first form 
 is that of the vitelline circulation, which exists at a period when the 
 vitellus, or the umbilical vesicle, is the sole source of nutrition for 
 the foetus. The second is the placental circulation, which lasts 
 through the greater part of foetal life, and is characterized by the 
 existence of the placenta; and the third is the complete or adult 
 circulation, in which the renovation and nutrition of the blood are 
 provided for by the lungs and the intestinal canal. 
 
 First, or Vitelline Circulation. — It has already been shown in a 
 previous chapter, that when the body of the embryo has begun to 
 be formed in the centre of the blastodermic membrane, a number 
 of bloodvessels shoot out from its sides, and ramify over the 
 remainder of the vitelline sac, forming, by their inosculation, an 
 abundant vascular plexus. The area occupied by this plexus in the 
 blastodermic membrane around the foetus is, as we have seen, the 
 " area vasculosa." In the egg of the fowl (Fig. 233), the plexus is 
 limited, on its external border, by a terminal vein or sinus — the 
 "sinus terminalis"; and the blood of the embryo, after circulating 
 through the capillaries of the plexus, returns by several venous 
 branches, the two largest of which enter the body near its anterior 
 and posterior extremities. The area vasculosa is, accordingly, a 
 vascular appendage to the circulatory apparatus of the embryo, 
 spread out over the surface of the vitellus for the purpose of absorb- 
 ing from it the nutritious material requisite for the growth of the 
 newly-formed tissues. In the egg of the fish (Fig. 234), the princi- 
 
VITELLINE CIRCULATION. 
 
 567 
 
 pal vein is seen passing up in front underneath the head ; while the 
 arteries emerge all along the lateral edges of the body. The entire 
 vitellus, in this way, becomes covered with an abundant vascular 
 
 Fig. 233. 
 
 Eoo OF Fowl in process of development, showing area .vasculosa, with .vitelline circulation, 
 terminal sinus, &c. 
 
 network, connected with the internal circulation of the foetus by 
 arteries and veins. 
 
 Very soon, as the embryo and the entire egg increase in size, 
 there are two arteries and two veins which become 
 larger than the others, and which subsequently 
 do the whole work of conveying the blood of 
 the foetus to and from the area vasculosa. These 
 two arteries emerge from the lateral edges of 
 the foetus, on the right and left sides ; while the 
 two veins re-enter at about the same point, and 
 nearly parallel with them. These four vessels are 
 then termed the omphalo-mesenteric arteries and 
 veins. 
 
 The arrangement of the circulatory apparatus 
 in the interior of the body of the foetus, at this time, is as follows: 
 The heart is situated on the median line, just beneath the head and 
 in front of the oesophagus. It receives at its lower extremity the 
 trunks of the two omphalo-mesenteric veins, and at its upper 
 extremity divides into two vessels, which, arching over backward, 
 attain the anterior surface of the vertebral column, and then run 
 from above downward along the spine, quite to the posterior 
 extremity of the foetus. These arteries are called the vertebral 
 arteries^ on account of their course and, situation, running parallel 
 
 EoG OF Fish ( Jar- 
 rabacca), showing vitel- 
 line circulation. 
 
568 DEVELOPMENT OF THE CIRCULATORY APPARATUS. 
 
 with the vertebral column. They give off, throughout their course, 
 many small lateral branches, which supply the body of the fcetus, 
 and also two larger branches — the oraphalo-raesenteric arteries — 
 which pass out, as above described, into the area vasculosa. The 
 two vertebral arteries remain separate in the upper part of the body, 
 but soon fuse with each other a little below the level of the heart : 
 so that, below this point, there remains afterward but one large 
 artery, the abdominal aorta, running from above downward along 
 the median line, giving off the omphalo-mesenteric arteries to the 
 area vasculosa, and supplying smaller branches to the body, the 
 walls of the intestine, and the other organs of the foetus. 
 
 The above description shows the origin and formation of the first 
 or vitelline circulation. A change, however, now begins to take 
 place, by which the vitellus is superseded, as an organ of nutrition, 
 by the placenta, which takes its place; and the second or jjlacental 
 circulation becomes established in the following manner: — 
 
 Second Circulation. — After the umbilical vesicle has been formed 
 by the process already described, a part of the vitellus remains 
 included in it, while the rest is retained in the abdomen and inclosed 
 
 in the intestinal canal. As these 
 two organs (umbilical vesicle and 
 intestine) are originally parts of 
 the same vitelline sac, they remain 
 supplied by the same vascular 
 system, viz : the omphalo-mesen- 
 teric vessels. Those which remain 
 within the abdomen of the foetus 
 supply the mesentery and intes- 
 tine ; but the larger trunks pass 
 outward, and ramify upon the 
 walls of the umbilical vesicle. 
 (Fig. 235.) At first, there are, 
 as we have mentioned above, 
 
 Diagram ofYouNoEMBRYOANDiTS 
 Vessels, showing circulation of umbilical tWO OmphalO-meSCnteriC artcriCS 
 
 vesicle, and also that of aiiantois, beginning to emerging from the body, and two 
 
 be formed. . . 
 
 omphalo-mesenteric veins return- 
 ing to it; but soon afterward, the two arteries are replaced by a 
 common trunk, while a similar change takes place in the two veins- 
 Subsequently, therefore, there remains but a single artery and a 
 single vein, connecting the internal and external portions of the 
 vitelline circulation. 
 
 Fig. 235. 
 
PLACENTAL CIECULATION 
 
 569 
 
 The vessels belonging to this system are therefore called the 
 omphalo-mesenteric vessels, because a part of them (omphalic ves- 
 sels) pass outward, by the umbilicus, or " omphalos," to the umbili- 
 cal vesicle, while the remainder (mesenteric vessels) ramify upon 
 the mesentery and the intestine. 
 
 At first, the circulation of the umbilical vesicle is more import- 
 ant than that of the intestine ; and the omphalic artery and vein 
 appear accordingly as large trunks, of which the mesenteric ves- 
 sels are simply small branches. (Fig. 235.) Afterward, however, 
 the intestine rapidly enlarges, while the umbilical vesicle dimi- 
 nishes, and the proportions existing between the two sets of vessels 
 are therefore reversed. (Fig. 236.) The mesenteric vessels then 
 
 Fig. 236. 
 
 Diagram of Embryo and its Vessels; showing the second circulation. The pharynx, oeso- 
 phagus, and intestinal canal, have become further developed, and the mesenteric arteries have en- 
 larged, while the umhilical vesicle and its branches are vei'y much reduced in size. The large um- 
 bilical arteries are seen passing out to the placenta. 
 
 come to be the principal trunks, while the omphalic vessels are 
 simply minute branches, running out along the slender cord of the 
 umbilical vesicle, and ramifying in a few scanty twigs upon its 
 surface. 
 
 In the mean time, the allantois is formed by a protrusion from 
 the lower extremity of the intestine, which, carrying with it two 
 
570 DEVELOPMENT OF THE CIRCULATORY APPARATUS. 
 
 arteries and two veins, passes out by the anterior opening of the 
 body, and comes in contact with the external membrane of the egg. 
 The arteries of the allantois, which are termed the umbilical arte- 
 ries, are supplied by branches of the abdominal aorta; the umbi- 
 lical veins, on the other hand, join the mesenteric veins, and empty 
 with them into the venous extremity of the heart. As the umbi- 
 lical vesicle diminishes, the allantois enlarges; and the latter soon 
 becomes converted, in the human subject, into a vascular chorion, 
 a part of which is devoted to the formation of the placenta. (Fig. 
 236.) As the placenta soon becomes the only source of nutrition 
 for the foetus, its vessels are at the same time very much increased 
 in size, and preponderate over all the other parts of the circulatory 
 system. During the early periods of the formation of the placenta, 
 there are, as we have stated above, two umbilical arteries and two 
 umbilical veins. But subsequently one of the veins disappears, and 
 the whole of the blood is returned to the body of the foetus by the 
 other, which becomes enlarged in proportion. For a long time 
 previous to birth, therefore, there are in the umbilical cord two 
 umbilical arteries, and but a single umbilical vein. 
 
 Such is the second, or placental circulation. It is exchanged, at 
 the period of birth, for the third or adult circulation, in which the 
 blood which had previously circulated through the placenta, is 
 diverted to the lungs and the intestine. These are the organs 
 upon which the whole system afterward depends for the nourish- 
 ment and renovation of the blood. 
 
 During the occurrence of the above changes, certain other altera- 
 tions take place in the arterial and venous systems, which will now 
 require to be described by themselves. 
 
 Development of the Arterial System.— At an early period of deve- 
 lopment, as we have shown above, the principal arteries pass off 
 from the anterior extremity of the heart in two arches, which curve 
 backward on each side, from the front of the body toward the ver- 
 tebral column, after which they again become longitudinal in direc- 
 tion, and receive the name of "vertebral arteries." Yery soon 
 these arches divide successively into two, three, four, and five 
 secondary arches, placed one above the other, along the sides of 
 the neck. (Fig, 237.) These are termed the cervical arches. In the 
 fish, these cervical arches remain permanent, and give off from their 
 convex borders the branchial arteries, in the form of vascular tufts, 
 to the gills on each side of the neck ; but in the human subject and 
 the quadrupeds, the branchial tufts are never developed, and the 
 
DEVELOPMENT OF THE ARTERIAL SYSTEM. 
 
 571 
 
 cervical arches, as well as the trunks with which they are con- 
 nected, become modified by the progress of development in the 
 followin": manner: — 
 
 Fig. 237. 
 
 Fig. 238. 
 
 Early condition of A R T E R I A i, System; 
 showing the heart (1), with its two ascend- 
 ing arterial trunks, giving off on each side 
 five cervical arches, which terminate in the 
 vertebral arteries (2, 2). The vertebral arte- 
 ries unite below the heart to form the 
 aorta (3). 
 
 Adult condition of Aiitertai. Sys- 
 tem. — 1,1 Carotids. 2, 2. Vertebrals. 
 3, 3. Right and left subclavians. 4, 4. 
 Eight and left superior intercostals. 5. 
 Left aortic arch, which remains perma- 
 nent. 6. Eight aortic arch, which dis- 
 appears. 
 
 The two ascending arterial trunks on the anterior part of the 
 neck, from which the cervical arches are given oft", become con- 
 verted into the carotids. (Fig 288, i, i.) The fifth, or uppermost 
 cervical arch, remains at the base of the brain as the inosculation, 
 through the circle of Willis, between the internal carotids and the 
 basilar artery, which is produced by the union of the two verte- 
 brals. The next, or fourth cervical arch, may be recognized in an 
 inosculation which is said to be very constant between the superior 
 thyroid arteries, branches of the carotids, and the inferior thyroids, 
 which come from the subclavians at nearly the same point from 
 which the vertebrals are given off". The next, or third cervical arch 
 remains on each side, as the subclavian artery (3, 3). This vessel, 
 though at first a mere branch of communication between the caro- 
 tid and the vertebral, has now increased in size to such an extent, 
 that it has become the principal trunk, from which the vertebral 
 
572 DEVELOPMENT OF THE CIECULATORY APPARATUS. 
 
 itself is given off as a small branch. Immediately below this point 
 of intersection, also, the vertebral artery diminishes very much in 
 its relative size, loses its connection with the abdominal aorta, and 
 supplies only the first two intercostal spaces, under the name of the 
 superior intercostal artery (4, 4). The second cervical arch becomes 
 altered in a very different manner on the two opposite sides. On 
 the left side, it becomes enormously enlarged, so as to give off, as 
 secondary branches, all the other arterial trunks which have been 
 described, and is converted in this manner into the arch of the 
 aorta (5). On the right side, however, the corresponding arch (e), 
 becomes smaller and smaller, and at last altogether disappears; so 
 that, finally, we have only a single aortic arch, projecting to the 
 left of the median line, and continuous with the thoracic and abdo- 
 minal aorta. 
 
 The first cervical arch remains during fcetal life upon the right 
 side, as the " ductus arteriosus," presently to be described. In the 
 adult condition, however, it has disappeared equally upon the right 
 and left sides. In this way the permanent condition of the arterial 
 circulation is gradually established in the upper part of the body. 
 
 Corresponding changes take place, however, during the same 
 time, in the lower part of the body. Here the abdominal aorta 
 runs undivided, upon the median line, quite to the end of the 
 spinal column; giving off on each side successive lateral branches, 
 which supply the intestine and the parietes of the body. When 
 the allantois begins to be developed, two of these lateral branches 
 accompany it, and become consequently the umbilical arteries. 
 These two vessels increase so rapidly in size, that they soon appear 
 as divisions of the aortic trunk ; while the original continuation of 
 this trunk, running to the end of the spinal column, appears only 
 as a small branch given off' at the point of bifurcation. When the 
 lower limbs begin to be developed, they are supplied by two small 
 branches, given off" from the umbilical arteries near their origin. 
 
 Up to this time the pelvis and posterior extremities are but 
 slightly developed. Subsequently, however, they grow more 
 rapidly, in proportion to the rest of the body, and the arteries 
 which supply them increase in a corresponding manner. That 
 portion of the umbilical arteries, lying between the bifurcation of 
 the aorta and the origin of the branches going to the lower ex- 
 tremities, becomes the common iliacs, which in their turn afterward 
 divide into the umbilical arteries proper, and the femorals. Sub- 
 sequently, by the continued growth of the pelvis and lower 
 
DEVELOPMENT OF THE VENOUS SYSTEM. 
 
 573 
 
 extremities, the relative size of their vessels is still further in- 
 creased ; and at last the arterial system in this part of the body 
 assumes the arrangement which belongs to the latter periods of 
 gestation. The aorta divides, as before, into the two common iliacs. 
 These also divide into the external iliacs, supplying the lower ex- 
 tremities, and the internal iliacs, supplying the pelvis; and this 
 division is so placed that the umbilical or hypogastric arteries arise 
 from the internal iliacs, of which they now appear to be secondary 
 branches. 
 
 After the birth of the foetus and the separation of the placenta, 
 the hypogastric arteries become partially atrophied, and are con- 
 verted, in the adult condition, into solid, rounded cords, running 
 upward toward the umbilicus. Their lower portion, however, 
 remains pervious, and gives off arteries supplying the urinary 
 bladder. The obliterated hypogastric arteries, therefore, the rem- 
 nants of the original umbilical or allantoic arteries, run upward 
 from the internal iliacs along the sides of the urinary bladder, which 
 is the remnant of the original allantois itself. The terminal con- 
 tinuation of the original abdominal aorta, is the arteria sacra media, 
 which, in the adult, runs downward on the anterior surface of the 
 sacrum, supplying branches to the rectum and the anterior sacral 
 nerves. 
 
 Development of the Venous System. — According 
 to the observations of M. Coste, the venous system 
 at first presents the same simplicity and symmetry 
 with the arterial. The principal veins of the 
 body consist of two long venous trunks, the ver- 
 iehral veins (Fig. 289), which run along the sides 
 of the spinal column, parallel with the vertebral 
 arteries. They receive in succession all the inter- 
 costal veins, and empty into the heart by two 
 lateral trunks of equal size, the canals of Cuvier. 
 When the inferior extremities become developed, 
 their two veins, returning from below, join the 
 vertebral veins near the posterior portion of the 
 body ; and, crossing them, afterward unite with 
 each other, thus constituting another vein of new 
 formation (Fig. 240, a), which runs upward a little EariyconaitionofVK- 
 to the right of the median line, and empties by ';>-o^s s^s^m; show- 
 
 ^ ' i- tJ mg the vertebral veins 
 
 itself into the lower extremity of the heart. The emptying into the heart 
 
 . ^ ^ -I r 1 • T J.^ ■ n ^7 two lateral trunks, 
 
 two branches, by means o± which the veins of the "eauaisof cuvier." 
 
 Fig 239. 
 
574 DEVELOPMENT OF THE CIRCULATORY APPARATUS. 
 
 Fig. 240. 
 
 Venous System far- 
 ther advanced, showing 
 formation of iliac and sub- 
 clavian veins. — a. Vein of 
 new formation, which be- 
 comes the inferior vena 
 cava. ft. Transverse branch 
 of new formation, which 
 afterward becomes the left 
 vena innominata. 
 
 Fig. 241. 
 
 Further development of 
 the Venous System — 
 The vertebral veins are 
 much diminished in size, 
 and the canal of Cuvier, on 
 the left side, is gradually- 
 disappearing, c. Trans- 
 verse branch of new forma- 
 tion, which is to become 
 the vena azygos minor. 
 
 the lower extremities thus unite, become after- 
 ward, by enlargement, the common iliac veins; 
 while the single trunk (a) resulting from their 
 union becomes the vena cava inferior. Subse- 
 quently, the vena cava inferior becomes very 
 much larger than the vertebral veins ; and its 
 two branches of bifurcation are afterward re- 
 presented by the two iliacs. 
 
 Above the level of the heart, the vertebral 
 and intercostal veins retain their relative size 
 until the development of the superior extremi- 
 ties has commenced. Then two of the inter- 
 costal veins increase in diameter (Fig. 240), and 
 become converted into the right and left sub- 
 clavians ; while those portions of the vertebral 
 veins situated above the subclavians become 
 the right and left jugulars. Just below the 
 junction of the jugulars with the subclavians, 
 a small branch of communication now appears 
 between the two vertebrals (Fig. 240, 6), pass- 
 ing over from left to right, and emptying into 
 the right vertebral vein a little above the level 
 of the heart ; so that a part of the blood coming 
 from the left side of the head, and the left upper 
 extremity, still passes down the left vertebral 
 vein to the heart upon its own side, while a part 
 crosses over by the communicating branch (6), 
 and is finally conveyed to the heart by the 
 right descending vertebral. Soon afterward, this 
 branch of communication enlarges so rapidly 
 that it preponderates altogether over the left 
 superior vertebral vein, from which it ori- 
 ginated (Fig. 241), and, serving then to convey 
 all the blood coming from the left side of the 
 head and left upper extremity over to the right 
 side above the heart, it becomes the left vena 
 innominata. 
 
 On the left side, that portion of the superior 
 vertebral vein, which is below the subclavian, 
 remains as a small branch of the vena innomi 
 nata, receiving the six or seven upper intercostal 
 
DEVELOPMENT OF THE VENOUS SYSTEM. 
 
 575 
 
 Fig. 242. 
 
 veins; while on the right side it becomes excessively enlarged, 
 receiving the blood of both jugulars and both subclavians, and is 
 converted into the vena cava superior. 
 
 The left canal of Cuvier, by which the left vertebral vein at first 
 communicates with the heart, subsequently becomes atrophied and 
 disappears; while on the right side it becomes excessively enlarged, 
 and forms the lower extremity of the vena cava superior. 
 
 The superior and inferior venae cavae, accordingly, do not cor- 
 respond with each other so far as regards their 
 mode of origin, and are not to be regarded as 
 analogous veins. For the superior vena cava 
 is one of the original vertebral veins ; while 
 the inferior vena cava is a totally distinct vein, 
 of new formation, resulting from the union of 
 the two lateral trunks coming from the infe- 
 rior extremities. 
 
 The remainder of the vertebral veins finally 
 assume the condition shown in Fig. 242, which 
 is the complete or adult form of the venous 
 circulation. At the lower part of the abdomen, 
 the vertebral veins send inward small trans- 
 verse branches, which communicate with the 
 vena cava inferior, between the points at which 
 they receive the intercostal veins. These 
 branches of communication, by increasing in 
 size, become the lumbar veins (7), which, in the 
 adult condition, communicate with each other 
 by arched branches, a short distance to the side 
 of the vena cava. Above the level of the 
 lumbar arches, the vertebral veins retain their 
 
 .5. Vena cava inferior. 6, 6. 
 
 original direction. .That upon the right side niac veins v. Lumbar veins, 
 still receives all the right intercostal veins, and '; ^'''"^ ■''''^'' ""'"'Z' J' 
 
 o ' Vena azygos minor. 10. su- 
 
 becomes the vena azyjos major (s). It also perior intercostal vein. 
 receives a small branch of communication from 
 its fellow of the left side (Fig. 24.1, c), and this branch soon enlarges 
 to such an extent as to bring over to the vena azygos major all the 
 blood of the five or six lower intercostal veins of the left side, 
 becoming, in this way, the vena azygos minor {9). The six or seven 
 upper intercostal veins on the left side still empty, as before, into 
 their own vertebral vein (10), which, joining the left vena innomi- 
 nata above, is known as the superior intercostal vein. The left canal 
 
 Adult condition of Ve- 
 xors System. — 1. Riglit 
 auricle of heart. 2. Vena 
 cava superior. 3, 3. Jugular 
 veins. 4,1:. Subclavian veins. 
 
576 DEVELOPMENT OF THE CIECULATORY APPARATUS. 
 
 of Cuvier lias by this time entirely disappeared; so that all the 
 venous blood now enters the heart by the superior or the inferior 
 vena cava. But the original vertebral veins are still continuous 
 throughout, though very much diminished in size at certain points; 
 since both the greater and lesser azygous veins inosculate below 
 with the superior lumbar veins, and the superior intercostal vein 
 also inosculates below with the lesser azygous, just before it passes 
 over to the right side. 
 
 There are still two parts of the circulatory apparatus, the deve- 
 lopment of which presents peculiarities sufficiently important to 
 be described by themselves. These are, first, the liver and the 
 ductus venosus, and secondly, the heart, with the ductus arteriosus. 
 Development of the Hepatic Circulation and the Ductvs Venosus. — 
 The liver appears at a very early period in the upper part of the 
 abdomen, as a mass of glandular and vascular tissue, which is deve- 
 loped around the upper portion of the om- 
 Fig. 243. phalo-rnesenteric vein, just below its termi- 
 
 nation in the heart. (Fig. 243.) As soon as 
 the organ has attained a considerable size, 
 the omphalo-mesenteric vein (i) breaks up in 
 its interior into a capillary plexus, the vessels 
 of which unite again into venous trunks, and 
 so convey the blood finally to the heart. 
 The omphalo-mesenteric vein below the liver 
 Early form of Hepatic then hecomes the portal veiu ; while above tiie 
 ciKccLATioN. 1 ompha- ^. ^^^ between that organ and the heart, 
 
 lo mesenteric vein. 2. Hepa- ' o ' 
 
 tic vein. 3. Heart. Tiiedotted [{, rcccivcs the uamc of the hcpatic Vein (2). 
 
 line shows the situation of „, ,. t i • . .1 • . • v i 
 
 the fnture umbilical vein. The hvcr, accordiugly, is at this time supplied 
 with blood entirely by the portal vein, com- 
 ing from the umbilical vesicle and the intestine; and all the blood 
 derived from this source must pass through the hepatic circulation 
 before reaching the venous extremity of the heart. 
 
 But soon afterward the allantois makes its appearance, and be- 
 comes rapidly developed into the placenta ; and the umbilical vein 
 comino- from it joins the omphalo-mesenteric vein in the substance 
 of the liver, and takes part in the formation of the hepatic capillary 
 plexus. As the umbilical vesicle, however, becomes atrophied, and 
 the intestine also remains inactive, while the placenta increases in 
 size and in functional importance, a time soon arrives when the 
 liver receives more blood by the umbilical vein than by the portal 
 vein. (Fig. 244.) The umbilical vein then passes into the liver at 
 
DEVELOPMENT OF THE HEPATIC CIRCULATION. 
 
 577 
 
 Hepatic CiRCULATioif 
 further advanced. — 1. Portal vein. 
 2. Umbilical vein. 3. Hepatic 
 vein. 
 
 the longitudinal fissure, and supplies the left lobe entirely with its 
 own branches. To the right it sends off a large branch of com- 
 munication, which opens into the portal vein, and partially supplies 
 the right lobe witb umbilical blood. The liver is thus supplied 
 with blood from two different sources, the 
 most abundant of which is the umbilical 
 vein ; and all the blood entering the liver 
 circulates, as before, through its capillary 
 vessels. 
 
 But we have already seen that the liver 
 is much larger in proportion to the entire 
 body at an early period of foetal life than 
 in the later months. In the foetal pig, 
 when very young, it amounts to nearly 
 twelve per cent, of the weight of the whole 
 body; but before birth it diminishes to 
 seven, six, and even three or four per cent. 
 
 For some time, therefore, previous to birth, there is mucb more 
 blood returned from the placenta than is required for the capillary 
 circulation of the liver. Accordingly, a vascular duct or canal is 
 formed in its interior, by which a portion of the placental blood is 
 carried directly through the organ, 
 and conveyed to the heart Avithout 
 having passed through the hepatic 
 capillaries. This duct is called the 
 Ductus venosus. 
 
 The ductus venosus is formed by a 
 gradual dilatation of one of the he- 
 patic capillaries at (s) (Fig. 245), 
 which, enlarging excessively, be- 
 comes at last converted into a wide 
 canal, or branch of communication, 
 passing directly from the umbilical 
 vein below to tlie hepatic vein above. 
 The circulation through the liver, 
 thus established, is as follows : A 
 certain quantity of venous blood still 
 enters through the portal vein (i), 
 and circulates in a part of the capil- 
 lary system of the right lobe. The umbilical vein (2), bringing a 
 much larger quantity of blood, enters the liver also, a little to the 
 37 
 
 Hepatic CiRCDLATioN during lat- 
 ter part of foetal life. — 1. Portal vein. 2. 
 Umbilical vein. 3. Left branch of umbili- 
 cal vein. 4. Right branch of umbilical 
 vein. 5. Ductus venosus. 6. Hepatic 
 vein. 
 
578 DEVELOPMENT OF THE CIRCULATORY APPARATUS. 
 
 left, and the blood which it contains divides into three principal 
 streams. One of them passes through the left branch (3) into the 
 capillaries of the left lobe ; another turns oft' through the right 
 branch (4), and, joining the blood of the portal vein, circulates 
 through the capillaries of the right lobe ; while the third passes 
 directly onward through the venous duet (5), and reaches the he- 
 patic vein without having passed through any part of the capillary 
 plexus. 
 
 This condition of the hepatic circulation continues until birth. 
 At that time, two important changes tai^e place. First, the pla- 
 cental circulation is altogether cut off; and secondly, a much larger 
 quantity of blood than before begins to circulate through the lungs 
 and the intestine. The superabundance of blood, previously coming 
 from the placenta, is now diverted into the lungs ; while the intes- 
 tinal canal, entering upon the active performance of its functions, 
 becomes the sole source of supply for the hepatic venous blood. 
 The following changes, therefore, take place at birth in the vessels 
 of the liver. (Fig. 246.) First, the umbilical vein shrivels and 
 becomes converted into a solid rounded cord (2). This cord may 
 be seen, in the adult condition, running from the internal surface of 
 the abdominal walls, at the umbilicus, to the longitudinal fissure of 
 
 the liver. It is then known under the 
 name of the round ligament. Secondly, 
 the ductus venosus also becomes ob- 
 literated, and converted into a fibrous 
 cord. Thirdly, the blood entering the 
 liver by the portal vein ( i ), passes off 
 by its right branch, as before, to the 
 right lobe. But in the branch (4), the 
 course of the blood is reversed. This 
 was formerly the right branch of the 
 umbilical vein, its blood passing in a 
 direction from left to right. It now 
 becomes the left branch of the portal 
 vein ; and its blood passes from right 
 to left, to be distributed to the capil- 
 laries of the left lobe. 
 
 According to Dr. Guy, the umbili- 
 cal vein is completely closed at the 
 end of the fifth day after birth. 
 Development of the Hearty and the Ductus Arteriosus. — When the 
 
 Yxs.. 246. 
 
 Adult form of Hepatic Ciuccla- 
 TION. — 1. Portal veiu. 2. Obliterated 
 umbilical vein, forming the round liga 
 ment ; the continuation of the dotted 
 lines through the liver shoves the situa- 
 tion of the obliterated ductus venosus. 
 3. Hepatic vein. 4. Left branch of portal 
 vein. 
 
DEVELOPMENT OF THE HEART. 
 
 579 
 
 embryonic circulation is first established, the heart is a simple tubu- 
 lar sac (Fig. 247), receiving the veins at its lower extremity, and 
 giving off' the arterial trunks at its upper extremity. By the pro- 
 gress of its growth, it soon becomes twisted upon itself; so that the 
 entrance of the veins, and the exit of the arteries, come to be placed 
 more nearly upon the same horizontal level (Fig. 248) ; but the 
 entrance of the veins (i) is behind and a little below, while the exit 
 of the arteries (2) is in front and a little above. The heart is, at 
 this time, a simple twisted tube; and the blood passes through it 
 in a single continuous stream, turning upon itself at the point of 
 curvature, and passing directly out by the arterial orifice. 
 
 Fig. 247. 
 
 2 
 
 Earliest form of F(etal 
 Heart. — 1. venous ex- 
 tremity. 2. Arterial ex- 
 tremity. 
 
 Fis. 248. 
 
 FffiTAL Heart, twi.sted 
 upon itself. — 1. Venous ex- 
 tremity. 2. Arterial ex- 
 tremitv. 
 
 FfKfAL Heart, divided 
 into right and left cavities. — 
 1. Venous extremity. 2. 
 Arterial extremity. 3, 3. 
 Pulmonary branches. 
 
 Soon afterward, this single cardiac tube is divided into two paral- 
 lel tubes, right and left, by a longitudinal partition, which grows 
 from the inner surface of its walls and follows the twisted course 
 of the organ itself. (Fig. 249.) This partition, which is indicated 
 in the figure by a dotted, line, extends a short distance into the 
 commencement of the primitive arterial trunk, dividing it into two 
 lateral halves, one of which is in communication with the right side 
 of the heart, the other with the left. 
 
 About the same time, the pulmonary branches (3,3) are given 
 off" from each side of the arterial trunk near its origin ; and the 
 longitudinal partition, above spoken of, is so placed that both these 
 branches fall upon one side of it, and are both, consequently, given 
 off' from that division of the artery which is connected with the right 
 side of the heart. 
 
 Very soon a superficial line of demarcation, or furrow, shows 
 itself upon the external surface of the heart, corresponding in situa- 
 tion with the internal septum ; while at the root of the arterial 
 trunk, this furrow becomes much deeper, and finally the two lateral 
 portions of the vessel are separated from each other altogether, in 
 
580 DEVELOPMENT OF THE CIKCULATORY APPARATUS. 
 
 F(ETAL Heart still far- 
 ther developed. — 1. Aorta. 
 2. Pulmonary artery. 3, 3. 
 Pulmonary branches. 4. 
 Ductus arteriosus. 
 
 Fig. 250. the immediate neighborhood of the heart, 
 
 joining again, however, a short distance beyond 
 the origin of the pulmonary branches. (Fig. 
 250.) It then becomes evident that the left 
 lateral division of the arterial trunk is the 
 commencement of the aorta (i); while its right 
 lateral division is the trunk of the pulmonary 
 artery (2), giving off the right and left pulmo- 
 nary branches (3, 3), at a short distance from 
 its origin. That portion of the pulmonary 
 trunk (4) which is beyond the origin of the 
 pulmonary branches, and which communicates freely with the 
 aorta, is the Ductus arteriosus. 
 
 The ductus arteriosus is at first as large as the pulmonary trunk 
 itself; and nearly the whole of the blood, coming from the right 
 ventricle, passes directly onward through the arterial duct, and 
 enters the aorta without going to the lungs. But as the lungs 
 gradually become developed, they require a larger quantity of 
 blood for their nutrition, and the pulmonary branches increase in 
 proportion to the pulmonary trunk and the ductus arteriosus. At 
 the termination of foetal life, in the human subject, the ductus 
 arteriosus is about as large as either one of the pulmonary 
 branches; and a very considerable portion of the blood, therefore, 
 eoming from the right ventricle still passes onward to the aorta 
 without being distributed to the lungs. 
 
 But at the period of birth, the lungs enter upon the active per- 
 formance of the function of respiration, 
 and immediately require a much larger 
 supply of blood. The right and left 
 pulmonary branches then enlarge, so 
 as to become the two principal divis- 
 ions of the pulmonary trunk. (Fig. 251.) 
 The ductus arteriosus at the same time 
 becomes contracted and shrivelled to such 
 an extent that its cavity is obliterated ; 
 and it is finally converted into an im- 
 heabt of Infant, showing pcrvious, rouudcd cord, wliich remains 
 
 disappearance of arterial duct after yxn\i\ adult life, rUUniug frOm the poiut 
 birth.— 1. Aorta. 2. Pulmonary ar- p • r- i i 
 
 tery. 3, 3. Pulmonary branches. 4. of bifurcatiou of the pulmouary artery 
 
 Ductus arteriosus becoming oblite- ^^ ^^^ ^^^j^^ gj^^, ^f ^^iQ arch of the 
 rated. 
 
 Fig. 2^1. 
 
DEVELOPMENT OF THE HEART, 581 
 
 aorta. The obliteration of the arterial duct is complete, at latest, 
 by the tenth week after birth. (Gruy.) 
 
 The two auricles are separated from the two ventricles by hori- 
 zontal septa which grow from the internal surface of the cardiac 
 walls ; but these septa remaining incomplete, the auriculo-ventricu- 
 lar orifices continue pervious, and allow the free passage of the 
 blood from the auricles to the ventricles. 
 
 The interventricular septum, or that which separates the two 
 ventricles from each other, is completed at a very early date ; but 
 the interauricular septum, or that which is situated between the 
 two auricles, remains incomplete for a long time, being perforated 
 by an oval-shaped opening, the foram£n ovale, allowing, at this 
 situation, a free passage from the right to the left side of the heart. 
 The existence of the foramen ovale and of the ductus arteriosus 
 gives rise to a peculiar crossing of the streams of blood in passing 
 through the heart, which is characteristic of foetal life, and which 
 may be described as follows : — 
 
 It will be found upon examination that the two venae cavae, 
 superior and inferior, do not open into the auricular sac on the 
 same plane or in the same direction ; for while the superior vena 
 cava is situated anteriorly, and is directed downward and forward, 
 the inferior is situated quite posteriorly, and passes into the auricle 
 in a direction from right to left, and nearly transverse to the axis 
 of the heart. A nearly vertical curtain or valve at the same time 
 hangs downward behind the orifice of the superior vena cava and 
 in front of the orifice of the inferior. This curtain is formed by 
 the lower edge of the septum of the auricles, which, as we have 
 before stated, is incomplete at this age, and which terminates 
 inferiorly and toward the right in a crescentic border, leaving at 
 that part an oval opening, the foramen ovale. The stream of blood, 
 coming from the superior vena cava, falls accordingly in front of 
 this curtain, and passes directly downward, through the auriculo- 
 ventricular orifice, into the right ventricle. But the inferior vena 
 cava, being situated farther back and directed transversely, opens, 
 properly speaking, not into the right auricle, but into the left ; for 
 its stream of blood, falling behind the curtain above mentioned, 
 passes across through the foramen ovale directly into the cavity of 
 the left auricle. This direction of the current of blood, coming 
 from the inferior vena cava, is further secured by a peculiar mem- 
 branous valve, which exists at this period, termed the Eustachian 
 
582 
 
 DEVELOPMENT OF THE CIRCULATORY APPARATUS. 
 
 valve. This valve, which is very thin and transparent (Fig. 252,/), 
 is attached to the anterior border of the orifice of the inferior vena 
 cava, and terminates by a crescentic edge, directed toward the left ; 
 
 the valve, in this way, standing 
 Fig. 252. as an incomplete membranous 
 
 partition between the cavity of 
 the inferior vena cava and that 
 of the right auricle. A bougie, 
 accordingly, placed in the in- 
 ferior vena cava, as shown in 
 Fig. 252, lies naturally quite 
 behind the Eustachian valve, 
 and passes directly through 
 the foramen ovale into the left 
 auricle. 
 
 The two streams of blood, 
 therefore, coming from the su- 
 perior and inferior venae cavse, 
 cross each other upon entering 
 the heart. This crossing of the 
 streams does not take place, 
 however, as it is sometimes 
 described, in the cavity of the 
 right auricle; but, owing to the 
 peculiar position and direction 
 of the two veins at this period, 
 witb regard to the septum of 
 the auricles, the stream coming from the superior vena cava enters 
 the right auricle exclusively, while that from the inferior passes 
 almost directly into the left auricle. 
 
 It will also be seen, by examining the positions of the aorta, pul- 
 monary artery, and ductus arteriosus, at this time, that the arteria 
 innominata, together with the left carotid and left subclavian, are 
 given off from the arch of the aorta, before its junction with the 
 ductus arteriosus, and this arrangement causes the blood of the two 
 venae cavse, not only to enter the heart in different directions, but 
 also to be distributed, after leaving the ventricles, to different parts 
 of the body. (Fig. 253 ) For the blood of the superior vena cava 
 passes through the right auricle downward into the right ventricle, 
 thence through the pulmonary artery and ductus arteriosus, into 
 the thoracic aorta, while the blood of the inferior vena cava, enter- 
 
 Heart of Human Fcetus, attlie end of the 
 sixth month ; from a specimen in tlie author's pos- 
 session. — a. Inferior vena cava. h. Superior vena 
 cava. c. Cavity of right auricle, laid open from 
 the front d. Appendix auricularis. e. Cavity of 
 right ventricle, also laid open. /. Eustachian valve. 
 The bougie, which is placed in the inferior vena 
 cava,, can be seen passing behind the Eustachian 
 valve, just below the point indicated by f, then 
 crossing behind the cavity of the right auricle, and 
 passing through the foramen ovale, to the left side 
 of the heart. 
 
DEVELOPMENT OF THE HEART. 
 
 583 
 
 Fisr. 253. 
 
 ing the left auricle, passes into the left ventricle, thence into the arch 
 of the aorta, and is distributed to the head and upper extremities, 
 before reaching the situation of the arterial duct. The two streams, 
 therefore, in passing through the heart, cross each other both behind 
 and in front. The venous blood, returning from the head and 
 upper extremities by the superior 
 vena cava, passes through the abdo- 
 minal aorta and the umbilical arte- 
 ries, to the lower part of the body, 
 and to the placenta; while that re- 
 turning from the placenta, by the 
 inferior vena cava, is distributed to 
 the head and upper extremities, 
 through the vessels given off from 
 the arch of the aorta. 
 
 This division of the streams of 
 blood, during a certain period of 
 foetal life, is so complete that Dr. 
 John Reid,^ on injecting the infe 
 rior vena cava with red, and the 
 superior with yellow, in a seven 
 months' human foetus, found that the red had passed through the 
 foramen ovale into the left auricle and ventricle and arch of the 
 aorta, and had filled the vessels of the head and upper extremities : 
 while the yellow had passed into the right ventricle, pulmonary 
 artery, ductus arteriosus, and thoracic aorta, with only a slight ad- 
 mixture of red at the posterior part of the right auricle. All the 
 branches of the thoracic and abdominal aorta were filled with yel- 
 low, while the whole of the red had passed to the upper part of the 
 body. 
 
 We have repeated the above experiment several times on the 
 foetal pig, when about one-half and three-quarters grown, first taking 
 the precaution to wash out the heart and large vessels with a wa- 
 tery injection, immediately after the removal of the foetus from the 
 body of the parent, and before the blood had been allowed to coagu- 
 late. The injections used were blue for the superior vena cava, 
 and yellow for the inferior. The two syringes were managed, at 
 the same time, by the right and left hands; their nozzles being 
 firmly held in place by the fingers of an assistant. When the 
 
 Diagram of CiRcaLATioN through 
 THE FcETAL HEART. — rt. Superior veaa 
 cava. 6. Inferior vena cava. c,c,c,o Arch 
 of aorta and its branches, d. Pulmonary 
 
 artery. 
 
 ' Edinburgh Medical and Surgical Journal, vol. xliii. 1835. 
 
584 DEVELOPMENT OF THE CIECULATORY APPARATUS. 
 
 points of the syringes were introduced into the veins, at equal dis- 
 tances from the heart, and the two injections made with equal force 
 and rapidity, it was found that the admixture of the colors which 
 took place was so slight, that at least nineteen-twentieths of the yellow 
 injection had passed into the left auricle, and nineteen-twentieths of 
 the blue into the right. The pulmonary artery and ductus arteriosus 
 contained a similar proportion of blue, and the arch of the aorta of 
 yellow. In the thoracic and abdominal aorta, however, contrary to 
 what was found by Dr. Eeid, there was always an admixture of the 
 two colors, generally in about equal proportions. This discrepancy 
 may be owing to the smaller size of the head and upper extremities, 
 in the pig, as compared with those of the human subject, which would 
 prevent their receiving all the blood coming from the left ventricle ; 
 or to some differences in the manipulations of these experiments, 
 in which it is not always easy to imitate exactly the force and ra- 
 pidity of the different currents of blood in the living foetus. The 
 above results, however, are such as to leave no doubt of the prin- 
 cipal fact, viz., that up to an advanced stage of foetal life, by far the 
 greater portion of the blood coming from the inferior vena cava 
 passes through the foramen ovale, into the left side of the heart ; 
 while by far the greater portion of that coming from the head and 
 upper extremities passes into the right side of the heart, and thence 
 outward by the pulmonary trunk and ductus arteriosus. Toward 
 the latter periods of gestation, this division of the venous currents 
 becomes less complete, owing to the three following causes: — 
 
 First, the lungs increasing in size, the two pulmonary arteries, 
 as well as the pulmonary veins, enlarge in proportion; and a greater 
 quantity of the blood, therefore, coming from the right ventricle, 
 instead of going onward through the ductus arteriosus, passes to 
 the lungs, and returning thence by the pulmonary veins to the left 
 auricle and ventricle, joins the stream passing out by the arch of 
 the aorta. 
 
 Secondly, the Eustachian valve diminishes in size. This valve, 
 which is very large and distinct at the end of the sixth month 
 (Fig. 252), subsequently becomes atrophied to such an extent that, 
 at the end of gestation, it has altogether disappeared, or is at least 
 reduced to the condition of a very narrow, almost imperceptible 
 membranous ridge, which can exert no influence on the direction of 
 the current of blood passing by it. Thus, the cavity of the supe- 
 rior vena cava, at its upper extremity, ceases to be separated from 
 
DEVELOPMENT OF THE HEART. 585 
 
 that of the right auricle; and a passage of blood from one to the 
 other may, therefore, more readily take place. 
 
 Thirdly, the foramen ovale becomes partially closed by a valve 
 which passes across its orifice from behind forward. This valve, 
 which begins to be formed at a very early period, is called the 
 valve of the foramen ovale. It consists of a thin, fibrous sheet, which 
 grows from the posterior surface of the auricular cavity, just to the 
 left of the foramen ovale, and projects into the left auricle, its free 
 edge presenting a thin crescentic border, and being attached, by its 
 two extremities, to the auricular septum upon the left side. This 
 valve does not at first interfere at all with the flow of blood from 
 right to left, since its edge hangs freely and loosely into the cavity 
 of the left auricle. It only opposes, therefore, during the early 
 periods, any accidental regurgitation from left to right. 
 
 But as gestation advances, while the walls of the heart con- 
 tinue to enlarge, and its cavities to expand in every direction, the 
 fibrous bundles, forming the valve, do not elongate in proportion. 
 The valve, accordingly, becomes drawn downward more and more 
 toward the foramen ovale. It thus comes in contact with the edges 
 of the interauricular septum, and unites with its substance; the 
 adhesion taking place first at the lower and posterior portion, and 
 proceeding gradually upward and forward, so as to make the pas- 
 sage, from the right auricle to the left, more and more oblique in 
 direction. 
 
 At the same time, an alteration takes place in the position of the 
 inferior vena cava. This vessel, which at first looked transversely 
 toward the foramen ovale, becomes directed more obliquely for- 
 ward ; so that, the Eustachian valve having mostly disappeared, a 
 part of the blood of the inferior vena cava enters the right auricle, 
 while the remainder still passes through the equally oblique open- 
 ing of the foramen ovale. 
 
 At the period of birth a change takes place, by which the 
 foramen ovale is completely occluded, and all the blood coming 
 through tiie inferior vena cava is turned into the right auricle. 
 
 This change depends upon the commencement of respiration. 
 A much larger quantity of blood than before is then sent to the 
 lungs, and of course returns from them to the left auricle. The 
 left auricle, being then completely filled wath the pulmonary blood, 
 no longer admits a free access from the right auricle through the 
 foramen ovale; and the valve of the foramen, pressed backward 
 more closely against the edges of the septum, becomes after a time 
 
586 
 
 DEVELOPMENT OF THE CIRCULATORY APPARATUS. 
 
 adherent throughout and obliterates the opening altogether. The 
 cutting off of the placental circulation diminishes at the same time 
 the quantity of blood arriving at the heart by the inferior vena 
 cava. It is evident, indeed, that the same quantity of blood which 
 previously returned from the placenta by the inferior cava, on the 
 right side of the auricular septum, now returns from the lungs, by 
 the pulmonary veins upon the left side of the same septum ; and it 
 is owing to all these circumstances combined, that while before birth 
 a portion of the blood always passed from the right auricle to the 
 left through the foramen ovale, no such passage takes place after 
 birth, since the pressure is then equal on both sides of the auricular 
 septum. 
 
 The foetal circulation, represented in Fig. 253, is then replaced 
 by the adult circulation, represented in Fig. 254. 
 
 Fig. 254. 
 
 Diagram of Adult Circulation throuuh the Heart — a, a. Superior and inferior venae 
 cav33. b. Right ventricle, c. Pulmonary artery, dividing into right and left branches, d. Pulmo- 
 nary vein. e. Left ventricle. /. Aorta. 
 
 That portion of the septum of the auricles, originally occupied 
 by the foramen ovale, is accordingly constituted, in the adult con- 
 dition, by the valve of the foramen ovale, whicb has become adhe- 
 rent to the edges of the septum. The auricular septum in the adult 
 heart is, therefore, thinner at this spot than elsewhere; and presents, 
 on the side of the right auricle, an oval depression, termed the fossa 
 
DEVELOPMENT OF THE HEART. 587 
 
 ovalis^ which indicates the site of the original foramen ovale. The 
 fossa ovalis is surrounded by a slightly raised ring, the annulus 
 ovalis, representing the curvilinear edge of the original auricular 
 septum. 
 
 The foramen ovale is sometimes completely obliterated within a 
 few daj^s after birth. It often, however, remains partially pervious 
 for several weeks or months. We have a specimen, taken from a 
 child of one year and nine months, in which the opening is still 
 very distinct; and it is not unfrequent to find a small apertare ex- 
 isting even in adult life. In these instances, however, though the 
 adhesion and solidification of the auricular septum is not complete, 
 no disturbance of the circulation results, and no admixture of 
 blood takes place between the right and left sides of the heart ; 
 since the passage through the auricular septum is always very 
 oblique in its direction, and its valvular arrangement prevents any 
 regurgitation from left to right, while the complete filling of the 
 left auricle with pulmonary blood, as above mentioned, equally 
 opposes any passage from right to left. 
 
588 DEVELOPMENT OF THE BODY AFTER BIRTH. 
 
 CHAPTER XVIII. 
 
 DEVELOPMENT OF THE BODY AFTER BIRTH. 
 
 The newly-born infant is still very far from having arrived at a 
 state of complete development. The changes which it has passed 
 through during intra-uterine life are not more marked than those 
 which are to follow during the periods of infancy, childhood, and 
 adolescence. The anatomy of the organs, both internal and ex- 
 ternal, their physiological functions, and even the morbid derange- 
 ments to which they are subject, continue to undergo gradual and 
 progressive alterations, throughout the entire course of subsequent 
 life. The history of development extends, properly speaking, from 
 the earliest organization of the embryonic tissues to the complete 
 formation of the adult body. The period of birth, accordingly, 
 marks only a single epoch in a constant series of changes, some of 
 which have preceded, while many others are to follow. 
 
 The weight of the newly-born infant is a little over six pounds. 
 The middle point of the body is nearly at the umbilicus, the head 
 and upper extremities being still very large, in proportion to the 
 lower extremities and pelvis. The abdomen is larger and the 
 chest smaller in proportion than in the adult. The lower extremi- 
 ties are curved inward, as in the foetal condition, so that the soles of 
 the feet look obliquely toward each other, instead of being directed 
 horizontally downward, as at a subsequent period. Both upper 
 and lower extremities are habitually curled upward and forward 
 over the chest and abdomen, and all the joints are constantly in a 
 semi-flexed position. 
 
 The process of respiration is very imperfectly performed for 
 some time after birth. The expansion of the pulmonary vesicles, 
 and the changes in the circulatory apparatus described in the pre- 
 ceding chapter, far from being sudden and instantaneous, are 
 always more or less gradual in their character, and require an 
 interval of several days for their completion. Respiration, indeed, 
 seems to be accomplished, during this period, to a considerable 
 
DEVELOPMENT OF THE BODY AFTER BIRTH. 589 
 
 extent through the skin, which is remarkably soft, vascular, and 
 ruddy in color. The animal heat is also less actively generated 
 than in the adult, and requires to be sustained by careful protec- 
 tion, and by contact with the body of the mother. The young 
 infant sleeps during the greater part of the time; and even when 
 awake there are but few manifestations of intelligence or percep- 
 tion. The special senses of sight and hearing are dull and inex- 
 citable, though their organs are perfectly formed ; and even 
 consciousness seems present only to a very limited extent. Volun- 
 tary motion and sensation are nearly absent ; and the almost con- 
 stant irregular movements of the limbs, observable at this time, 
 are evidently of a reflex or automatic character. Nearly all the 
 nervous phenomena, indeed, presented by the newly-born infant, 
 are of a similar nature. The motions of its hands and feet, the act 
 of suckling, and even its cries and the contortions of its face, are 
 reflex in their origin, and do not indicate the existence of any 
 active volition, or any distinct perception of external objects. 
 There is at first but little nervous connection established with the 
 external world, and the system is as yet almost exclusively occu- 
 pied with the functions of nutrition and respiration. 
 
 This preponderance of the simple reflex actions in the nervous 
 system of the infant, is observable even in the diseases to which it 
 is peculiarly subject for some years after birth. It is at this age 
 that convulsions from indigestion are of most frequent occurrence, 
 and even temporary strabismus and paralysis, resulting from the 
 same cause. It is well known to physicians, moreover, that the 
 effect of various drugs upon the infant is very different from that 
 which they exert upon the adult. Opium, for example, is very 
 much more active, in proportion to the dose, in the infant than in 
 the adult. Mercury, on the other hand, produces salivation with 
 greater difficulty in the former than in the latter. Blisters excite 
 more constitutional irritation in the young than in the old subject; 
 and antimony, when given to children, is proverbially uncertain 
 and dangerous in its operation. 
 
 The difference in the anatomy of the newly -born infant, and that 
 of the adult, may be represented, to a certain extent, by the fol- 
 lowing list, which gives the relative weight of the most important 
 internal organs at the period of birth and that of adult age; the 
 weight of the entire body being reckoned, in each case, as 1000. 
 The relative weight of the adult organs has been calculated from 
 
590 
 
 DEVELOPMENT OF THE BODY AFTER BIRTH. 
 
 the estimates of Cruveilhier, Solly, Wilson, &c,; that of the organs 
 in the foetus at term from our own observations. 
 
 
 
 
 FcETDS AT Term. 
 
 Adult. 
 
 Weight 
 
 of the entire body 
 
 . 1000.00 
 
 1000.00 
 
 
 " encephalon 
 
 
 . 148.00 
 
 23.00 
 
 
 " liver . 
 
 
 37.00 
 
 29.00 
 
 
 " heart . 
 
 
 7.77 
 
 4.17 
 
 
 " kidneys 
 
 
 6.00 
 
 4.00 
 
 
 " renal cap ules 
 
 
 l.t)3 
 
 0.13 
 
 
 " thyroid gland 
 
 
 0.60 
 
 0.51 
 
 
 " thymus gland 
 
 
 3.00 
 
 0.00 
 
 will be observed that most of the internal orcra 
 
 ns dimini 
 
 relative size after birth, owing principally to the increased develop- 
 ment of the osseous and muscular S3'-stems, both of which are in a 
 very imperfect condition throughout intra-uterine life, but which 
 come into activity during childhood and youth. 
 
 Within the first day after birth the remains of the umbilical 
 cord begin to wither, and become completely desiccated by about 
 the third day. A superficial ulceration then takes place about the 
 point of its attachment, and it is separated and thrown off within 
 the first week. After the separation of the cord, the umbilicus 
 becomes completely cicatrized by the tenth or twelfth day after 
 birth. (Guy.) 
 
 An exfoliation and renovation of the cuticle also take place 
 over the whole body soon after the birth. According to Kolliker, 
 the eyelashes, and probably all the hairs of the body and head, are 
 thrown off and replaced by new ones, within the first year. 
 
 The teeth in the newly-born infant are but partially developed, 
 and are still inclosed in their follicles, and concealed beneath the 
 gums. They are twenty in number; viz., two incisors, one canine, 
 and two molars, on each side of each jaw. At birth there is a thin 
 layer of dentine and enamel covering their upper surfaces, but 
 the body of the tooth and its fangs are formed subsequently by 
 progressive elongation and ossification of the tooth-pulp. The 
 fully-formed teeth emerge from the gums in the following order. 
 The central incisors in the seventh month after birth ; the lateral 
 incisors in the eighth month; the anterior molars at the end of the 
 first year; the canines at a year and a half; and the second molars 
 at two years (Kolliker). The eruption of the teeth in the lower 
 jaw generally precedes by a short time that of the corresponding 
 teeth in the upper. 
 
 During the seventh year a change begins to take place by which 
 
DEVELOPMENT OF THE BODY AFTER BIRTH. 591 
 
 the first set of teeth are thrown oft' and replaced by a second or 
 permanent set, differing in number, size, and shape from those 
 which preceded. The anterior permanent molar first shows itself 
 just behind the posterior temporary molar, on each side. This 
 happens at about six and a half years after birth. At the end of 
 the seventh year the middle incisors are thrown oft" and replaced 
 by corresponding permanent teeth, of larger size. At the eighth 
 year a similar exchange takes place in the lateral incisors. In the 
 ninth and tenth years, the anterior and second molars are replaced 
 by the anterior and second permanent bicuspids. In the twelfth 
 year, the canine teeth are changed. In the thirteenth year, the 
 second permanent molars show themselves; and from the seven- 
 teenth to the twenty-first year, the third molars, or " wisdom teeth," 
 emerge from the gums, at the posterior extremities of the dental 
 arch. (Wilson.) The jaw, therefore, in the adult condition, contains 
 three teeth on each side more than in childhood, making in all 
 thirty-two permanent teeth ; viz., on each side, above and below, 
 two incisors, one canine, two bicuspids, and three permanent 
 molars. 
 
 The entire generative apparatus, which is still altogether inactive 
 at birth, begins to enter upon a condition of functional activity 
 from the fifteenth to the twentieth year. The entire configuration 
 of the body alters in a striking manner at this period, and the dis- 
 tinction between the two sexes becomes more complete and well 
 marked. The beard is developed in the male ; and in the female 
 the breasts assume the size and form characteristic of the condition 
 of puberty. The voice, which is shrill and sharp in infancy and 
 childhood, becomes deeper in tone, and the countenance assumes a 
 more sedate and serious expression. After this period, the mus- 
 cular system increases still further in size and strength, and the 
 consolidation of the skeleton also continues; the bony union of its 
 various parts not being entirely accomplished until the twenty-fifth 
 or thirtieth year. Finally, all the different organs of the body arrive 
 at the adult condition, and the entire process of development is 
 then complete. 
 
INDEX. 
 
 Absorption, 128 
 
 by bloodvessels, 131 
 
 by lacteals, 133 
 
 of fat, 137 
 
 of oxygen in respiration, 207 
 
 by egg during incubation, 508 
 
 of calcareous matter by allantois, 
 508 
 Absorbent glands, 134 
 
 vessels, 133-136 
 Acid, carbonic, 206-217 
 
 lactic, in gastric juice, 107 
 
 in souring milk, 277 
 
 glyko-cliolic, 146 
 
 tauro-cholic, 147 
 
 pneumic, 211 
 
 uric, 288-296 
 
 oxalic, in urine, 301 
 Acid fermentation of urine, 300 
 Acidity, of gastric juice, cause of, 107 
 
 of urine, 295 
 Acini, of liver, 279-280 
 Adipose vesicles, 58 
 
 digestion of, 126-127 
 Adult circulation, 570 
 
 establishment of, 585 
 Aerial respiration, 198-200 
 Age, influence of, on exhalation of car- 
 bonic acid, 215 
 
 on comparative weight of organs, 590 
 Air, alterations of, in respiration, 206 
 
 circulation of, in lungs, 204 
 Air-cells of lungs, 200 
 Air-chamber, in fowl's egg, 454 
 Albumen, 68 
 
 of the blood, 189 
 
 in saliva, 93 
 
 in milk, 276 
 
 of the egg, how produced, 453 
 
 its liquefaction and absorption dur- 
 ing development of foetus, 504-506 
 Albuminoid substances, 63 
 
 digestion of, 110 
 Albuminose, 110 
 
 interference with Trommer's test, 
 111 
 
 with action of iodine and starch, 112 
 
 Alimentary canal, in different animals, 
 84-88 
 
 development of, 546. 
 Alkalies, effect of, on urine, 296 
 Alkaline chlorides, 39-42 
 
 phosphates, 45 
 
 carbonates, 44-45 
 Alkaline fermentation of urine, 302 
 Alkalescence of blood, due to carbonates, 
 
 44 
 Allantois, 501 
 
 formation of, 503 
 
 in fowl's egg, 506 
 
 function of, 507 
 
 in foetal pig, 524 
 Alligator, brain of, 322 
 Amnion, 501, 
 
 formation of, 502 
 
 enlargement of, during latter part of 
 pregnancy, 532 
 
 contact with chorion, 533 
 Amniotic folds, 502 
 Amniotic fluid, 532 
 
 its use, 533 
 
 contains sugar at a certain period,. 
 551 
 Amniotic umbilicus, 502 
 Analysis, of animal fluids, 32-33 
 
 of milk, 80 
 
 of wheat flour, 80 
 
 of oatmeal, 80 
 
 of eggs, 81 
 
 of meat, 81 
 
 of saliva, 92 
 
 of gastric juice, 107 
 
 of pancreatic juice, 123 
 
 of bile, 142 
 
 of blood-globules, 183 
 
 of blood-plasma, 188 
 
 of mucus, 269 
 
 of sebaceous matter, 270 
 
 of perspiration, 272 
 
 of milk, 275 
 
 of butter, 277 
 
 of urine, 294 
 Anoral and Gavakret, production of 
 carbonic acid in respiration, 214 
 
 38 
 
594 
 
 INDEX. 
 
 Animal functions, 27 
 Animal heat, 218 
 
 in different species, 220 
 
 mode of generation, 222-228 
 
 influenced by local causes, 226 
 
 in diffei'ent organs, 227 
 
 increase of, after section of sympa- 
 thetic nerve, 421-422 
 Animal and vegetable parasites, 434 
 Animalcules, infusorial, 431 
 
 mode of production, 432 
 Annulus ovalis, 586 
 Anterior columns of spinal cord, 321 
 
 their excitability, 343 
 Aorta, action of, 247 
 
 development of, 571 
 Aplysia, nervous system of, 315 
 Appetite, disturbed by anxiety, &c., 117 
 
 necessary to digestion of food, 118 
 Aquatic respiration, 197-198 
 Area pellucida, 492 
 
 vasculosa, 505-567 
 Arch of aorta, formation of, 571-572 
 Arches, cervical, 570 
 
 transformation of, 571 
 Arteries, 246 
 
 motion of blood in, 247 
 
 pulsation of, 248 
 
 elasticity of, 246, 249 
 
 rapidity of circulation in, 250-251 
 
 omphalo-mesenteric, 567 
 
 vertebral, 570 
 
 umbilical, 570 
 Arterial system, development of, 570- 
 
 579 
 Articulata, nervous system of, 316 
 
 reflex action in, 317 
 Articulation of tapeworm, 443 
 Arytenoid cartilages, 205 
 
 movements of, 206 
 Assimilation, 265 
 
 destructive, 282 
 Auricle, single, of fish, 230 
 
 double, of reptiles, birds, and mam- 
 malians, 231-232 
 
 contraction of, 245 
 Auriculo-ventricular valves, action of, 
 
 234 
 Auditory nerves, 386 
 Axis-cylinder, of nervous filaments, 
 
 308-310 
 Aztec children, 366 
 Azygous veins, formation of, 575 
 
 Beaumont, Dr., experiments on Alexis 
 
 St. Martin, 103-114 
 Beknard, on efi'ect of dividing Steno's 
 duct, 99 
 on digestion of fat in intestine, 123 
 on formation of liver-sugar, 166, 167, 
 
 168 
 on decomposition of bicarbonates in 
 lung, 212 
 
 Bernard, on temperature of blood in dif- 
 ferent organs, 2"i7 
 Bidder and Schmidt, on daily quantity 
 of bile, 153 
 
 on effect of excluding bile from in- 
 testine, 160 
 
 on reabsorption of bile, 161 
 Bile, 141 
 
 composition of, 142 
 
 tests for, 150 
 
 daily quantity of, 153 
 
 functions of, 158 
 
 reabsorption, 161 
 
 mode of secretion, 278 
 Biliary salts, 143 
 
 of human bile, 149 
 Biliverdine, 71, 142 
 
 tests for, 150 
 
 passage into the urine, 299 
 Blastodermic membrane, 490 
 Blood, 178 
 
 red globules of, 179 
 
 white globules, 185 
 
 plasma, 188 
 
 coagulation of, 190 
 
 bully coat, 195 
 
 entire quantity of, 196 
 
 alterations of, in respiration, 207 
 
 temperature of, 219 
 
 in different organs, 227 
 
 circulation of, 229 
 
 through the heart, 235 
 through the arteries, 246 
 through the veins, 252 
 through the capillaries, 255 
 Boussingault, on chloride of sodium in 
 food, 41 
 
 on internal production of fat, 61 
 Brain, 357 
 
 of alligator, 322 
 
 of rabbit, 323 
 
 human, 326 
 
 remarkable cases of injury to, 360 
 
 size of, in different races, 364 
 in idiots, 366 
 
 development of, 540-541 
 Branchiae, 197 
 
 of meno-branchus, 198 
 Broad ligaments, formation of, 563 
 Bronchi, division of, 200 
 
 ciliary motion in, 204 
 Brunner's glands, 120 
 Buffy coat of the blood, 195 
 Butter, 276 
 
 composition of, 277 
 
 condition in milk, 59, 277 
 Butyrine, 277 
 
 Canals of Cuvier, 573 
 Capillaries, 255 
 
 their inosculation, 256 
 
 motion of, blood in, 257 
 Capillary circulation, 256 
 
INDEX. 
 
 595 
 
 Capillary circiUation, causes of, 258 
 
 how modified by inflammation, 259 
 rapidity of, 260 
 
 peculiarities of, in diflferent parts, 
 262, 264 
 Caput coli, formation of, 547 
 Carbonic acid, in the breath, 206 
 
 proportion of, to oxygen absorbed, 
 
 207 
 in the blood, 208 
 origin of, in lungs, 211 
 in the blood, 212 
 in the tissues, 212 
 mode of production, 213 
 daily quantity of, 214 
 variations of, 215 
 exhaled by skin, 217 
 
 by egg, during incubation, 508 
 absorbed by vegetables, 225 
 Carbonate of lime, 44 
 of soda, 44 
 of potass, 45 
 
 of ammonia, in putrefying urine, 302 
 Cardiac circulation, in foetus, 583 
 
 in adult, 586 
 Carnivorous animals, respiration of, 18, 
 207 
 urine of, 287, 289 
 Cartilagine, 70 
 Caseine, 68 
 Cat, secretion of bile in, 154 
 
 closure of eyelids, after division of 
 sympathetic, 423 
 Catalytic action, 66 
 of pepsin, 110 
 Centipede, nervous system of, 316 
 Centre, nervous, definition of, 313 
 Cerebrum, 359. See Hemispheres. 
 Cerebral ganglia, 322-357. See Hemi- 
 spheres. 
 Cerebellum, 370 
 
 effects of injury to, 371 
 removal of, 371, 372 
 function of, 370-373 
 development of, 540-541 
 Cerebro-spinal system, 318-319 
 
 development of, 539 
 Cervix uteri, 456 
 in fffitus, 564 
 Cervical arches, 570 
 
 transformation of, 571 
 Changes, in egg, while passing through 
 oviduct, 450, 453, 488 
 in hepatic circulation, at birth, 578 
 in comparative size of organs, after 
 birth, 590 
 Chick, developmfent of, 504-509 
 Children, Aztec, 366 
 Chloride of sodium, 39 
 
 its proportion in the animal tissues 
 
 and fluids, 40 
 importance of, in the food, 41 
 mode of discharge from the body, 41 
 
 Chloride of sodium, partial decomposi- 
 tion of, in the body, 42 
 Chloride of potassium, 42 
 Cholesterine, 142 
 Chorda dorsalis, 493 
 Chordse vocales, movement of, in respi- 
 ration, 205 
 action of, in the production of vocal 
 
 sounds, 403 
 obstruction of glottis by, after divi- 
 sion of pneumogastric, 405 
 Chorion, formation of, 510 
 villosities of, 512 
 source of vascularity of, 513 
 union with decidua, 521 
 Chyle, 121-133 
 
 in lacteals, 136 
 absorption of, 137 
 
 by intestinal epithelium, 138 
 in blood, 139 
 Ciliary motion, in bronchi, 204 
 
 in Fallopian tubes, 475 
 Ciliary nerves, 414 
 Circulation, 229 
 
 in the heart, 222-235 
 
 in the arteries, 246 
 
 in the veins, 252 
 
 in the capillaries, 255 
 
 rapidity of, 261 
 
 peculiarities of, in difi'erent parts, 
 
 263 
 in liver, 279 
 in placenta, 527-581 
 Circulatory apparatus, development of, 
 
 566-587 
 Civilization, aptitude for, of diflferent 
 
 races, 364 
 Classification of cranial nerves, 387 
 Clot, formation of, 191 
 
 separation from serum, 192 
 bulfed and cupped, 195 
 Coagulation, 66 
 "of fibrin, 188 
 of blood, 190 
 
 of white substance of Schwann, in 
 nerve-fibres, 309 
 Colin, on unilateral mastication, 94 
 Cold, resistance to, by animals, 218 
 
 efi'ect of when long continued, 219 
 Colostrum, 275 
 Coloring matters, 70 
 of blood, 70, 183 
 of the skin, 171 
 of bile, 71, 142 
 of urine, 71 
 Commissure, of spinal cord, gray, 320 
 white, 321 
 
 transverse, of cerebrum, 327 
 of cerebellum, 327 
 Commissures, nervous, 313 
 
 olfactory, 322, 385 
 Congestion, of ear, &c., after division of 
 sympathetic, 422 
 
596 
 
 IX TEX. 
 
 Convolvulus, sexual apparatxis of, 442 
 Contact, of chorion and amnion, 533 
 
 of decidua vera and reflexa, 534 
 Consentaneons action of muscles, 348 
 Contraction, of stomacti during digestion, 
 112 
 
 of spleen, 174 
 
 of blood-clot, 191 
 
 of diaphragm and intercostal mus- 
 cles, 201 
 
 of posterior crico arytenoid nmscles, 
 206 
 
 of ventricles, 239 
 
 of muscles after death, 328 
 
 of sphincter ani, 354 
 
 of rectum, 354 
 
 of urinary bladder, 355 
 
 of pupil, under influence of light, 
 374, 418 
 after division of sympathetic, 
 423 
 Cookins, effect of, on food, 82 
 Cord, spinal, 319-340 
 
 umbilical, 533 
 
 withering and separation of, 590 
 Corpus callosum, 327 
 Corpus luteum, 478 
 
 of menstruation, 478-482 
 
 of pregnancy, 482-487 ■ 
 
 three weeks after menstruation, 480 
 
 four weeks after menstruation, 481 
 
 nine weeks after menstruation, 481 
 
 at end of second month of preg- 
 nancy, 484 
 
 at end of fourth month, 484 
 
 at term, 485 
 
 disappearance of, after delivery, 486 
 Corpora Malpighiana, of spleen, 174 
 Corpora striata, 323, 359 
 Corpora olivaria, 324 
 Corpora Wolffiana, 556-563 
 CosTE, on rupture of Graafian follicle in 
 
 menstruation, 474, 475 
 Cranial nerves, 385 
 
 classification of, 387 
 
 motor, 388 
 
 sensitive, 393 
 Creatine, 287-288 
 Creatinine, 288 
 Cremaster musc4e, formation of, 560 
 
 function of, in lower animals, 561 
 Crystals, of stearine, 55 
 
 and margarine, 56 
 
 of cholesterin, 143 
 
 of glyko-cholate of soda, 144, 145 
 
 of biliary matters of dog's bile, 148, 
 155 
 
 of urea, 285 
 
 of creatine, 287 
 
 of creatinine, 288 
 
 of urate of soda, 289 
 
 of uric acid, 296 
 
 of oxalic acid, 302 
 
 Crystals, of triple phosphate, 304 
 Crystallizable substances of organic ori- 
 gin, 47 
 Crossing of fibres in medulla oblongata, 
 324 
 of sensitive fibres in spinal cord. 
 
 845 
 of streams of blood in fcetal heart. 
 582, 583 
 Cecikshaxk, rupture of Graafiian folUcle 
 
 in menstruation, 474 
 Cumulus proligerus, 469 
 Cutaneous respiration, 217 
 
 perspiration, 271 
 Cuticle, exfoliation of, during fojtal life, 
 545 
 after birth, 590 
 Cysticercus, 439 
 
 transformation of into taenia, 440 
 production of, from eggs of taenia, 
 441 
 
 Death, a necessary consequence of life, 
 
 428 
 Decidua, 516 
 vera, 518 
 reflesa, 519 
 
 union with chorion, 521 
 its discharge in cases of abortion, 
 520 " 
 at the time of delivery, 535 
 Decussation of anterior columns of spinal 
 cord, 324 
 of optic nerves, 375, 376 
 Degeneration, fatty, of muscular fibres 
 
 of uterus, after delivery, 537 
 Deglutition, 100 
 
 retarded by division of Steno's duct. 
 99 
 by division of pneumogastric, 
 401 
 Dentition, first, 590 
 
 second, 591 
 Descent of the testicles, 559 
 
 of the ovaries, 562 
 Destructive assimilation, 282 
 Development of the impregnated egg, 
 
 of allantois, 503 
 
 of chorion, 510 
 
 of villosities of chorion, 511, 512 
 
 of decidua, 516 
 
 of placenta, 525-531 
 
 ot nervous system, 539 
 
 of eye, 542 
 
 of ear, 543 
 
 of skeleton, 543 
 
 of limbs, 544 
 
 of integument, 545 
 
 of alimentary canal, 546-548 
 
 of urinary passages, 548 
 
 of liver, 550 
 
 of pharynx and oesophagus, 551 
 
IKDEX. 
 
 597 
 
 Development of face, 553 
 
 of Wolffian bodies, 556 
 
 of kidneys, 557 
 
 of internal generative organs, 558 
 
 of circulatory apparatus, 56b" 
 
 of arterial system, 570 
 
 of venous system, 573 
 
 of hepatic circulation, 576 
 
 of heart, 578 
 
 of the body after birth, 588 
 Diabetes, 299 
 
 in foetus, 551 
 Diaphragm, action of in breathing, 201, 
 202 
 
 formation of, 552 
 Diaphragmatic hernia, 553 
 Diet, influence of on nutrition, 74-76 
 
 on products of respiration, 207, 225 
 
 on formation of urea, 286 
 of urate of soda, 289 
 Diffusion of gases in lungs, 203 
 Digestion, 83 
 
 of starch, 118 
 
 of fats, 121, 123 
 
 of sugar, 119 
 
 of organic substances, 110 
 
 time required for, 114 
 Digestive apparatus of fowl, 85 
 
 of ox, 86 
 
 of man, 87 
 Discharge of eggs from ovary, 450-453 
 
 independent of sexual intercourse, 
 467 
 
 mechanism of, 470 
 
 during menstruation, 474 
 Discus proligerus, 469 
 Distinction between corpora lutea of 
 menstruation and pregnancy, 486-487 
 Diurnal variations, in exhalation of car- 
 bonic acid, 216 
 
 in production of urea, 287 
 
 in density and acidity of urine, 293 
 Division of nerves, 311 
 
 of heart, into right and left cavities, 
 579 
 DoBSON, on variation in size of spleen, 
 
 173 
 Deafer, John C, on production of urea, 
 
 286-287 
 Drugs, effect of, on newly born infant, 
 
 589 
 Ductus arteriosus, 580 
 
 closure of. 580-581 
 
 venosus, 577 
 
 obliteration of, 578 
 Duodenal glands, 120 
 
 fistuU, 156 
 DuTKOCHET, on temperature of plants, 221 
 
 Ear, muscular apparatus of, 420 
 
 development of, 530 
 Earthy phosphates, 42, 45 
 
 in urine, 295 
 
 Earthy phosphates, precipitated by addi- 
 tion of an alkali, 296 
 Ectopia cordis, 553 
 Egg, 442-446 
 
 its contents, 447 
 
 where formed, 448 
 
 of frog, 450 
 
 of fowl, 453-454 
 
 changes in, while passing through 
 
 the oviduct, 450-453 
 pre-existence of, in ovary, 465 
 development of, at period of puberty, 
 
 466 
 periodical ripening and discharge, 
 
 467 
 discharge of, from Graafian follicle, 
 
 470 
 impregnation of, how accomplished, 
 
 463-464 
 development of, after impregnation, 
 
 488 
 of fowl, showing area vasculosa, 505 
 ditto, showing formation of allantois, 
 
 506 
 of fish, showing vitelline circulation, 
 
 567 
 attachment of, to uterine mucous 
 
 membrane, 521 
 discharge of from uterus, at the time 
 
 of delivery, 535 
 condition of in newly born infant, 
 564 
 Elasticity, of spleen, 173 
 
 of red globules of blood, 181 
 of lungs, 200 
 of costal cartilages, 202 
 of vocal chords, 206 
 of arteries, 246 
 Electrical current, effect of, on muscles, 
 329 
 on nerve, 331 
 
 different effects of direct and in- 
 verse, 338 
 Electrical fishes, phenomena of, 337 
 Electricity, no manifestations of in irri- 
 tated nerve, 338 
 Elevation of temperature, after division 
 
 of sympathetic, 421, 422 
 Elongation of heart in contraction, 240 
 
 anatomical causes of, 241 
 Embryo, formation of, 488 
 Embryonic spot, 492 
 Encephalon, 321 
 
 ganglia of, 326 
 Endosmosis, of fatty substances, 137 
 
 in capillary circulation, 260 
 Enlargement of amnion, during preg- 
 nancy, 532, 533 
 Eutozoa, encysted, 436 
 
 mode of production, 438 
 Epithelium, in saliva, 92 
 of gastric follicles, 102 
 of intestine, during digestion, 138 
 
598 
 
 INDEX. 
 
 Epidermis, exfoliation of, in foetal life, 545 
 
 after birth, 590 
 Epididymis, 560 
 Excretion, 282 
 
 nature of, 283 
 
 importance to life, 283-284 
 
 products of, 284 
 
 by placenta, 530 
 Excrementitious substances, 282 
 
 mode of formation of, 283 
 
 effect of retention of, 283 
 Exfoliation of cuticle, during fretal life, 
 545 
 
 after birth, 590 
 Exhalation of watery vapor, 39 
 
 from the lungs, 207 
 
 from the skin, 271 
 
 from the egg, during incubation, 507 
 
 of carbonic acid, 214-217 
 
 of nitrogen, 206 
 
 of animal vapor, 206 
 Exhaustion, of muscles, by repeated irri- 
 tation, 330 
 
 of nerves, by ditto, 332 
 Expiration, movements of, 202 
 
 after section of pneumogastric, 407 
 Extractive matters of the blood, 190 
 Eye, protection of, by movements of 
 pupil, 374, 418 
 
 by two sets of muscles, 419 
 Eyeball, inflammation of, after division 
 
 of 5th pair, 397 
 Eyelids, formation of, 543 
 
 Face, sensitive nerves of, 395 
 
 motor nerve, 390 
 
 development of, 553 
 Facial nerve, 390 
 
 sensibility of, 391 
 
 influence of, on muscular apparatus 
 of eye, 419 
 
 of nose, 420 
 
 of ear, 420 
 
 paralysis of, 391 
 Fallopian tubes, 455 
 
 formation of, 559, 562 
 Farinaceous substances, 47. 
 
 in food, 48 
 
 digestion of, 118 
 Fat, decomposition of, in the blood, 137 
 Fats, 54 
 
 proportion of, in dififerent kinds of 
 food, 56 
 
 condition, in the various tissues and 
 fluids, 57 
 
 internal source of, 61 
 
 decomposed in the body, 62 
 
 indispensable as ingredients of the 
 food, 74 
 Fatty matters of the blood, 189 
 Fatty degeneration of decidua, 536 
 
 of muscular fibres of uterus, after 
 delivery, 537 
 
 Female generative organs, 446 
 
 of frog, 449 
 
 of fowl, 453 
 
 of sow, 455 
 
 of human species, 456 
 development of, 562 
 Fermentation, 67 
 
 of sugar, 53 
 
 acid, of urine, 300 
 
 alkaline, of ditto, 302 
 Fibrin, 68 
 
 of the blood, 188 
 
 coagulation of, 188 
 
 varying quantity of, in blood of dif- 
 ferent veins, 189 
 Fifth pair of cranial nerves, 394 
 
 its distribution, 395 
 
 division of, paralyzes sensibility of 
 face, 395 
 and of nasal passages, 396 
 produces inflammation of eye- 
 ball, 397 
 
 lingual branch of, 398 
 
 small root of, 389 
 Fish, circulation of, 230 
 
 mode of progression, 370 
 
 formation of umbilical vesicle in, 
 498 
 
 vitelline circulation, in embryo of, 
 567 
 Fish, electrical, phenomena of, 337 
 Fissure, longitudinal, of brain and spinal 
 cord, 319 
 
 formation of, 541 
 Fissure of palate, 555 
 Fistula, gastric, Dr. Beaumont's case of, 
 103 
 
 mode of operating for, 104 
 
 duodenal, 156 
 Foetal circulation, first form of, 566 
 
 . second form of, 568 
 Follicles, of stomach, 101 
 
 of Lieberkiihn, 119 
 
 of Brunner's glands, 120 
 
 Graafian, 448, 470 
 
 of uterus, 517 
 Food, 73 
 
 composition of, 80, 81 
 
 daily quantity required, 81 
 
 effect of cooking, on, 82 
 Foramen ovale, 581 
 
 valve of, 585 
 
 closure of, 585 
 Force, nervous, nature of, 335 
 Formation of sugar in liver, 165 
 
 in foetus, 551 
 Fossa ovalis, 586 
 Functions, animal, 27 
 
 vegetative, 27 
 
 of teeth, 89 
 
 of saliva, 98 
 
 of gastric j,uice, 109 
 
 of intestinal juices, 118 
 
INDEX. 
 
 599 
 
 Functions, of pancreatic juice, 123 
 of bile. 158 
 of spleen, 175 
 of nuicus, 2G9 
 of sebaceous matter, 270 
 of perspiration, 272 
 of the tears, 274 
 
 Galvanism, action of, on muscles, 329 
 
 on nerves, 331 
 Ganglion, of spinal cord, 348 
 
 of tuber annulai-e, 377 
 
 of mediilla oblongata, 378 
 
 Casserian, 393 
 
 of Andersch, 393, 398 
 
 pneumogastric, 393, 400 
 
 ophthalmic, 414 
 
 spheno-palatine, 414 
 
 submaxillary, 414 
 
 otic, 415 
 
 semilunar, 416 
 
 impar, 416 
 Ganglionic system of nerves, 319,414 
 Ganglia, nervous, 312 
 
 of radiata, 313 
 
 of moUusca, 315 
 
 of articulata, 316 
 
 of posterior roots of spinal nerves, 
 320 
 
 of alligator's brain, 322 
 
 of rabbit's brain, 323 
 
 of medulla oblongata, 324, 378 
 
 of human brain, 326 
 
 of great sympathetic, 414 
 Gases, diffusion of, in lungs, 203 
 
 absorption and exhalation of, by 
 lungs, 208 
 by the tissues, 212 
 Gastric follicles, 101 
 Gastric juice, mode of obtaining, 105 
 
 composition of, 107 
 
 action on food, 109 
 
 interference with Trommer's test. Ill 
 
 interference with action of starch 
 and iodine, 112 
 
 daily quantity of, 115 
 
 solvent action of, on stomach, after 
 death, 117 
 Gelatine, how produced, 32 
 
 effect of feeding animals on, 77 
 Generation, 429 
 
 spontaneous, 429 
 
 of infusoria, 432 
 
 of parasites, 434 
 
 of encysted entozoa, 436 
 
 of tsenia, 438 
 
 sexual, by germs, 442 
 Germ, nature of, 442 
 Germination, heat produced in, 221 
 Germinative vesicle, 447 
 
 disappearance of, in mature egg, 488 
 Germinative spot, 447 
 Gills, of fish, 197 
 
 Gills, of menobranchus, 198 
 Glands, of Brunner, 120 
 mesenteric, 134 
 vascular, 175 
 Meibomian, 270 
 perspiratory, 271 
 action of, in secretion, 265 
 Glandulse, solitariae and agminatse, 128 
 Globules, of blood, 178 
 red, 179 
 
 different appearances of, under 
 
 microscope, 179, 180 
 mutual adhesion of, 180 
 color, consistency, and structure 
 
 of, 181 
 action of water on, 182 
 composition of, 183 
 size, &c., in different animals, 
 184,185 
 white, 185 
 
 action of acetic acid on, 186 
 red and white, movement of, in 
 circulation, 257 
 Globuline, 68, 183. 
 Glomeruli, of Wolffian bodies, 557 
 Glosso -pharyngeal nerve, 398 
 
 action of, in swallowing, 399 
 Glottis, movements of, in respiration, 204 
 in formation of voice, 402 
 closure of, after section of pneumo- 
 gastrics, 405 
 Glycine, 146 
 Glyco-cholic acid, 146 
 Glyco-cholate of soda, 146 
 its crystallization, 144 
 Glycogenic function of liver. 165 
 
 in foetus, 551 
 Glycogenic matter, 169 
 
 its conversion into sugar, 170 
 Graafian follicles, 448 
 structure of, 469 
 
 rupture of, and discharge of egg, 470 
 ruptured during menstruation, 474 
 condition in foetus at term, 564 
 Gray substance, of nervous system, 312 
 of spinal cord, 320 
 of brain, 326 
 
 its want of irritability, 360 
 Great sympathetic, 319-414 
 anatomy of, 415 
 
 sensibility and excitability of, 417 
 connection of, with special senses, 
 
 418, 421 
 division of, influence on animal heat, 
 
 422 
 on pupil and eyelids, 423 
 reflex actions of, 424 
 Gubernaculum testis, 560 
 
 function of, in lower animals, 561 
 Gustatory nerve, 398 
 
 Hammoxd, Dr. Wm. A., on effects of 
 non-nitrogenous diet, 76 
 
600 
 
 INDEX. 
 
 Hammoxd, on production of urea, 2^6 
 
 Hsematine, 70, 183 
 
 Hairs, formation of, in embryo, 545 
 
 Hare-lip, 554 
 
 Harvey, on motions of heart. 238, 240, 
 
 245 
 Heart, 230 
 
 of fish, 230 
 of reptiles, 231 
 of mammalians, 232 
 of man, 233 
 
 circulation of blood through, 235 
 sounds of, 235 
 movements of, 238 
 impulse, 244 
 development of, 578 
 Heat, vital, of animals, 218 
 of plants, 221 
 how produced, 222 
 increased by division of sympathetic 
 nerve, 422 
 Hemispheres, cerebral, 322, 359 
 
 remarkable cases of injury to, 360 
 eifect of removal, on pigeons, 361- 
 
 362 
 effect of disease, in man, 363 
 comparative size of, in different races , 
 
 364 
 functions of, 365 
 development of, 540 
 Hemorrhage, from placenta, in parturi- 
 tion, 535 
 Hepatic circulation, 279 
 development of, 576 
 Herbivorous animals, respiration of, 18, 
 207 
 urine of, 287, 289 
 Hernia, congenital, diaphragmatic, 553 
 
 umbilical, 548 
 Hernia, inguinal, 562 
 Hippurate of soda, 289 
 Hunger and thirst, continue after divi- 
 sion of pneumogastric, 411 
 Hydrogen, displacement of gases in blood 
 by, 209 
 exhalation of carbonic acid in an 
 atmosphere of, 213 
 Hygroscopic property of organic sub- 
 stances, 65 
 Hypoglossal nerve, 392. See Sublingual. 
 
 Impulse, of heart, 244 
 Infant, newly-born, characteristics of, 588 
 Inflammation, changes of capillary cir- 
 culation in, 259 
 of eyeball, after division of 5th pair, 
 397 
 Infusoria, 431 
 
 different kinds of 432 
 conditions of their production, 432 
 Schultze's experiment on generation 
 of, 434 
 Inguinal hernia, congenital, 562 
 
 Injection of placental sinuses from ves- 
 sels of uterus, 529 
 Inorganic substances, as proximate prin- 
 ciples, 37 
 
 their source and destination, 46 
 Inosculation, of veins, 253 
 
 of capillaries, 256-257 
 
 of nerves, 312 
 Insalivation, 92 
 
 importance of, 99 
 
 function of, 100 
 Inspiration, how accomplished, 201 
 
 movements of glottis in, 205 
 Instinct, nature of, 382, 383 
 Integument, respiration by, 217 
 
 development of, 545 
 Intellectual powers, 364-383 
 
 in animals, 384 
 Intestine, of fowl, 85 
 
 of man, 87 
 
 juices of, 118 
 
 digestion in, 118, 127 
 
 epithelium of, 138 
 
 disappearance of bile in, 158 
 
 development of, 494, 495, 499, 547 
 Intestinal digestion, 125 
 Intestinal juices, 118 
 
 action of, on starch, 119 
 Involution of uterus after delivery, 537 
 Iris, movements of, 374, 418 
 
 after division of sympathetic, 423 
 Irritability, of gastric mucous membrane, 
 105 
 
 of the heart, 241 
 
 of muscles, 328 
 
 of nerves, 330 
 
 Jackson, Prof. Samuel, on digestion of fat 
 
 in intestine, 122 
 Jaundice, 142 
 
 yellow color of urine in, 299 
 
 Kidneys, peculiarity of circulation in, 
 263 
 elimination of medicinal substances 
 
 by, 298 
 formation of, 557 
 KiJCHENMEiSTER, experiments on produc- 
 tion of tcenia from cysticercus, 
 440 
 of cysticercus from eggs of 
 tjenia, 441 
 
 Lachrymal secretion, 273 
 
 its function, 274 
 Lactation, 274 
 
 variations in composition of milk 
 during, 275-278 
 Lacteals, 134-135 
 
 and lymphatics, 136 
 Larynx, action of, in respiration, 205 
 in formation of voice, 402 
 
 nerves of, 400 
 
INDEX. 
 
 601 
 
 Larynx, protective action of, 404 
 
 movements in respiration, 205,404 
 Layers, external and internal, of blasto- 
 dermic membrane, 490 
 Lead, salts of, action in distinguishing 
 
 the biliary matters, 145-14(3 
 Lehmann, on formation of carbonates in 
 blood, 45 
 on total quantity of blood, 196 
 on effects of non-nitrogenous diet, 
 76 
 Ledckakt, on production of cysticercus, 
 
 441 
 Ligament of the ovary, formation of, 563 
 Limbs, formation of, in frog, 496 
 in human eraWyo, 544 
 Liver, vascularity of, 279 
 lobules of, 280 
 secreting cells, 281 
 formation of sugar in, 165 
 congestion of, after feeding, 172 
 development of, 560, 576 
 Liver cells, 280 
 
 their action in secretion, 281 
 Liver-sugar, formation of, 165 
 after death, 168 
 in foetus, 551 
 Lobules, of lung, 200 
 
 of liver, 279 
 Local production of carbonic acid, 212 
 
 of animal heat, 226 
 Local variations of cii'culation, 263 
 LoNGET, on interference of albuminose 
 with Trommer's test. Ill 
 on sensibility of glosso-pharyngeal 
 
 nerve, 398 
 on irritability of anterior spinal 
 roots, 343 
 LoNGET AND Matteucci, experiment on 
 signs of electricity in an irritated 
 nerve, 338 
 Lungs, structure of, in reptiles, 199 
 in man, 200 
 alteration of, after division of pneu- 
 mogastrics, 407 
 Lymph, 135 
 Lymphatics, 133 
 
 Magnus, on proportions of oxygen and 
 
 carbonic acid in blood, 209 
 Male organs of generation, 458 
 
 development of, 558 
 Malpighian bodies of spleen, 174 
 Mammalians, circulation in, 231 
 Mammary gland, structure of, 274 
 
 secretion of, 275 
 Mastication, 89 
 
 unilateral, in ruminating animals, 
 94 
 
 retarded by suppressing saliva, 99 
 Meconium, 549 
 Medulla oblongata, 324, 378 
 
 ganglia of, 325-326 
 
 Medulla oblongata, reflex action of, 379- 
 382 
 effect of destroying, 381 
 
 development of, 540 
 Meibomian glands, 270 
 Melanine, 71 
 
 Membrane, blastodermic, 490 
 Membrana granulosa, 469 
 Membrana tympani, action of, 421 
 Memory, connection of, with cerebral 
 
 hemispheres, 362 
 Menobranchus, size of blood-globules in, 
 185 
 
 gills of, 198 
 
 spermatozoa of, 459 
 Menstruation, 472 
 
 commencement and duration of, 473 
 
 phenomena of, 473 
 
 rupture of Graafian follicles in, 474 
 
 suspended during pregnancy, 473, 
 486 
 Mesenteric glands, 134 
 Michel, Dr. Myddleton, rupture of Graaf- 
 ian follicle in menstruation, 474 
 Milk, 274 
 
 composition and properties of, 275 
 
 microscopic characters, 276 
 
 souring and coagulation of, 277 
 
 variations in, during lactation, 278 
 Milk-sugar, 51, 52 
 
 converted into lactic acid, 277 
 Mollusca, nervous system of, 315 
 Moore and Pennock, experiments on 
 
 movements of heart, 240 
 Motor cranial nerves, 388 
 Motor nervous fibres, 315 
 Motor oculi communis, 389 
 
 externus, 389 
 Movements, of stomach, 112 
 
 of intestine, 130 
 
 of heart, 238 
 
 of chest in respiration, 201 
 
 of glottis, 204 
 
 associated, 348 
 
 of foetus, 533 
 Mucosine, 69 
 Mucous follicles, 268 
 Mucous membrane, of stomach, 101 
 
 of intestine, 119, 128, 129 
 
 of uterus, 516 
 Mucus, 268 
 
 composition and properties of, 269 
 
 of mouth, 93 
 
 of cervix uteri, 456 
 Muscles, irritability of, 328 
 
 directly paralyzed by sulpho-cya- 
 nide of potassium, 330 
 
 consentaneous action of, 348 
 
 of respiration, 201-202 
 Muscular fibres, of spleen, 173 
 
 of heart, spiral and circular, 242 
 Muscular irritability, 328 
 
 duration after death, 329 
 
602 
 
 INDEX. 
 
 Muscular irritability, esliausted by re- 
 peated irritation, 330 
 Masculine, 70 
 
 Nails, formation of, in embryo, 545 
 NtGEiEE, on rupture of Graafian follicle, 
 
 in menstruation, 474 
 Nerve-cells, 312 
 Nerves, division of, 311 
 inosculation of, 312 
 irritability of. 32S 
 spinal, 319, 320, 342 
 cranial, 385 
 olfactory, 385 
 optic, 386 
 auditory, 386 
 oculo-motorius, 389 
 patheticus, 389 
 motor externus, 3S9 
 masticator, 389 
 facial, 390 
 sublingual, 392 
 spinal accessory, 392 
 trifacial (oth pair), 394 
 glosso-pbaryngeal, 398 
 pneumogastric, 399 
 superior and inferior laryngeal, 400 
 great sympathetic, 414 
 Nervous filaments, 308 
 of brain, 309 
 of sciatic nerve, 310 
 motor and sensitive, 343 
 Nervous force, tow excited, 330 
 nature of, 335 
 
 mode of transmission, 336-339 
 Nervous tissue, two kinds of, 307 
 Nervous irritability, 328 
 how shown, 331 
 duration of, after death, 331 
 exhausted by excitement, 332 
 destroyed by woorara, 333 
 distinct from muscular, 335 
 nature of, 335-339 
 Nervous system, 305 
 
 general structure and functions of, 
 
 305-327 
 of radiata, 313 
 of moUusca, 315 
 of articulata, 316 
 of vertebrata, 318 
 reflex action of, 314 
 Network, capillary, in Peyer's glands, 
 128 
 in web of frog's foot, 256 
 in lobule of liver, 280 
 Newly-born infant, weight of, 558 
 respiration in, 558 
 nervous phenomena of, 589 
 comparative size of organs in, 590 
 Newport, on temperature of insects, 221 
 Nitric acid, action of, on bile-pigment, 
 150 
 precipitation of uric acid by, 295 
 
 Nitrogen, exhalation of. in respiration, 
 
 206"' 
 Nutrition, 26-29 
 
 Obliteration, of ductus venosus, 578 
 
 of ductus arteriosus, 580 
 Oculo-motorius nerve, 389 
 CEsophagus, paralysis of, after division 
 of pneumogastric, 401 
 development of, 552 
 CEstruation, phenomena of, 471 
 Oleaginous substances, 54 
 
 in difi'erent kinds of food, 56 
 condition of, in the tissues and fluids, 
 
 57 
 partly pirodTTced in the body, 61 
 decomposed in the body, 62 
 
 in the blood, 137 
 indispensable as ingredients of the 
 
 food, 74 
 insuiEcient for nutrition, 76 
 Olfactory apparatus, protected by two 
 sets of muscles, 420 
 
 commissures, 322, 323, 385 
 Olfactory ganglia, 322 
 
 their function, 358 
 Olfactory nerves, 385 
 Olivary bodies, 324 
 Omphalo-mesenterio vessels, 567-569 
 Ophthalmic ganglion, 414 
 Optic ganglia, 322, 373 
 Optic nerves, 386 
 
 decussation of, 375-376 
 Optic thalami, 323, 359 
 
 development of, 540 
 Organs of special sense, development of, 
 
 542 
 Organic substances, 63 
 
 indefinite chemical composition of, 
 
 64 
 hygroscopic properties, 65 
 coagulation of, 66 
 catalytic action, 66 
 putrefaction, 67 
 source and destination, 72 
 digestion of, 110 
 Origin, of plants and animals, 429 
 of infusoria, 431 
 of animal and vegetable parasites, 
 
 434 
 of encysted entozoa, 436 
 Ossification of skeleton, 544 
 Osteine, 70 
 Otic ganglion, 415 
 Ovary, 443 
 
 of tfenia, 443 
 of frog, 449 
 of fowl, 453 
 
 of human female, 455, 456 
 Ovaries, descent of, in foetus, 562 
 
 condition at birth, 564 
 Oviparous and viviparous animals, dis- 
 tinction between, 465 
 
INDEX. 
 
 603 
 
 Oxalic acid, produced in urine, 302 
 Oxygen, absorbed in respiration, 207 
 state of solution in blood, 209 
 dissolved by blood-globules, 210 
 absorbed by tbe tissue-, 212 
 exhaled by plants, 225 
 
 Palate, formation of, 555 
 Pancreatic juice, 121 
 
 mode of obtaining, 122 
 composition of, 123 
 action on fat, 123 
 daily quantity of, 123 
 Pancreatine, 68 
 
 in pancreatic juice, 123 
 Panizza, experiment on absorption by 
 
 bloodvessels, 131 
 Paralysis, after division of anterior root 
 of spinal nerve, 341 
 direct, after lateral injury of spinal 
 
 cord, 344 
 crossed, after lateral injury of brain, 
 
 345 
 facial, 341, 391 
 
 of muscles, by sulplio-cyanide of po- 
 tassium, 330, 352 
 of motor nerves, by woorara, 353 
 of sensitive nerves, by strychnine, 
 
 353 
 of voluntary motion and sensation, 
 after destroying tuber annulare, 
 377 
 of pharynx and oesophagus, after 
 
 section of pneumogastrics, 401 
 of larynx, 402-412 
 of muscular coat of stomach, 411 
 Paraplegia, reflex action of spinal cord, 
 
 in, 351 
 Parasites, 434 
 
 conditions of development of, 435 
 mode of introduction into body, 
 
 436 
 sexless, reproduction of, 436-441 
 Parotid saliva, 93 
 Parturition, 534-535 
 Par vagum, 399. See Pneumogastric 
 Patheticus nerve, 389 
 Pelvis, development of, 554 
 Pennock and Moore, experiments on 
 
 movements of heart, 240 
 Pepsine, 69 
 
 in gastric jxiice, 108 
 Perception of sensations, afterremoval of 
 hemispheres, 362 
 destroyed, after removal of tuber 
 annulare, 377 
 Periodical ovulation, 465 
 Peristaltic motion, of stomach, 112-113 
 of intestine, 130 
 of oviduct, 450-452 
 of Fallopian tubes, 475 
 Perspiration, 271 
 
 daily quantity of, 272 
 
 Perspiration, composition and properties 
 of, 272 
 function, in regulating temperature, 
 273 
 Pettenkofer's test for bile, 151 
 Peyer's glands, 128 
 Pharynx, action of, in swallowing, 40l 
 
 formation of, 551 
 Phosphate of lime, its proportion in the 
 animal tissues and fluids, 42 
 in the urine, 295 
 precipitated by alkalies, 296 
 Phosphate, triple, in putrefying urine, 
 
 304 
 Phosphates, alkaline, 45 
 in urine, 295 
 earthy, 42-45 
 
 in urine, 295 
 of magnesia, soda, and potass, 
 45 
 Phosphorus, not a proximate principle, 
 
 31 
 Physiology, definition of, 17 
 Phrenology, 367 
 
 objections to, 368 
 practical difficulties of, 368-369 
 Pigeon, after removal of cerebrum, 362 
 
 of cerebellum, 372 
 Placenta, 523 
 
 comparative anatomy of, 524 
 formation of, in human species, 525 
 . foetal tufts of, 527 
 maternal sinuses of, 527 
 injection of, from uterine vessels, 529 
 function of, 530 
 separation of, in delivery, 535 
 Placental circulation, 568, 570 
 Plants, vital heat of, 221 
 
 generative apparatus of, 442 
 Plasma of the blood, 187 
 Pneumic acid, 21] 
 Pneumogastric nerve, 399 
 its distribution, 400 
 action of, on pharynx and oesopha- 
 gus, 401 
 on larynx, 402 
 in formation of voice, 403 
 in respiration, 404 
 effect of its division, on respiratory 
 
 movements, 406-407 
 cause of death after division of, 
 
 409-410 
 influence of, on oesophagus and sto- 
 mach, 411-412 
 Pneumogastric ganglion, 400 
 PoGGiALE, on glycogenic matter in but- 
 cher's meat, 170 
 Pons Varolii, 324, 327 
 Portal blood, quantity of fibrin in, 189 
 
 temperature of, 227 
 Portal vein, in liver, 279 
 development of, 576 
 Posterior columns of spinal cord, 321 
 
604 
 
 INDEX. 
 
 Primitive trace, 492 
 Production, of sugar in liver, 165 
 
 of carbonic acid, 214 
 
 of animal heat, 218 
 
 of urea in blood, 285 
 
 of infusorial animalcules, 431 
 
 of animal and vegetable parasites, 
 434 
 Proximate principles, 29 
 
 definition of, 31 
 
 mode of extraction, 32 
 
 manner of their association, 33 
 
 varying proportions of, 34 
 
 three distinct classes of, 35 
 Proximate principles of the first class 
 (inorganic), 37 
 
 of the second class (crystallizable 
 substances of organic origin), 47 
 
 of the third class (organic sub- 
 stances), QS 
 Ptyaline, 93 
 Puberty, period of, 467 
 
 signs of, in female, 472 
 Pulsation, of heart, 235 
 
 in living animal, 239 
 
 of arteries, 247, 248 
 Pupil, action of, 374, 418 
 
 contraction of, after division of sym- 
 pathetic, 423 
 Pupillary memi)rane, 542 
 Putrefaction, 67 
 
 of the urine, 300 
 Pyramids, anterior, of medulla oblon- 
 gata, 324 
 
 Quantity, daily, of water exhaled, 39 
 
 of food, 81 
 
 of saliva, 96 
 
 of gastric juice, 114 
 
 of pancreatic juice, 123 
 
 of bile, 153 
 
 of carbonic acid exhaled, 214 
 
 of perspiration, 272 
 
 of urine, 291 
 
 of urea, 286 
 
 of urate of soda, 289 
 Quantity, entire, of blood in body, 196 
 
 Rabbit, brain of, 323 
 
 Races of men, different capacity of, for 
 
 civilization, 364 
 Radiata, nervous system of, 313 
 Rapidity of circulation, 261 
 
 of transmission of nervous force, 
 336-337 
 Reactions, of starch, 50 
 
 of sugar, 52 
 
 of fat, 54 
 
 of saliva, 93 
 
 of gastric juice, 107-108 
 
 of intestinal juice, 121 
 
 of pancreatic juice, 123 
 
 of bile, 150 
 
 Reactions, of mucus, 269 
 
 of milk, 276 
 
 of urine, 295 
 Reasoning powers, 363-364 
 
 in animals, 383 
 Red globules of blood, 179 
 Reflex action, 314 
 
 in centipede, 317 
 
 of spinal cord, 348, 382 
 
 of medulla oblongata, 379, 382 
 
 of tuber annulare, 378, 382 
 
 of brain, 383 
 
 of optic tubercles, 384 
 
 in newly born infant, 589 
 Regeneration, of uterine mucaus mem- 
 brane after pregnancy, 536 
 
 of walls of uterus, 537-538 
 Regnault and Reiset, on absorption of 
 
 oxygen, 225 
 Reid, Dr. John, experiment on crossing 
 
 of streams in foetal heart, 583 
 Reproduction, 427 
 
 nature and object of, 427-429 
 
 of parasites, 434 
 
 of tasnia, 438 
 
 by germs, 442 
 Reptiles, circulation of, 231 
 Respiration, 197 
 
 by gills, 198 
 
 by lungs, 199 
 
 by skin, 217 
 
 changes in air during, 206 
 
 changes in blood, 207 
 
 of newly born infant, 588 
 Respiratory movements of chest, 201 
 
 of glottis, 204 
 
 after section of pneumogastrics,404- 
 406 
 
 after injury of spinal cord, 380 
 Restiform bodies, 325 
 Rhythm of heart's movements, 244 
 Rotation of heart during contraction, 
 
 243 
 Round ligament of the uterus, formation 
 of, 563 
 
 of liver, 578 
 Rumination, movements of, 94 
 Rupture of Graafian follicle, 470 
 
 in menstruation, 474 
 Rutting condition, in lower animals, 471 
 
 Saccharine substances, 51, 52, 54 
 
 in stomach and intestine, 118 
 
 in liver, 165 
 
 in blood, 171 
 
 in urine, 299 
 Saliva, 92 
 
 different kinds of, 93 
 
 daily quantity of, 96 
 
 action on boiled starch, 96 
 
 variable, 97 
 
 does not take place in stomach, 98 
 
 physical function of saliva, 98 
 
INDEX. 
 
 605 
 
 Saliva, quantity absorbed by difTerent 
 
 kinds of food, 100 
 Salivary glands, 93 
 Salts, biliary, 143 
 of the blood, 190 
 of urine, 288 
 Saponification, of fats, 55 
 ScuAKLiNG, on diurnal variations in exha- 
 lation of carbonic acid, 216 
 ScHULTZE, experiment on generation of 
 
 infusoria, 434 
 Scolopendra, nervous system of, 316 
 Sebaceous matter, 269 
 
 composition and properties of, 270 
 function of, 271 
 in foetus, 545 
 Secretion, 265 
 
 varying activity of, 267 
 of saliva, 93 
 of gastric juice, 105 
 of intestinal juice, 120 
 of pancreatic juice, 122 
 of bile, 153, 278 
 of sugar in liver, 165 
 of mucus, 268 
 of sebaceous matter, 269 
 of perspiration, 271 
 of the tears, 273 
 of bile in foetus, 551 
 Segmentation of the vitellus, 489 
 Seminal fluid, 458 
 
 mixed constitution of, 462 
 Sensation, remains after destruction of 
 hemispheres, 362 
 lost after removal of tuber annulare, 
 
 377 
 special, conveyed by pneumogastric 
 nerve, 379, 406 
 Sensation and motion, distinct seat of, in 
 nervous system, 340 
 in spinal cord, 343 
 Sensibility, of nerves to electric current, 
 337 
 and excitability, definition of, 341 
 seat of, in spinal cord, 343 
 in brain, 357 
 of facial nerve, 391 
 of sublingual nerve, 392 
 of spinal accessory, 393 
 of great sympathetic, 417 
 Sensibility, special, of olfactory nerves, 
 385 
 of optic nerves, 386 
 of auditory nerves, 386 
 of lingual branch of 5th pair, 398 
 of glosso-pharyngeal, 399 
 of pneumogastric, 408 
 Sensitive nervous filaments, 315 
 Sensitive fibres, crossing of, in spinal 
 cord, 345 
 of facial nerve, source of, 390 
 Sensitive cranial nerves, 393 
 
 Septa, inter-auricular and inter- ventricu- 
 lar, formation of, 581 
 S£quakd, on crossing of sensitive fibres 
 
 in spinal cord, 345 
 Serum, of the blood, 192 
 Sexes, distinctive characters of, 444 
 Sexless entozoa, 436 
 Sexual generation, 442 
 Shock, effect of, in destroying nervous 
 
 irritability, 330 
 SiEBOLD, on production of tienia from 
 
 cysticercus, 440 
 Sinus terminalis, of area vasculosa, 505 
 Sinuses, placental, 527 
 Skeleton, development of, 543 
 Skin, respiration by, 217 
 
 sebaceous glands of, 269 
 perspiratory glands of, 271 
 development of, 545 
 Smell, ganglia of, 358 
 nerves of, 385 
 
 injured by division of 5tli pair, 396 
 Smith, Dr. Southwood, on cutaneous and 
 
 pulmonary exhalation, 272 
 Solar plexus of sympathetic nerve, 416 
 Sounds, of heart, 235 
 how produced, 236 
 vocal, how produced, 420 
 destroyed by section of inferior la- 
 ryngeal nerves, 403 
 of spinal accessory, 404 
 Sounds, acute and grave, transmitted by 
 
 memljrana tympani, 421 
 Species, mode of continuation, 429 
 Spermatic fluid, 458 
 
 mixed constitution of, 462 
 Spermatozoa, 458-459 
 movements of, 460 
 formation of, 461 
 Spina bifida, 543 
 Spinal accessory, 392 
 sensibility of, 393 
 
 communication of, with pneumogas- 
 tric, 400 
 Influence of, on larynx, 404 
 Spinal column, formation of, 493, 543 
 Spinal cord, 319-340 
 
 commissures of, 320 
 anterior and posterior columns, 321 
 origin of nerves from, 319, 320 
 sensibility and excitability of, 343 
 crossed action of, 344 
 reflex action of, 348 
 protective action of, 353 
 influence on sphincters, 354 
 effect of injury to, 355 
 on respiration, 380 
 formation of, in embryo, 493, 543 
 Spinal nerves, origin of, 319, 321 
 Spleen, 173 
 
 Malpighian bodies of, 174 
 extirpation of, 176 
 Spontaneous generation, 429 
 
606 
 
 INDEX. 
 
 Starch, 47 
 
 proportion of, iu different kinds of 
 
 food, 48 
 varieties of, 48 
 reactions of, 50 
 action of saliva on, 96 
 digestion of, 118 
 Starfish, nervous system of, 313 
 St. Martin, case of gastric fistula in, 103 
 Strabismus, after division of motor oculi 
 communis, 389 
 of motor externus, 389 
 Striated bodies, 359 
 Sublingual gland, secretion of, 93-94 
 
 nerve, 392 
 Submaxillary ganglion, 414 
 
 gland, secretion of, 93-94 
 Sudoriparous glands, 271 
 Sugar, 51 
 
 varieties of, 51 
 
 composition of, 52 
 
 tests for, 52 
 
 fermentation of, 52 
 
 proportion in diflferent kinds of food, 
 
 54 
 source and destination, 54 
 discharged by urine in disease, 299 
 Sugar in liver, formation of, 165 
 percentage of, 167 
 produced in hepatic tissue, 168 
 from glycogenic matter, 169 
 absorbed by hepatic blood, 171 
 decomposed in circulation, 171 
 Sulphates, alkaline, in urine, 296 
 Sulphur of the bile, 147 
 
 not discharged with the feces, 161- 
 162 
 Swallowing, 100 
 
 retarded by suppression of saliva, 99 
 by division of pneumogastic, 411 
 Sympathetic nerve, 414 
 its distribution, 415 
 sensibility and excitability of, 417 
 influence of, on special senses, 418 
 onpupil, 418, 419, 423 
 on nutrition of eyeball, 397-398 
 on nasal passages, 420 
 on ear, 421 
 
 on temperature of particular 
 parts, 421-422 
 reflex actions of, 424 
 
 Tadpole, development of, 494-495 
 
 transformation into frog, 496 
 Taenia, 438 
 
 produced by metamorphosis of cys- 
 ticercus, 440 
 
 single articulation of, 443 
 Tapeworm, 438 
 
 mode of generation, 439 
 Taste, nerves of, 398-399 
 
 of alimentary substances, developed 
 by cooking, 82 
 
 Taurine, 147 
 Tauro-cholate of soda, 146 
 
 microscopic characters of, 144-145 
 Tauro-cholic acid, 147 
 Tears, 273 
 
 their function, 274 
 Teeth, of serpent, 89 
 of polar bear, 90 
 of horse, 90 
 of man, 91 
 
 first and second sets of, 590-591 
 Temperature, of the blood, 219 
 
 of diff'erent species of animals, 220 
 of the blood in diflferent organs, 227 
 elevation of, after section of sympa- 
 thetic nerve, 422 
 Tensor tympani, action of, 421 
 Tests, for starch, 50 
 for sugar, 52 
 for bile, 150 
 Pettenkofer's, 151 
 Testicles, 461 
 
 periodical activity of, in flsh, 433 
 development of, 558 
 descent of, 559 
 Tetanus, pathology of, 350 
 Thalami, optic, in rabbit, 323 
 in man, 326 
 function of, 359. 
 Thoracic duct, 134 
 Thoracic respiration, 380 
 Tongue, motor nerve of, 392 
 
 sensitive, 398-399 
 Trichina spiralis, 436 
 Tricuspid valve, 234. See Auriculo- 
 
 ventricular. 
 Triple phosphate, in putrefying urine, 
 
 304 
 Trommer's test for sugar, 52 
 
 interfered with by gastric juice, 111 
 Tuber annulare, 325 
 
 efi'ect of destroying, 377 
 action of, 378 
 Tubercula quadrigemina, 322, 323, 373 
 reflex action of, 374 
 crossed action of, 375 
 development of, 540 
 Tubules of uterine mucous membrane, 
 
 517 
 Tufts, placental, 527 
 
 Tunica vaginalis testis, formation of, 561 
 Tympanum, function of, in hearing, 421 
 
 Umbilical cord, formation of, 533 
 
 withering and separation of, 590 
 Umbilical hernia, 548 
 Umbilical vesicle, 498 
 
 in human embryo, 499 
 
 in chick, 506 
 
 disappearance of, 533 
 Umbilical vein, formation of, 570-577 
 
 obliteration of, 578 
 Umbilicus, abdominal, 494 
 
INDEX. 
 
 607 
 
 Umbilicus, amniotic, 502 
 
 decidual, 519 
 Unilateral mastication, in ruminating 
 
 animals, 94 
 Urate of soda, 288 
 
 its properties, source, daily quantity, 
 kc, 289 
 Urates of potass and ammonia, 289 
 Urachus, 549 
 Urea, 284 
 
 source of, 285 
 
 mode of obtaining, 285 
 
 conversion into carbonate of am- 
 monia, 285 
 
 daily quantity of, 286 
 
 diurnal variations in, 287 
 
 decomposed in putrefaction of urine, 
 302 
 Uric acid, 288, 296 
 Urine, 290 
 
 general character and properties of, 
 291 
 
 quantity and specific gravity, 292 
 
 diurnal variations of, 293 
 
 composition of, 294 
 
 reactions, 295-296 
 
 interference with Trommer's test, 
 297 
 
 accidental ingredients of, 297 
 
 acid fermentation of, 300-301 
 
 alkaline fermentation of, 302 
 
 final decomposition of, 304 
 Urinary bladder, paralysis and inflam- 
 mation of, after injury to spinal 
 cord, 355 
 
 formation of, in embryo, 548 
 Urosacine, 71 
 Uterus, of lower animals, 455 
 
 of human female, 456 
 
 mucous membrane of, 517 
 
 changes in, after impregnation, 518 
 
 involution of, after delivery, 537 
 
 development of, in foetus, 562 
 
 position of, at birth, 564 
 Uterine mucous membrane, 516 
 
 tubules of, 517 
 
 conversion into decidua, 519 
 
 exfoliation of, at the time of delivery, 
 535 
 
 its renovation, 536 
 
 Valve, Eustachian, 581-582 
 
 of foramen ovale, 585 
 Valves, cardiac, action of, 234 
 
 cause of heart's sounds, 236 
 Vasa deferentia, formation of. 559-560 
 Vapor, watery, exhalation of, 39 
 
 from lungs, 207 
 
 from the skin, 271 
 Variation, in quantity of bile in differ- 
 ent animals, 154-157 
 
 in production of liver-sugar, 171-172 
 
 in size of spleen, 173 
 
 Variation, in rapidity of coagulation of 
 blood, 192 
 in size of glottis in respiration, 205 
 in exhalation of carbonic acid, 214- 
 
 216 
 in temperature of blood in different 
 
 parts, 227 
 in composition of milk during lac- 
 tation, 278 
 in quantity of urea, 286-287 
 in density and acidity of urine, 291 
 -293 
 Varieties of starch, 48 
 of sugar, 51 
 of fat, 54 
 
 of biliary salts in diiferent animals, 
 158 
 Vegetable food, necessary to man, 74 
 Vegetables, production of heat in, 221 
 absorption of carbonic acid and ex- 
 halation of oxygen by, 17, 225 
 Vegetable parasites, 434-435 
 Vegetative functions, 27 
 Veins, 252 
 
 al3Sorption by, 131 
 action of valves in, 253 
 motion of blood through, 252-254 
 rapidity of circulation in, 254, 255 
 omphalo-mesenteric, 567 
 umbilical, 570 
 vertebral, 573 
 Vense cavse, formation of, 574-575 
 
 position of, in foetus, 581 
 Vena azygos, superior and inferior, 
 
 formation of, 575 
 Venous system, development of, 573 
 Ventricles of heart, single in fish and 
 reptiles, 230-231 
 double in birds and mammalians, 
 
 232 
 situation of, 233 
 
 contraction and relaxation of, 239 
 elongation during contraction, 240 
 muscular fibres of, 242 
 Vernix caseosa, 545 
 Vertebrata, nervous system of, 318 
 Vertebrje, formation of, 493, 543 
 Vesicles, adipose, 58 
 pulmonary, 200 
 seminal, 462, 561 
 Vesiculse seminales, 462 
 
 formation of, 561 
 Vicarious secretion, non-existence of, 
 
 266 
 Vicarious menstruation, nature of, 266 
 Villi, of intestine, 129 
 absorption by, 130 
 of chorion, 512 
 Vision, ganglia of, 322, 323, 326, 373 
 
 nerves of, 386 
 Vital phenomena, their nature and pecu- 
 liarities, 22 
 Vitellus, 447 
 
608 
 
 INDEX. 
 
 Vitellus, segmentation of, 489 
 
 formation of, in ovary of foetus, 564, 
 565 
 Vitelline circulation, 566, 567 
 Vitelline membrane, 446 
 Vitelline spheres, 489 
 Vocal sounds, how produced, 402 
 Voice, formation of, in larynx, 402 
 
 lost, after division of spinal acces- 
 sory nerve, 403 
 Volition, seat of, in tuber annulare, 377 
 Vomiting, peculiar, after division of 
 pneumogastrics, 411 
 
 Water, as a proximate principle, 37 
 
 its proportion in the animal tissues 
 
 and fluids, 38 
 its source, 38 
 
 mode of discharge from the body, 
 39 
 Weight of organs, comparative, in newly 
 
 born infant and in adult, 590 
 White globules of the blood, 185 
 
 White globules of the blood, action of 
 acetic acid on, 186 
 sluggish movement of, in circulation, 
 257 
 White substance, of nervous system, 
 308 
 of Schwann, 308 
 of spinal cord, 320-321 
 of brain, insensible and inexcitable, 
 360 
 Withering and separation of umbilical 
 
 cord, after birth, 590 
 Wolffian bodies, 556 
 structure of, 557 
 
 atrophy and disappearance of, 560 
 vestiges of, in adult female, 563 
 WvMAN, Prof. Jeffries, on cranial nerves 
 of Rana pipiens, 388 
 
 Yellow color, of urine in jaundice, 299 
 of corpus luteum, 481 
 
 Zona pellucida, 446 
 
 THE END, 
 
CATALOGUE 
 
 OP 
 
 BIANCHARD AND LEA'S 
 MEDICAL AND SCIENTIFIC PUBLICATIONS. 
 
 TO THE MEDICAL PROFESSION. 
 
 The prices on the present catalogue are those at which our books can gene- 
 rally be furnished by booksellers throughout the United States, who can readily 
 procure any which they may not have on hand. To physicians who have not 
 convenient access to bookstores, we will forward them by mail, at these prices, 
 free of postage (as long as the existing facilities are afforded by the post office), 
 for any distance under 3,000 miles. As we open accounts only with booksell- 
 ers, the amount must in every case, without exception, accompany the order, 
 and we assume no risks of the mail, either on the money or on the books; and 
 as we deal only in our own publications, we can supply no others. Gentlemen 
 desirous of purchasing will, therefore, find it more advantageous to deal with 
 the nearest booksellers whenever practicable 
 
 BLANCHARD & LEA. 
 
 Philadelphia, July, 1859. 
 
 THE AMERICAIf MEDICAL JOURJfAL. 
 
 TWO MEDICAL PERIODICALS, FREE OF POSTAGE, 
 
 FOR FIVE DOLLARS PER ANNUM. 
 
 THE AMERICAN JOUKNAL OF THE MEDICAL SCIENCES, subject to postage, 
 when not paid for in advance - - - - - - - -$5 00 
 
 THE MEDICAL NEWS AND LIBRARY, invariably in advance - - - 1 GO 
 
 or, BOTH PERIODICALS fumished, free of postage, for Five Dollars remitted ia 
 advance. 
 
 THE AMERICAN JOURML OF THE MEDICAL SCIENCES, 
 
 Edited by ISAAC HAYS, M. D., 
 
 is published Quarterly, on the first of January, April, July, and October. Each number contains 
 about three hundred large octavo pages, appropriately illustrated, wherever necessary. It has 
 now been issued regularly for nearly forty years, and during a quarter of a century it has been 
 under the control of the present editor. Throughout this long period, it has maintained its posi- 
 tion in the highest rank of medical periodicals both at home and abroad, and has received the 
 cordial support of the entire profession in this country. Among the Collaborators will be found 
 a large number of the most distinguished names of the profession in every section of the United 
 States, rendering the department devoted to 
 
 ORIQINAL COMMUNICATIONS 
 
 full of varied and important matter, of great interest to all practitioners.* 
 
 As the aim of the Journal, however, is tocombine the advantages presented by all the different 
 varieties of periodicals, in its 
 
 * The attention of physicians throughout the Union is invited to the pages of the Journal as affording, by 
 its very extended circulation, a most eligible means for presenting their views to the profession. All ela- 
 borate articles and original inyestigations accepted and inserted by the Editor are paid for by the Publishers 
 
 1 
 
BLANCHARD AND LEA'S 
 
 REVIEW DEPARTMENT 
 
 will be found extended and impartial reviews of all important new works, presenting subjects 
 of novelty and interest, together with very numerous 
 
 BIBLIOGRAPHICAL NOTICES, 
 
 including nearly all the medical publications of the day, both in this country and Great Britain, 
 with a choice selection of the more important continental worlis. This is followed by the 
 
 QUARTERLY SUMMARY, 
 
 being a very full and complete abstract, methodically arranged, of the 
 
 IMPROVEMENTS AND DISCOVERIES IN THE MEDICAL SCIENCES. 
 
 This department of the Journal, so important to the practising physician, is the object of 
 especial care on the part of the editor. It is classified and arranged under different heads, thus 
 facilitating the researches of the reader in pursuit of particular subjects, and will be found to 
 present a very full and accurate digest of all observations, discoveries, and inventions recorded 
 in every branch of medical science. The very extensive arrangements of the publishers are 
 such as to afford the editor complete materials for this purpose, as he not only regularly receives 
 all the American medical and scientific periodicals, but also twenty or thirty of the more inri- 
 portant Journals issued in Great Britain and on the Continent, thus enabling him to present in 
 a convenient compass a thorough and complete abstract of everything interesting or important 
 to the physician occurring in any part of the civilized world. 
 
 An evidence of the success which has attended these efforts may be found in the constant and 
 steady increase in the subscription list, which renders it advisable for gentlemen desiring the 
 Journal, to make known their wishes at an early day, in order to secure a year's set with cer- 
 tainty, the publishers having frequently been unable to supply copies when ordered late in the 
 year! To their old subscribers-, many of whom have been on their list for twenty or thirty 
 years, the publisliers feel that no promises are necessary; but those who may desire for the 
 first time to subscribe, can rest assured that no exertion will be spared to maintain the Journal 
 in the high position which it has occupied for so long a period. 
 
 By reference to the terms, it will be seen that in addition to this large amount of valuable and 
 practical information on every branch of medical science, the subscriber, by paying in advance, 
 becomes entitled, without further charge, to 
 
 THE MEDICAL NEWS AND LIBRARY, 
 
 a monthly periodical of thirty-two large octavo pages. Its "News Department" presents 
 the current information of the day, while the •' Library Department" is devoted to standard 
 works on various branches of medicine. Within a few years, subscribers have thus received, 
 without expense, such books as Watson's Practice, Malgaigne's Surgery, Todd and Bow- 
 man's Physiology, West on Children, &c. While the work at present appearing in its 
 pages is 
 
 PATHOLOGIC At AND PRACTICAL OBSERVATIONS 
 
 ON DISEASES OP THE ALIMENTARY CANAL— 
 
 (ESOPHAGUS, STOMACH, C^CUM, AND INTESTINES. 
 By S. 0. HABERSHON, M. D., 
 
 Assistant Physician to and Lecturer on Materia Medica and Therapeutics at Guy's Hospital, London. 
 
 "With Illustrations on Wood, 
 (of which a more detailed account will be found on p. 42.) 
 
 Commenced in the News for January, 1858, the work will be completed during 1859. 
 Twenty pages (so arranged as to be readily detached for binding on completion) will generally 
 be devoted to it in every number, while the remainder of the periodical will contain, as hereto- 
 fore, a choice selection of important clinical reports, together with topics of immediate interest, 
 domestic and foreign. 
 
 It will thus be seen that for the small sum of FIVE DOLLARS, paid in advance, the sub- 
 scriber will obtain a Quarterly and a Monthly periodical, 
 
 EMBRACING ABOUT FIFTEEN HUNDRED LARGE OCTAVO PAGES. 
 
 mailed to any part of the United States, free of postage. 
 
 Those subscribers who do not pay in advance will bear in mind that their subscription of Five 
 Dollars will entitle them to the Journal only, without the News, and that they will be at the 
 expense of their own postage on the receipt of each number. The advantage of a remittance 
 when ordering the Journal will be thus apparent. 
 
 As the Medical News and Library is in no case sent without advance payment, its subscribers 
 will always receive it free of postage. 
 
 It should also be borne in mind that the publishers will n6w take the risk of remittances 
 by mail, only requiring, in cases of loss, a certificate from the subscriber's Postmaster, that the 
 money was duly mailed and forwarded. 
 
 ^f Funds at par at the subscriber's place of residence received in payment of subscriptions. 
 Address BLANCHARD & LEA, Philadelphia. 
 
MEDICAL AND SCIENTIFIC PUBLICATIONS. 
 NEW AND ENLARGED EDITION— Now Ready (1858). 
 
 MEDICAL LEXICON; 
 
 A DICTIONARY OF MEDICAL SCIENCE, 
 
 CONTAINING 
 
 A Concise Explanation of the Various Subjects and Terms of 
 
 ANATOMY, PHYSIOLOGY, PATHOLOGY, HYGIENE, THERAPEUTICS, PHARMA- 
 COLOGY, PHARMACY, SURGERY, OBSTETRICS, MEDICAL JURIS- 
 PRUDENCE, DENTISTRY, &c., 
 
 NOTICES OF CLIMATE AND OF MINERAL WATERS; 
 
 FORMULAE FOR OFFICINAL. EMPIRIGM. AND DIETETIC PREPARATIONS, ETC, 
 
 WITH FRENCH AND OTHER SYNONYMES. 
 
 By ROBLEf DUNGLISON, M. D., 
 
 Professor of Institutes of Medicine in tlie Jefferson Medical College, Philadelphia. 
 
 Fifteenth Edition, Revised and very greatly Enlarged, 
 
 III one very large and handsome octavo volume, of 992 douhle-columned pages, in small type; 
 strongly hoiond in leather, with raised bands. Price $4. 
 
 Especial care has been devoted in the preparation of this edition to render it in every respect 
 worthy a continuance of the very remarkable favor which it has hitherto enjoyed. The rapid 
 sale of Fifteen large editions, and the constantly increasing demand, show that it is regarded 
 by the profession as the standard authority. Stimulated by this fact, the author has endeavored 
 in the present revision to introduce whatever might be necessary "to make it a satisfactory 
 and desirable — if not indispensable — lexicon, in which the student may search without disap- 
 pointment for every term that has been legitimated in the nomenclature of the science " To 
 accomplish this, large additions have been found requisite, and the extent of the author's labors 
 may be estimated from the fact that about Six Thousand subjects and terms have been intro- 
 duced throughout, rendering the whole number of definitions about Sixty Thousand, to ac- 
 commodate which, the number of pages has been increased by nearly a hundred, notwithstand- 
 ing an enlargement in the size of the page. The medical press, both in this countrj^ and in 
 England, has pronounced the work indispensable to all medical students and practitioners, and 
 the present improved edition will not lose that enviable reputation. 
 
 The publishers have endeavored to render the mechanical execution worthy of a volume of 
 such universal use in daily reference. The greatest care has been exercised to obtain the typo- 
 graphical accuracy so necessary in a work of the kind. By the small but exceedingly clear 
 type employed, an immense amount of matter is condensed in its thousand ample pages, while 
 the binding will be found strong and durable. With all thete improvement* and enlargements, 
 the price has been kept at the former very moderate rate, placing it within the reacii of all. 
 
 This work, the appearance of the fifteenth edition 
 of which it has become our duty and pleasure to an- 
 nounce, is perhaps the most stupendous monument 
 of labor and erudition in medical literature. One 
 would hardlj' suppose after constant use of the pre- 
 ceding; editions, where we have never failed to find a 
 sufiSciently full explanation of every medical term, 
 that in this edition "about six thousand subjects and 
 terms have been added" with a careful revision and 
 correction of the entire work. It is only necessary to 
 announce the advent of this edition to make it occupy 
 the place of the preceding one on the table of every 
 medical man. as it is without doubt the best and most 
 comprehensive work of the kind which has ever ap- 
 peared. — Buffalo Med. Journ., Jan. 1S58. 
 
 The work is a monument of patient research, skilful 
 judgment, and vast physical labor, that will perpetu- 
 ate the name of the author more effectually than any 
 possible device of stone or metal. Dr. Dunglison de- 
 serves the thanks not only of the American profession, 
 but of the whole medical world. — JVorth Am. Mtdico- 
 Chir. Review, Jan. 1858. 
 
 A Medical Dictionary better adapted for the wants 
 of the profession than any other with which we are 
 acquainted, and of a character whicli places it far 
 above comparison and competition. — American Jour- 
 nal of the Medical Sciences, Jan. 1858. 
 
 AVe need only say, that the addition of 6,000 new 
 terms, with their accompanying definitions, may be 
 said to constitute a new woric by itself. We have ex- 
 amined the Dictionary attentively, and are most happy 
 to pronounce it unrivalled of its kind. The erudition 
 displayed, and the extraordinary industry which must 
 have been demanded, in its preparation and perfec- 
 tion, redound to the lasting credit of its author, and 
 have furnished us with a volume indispensable at the 
 present day, to all who would find themselves au ni- 
 veau with the highest standards of medical informa- 
 tion.— jBostore Med. and Surg. Journal, Dec. 31, 1867. 
 
 Good lexicons and encyclopedic works generally, are 
 the most labor-saving contrivances which literary men 
 enjoy: and the labor which is required to produce 
 them in the perfect manner of this example is some- 
 thing appalling to contemplate. The author tells us 
 in his preface that he has added about six thousand 
 terms and subjects to this edition, which, before, was 
 considered universally as the best work of the kind in 
 any language. — Silliman's Journal, March, 1858. 
 
 A very perfect work of the kind, undoubtedly the 
 most perfect in the English language.— i/ed. awd Surg. 
 Reporter, Jan. 1858. 
 
 The most complete authority on the subject to be 
 found in any language. — Va. Med. Journal, Feb. 185 8. 
 
BLANCHARU AND LEA'S 
 
 New and Improved Edition— Just Issued. 
 
 XN ANALYTICAL COMPEIDIDM 
 
 OF THE VARIOUS BRANCHES OF MEDICAL SCIENCE. 
 
 £ov tlje ilse arib (£?famincition of Stubcnts. 
 
 BY JOHN NEILL, M. R, 
 
 StlKGEON TO THE PENNSYLVANIA HOSPITAL, ETC., 
 AND 
 
 FRANCIS GURNEY SMITH, M. D., 
 
 PROFESSOR OF INSTITUTES OF MEDICINE IN THE PENNSYLVANIA MEDICAL COLLEGE, ETC. 
 
 A NEW EDITION, REVISED AND IMPROVED, 
 With Three Hnndred and Seventy-four Illnstrations. 
 
 /« one, very large and handsome royal l2mo. volume of vmrly 1000 pages, strongly honnd in 
 leather, with raised bands. $3. 
 
 This work presents a 
 complete and systematic- 
 outline of the whole range 
 of medical science, di- 
 vided under the headings 
 of Anatomy, Physiolo 
 GY, Surgery, Midwife- 
 ry, Chemistry, Mate- 
 ria Medica and The- 
 rapeutics, and Prac- 
 tice or Medicine. — 
 Each portion is thorough- 
 ly and appropriately il- 
 lustrated, rendering tlie 
 volume one of the cheap- 
 est as yet placed befure 
 the profession. 
 
 Lateral Operation of Lithotomy 
 
 The very flattering reception which has been accorded to this work, and the high estimate 
 placed upon it by the profession, as evinced by the constant and increasing demand which has 
 rapidly exhausted two large editions, have stimulated the authors to render the volume in its 
 present revision more worthy of the success which has attended it. It has accordingly been 
 thoroughly examined, and such errors as had on former occasions escaped observation have been 
 corrected, and whatever additions were necessary to maintain it on a level with the advance of 
 science have been introduced. The extended series of illustrations has been still further in- 
 creased and much improved, while, by a slight enlargement of the page, these various additions 
 have been incorporated without increasing the hulk of the volume. 
 
 The work is therefore again presented as eminently worthy of the favor with which it has 
 hitherto been received. As a book for daily reference by the student requiring a guide to his 
 more elaborate text-books, as a manual for preceptors desiring to stimulate their students by 
 frequent and accurate examination, or as a source from which the practitioners of older date 
 may easily and cheaply acquire a knowledge of the changes and improvement in professional 
 science, its reputation is permanently established. 
 
 The Compend of Drs. Neill and Smith is inoompara 
 bly the most valuable Tvork of its class ever published 
 in this country. Attempts have been made in various- 
 quarters to squeeze Anatomy, Physiolosiy, Surgery, the 
 Practice of Medicine, Obstetrics, Materia Medica, and 
 Chemistry into a single manual ; but the operation 
 has signally failed in the hands of all up to the advent 
 of " Neill and Smith's" volume, which is quite a mira- 
 cle of success. The outlines of the whole are admirably 
 drawn and illustrated, and the authors are eminently 
 entitled to the grateful consideration of the student 
 of every class. — N. 0. Med. and Surg. Joum., May, 1856. 
 
 This popular favorite with the student is so well 
 known that it requires no more at the hands of a 
 medical editor than the annunciation of a new and 
 improved edition. There is no sort of comparison be- 
 tween this work and any other on a similar plan, and 
 for a similar object. — Nashville Journal, of Medicine, 
 Sept. 1856. 
 
 There are but few students or practitioners of medi- 
 cine unacquainted with the former editions of this 
 unassuming though highly instructive work. The 
 whole science of medicine appears to have been sifted, 
 as the gold-bearing sands of El Dorado, and the pre- 
 cious facts treasured up in this little volume. A com- 
 plete portable library so condensed that the student 
 may make it his constant pocket companion. — Western 
 Lancet, May, 1856. 
 
 To compress the whole science of medicine in less 
 than 1,000 pases is an impossibility, but we think that 
 the book before us Approaches as near to it as is possi- 
 ble. Altogether, it is the best of its class, and has met 
 with a deserved success. As an elementary text-book 
 for students, it has been useful, and will continue to 
 be employed in the examination of private classes, 
 whilst it will often be referred to by the country prac- 
 titioner. — Va. Med. Journal, May, 1856. 
 
MEDICAL AND SCIENTIFIC PUBLICATIONS. 
 NEW AND MUCH ENLARGED EDITION— (Just Issued.) 
 
 A MANUAL OF EXAMmATIONS 
 
 UPON 
 
 ANATOMY, PHYSIOLOGY, SURGERY, PRACTICE OF MEDICINE, 
 CHEMISTRY, OBSTETRICS, MATERIA MEDICA, PHAR- 
 MACY, AND THERAPEUTICS: 
 
 TO WHICH IS ADDED A MEDICAL FORMULARY. 
 
 BY J. L. LUDLOW, M. D. 
 
 A new Edition, thoroughly modified, and greatly extended and enlarged. 
 
 With three hundred and seventy wood engravings, 
 
 1)1 one large and handsome royal VZtno. vol. of over S^Q 
 
 closely printed pages, strongly bound in leather., 
 
 price S2 50. 
 
 Crura Cerebri, ij-c. 
 
 Ampulalion of Hand. 
 
 The great popularity which this volume has always enjoyed, has stimulated the author in 
 his revision to render "it in every respect worthy of the confidence of the profession, giving rise 
 to the delay which has caused it to remain out of print for so long a time Every portion has 
 been sedulously examined, and the most recent observations and investigations introduced, 
 rendering it an accurate resume of the most improve! condition of medi^^al science. A con- 
 siderable portion has been rewritten, and entire sections on Physiology and Organic Chemistry 
 have been added, while a very complete series of illustrations has been introduced, elucidating 
 the text wherever such assistance appeared necessary or desirable. Notwithstanding an en- 
 largement of the page, these improvements have increased the size of the volume to over eight 
 hundred pages, and with the greatly improved style of mechanical execution, it may in almost 
 every respect Ise regarded rather as a new work than a new edition. 
 
 The arrangement of the volume in the form of question and answer renders it especially suit- 
 able for the office examination of students, and for those preparing for graduation. 
 
 We would recommend this book as one of the best 
 of its kind, and to every right-minded student a most 
 valuable aid in acquiring the Facts of Medical Science. 
 — South. Med. and Surg. Journ., Nov. 1S57. 
 
 In the main, we regard his work as well adapted for 
 its professed object, and that the author's claims are 
 valid. Abundant illustrations of the text are fur- 
 nished by means of wood cuts, well executed; a de- 
 cided advantage and help to the student. — Penin Jour. 
 of Med; Aug. 1857. 
 
 For the purpose for which it is intended, we do not 
 
 see but Dr Ludlow's work is as good as any other of 
 the kind. The peculiarity which distinguishes it from 
 some others of the same class, consists in the form of 
 question and answer in which it is written. We com- 
 mend it to the notice of the student who feels that he 
 must rely on such a work before being confidentially 
 closeted with his friends, the professors, previous to a 
 final departure. — A^. J. Med. Reporter, Aug. 1857. 
 
 The illustrations are good ; and the system of ques- 
 tions and answers are as well arranged as the stu- 
 dent seeking this kind of help will probably desire. — 
 Charleston Med. Jour., July, 1857. 
 
BLANCHARD AND LEA'S 
 
 New and Enlarged Edition— Just Issued. 
 
 A DICTIONARY OF TERMS USED IN MEDICINE, 
 
 AND THE COLLATERAL SCIENCES. 
 
 BY RICHARD D. HOBLYN. 
 
 A NEW AMERICAN FROM THE LAST LONDON EDITION. 
 
 Revised, with numerous Additions, 
 
 BY ISAAC HAYS, M. D., 
 
 Editor of the American Journal of the Medical Sciences. 
 
 In one large royal Vlmo. volume £>/522 closely printed douhle-cohcmn pages, leather. %\ 50. 
 
 In this volume the object of the author and editor has been to produce a work which, at an 
 exceedingly moderate price, and in a portable and convenient form, should prcf^ent all the assist- 
 ance requisite to the medical student and ordinary scientific reader. All obsolete terms have 
 been carefully excluded, and it will be found a complete and concise manual of definitions, em- 
 bodying the terms employed in medicine and its allied sciences in their present advanced condi- 
 tion. By the employment of a small but clear type, the amount of an ordinary octavo volume 
 has been condensed into its pages. 
 
 If the 'frequency with which we have referred to 
 this -volume since its reception from the publisher, 
 two or three weeks ago, tie any criterion for the future, 
 the binding will soon have to be renewed, even with 
 careful handling. We find that Dr. Hays has done 
 the profession great service by his careful and indus- 
 trious labors. The Dictionary has thus become emi- 
 nently suited to our medical brethren in this country. 
 The additions by Dr. Hays are in brackets, and we 
 believe there is not a single page but bears these in- 
 signia; in every instance which we have thus far 
 noticed, the additions are really needed and exceed- 
 ingly valuable. We heartily commend the work to 
 alfwho wish to be au courant in medical terminology. 
 — Boston Med. and Surg. Journal. 
 
 To supply the want of the medical reader arising 
 from this cause, we know of no dictionary better ar- 
 ranged and adapted than the one bearing the above 
 title. It is not encumbered with the ob.solete terms 
 of a by-gone age, but it contains all that are now in 
 use; emliracing every department of medical science 
 down to the very latest date. The volume is of a con- 
 venient size to be used by the medical student, and 
 yet large enough to make a respectable appearance in 
 the library of a physician. — yVesta-n Lancet. 
 
 Hoblyn's Dictionary has long-been a favorite with 
 us. It is the best book of definitions we have, and 
 ought always to be upon the studeat'a table. — South- 
 ern Med. mid Surg. Journal. 
 
 WILSON'S DISSECTOR— New Edition, just issued. 
 
 THE DISSECTOR'S MANUAL 
 
 OF PRACTICAL AND SURGICAL ANATOMY. 
 
 BY ERASMUS WILSOX, F. R. S., 
 
 Author of "A System of Human Anatomy." 
 
 Third American from the 
 last and Revised Lon- 
 don Edition. 
 
 ILLUSTR.^TED WITH 
 
 144 Engravings on Wood. 
 
 EDITED BY 
 
 WILLIAM HUNT. M.D., 
 
 Demonstrator of Anatomy in 
 the University of Penn'a 
 
 In one large and handsome 
 
 royal 12tno. volume of 
 
 58-4 pages. 
 
 Bound in leather, $2, 
 
 The modifications and additions which 
 this work has received in again passing 
 through the hands of the author are 
 sufficiently indicated by the fact that 
 the present edition contains nearly one- 
 half more matter than the preceding, 
 while the series of illustrations ha* 
 been increased in extent and greatly 
 improved in character. By the em- 
 ployment of a smaller type, these addi- 
 tions have been accommodated with- 
 out a correspondnig enlargement in 
 the size and price of the volume, and 
 it is again presented as fully worthy a 
 continuance of the favor which it has 
 heretofore enjoyed as a sound practical 
 guide to the study of anatomy. 
 
MEDICAL AND SCIENTIFIC PUBLICATIONS. 
 
 A NE-W AMERICAN DISSECTOR— (Just Issued). 
 
 THE PEACTIOAL ANATOMIST; 
 
 OR, 
 
 THE STUDENT'S GUIDE IN THE DISSECTING-ROOM. 
 BY J. M. ALLEN, M. D., 
 
 Late Professor of Anatomy in the Pennsylvania Medical College. 
 
 SMitlj 26*6^ Illustrations. 
 
 In 07ie large and very hatidsomi', royal 12mo. volume of 632 pages, leather, $2 25. 
 
 The very large number of elaborate illusira- 
 lions with which this woric abounds, serves to 
 render the verbal details easy of comprehen- 
 sion, showing the student what to examine, 
 and where and how to look for it, while the 
 long experience of the author as a teacher of 
 anatomy, has given him a familiarity with the 
 wants of students, and has shown him the 
 best modes of obviating or relieving the difli- 
 cullies which present themselves in the pro- 
 gress of dissection. As adapted to the course 
 pursued in our colleges, and as containing am- 
 ple practical directions and instructions, in ad- 
 dition to the anatomical details presented, it, 
 therefore, possesses claims to the immediate 
 attention of teachers and students. 
 
 It is a very convenient manual, and by its ar- 
 rangement, is well adapted to the study of practical 
 anatomy. — N'. Y. Journ. of Medicine. 
 
 We think it admirably arranged for rendering aid 
 to the student in prosecuting dissections. Its illus- 
 trations are generally accurately drawn and highly 
 useful. It will, doubtless, rank among the best 
 guides in the study of practical anatomy that are 
 now before the profession. — N. W. Med. and Surg. 
 Journal, Jan. 1857. 
 
 We are greatly pleased with Prof Allen's little 
 work. We handed our copy to a friend, who is more 
 particularly engaged in Practical Anatomy, for his 
 careful examination and opinion ; he reports it " the 
 very best dissector yet produced." The arrangement 
 is clear, concise, and convenient; its size is satisfac- 
 tory — full enough for all the purposes of the dissect- 
 
 ins-rorm, and yet, not prolix or bulky. It is beautifully illustrated— perhaps much the most so of any 
 
 dissector yet published. — Cincinnati Med. Observer. 
 
 Arteries in the Groin. 
 
 SPECIAL ANATOMY AND HISTOLOGY 
 
 BY WILLIAM E. HORNER, M. D , 
 
 Late Professor of Anatomy in the University of Pennsylvania 
 
 3£i5tlt anij EmproiitlJ B&ition. 
 
 I?i two large and handsome octavo volumes of over one 
 thousand pages, 
 
 With more than 300 beautiful Illustrations. 
 
 Extra Cloth, $6. 
 
 This work has so long occupied the position ot 
 a standard text-book and work of reference among 
 anatomists, that the present edition, fully revised 
 and thoroughly brought up by the author shortly 
 before his death, cannot fail to maintain its distin- 
 guished reputation. 
 
 Os Femoris macerated in acid. 
 
BLANCHAUD AND LEA'S 
 
 THE STUDENT'S TEXT-BOOK OF ANATOMY. 
 
 New and much enlarged edition — Just Ready (1858). 
 
 In one large 
 
 and exquisitely printed 
 
 octavo Yolume, 
 
 ■with 
 
 three hundred and ninety-seven 
 
 beautiful 
 
 engravings on wood, 
 
 and 
 
 more than 600 large pages. 
 
 Price, in leather, 
 
 $3 25. 
 
 Saphenous opening m the Fascia Lata. 
 
 A SYSTEM OF HUMAN ANATOMY. 
 
 GENERAL AND SPECIAL. 
 
 BY ERASMUS WILSON, F. R. S, 
 
 Author of " The Dissector's Manual," " A Treatise on Diseases of the Skin," &c. 
 
 A New and Revised American, from the last and enlarged English Edition. 
 
 Edited by W. H. GOBRECHT, M. P., 
 
 Professor of Anatomy in the Philadelphia College of Medicine, &c. 
 
 The publishers trust that the well-earned reputation so long 
 enjoyed by this work will be more than maintained by the pre- 
 sent edition. Besides a very thorough revision by the author, 
 it has been most carefully examined by the editor, and the 
 efforts of both have been directed to introducing everything 
 which increased experience in its use has suggested as desira- 
 ble to render it a complete text- book for those seeking to obtain 
 or to renew an acquamtance with Human Anatomy. The 
 amount of additions which it has thus received may be esti- 
 mated from the fact that the present edition contains over one- 
 fourth more matter than the last, rendering a smaller type and 
 an enlarged page requisite to keep the volume within a con- 
 venient size. The author has not only thus added largely to 
 the work, but he has also made alterations throughout, where- 
 ver there appeared the opportunity of improving the arrange- 
 ment or style, so as to present every fact in its most appropri- 
 ate manner, and to render the whole as clear and intelligible 
 as possible. The editor has exercised the utmost caution to obtain eniire accuracy in the text, 
 and has largely increased the number of illustrations, of which there are about one hundred and 
 fifty more in this edition than in the last, thus bringing distinctly before the eye of the student 
 everything of interest or importance. 
 
 The publishers have felt that neither care nor expense should be spared to render the external 
 finish of the volume worthy of the universal favor with which it has been received by the Ame- 
 rican profession, and they have endeavored, consequently, to produce in its mechanical execu- 
 tion, an improvement corresponding with that which the text has enjoyed. It will therefore be 
 found one of the handsomest specimens of typography as yet produced in this country, and in 
 all respects suited to the office table of the practitioner, notwithstanding the exceedingly low 
 price at which it has been placed. 
 
 Portion of one of Peyer''s Glands. 
 
 It is therefore at the expense of some struggle with 
 our predilections that we find ourselves called upon 
 to recognize the merits of a successor to our earlier 
 companion and guide. The struggle over, we are con- 
 strainea to declare that the edition of 1858 is a vast 
 improvement upon all others. This is, in one sen- 
 tence, the best edition of the best teaching anatomy 
 now extant. — Nashville Mrmthly Record, Nov. '58. 
 
 The great practical value of Wilson's Anatomy, as a 
 
 manual for the student, the practitioner, and for all 
 who desire to become acquainted with the subject, ia 
 too well attested by the unprecedented success of the 
 work, and the universal verdict in its favor, to render 
 recommendation necessary. We have ever commend- 
 ed Wilson's Anatomy, without hesitation or reserve, 
 to students of medicine, and the present edition only 
 increases our approbation. — Southern Med. and Surg. 
 Journal, Nov. 1858. 
 
MEDICAL AND SCIENTIFIC PUBLICATIONS 
 
 NEW AND MAGNIFICENT ANATOMICAL TEXT-BOOK— (Now Ready.) 
 
 ANATOMY, DESCRIPTIVE AND SURGICAL. 
 
 BY HENRY GRAY, P. K. S., 
 
 Lecturer on Anatomy at St. George's Hospital, Loudon, &c. 
 
 The Drawings by H. V. CARTER, M. D., 
 
 Late Demonstrator of Anatomy at St. George's Hospital. 
 
 THE DISSECTIONS JOINTLY BY THE AUTHOR AND DR. CARTER. 
 
 In 07ie splendid imperial octavo volume of about 800 very large pages, with 363 large and elabo- 
 rate engravings on wood. Price in, extra cloth, $6 25; in leather, raised bands, $7. 
 
 The author has endeavored in this work to cover a more extended range of subjects than is 
 customary in the ordinary text-books, by giving not only the details necessary for the student, 
 but also the application of those details in the practice of medicine and surgery, thus rendering 
 it not only a guide for the learner, but an admirable work of reference for the active practitioner. 
 The engravings form a special feature in the work, many of them being the size of nature, 
 nearly all original, and having the names of the various parts printed on the body of the cut, in 
 place of figures of reference with descriptions at the foot. They thus form a complete and 
 splendid series, which will greatly assist the student in obtaining a clear idt a of Anatomy, and 
 will also serve to refresh the memory of those who may find in the exigencies of practice the 
 necessity of recalling the details of the dissecting-room; while, combining as it does a complete 
 Anatomical Atlas with a thorough treatise on descriptive, practical, and applied anatomy, the 
 work will be found of essential service to physicians who receive students in their offices, assist- 
 ing both teacher and pupil in laying the groundwork of a thorough medical education. 
 
 *^* The large size of many of the illustrations prevents the selection of a favorable average 
 specimen. A small one, however, is inserted to show the manner in which the lettering ac- 
 companies the cuts. It will be observed that the attachments of the muscles are indicated by 
 dotted lines. 
 
 Occipital Bone — outer surface. 
 
 As a full, systematic, and advanced treatise on 
 anatomy, combining the various merits of the vol- 
 umes of many countries, scientifically excellent, 
 and adapted to all the ■wants of the student, we are 
 not acquainted with any work in any language 
 which can take equal rank with the one before us. — 
 London Lancet, Sept. 11, ISoS. 
 
 Mr. Gray's book, in excellency of arrangement 
 and completeness of execution, exceeds any work 
 
 on anatomy hitherto published in the English lan- 
 guage, afi'ording a complete view of the structure of 
 the human body, with especial reference to practi- 
 cal surgery. Thus the volume constitutes a perfect 
 book of reference for the practitioner, demanding a 
 place in even the most limited library of the phy- 
 sician or surgeon, and a work of necessity for the 
 student to fix in his mind what he. has learned by 
 the dissecting knife from the book of nature. — The 
 Dublin Qvxirterly Journal of Med. Sei., JNov. 1S58. 
 
10 
 
 BLAN CHARD AND LEA'S 
 
 A LIBRARY ON HUMAN ANATOMY. 
 
 HUMAli AXiTOMY, 
 
 BY JONES QUAIN, M. D. 
 
 EDITED BY 
 
 RICHARD QUAIN, M. D., 
 
 WM. SHARPEY, M.D., F.R.S., 
 
 Professors of Anatomy and Physiology 
 in University College, London. 
 
 View of the Left Nasal Fossa. 
 
 jFtrst fCmwuan, from Hi jfiitl ^Lonbon JEiilioir. , 
 
 Edited by JOSEPH LEIDY, M. D., 
 
 Professor of Anatomy in the University of Pennsylvania. 
 
 Li two large arid Jiandsome octavo volumes, containing thirteen hundred pages, and five hun- 
 dred and eleven beautiful engravings on wood, bound in leather. Price %%. 
 
 It is indeed a work calculated to make an era in ana- 
 tomical study, by placing before the student every de- 
 partment of his science, with a view to the relative im- 
 portance of each; and so skilfully have the different 
 parts been interwoven, that no one who makes this work 
 the basis of his studies, will hereafter have any excuse 
 for neglecting or undervaluing any important parti- 
 culars connected with the structure of the human 
 frame; and whether the bias of his mind lead him in 
 a more especial manner to surgery, physic, or physio- 
 logy, he will find here a work at once so comprehen- 
 sive and practical as to defend him from exclusiveness 
 on the one hand, and pedantry on the other. — Monthly 
 Journal and Retrospect of the Med. Sciences. 
 
 TVe have no hesitation in recommending this treatise 
 on anatomy as the most complete on that subject in 
 the English language: and the only one. perhaps, in 
 any language, which brings the state of knowledge 
 forward to the most recent discoveries. — The Edinburgh 
 Med. and Surg. Journal. 
 
 Admirably calculated to fulfil the object for which 
 it is intended. — Prminciol Medical Journal. 
 
 The most complete Treatise on Anatomy in the 
 English language. — Edinburgh Medical Journal. 
 
 There is no work in the English language to be pre- 
 ferred to Dr. Quain's Elements of Anatomy. — London 
 Journal of Medicine. 
 
 CARPENTER'S MANUAL OE PHYSIOLOGY. 
 
 ELEMENTS 
 
 OF 
 
 physiology: 
 
 INCLUDING 
 
 PHYSIOLOGICM ANATOMY. 
 
 BY 
 
 AV. B. Carpenter, M.D.,F.R.S. 
 
 AUTHOR OF 
 
 " Human Physiology," " Compara- 
 tive Physiology," &c. 
 
 r\ Second American, from a late 
 J'-^' and Revised London edition. 
 
 -^ ' With 190 Illustrations. 
 
 In one handsome octavo volume of 
 566 pages, leather, $3. 
 
 Distribution of Olfactory Nerve. 
 
MEDICAL AND SCIENTIFIC PUBLICATIONS. 
 SMITH AND HORNER'S ANATOMICAL ATLAS. 
 
 ANATOMICAL ATLAS, 
 
 ILLUSTRATIYE OF THE STRUGTUEE 
 OF THE HUMAN BODY. 
 
 Nerves of Ampulla of the Ear. 
 
 By henry H. smith, M. D., 
 
 Professor of Surgery in the University of Pennsylvania, 
 UNDER THE SUPERVISION OF 
 
 WM. E. HORNER, M. D., 
 
 Late Professor of Anatomy in the University of Pennsylvania. 
 
 With about Six Hundred and Fifty exquisite Illustrations on Wool. 
 In one imperial octavo volume, extra cloth. Price S3. 
 
 The great advantages possessed by vrood- 
 engraving for scientific illustration, in the 
 clearness and distinctness of its minute details, 
 are fully shown in this work, containing as it 
 does, in the compass of a single convenient 
 volume, the general and special anatomy of all 
 the component parts of the body. Commencing 
 with the Bones and Ligaments, iffollows with 
 the Muscular and Dermoid Systems, the Or- 
 gans of Digestion and Generation, Respiration 
 and Ciiculation, and concludes with the Nerv- 
 ous System and the Senses. Not only is every 
 separate organ and portion of the human frame 
 thus biought distinctly and separately before 
 the eye o( the student, but he is also presented 
 with llie results of the recent microscopical 
 investigations into the minute anatomy of the 
 various tissues ; while the plan adopted, giving 
 the plate and references on the same page, en- 
 ables him to obtain a more definite impression 
 of the objects, by avoiding the annoyance and 
 interruption of turning backwards and for- 
 wards. As a specimen of art, nothing superior 
 to it has yet been produced, while the exceed- 
 ingly low rate at which it is offered, places it 
 within the reach of ever}'' member of the pro- 
 fession. To country practitioners and students 
 it will be found especially useful, as supplying 
 in a great measure the place of skeletons and 
 subjects. 
 
 The plan of this Atlas is admirable, and its execu- 
 tion superior to anything of the kind before published 
 in this country. It is a real labor-saving affair, and 
 we regard its publication as the greatest boon that 
 could be conferred on the student of anatomy. It "ivill 
 be equally valuable to the practitioner, by affording 
 him an easy means of recalling the details learned in 
 the dissecting-room, and which are soon forgotten. — 
 American Medical Journal. 
 
 Deep stated Muscles of the Hip. 
 
 THE PRINCIPAL FORMS OF THE SKELETON AND OF THE TEETH. 
 By Professor R. Owen, F. R. S , Author of "Lectures on Comparative Anatomy," &c. 
 With seventy-six beautiful illustrations, fn one handsome volume, royal 12mo., of three 
 hundred and thirty pages, extra cloth, $1 25. 
 
12 
 
 BLANC HARD AND LEA'S 
 
 Just Issued. 
 
 IN ITS RELATIONS TO 
 
 DESCRIPTIYE ANATOMY, PHYSIOLOGY, AND PATHOLOGY. 
 
 WITH FOUR HUNDRED AND THIRTY-EIGHT ILLUSTRATIONS ON WOOD. 
 
 BY E. R. PEASLEE, M. D., 
 
 Professor of Physiology and Pathology in the New York Medical College, etc. 
 
 .^v^^Tf^ 
 
 ^\^^ 
 
 C-J 
 
 .--L 
 
 - 
 
 In one 
 
 .-c 
 
 
 beautifully printed 
 octavo volume 
 of 616 pages. 
 
 
 
 Price, 
 
 ^^ 
 
 -A 
 
 in leather. 
 
 ) 
 
 
 $3 75. 
 
 '7 
 
 
 
 Insertion of Tendo Achillis hito Calcaneutn. 
 
 It embraces a library upon the topics discussed within 
 itself, and is just what the teacher and learner need Ano- 
 ther advantage, by no means to be overlooked, everything 
 of real value in the wide range which it embraces, is with 
 great skill compressed into an <octavo volume of but little 
 more than six hundred pages. We have not only the whole 
 subject of Histology, interesting in itself, ably and fully dis- 
 cussed, but what is of infinitely greater interest to the stu- 
 dent, because of greater practical value, are its relations to 
 Anatomy, Physiology, and Pathology, which are here fully 
 and satisfactorily set forth. These great supporting branches 
 of practical medicine are thus linked together, and white 
 establishing and illustrating each other, are interwoven into 
 a harmonious whole. We commend the work to students 
 and physicians generally. — Nashville Journ. of Medicine and 
 Surgery, Dec. 1857. 
 
 It far surpasses our expectation. We never conceived the 
 possibility of compressing so much valuable information into 
 so compact a form. We will not consume space with com- 
 mendations. We receive this contribution to physiological 
 science "not with vain thanks, but with acceptance boun- 
 teous." We have already paid it the practical compliment 
 of making abundant use of it in the preparation of our lec- 
 tures, and also of recommending its further perusal most 
 cordially to our alumni ; a recommendation which we now 
 extend to our readers. — Memphis Med. Recorder, Jan. 1858. 
 
 We would recommend it to the medical student and prac- 
 titioner, as containing a summary of all that is known of the 
 important subjects which it treats; of all that is contained 
 in the great works of Simon and Lehmann, and the organic 
 chemists in general. Master this one vohime, we would say 
 to the medical student and practitioner — master this 
 book and you know all that is known of the great fun- 
 damental principles of medicine, and we have no hesi- 
 tation in saying that it is an honor to the American 
 medical profession that one of its members should have 
 produced it. — St. Louis Med. and Surg. Jour., Mar., '58. 
 
 
 Ceinfnl and Detitine at root of Tooth. 
 
 This work treats of the foundation of things, and 
 deserves a careful perusal by all those who wish to be 
 respectably informed in their profession. — Ohio Med. 
 and Surg. Journal, May, 1858. 
 
MEDICAL AND SCIENTIFIC PUBLICATIONS. 
 
 13 
 
 New and Enlarged Edition — Just Issued. 
 
 Containing nearly 
 fifteen hundred large pages, 
 
 with 
 
 five hundred and thirty-two 
 
 handsome illustrations 
 
 on wood. 
 
 ,<i I 
 
 Eighth Edition, 
 
 Revised, Modified, 
 
 and Enlarged. 
 
 In two large and handsomely 
 
 printed octavo volumes, 
 
 leather, price $7. 
 
 HUMAN PHYSIOLOGY. 
 
 BY KOBLEY DUN6LIS0N, M. D.,LL.D., 
 
 Professor of Institutes of Medicine in the Jefferson Medical College, Philadelphia. 
 
 [n revising this work for its eighth appearance, the an- t 
 
 tnor has spared no labor to render it worthy a continuance 
 of the very great favor which has been extended to it by 
 the profession. The whole contents have been rearranged, 
 and to a great extent remodelled ; the investigations which 
 of late years have been so numerous and so important, 
 have been carefully examined and incorporated, and the 
 work in every respect has been brought up to a level with 
 the present state of the subject. The object of the author 
 has been to render it a concise but comprehensive treatise, 
 containing the whole body of physiological science, to 
 which the student and man of science can at all times refer 
 with the certainty of finding whatever they are in search 
 of, fully presented in all its aspects ; and on no former edi- 
 tion has the author bestowed more labor to secure this 
 result 
 
 A similar improvement will be found in the typographic- 
 al execution of the volumes, which, in this respect, are su- 
 perior to their predecessors. A large number of additional 
 ■wood-cuts have been introduced, and the series of illustra- 
 tions has been greatly modified by the substitution of many 
 new ones for such as were not deemed satisfactory. By 
 an enlargement of the page, these very considerable addi- 
 tions have been accommodated without increasing the size 
 of the volumes to an extent to render them unwieldy. 
 
 That he has succeeded, most admirably succeeded in his purpose, 
 is apparent from the appearance of an eighth edition, and well may 
 he remark iu his preface that " the reception which his undertak- 
 ings have met with has abundantly satisfied him that his labors 
 have been far from fruitless." It is now the great encyclopaedia on 
 the subject, and worthy of a place in every physician's library. — 
 Western Lancet. 
 
 Cortical Substance of Kidney . 
 
 In preparing the present edition, "no pains have 
 been spared to make the work a complete expression 
 of the science of the day." This statement our own 
 examination of the work enables us to confirm ; every 
 page of it testifying to the author's industry in cull- 
 ing from various quarters and sources all that was 
 valuable in the physiological contributions to science 
 of the last few years. The careful and scrutinizing 
 spirit exhibited by the writer when investigating 
 mooted questions, the extensive information he pos- 
 sesses of general science in almost every department, 
 and the clear and happy style in which he presents 
 his views, render his Physiology one of the most re- 
 liable and attractive works in our language. To the 
 practitioner and general reader, we can heartily recom- 
 mend it as an excellent resume of the present state of 
 physiological science. As a text-book for the student, 
 we think it has no superior in our language, and for 
 
 this object we presume it was chiefly if not expressly 
 written.— J/ed. Examiner. 
 
 The present edition the author has made a perfect 
 mirror of the science as it is at the present hour. As 
 a work upon physiology proper, the science of the 
 functions performed by the body, the student will find 
 it all he wishes.— iVasAw'He Journ. of Med. 
 
 We believe that it can truly be said, no more com- 
 plete repertory of facts upon the subject treated, can 
 anywhere be found. The author has. moreover, that 
 enviable tact at description and that facility and ease 
 of expression which render him peculiarly acceptable 
 to the casual, or the studious reader. This faculty, so 
 requisite in setting forth many graver and less attract- 
 ive subjects, lends additional charms to one always 
 fascinating.— £os<on Med. and Surg. Journal, 
 
14 
 
 BLANCHARU AND LEA'S 
 
 NEW PHYSIOLOGICAL TEXT-BOOK— (Now Ready). 
 
 HUMAN PHYSIOLOGY. 
 
 DESIGNED FOR THE USE OF 
 
 STUDENTS AND PRACTITIONERS OF MEDICINE. 
 By J. C. DALTON, Jr., M.D., 
 
 Professor of Physiology in the College of Physicians and Surgeons, New York. 
 WITH TWO HUNDRED AND FIFTY-FOUR ORIGINAL ILLUSTRATIONS. 
 
 hi one exquisitely printed octavo volume; extra cloth, $4; leather, raised bands, $4 25. 
 
 The work before us, however, in our humble judgment, is 
 precisely what it purports to be, and will answer admirably 
 the purpose for which it is intended. It is par excellence, a 
 text-book ; and the best text-book in this department that we 
 have ever seen. We have carefully read the book, and speak 
 of its merits from a more than cursory perusal. Looking back 
 upon the work we have just finished, we must say a word con- 
 cerning the excellence of its illustrations. No department is 
 so dependent upon good illustrations, and those which keep 
 pace with our knowledge of the subject, as that of physiology. 
 The wood-cuts In the work before us are the best we have ever 
 seen, and, being original, serve to Illustrate precisely what is 
 desired. — Buffalo Med. Journal, March, 1859. 
 
 A book of genuine merit like this deserves hearty praise be- 
 fore subjecting it to any minute criticism. We are not prepared 
 to find any fault with its design until we have had more time 
 to appreciate its merits as a manual for daily consultation, and 
 to weigh its statements and conclusions more deliberately. Its 
 excellences we are sure of; its defects we have yet to discover. 
 It is a work highly honorable to its author; to his talents, his 
 industry, his training ; to the institution with which he is con- 
 nected, and to American science. — Boston Med. and Surgical 
 Journal, Feb. 24, 1859. 
 
 A new book and a first-rate one; an original book, and one 
 which cannot be too highly appreciated, and which we are 
 proud to see emanating from our country's press. It is by an 
 author who, though young, is considerably famous for physio- 
 logical research, and who in this work has erected for himself 
 an enduring monument, a token at once of his labor and his 
 success. — Nashville Medical Journal, March, 1859. 
 
 Throughout the entire work, the definitions are clear and 
 precise, the arrangement admirable, the argument briefly and 
 well stated, and the style nervous, simple, and concise. Sec- 
 tion third, treating of Reproduction, is a monograph of unap- 
 proached excellence upon this subject, in the English tongue. 
 For precision, elegance and force of style, exhaustive method 
 and extent of treatment, fulness of illustration and weight of 
 personal research, we know of no American contribution to 
 medical science which surpasses it, and the day is far distant 
 when its claims to the respectful attention of even the best in- 
 formed scholars will not be cheerfully conceded by all acquaint- 
 ed with its range and depth. — Charleston Med. Journal, May, 
 1859. 
 
 A new elementary work on Human Physiology lifting up its 
 voice in the presence of late and sturdy editions of Kirke's, 
 Carpenter's, Todd and Bowman's, to say nothing of Dungli- 
 son's and Draper's, should have something superior in the 
 matter or the manner of its utterance in order to win for itself 
 deserved attention and a name. That matter and that manner, 
 after a candid perusal, we think distinguish this work, and we 
 are proud to welcome it not merely for its nativity's sake, but 
 for its own intrinsic excellence. Its language we find to be 
 plain, direct, unambitious, and falling with a just conciseness 
 on hypothetical or unsettled questions, and yet with suflicient 
 fulness on those living topics already understood, or the path 
 to whose solution is definitely marked out. It does not speak 
 exhaustively upon every subject that it notices, but it does 
 speak suggestively, experimentally, and to their main utilities. 
 Into the suliject of Eeproduction our author plunges with a 
 kind of of loving spirit. Throughout this interesting and ob- 
 scure department he is a clear and admirable teachei', some- 
 times a bi'illiant leader. — Am. Med. Monthly, May, 1859. 
 
 We give this book of Dr. Dalton's a most hearty welcome; 
 may we have many more as" deserving from American pens. 
 It exhibits great experimental investigation and arduous labor, 
 sure evidences of devotion to science and professional pride. 
 The work is thoroughly up with the progress of Physiology, 
 
 Diagram, of the Circulation. 
 
 and has an attraction, presented by no similar book, 
 of narration of recent opinions and experiments 
 accompanied with illustrations. We will take plea- 
 
 sure, not to say pride, in recommending this work 
 as a text-book to our next class. — Savannah Jour- 
 nal of Medicine, May, 1S59. 
 
MEDICAL AND SCIENTIFIC PUBLICATIONS. 
 
 15 
 
 Now Complete. 
 
 TH E 
 
 PHYSIOLOGICAL ANATOMY AND PHYSIOLOGY OF MAN. 
 
 BY EGBERT BENTLEY TODD, M. D., F. R. S., 
 
 Professor of Physiology in King's College, London, &c. 
 AND 
 
 WILLIAM BOWMAN, F.R.S., 
 
 Demonstrator of Anatomy in King's College, London. 
 WITH TWO HUNDRED AND NINETY-EIGHT BEAUTIFUL ILLUSTRATIONS ON WOOD. 
 
 Complete in one very handsome octavo volume, of over 900 large pages, leather, p)rice $4 50. 
 
 TransKtrse Section of Human Spleen. 
 
 The very great delay which has occurred in the completion of this work has arisen from the 
 desire of the authors to verify by their own examination the various questions and statements 
 presented, thus rendering the work one of peculiar value and authority. By the wideness of 
 its scope and the accuracy of its facts it thus occupies a position of its own, and becomes neces- 
 sary to all physiological students. 
 
 1^° Gentlemen who have received portions of this work, as published in the "Medical News 
 AND Library," can now complete their copies, if immediate application be made. It will be 
 furnished as follows, free by mail, in paper covers, with cloth backs. 
 
 Parts I., II., III. (pp. 25 to 552), $2 50. 
 
 Part IV. (pp. 553 to end, with Title, Preface, Contents, &c.), $2 00. 
 
 Also, 
 Part IV., Section II. (pp. 725 to end, with Title, Preface, Contents, &c.), f 1 25. 
 
 In the present part (third) some of the most difficult 
 subjects in anatomy and physiology are handled in 
 the most masterly manner. Its authors have stated, 
 that this work was intended '• for the use of the stu- 
 dent and practitioner in medicine and surgery," and 
 we can recommend it to both, confident that it is the 
 most perfect work of its kind. We cannot conclude 
 without strongly recommending the present work to j 
 all classes of our readers, recognizing talent and depth 
 of research in every page, and believing, as we do, 
 that the diffusion of such knowledge will certainly 
 tend to elevate the sciences of medicine and surgery. 
 — Dublin Quarterly Journal of Medical Sciences. 
 
 It is highly creditable to the authors of this work, 
 that, to the exclusioQ of theory and speculation,.kjaown 
 
 anatomical facts, many of which are the fruits of their 
 own careful and laborious investigations in micro- 
 scopic anatomy, are made to serve as the foundations 
 for most of their physiological deductions. The course 
 pursued throughout the work is strictly in accordance 
 with this view. Afull description of the miuute struc- 
 ture, constitution, and development of an organ or 
 tissue, precedes, always, and is made the basis of con- 
 clusions with regard to its functions; physiological 
 views of their own, and of others, are fairly and can- 
 didly given, but none are recommended as worthy of 
 being received and adopted, excepting such as are 
 strictly in accordance with anatomical facts. — IlUnnis 
 and Indiana Medical and Surgical Journal. 
 
16 
 
 BLANCHARD AND LEA'S 
 
 THE STUDENT'S MANUAL— New Edition (Just Issued). 
 
 MANUAL OF PHYSIOLOGY. 
 
 BY WILLIAM SENHOUSE KIRKES, M. D., 
 
 Demonstrator of Morbid Anatomy at St. Bartholomew's Hospital, London. 
 
 E nth gtrntri'tart, from t^t S^fjirlr anli S^tbistli 3Lonit)on HE&ilion. 
 With numerous additional Illustrations, 
 
 MAKING ABOUT TWO HUNDRED IN ALL. 
 
 In one large and havclnome royal Ylmo. volume of nearly six hnndred pages, leather, $2. 
 
 Ciliary Epiihelizon of the Trachea 
 
 Blood Crystals of the Guinea-Pig 
 
 In again passing this work through his hands, the author has endeavored to render it a correct 
 exposition of the present condition of the science, making snchaherations and additions as have 
 been dictated by further experience, or as the progress of investigation has rendered desirable. 
 In every point of mechanical execution the publishers have sought to make it superior to former 
 editions, and at the very low price at which it is offered, it will be found one of the handsomest 
 and cheapest volumes before the profession. 
 
 In making these improvements, care has been exercised not to increase its size, thus main- 
 taining its distinctive characteristic of presenting within a moderate compass a clear and con- 
 nected view of its subjects, sufficient for the wants of the student. 
 
 A few notices of tlie former editions are appended. 
 
 In the present edition, the Manual of Physiology- 
 has been brought up to the actual condition of the 
 science, and fully sustains the reputation which it has 
 already so deservedly attained. We consider the 
 work of MM. Kirkes and Paget to constitute one of 
 the very best handbooks of Physiology we possess — 
 presenting just such an outline of the science, com- 
 prising an account of its leading facts and generally 
 admitted principles, as the student requires during 
 his attendance upon a course of lectures, or for refer- 
 ence whilst preparing for examination. — Am. Medical 
 Journal. 
 
 We need only say, that, without entering into dis- 
 cussions of unsettled questions, it contains all the 
 recent improvements in this department of medical 
 science. For the student beginning this study, and 
 
 the practitioner who has but leisure to refresh his 
 memory, this book is invaluable, as it contains all 
 that it is important to know, without special details, 
 which are read with interest only by those who 
 would make a specialty, or desire to possess a critical 
 knowledge of the subject. — Charleston MedicalJournal. 
 
 One of the best treatises that can be put into the 
 hands of the student. — London Medical Gazette. 
 
 Particularly adapted to those who desire to possess 
 a concise digest of the facts of Human Physiology. — 
 Biiiisk and Foreign Med.-Cldrurg. Review. 
 
 We conscientiously recommend it as an admirable 
 " Handbook of Physiology." — London Journal of Medi- 
 cine. 
 
 AN ESSAY TOWARDS A CORRECT THEORY OF THE NERVOUS SYSTEM. By 
 John Harrison, M. D. In one octavo volume, 292 pages. $1 50. 
 
MEDICAL AND SCIENTIFIC PUBLICATIONS. 
 
 17 
 
 New and Revised Edition— (Just Issued.) 
 
 In one largo and 
 
 very beautiful octavo volume 
 
 of nine hundred large 
 
 and closely printed pages, 
 
 with nearly 
 
 three hundred illustrations 
 
 on stone and wood, 
 
 strongly bound in leather, with 
 
 raised bands, 
 
 price $4 25. 
 
 Section of Placenta. 
 
 PRINCIPLES OF HUMAN PHYSIOLOGY, 
 
 "WITH THEIE CHIEF APPLICATIONS TO 
 
 PSYCHOLOGY, PATHOLOGY, THERAPEUTICS, HYGIENE, AND FORENSIC MEDICINE. 
 BY WILLIAM B. CARPENTER, M.D., F.R.S., 
 
 Examiner in Physiology and Comparative Anatomy in the University of London, &c. 
 A NEW AMERICAN FROM THE LAST LONDON EDITION. 
 
 Edited, with Additions, by FRANCIS GURNEY SMITH, M. D., 
 
 Professor of the Institutes of Medicine in the Pennsylvania Medical College, &c. 
 
 In the preparation of this new 
 edition, the author has spared no 
 labor to render it, as heretofore, 
 a complete and lucid exposition 
 of the most advanced condition 
 of its important subject. The 
 amount of the additions required 
 to effect this object thoroughly, 
 joined to the former large size of 
 the volume, presenting objections 
 arising from the unwieldy bulk 
 of the work, he has omitted all 
 those portions not bearing direct- 
 ly upon Human Physiology, de- 
 signing to incorporate ihem in his 
 forthcoming Treatise on Gene- 
 ral Physiology As a full and 
 accurate text-book on the Phy- 
 siology of Man, the work in its 
 present condition therefore pre- 
 sents even greater claims upon 
 the student and physician than 
 those which have heretofore won for it the very wide and distinguished favor which it has so 
 long enjoyed. The additions of Prof. Smith wi'll be found to supply whatever may have been 
 wanting to ihe American student, while the introduction of many new illustrations, and the most 
 careful mechanical execution, render the volume one of the most attractive as jet issued. 
 
 Hand of Man compared with that of Orang 
 
 The most complete exposition of physiology which 
 any language can at present give. — Brit, and For. 
 JJed.-Chirurg. Review. 
 
 The most complete work on the science in our lan- 
 guage. — Am. Med. Journal. 
 
 2 
 
 The greatest, the most reliable, and the best book 
 on the subject which we know of in the English lan- 
 guage. — Stethoscope. 
 
 A complete cyclopsedia of this branch of science. — 
 N. T. Med. Tijnes. 
 
18 
 
 BLANCHARD AND LEA'S 
 
 A new American, from the last and revised London Edition. 
 
 lu one large 
 and very handsome 
 
 octavo volume 
 of seven hundred and fifty- 
 two pages, 
 illustrated with 
 three hundred and nine 
 beautiful wood engravings. 
 Price, in extra cloth, $4 80 ; 
 
 Leather, with raised bands, \ 
 
 $5 25. 
 
 Circulatory A'pjiaratus of Pinna. 
 
 PRINCIPLES OF 
 
 COMPARATIVE PHYSIOLOGY. 
 
 BY WILLIAM B. CARPENTER, M.D., F.R.S., 
 
 Author of " Human Physiology," "The Microscope and its Revelations," &c. 
 
 Thoroughly brought up by the author to the date of publication, this work will be found to 
 fully maintain its exalted reputation as a complete and trustworthy guide to all parts of its in- 
 tricate and interesting subject. The student may therefore rely on finding in it a lucid exposi- 
 tion of Comparative Physiology in its most recent aspect, while every effort has been made to 
 render the mechanical and artislical execution of the volume worthy of its scientific character. 
 
 This hook should not only be read but thoroughly- 
 studied by every member of the profession. None are 
 too wise or old, to be beneiited thereby. But espe- 
 cially to the younger class would we cordially com- 
 mend it as best fitted of any work in the English 
 language to qualify them for the reception and com- 
 prehension of those truths which are daily being de- 
 veloped in physiology. — Medical Counsellw. 
 
 Without pretending to it, it is an Encyclopedia of 
 the subject, accurate and complete in all respects — a 
 truthful reflection of the advanced state at which the 
 science has now arrived. — Dublin Quarterly Journal of 
 Uedical Science. 
 
 A truly magnificent work — in itself a perfect phy- 
 siological study. — ManJdng's Abstract. 
 
 This work stands without its fellow. It is one few 
 
 men in Europe could have undertaken ; it is one no 
 man, we believe, could have brought to so successful 
 an issue as Dr. Carpenter. It required for its produc- 
 tion a physiologist at once deeply read in the labors 
 of others, capable of taking a general, critical, and 
 unprejudiced view of those labors, and of combining 
 the varied, heterogeneous materials at his disposal, so 
 as to form an harmonious whole. We feel that this 
 abstract can give the reader a very imperfect idea of 
 the fulness of this work, and no idea of its unity, of 
 the admirable manner in which material has been 
 brought, from the most various sources, to conduce to 
 its completeness, of the lucidity of the reasoning it 
 contains, or of the clearness of language in which the 
 whole is clothed. Not the profession only, but the 
 scientific world at large, must feel deeply indebted to 
 Dr. Carpenter for this great work. It must, indeed, 
 add largely even to his high reputation. — Med. Times. 
 
MEDICAL AND SCIENTIFIC PUBLICATIONS. 
 
 19 
 
 A MANUAL FOR THE MICROSCOPE— (Lately Published.) 
 
 THE MICROSCOPE AND ITS REVELATIONS. 
 
 BY WILLIAM B. CARPENTER, M. D., F. R. S., 
 
 Author of " Human Physiology," " Comparative Physiology," &e. 
 WITH AN APPENDIX CONTAINING 
 
 THE APPLICATIONS OF THE MICROSCOPE TO CLINICAL MEDICINE, 
 BY F. GURNEY SMITH, M. D., 
 
 Professor of Institutes of Medicine in the Pennsylvania Medical College, &a. 
 
 Illustrated with Four Hundred and Thirty-four exquisite Wood Engravings. 
 
 In one large and very handsome octavo volume of 724 pages' Price, iri extra cloth, $4 ; in 
 
 leather, f4 50. 
 
 liiJ -^ 
 
 Smith and Beck''s Student''s Microscope. 
 
 Fungoid Vegetation in Stomach of Passidiis. 
 
 To the student of physiological and micro- 
 scopic science, this work may be regarded as 
 an indispensable handbook. Commencing with 
 a history of the instrument, it proceeds with an 
 elaborate description of all the more useful and 
 improved forms of the microscope as at present 
 employed, and their comparative values for dif- 
 ferent'purposes, together with their accessories 
 and the various implements facilitating their 
 use. This is followed by minute directions for 
 the prosecution of microscopic research, em- 
 bracing not only the use of the instrument, but 
 all the necessary manipulations for the prepara- 
 tion of objects of various kinds. After thus 
 
 showing how to use the microscope, the author proceeds to indicate what has been done by its 
 assistance, losing no opportunity of pointing out what remains for investigation, and of indicating 
 the directions in'which further explorations will be most likely to lead to important results. In 
 carrying out this plan a series of chapters is given, commencing with the minute vegetable 
 forms and protophyta, and terminating with the vertebrata, thus embodying a general view of 
 the microscopic structure of all organized beings. Chapters are also devoted to the mineral 
 kingdom, and to the applications of the microscope to geology. In the Appendix, Dr. Smith 
 has presented a condensed but thorough sketch of the uses of the microscope in the prosecution 
 of clinical diagnosis, with an account of the principal microscopes manufactured in this country. 
 The volume throughout is profusely illustrated : and is printed in the handsomest manner, 
 forming one of the most creditable specimens of art as yet issued in this country. 
 
 The preeminent reputation of Dr. Carpenter as a physiologist, a microscopist, and a teacher, 
 points him out as especially fitted to produce a M'ork serving as an introduction for the beginner, 
 and as a reference book for the advanced student. 
 
 Although originally not intended as a strictly I a complete and satisfactory collection of microscopic 
 medical work, the additions hy Prof. Smith give it a facts bearing upon physiology and practical medicine 
 positive claim upon the profession, for which we douht | as is contained in Prof Smith's appendix ; and this of 
 not he will receive their sincere thanks. Indeed, we 1 itself, it seems to us, is fully worth the cost of tbe 
 know not where the student of medicine will find such volume.— XoMwrnZfe Medical Review, Nov. 1856. 
 
20 
 
 BLANCHARD AND LEA'S 
 
 A LIBRARY OF ZOO-CHEMICAL SCIENCE-(Just Issued.) 
 
 .y-^o 
 
 
 Blood Crystals of Human Venous Blood. 
 
 Urinary Deposit of Triple Phosphate, in Paralysis. 
 
 PHYSIOLOGICAL CHEMISTRY. 
 
 BY PROFESSOR C. G. LEHMANN. 
 
 Translated from the Second Edition by GEORGE E. DAY, M.D., F.R. S., &c. 
 Edited by R. E. ROGERS, M. D., 
 
 Professor of Chemistry in the Medical Department of the University of Pennsylvania, &c. 
 
 With Illxtstrations selected feom Funke's "Atlas of Physiological Chemistry," 
 
 AND AN APPENDIX OF PLATES. 
 
 Complete in two large and handsome octavo volumes of ahoiit 1200 pages, with nearly 200 
 Illustrations. Extra cloth, $6. 
 
 This o-reat work, universally acknowledged as the most complete and authoritative exposition 
 of the principles and details of Zoochemistry, in its passage through the press, has received 
 from Professor Rogers such care as was necessary to present it in a correct and reliable form. 
 To such a work additions were deemed superfluous, but several years having elapsd between 
 the appearance in Germany of the first and last volume, the latter contained a supplement, em- 
 bodving numerous corrections and additions resulting from the advance o^ the science. These 
 have all been incorporated in the text in their appropriate places, while the subjects have been 
 still further elucidated by the insertion of illustrations from the Atlas of Dr. Otto Funke. With 
 the view of supplying the student with the means of convenient comparison, a large number 
 of wood-cuts, from works on kindred subjects, have also been added in the form of an Appendix 
 of Plates. 
 
 Within the last few years the vast extension of the positive facts of science has demonstrated 
 the connection and interdependence of the various branches of knowledge. The lines of de- 
 marcation have gradually disappeared, and the student of physiology can no longer confine him- 
 self to the scalpel and the microscope. At this time, therefore, a work like the present becomes 
 a necessity to all earnest inquirers mto the processes of nature, accumulating as it does, to the 
 development of Physiology, all the aids afforded by the cognate departments of science in their 
 most recent and advanced condition. 
 
 The most important contribution as yet made to 
 Physiological Chemistry— jtni.JoMrraaZ Med. Sciences. 
 
 The present volumes belong to the small class of 
 medical literature which comprises elaborate works 
 of the highest order of vaeriV.— Montreal Med. Chro- 
 nicle. 
 
 Already well known and appreciated by the scien- 
 tific world, Professor Lehmann's great work requires 
 no laudatory sentences, as, under a new garb, it is now 
 presented to us. The little space at our command 
 would ill suffice to set forth even a small portion of 
 its excellences. To all whose studies or professional 
 duties render the revelations of Physiological Che- 
 
 mistry at once interesting and essential, these volumes 
 will be indispensable. Highly complimented by Euro- 
 pean reviewers, sought for with avidity by scholars of 
 every nation, and admirably written throughout, it is 
 sure to win a welcome and to be thoroughly studied. 
 — Boston Med. and Surg Journal. 
 
 The work of Lehmann stands unrivalled as the most 
 comprehensive book of reference and information ex- 
 tant on every branch of the subject on which it treats. 
 — Edinburgh Monthly Journal of Medical Sciences. 
 
 All teachers must possess it, and every intelligent 
 physician ought to do hkewise..— Southern Med. and 
 Surg. Journal. 
 
MEDICAL AND SCIENTIFIC PUBLICATIONS. 
 
 21 
 
 HANDBOOK OF CHEMICAL PHYSIOLOGY— (Just Issued.) 
 
 MANUAL OF CHEMICAL PHYSIOLOGY. 
 
 J^rom tljc djicrman of 
 PROFESSOR C. a. LEHMANN, M. D. 
 
 TRANSLATED, WITH NOTES AND ADDITIONS 
 
 BY J. CHESTON MORRIS, M.D. 
 
 WITH AN 
 
 INTRODUCTORY ESSAY ON VITAL FORCE, 
 
 BY SAMUEL JACKSON, M. D., 
 
 Professor of Institutes of Jledicine in the University of 
 Pennsylvania. 
 
 WITH HANDSOME ILLUSTRATIONS ON WOOD. 
 
 Ill one very neat octavo volume, of tlivee hundred and thirty- 
 four pages, extra cloth, $2 25. 
 
 Section of Skin treated intth Acetic Acid. 
 
 From Professor Jackson's Introductory Essay. 
 
 In adopting the handbook of Dr. Lehmann as a manual of Organic Chemistry for the use of 
 the students of the University, and in recommending- his original work of PhysIological Che- 
 mistry for their more mature studies, tJie high value of his researches, and the great weight of 
 his authority in that important department of medical science are fully recognized. 
 
 We have read this volume with great interest and 
 much profit, intendins: to make an epitome of its con- 
 tents for the benefit of our readers, but finding that it 
 is itself but an abridgment, which cannot easily be 
 further condensed, we are compelled to relinquish 
 that design, and terminate this notice by expressing 
 the wish that every student and practitioner in the 
 Peninsular State could be the owner of a copy of Leh- 
 mann's Chemical Physiology. — Peninsular Med. Jour- 
 nal, June, 1856. 
 
 In its more concise and simplified form this hand- 
 book of Physiological Chemistry gives the student an 
 
 opportunily of examining the vast and laborious re- 
 searches of the German physiologists in the field of 
 Zoo-Chemistry. AVe can but admire the patient labor 
 exhibited on every page. With what careful analysis 
 has every one of the organic compounds been tested 
 by the chemical forces — how carefully and yet accu- 
 rately have all the chemical laws been brought to bear 
 upon the living tissues of the human body. We are 
 well satisfied to leave the readers of this work (and 
 every one who is desirous to be familiar with modern 
 physiology should read it), to determine each one for 
 himself the important doctrine here taught — Va. Med. 
 Journal, May, 1856. 
 
 New and Improved Edition— (Just Issued.) 
 
 A PRACTICAL HANDBOOK OF MEDICAL CHEMISTRY i 
 
 BY JOHN E. BOWMAN, F. C. S., 
 
 Professor of Practical Chemistry in King's College, London. 
 
 .Sitonir Emtritan, from t^j QIf)tr& anlr 3£t£bist& HLonlJoit 35IJition. 
 
 WITH NUMEROUS ILLUSTRATIONS. 
 
 Iti 07ie neat royal Viino. volume of nearly 300 pages ; extra cloth, 
 price $1 25. 
 
 Presenting, in a condensed and convenient form, at a very low price, 
 the applications of Chemistry to the practical purposes of Clinical Me- 
 dicine, this work supplies a want which lias long been felt by the phy- 
 sician. The numerous editions which have been called for both in 
 England and this country, sufficiently attest the success with which the 
 author has carried out his plan. 
 
 Analysis of Diabetic Urine. 
 
22 
 
 BLANCHARD AND LEA'S 
 
 GRAHAM'S CHEMISTRY— Now Complete (1858.) 
 
 ELEMENTS OF INORGANIC CHEMISTRY; 
 
 INCLUDING 
 
 THE APPLICATIONS OF THE SCIENCE IN THE ARTS. 
 BY THOMAS GRAHAM, R R. S. L. and E., 
 
 Late Professor of Chemistry in University College, London, &c. 
 
 Edited by HENRY WATTS, B. A., and ROBERT BRIDGES, M.D. 
 
 SECOND AMERICAN FROM THE SECOND REVISED AND ENLARGED LONDON EDITION. 
 
 Complete in One Volume, with 233 Illustrations on Wood. 
 
 In one very large and handsome octavo volume o/850 very large pages. Price, in extra cloth, 
 $4; leather, raised lands, $4 50. 
 
 *ifc* Part II. (completing the work), from p. 431 to end, with Index, Title matter, &e., may be 
 liad separate, in stout wrappers, uncut, for binding, price $2 50, on receipt of which it will 
 be forwarded by mail, free of postage, to any address. Gentlemen desirous of completing 
 their copies are requested to apply for it without delay. 
 
 The long delay which has intervened since the 
 appearance of the first portion of this work, has 
 rendered necessary an Append ix, embodying t he 
 numerous and important investigations and dis- 
 coveries of the last few years in the subjects 
 contained in Part I. This occupies a large por- 
 tion of Part 11., and will be found to present a 
 complete abstract of the most recent researches 
 in the general principles of the science, as well 
 as all details necessary to bring the whole work 
 thoroughly up to the present time in all depart- 
 ments of Inorganic Chemistry. 
 
 It is a very acceptable addition to tlie library of stand- 
 ard books of every chemical student. Mr. Watts, well 
 known as the translator of the Cavendish Society edi- 
 tion of Gmelin's Chemistry, has made in the supple- 
 ment an able reszwne of the progress of the science since 
 the publication of the first volume. It is plain, from 
 the number and importance of the topics there dis- 
 cussed, that great progress has been made in the inter- 
 val, both in chemical physics and in general inorganic 
 chemistry. No reader of English works on this science 
 can afford to be without this edition of Prof. Graham's 
 Elements. — SillvniarCs Journal, March, 1858. 
 
 J?Vo»i Prof. 0. P. Hubbard, Dartmouth College, N. H., 
 May 20, 1S58. 
 I am impressed with the great amount and variety 
 of its contents, and its great value to chemists who 
 have not access to all the current literature of the day 
 in chemistry. Its appendix embraces a great deal of 
 recent investigation not found in any other American 
 republication. 
 
 From Professor J. L. Crawcour, New Orleans School of 
 Medicine, May 9, 1858. 
 It is, beyond all question, the best systematic work 
 on Chemistry in the English language, and I am grati- 
 fied to find that an American edition at a moderate 
 price has been issued, so as to place it within the means 
 of students. It will be the only text-book I shall now 
 recommend to my class. 
 
 From Prof. E. N. Horsford, Harvard College, April 27, 
 1858. 
 It has, in its earlier and less perfect editions, been 
 familiar to me, and the excellence of its plan and the 
 clearness and completeness of its discussions, have 
 long been my admiration. 
 
 Osmometer. 
 
 From Prof. Wolcoit Gihhs, New York Free Academy, 
 
 May 25, 1858. 
 
 The work is an admirable one in all respects, and 
 
 its republication here cannot fail to exert a positive 
 
 influence upon the progress of science in this country. 
 
 HANDBOOK OF CHEMISTRY; 
 
 THEORETICAL, PRACTICAL, AND TECHNICAL. 
 BY F. A. ABEL and C. L. BLGXAM. 
 
 WITH A PREFACE BY A. W. HOFMANN, M. D., 
 
 gLnlJ Numxrou5 Illustrations on Mooli. 
 
 In 07ie large and liandsome octavo volume of nearly 100 pages ; extra cloth, price $3 25. 
 
MEDICAL AND SCIENTIFIC PUBLICATIONS. 
 
 23 
 
 NEW AND ENLARGED EDITION— Now Ready (July 1859). 
 THE STUDENT'S MATTIJAL OP CHEMISTRY. 
 
 In one large royal 12mo. volume 
 
 of 600 pages, 
 
 with 197 illustrations on wood. 
 
 In leather, $1 65 ; 
 
 extra cloth, $1 50. 
 
 Induction Coil. 
 
 ELEMENTARY CHEMISTRY; 
 
 THEORETICAL AND PRACTICAL. 
 BY GEORGE FOWNES, F.R.S., 
 
 Late Professor of Practical Chemistry in University College, London. 
 
 Edited by ROBERT BRIDGES, M.D., 
 
 Professor of Chemistry in the Philadelphia College of Pharmacy, 
 
 jFrom li)t Stbtntf) ffni 
 
 ^thistii 
 
 .oniDn B&ition:. ,^='^r:~^. —ds^- 
 
 Gas Furnace for Organic Analysis. 
 
 The seventh edition of thi» popular manual, published a few months since in London under 
 the editorial supervision of Messrs. Benee Jones and A. W. Hoffman, received a thorough re- 
 vision which has brought it fully up to the present state of the science. The department of Or- 
 ganic Chemistry is of course the one in which the greatest amount of addition was requisite, 
 and in introducing what was necessary to render it a fair exposition of the subject in its most 
 advanced condition, care has been exercised to retain the characters ol clearness and condensa- 
 tion which have rendered the work so deservedly a favorite with all classes of students, while 
 the completeness with which all branches of the subject — Chemical Physics as well as Inor- 
 ganic and Organic Chemistry — are presented is in no way interfered with To accommodate 
 the additions, the size of the page has been enlarged, notwithstanding which the number has 
 been increased by nearly fifcy pages. The present enlarged and improved edition, presenting 
 the matter of an ordinary large octavo volume in so small a compass and at so very Iowa price, 
 will therefore, it is hoped, maintain the popularity which the work has always enjoyed with 
 both teachers and students. A few notices of previous editions are subjoined. 
 
 We know of no better text-book, especially in the 
 difficult department of organic chemistry, upon which 
 it is particularly full and satisfactory. We would re- 
 commend it to preceptors as a capital '-office book" for 
 their students who are beginners in Chemistry. It is 
 copiously illustrated with excellent wood-cuts, and 
 altogether admirably "got up." — N. J. Med. Reporter. 
 
 A standard manual, which has long enjoyed the 
 reputation of embodying much knowledge in a small 
 space. The author has achieved the difficult task of 
 condensation Avith masterly tact. His book is concise 
 without being dry, and brief without being too dog- 
 matical or general. — Virginia Med. and Surg. Journal. 
 
 We unhesitatingly recommend it to medical stu- 
 dents. — M. W. Med. and Surg. Journal. 
 
 One of the best elementary works on Chemistry ac- 
 cessible to the American and English student. — iV. Y. 
 Jownal of Medicine. 
 
 The work of Dr. Fownes has long been before the 
 public, and its merits have been fully appreciated as 
 the best text-book on Chemistry now in existence. 
 We do not, of course, place it in a rank superior to 
 the works of Brande, Graham, Turner, Gregory, or 
 Gmelin, but we say that, as a work for students, it is 
 preferable to any of them. — London Journ. of Medicine. 
 
24 
 
 BLANCHARU AND LEA'S 
 
 APPLIED CHEMISTRY. 
 
 In two 
 
 very handsome 
 
 octavo volumes, extra cloth, 
 
 containing 
 
 about one thousand pages, 
 
 and nearly 
 
 five hundred splendid 
 
 wood engravings. 
 
 Price $6, 
 
 Apparatus for Rosin Gas. 
 
 TECHNOLOGY: 
 
 OR, CHEMISTRY APPLIED TO THE ARTS AND TO MANUFACTURES. 
 
 BY PROFESSOR F. KNAPP. 
 
 EDITED, WITH NUMEROUS NOTES AND ADDITIONS, 
 
 BY DR. EDMUND RONALDS and DR. THOMAS RICHARDSON. 
 
 With American Additions by Pkof. WALTER R. JOHNSON. 
 
 The innumerable applications of chemical science to all branches of art and manufacture, 
 ender a work like the present indispensable to all practical men. The very full and accurate 
 escriptions of the most approved processes, elucidated by the very full series of beautiful illus- 
 rations, give it a value w^hich can hardly fail to be appreciated in an age and country such as this. 
 
 MEDICAL CHEMISTRY; 
 
 FOR THE USE OF STUDENTS AND THE PROFESSION. 
 
 Being a Manual of the Science, with its applications to Toxicology, 
 Physiology, Therapeutics, Hygiene, &c. 
 
 BY D. P. GARDNER, M.D., 
 
 l7i o?ie royal 12mo. volume, extra cloth, vdth ilhistrations . Price $1. 
 
 This volume possesses especial claim on the attention of the profes 
 sion as being the only work in which the subject is systematically treated 
 with a view to its bearings on medicine. The sole aim of the author 
 throughout has been to render it the Chemistry for the Medical Student. 
 
 Marsh's Test for Arsenic. 
 
MEDICAL AND SCIENTIFIC PUBLICATIONS. 
 
 25 
 
 M INTRODUCTION^ TO PRACTICAL CHEMISTRY, 
 
 INCLUDING ANALYSIS. 
 BY JOHN E. BOWMAN, 
 
 Professor of I'ractical Chemistry in King's College, 
 London, &.c. 
 
 ■With One Hundred Illustrations. 
 
 Se.ond American, from the Second and Revised 
 
 London Edition, 
 
 I?i one neat royal Ylmo. volume, extra cloth, of 300 
 pages, price $1 25. (Just Issued.) 
 
 This little work, giving in a clear, concise, and 
 elementary form such instruction as is required by 
 the student of practical chemistry, has deservedly 
 become a favorite vv'ith those for whom it is designed. 
 The author has throughout endeavored lo present the 
 simplest modes and apparatus leading to correct re- 
 sults. 
 Decantalion and Filtration. 
 
 MOHR AND REDWOOD'S PRACTICAL PHARMACY. 
 
 practicalIpharmacy. 
 
 THE AEEANGEMENTS, APPAEATTIS, AND MANIPULATIONS OF THE PHAEMACETI- 
 TICAL SHOP AND LABORATORY. 
 
 BY FRANCIS MOHR, Ph. R, 
 
 Assessor PharmacifE of the Koyal Prussian College of Medicine ; 
 
 AND THEOPHILUS REDWOOD, 
 
 Professor of Chemistry and Pharmacy to the Pharmaceutical Society of Great Britain. 
 
 Edited, ttith extensive Additions, by "WILLIAM PROCTER, Jr., 
 
 Professor of Pharmacy in the Philadelphia College of Pharmacy. 
 
 ILLUSTRATED WITH FIVE HUNDRED ENGRAVINGS ON WOOD. 
 
 In one large and very handsome octavo volume, of nearly 600 images, extra c?o<7i,^jriVe $2 75. 
 
 J". 
 
 This work will be found of great va- 
 lue, not only to apothecaries, but also to 
 physicians who live at a distance from 
 competent pharmaceutists. Compre- 
 hending, as it does, all the manipula- 
 tions and operations of preparing and 
 dispensing medicines, from the extrac- 
 tion of a stopper or the tying of a cork, 
 to the most complicated and delicate 
 processes of pharmacy, illustrated at 
 every step with a profusion of engrav- 
 ings, it may be regarded as an indispen- 
 sable assistant to the druggist and coun- 
 try practitioner, while its very moderate 
 price places it within the reach of all. 
 
 Water-bath Funnel. 
 
 It is a book, however, which will be in the hands of 
 almost every one who is much interested in pharma- 
 ceutical operations, as we know of no other publicar 
 tion so well calculated to fill a void long felt. — Medical j 
 Examiner. 
 
 This work is very full and complete, and details, in i 
 a style uncommonly clear and lucid, not only the ' 
 
 more complicated and difficult processes, but those not 
 less important ones, the most simple and common. — 
 
 Buffalo Medical Journal. 
 
 The country practitioner who is obliged to dispense 
 his own medicines, will find it a most valuable assist- 
 ant. — Monthly Journal and Metrospect. 
 
26 
 
 BLANCHARD AND LEA'S 
 
 A DISPENSATORY AND PHARMACY COMBINED.' 
 
 In one 
 
 very handsome 
 
 octavo volume, 
 
 extra cloth, 
 
 of 
 550 pnges. 
 
 With nearly 
 
 two hundred and fifty 
 
 illustrations. 
 
 Price S2 75. 
 
 Wiegand^s Powder Folder. 
 
 M INTPiODUCTION TO PRACTICAL PHARMACY. 
 
 DESIGNED AS 
 
 A TEXT-BOOK FOR THE STUDENT AND AS A GUIDE FOR THE PHY- 
 SICIAN AND PHARMACEUTIST. 
 WITH MANY FORMUL/E AND PRESCRIPTIONS. 
 BY EDWARD PARRISH, 
 
 Principal of ihe School of Practical Pharmacy, Philadelphia. 
 
 This work, while necessary to the edu- 
 cated pharmaceutist, will also be ibund of 
 the greatest importance to those practi- 
 tioners who, residing at a distance from 
 apothecaries, are called upon to dispense 
 as well as to prescribe. The author has 
 not only given a thorough outline of the 
 principles ofpharinacy and its general pro- 
 cesses, but has also presented their special 
 applications in the details of preparing all 
 the difierent classes of medicines, illustrat- 
 ed with numerous engravings of apparatus 
 and implements, which, in all cases, are 
 of the simplest description. Under the 
 different heads are contained many tables 
 and syllabi of classes of medicines, pre- 
 senting the remedies of the United States 
 Pharmacopoeia, together with many new ones, so arranged as to render their relations of easy 
 comprehension, and embodying all the more important formulae of the Pharmacopoeia, as well 
 as many others from the practice of distinguished physicians, not hitherto in print. Especial 
 notice has been taken of the numerous important remedies recently obtained from our indige- 
 nous flora, and their composition and preparation pointed out. 
 
 The long experience of the author as a teacher of pharmacy has rendered him familiar with 
 the wants of students, and entirely competent to supply them. He has accordingly descended 
 to those minutiae which so often interpose difficulties in the way of the young practitioner, who 
 has hitherto had no practical guide to point out the modes of overcoming them. 
 
 Board, Rolltr, and Punch/or Lozenges 
 
 This is a well-timed and most valuable work. It is 
 designedly adapted to meet the wants both of the 
 practical pharmaceutist, and of the physician ; and 
 to both these classes we doubt not it will prove an 
 acceptable offering There are thousands of prac- 
 titioners throughout the country who are neces- 
 sarily compelled to compound their own medicines, 
 who, however well they may be informed on the 
 subject of therapeutics, it must be acknowledged are 
 but illy instructed in the art of preparing reme- 
 dies for use. In the work now offered to the public, 
 Mr. Parrish has undertaken to supply the want of ele- 
 mentary knowledge on this subject by prepariug a 
 book containing the leading facts and principles of 
 pharmacy, presented in so simple and clear a man- 
 ner, and go well illustrated by engravings, as to be 
 perfectly intelligible to all. We take great pleasure 
 in recommending this work to our readers, and espe- 
 cially to country practitioners, as we are satisfied that 
 they will find it of essential aid, in enabling them to 
 discharge aright that difficult part of their daily task, 
 to wit: preparing and compounding their remedies. — 
 St. Louis Med. and Surg. Journal. 
 
 It is with reluctance and much regret that we are 
 compelled to give the above work only a hook notice. 
 It was our wish and intention to attempt an extended 
 analysis of its contents that our readers might judge 
 
 somewhat for themselves of its great and numerous 
 merits, but the subject matter is of such a nature as 
 to forbid anything like a review. All that we can say 
 of it is that to the practising physician and especially 
 the country physician who is generally his own apo- 
 thecary, there is hardly any book that might not better 
 be dispensed with. It is at the same time a dispensa- 
 tory and a pharmacy. — Louisville Review. 
 
 A careful examination of this work enables us to 
 speak of it in the highest terms, as being the best 
 treatise on practical pharmacy with which we are ac- 
 quainted, and an invaluable vade-mecum, not only to 
 the apothecary and to those practitioners who are 
 accustomed to prepare their own medicines, but to 
 every medical man and medical student. — Boston 
 Med. and Surg. Journal. 
 
 This is altogether one of the most useful books we 
 have seen. It is just what we have long felt to be 
 needed by apothecaries, students, and practitioners of 
 medicine, most of whom in this country have to put 
 up their own prescriptions. It bears, upon every page, 
 the impress of practical knowledge, conveyed in a 
 plain common sense manner, and adapted to the com- 
 prehension of all who may read it. No detail has been 
 omitted, however trivial it may seem, although really 
 important to the dispenser of va^HitAne.— Southern Med. 
 and Surg. Journal, 
 
MEDICAL AND SCENTIFIC PUBLICATIONS. 
 
 27 
 
 Enlarged and Improved Edition. 
 
 A UNIVERSAL FORMULARY 
 
 CONTAINING THE 
 
 METHODS OF PREPARING AND ADMINISTERING 
 
 OFFICINAL AND OTHER MEDICINES. 
 
 The whole adapted to Physicians and Pharmaceutists. 
 
 BY R. EGLESFELD GRIFFITH, M. D. 
 
 A Ne-vv Edition, carefully Revised and much Kxtended, 
 
 BY ROBERT P. THOMAS, M. D., 
 
 Professor of Materia Medica in the Philadelphia College of Pharmacy, &c. 
 
 In one 
 
 handsome octavo 
 
 volume, with 
 
 Illustrations. 
 
 Containing six 
 
 hundred and fifty 
 
 large pages, 
 
 mostly double 
 
 columns. 
 
 Price, in leather, 
 
 extra chith, $3. 
 
 Coating Pills with Gelatine. 
 
 Besides the Formulary proper, this work contains a vast amount of information indispensa- 
 ble for daily reference by the practising physician and apothecary, embracing Tables of Weights 
 and JMeasures, Specific Gravity, Temperature for Pharmaceuiical Operations, Hydrometrical 
 Equivalenis, Specific Gravities of some of the Preparations of the Pharmacopoeias, Relation 
 between different Thermometrical Scales, Explanation of Abbreviations used in Formulae, 
 Vocabulary of Words used in Prescriptions, Observations on the Management of the Sick 
 Room, Doses of Medicines, Rules for the Administration of Medicines, Management of Con- 
 valescence and Relapses, Dietetic Preparations, not included in the Formulary, List of Incom- 
 patibles, Posological Table, Table of Pharmaceutical Names which differ in the Pharmacopoeias, 
 Officinal Preparations and Directions, and Poisons. 
 
 Three complete and extended Indexes render the work especially adapted for immediate con- 
 sultation. One of Diseases and their Remedies, presents under the head of each disease the 
 remedial agents which have been usefully exhibited in it, with reference to the formulas con- 
 taining them — while another of Pharmaceutical and Botanical Names, and a very thorough 
 General Index afford the means of obtaining at once any information desired. The Formulary 
 itself is arranged alphabetically, under the heads of the leading constituents of the prescriptions. 
 
 It was a work requiring much perseverance, and 
 when published was looked upon as by far the best 
 work of its kind that had issued from the American 
 press. Prof. Thomas has certainly "improved," as 
 well as added to this Formulary, and has rendered it 
 additionally deserving of the confidence of pharma- 
 ceutists and physicians. — Am. Journal of Pharmacy. 
 
 We are happy to announce a new and improved 
 edition of this, one of the most valuable and useful 
 works that have emanated from an American pen. It 
 would do credit to any country, and will be found of 
 daily usefulness to practitioners of medicine; it is 
 better adapted to their purposes than the dispensa- 
 tories. — Southern Med. aiid Surg. Journal, 
 
 A new edition of this well-known work, edited by 
 R. P. Thomas, M. D., affords occasion for renewing our 
 commendation of so useful a handbook, which ought 
 to be universally studied by medical men of every 
 class, and made use of by way of reference by office 
 pupils, as a standard authority. It has been much 
 enlarged, and now condenses a vast amount of need- 
 ful and necessary knowledge in small compass. The 
 more of such books the better for the profession and 
 the public. — N. Y. Med. Gazette. 
 
 It is one of the most useful books a country practi- 
 
 tioner can possibly have in his possession. — Medical 
 Chronicle. 
 
 The amount of useful, every-day matter, for a prac- 
 tising physician, is really immense. — Boston Med. and 
 Surg. Journal. 
 
 This is a work of six hundred and fifty-one pages, 
 embracing all on the subject of preparing and admi- 
 nistering medicines that can be desired by the physi- 
 cian and pharmaceutist. — Western Lancet. 
 
 In short, it is a full and complete work of the kind, 
 and should be in the hands of every physician and 
 apothecary.— O. Med. and Surg. Journal. 
 
 We predict a great sale for this work, and we espe- 
 cially recommend it to all medical teachers. — Hich- 
 mond Stethoscope. 
 
 This edition of Dr. Griffith's work has been greatly 
 improved by the revision and ample additions of Dr. 
 Thomas, and is now, we believe, one of the most com- 
 plete works of its kind in any language. The additions 
 amount to about seventy pages, and no effort has been 
 spared to include in them all the recent improvements 
 which have been published in medical journals and 
 systematic treatises. A work of this kind appears to 
 us indispensable to the physician, and there is none 
 we can more cordially recommend. — iV. T. Journal of 
 Medicine. 
 
28 
 
 BLANCHARU AISID LEA'S 
 
 DUNGLISON'S THERAPEUTICS— (Just Issued). 
 
 GENERAL THERAPEUTICS 
 
 ADAPTED FOR A MEDICAL TEXT-BOOK. 
 BY ROBLEY DUNGLTSON, M. D., 
 
 Professor of Institutes of Medicine in Jefferson Medical College, Philadelphia. 
 
 WITH ABOUT 
 
 Two Hundred Illustrations. 
 
 SIXTH EDITION, 
 
 3^cbiscTJ an"D JJmjpvobeti. 
 
 I7i two very handsonne octavo vo- 
 lumes of about 11 00 pages ; 
 leather, price $6. 
 
 The constant accessions to 
 the list of remedial agents, 
 and the industry with which 
 investigations are daily made 
 in practical therapeutics, ren- 
 der a work like this one of 
 the most indispensable ad- 
 juncts to a physician's libra- 
 ry. The industry of the au- 
 thor in bringing his works up 
 to the day of publication, and 
 the rapid succession of edi- 
 tions, which enables him to 
 frequently embody the results 
 of the latest improvements 
 and discoveries, is a sufficient 
 guarantee that these volumes 
 will always be found on a level 
 with the most advanced state 
 of the subject. 
 Ricmus communis {Castor-Oil Plant.) 
 
 In this work of Dr. Dunglison, we recognize the 
 same untiring industry in the collection and embody- 
 ing of facts on the several subjects of which he treats, 
 that has heretofore distinguished him, and we cheer 
 fully point to these volumes as two of the most inte- 
 resting that we know of. In noticing the additions to 
 this edition, there is verj' little in the periodical or 
 annual literature of the profession, published in the 
 interval which has elapsed since the issue of the first, 
 that has escaped the careful search of the author. As 
 a book for reference, It is invaluable. — CharUsion 
 Medical Journal and Review. 
 
 It may be said to be the work now upon the subjects 
 upon which it treats. — Western Lancet. 
 
 The most complete and satisfactory exponent of the 
 existing state of Therapeutical Science, within the 
 moderate limits of a text-book, of any hitherto pub- 
 lished. What gives the work a superior value, in our 
 judgment, is the happy blending of Therapeutics and 
 Materia Medica as they are or ought to be taught in all 
 our Medical schools; going no further into the nature 
 and commercial history of drugs than is indispensable 
 for the medical student. This gives to the treatise a 
 clinical and practical character, calculated to benefit, 
 in the highest degree, both students and practitioners. 
 We shall adopt it as a text-book for our classes, while 
 pursuing this branch of medicine, and shall be happy 
 to learn that it has been adopted as such in all of our 
 medical institutions. — The N. Y. Journal of Medicine. 
 
 A DISPENSATORY AND THERAPEUTICAL REMEMBRANCER, Comprising the entire 
 lists of Materia Medica, with every Practical Formula contained m the three British Pharma- 
 copoeias. By John Mayne, M. D., M. R. C.S Edited, with the addition of the Formulse 
 of the United States Pharmacopoeia, by R. Eglesfeld Griffith, M. D. In one 12mo. 
 volume, extra cloth, of over 300 large pages, cloth, 75 cents. 
 
MEDICAL AND SCIENTIFIC PUBLICATIONS. 29 
 
 A NEW AND COMPLETE THERAPEUTICAL TEXT-BOOK— (To be ready in the autumn.) 
 
 THERAPEUTICS AND~MATERIA MEDICA: 
 
 A SYSTEMATIC TREATISE ON THE 
 
 HISTORY, DESCRIPTION, ACTIONS, AND USES OF MEDICINAL AGENTS. 
 
 BY ALFRED STILLE, M. D., 
 
 Late Professor of the Theory and Practice of Medicine in the Pennsylvania Med. College. 
 In two large and handsome octavo volumes of over 1500 pages. 
 
 The object which the author has kept in view in the preparation of this work has been to 
 present to the profession a complete and sy^tel■natlc treatise suited to the wants o( the practising 
 physician. He has therefore endeavored to avoid encumbering his text with details interesting 
 only to the naturalist or the dealer, and has sought to give in ihe history and description of drugs 
 such information only as would be required by the intelligent practitioner. The space thus 
 gained he has endeavored to till with a complete account of the physiological and therapeutic 
 properties of all ihe articles of the Materia Medica, their u-es in all the varieties of di^ease, 
 their pharmacopoeial preparations, and the mode in which they may be most succes?fully em- 
 ployed. The subject of General Therapeutics will be fognd more fully developed than is cus- 
 tomary in works of this nature; but while general principles will be careluUy enunciated and 
 developed, mere theoretical speculations will be avoided. The labor of many years devoted to 
 the work has enabled the author to accumulate and record the results of the experience of the 
 highest authorities in all countries, and his watchful care in incorporating the latest observations 
 and researches is a guarantee that the whole will be found fully brought up to the day, with all 
 that may be regarded as worthy of confidence. 
 
 The work is therefore presented as a practical companion for the active physician who may 
 desire to keep himself on a level with the advance of his profession, as well as a text-book for 
 the student entering upon his medical education. The long delay which has occurred in its 
 appearance ha> been caused by the determination of the author to spare no pains in rendering 
 it complete on every point : it is now, however, proceeding rapidly through the press, and the 
 publisliers expect to have it in readiness lor the fall sei^sions of the medical schools. 
 
 A COMPLETE ENCYCLOPEDIA OP MATERIA MEDICA. 
 
 THE 
 
 ELEMENTS OF MATERIA MEDICA AM THERAPEUTICS. 
 
 BY JONATHAN PEREIRA, M. D., F. R. S., &c. 
 2[f)trTi gimerfcan HDitioit, lenlavfletr anU fimprobeTi Ijb Hje Slutljor. 
 
 INCLUDING 
 
 NOTICES OF MOST OF THE MEDICINAL SUBSTANCES IN USE IN THE CIVILIZED WORLD, 
 
 AND FORMING AN 
 
 ENCYCLOPEDIA OF MATERIA MEDICA. 
 
 Edited by JOSEPH CARSON, M. D., 
 Professor of Materia Medica and Pharmacy in the University of Pennsylvania, &c. 
 
 hi two very large octavo volumes q/"2100 pages, hi small type, with over 450 illustrations, 
 strongly hound in leather, with raised hands, price §9. 
 
 The Second Volume will no longer be sold separate. 
 
 MEDICAL BOTANY; 
 
 OR, 
 
 DESCRIPTIONS OF THE MORE IMPORTANT PLANTS USED IN MEDICINE, 
 With their History, Properties, and Modes of Administration. 
 
 By R. EGLESFELD GRIFFITH, M. D., 
 
 Author of "A Universal Formulary," &c. 
 
 WITH UPWARDS OF THREE HUNDRED ILLUSTRATIONS. 
 
 In one large and very handsome octavo volume of 100 pages ; extra cloth, price $3. 
 
30 
 
 BLANCHARD AND LEA'S 
 
 MATERIA MEDICA AND THERAPEUTICS. 
 
 INCLUDING THE PREPARATIONS OF 
 
 THE PHARMACOPCEIAS OF LONDON, EDINBURGH, DUBLIN, 
 AND OF THE UNITED STATES. 
 
 WITH MANY NEW MEDICINES. 
 
 By J. FORBES BOYLE, M.D.,F.R.S., &c. 
 
 Edited BY JOSEPH CARSON, M.D., 
 
 Professor of Materia Medica and Pharmacy in the University of Pennsylvania, &c. 
 
 In one 
 
 very handsome octavo volume 
 
 of nearly 
 
 seven hundred pages, 
 
 with about one hundred 
 
 beautiful illustrations on wood. 
 
 Extra cloth, price $3. 
 
 Senna and its Adulterations. 
 
 This work is, indeed, a most valuable one, and will 
 fill up an important vacancy that existed between Dr. 
 Pereira's most learned and complete system of Mate- 
 
 ria Medica, and the class of productions on the other 
 extreme, which are necessarily imperfect from their 
 small extent. — British and Foreign Medical Review. 
 
 Ne-vr and Revised Edition. 
 
 SYNOPSIS OF THE COURSE OF LECTURES ON MATERIA MEDICA AND PHAR- 
 MACY, delivered in the University of Pennsylvania. By Joseph Carson, M. D., Professor 
 of Materia Medica and Pharmacy in the University of Pennsylvania. Second edition, revised. 
 In one very neat octavo volume, of 208 pages, cloth, f 1 50. 
 
 THE THREE KINDS OF COD-LIVER OIL, comparatively considered, with their Chemical 
 and Therapeutic properties. By D. L. De Jongh, M. D. 12mo., extra cloth, 75 cents. 
 
 CABPENTER ON THE USE OF ALCOHOLIC LIQUORS IN HEALTH 
 
 AND DISEASE. 'New edition, with a Preface by D. F. Condie, M. D. In one neat 12mo. 
 volume, extra cloth, pp 178. {Just Issued.) 50 cents. 
 
 THE MEDICAL FORMULARY; being a collection of Prescriptions, derived 
 from the Writings and Practice of many of the most eminent Physicians of America and 
 Europe : together with the usual Dietetic Preparations and Antidotes for Poisons. To which 
 is added an Appendix, on the Endermic Use of Medicines, and on the uses of Ether and Chlo- 
 roform. The whole accompanied with a few brief Pharmaceutic and Medical observations. 
 By Benjamin Ellis, M. D. Tenth edition, revised and much extended, by Robert P. Tho- 
 mas. M. D., Professor of Materia Medica in the Philadelphia College of Pharmacy, &c. In 
 one neat octavo volume, extra cloth, of three hundred pages, price $1 75. 
 
 After an examination of the new matter and the 
 alterations, we believe the reputation of the work 
 built up by the author, and the late distinguished 
 editor, will continue to flourish under the auspices of 
 the present editor, who has the industry and accuracy, 
 and, we would say, conscientiousness requisite for the 
 responsible task, — Ameriwn Journal of Pharmacy. 
 
 It will prove particularly useful to students and 
 young practitioners, ss the most important pre.scrip- 
 tions employed in modern practice, which lie scattered 
 through our medical literature, are here collected and 
 conveniently arranged for reference. — Charleston Med. 
 Journal and Review. 
 
MEDICAL AND SCIENTIFIC PUBLICATIONS. 
 
 31 
 
 New and Enlarged Edition — (Just Issued.) 
 
 IST E W^ R EM E D I E S : 
 
 WITH FORMUIJ] FOR THEIR PREPARATION AND ADMINISTRATION. 
 BY ROBLEY DUNOLISON, M. D., 
 
 Professor of the InslitiUes of Medicine, &c. ia the Jefferson Medical College, Philadelphia. 
 
 Seventh Edition, with extensive Additions. 
 
 In one very targe octavo volume of IIQ pages, leather, $3 75. 
 
 As the value of a work sucih as the present is greatly enhanced by the thoroughness with 
 which all the latest improvements and discoveries are embodied in its pages, the author has 
 spared no pains in preparing the present edition to render it a complete exposition of the most 
 recent aspect of therapeutic science. A large number of additional articles have been introduced, 
 and many of the older ones have been rewritten to adapt them to the present condition of the 
 subject. A very considerable increase in the size of the page has accommodated these additions 
 without unduly swelling the bulk of the volume, and it is confidently presented as in every 
 respect worthy a continuance of the very great favor which it has thus far received. 
 
 This new and much enlarged edition of Dr. Dungli- 
 pon's very valuable work will be welcomed by the pro- 
 fession already well acquainted with its merits. The 
 Tast research and thorough information which the 
 author has brought to the execution of his labors, aie 
 evident upon every page; and he is entitled to the 
 hearty thanks of his brethren for this and the many 
 other good things which he has done. Few would 
 willingly be without this excellent volume who desire 
 not only to know " new remedies" thoroughly, but 
 also to test their efficacy. — Boston Med. and Surg. 
 Journal, Aug. 1856. 
 
 It may be considered almost a work of supereroga- 
 tion to enter Into an elaborate criticism of a work 
 ■which has reached its se.re.nth edition. The public has 
 pronounced in the most authoritative manner its ver- 
 dict, and we are cerlainly not disposed in the present 
 instance to dispute its decision. In truth, such books 
 a.« this will always be favorably received by the pro- 
 fession of our country. They are labor-saving pro- 
 ductions, which, at the expense of much research and 
 
 reading to the author, condense in a convenient space 
 the novelties and discoveries of the age. The present 
 edition of this work is considerably enlarged and im- 
 proved. The author, with his accustomed accuracy, 
 has elaborated and ampliiied many of the articles but 
 casually or imperfectly treated of in the former edi- 
 tions ; and he has also added considerably to the list 
 of new remedies. Abiut thirty new agents or novel 
 applications of old remedies are introduced to the 
 notice of the readerln this edition. — Va. Med. o.nd Surg. 
 Journal, Sept. 1S56. 
 
 As a work of reference upon all new remedies, this 
 is one of the most complete with which we are ac- 
 quainted. The quotations of authorities are extensive, 
 minute, and carefully given; and we are satisfied that 
 no medical man would regret following our advice to 
 acquire it, as daily opportunities will occur in which 
 he may both test its value and increase his own know- 
 ledge, in searching for the practical information it 
 affords. — British and Foreign Med.-Chirurgical Review, 
 July, 1857. 
 
 A. n3ISI^ENS.A.TOIl Y; 
 
 Commentary on the Plmrmacopceias of Great 
 Britain and the United States : 
 
 COMPRISING THE 
 
 Natural History, Description, Chemistry, Phar- 
 macy, Action, Uses, and Doses of the 
 Articles of the Materia Medica. 
 
 BY 
 
 R.V.CHRISTISON.M.D.,V.P.R.S.E.,&c. 
 
 SECOND EDITION, REVISED AND IMPROVED. 
 
 WITH A SUPPLEMENT 
 
 Containing the most important New Remedies, 
 
 WITH COPIOUS ADDITIONS 
 
 BY R. EGLESFELD GRIFFITH, M.D. 
 
 In one very latge and handsome octavo volume of over 
 
 1000 pages, with 213 engravings on wood; 
 
 leather, price $3 50. 
 
 It is not needful that we should compare it with the 
 other pharmacopoeias extant, which enjoj' and merit 
 the confidence of the profession : it is enough to say 
 that it appears to us as perfect as a Dispensatory, in 
 the present state of pharmaceutical science, could he 
 made. If it omits any details pertaining to this branch 
 of knowledge which the student has a right to expect 
 in such a work, we confess the omission has escaped 
 our scrutiny. We cordially recommend this work to 
 such of our readers as are in need of a Dispensatory. 
 They cannot make choice of a better. — Western Jour- 
 nal of Medicine and Surgery. 
 
 There is not in any language a more complete and 
 perfect Treatise. — iVew Ycrrk Annalist. 
 
 Aronitum napeltux. 
 
32 
 
 BLANCHARD AND LEA'S 
 
 THE GREAT LIBRARY OF PATHOLOGY— (Just Issued.) 
 
 Complete in 
 
 four handsome octavo volumes 
 
 bound in two, 
 
 containing about 
 
 twelve hundred and fifty large pages; 
 
 extra cloth, 
 
 price $5 50. 
 
 Medullary Carcinu?na. 
 
 A MANUAL OF PATHOLOGICAL ANATOMY. 
 
 BY CARL ROKITANSKY, M. D., 
 
 Curator of the Imperial Pathological Museum and Professor at ihe University of Vienna. 
 
 Vol. I —Manual of General Pathological Anatomy. Translated by W. E. Swaine. 
 
 Vol. II.— Pathological Anatomy of the Abdominal Viscera. Translated by Edward Sieveking, 
 
 M.D. 
 Vol. III.— Pathological Anatomy of the Bones, Cartilages, Muscles, and Skin, Cellular and 
 
 Fibrous Tissues, Serous and Mucous Membrane, and Nervous System. Translated by C. 
 
 H. MooRE. 
 Vol. IV. — Pathological Anatomy of the Organs of Respiration and Circulation. Translated by 
 
 G. E. Day, M. D. 
 To render this large and important work more easy of reference, and at the same time less cum- 
 brous and costly, the four volumes have been arranged in two, retaining, however, the sepa- 
 rate paging, &c. 
 
 The publishers feel much pleasure in presenting to the profession of the United Slates the 
 great work of Prof. Rokitansky, which is universally referred to as the standard of authority by 
 the pathologists of all nations. Under the auspices of the Sydenham Society of London,' the 
 combined labor of four translators has at length overcome the almost insuperable difficulties 
 which have so long prevented the appearance of the work in an English dress, while the addi- 
 tions made from various papers and essays of the author present his views on all the topics em- 
 braced, in their latest published form. To a work so widely known, eulogy is unnecessary, and 
 the publishers would merely state that it is said to contain the results of not less than thirty 
 THOVSAND post-morte7n. examinations made by the author, diligently compared, generalized, and 
 wrought into one complete and harmonious system. 
 
 The profession is too well acquainted with the re- 
 putation of Roliitansky's work to need our assurance 
 that this is one of the most profound, thorough, and 
 valuable hooks ever issued from the medical press. 
 It is SMI fifeneris, and has no standard of comparison. 
 It is only necessary to announce that it is issued in a 
 form as cheap as is compatible with its size and pre- 
 servation, and its sale follows as a matter of course. 
 No library can be called complete without it. — Bvffalo 
 Med. Journal. 
 
 An attempt to give our readers any adequate idea 
 of the vast amount of instruction accumulated in 
 these volumes, would be feeble and hopeless. The 
 effort of the distinguished author to concentrate into 
 a small space his great fund of knowledge, has so 
 charged his text with valuable truths, that any at- 
 tempt of a reviewer to epitomize is at once paralyzed, 
 and must end in a failure. — Western Lancet. 
 
 As a hook of reference, therefore, this work must 
 prove of inestimable value, and we cannot too highly 
 recommend it to the profession. — Charleston Med. 
 Journal and Review. 
 
 This book is a necessity to every practitioner. — Am. 
 Med. Monthly, 
 
 The attempt to give our readers any adequate idea 
 of the vast storehouse of knowledge contained in these 
 volumes we feel to be utterlj' hopeless. The patient 
 labors of nearly thirty years in a field so vast as almost 
 to pass beyond our comprehension ; the accurate dis- 
 sections made on more than thirty thousand human 
 bodies are here carefully noted ; and the whole power 
 of a vigorous and practical mind has been concentrated 
 upon its execution. To the student of disease in its 
 very formation, and in its endless variety of develop- 
 ment; to the investigators of the true causes of symp- 
 toms, and the many phenomena displayed at the bed- 
 side; to all who strive to build up a sound and dis- 
 creet method of treatment, based, as it must always 
 be, on an accurate acquaintance with the pathological 
 conditions of each case: we recommend this noble 
 work as containing in itself everything which is 
 needed to the fullest comprehension of the subject. — 
 Va. Med. and Surg. Journal. 
 
 It is, everywhere, in fact, acknowledged to be fore- 
 most and unrivalled in its department. Only the most 
 earnest professional ardor, the most persevering labor, 
 could have enabled its author to amass the immense 
 amount of information contained in its pages. — Medi- 
 cal Examiner. 
 
MEDICAL AND SCIENTIFIC PUBLICATIONS. 
 
 33 
 
 New and thoroughly Revised Edition — (Just Issued.) 
 
 ELEMENTS OF PATHOLOGICAL ANATOMY. 
 
 BY SAMUEL D. GROSS, M. D., 
 
 Professor of Surgery in the Jefferson Medical College, Philadelphia. 
 
 Third Edition, Modified and thoroughly Revised, 
 
 ILLUSTRATED BY THREE HUNDRED AND FORTY-TWO ENGRAVINGS ON WOOD. 
 
 In one 
 
 large and very handsome 
 
 octavo volume, 
 
 of nearly 800 pages. 
 
 Price, 
 in extra cloth, $4 75; 
 
 leather, 
 raised bands, $5 25. 
 
 Keloid growth of the Face. 
 
 The very rapid advances in the Science of Pathological Anatomy during the last few years 
 have rendered essential a thorough modification of this work, with a view of making it a correct 
 exponent of the present state of the subject. The very careful manner in which this task has 
 been executed, and the amount of alteration which it has undergone, have enabled the author 
 to say that "with the many changes and improvements now introduced, the work majr be re- 
 garded almost as a new treatise," while the efforts of the author have been seconded as regards 
 the mechanical execution of the volume, rendering it one of the handsomest productions of the 
 American press. A very large number of new and beautiful original illustrations have been 
 introduced, and the work, it is hoped, will fully maintain the reputation hitherto enjoyed by it 
 of a complete and practical exposition of its difficult and important subject. 
 
 We most sincerely congratulate the author on the 
 successful manner in which he has accomplished his 
 proposed object. His book is most admirably calcu- 
 lated to fill up a blank which has long been felt to 
 exist in this department of medical literature, and as 
 such must become very widely circulated amongst all 
 classes of the profession. — Dublin Quarterly Journ. of 
 Med. Science, Nov. 1857. 
 
 We have been favorably impressed with the general 
 manner in which Dr. Gross has executed his task of 
 affording a comprehensive digest of the present state 
 of the literature of Pathological Anatomy, and have 
 much pleasure in recommending his work to our read- 
 ers, as we believe one well deserving of diligent pe- 
 rusal and careful study. — Montreal Med. Chron., Sept. 
 1857. 
 
 ATLAS OF PATHOLOGICAL HISTOLOGY. 
 
 BY GOTTLEIB GLtJGB, M. D., 
 
 Professor of Physiology and Pathological Anatomy in the University of Brussels, &c. 
 TRANSLATED, WITH NOTES AND ADDITIONS, 
 
 BY JOSEPH LEIDY, M. D., 
 
 Professor of Anatomy in the University of Pennsylvania, &c. 
 
 In one handsoine volume, large imperial quarto, with 320 Figures, plain and colored, 
 on twelve copperplate engravings, price $5 00. 
 
 This being, as far as we know, the only work in 
 which pathological histology is separately treated of 
 in a comprehensive manner, it will, we think, for this 
 reason, be of infinite service to those who desire to 
 investigate the subject systematically, and who have 
 felt the difficulty of arranging in their minds the un- 
 
 3 
 
 connected observations of a great number of authors. 
 The development of the morbid tissues, and the format 
 tion of abnormal products, may now be followed and 
 studied with the same ease and satisfaction as the best 
 arranged system of Physiology. — American Medical 
 Journal. 
 
34 
 
 BLANCHARD AND LEA'S 
 
 PATHOLOGICAL MANUAL- (Lately Published.) 
 
 Pyelitis. 
 
 Fibrinous Deposits in Granular Kidney. 
 
 A MANUAL OF PATHOLOGICAL ANATOMY. 
 
 BY C. HANDFIELD JONES, M. D., F. E. S., 
 
 Lecturer on Physiology at St. Mary's Hospital, &c. 
 
 AND 
 
 EDWARD H. SIEVEKING, M. D., 
 
 Lecturer on Materia Medica at St. Mary's Hospital. 
 
 FIRST AMERICAN EDITION, REVISED. 
 
 With three hundred and ninety-seven Engravings on "Wood. 
 
 Li one large and very handsome octavo volume of seven hundred and thirty-four pages, 
 
 leather, $3 75. 
 
 As a concise text-book, containing, in a condensed form, a complete 
 outline of what is known in the domain of Pathological Anatomy, it 
 is perhaps the hest work in the English language. Its great merit 
 consists in its completeness and brevity, and in this respect it supplies 
 a great desideratum in our literature. Heretofore the student of 
 pathology was obliged to glean from a great number of monographs, 
 and the field was so extensive that but few cultivated it with any de- 
 gree of success. The authors of the present work have sought to 
 correct this defect by placing before the reader a summary of ascer- 
 tained facts, together with the opinions of the most eminent patho- 
 logists both of the Old and New World. As a simple work of reference, 
 therefore, it is of great value to the student of pathological anatomy, 
 and should be in every physician's library. — Western Lancet. 
 
 AYe urge upon our readers and the profession generally the import- 
 ance of informing themselves in regard to modern views of pathology, 
 and recommend to them to procure the work before us as the best 
 means of obtaining this information. — Stethoscope. 
 
 In offering the above titled work to the public, the authors have 
 not attempted to intrude new views on their professional brethren, 
 but simply to lay before them, what has long been wanted, an outline 
 of the present condition of pathological anatomy. In this they have 
 been completely successful. The work is one of the best compila- 
 tions which we have ever perused. The opinions and discoveries of 
 all the leading pathologists and physiologists are engrossed, so that 
 by reading any subject treated in the book you have a .synopsis of the 
 views of the most approved authors. — Charleston Medical Journal 
 and Review. 
 
 We have no hesitation in recommending it as worthy of careful 
 and thorough study by every member of the profession, old or young. 
 — N. W Med. and Surg. Journal. 
 
 to be largely useful, as it suits itself to those busy m en 
 who have little time for minute investigation, and 
 prefer a summary to an elaborate treatise. — Buffalo 
 Medical Journal. 
 
 Osteophytes in lower end of Femur. 
 
 From the casual examination we have given we are 
 inclined to regard it as a text-book, plain, rational, and 
 intelligible, such a book as the practical man needs 
 for daily reference. For this reason it will be likely 
 
 GENERAL PATHOLOGY; 
 
 As Conducive to the Establishment of Rational Principles for the Prevention and Cure of Dis- 
 ease. A Course of Lectures delivered at St. Thomas's Hospital. By John Simon, F. R. S 
 &c. In one neat octavo volume, extra cloth, $1 25. 
 
MEDICAL AND SCIENTIFIC PUBLICATIONS. 
 
 35 
 
 BARCLAY ON DIAGNOSIS— A New Work, Now Ready (1858). 
 
 A MANUAL OF MEDICAL DIAGNOSIS; 
 
 be™ an analysis of the signs and symptoms of disease. 
 
 By a. W. BARCLAY, M. D., 
 
 Assistant Physician to St. George's Hospital, &o. 
 Ill one neat octavo volume of 424 pages ; extra cloth, price f 2. 
 
 Of works exclusively devoted to this important 
 branch, our profession has at command, comparative- 
 ly, hut few, and therefore, in the publication of the 
 present work, Messrs. Blanchard & Lea have conferred 
 a great favor upon us. Dr. Barclay, from having occu- 
 pied, for a long period, the position of Medical Regis- 
 trar at St. George's Hospital, possessed advantages for 
 correct observation and reliable conclusions, as to the 
 significance of symptoms, which have fallen to the lot 
 of but few, either in his own or any other country. 
 He has carefully systematized the results of his ob- 
 servation of over twelve thousand patients, and by his 
 diligence and judicious classification, the profession 
 has been presented with the most convenient and re- 
 liable work on the subject of Diagnosis that it has 
 been our good fortune ever to examine; we can, there- 
 fore, say of Dr. Barclay's work, that from his system- 
 atic manner of arrangement, his work is one of the 
 best works " for reference" in the daily emergencies 
 of the practitioner, with which we are acquainted; 
 but, at the same time, we would recommend our read- 
 ers, especially the younger ones, to read thoroughly 
 and study diligently the whole work, and the '•' emer- 
 gencies" will not occur so often. — Southern Med. and 
 Surg. Journal, March, 1S58. 
 
 To give this information, to supply this admitted 
 deficiency, is the object of Dr. Barclay's Manual. The 
 task of composing such a work is neither an easy nor 
 a light one: but Dr. Barclay has performed it in a 
 manner which meets our most unqualified approba- 
 tion. He is no mere theorist; he knows his work tho- 
 roughly, and in attempting to perform it, has not ex- 
 ceeded his powers. — British Med. Journal, Dec. 5, 1867. 
 
 We venture to predict that the work will be deserv- 
 edly popular, and soon become, like Watson's Practice, 
 an indispensable necessity to the practitioner. — iV". O. 
 Med. Journal, April, 1858. 
 
 An inestimable work of reference for the young 
 practitioner and student. — Nashville Medical Journal, 
 May, 1858. 
 
 We hope the volume will have an extensive circula- 
 tion, not among students of medicine only, but prac- 
 titioners also. They will never regret a faithful study 
 of its pages. — Cincinnati Lancet, March, 1858. 
 
 This Manual of Medical Diagnosis is one of the most 
 scientific, useful, and instructive works of its kind that 
 we have ever read, and Dr. Barclay has done good ser- 
 vice to medical science in collecting, arranging, and 
 analyzing the signs and symptoms of so many dis- 
 eases.— iV. J. Med. and Surg. Reporter, March, 1858. 
 
 We hail the appearance of this valuable book, com- 
 ing to us in its present exceedingly neat style, as an 
 important acquisition to medical literattire. It is a 
 work of high merit, both from the vast importance of 
 the subject upon which it treats, and also from the 
 real ability displayed in its elaboration. In conclu- 
 sion, let us bespeak for this volume that attention of 
 every student of our art which it so richly deserves — 
 that place in every medical library which it can so 
 well adorn. — T!ie Peninsular and Independent Medical 
 Journal, Sept. 1858. 
 
 Restricted as we are to certain limits, we can hardly 
 do more than give this brief synopsis, which will serve, 
 however, to convey to the reader an idea of the scope 
 and the number and variety of diagnostic details of 
 Dr. Barclay's volume. It was much wanted, and is 
 full of instruction on a branch of pathology which 
 furnishes we will not say the only, but certainly the 
 chief and the safest, indications for the treatment of 
 disease. — N. A. Medico-Chir. Review, May, 1858. 
 
 We conclude by assuring the honest and earnest 
 student who has acquainted himself sufficiently with 
 the principles of physiology and the details of anato- 
 my, that he could not better aid or advance his clinical 
 investigations, than by carrying this work with him 
 to the bedside of his patients, and the junior practi- 
 tioner will find much in its small compass to repay a 
 careful and perhaps repeated perusal. — Charleston, 
 Med. Journal and Review, May, 1858. 
 
 The author writes with a confidence which severe 
 and careful study can alone justify. There is a full 
 table of contents, and a most copious index, which in 
 such a work is invaluable. In conclusion, we can ho- 
 nestly recommend this work to the profession — to the 
 junior members of it as a handbook of study; to the 
 seniors, as a useful compendium of things to be re- 
 membered in cases of obscurity. — Medical Times and 
 Gazette, London, Nov. 14, 1857. 
 
 CYCLOP J]DIA OF PRACTICAL MEDICIM; 
 
 COMPRISING 
 
 Treatises on the Nature and Treatment of Diseases, Materia ledica and Therapeutics, 
 Diseases of Women and Children, Medical Jurisprudence, &c. &c. 
 
 EDITED BY 
 
 JOHN FORBES, M.D., F. R. S., ALEXANDER TWEEDIE, M. D., F. R. S., 
 
 AND JOHN CONNOLLY, M. D. 
 
 Revised, with Additions, 
 
 BY ROBLEY DUNGLISON, M. D. 
 
 COMPLETE, IN FOUR LARGE SUPER-ROYAL OCTAVO VOLUMES. 
 
 Containing thirty-two hundred and fifty-four unusually large pages, in doiible cokimiis, 
 printed on good paper, vnth a new and clear type. 
 
 • THE WHOLE WELL AND STRONGLY BOUND IN LEATHER, WITH RAISED BANDS AND DOUBLE TITLES. Price $12 00. 
 
 This work contains no less than TOUR HUNDRED AND EIGHTEEN DISTINCT TREATISES, 
 
 By Sixty-eight Distinguished Physicians. 
 
 The most complete work on Practical Medicine ex- 
 tant ; or, at least, in our language. — Buffalo Medical 
 and Surgical Journal. 
 
 For reference, it is above all price to every practi- 
 tioner. — Western Lancet. 
 
36 
 
 BLANCHARD AND LEA'S 
 
 New and Much Improved Edition. 
 
 PRINCIPLES OF MEDICINE. 
 
 AN ELEMENTARY VIEW OF THE CAUSES, NATURE, TREATMENT, 
 DIAGNOSIS AND PROGNOSIS OF DISEASE, 
 
 WITH BRIEF REMARKS ON HYGIENICS, OR THE PRESERVATION OF HEALTH. 
 
 BY CHARLES J. B. WILLIAMS, M.D.,F.R.S. 
 
 A new American, from the Third and Revised Liondon Edition. 
 
 In 0716 neat octavo volume, of about five hundred large pages, leather, $2 50. 
 
 The very recent and thorough revision which this work has enjoyed at the hands of (he au- 
 thor has: brought it so completely up to the present stale of the subject that in reproducing it no 
 additions have been found neces^sary. The success which the work has heretofore met shows 
 that its importance has been appreciated, and in its present form it will be found eminentl}' wor- 
 thy a continuance of the same favor, possessing as it does the strongest claims to the attention 
 of the medical student and practitioner, from the admirable manner in which the various inqui- 
 ries in the different branches of pathology are investigated, combined, and generalized by an 
 experienced practical physician, and directly applied to the investigation and treatment of disease. 
 
 We find that the deeply-interesting matter and style 
 of this book have so far fascinated us, that we have 
 unconsciously hung upon its pages, not too long, in- 
 deed, for our own profit, but longer than reviewers 
 can be permitted to indulge. We leave the further 
 analysis to the student and practitioner. Our judg- 
 ment of the work has already been sufficiently ex- 
 pressed. Itis a judgment of almost unqualified praise. 
 The work is not of a controversial, but of a didactic 
 character ; and, as such, we hail it, and recommend 
 it for a text-book, guide, and constant companion to 
 every practitioner and every student who wishes to 
 extricate himself from the well-worn ruts of empiri- 
 cism, and to base his practice of medicine upon prin- 
 ciples — London Lancet, Dec. 27, 1856. 
 
 A text-book to which no other in oxxT language is 
 comparable. — Charleston Me.dical Journal. 
 
 No work has ever achieved or maintained a more 
 deserved reputation. — Virginia Med. and Surg. Journ. 
 
 The Principles of Medicine of Dr. Williams has, by 
 common consent, become one of the classics of our 
 profession. Few works have done more towards ac- 
 complishing that union of the science and practice of 
 medicine so indispensable for its perfection, and which 
 are too apt,to be found separate from each other — a 
 separation, the inevitable tendency of which must ever 
 be to favor empiricism. The rapid sale of three edi- 
 tions of this work in our country we regard as a 
 marked tribute to its value, and as no less compli- 
 mentary to the discrimination and appreciation of the 
 profession here in giving rise to such a demand. — jV. 
 Y. Medical Times. 
 
 The work as now presented to the public, is perhaps 
 the most perfect of any other treating on similar sub- 
 jects; it combines the science and the art, the theory 
 
 and the practice, in a most masterly manner, and we 
 feel confident that as knowledge of the practical views 
 and scientific principles laid down in the book become 
 generally known, medicine — practical medicine— will 
 advance, in the same proportion, to a greater perfec- 
 tion and certainty. — N. Orleans Med. and Su7-g. Journ. 
 
 There is no work in medical literature which can fill 
 the place of this one. It is the Primer of the young 
 practitioner, the Koran of the scientific one. Three 
 large editions of it have already been exhausted in the 
 United States, and now the fourth is presented. It 
 must have, so long as the size of the volume remains 
 uncumbersome, the first place among pathological au- 
 thorities. We feel warranted in saying that no medi- 
 cal book has yet been written which contains so much 
 in the small number of pages which compose this one, 
 and yet it is complete. It takes up disease at its very 
 foundation, and treats of its fundamental nature in a 
 logical and inductive style. — The Stethoscope. 
 
 This exceedingly valuable work is the best, we be- 
 lieve, in the whole round of medical literature. The 
 division of the different subjects is excellent. The au- 
 thor's method of investigation and mode of expression, 
 in our judgment, are faultless. We can most cheer- 
 fully commend the work as the best that has ever 
 appeared on the principles of medicine, and we would 
 advise young practitioners especially to furnish them- 
 selves with a copy, as well for the value of the informa- 
 tion it contains as for the facilities it will afford them 
 in the prosecutionof their own investigations. — Soutli- 
 ern Journal of the Med. and Phys Sciences. 
 
 The best exposition in our language, or, we believe, 
 in any language, of rational medicine, in its present 
 improved and rapidly improving state. — British and 
 Foreign Medico-Chirurgical Review. 
 
 WHAT TO OBSERVE 
 
 AT THE BEDSIDE AND AFTER DEATH, IN MEDICAL CASES. Published under the 
 authority of the London Society for Medical Observation. A new American from the Se- 
 cond and Revised London edition. In one very handsome volume, royal 12mo , extra cloth, 
 
 A MANUAL OF CLINICAL MEDICINE AND PHYSICAL DIAGNOSIS. By 
 Thomas H. Tanner, M. D., Physician to the Hospital for Women, &c. Second American 
 edition. In one neat volume, small 12mo., extra cloth, 88 cts. ; or in flexible cloth for the 
 pocket, 80 cts. 
 
 DUNGLISON'S PRACTICE. 
 
 THE PRACTICE OF MEDICINE: A Treatise on Special Pathology and Thera- 
 peutics. By RoBLEY DuNGLisoN, M. D., Professor of the Institutes of Medicine in Jefferson 
 Medical College, Philadelphia. Third and revised edition. In two large octavo volumes of 
 about fifteen hundred pages; leather, f6 25. 
 
MEDICAL AND SCIENTIFIC PUBLICATIONS. 
 
 37 
 
 New and much enlarged edition of "WATSON'S PKACTICE"— Just Ready (185S). 
 
 LECTURES ON THE 
 
 PRKfCIPLES AND PRACTICE OF PHYSIC. 
 
 DELIVERED AT KING'S COLLEGE, LONDON. 
 BY THOMAS WATSON, M. D., 
 
 Late Physician to the Middlesex Hospital, &c. 
 
 ^ mbs ^nt^ritait, from t^e last llebiseb nnb inlargcb ^itgltsl^ ©iritioit. 
 With Additions, by D. FRANCIS CONDIE, M.D., 
 
 Author of "A Practical Treatise on the Diseases of Children," &c. 
 
 WITH ONE HUNDRED AND EIGHTY-FIVE ILLUSTRATIONS ON WOOD. 
 
 Bi one very large and handsome vohtme, imperial octavo^ of over 1200 large and closely printed 
 pages, in sm,all type; the whole strongly botind in leather, with raised bands. Price $4 25. 
 
 The publishers feel that they are rendering a service to 
 the American profession in presenting at so very mode- 
 rate a price this vast body of sound practical information. 
 Whether as a guide for the student entering on a course 
 of instruction, or as a book of reference for daily con- 
 sultation by the practitioner, "Watson's Practice" has 
 long been regarded as second to none; the soundness and 
 fulness of its teachings, the breadth and liberality of its 
 views, and the easy and flowing style in which it is writ- 
 ten having won for it the position of a general favorite. 
 That this high reputation might be fully maintained, the 
 author has subjected it to a thorough revision ; every 
 portion has been examined with the aid of the most re- 
 cent researches in pathology, and the results of modern 
 investigations in both theoretical and practical subjects 
 have been carefully weighed and embodied throughout its 
 pages. The watchful scrutiny of the editor has likewise 
 introduced whatever possesses immediate importance to 
 the American physician in relation to diseases incident to 
 our climate which are little known in England, as well as 
 those points in which experience here has led to different 
 modes of practice ; and he has also added largely to the 
 series of illustrations, believing that in this manner valu- 
 able assistance may be conveyed to the student in eluci- 
 dating the text. The work will, therefore, be found 
 thoroughly on a level with the most advanced state of 
 medical science on both sides of the Atlantic. 
 
 The additions which the work has received are shown 
 by the fact that notwithstanding an enlargement in the 
 size of the page, more than two hundred additional pages 
 have been necessary to accommodate the two large vo- 
 lumes of the London edition (which sells at ten dollars) 
 within the compass of a single volume, and in its present 
 form it contains the matter of at least three ordinary oc- 
 tavos. Believing it to be a work which should lie on the 
 table of every physician, and be in the hands ot every 
 student, the publishers have put it at a price within the 
 reach of all, making it one of the cheapest books as yet 
 presented to the American profession, while at the same 
 time the beauty of its mechanical execution renders it an 
 exceedingly attractive volume. 
 
 Stomach contracted from chronic 
 ulctraaon. 
 
38 
 
 BLANCHARD AND LEA'S 
 
 New and Improved Edition — Now Ready (June, 1859). 
 
 ELEMENTS OE MEDICINE: 
 A COMPENDIOUS VIEW OF PATHOLOGY AND THERAPEUTICS; 
 
 OR, THE HISTORY AND TREATMENT OF DISEASES. 
 BY SAMUEL H. DICKSON, M. D., 
 
 Professor of the Practice of Medicine in the Jefferson Medical College of Philadelphia. 
 In one large and handsome octavo volume of 750 pages ; leather, $3 75. 
 
 The steady demand which has so soon exhausted the first edition of this work, sufficiently 
 shows that the author was not mistaken in supposing that a volume of this character was need- 
 ed — an elementary manual of practice, which should present the leading principles of medicine 
 with the practical results, in a condensed and perspicuous manner. Disencumbered of unneces- 
 sary detail and fruitless speculations, it embodies what is most requisite for the student to learn, 
 and at the same time what the active practitioner wants when obliged, in the daily calls of his 
 profession, to refresh his memory on special points. The clear and attractive style of the au- 
 thor renders the whole easy of comprehension, while his long experience gives to his teachings 
 an authority everywhere acknowledged. Few physicians, indeed, have had wider opportunities 
 for observation and experience, and few, perhaps, have used them to better purpose. As the 
 result of a long life devoted to study and practice, the present edition, revised and brought up 
 to the date of publication, will doubtless maintain the reputation already acquired as a condensed 
 and convenient American text-book on the Practice of Medicine. 
 
 A few notices of the first edition are appended. 
 
 This book is eminently what it professes to be; a dis- 
 tinguished merit in these days. Desisned for " Teachers 
 and Students of Medicine," and admirably suited to 
 their wants, we think it will be received, on its own 
 merits, with a hearty welcome. — Boston Med. and Surg. 
 Journal. 
 
 The volume is admirably adapted to supply a want 
 long since felt by the American student and young 
 practitioner of medicine, with reference to whom it has 
 evidently been prepared. This class will find it a ju- 
 dicious and valuable compend of the elements of 
 medicine. — N. T. Journal of Medicine, Sept. 1856. 
 
 Indited by one of the most accomplished writers of 
 our country, as well as by one who has long held a 
 high position among teachers and practitioners of 
 medicine, this work is entitled to patronage and care- 
 ful study. The learned author has endeavored to con- 
 dense in this volume most of the practical matter con- 
 tained in his former productions, so as to adapt it to 
 the use of those who have not time to devote to more 
 extensive works. — Southern Med. and Surg. Journal. 
 
 We can strongly recommend Dr. Dickson's work to 
 our readers as one of interest and practical utility, 
 well deserving of a place in their libraries as a book 
 of reference; and we especially commend the first part 
 as presenting an admirable outline of the principles 
 of medicine. — Dublin Quarterly Journal. 
 
 This volume is designed as a text-book for teachers 
 and students; but its merits extend far beyond its 
 modest dedication; it is a complete treatise upon me- 
 
 dicine, and one that will stand the test of years. The 
 arrangement is simple, a feature oftentimes obscured 
 in otherwise excellent works. This Treatise is a valu- 
 able addition to our medical literature, and in the clear 
 and accurate descriptions, purity, and simplicity of 
 style, and soundness of precept, the reader will find 
 much to admire and adopt, and not a little that calls 
 for deep reflection. We cordially recommend this 
 volume to our readers, whether old practitioners or 
 students, for we take it that the physician should al- 
 ways be a student. — American Lancet. 
 
 Prof Dickson's work supplies, to a great extent, a 
 desideratum long felt in American medicine. — iV. O. 
 
 Med. and Surg. Journal. 
 
 Estimating this work according to the purpose for 
 which it is designed, we must think highly of its me- 
 rits, and we have no hesitation in predicting for it a 
 favorable reception by both students and teachers. 
 
 Not professing to be a complete and comprehensive 
 treatise, it will not be found full in detail, nor filled 
 with discussions of theories and opinions, but em- 
 bracing all that is essential in theory and practice, it 
 is admirably adapted to the wants of the American 
 student. Avoiding all that is uncertain, it presents 
 more clearly to the mind of the reader that which i.s 
 established and verified by experience. The varied 
 and extensive reading of the author is conspicuously 
 apparent, and all the recent improvements and dis- 
 coveries in therapeutics and pathology are chronicled 
 in its pages. — Charleston Med. Journal. 
 
 A New Text-Book on Practice— (Lately Issued.) 
 
 A MANUAL OE THE PRACTICE OE MEDICINE. 
 
 BY GEORGE H. BARLOW, M. D., 
 
 Physician to Guy's Hospital, London, &c. 
 
 With Additions by D. E. CONDIE, M.D., 
 
 Author of "A Practical Treatise on the Diseases of Children," &c. 
 I7i one handsome octavo volume of over six Mmdred pages; leather, $2 75. 
 
 We recommend Dr. Barlow's Manual in the warm- 
 est manner as a most valuable vade-mecum. We have 
 had frequent occasion to consult it, and have found it 
 clear, concise, practical, and sound. It is eminently 
 a practical work, containing all that is essential, and 
 avoiding useless theoretical discussion. The work 
 supplies what has been for some time wanting, a 
 manual of practice based upon modern discoveries in 
 pathology and rational views of treatment of disease 
 It is especiiilly intended for the use of students and 
 junior practitioners, but it will be found hardly less 
 
 useful to the experienced physician. The American 
 editor has added to the work three chapters— on 
 Cholera Infantum, Yellow Fever, and Cerebro-spinal 
 Meningitis. These additions, the two first of which 
 are indispensable to a work on practice destined for 
 the profession in this countr}', are executed with great 
 judgment and fidelity, by Dr. Condie, who has also 
 succeeded happily in imitating the conciseness and 
 clearness of style which are such agreeable character- 
 istics of the originial 'hook.— Boston Med. and Surg. 
 Journal. 
 
MEDICAL AND SCIENTIFIC PUBLICATIONS. 
 
 39 
 
 LA ROCHE ON YELLOW FEVER— (Just Issued. 
 
 YELLOW FEYER, 
 
 CONSIDERED IN 
 
 ITS HISTORICAL, PATHOLOGICAL, ETIOLOGICAL, AND THERAPEUTICAL RELATIONS: 
 
 INCLUDING 
 
 A Sketch, of the Disease as it has occurred in Philadelphia from 1699 to 1854. 
 
 With an Bzamination of the Connedions between it and the Fevers known under the same name 
 in other parts of Temperate as well as in Tropical Regions, 
 
 BY R. LA ROCHE, M. D. 
 
 In two large and handsome octavo volumes of nearly 1500 pages ; extra cloth, $7. 
 
 The publishers are happy in being able at length to present to ihe profession this great work, 
 which they are assured will be regarded as an honor to the medical literature of the country. 
 As the result of many years of personal observation and study, as embodying an intelligent re- 
 sume of all that has been written regarding the disease, and as exhausting the subject in all its 
 various aspects, these volumes must at once talce the position of the standard authority and work 
 of reference on the many important questions brought into consideration. 
 
 From Professor S. H. Diclcson, Ckarlestmi, S. C. 
 A monument of intelligent and well-applied re- 
 search, almost without example. It is, indeed, in it- 
 self, a large lilirary, and is destined to constitute the 
 special resort as a book of reference, on the subject of 
 which it treats, to all future time. 
 
 We have not time at present, engaged as we are, by 
 day and by night, in the work of combating this very 
 disease, now prevailing in our city, to do more than 
 give this cursory notice of what we consider as un- 
 doubtedly the most able and erudite medical publica- 
 tion our country has yet produced. But in view of 
 the startling fact, that this, the most malignant and 
 unmanageable disease of modern times, has for several 
 years been prevailing in our country to a greater ex- 
 tent than ever before; that it is no longer confined to 
 either large or small cities, but penetrates country 
 villages, plantations, and farm-houses; that it is treated 
 with scarcely better success now than thirty or forty 
 years ago ; that there is vast mischief done by ignorant 
 pretenders to knowledge in regard to the disease, and 
 in view of the probability that a majority of southern 
 physicians will be called upon to treat the disease, we 
 trust that this able and comprehensive treatise will 
 be very generally read in the south. — Memphis Med. 
 Recorder. 
 
 This is decidedly the great American medical work 
 of the day — a full, complete, and systematic treatise, 
 unequalled by any other upon the all-important sub- 
 ject of Yellow Fever. The laborious, indefatigable, 
 and learned author has devoted to it many years of 
 arduous research and careful study, and the result is 
 such as will reflect the highest honor upon the author 
 and our country. — Southern Med. and Surg. Journal. 
 
 The genius and scholarship of this great physician 
 could not have been better employed than in the erec- 
 tion of this towering monument to his own fame, and 
 to the glory of the medical literature of his own coun- 
 try. It is destined to remain the great authority upon 
 the subject of Yellow Fever. The student and phy- 
 sician will find in these volumes a risumi of the sum 
 total of the knowledge of the world upon the awful 
 scourge which they so elaborately discuss. The style 
 is so soft and so pure as to refresh and invigorate the 
 mind while absorbing the thoughts of the gifted author, 
 
 while the publishers have succeeded in bringing the 
 externals into a most felicitous harmony with the 
 inspiration that dwells within. Take it all in all, it 
 is a book we have often dreamed of, but dreamed not 
 that it would ever meet our waking eye as a tangible 
 reality. — Nashville Journal nf Medicine. 
 
 We deem it fortunate that the splendid work of Dr. 
 La Roche should have been issued from the press at 
 this particular time. The want of a reliable digest of 
 all that is known in relation to this frightful malady 
 has long been felt — a want very satisfactorily met in 
 the work before us. We deem it but faint praise to 
 say that Dr. La Roche has succeeded in presenting the 
 profession with an able and complete monograph, one 
 which will find its way into every well ordered library. 
 — Va. Stethoscope. 
 
 Although we have no doubt that controversial trea- 
 tises on the mode of origin and propagation of the fever 
 in question will, as heretofore, occasionally appear, 
 yet it must be some time before another systematic 
 work can arise in the face of so admirable and care- 
 fully executed a one as the present. It is a mine of 
 information, quite an encyclopedia of references, and 
 resume of knowledge relative to what has been re- 
 corded upon the subject. — Loivlon Lancet. 
 
 A miracle of industry and research, constitviting a 
 complete library of reference on the disease of which 
 it treats. — Dublin Quarterly Journal. 
 
 Dr. La Roche's work embodies all that is wanted. 
 It is a compendium of the whole vast literature of 
 Yellow Fever. Thanks to his labors, the medical 
 scholar who desires to be profoundly conversant with 
 all that pertains to the subject need not go beyond 
 these two portly volumes. As embodying whatever 
 is important in all that has been hitherto written on 
 the subject, it will be a work for reference not less 
 valuable in ages to come than now. Its merit, how- 
 ever, by no means consists solely in its completeness 
 as an encyclopa^dian work. The author presents the 
 conclusions to which he is led by a philosophical in- 
 vestigation of the facts and opinions gathered from 
 past and contemporaneous publications. Of the sound- 
 ness of the conclusions the reader can judge from the 
 data which are spread before him. — Buffalo Med. Jour- 
 nal, Sept. 1856. 
 
 By the same Author. 
 
 PNEUMONIA; its Supposed Connectiot], Pathological and Etiological, with 
 
 Autumnal Fevers, including an Inquiry into the Existence and Morbid Agency of Malaria. 
 In one handsome octavo volume, extra cloth, of 500 pages. $3. 
 
 A more simple, clear, and forcible exposition of the 
 groundless nature and dangerous tendency of certain 
 pathological and etiological heresies, has seldom been 
 presented to our notice. — N. Y. Journal of Medicine 
 and Collateral Science. 
 
 This work should be carefully studied by Southern 
 physicians, embodying as it does the reflections of an 
 original thinker and close observer on a subject pecu- 
 liarly their own. — Virginia Medical and Surgical Jour- 
 nal. 
 
40 
 
 BLANCHARD AND LEA'S 
 
 New and Improved Edition— Just Issued. 
 A. 9 
 
 IN ONE 
 
 VERY HANDSOME OCTAVO VOLUME, 
 
 OF 
 
 FIVE HUNDRED PAGES. 
 
 ■WITH 
 
 Four exquisite 
 
 COLOEED PLATES, 
 AITD 
 
 NUMEROUS WOOD-CUTS. 
 Extra cloth, S3 00. 
 
 Suction of small Portal Vein and Canal. 
 
 ON DISEASES OF THE LIVER. 
 
 BY GEORGE BCDD, M.D., F. E. S., 
 
 Professor of Medicine in King's College, London, &c. 
 
 Spirit g^merkEit, from t^£ Cljirb anb finlarg^b l^onbon 6btlion, 
 
 Has fairly established for itself a place among the 
 classical medical literature of England. — Brilish and 
 Foreign Medico-Chir. Review, July, 1857. 
 
 Dr. Budd's Treatise on Diseases of the Liver is now 
 a standard work in Medical literature, and during the 
 intervals which have elapsed between the successive 
 editions, the author has incorporated into the text the 
 most striking novelties which have characterized the 
 recent progress of hepatic physiology and pathology ; 
 80 that although the size of the book is not percepti- 
 
 bly changed, the history of liver diseases is made more 
 complete, and is kept upon a level with the progress 
 of modern science. It is the best work on diseases of 
 the liver in any language. — London Med. Times and 
 Gazette., June 27, 1857. 
 
 This work, now the standard book of reference on 
 the disea.ses of which it treats, has been carefully re- 
 vised, and many new illustrations of the views of the 
 learned author added in the present edition. — Dublin 
 Quarterly Journal, Aug. 1857. 
 
 By the same Author— (Just Issued.) 
 ON THE ORGANIC DISEASES AND FUNCTIONAL DISORDERS OF 
 
 THE STOIVI^CH. 
 
 In one neat octavo voluTne, of two hundred and fifty pages, extra cloth, $1 50. 
 
 LALLEMAND AND WILSON ON SPERMATORRHCBA— (Now Ready). 
 A PRACTICAL TREATISE ON THE CAUSES, SYMPTOMS, AND 
 
 TREATMENT OF SPERMATORRHCBA. By M. Lallemand. Translated and edited 
 by Henry J. McDougall Third American edition. To whicli is added— ON DISEASES 
 OF THE VESICUL.'E SEMINALES, and their associated organs. With special re- 
 ference to the Morbid Secretions of the Prostatic and Urethral Mucous Membrane. By Mae- 
 Ris WiLSONj M. D. Ill one neat octavo volume, of about 400 pp., extra cloth. $2. 
 
 FEVERS, THEIR DIAGNOSIS, PATHOLOGY, AND 
 TREATMENT. Prepared and edited, with large 
 Additions, from the Essays on Fever in Tweedie's 
 Library. By Meredith Clymer, M. D. In one octavo 
 volume, of six hundred pages, $1 50. 
 
 HUGHES' CLINICAL INTRODUCTION TO THE 
 PRACTICE OF AUSCULTATION AND OTHER 
 MODES OF PHYSICAL DIAGNOSIS, IN DIS- 
 EASES OF THE LUNGS AND HEART. Second 
 American, from the second London edition. 1 vol. 
 royal 12mo., extra cloth, pp. 304. $1. 
 
 COPLAND ON PALSY.— Of the Causes, Nature, and 
 Treatment of Palsy and Apoplexy. In one volume, 
 royal 12mo., 80 cents. 
 
 BLAKISTON'S PRACTICAL OBSERVATIONS ON 
 CERTAIN DISEASES OF THE CHEST, and on 
 the Principles of Auscultation. In one vol., cloth, 
 8vo., pp. 384. $1 25. 
 
 BUCKLER ON THE ETIOLOGY, PATHOLOGY, 
 AND TREATMENT OF FIBRO-BRONCHITIS AND 
 RHEUMATIC PNEU.MONIA. In one Svo. vol., ex- 
 tra cloth, pp. 150. $1 25. 
 
MEDICAL AND SCIENTIFIC PUBLICATIONS. 41 
 
 FLINT ON RESPIRATORY ORGANS— (Just Issued.) 
 
 PHYSICAL EXPLORATION AND DIAGNOSIS 
 
 OF DISEASES AEFECTING THE RESPIRATORY ORGANS. 
 
 BY AUSTIN FLINT, M. D., 
 
 Professor of Clinical Medicine and Pathologj' in the University of Buffalo, &c. 
 I7i one large and handsome octavo volume of six hundred and thirty-six pages ; extra cloth, $3. 
 
 Dr. Flint is one of the most industrious and ener- 
 p;etio men in the medical profession of this country. 
 His previous contributions to our medical literature 
 have won for him both American and European repu- 
 tation, and we assure our readers that the present 
 volume is full of valuable and interesting matter. 
 We unhesitatingly commend the book to all who wish 
 to become well acquainted with thoracic diseases and 
 the signs by which they may be distinguished. — N. W. 
 Med. and Surg. Journal, Nov. 1856. 
 
 We have selected these points in the physical ex- 
 ploration of the chest not only from their importance, 
 but to show the manner in which Dr. Flint handles 
 his subject. Our readers will, we doubt not, agree 
 with us in the opinion that he has done this carefully, 
 thoroughly, and judiciously. — Charleston Med, Jour- 
 nal, Nov. 1856. 
 
 We can only state our general impression of the 
 
 A work of original observation of the highest merit. 
 We recommend the treatise to every one who wishes 
 to become a correct auscultator. Based to a very large 
 extent upon cases numerically examined, it carries 
 the evidences of careful study and discrimination upon 
 every page. It does credit to the author, and. through 
 him, to the profession in this country. It is, what we 
 cannot call every book upon aiiscultation, a readable 
 book. — Am. Journal Med. Sciences. 
 
 A work, of which we cannot but admire the spirit 
 that has presided over its composition. There is an 
 evident accuracy aimed at throughout by means of 
 the carefully noted cases, and a searching after truth 
 which recommends the volume highly to the attention 
 of the profession. — Med. Examiner. 
 
 This is the most elaborate work devoted exclusively 
 to the physical exploration of diseases of the lungs, 
 
 high value of this work, and cordially recommend it i with which we are acquainted in the English lan- 
 to all. We regard it, in point both of arrangement \ guage. From the high standing of the author as a 
 
 and of the marked ability of its treatment of the sub- 
 jects, aS destined to take the first rank in works of this 
 class. So far as our information extends, it has at 
 present no equal. To the practitioner, as well as the 
 student, it will be invaluable in clearing up the diag- 
 nosis of doubtful cases, and in shedding light upon 
 difficult phenomena. — Buffalo Med. Journal. 
 
 clinical teacher, and his known devotion, during many 
 years, to the study of thoracic diseases, much was to 
 be expected from the announcement of his determin- 
 ation to embody in the form of a treatise, the results 
 of his study and experience. — Boston Med. and Surg. 
 Journal. 
 
 By the same Author— (In Press.^ 
 THE DIAGNOSIS, PATHOLOGY, AND TREATMENT OF 
 
 DISEASES OE THE HE^HT. 
 
 In one neat octavo volume, of nearly 500 pages. 
 
 This work is now so far advanced that the publishers can promise it with confidence for the 
 autumn of 1859. The reputation of the author, and the attention which he lias long paid to this 
 department of pracical medicine, are sufficient guarantee that the present volume will supply 
 the want which has long been felt of a complete and authoritative treatise on the subject. 
 
 Just Issued, 
 
 MEDICAL NOTES AND REFLECTIONS. 
 
 BY SIK HENRY HOLLAND, Bart., F. E. S., 
 
 Physician in Ordinary to the Queen, &c. 
 FRON/1 -THE THIRD AND ENt-ARGED ENQI-ISH EDITION. 
 
 1)1 one handsome octavo volume of about five hundred pages, extra doth, $3 GO. 
 Just Issued. 
 
 CLINICAL LECTURES ON CERTAIN DISEASES OF THE 
 
 URINARY ORGANS, AND ON DROPSIES, 
 
 BY ROBERT BENTLEY TODD, M. D., F. R. S., 
 
 Physician to King's College Hospital, &c. 
 In one handsome octavo volume, of 270 pages, extra cloth, $1 50. 
 
 By the same Author — (In Press.) 
 
 CLINIC AiTlECTURES 
 ON OEKTAIN ACUTE DISEASES. 
 
 In one neat octavo volume, extra cloth. 
 
42 
 
 BLANCHARD & LEA'S 
 
 Publishing in the "Medical News and Library," 1858 and 1859. 
 PATHOLOGICAL AND PRACTICAL OBSERVATIONS 
 
 OX DISEASES OF THE ALIMENTARY CAXAL, (ESOPHAGUS, STOMACH, 
 
 CECUM, AND INTESTINES. 
 
 By S. 0. HABERSHOX, M. D., 
 
 Assistant Physician to and Lecturer on Materia Medica and Tiieraiieutics at Guy's Hospital. 
 
 WITH HANDSOME ILLUSTRATIONS ON WOOD. 
 
 |^° B}^ reference to 
 the Terms of the "Ame- 
 rican Journal of the 
 Medical Sciences," 
 pp. 3 and 4, it will be 
 seen that advance-pay- 
 ing subscribers obtain 
 this valuable practical 
 work without charg'e. 
 
 He takes us well through all the diseases, structural 
 and functional (as they are called), of the alimentary 
 canal. He begins at the pharynx, and carefully and 
 honestly follows the tube through all its constrictions, 
 dilatations, divarications, and appendices. He tells us 
 what misfortunes happen at every part of it: he de- 
 scribes the particular seat of the disease at each con- 
 ventional division of the apparatus; their anatomical 
 characters (when they have any); their general patho- 
 logy: the symptoms they excite; the conditions of the 
 system with which they are coincident; the particular 
 general disorder with which they are associated : and 
 he also tells us what aids medicine offers man to help 
 him through these numerous dangers and difficulties; 
 and how those aids are to be wisely used to their ends. 
 The practitioner will find it a valuable work of refer- 
 ence. — London Med. Times and Gaz.. Nov. 7, 1857. 
 
 Dr. Habershon abstains, as a rule, from speculations, 
 and confines himself mainly to the record of facts re- 
 lating to symptoms, morbid chanses, and treatment. 
 His remarks are illustrated by the histories of one I 
 
 THE 
 PATHOLOGY AND TREATMENT 
 
 OF 
 
 PULMOMRT TUBERCULOSIS, 
 
 AND ON 
 
 THE LOCAL MEDICATION OF PHARYNGEAL AND 
 LARYNGEAL DISEASES FREQUENTLY MIS- 
 TAKEN FOR OR ASSOCIATED 
 WITH PHTHISIS. 
 
 Chronic Ulcer of Stomach. 
 
 hundred and sixty-three cases, recorded in the ease- 
 books of Guy's Hospital, descriptive of the numerous 
 forms of disea.«e of the alimentary canal. The book 
 is therefore essentially practical; and on this ground, 
 and bearing evidence of being the work of a careful 
 observer, it forms an addition of value to the already 
 existing literature of Diseases of the Alimentary Canal. 
 British Med. Journal, Nov. 21, 1857. 
 
 Amongst the valuable treatises we have pointed out 
 there yet existed room for a work which should deal 
 but little with theory and scientific analyses, but con- 
 fine itself to the record of direct bedside and post- 
 mortem, room results. Dr. Habershon"s treatise sup- 
 plies this deficiency. We recommend Dr. Habershon's 
 treatise as a valuable repertory of clinical experience, 
 of very trustworthy character. — London Lancet, Nov. 
 21, 1857. 
 
 We believe that this book will be read with interest. 
 It is calculated to impart instruction to all of us. — 
 Brit, and For. Medico-Chirurg . Meview, April, 1858. 
 
 J. HUGHES BENNETT, M. D., F.R.S.E., 
 
 Professor of Clinical Medicine in the ITniversily 
 of Edinburgh, &e. 
 
 Ill one small octavo volume, extra cloth, with beau- 
 tiful illustrations. $1 '25. 
 
 Tubercular Cavity in the act of Healing. 
 
MEDICAL AND SCIENTIFIC PUBLICATIONS. 
 
 43 
 
 RICORD AND HUNTER ON VENEREAL— New Edition, Now Ready (1869). 
 
 A TREATISE 01 THE"yENEREAL DISEASE. 
 
 BY JOHN HUNTER, F. K S., &c. 
 
 With Copious Additions by PH. RICORD, M. D. 
 
 Second Edition, containing a resume of Ricord's recent Lectures on Chancre. 
 
 Translated and Edited, witu Notes, by FREEMAN J. BUMSTEAD, M.D., 
 
 Lecturer on Venereal at the College of Physicians and Surgeons, New York. 
 
 Ill 07ie large and handsome octavo volume of 550 pages, with eight plates ; extra cloth, $3 25. 
 
 "M. Ricord's annotations to Hunters Treatise on the Venereal Disease were first published 
 at Paris, in 1840, in connection with Dr. G. Richelot's translation of the work, including '.he 
 contributions of Sir Everard Home and Mr. Babington. In a second edition, which has recently 
 appeared, M. Ricord has thoroughly revised his part of the work, bringing it up to the knowledge 
 of the present day, and so materially increasing it that it now constitutes full one-third of the 
 voltirae. This publication has been received with great favor by the French, both because it 
 has placed within their reach an important work of Hunter, and also because it is the only recent 
 practical work which M. Ricord has published, no edition of his Traite des Maladies Veneri- 
 ennes having appeared for the last fifteen years." — Translator'' s Preface. 
 
 The addition, in the present edition, of the material contained in the "Lectures on Chancre," 
 published a few months since by M. Ricord, renders this work the most complete embodiment 
 of the views of the great French syphilographer that has 'vet been given to the profession, while 
 the editor has further endeavored to present all other matter of interest that has appeared since 
 the publication of the first edition. The volume may therefore be regarded as a complete work 
 of reference on the subject in which the practitioner may at all times be certain of finding an 
 elucidation of doubtful questions either of theory or practice. 
 
 Every one will recognize the attractiveness and 
 value which this work derives from thus presenting 
 the opinions of these two masters side by side. But, 
 it must be admitted, what has made the fortune of 
 the book, is the fact that it contains the " most com- 
 plete embodiment of the veritable doctrines of the 
 Hopital du Midi," which has ever been made public. 
 The doctrinal ideas of M. Ricord, ideas which, if not 
 universally adopted, are incontestably dominant, have 
 heretofore only been interpreted by more or less skilful 
 
 secretaries, sometimes accredited and sometimes not. 
 Tn the notes to Hunter, the master substitutes himself 
 for his interpreters, and gives his original thoughts to 
 the world, in a summary form it is true, but in a lucid 
 and perfectly intelligible manner. In conclusion, we 
 can say that this is incontestably the best treatise on 
 syphilis with which we are acquainted, and, as we do 
 not often employ the phrase, we may be excused for 
 expressing the hope that it may find a place in the 
 library of every physician. — Va. Med. and Surg. Journ. 
 
 Also — HUNTER'S COMPLETE WORKS. 
 
 numerous Illustrations; leather, $10 00. 
 
 In four octavo volumes, with 
 
 RICORD'S 
 
 LETTERS ON SYPHILIS, 
 
 Addressed to the Chief Editor of the Union Medicale. With an Introduction by Amedee 
 Latour. Translated by W. P. Lattimore, M. D. In one neat octavo volume, extra cloth, $2. 
 
 Lately Published. 
 
 THE MODERN TRE/VTMENFoF SYPHILITIC DISEASES, 
 
 BOTH PRIMARY AND SECONDARY. 
 
 COMPRISING THE 
 
 Treatment of Constitutional and confirmed Syphilis by a safe and successful Method. 
 
 WITH NUMEROUS CASES, FORMULA, AND CLINICAL OBSERVATIONS. 
 BY LANGSTON PARKER, 
 
 Surgeon to the Queen's Hospital, Birmingham. 
 
 Erom the Third and entirely rewritten London Edition. 
 
 Ill one neat octavo vohime of over 3QQ pages, extra cloth, $1 75. 
 
 The third edition of Mr. Parker's work constitutes, I has contrived to emhody in it everything of import- 
 we must say, an excellent practical treatise, the suh- auce respecting syphilis and its treatment. — Dublin 
 ject is remarkably well arranged; indeed, the author | Medical Press. 
 
 LECTURES ON THE PRINCIPLES AND METHODS OF MEDICAL OB- 
 SERVATION AND RESEARCH. For the use of Advanced Students and Junior Practi- 
 tioners. By Thomas Laycock, M. D., F. R. S. E., Professor of Practical and Clinical Medi- 
 cine in the University of Edinburgh, etc. In one very neat royal 12mo. vol., extra cloth, $1. 
 
44 
 
 BLANCHARD AND LEA'S 
 
 NEW AND MUCH IMPROVED EDITION— (Just Issued.) 
 
 THE HISTORY, DIAGNOSIS, AND TREATMENT OP THE 
 
 FEYERS OF THE UNITED STATES. 
 
 BY ELISHA BARTLETT, M. D., 
 
 Late Professor of Materia Medica, &c., in the College of Physicians and Surgeons, New York. 
 
 J^ourtlj ibttion, ^Itbxscb 
 BY ALONZO CLARK, M. D., 
 
 Professor of Pathology and Practical Medicine in the College of Physicians and Surgeons, New York. 
 
 In one large and handsome octavo volume, of over six hundred pages ; extra cloth, $3 00. 
 
 From the Editor'' s Preface. 
 " The question maybe fairly raised whether any book in our profession illustrates more clearly 
 the beauties of sound reasoning, and the advantages of vigorous generalization from carefully 
 selected facts. Certainly no author ever brought to his labor a more high-minded purpose of 
 representing the truth, in its simplicity and m its fulness, w^hile (ew have been possessed of 
 higher gifts to discern, and gracefully to exhibit it. Had I been prepared by previous reading 
 for the duty which the partiality of Dr. Bartlett assigned to me, of preparing this edition for the 
 press, the labor would have been inconsiderable. As it is, I have read extensively, to learn 
 how little that the book contains can be advantageously altered. Considerable matter has 
 been added, it is true, because new facts have been observed, and new opinions have been ex- 
 pressed, which both add to our knowledge, and suggest new topics for investigation. This 1 
 have endeavored to select, and so far as it is original to write, with the same re>pect for truth, 
 and desire for usefulness, which influenced the mind of my endeared friend, the accomplished 
 author." 
 
 Carefully revised by Professor Clark, who has introduced whatever is new in the literature 
 of this branch of medical science since the appearance of the last edition, embodying the results 
 of the observations and researches of Drake, La Roche, Flint, Barton, Dickson, Fenner, 
 Peacocke, and others, this volume will be found fully brought up to the present day, and emi- 
 nently worthy a continuance of the confidence of the profession. 
 
 The masterly and elegant treatise by Dr. Bartlett is 
 invaluable to the American student and practitioner. 
 — Dr. Holmes's Report to the Nat. Med. Association. 
 
 We regard it, from the examination we have made 
 of it, the best work on fevers extant in our language, 
 and as such cordially recommend it to the medical 
 public. — St. Louis Medical and Surgical Journal. 
 
 Take it altogether, it is the most complete history of 
 our fevers which has yet been published, and every 
 practitioner should avail himself of its contents. — The 
 Western Lancet. 
 
 Of the value and importance of such a work, it is 
 needless here to speak; the profession of the United 
 States owe much to the author for the very able 
 volume which he has presented to them, and for the 
 careful and judicious manner in which he has executed 
 his task. No one volume with which we are acquainted 
 contains so complete a history of our fevers as this. 
 To Dr. Bartlett we owe our best thanks for the very 
 able volume he has given us, as embodying certainly 
 the most complete, methodical, and satisfactory ac- 
 count of our fevers anywhere to be met with. — The 
 Charleston Med. Journal and Review. 
 
 THE HTJ]M:A.N BHA-IN; 
 
 WITH A 
 
 DESCRIPTION OF THE TYPICAL FORMS OF BRAIN IN THE ANIMAL KINGDOM. 
 
 BY SAMUEL SOLLY, F. R. S., 
 
 Senior Assistant Surgeon to St. Thomas's 
 Hospital, &c. 
 
 jFrom i\t snav.'ii I/onlion jcIJittDit. 
 
 WITH 
 
 ONE HUNDRED AND EIGHTEEN 
 
 ELABORATE ILLUSTRATIONS 
 
 ON WOOD. 
 
 In one handsome octavo volume, of 
 
 about five hundred pages, 
 
 extra cloth, %2 00. 
 
 Inferior Surfaceofthe Cerebellum. 
 
MEDICAL AND SCIENTIFIC PUBLICATIONS. 
 
 45 
 
 Just Issued. 
 
 ATLAS or CUTANEOUS DISEASES. 
 
 BY J. MOORE NELIGAN, M. D., M. R. I. A., &c. 
 
 Willi Splendid Colored Plates, presenting nearly one hundred elaborate representations 
 of Disease, colored after nature. 
 
 Ill one very handsome quarto volume., extra doth., price $4 50. 
 Also now ready, by the same Author. 
 
 A PRACTICAL TREATISE ON DISEASES OF THE SKIN. 
 
 SECOND AMERICAN EDITION. 
 
 In one neat royal 12mo. volume, extra cloth, of 334 pages, price $1. 
 These two volumes, constituting- together a complete work on the diagnos^is. pathology, and 
 treatment of cutaneous affections, will be forwarded by mail on receipt of $5. 
 
 A compend which will very much aid the practi- 
 tioner in this difficult branch of diagnosis. Taken 
 with the beautiful plates of the Atlas, which are re- 
 markable for their accuracy and beauty of coloring, 
 it constitutes a very valuable addition to the library 
 of a practical man. — Buffalo Med. Journal. 
 
 The lithographs are so colored as to be true and 
 faithful representations of these ninety varieties of a 
 class of diseases whose exact diagnosis is thus made 
 plain and easy, and which, in the absence of such aid 
 or a long and attentive study, is so difficult that very 
 few praotitioners seriously attempt it. The work is 
 cheap, and no practitioner ambitious of a high profes- 
 sional status can afford to dispense with such helps. — 
 JVashviUe Journal of Medicine. 
 
 Neligan's Atlas of Cutaneous Diseases supplies a long 
 
 existent desideratum much felt by the largest class 
 of our profession. It presents, in quarto size, 16 
 plates, each containing from 3 to 6 figures, and form- 
 ing in all a total of 90 distinct representations of the 
 different species of skin affections, grouped together in 
 genera or families. The illustrations have been taken 
 from nature, and have been copied with such fidelity 
 that they present a striking picture of life; in which 
 the reduced scale aptly serves to give, at a coup d'ceil, 
 the remarkablepeculiaritiesofeach individual variety. 
 And while thus the disease is rendered more definable, 
 there is yet no loss of proportion incurred by the ne- 
 cessary concentration. Each figure is highly colored, 
 and so truthful has the artist been that the most fas- 
 tidious observer could not justly take exception to the 
 correctness of the execution of the pictures under his 
 scrutiny. — Montreal Med. Chronicle. 
 
 Ne-w and enlarged Edition — No^w Ready (June, 1859). 
 
 UEINARYT3EP0SITS; 
 
 THEIR DIAGNOSIS, PATHOLOGY, AND THERAPEUTICAL INDICATIONS. 
 
 BY GOLDING BIRD, M. D., F. R. S., &c. 
 
 Edited bt EDMUND LLOYD BIRKETT, M. D., &c. 
 
 A New American, from the Fifth London Edition. 
 WITH EIGHTY ILLUSTRATIONS. 
 In one handsoTne octavo volume, extra cloth, of 382 pages, $2 00. 
 The death of Dr. Bird has rendered it necessary to entrust the revision of (he present edition 
 to other hands, and in his performance of the duty thus devolving on him, Dr. Birkett has sedu- 
 lou^ly endeavored to carry out the author's plan by introducing such new matter and modifica- 
 tions of the text as the progress of science has 
 called for. Notwithstanding the utmost care 
 to keep the work within a reasonable compass, 
 these additions have resulted in a considerable 
 enlargement. It is, therefore, hoped that it will 
 be found fulJy up to the present condition of the 
 subject, and that the reputation of the volume 
 as a clear, complete, and compendious manual, 
 will be fully maintained. 
 
 It can scarcely be necessary for us to say anything 
 of the merits of this well-known Treatise, which so ad- 
 mirably brings into practical application the results 
 of those microscopical and chemical researches regard- 
 ing the physiology and pathology of the urinary se- 
 cretion, which have contributed so much to the 
 increase of our diagnostic powers, and to the extension 
 and satisfactory employment of our therapeutic re- 
 sources. In the preparation of this new edition of his 
 work, it is obvious that Dr. Golding Bird has spared 
 no pains to render it a faithful representation of the 
 present state of scientific knowledge on the subject it 
 embraces. — British and Foreign Med.-Chir. Review. 
 Crystals of Phosphate of Soda. 
 
 MANUALS ON THE BLOOD AND URINE.— By John | FRICK ON THE URINE.— Renal Affections, their 
 William Griffith, M. D,, G. Owen Reese, M. D., and | Diagnosis and Pathology. In one handsome volume, 
 Alfred Markwick. In one large 12mo. volume, extra I royal 12mo., with illustrations, 75 cents, 
 cloth, of 460 pages, with Plates, $1 25. I 
 
46 
 
 BLANCHARD AND LEA'S 
 
 The Standard work on the Skin— (Just Issued.) 
 
 ON i:>isea-Se:s~of the skidst. 
 
 BY ERASMUS WILSON, F. R. S., 
 
 Author of "A System of Human Anatomy," &c. 
 
 S;ije Joitrtlj anb ^nlargeb '^mmcmx, from tljc last anb |mpra&cb ITonbon (Bbition. 
 
 In, one large octavo vohime, of 650 pages, extra cloth, $2 75. 
 
 This volume, in passing for tlie fourth time through the hands of the author, has received a 
 careful revision, and has been greatly enlarged and improved. About one hundred and fifty 
 pages have been added, including new chapters on Classification, on General Pathology, on 
 General Therapeutics, on Furuncular Eruptions, and on Diseases of the Nails, besides extensive 
 •additions throughout the text, wherever they have seemed desirable, either from former omis- 
 sions or from the progress of science and the increased experience of the author. Appended to 
 the volume will also now be found a collection of Selected FoemuLjE, consisting for the most 
 part of prescriptions of which the author has tested the value. 
 
 Thus perfected and brought up to the latest moment, this work cannot fail to maintain its 
 character as the standard authority on this important and perplexing class of affections. 
 
 When the first edition of this work appeared, about 
 fourteen years ago, Mr. Erasmus Wilson had already 
 given some years to the study of Diseases of the Skin, 
 and he then expressed his intention of devoting his 
 future life to the elucidation of this particular branch 
 of Medical Science. In the present edition Mr. Wil- 
 son presents us with the results of his matured ex- 
 perience gained after an extensive acquaintance with 
 the pathology and treatment of cutaneous affections ; 
 and we have now before us not merely a reprint of 
 his former publications, but an entirely new and re- 
 written volume. Thus, the whole history of the dis- 
 eases affecting the skin, whether they originate in 
 
 that structure or are the mere manifestations of de- 
 rangement of internal organs, is brought under notice, 
 and the book includes a mass of information which 
 is spread over a great part of the domain of Medical 
 and Surgical Pathology We can safely recommend 
 it to the profession as the best work on the subject now 
 in existence in the English language. — London Med. 
 Times and Gazette, March 28, 1857. 
 
 The " Diseases of the Skin," by Mr. Erasmus Wilson, 
 may now be regarded as the standard work in tliat 
 department of medical literature. — Medico-Chirurg . 
 Review. 
 
 Also, Now Ready. 
 
 A SERIES OF PLATES IllUSTRATING "WILSON ON DISEASES OF THE SKIN." 
 
 CONSISTING OF NINETEEN BEAUTIFULLY EXECUTED PLATES, OF WHICH TWELVE AEE EXQUISITELY COLORED. 
 
 Presenting the Normal Anatomy and Pathology of the S/dn, and embracing accurate repre- 
 sentations of about one hundred varieties of Disease, m,ost of them, the size of 
 Nature. Price, in extra cloth, $4 25. 
 
 For beauty of drawing, and accuracy and finish of colorinff, these plates are confidently pre- 
 sented as superior to anything of the kind as yet issued in this country. 
 
 The plates by which this edition is accompanied 
 leave nothing to be desired, so far as excellence of 
 delineation and perfect accuracy of illustration are 
 concerned. — Medicc-Chirurgical Review. 
 
 Of these plates it is impossible to speak too highly. 
 
 The representations of the various forms of cutaneous 
 disease are singularly accurate, and the coloring ex- 
 ceeds almost anything we have met with in point of 
 delicacy and finish." — British and Foreign Medical 
 Review. 
 
 Epidermal horn, caused by Disease 
 of the Oil Glands. 
 
 By the same Author— (Lately Issued.) 
 
 HEALTHY SKIN: 
 
 A Popular Treatise on the Skin and Hair, their 
 Preservation and Management. 
 
 SECOND AMERICAN, PROM THE POUKTH AND 
 REVISED LONDON EDITION. 
 
 J>i o?ie neat royal 12mo. volum,e, of about three htm- 
 
 dred pages, with numerous Illustrations ; 
 
 extra cloth, or flexible cloth, $1 00 ; 
 
 paper covers, 75 ce7it . 
 
 The student will be delighted to find his labors so much 
 facilitated; and a few hours of agreeable society with a moat 
 pleasantly-written book will do more to make him acquainted 
 with a class of obscure diseases than all that has been pre- 
 viously written on the subject. — London Lancet. 
 
 By the same Author. 
 ON CONSTITUTIONAL AND HEREDITARY SYPHILIS, AND ON 
 
 SYPHILITIC EHUPTIONS. In one beautifully printed octavo volume, with four exquisite 
 colored plates, presenting more than thirty varieties of Syphilitic Eruptions ; extra cloth, $2 25. 
 
MEDICAL AND SCIENTIFIC PUBLICATIONS. 
 
 47 
 
 New and inipioved Edition — Now Ready (1859), 
 
 A PRACTICAL TREATISE 
 
 ON THE DISEASES OF CHILDREN. 
 
 BY D. FRANCIS CONDIE, M. D. 
 
 FIFTH EDITION, REVISED AND ENLARGED. 
 
 In one large octavo volume of nearly eight hundred pages ; leather, $3 25. 
 
 From the Author's Preface. 
 
 To present a complete and faithful exposition of the pathology and therapeutics of the mala- 
 dies incident to the earlier stages of existence — a full and exact account of the diseases of infancy 
 and childhood — has been the aim of the author of the present treatise. For the furtherance of 
 this object, in the preparation of a fifth edition, the entire work has been subjected to a careful 
 and thorough revision; a considerable portion of it has been entirely rewritten, and several new 
 chapters have been added. 
 
 In the different sections will be found incorporated every important observation in reference 
 to the diseases of which they treat, that lias been recorded since the appearance of the last edi- 
 tion ; and in the several new chapters, an account of some affections omitted in former editions, 
 and for the accurate description and satisfactory management of which we are indebted mainly 
 to the labors of recent observers. 
 
 Tlie value of works by native authors on the diseases 
 which the physician is called upon to combat, will be 
 appreciated by all ; and the work of Dr. Condie has 
 gained for itself the character of a safe guide for stu- 
 dents, and a \iseful work for consultation by those en- 
 gaged in practice. — Nnu York Medical Times. 
 
 In the department of infantile therapeutics, the work 
 of Dr. Condie is considered one of the best which has 
 been published in the English language. — The Stetho- 
 scope. 
 
 As we said before, we do not know of a better book 
 on Diseases of Children, and to a large part of its re- 
 commendations we yield an unhesitating concurrence. 
 — Buffalo Medical Journal. 
 
 The work of Dr. Condie is unquestionably a very 
 able one. It is practical in its character, as its title 
 imports; but the practical precepts recommended in 
 it are based, as all practice should be, upon a familiar 
 knowledge of disease. The opportunities of Dr. Con- 
 die for the practical study of the diseases of children 
 have been great, and his work is a proof that they have 
 not been thrown away. He has read much, but ob- 
 served more; and we think that we may safely say 
 that the American student cannot tind, in his own 
 language, a better book upon the subject of which it 
 treats. — Am. Journal Medical Sciences. 
 
 To call the attention of the medical fraternity to a 
 new edition of this American medical classic, seems 
 almost a work of supererogation. The name of Dr. 
 Condie is too well known, and his influence too gene- 
 rally felt and acknowledged in the department of Pa- 
 thology to which the present work refers, to require 
 other than a very brief notice of this new edition. — 
 The Peninsxdar Journal of Medicine. 
 
 Taken as a whole, in our judgment. Dr. Condie's 
 Treatise is one from the perusal of which the practi- 
 tioner in this country will rise with the greatest sa- 
 tisfaction. — Western Journal of Medicitie and Surgery. 
 
 One of the best works upon the Diseases of Children 
 in the English language. — Western Lancet. 
 
 We feel assured from actual experience that no phy- 
 sician's library can be complete without a copy of this 
 work. — iV". T. Jounial of Medicine. 
 
 Perhaps the most full and complete work now before 
 the profession of the United States; indeed, we may 
 say in the English language. It is vastly superior to 
 most of its predecessors. — Transylvania Med. Journal. 
 
 A veritable ptediatric encyclopedia, and an honor 
 to American medical literature. — Ohio Medical and 
 Surgical Journal. 
 
 The author's great experience, extensive reading, 
 and familiarity with foreign languages, peculiarly fit 
 him for the execution of such a work ; and its value 
 is abundantly proved by the numerous editions which 
 it has reached in a very short period. It is character- 
 ized by great clearness and lucidity of style and ar- 
 rangement, sound pathological views, and precise 
 and plain therapeutical directions. — Medical Examiner. 
 
 To the American practitioner. Dr. Condie's remarks 
 on the di.^eases of children will be invaluable, and we 
 accordingly advise those who have failed to read this 
 work to procure a copy, and make themselves familiar 
 with its sound principles. — The New Orleans Medical 
 and Surgical Journal. 
 
 LECTUKES ON THE 
 
 DISEASES OF INFANCY AND CHILDHOOD. 
 
 BY CHARLES WEST, M. D., 
 
 Physician to the Hospital for Sick Children, &c. 
 
 Second American, from the Second and Enlarged London Edition. 
 
 In one neat octavo volume of nearly 500 large pages; extra cloth, $2. 
 
 In taking leave of Dr. West, we can scarcely do more 
 than reiterate our former praise of him. We have 
 given, we fear, but a very faint notion of the scope of 
 his work, and of its excellent execution. It is one 
 standing by itself upon its important subject in our 
 language — unapproached, unrivalled His knowledge 
 of what others have done is equalled only by his own 
 extensive experience ; and the results of both are com- 
 bined in his valuable practical lectures now offered for 
 the guidance of others. — Brit, and For. Med.-Ckirurg. 
 Jteview. 
 
 The book has about it that practical common sense 
 character which is always acceptable to the practition- 
 er of medicine, whilst the immense experience of Dr. 
 West, derived from his connection with the London 
 Hospital for Sick Children, gives to him opportunities 
 for the minute observation of the diseases incident to 
 childhood, such as no private practice can offer. We 
 would especially recommend the careful study of these 
 lectures to the medical student who is preparing him- 
 self for general practice. — Va Med. and Surg. Journal. 
 
48 BLANCHARD AND LEA'S 
 
 New and Enlarged Edition — (Just Issued.) 
 
 ON THE DISEASES OF INFANTS AND CHILDREN. 
 
 BY FLEETWOOD CHURCHILL, M. D., M. R. I. A., 
 
 Author of " Theory and Practice of Midwifery," '• Diseases of Females," &e. &c. 
 Second American Edition, Enlarged and Revised by the Anthor. 
 
 Edited, ttith Notes, by W. V. KEATING, M. D. 
 
 In one large and handsome octavo volume of over 100 pages ; leather, $3 25; extra doth, $3. 
 
 The thorough manner in which Dr. Churchill has revised this work may be estimated from 
 the fact that not only has a considerable portion been rewritten, but that in all the present edition 
 contains about one-third more matter than the former. Besides an enlargement in the size of the 
 page, the volume has been increased by about seventy-five pages, notwithstanding which the 
 price has been maintained at the former very moderate rate. 
 
 Few -works devoted to the same subject will be comes to us with its value greatly enhanced, not 
 found, in fact, to excel the one before us, in extent of merely by bein<; carefully revi.-ed throughout, but 
 research, copiousness of reference, and fulness and also by the addition of several entire chapters ; on 
 accuracy of detail. It will constitute a valuable and Atelectasis Pulmonum, Pulmonary Phthisis, Tabes 
 reliable guide to the knowledge of the several morbid Mesenterica. (Edema of the Cellular Tissue, Typhoid 
 conditions incident to infancy and childhood, their Fever, and Infantile Syphilis. The volume is a most 
 causes, semeiology, seats, character, and progress, and valuable addition to this department of medical sci- 
 the means best adapted for their alleviation and cure, ence. — Boston Med. and Surg. Jowtial, Sept. 1856. 
 equally suitable to the student, as to the practitioner . . •. , . •. 
 
 who would render himself familiar with the lights It is with pleasure we notice the appearance of the 
 which recent investigation and discoveries have second edition of this excellent work on the diseases 
 thrown upon each and all of these particulars.— J»i. , of Children. It has been carefully revised by the au- 
 Journ. Med. Sciences. Oct. 1856. thor. and all the information added which has been de- 
 
 I rived from recent researches. Every paragraph, says 
 
 Dr. Churchill is well known as the author of various ' the author, has been carefully gone over with a view 
 works on obstetrics and the diseases of women. Like to correction, and suggestions made by reviewers have 
 them, this contribution to infantile therapeutics is been carefully weighed, and adopted when correct, 
 especially useful for the careful and extensive collec- ^ Several entire new chapters, and portions of chapters, 
 tion of material bearing upon the subject. As a book ' have been added, and especial reference has been had 
 of reference, it will be often sought for, whilst its emi- to American authorities so as to adapt it to the wants 
 nently practical character will make it an admirable of this country. We feel that it is no more than jus- 
 manual for the student. We are compelled for want tice to add our recommendation, most cordially, of this 
 of space, to refrain from making as many extracts as work, as being among the best we have on this sub- 
 we would like to do, and will close our notice of the I ject. — Cincinno.ti Medical Observer, Oct. 1856. 
 work by heartilv recommending it both to the student I „, , , . ^ ,, , , ^ -,, ^ ^ , 
 
 and the practitioner.— Fu. Med. Journal, Sept. 1856. ^he book is fully posted up and will be found a va- 
 
 luable addition to the practitioner s library. — Southern 
 
 This new edition of the work of a favorite author | Med. and Surg. Journal, Nov. 1856. 
 
 A TREATISE ON THE 
 
 PHYSICAL AXD MEDICAL TPiEAT3IENT OF CHEDREN. 
 
 BY WILLIAM P. DEWEES, M. D. 
 Tenth Edition. 
 
 In one octavo volume of 548 pages ; extra cloth, $2 80. 
 
 Tenth Edition. 
 
 A TREATISE ON THE DISEASES OF FEMALES. 
 
 BY WILLIAM P. DEWEES, M. D. 
 
 hi one octavo volume of five hundred and thirty-two pages, vAth plates, S'i 00. 
 
 Just Issued. 
 
 ON THE CONSTITUTIONAL TREATMENT 
 
 OF FEM:A.LE I3ISEA.SES. 
 
 BY EDWARD RIGBY, M. D., 
 
 Senior Physician to the General Lying-in Hospital, &c.; Author of "A System of Midwifery," &c. 
 In one neat royal 12mo. volume of 250 pages; extra cloth, $1. 
 
MEDICAL AND SCIENTIFIC PUBLICATIONS. 
 
 49 
 
 New axid Improved Edition— Now Ready (June, 1859). 
 
 ¥OMA¥; HER DISEASES AND REMEDIES. 
 
 A SERIES OF LETTERS TO HIS CLASS. 
 BY CHARLES D. MEIGS, M. D., 
 
 Professor of Midwifery, and Diseases of Women and Cliildren, in the Jefferson Medical College, Philadelphia. 
 FOURTH EDITION, REVISED. 
 hi one large and liandsome octavo volume of over seven hundred fages ; leather^ $3 60. 
 The gratifying appreciation of his labors, as evinced by the exhaustion of three large impres- 
 sions of this work, has not been lost upon the author, wtio has endeavored in everj' way to ren- 
 der it worthy of the favor with which it has been received. The opportunity thus afforded for 
 another revision has been improved, and the work is now presented as in every way superior to 
 its predecessors, additions and alterations having been made wherever the advance of science 
 has rendered them desirable. The typographical execution of the work will also be found to 
 have undergone a similar improvement, and the volume, it is hoped, will be found in all respects 
 worthy to maintain the position it has acquired as the standard American text-book on the Dis- 
 eases oi Females. A few notices of the previous editions are appended. 
 
 On its first appearance we had occasion to speak of 
 it in terms of merited commendation. In announcing 
 the third edition, it is only necessary to say that it 
 has been thoroughly revised and much enlarged by 
 its distinguished author so as greatly to enhance its 
 value and usefulness. — St. Louis Med. and Surg. Journ. 
 
 Keplete with sound practical views, and evidently 
 the production of a man of vast experience and tho- 
 roughly conversant with the subject. — Medical Chro- 
 nicle. 
 
 He is a bold thinker, and possesses more originality 
 of thought and style than almost any American writer 
 on medical subjects. If he is not an elegant writer, 
 there is at least a freshness — a raciness in his mode 
 of expressing himself— that cannot fail to draw the 
 reader after him even to the close of his work ; j'ou 
 cannot nod over his pages; he stimulates rather than 
 narcotises your senses, and the reader cannot lay aside 
 these letters when once he enters into their merits. 
 This the second edition is much amended and enlarged, 
 and affords abundant evidence of the author's talents 
 and industrj'. — N. 0. Medical and Surgical Journal. 
 
 The practical writings of Dr. Meigs are second to 
 none. — Ttie N. T. Journal of Medicine. 
 
 The excellent practical directions contained in this 
 volume, give it great utility, which we trust will not 
 be lost upon our older colleagues: with some conden- 
 sation, indeed, we should tliink it well adapted for 
 translation into German. — Zeitschriftfur die Gesammte 
 Medecin. 
 
 The merits of the first edition of this work were so 
 generally appreciated, and with such a high degree of 
 favor by the medical profession throughout the Union, 
 that we are not surprised in seeing a second edition of 
 it. It is a standard work on the diseases of females, 
 and in many respects is one of the very best of its 
 kind in the English language. Upon the appearance 
 of the first edition, we gave the work a cordial recep- 
 tion, and spoke of it in the warmest terms of commen- 
 dation. Time has not changed the favorable estimate 
 we placed upon it. but has rather increased our con- 
 
 victions of its superlative merits. But we do not now 
 deem it necessary to say more than to commend this 
 work, on the diseases of women, and the remedies for 
 them, to the attention of those practitioners who have 
 not supplied themselves with it. The most select 
 library would be imperfect without it. — The Western 
 Journal of Medicine and Surgery. 
 
 There is an off-hand fervor, a glow and a warm- 
 heartedness infecting the effort of Dr. Meigs, which is 
 entirely captivating, and which absolutely hurries the 
 reader through from beginning to end. Besides, the 
 book teems with solid instruction, and it shows the 
 very highest evidence of ability, viz., the clearness 
 with which the information is presented. We know 
 of no better test of one's understanding a subject than 
 the evidence of the power of lucidly explaining it. 
 The most elementary, as well as the obscurest subjects, 
 under the pencil of Prof. Meigs, are isolated and made 
 to stand out in such bold relief, as to produce distinct 
 impressions upon the mind and memory of the reader. 
 — The Charleston Medical Journal. 
 
 That he has succeeded in writing a readable work, 
 in our estimation, we have the best practical evidence 
 in the fact, that, in spite of a deliberate resolve to 
 postpone its perusal, having other more pressing 
 matters on hand, we found ourselves taking it up day 
 after day, at our leisure moments, until the volume 
 was finished. If we may judge of others by our own 
 experience, the student and practitioner will find it an 
 attractive book. The character of the work is infi- 
 nitely more pleasing to us than if written in a tame, 
 spiritless manner, albeit, in the latter case, it were less 
 obnoxious to criticism. We like to see the man in the 
 book. It shows the author to be a scholar, a man of 
 genius, and as regards matter, when it is considered 
 that Prof M. ranks among the most talented and 
 learned of the profession of this country, and, we may 
 safely add, of any country, and, moreover, that his 
 experience in his particular province has been im- 
 mense, it can hardly appear otherwise than that what 
 he may write on the diseases of females shall be de- 
 serving of most respectful attention. — Buffalo Medical 
 Journal. 
 
 By the same Author. 
 
 A TREATISE ON ACUTeTnD CHROKIC DISEASES 
 
 OF THE NECK OF THE UTERUS. 
 
 With numerous Plates, drawn and colored from Nature in the highest style of art. 
 In one very handsorae octavo volume ; extra doth., $4 50. 
 
 A TREATISE ON THE 
 
 DISEASES AND SPECIAL HYGIENE OE EEMALES. 
 
 By CoLOMBAT De L'Isere. Translated from the French, with additions, by Charles D. Meigs, 
 M. D., Professor of Midwifery, and Diseases of Women and Children, in the Jefferson Medi- 
 cal College, Philadelphia. A new and revised edition. In one octavo volume of over 700 
 pages, with numerous illustrations ; extra cloth, $3 50. 
 
 4 
 
50 
 
 BLANCHARD AND I.EA'S 
 
 Enlarged and Illustrated Edition— Just Issued. 
 
 VERY HANDSOME 
 
 I OCTAVO VOLUME, OF OVER 
 
 SEVEN HUNDRED AND FIFTY 
 
 LARGE PAGES. 
 
 WITH 
 
 Numerous 
 
 Illustrations. 
 
 LEATHER, 
 
 Price $3 00. 
 
 Prolapsus Vkri. 
 
 ON THE DISEASES OF WOMEN, 
 
 mCLUDI^^G DISEASES OF PREGNA^^CY AND CHILDBED. 
 
 BY FLEETWOOD CHURCHILL, M. D., M. R. L A., 
 
 Author of "Diseases of Infants and Children," "Theory and Practice of Midwifery," &c &c. 
 
 Sixth American Edition, extensively Enlarged and Revised by the Author. 
 
 W.iX\ NotfS anlJ gLtilJitions 
 
 BY D. FRANCIS CONDIE, M. D , 
 
 Author of "A Practical Treatise on Diseases of Children," &c. 
 
 On no former edition has the author devoted more labor to render the work a complete and 
 satisfactory resume of the existing state of knowledge on the important questions under con- 
 sideration. To effect this, extensive additions have been required, some additional chapters 
 inserted, and many portions rewritten A handsome series of original illustrations of the more 
 important pathological conditions has been prepared, while the mechanical execution of the 
 volume will be found greatly superior to any former edition. 
 
 Former editions of this work have been noticed in 
 previous numbers of the Journal. The sentiments of 
 high commendation expressed in those notices, have 
 only to be repeated in this : not from the fact that the 
 profession at large are not aware of the high merits 
 which this work really possesses, but from a desire to 
 see the principles and doctrines therein contained 
 more generally recognized, and more universally car- 
 ried out in practice. — N. Y. Journal of Medicine. 
 
 We know of no author who deserves that approba- 
 tion, on " the diseases of females," to the same extent 
 that Dr. Oh archill does. His, indeed, is the only tho- 
 rough treatise we know of on the subject; and it may 
 be commended to practitioners and students as a mas- 
 terpiece in its particular department. The former 
 editions of this work have been commended strongly 
 in this journal, and they have won their way to an 
 extended, and a well-deserved popularity. This fifth 
 edition, before us, is well calculated to maintain Dr. 
 
 Churchill's high reputation. It was revised and en- 
 larged by the author, for his American publishers, 
 and it seems to us that there is scarcely any species of 
 desirable information on its subjects that may not be 
 found in this work. — The We^te,rn Journal of Medicine 
 and Surgery. 
 
 "We are gratified to announce a new and revised edi- 
 tion of Dr. Churchill's valuable work on the diseases 
 of females. We have ever regarded it as one of the 
 very best works on the subjects embraced within its 
 scope, in the English language; and the present edi- 
 tion, enlarged and revised by the author, renders it 
 still more entitled to the confidence of the profession. 
 — The Western Lo.ncet. 
 
 As a comprehensive manual for students, or a work 
 of reference for practitioners, we only speak with com- 
 mon justice when we say that it surpasses any other 
 that has ever issued on the same subject from the 
 British press. — Ttie Dublin Quarterly Journal. 
 
 By the same Author. 
 
 ESSAYS ON THE PUERPERAL FEVER, AND OTHER DISEASES PECULIAR TO 
 WOMEN. Selected from the writings of Briti-h Authors previous to the close of the Eight- 
 eenth Century. In one neat octavo volume, of about 450 pages, extra cloth, $2 50. 
 
MEDICAL AND SCIENTIFIC PUBLICATIONS. 
 
 51 
 
 MEIGS ON PUERPERAL FEVER— (Lately Published.) 
 
 ON THE NATURE, SIGNS, AND TREATMENT 
 
 OF CHILDBED FEVERS: 
 
 IN A SERIES OF LETTERS ADDRESSED TO THE STUDENTS OF HIS CLASS. 
 BY CHARLES D. MEIGS, M. D., 
 
 Professor of Midwifery and Diseases of Women and Children in the Jefferson Medical College, Philadelphia. 
 hi 07ie very liandsome octavo volume of 362 pages ; extra cloth, $2 50. 
 
 The author, a practitioner of more than forty years, 
 has collected the best and most reliable opinions of 
 many writers on this disease, and applying to them 
 the test of clinical experience, has produced a volume 
 superior in many respects to any which has heretofore 
 come from his pen As the results of a critical inquiry 
 into the literature of the disease and a large and long 
 experience in practice, this volume will be received by 
 the profession with distinguished favor, and we feel 
 warranted in commending it to the favorable attention 
 of our readers. — N. Y. Journal of Medicine. 
 
 The present is upon one of the most diflBcult subjects 
 in obstetrics, and we feel bound to say that as a whole 
 it is superior to any other work upon the same subject. 
 — Edinburgh Med. Journal. 
 
 We cordially recommend it to our readers as a work 
 abounding in practical good sense, and sound patho- 
 logical and therapeutical views. — Si. Louis Med. and 
 Surg. Journal. 
 
 The instructive and interesting author of this work, 
 whose previous labors in the department of medicine 
 which he so sedulously cultivates, have placed his 
 countrymen under deep and abiding obligations, again 
 challenges their admiration in the fresh and vigorous, 
 attractive and racy pages before us. It is a delectable 
 book. * * * This treatise upon childbed fevers 
 will have an extensive sale, being destined, as it de- 
 serves, to find a place in the library of every practi- 
 tioner who scorns to lag in the rear of his brethren. 
 — Nashville Journal of Medicine and Surgery. 
 
 Just Issued. 
 
 ON SOME DISEASES OF WOMEN 
 
 ADMITTING OF SURGICAL TREATMENT. 
 
 BY ISAAC BAKER BROWN, 
 
 Surgeon Accoucheur to St. Mary's Hospital, &c. 
 
 WITH HANDSOME ILLUSTRATIONS. 
 
 In 07ie neat octavo volume, extra cloth, of two hundred and seventy-six 
 pages, $1 60. 
 
 During the appearance of this work in the "Medical News and Li- 
 brary" for 1855 and 1856, it commanded the warmest approbation of 
 the profession. To the practitioner the work possesses peculiar import- 
 ance as treating- fully and completely of a class of accidents and diseases 
 of frequent occurrence, which have hitherto received but little attention 
 from writers of systematic works. Occupying a middle ground be- 
 tween surgery and obstetrics, the authorities on each subject have well- 
 nigh abandoned them to the consideration of the other, and thus they 
 are nowhere to be found treated with the attention to which their import- 
 ance is entitled. The subjects considered in extenso are Ruptured Pe- 
 rineum—Prolapse of the Vagina — Prolapse of the Uterus — Vesico-Vagi- 
 nal Fistula — Recto- Vaginal Fistula — Lacerated Vagina — Polypus of the 
 Uterus — Stone in the Female Bladder — Vascular Tumor of the Meatus 
 Urinarius — Imperforate Hymen — Encysted Tumor of the Labia — Dis- 
 eases of the Rectum arising from the Uterus — Ovarian Dropsy. 
 
 Needle for Ruptured 
 Peri7ieum . 
 
 A PRACTICAL TREATISE ON THE DISEASES PECULIAR TO WOMEN. 
 
 Illustrated by Cases derived from Hospital and Private Practice. By Samuel Ashwell, M- D., 
 Obstetric Physician and Lecturer to Guy's Hospital, London. Third American, from the 
 Ihird and Revised London edition. In one octavo volume of 528 pages; extra cloth, $3. 
 
 The most useful practical work on the subject in the 
 English language. — Boston Med. and Surg. Journal. 
 
 The most able, and certainly the most standard and 
 practical, work on female diseases that we have yet 
 seen. — Medico-Chirurgical Review. 
 
 The young practitioner will find it invaluable, while 
 those who have had most experience will yet find 
 
 something to learn, and much to commend, in a book 
 which shows so much patient observation, practical 
 skill, and sound sense. — British and Foreign Med. Re- 
 view. 
 
 We commend it to our readers as the best practical 
 treatise on the subject which has yet appeared. — Lon- 
 d<m Lancet. 
 
52 
 
 BLANCHARD AND LEA'S 
 
 New and Enlarged Edition — (Preparing.) 
 
 Uterus and Lateral Ligaments. 
 
 A PKACTICAL TREATISE ON INFLAMMATION OF THE UTERUS, 
 
 ITS CERVIX AND APPENDAGES; 
 
 AND ON ITS CONNECTION WITH UTERINE DISEASE. 
 
 BY JAMES HENRY BENNET, M. D. 
 
 New and much enlarged Edition; preparing by the author for publication in 1859. 
 
 The best treatise of the kind in the English lan- 
 guage, and we know of none in the French or German 
 that are equally valuable. It certainly is no small 
 compliment to Dr. Bennet, that his treatise is pub- 
 lished in the latter countries, and that a fourth edition 
 has been called for and issued in this country. It 
 must be admitted that Dr. Bennet's writings have 
 
 served to mark a new era in the literature, if not in 
 the pathological doctrines of this department of Medi- 
 cine. In point of general accuracy and practical va- 
 lue, there certainly is no other treatise that equals 
 this. No physician's library can be complete without 
 the incomparably excellent work of Dr. Bennet. — 
 JV. Y. Journal of Medicine. 
 
 By the same Author, 
 
 A REVIEW OF THE PRESENT STATE OF UTERINE PATHOLOGY. One 
 
 small volume, octavo, flexible cloth, 50 cents. 
 
 A New Work on Leucorrhcea— (Lately Published.) 
 
 THE PATHOLOGY AND TREItMENT OF LEUCOKRH(EA. 
 
 W. TYLER SMITH, M.D., 
 
 Physician -Accoucheur to St. Mary's 
 Hospital, &c. 
 
 With handsome Illustrations. 
 
 In one beautifully printed 8vo. volume 
 o/200 pages; extra cloth, $1 50. 
 
 We decide this book to be one of the 
 most useful monographs which has ap- 
 peared in this country. What was be- 
 fore unutterable confusion in regard to 
 its subject has now the order, regularity, 
 and harmony of a most beautiful sci- 
 ence. Dr. Smith has placed the whole 
 profession directly, and mankind indi- 
 rectly, under abiding obligations. — 
 Nashville Journal of Medicine. 
 
 We hail the appearance of this prac- 
 tical and invaluable work, therefore, as 
 a real acquisition to our medical litera- 
 ture. — Medical Gazette. 
 
 Villi of Os Uteri, magnified 230 diameters. 
 
MEDICAL AND SCIENTIFIC PUBLICATIONS. 
 
 53 
 
 Now Complete— (October, 1858). 
 
 LECTURES ON THE DISEASES OF WOMEN. 
 
 BY CHARLES WEST, M.D., 
 
 Author of " Lectures on the Diseases of Children;" Aecoucheur to and Lecturer on Midwifery at St. Bartholo- 
 mew's Hospital; Physician to the Hospital for Sick Children, &c. 
 
 Now coinplete in one handsome octavo volume, extra cloth, of about 500 'pages ; $2 50. 
 
 Also, for sale separate. Part II., being pp. 309 to end, with Index, Title matter, &c. 8vo., cloth, 
 
 $1. 
 Part I. will no longer be sold separate. 
 
 The enviable reputation acquired for Dr. West by his former writings will be more than sus- 
 tained by the present volume. His large experience both in hospital and private practice, his 
 just and reasonable views on vexed questions, and his happy faculty of conveying information 
 in a clear and precise manner, give him great advantages as a teacher, and the unanimous ver- 
 dict of the profession has pronounced that he has made the best use of these advantages. The 
 first portion of these Lectures, as published in the "Medical News and Library" for 1856 
 and 1857, at once attracted the most favorable attention, and was regarded as one of the best 
 Works for both student and practitioner that had appeared on this interesting department of 
 medicine. That portion constituted a complete treatise on the Diseases of the Uterus. The 
 concluding part, now ready, treats in an equally thorough and satisfactory manner of the Ute- 
 rine Appendages, the Ovaries, Vagina, Bladder, and External Organs; and, taken toge- 
 ther, they form, in one neat volume, a clear and compendious text-book on the special di.seases 
 to which the female is liable. 
 
 |^° Copies of Part II., done up in paper covers, for mailing, will be sent, free of postage, to any 
 address within the United States on receipt of One Dollar in current funds or postage stamps. 
 Subscribers to the "Mb-dical News and Library" who received the lirst portion of this 
 work as published in 1856 and 1857, should lose no time in securing the completion. 
 A few notices of Part I. are added. 
 
 As a writer, Dr. West stands, in our opinion, second 
 only to Watson, the ''Maeaulay of Medicine;" he pos- 
 sesses that happy faculty of clothing instruction in 
 easy garments; combining pleasure with protit, he 
 leads his pupils, in spite of the ancient proverb, along 
 a royal road to learning. His work is one which will 
 not satisfy the extreme on either side, but it is one 
 that will please the great majority who are seeking 
 truth, and one that will convince the student that he 
 has committed himself to a candid, safe, and valuable 
 guide. We anticipate with pleasure the appearance 
 of the second part of the work, which, if it equals this 
 part, will complete one of our very best volumes upon 
 diseases of females. — N. A. Med.-Chirurg. Review, Ju- 
 ly, 1858. 
 
 We must now conclude this hastily written sketch 
 with the confident assurance to our readers that the 
 work will well repay perusal. The conscientious, 
 painstaking, practical physician is apparent on every 
 page. — New York Journal of Medicine, March, 185S. 
 
 We have to say of it, brieHy and decidedly, that it 
 is the best work on the subject in any language ; and 
 that it stamps Dr. West as the/aa7e princeps of British 
 obstetric authors. — Edinburgh Medical Journal. 
 
 We gladly recommend his Lectures as in the high- 
 est degree instructive to all who are interested in ob- 
 stetric practice. — London Lancet. 
 
 We know of no treatise of the kind so complete and 
 yet so compact. — Chicago Medical Journal, Jan. 1858. 
 
 A fairer, more honest, more earnest, and more reli- 
 able investigator of the many diseases of women and 
 children is not to be found in any country. — Southern 
 Medical and Surgical Journal, January, 1858. 
 
 Happy in his simplicity of manner and moderate 
 in his expression of opinion, the author is a sound 
 reasoner and a good practitioner, and his book is wor- 
 thy of the hand.some garb In which it has appeared 
 from the press of the Philadelphia publishers. — Vir- 
 ginia Med. Journal. 
 
 We must take leave of Dr. West's very useful work, 
 with our commendation of the clearness of its style, 
 and the industry and sobriety of judgment of which it 
 gives evidence. — London Med. Times and Gazette. 
 
 Sound judgment and good sense pervade every 
 chapter of the book. From its perusal we have de- 
 rived unmixed satisfaction. — Dublin Quarterly Journ. 
 
 Recently Issued. 
 
 AN ENQUIRY" INTO THE PATHOLOGICAL IMPORTANCE OF ULCERA- 
 TION OF THE OS UTERI. By Charles West, M.D., Author of "Lectures on the 
 Diseases of Women," &c. In one neat volume, small Svo., extra cloth, $1. 
 
 THE CAUSES AND TREATMENT OF ABORTION AND STERILITY; 
 
 Being the Result of an Extended Practical Inquiry into the Physiological and Morbid Conditions 
 of the Uterus. By James Whitehead, F. R. C, S., &c. Second American Edition. In one 
 octavo volume, extra cloth, of 368 pages, f 1 75. 
 
54 
 
 BLANCHARD AND LEA'S 
 
 Just Issued. 
 AN EXPOSITION OF THE 
 
 SIGNS AND SYMPTOMS OF PREGNANCY. 
 
 WITH SOME OTHER PAPERS ON SUBJECTS CONNECTED WITH MIDWIFERY. 
 BY W. F. MONTGOMERY, M. D., M. R. I. A., 
 
 Professor of Midwifery in the King and Queen's College of Physicians in Ireland, &c. 
 
 FROM THE SECOND AND ENLARGED ENGLISH EDITION. 
 
 Witli T-tvo Exquisite Colored Plates and nnmerons 'Wood-cuts* 
 
 In one very handsome octavo volume of about &(iO pages j extra cloth, S3 75. 
 
 Cervix Uteri in the Seventh Month. 
 
 This work, which has attained the position of a medical classic, 
 has received from the author the most careful and thorough revi- 
 sion To use his own words — " The present Treatise, though only 
 another edition of a work already published, may be, I think, with 
 trul h regarded as almost a new book ; every sentence of the former 
 having been carefully revised, and the quantity of new matter now 
 added being more than equal in amount to the entire contents of the 
 former edition." Translated into various languages, and univer- 
 sally regarded as the highest authority on the interesting questions 
 discussed, its high character will be fully maintained, the author 
 having exhausted the subject in all its bearings, examining it with 
 all the aids of the most recent investigations, assisted by his own 
 long and enlarged experience. 
 
 The title scarcely does justice to the scope of the work. With 
 the exception of the procedures of operative midwifery, almost 
 everything connected wlh pregnancj' and delivery is brought un- 
 der Consideration, and there are few physicians who will not find 
 in its pages much that will prove of value in the every-day practice 
 of their profession. Besides the full consideration of the principal 
 subject of the work, there are special chapters on the Period of 
 Human Gestation, the Signs of Deliv-ery, and Spontaneous Ampu- 
 tation and other Accidents to the Fcetus in Utero, the latter illus- 
 trated with numerous figures. 
 
 In every respect, the mechanical execution of the work will be 
 found worthy of its distinguished reputation. 
 
 Spontaneous Amputation in Clero. 
 
MEDICAL AND SCIENTIFIC P LT BLIC A TIONS. 
 
 55 
 
 New and Improved Edition— (Lately Issued.) 
 
 In one large 
 
 and very handsome 
 
 imperial octavo volume 
 
 of six hundred and 
 
 fifty pages, 
 
 with sixty-four plates, 
 
 and numerous 
 wood-cuts in the text, 
 
 containing in all 
 nearly 200 large and 
 beautiful figures, 
 strongly bound in 
 leather, with raised 
 bands; price $5. 
 
 Tivins in Utero. 
 
 THE PRINCIPLES AND PRACTICE OF 
 
 OBSTETRIC MEDICINE AND SURGERY, 
 
 IN REFERENCE TO THE PROCESS OF PARTURITION. 
 BY FRANCIS H. RAMSBOTHAM, M. D. 
 
 A NEW AND ENLARGED EDITION, THOROUGHLY REVISED BY THE AUTHOR. 
 
 With Additions by W. V. KEATING, M. U. 
 
 In calling the attention of the profession to the new^ edition of this standard work, the pub- 
 lishers would remark that no efforts have been spared to secure for it a continuance and exten- 
 sion of the remarkable favor with which it has been received. The last London issue, which 
 was considerably enlarged, has received a further revision from the author, especially for this 
 country. Its passage through the press here has been supervised by Dr. Keating, who has made 
 numerous additions with a view of presenting more fully whatever was necessary to adapt it 
 thoroughly to American modes of practice, and in its mechanical execution, a similiar superio- 
 rity over former editions will be found. 
 
 From Prof. Hodge, of the University of Pennsylvania. 
 To the American public, it is most Taluable. from 
 its intrinsic undoubted excellence, and as being the 
 best authorized exponent of British Midwifery. Its 
 circulation will, I trust, be extensive throughout our 
 country. 
 
 But once in a long time some brilliant genius rears 
 his head above the horizon of science, and illuminates 
 and purities every department that he investigates; 
 and his works become types, by which innumerable 
 imitators model their feeble productions. Such a genius 
 ■we find in the younger Ramsbotham, and such a type 
 •we find in the work now before us. The binding, pa- 
 per, type, the engravings and wood-cuts are all so ex- 
 cellent as to make this hook one of the finest specimens 
 of the art of printing that have given such a world- 
 
 wide reputation to its enterprising and liberal publish- 
 ers. We welcome Kamsbotham's Principles and Prac- 
 tice of Obstetric Medicine and Surgery to our library, 
 and confidently recommend it to our readers, with the 
 assurance that it will not disappoint their most san- 
 guine expectations. — Western Lancet. 
 
 The publishers have shown their appreciation of the 
 merits of this work and secured its success by the truly 
 elegant style in which they have brought it out, ex- 
 celling themselves in its production, especially in its 
 plates. It is dedicated to Prof. Meigs, and has the em- 
 phatic endorsement of Prof Hodge, as the best expo- 
 nent of British Midwifery. We know of no text-book 
 which deserves in all respects to he more highly re- 
 commended to students, and we could wish to see it 
 in the hands of every practitioner, for they will find it 
 invaluable for reference. — Med. Gazette. 
 
56 
 
 BLANCHARD AND LEA'S 
 
 New and Improved Edition — (Just Issued.) 
 
 OBSTETRICS; 
 
 THE SCIENCE A-ND THE J^TiT. 
 
 BY CHAKLES D. MEIGS, M. D., 
 
 Professor of Midwifery and Diseases of Women and Children in Jefferson Medical College, of Philadelphia. 
 
 THIRD EDITION, REVISED. 
 
 With one hundred and twenty-nine Illuslratious. 
 
 In one large and handsome octavo volume, of over 150 pages, leather, $3 75. 
 
 Section of Pelvic Viscera. 
 
 The rapid demand for another edition of this work is a sufficient expression of the favorable 
 verdict of the profession. In thus preparing it a third time for the press, the author has endea- 
 vored to render it in every respect worthy of the favor which it has received. To accomplish 
 this he has thoroughly revised it in every part. Some portions have been rewritten, others 
 added, new illustrations have been in many instances subf^tituted for such as were not deemed 
 satisfactory, while, by an alteration in the typographical arrangement, the size of the work has 
 not been increased, and the price remains unaltered. In its present improved form, it is, there- 
 fore, hoped that the work will contmue to meet the wants of the American profession as a 
 sound, practical, and comprehensive System of Midwifery. 
 
MEDICAL AND SCIENTIFIC PUBLICATIONS. 
 
 57 
 
 A NEW OBSTETEICAL TEXT-BOOK.— (Just Issued, 1858.) 
 
 THE PRINCIPLES AND PRACTICE OF OBSTETRICS; 
 
 INCLUDING THE TREATMENT OF CHRONIC INFLAMMATION OF THE UTERUS. CON- 
 SIDERED AS A FREQUENT CAUSE OF ABORTION. 
 
 By henry miller, M.D., 
 
 Professor of Obstetric Medicine in the Medical Department of the University of Louisville, &c. 
 
 WITH ILLUSTRATIONS ON WOOD. 
 
 In one handsome octavo volume q/" 624 pages; leather, price $3 75. 
 
 The reputation 
 of Dr. Miller a.< an 
 obstetrician is too 
 widely spread to 
 require the pub- 
 lishers to ask the 
 attention of the 
 profession special- 
 ly to a volume 
 containing the ex- 
 perience of his 
 long and extensive 
 practice. The ve- 
 ry favorable recep- 
 tion accorded to his 
 "Treatise on Hu- 
 man Parturition," 
 issued some years 
 since, is an earnest 
 that the present 
 work will fulfil the 
 author's intention 
 of providing with- 
 in a moderate com- 
 pass a complete 
 and trustworthy 
 text-book for the 
 student, and book 
 of reference for 
 the practitioner. 
 Based to a certain 
 extent upon the 
 former work, but 
 enlarged to more 
 than double its 
 size, and almost 
 wholly rewritten, 
 it presents, besides 
 the matured expe- 
 rience of the au- 
 thor, the most re- 
 cent views and investigations of modern obstetric writers, such as Dubois, Cazeaux, Simpson, 
 Tyler Smith, &c., thus embodying the results not only of the American, but also of the Paris, 
 the London, and the Edinburgh obstetric schools. The author's position for so many years as 
 a teacher of his favorite branch, has given him a familiarity with the wants of students and a 
 facility of conveying instruction, which cannot fail to render the volume eminently adapted to 
 its purposes. 
 
 Internal face of Uterus, after delivery. 
 
 To fiillow the many tempting leads offered in this 
 work would be an impossibility, with the limits here 
 assigned, and the cursory character of the notice can be 
 the more readily reconciled to the reviewer's mind, as 
 he can heartily recommend the book, not in the hack- 
 neyed phrase as one ''without which no physician's 
 library can be considered complete," but as instruct- 
 ive and sugsrestive to the student, and refreshing to 
 the obstetrician, from its manliness and the straight- 
 forward way in which all questions interesting to the 
 author are met. — N. T. Journ. of Med., Sept. 1S58. 
 
 In conclusion, we can only express our regret that 
 we cannot do full justice to this e.xcellent book, by 
 presenting larger extracts, in an extended review. 
 We can only now say that, we have derived much 
 pleasure anil benefit from its perusal, and that we 
 cordially recommend it to the profession, both to prac- 
 titioners and to pupils. — Southern Medical and Surgi- 
 cal Journal, Aug. 1858. 
 
 A work which is well deserving of being ranked 
 among the very best treatises on this important branch 
 
 of medicine. As an American book, we commend it 
 to the special favor of our readers — not so much, how- 
 ever, on account of its domestic origin as for its real 
 merit. — St. Louis Med and Surg. Journ., March, 1858. 
 
 Destined to assume a high and permanent rank 
 among the standard American treatises on the theory 
 and practice of midwifery. It is not only generally 
 full, correct, clear, and distinct in its teachings, but 
 it presents a manly vigor and directness in the hand- 
 ling of all the questions embraced within its general 
 subject, that cannot fail to impart themselves, in some 
 extent, at least, to its readers; inducing them, in their 
 turn, to examine, think, and decide for themselves.— 
 N. A. Medico-Chirurgical Review, May, 1858. 
 
 On account of its sound practical value, great clear- 
 ness, and, in most portions, conciseness, we do not 
 hesitate to commend it both to the young student and 
 to the old practitioner, and we believe there are but 
 few even of the latter class who will not acknowledge 
 that tbey have been much instructed as well as en- 
 tertained by its perusal. — Charleston Med. Jownal and 
 Review, May, 1858. 
 
58 
 
 BLANCHARD AND LEA'S 
 
 THE STUDENT'S TEXT-BOOK OF MIDWIFERY. 
 
 In one 
 
 very handsome 
 
 octavo volume 
 
 of over 
 
 five hundred pages, 
 
 with 
 
 one hundred and 
 
 thirty-nine 
 
 beautiful wood engravings; 
 
 leather, price $3. 
 
 Application of the Long Forceps. 
 
 ON THE THEORY AND PRACTICE OF MIDWIFERY. 
 
 BY FLEETWOOD CHURCHILL, M. D., M. R. I. A., 
 
 Author of "A Treatise on Diseases of Females," "Infants and Children," &c. 
 
 A NEW AMERICAN, FROM A LATE AND IMPROVED ENGLISH EDITION. 
 
 With Notes and Additions by D. F. CONDIE, M.D. 
 
 To bestow praise on a book that has received such 
 marked approbation would be superfluous. We need 
 only say, therefore, that if the first edition was thought 
 worthy of a favorable reception by the medical public, 
 we can confidently affirm that this will be found much 
 more so. The lecturer, the practitioner, and the stu- 
 dent, may all have recourse to its pages, and derive 
 from their perusal much interest and instruction in 
 everything relating to theoretical and practical mid- 
 wifery. — Dublin Quartei-ly Journal of Medical Science.. 
 
 A work of very great merit, and such as we can 
 confidently recommend to the study of every obstetric 
 practitioner. — London Medical Gazette.. 
 
 This is certainly the most perfect system extant. It 
 is the best adapted for the purposes of a text-book, and 
 that which he whose necessities confine him to one 
 book, should select in preference to all others. — South- 
 ern Medical and Surgical Journal. 
 
 The most popular work on midwifery ever issued 
 from the American 'press.— Charleston Med. Journal. 
 
 Were we reduced to the necessity of having but one 
 work on midwifery, and permitted to choose, we would 
 unhesitatingly take Churchill. — Western Med. and 
 Surg. Journal. 
 
 No work holds a higher position, or is more deserving 
 of being placed in the hands of the tyro, the advanced 
 student, or the practitioner. — Medical Examiner. 
 
 Previous editions, under the editorial supervision of 
 Prof. R. M. Huston, have been received with marked 
 favor, and they deserved it; but this, reprinted from 
 a very late Dublin edition, carefully revised and 
 brought up by the author to the present time, does 
 present an unusually accurate and able exposition of 
 every important particular embraced in the depart- 
 ment of midwifery. * * The clearness, directness, and 
 precision of its teachings, together with the great 
 amount of statistical research which its text exhibits, 
 have served to place it already in the foremost rank of 
 works in this department of remedial science. — N. O. 
 Medical and Surgical Journal. 
 
 In our opinion, it forms one of the best if not the 
 very best text-book and epitome of obstetric science 
 which we at present possess in the English language. 
 — Monthly Journal of Medical Science. 
 
 Few treatises will be found better adapted as a text- 
 book for the student, or as a manual for the frequent 
 consultation of the young practitioner. — American 
 Medical Journal. 
 
 DEWEES'S COMPREHENSIVE SYSTEM OF MIDWIFERY. Illustrated 
 
 by occasional oases and many engravings. Twelfth edition, with the author's last improve- 
 ments and corrections. In one octavo volume, extra cloth, of 600 pages, $3 20. 
 
 A SYSTEM OF MIDWIFERY. By Edward Rigby, M.D., Physician to 
 
 the General Lying-in Hospital, &c. Second American edition, with Notes and additional 
 Illustrations. In one octavo volume of 422 pages ; extra cloth, $2 50. 
 
 ON PARTURITION, AND THE PRINCIPLES AND PRACTICE OF 
 
 OBSTETRICS. By W. Tyler Smith, M. D., Physician-Accoucheur to St. Mary's Hospi- 
 tal, &c. In one royal 12mo. volume of 400 pages ; extra cluth, f 1 25. 
 
MEDICAL AND SCIENTIFIC PUBLICATIONS. 
 
 59 
 
 SURGICAL ANATOMY. 
 
 BY JOSEPH MACLISE, Surgeon. 
 
 FORMING ONE VOLUME, VERY LARGE IJIPERIAL QUARTO. 
 WITU 
 
 ^ktg-Jigljt Inrgc anb ^plcnbib ^lat^s brafon in tljt htst stjrlc, anb bcautifwlljr toloxzh. 
 
 Containing one hundred and ninety Figures, many of them the size of life. 
 
 TOGETHER WITH COPIOUS AND EXPLANATORY LETTER- PRESS. 
 
 Strongly and handsoTtiely hound in extra cloth, being one of the clieapest and best executed 
 Surgical works as yet issued in this country, $11 00; also, in leather, $12 00. 
 
 *^* The size of this work prevents its transmission by mail as a vi^hole, but copies are furnished 
 for that purpose, in live parts, done up in stout wrappers ; price $9 00. 
 
 This great work being now concluded, the publishers confidently present it to the attention 
 of the profession as worthy in every respect of their approbation and patronage. No complete 
 work of the kind has yet been published in the English language, and it therefore will supply 
 a want long felt in this country of an accurate and comprehensive Atlas of Surgical Anatomy 
 to which the student and practitioner can at all times refer, to ascertain the exact relative posi- 
 tion of the various portions of the human frame towards each other and to the surface, as well 
 as their abnormal deviations. The importance of such a work to the student in the absence oi 
 anatomical material, and to the practitioner when about attempting an operation, is evident ; 
 while the price of the book, notwithstanding the large size, beauty, and finish of tlie very nu- 
 merous illustrations, is so low as to place it within the reach of every member of the profession. 
 The publishers therefore confidently anticipate a very extended circulation for this magnificent 
 work. 
 
 One of the greatest artistic triumphs of the age 
 in Surgical Anatomy. — British American Medical 
 Journal. 
 
 Too much cannot be said in its praise; indeed, we 
 have not language to do it justice. — Ohio Medical and 
 Surgical Journal. 
 
 The most admirable surgical atlas we have seen. 
 To the practitioner deprived of demonstrative dissec- 
 tions upon the human subject, it is an invaluable 
 companion. — If. J. Medical Jieporter. 
 
 The most accurately engraved and beautifully 
 colored plates we have ever seen in an American 
 book — one of the best and cheapest surgical works 
 ever published. — Buffalo Medical Journal. 
 
 It is very rare that so elegantly printed, so well il- 
 lustrated, and so useful a work, is offered at so mode- 
 rate a price. — Charleston Medical Journal. 
 
 Its plates can boast a superiority which places them 
 almost beyond the reach of competition. — Medical 
 Examiner. 
 
 Every practitioner, we think, should have a work 
 of this kind within reach. — Southern Medical and 
 Surgical Journal. 
 
 No such lithographic illustrations of surgical re- 
 gions have hitherto, we think, been given. — Boston 
 Medical and Surgical Journal. 
 
 As a surgical anatomist, Mr. Maclise has probably 
 no superior. — British and Foreign Medico-Ohirurgical 
 Jteview. 
 
 Of great value to the student engaged in dissecting, 
 and to the surgeon at a distance from the means of 
 keeping up his anatomical knowledge. — Medical Times. 
 
 The mechanical execution cannot be excelled. — 
 Transylvania Medical Journal. 
 
 A work which has no parallel in point of accuracy 
 and cheapness in the English language. — N. Y. Journal 
 of Medicine. 
 
 No practitioner whose means will admit should fail 
 to possess it. — Banking's Abstract. 
 
 Country practitioners will find these plates of im- 
 mense value. — JV. Y. Medical Gazette. 
 
 To all engaged in the study or practice of their pro- 
 fession, such a work is almost indispensable. — Dublin 
 Quarterly Medical Journal. 
 
 We are extremely gratified to announce to the pro- 
 fession the completion of this truly magnificent work, 
 which, as a whole, certainly stands unrivalled, both 
 for accuracy of drawing, beauty of coloring, and all 
 the requisite explanations of the subject in hand. To 
 the publishers, the profession in America is deeply 
 indebted for placing such a valuable, such a useful 
 work, at its disposal, and at such a moderate price. It 
 is one of the most finished and complete pictures of 
 Surgical Anatomy ever off'ered to the profession of 
 America. With these plates before them, the student 
 and practitioner can never be at a loss, under the 
 most desperate circumstances. We do not intend 
 these for commonplace compliments. We are sincere ; 
 because we know the work will be found invaluable 
 to the young, no less than the old, surgeon. — The New 
 Orleans Medical and Surgical Journal. 
 
 This is by far the ablest work on Surgical Anatomy 
 that has come under our observation. We know of 
 no other work that would justify a student, in any 
 degree, for neglect of actual dissection. A careful 
 study of these plates, and of the commentaries on 
 them, would almost make an anatomist of a diligent 
 student. And to one who has studied anatomy by 
 dissection, this work is invaluable as a perpetual re- 
 membrancer, in matters of knowledge that may slip 
 from the memory. The practitioner can scarcely con- 
 sider himself equipped for the duties of his profession 
 without such a work as this — and this has no rival — 
 in his library. In those sudden emergencies that so 
 often arise, and which require the instantaneous com- 
 mand of minute anatomical knowledge, a work of this 
 kind keeps the details of the dissecting-room perpetu- 
 ally fresh in the memory. We repeat that no medical 
 library, however large, can be complete without Ma- 
 clise's Surgical Anatomy. The American edition is 
 well entitled to the confidence of the profession, and 
 should command, among them, an extensive sale. 
 The investment of the amount of the cost of this 
 work will prove to be a very profitable one, and if 
 practitioners would qualify themselves thoroughly 
 with such important knowledge as is contained in 
 works of this kind, there would be fewer of them sigh- 
 ing for employment. — The Western Journal of Medicine 
 and Surgery. 
 
 1^° The very low price at which this work is furnished, and the beauty of its execution, 
 require an extended sale to compensate the publishers for the heavy expenses incurred. 
 
60 
 
 BLANCHARD AND LEA'S 
 
 GROSS' SURGERY— (To be ready in July, 1859.) 
 
 Dislocaiion of the Knee. 
 
 A SYSTEM OF SURGERY; 
 
 Diagnostic, Pathological, Therapeutic, and Operative. 
 
 BY SAMTJEL D. GROSS, M.D., 
 
 Professor of Surgery in the Jefferson Medical College of Philadelphia, &c. 
 
 WITH OVER SEVEN HUNDRED ILLUSTRATIONS: 
 
 A LARGE NUMBER OF WHICH ARE FROM ORIGINAL DRAWINGS. 
 
 Li tvjo very large octavo vohtmes, of more than 2000 closely printed 'pages., strongly bound in 
 
 leather., vnth raised hands. 
 
 The want has long existed of a complete 
 American System of Surgery — a work which 
 should present the experience of practitioners 
 on Ihis side of the Atlantic as well as of those 
 ^ of Europe in all the various departments of 
 / surg-ical science. To accomplish this has been 
 the author's aim in the present work. The 
 thorough execution of his plan has required a 
 delay far beyond what was originally contem- 
 plated, but the advantages resulting from the 
 increased time and labor thus bestowed upon 
 it will be evident from the completeness with 
 which he has thus been enabled to treat all 
 the various divisions of the subject. He has 
 thus hoped to render it a work from which 
 the student can derive the elementary prin- 
 ciples of the science, while the mature prac- 
 titioner can likewise feel assured that in the 
 emergencies of his profession, the immense 
 amount of practical matter and important de- 
 tails embodied in its pages may furnisti him 
 whatever assistance may be required at the 
 moment. With this view the work has not 
 been confined to the usual topics treated in 
 the ordinary text-books, but the subsidiary branches of Surgery have received the attention to 
 which their importance entitles them. 'Thus, Ophthalmic and Aural Surgery, the Surgical 
 Diseases of Females, Fractures and Dislocations, xMinor Surgery, Dentistry, &:c. &rc., have been 
 developed with a fulness of which the object has been to furnish all that the wants of the prac- 
 tising surgeon could reasonably require. Such being the design of the work, the student who 
 procures it can feel that he does not merely possess a guide (or his preliminary studies, but a 
 copious book of reference, to be preserved for consultation during his whole professional career. 
 In view of the magnitude and importance of the work, the publisters have spared neither 
 labor nor expense to "render its external appearance in every respect unexceptionable, and to 
 carry out fully the designs of the author. The series of illustrations is fuller and more complete 
 than has hitherto been attempted in any work of the kind, and while wood-cuts have been un- 
 sparingly selected from every authoritative and accessible source, a very large nurnber of ori- 
 ginal drawings have been prepared, where the material already existing was unsatisfactory or 
 insufficient. Printed in the handsomest manner, with new and clear type, on fine paper, these 
 volumes are therefore offered to the profession with the hope that they will fully meet the views 
 of the most exacting and fastidious ; and that no practitioner, however well supplied his library 
 may be, will consider it complete without them. 
 
 Ele'pho. nt iasts. 
 
MEDICAL ANDSCIENTIFIC PUBLICATIONS. 
 
 61 
 
 New and enlarged edition — Now Ready (1859). 
 
 THE SCIENCE AND ART OF SURGERY. 
 
 tontist m\ .Surgical Injuries, §m$ts, auij 6pi''ations. 
 
 BY JOHN ERICHSEN, 
 
 Professor of Surgery in University College, London, &c. 
 
 A New and improved American, from the Second enlarged and carefully revised English 
 
 edition. 
 
 ILLUSTRATED BY OVER FO0R HUNDRED ENGRAVINGS ON 'WOOD, MANY OF WHICH ARE FROM 
 
 NEW SUBJECTS. 
 
 In one very large and handsome octavo volume, of 1000 closely pri')i?ecZ lyages, strongly hound in 
 leather, with raised bands ; price $4 50. 
 
 Lateral Flap Operation of the Thigh. 
 
 The author has subjected this work to a most thorough revision, and every portion will be 
 found to bear the marks of his desire to render it an exponent of the most advanced condition 
 of surgical science, as is shown by the very considerable 
 increase in its s-ize, and in the number of illustrations. 
 The publishers therefore trust that it will be found to 
 merit a continuance of the very remarkable tavor with 
 which it has been received. 
 
 The present edition has been much extended, many of the 
 chapters entirely rewritten, and upwards of 160 new illustrations 
 liave been introduced. Great attention has been paid to all the 
 modern improTements in surgery, especially to the subject of 
 resection of joints, which is most fully considered and illustrated. 
 The additions to the work are almost exclusively of a practical 
 character. — London Lancet, Oct. 17, 1S57. 
 
 It requires no small power of condensation, no slight tact and 
 judgment, to prepare a work within a moderate compass on so 
 wide a subject as the science and art of Surgery, which shall 
 descend with sufficient minuteness into practical details to be- 
 come useful at the bedside, and at the same time shall expound 
 those principles which are to guide the student in his studies of 
 surgical science. Mr Erichsen's task was a most difficult one, 
 and he has accomplished it in a manner which entitles his work 
 to a place beside AVatson's Lectures on the sister science It 
 would not be easy to award any surgical work a higher meed of 
 praise. — London Med. Times and Gazette, Oct. 31, 1857. 
 
 It is, in our humble judgment, decidedly the best book of the 
 kind in the English language. Strange that just such books are 
 not oftener produced by public teachers of surgery in this coun- 
 try and Great Britain. Indeed, it is a matter of great astonish- 
 ment, but no less true than astonishing, that of the many works 
 on surgery republished in this country within the last fifteen or 
 twenty years as text^ books for medical students, this is the only 
 one that even approximates to the fulfilment of the peculiar 
 ■wants of young men just entering upon the study of this branch 
 of the profession. — Western Journ. of Med. and Surgery. 
 
 Embracing, as will be perceived, the whole surgical domain, 
 and each division of itself almost complete and perfect, each 
 chapter full and explicit, each subject faithfully exhibited, we 
 can only express our estimate of it in the aggregate. AVe con- 
 sider it an excellent contribution to surgery, as probably the 
 best single volume now extant on the subject, and with great 
 pleasure we add it to our text-books. — Nashville Journ. of Med. 
 and Surgery. 
 
 Starched Bandage Apparatus for 
 Fractured Leg. 
 
62 
 
 BLAN CHARD A^^D LEA'S 
 
 New and Improved Edition — (Just Issued.] 
 
 Osleo sarcoma of Femur. 
 
 In one 
 
 large and 
 
 very handsome 
 
 octavo 
 
 volume, 
 
 of 
 
 700 pages, 
 
 vs'ith I 
 
 240 exquisite 
 
 engraving's 
 
 on 
 
 wood. 
 
 Bound ia 
 
 leather, 
 
 83 75. 
 
 THE 
 
 Abscess Viceralin^ into Carotid. 
 
 PRINCIPLES OF SURGERY. 
 
 BY JAMES MILLER, F. K. S. E., 
 
 Professor of Surgery in the Tniversity of Edinburgh, &c. 
 
 <f onrl^ g^meritan, from tbe C^irb anb ^ebiscb English (fintion. 
 
 The extended reputation enjoyed by this 
 work will be fully maintained by the present 
 edition. Thoroughly revised by the author, it 
 will be found a clear and compendious exposi- 
 tion of surgical science ia its most advanced 
 condition. 
 
 In connection with the recently issued third 
 edition of the author's "Practice of Surgery," 
 it forms a very complete system of Surgery in 
 all its branches. 
 
 Miller's Principles of Surgery has become a favorite 
 standard with surgeons wherever the English language 
 is spoken, and, together with Miller's Practice of .Sur- 
 gery, constitute a surgical library for all practical 
 purposes. — Nashville JournoX of Merli/yine, Sept. 1856. 
 
 The medical student who does not intend to prac- 
 tise operative surgery, nevertheless, will find Prof. 
 Millei^s Principles of Surgery one of the best books as 
 a safe guide in the practice of physic, not to say Sur- 
 gery. This fourth edition of Prof. Miller's Principles 
 of Surgery, now diligently revised, greatly enlarged, 
 abundantly illustrated, enriched with recent facts, 
 and reasoned out of the authors more matured and 
 enlarged experiences, must prove acceptable and very 
 necessary to both physicians and surgeons desirous of 
 keeping pace with the progress of medical knowledge. 
 — N. 0. Med. and Surg. Journal, May, 1S56. 
 
 On these accounts, especially, apart from the well- 1 
 known elegance and clearness of language, as well as 
 comprehensive range of topics and elevated scientific 
 tone of Prof Miller's treatise, we are glad to believe 
 that its high position as one of the acknowledged ex- 
 emplars of the Princijjles of Surgery- perhaps the 
 best of its class — ;,) abundantly maintained. We 
 heartily commend it to the atteotion of pupils and 
 
 BMMi^^mi,.^. 
 
 
 Simple and Compound Cancer Cells. 
 
 practitioners as a valuable elementary preceptor. 
 They may safely resort to it, and, within the limits of 
 a text-book, depend upon it as a reliable monitor and 
 guide in their earlier studies; while they will be apt 
 to find it, along with works of greater compass and 
 pretension, no mean instructor in any stage of a pro- 
 fessional career. — American Journal Med. Sciences. 
 
MEDICAL AND SCIENTIFIC PUBLICATIONS. 
 
 63 
 
 THE PRACTICE OF SURGERY. 
 
 BY JAMES MILLER, F. K. S. E., 
 
 Professor of Surgery in the University of Edinburgh. 
 A NEW AND REVISED AMERICAN, FROM THE LAST ENGLISH EDITION. 
 
 5(iUtlj obex time l^unirrcit bjcatttxftil |llti stations an SSoob. 
 
 In one very large and handsome octavo vohnrie, of over seven Inindred pages ; leather, $3 75. 
 To match the "Principles of Surgery." 
 
 Ligatures of the Posterior Tibial. 
 
 Pulypt of the Face. 
 
 By the almost unanimous voice of the profession, 
 his works, both on the principles and practice of sur- 
 gery, have been assigned the highest rank. If ■we 
 were limited to but one work on Surgery, that one 
 should be Millers, as we regard it superior to all 
 others. — St. Loiiii Med. and Surg. Journal. 
 
 The author, distinguished alike as a practitioner 
 and writer, has in this and his'' Principles," presented 
 to the profession one of the most complete and reliable 
 systems of Surgery extant. His style of writing is 
 original, impressive, and engaging, energetic, concise, 
 and lucid. Few have the faculty of condensing so 
 much in small space, and at the same time so persist- 
 ently holding the attention; indeed, he appears to 
 make the very process of condensation a means of 
 producing attractions. Whether as a test-book for 
 students or a book of reference for practitioners, it can- 
 not be too strongly recommended. — Southern Journal 
 of Medical and Physical Science. 
 
 No encomium of ours could add to the popularity of 
 Miller's Surgery. Its reputation in this country is 
 unsurpassed by that of any other work, and, when 
 taken in connection with the author's Principles of 
 Surgery, constitutes a whole, without reference to 
 which no conscientious surgeon would be willing to 
 practise his art. — Southern Med. and Surg. Journal. 
 
 It is seldom that two volumes have ever made so 
 profound an impression in so short a time as the 
 "Principles" and the " Practice" of Surgery, by Mr. 
 Miller — or so richly merited the reputation they have 
 acquired. The author is an eminently sensible, prac- 
 tical, and well-informed man, who knows exactly what 
 he is talking about and exactly how to talk it. — Ken- 
 tucky Medical Recorder. 
 
 The two volumes together form a complete expose 
 of the-present state of Surgery, and they ought to be 
 on the shelves of every surgeon. — N. J. Medical Re- 
 porter. 
 
64 
 
 BLANCHARD AND LEA'S 
 
 THE STUDENT'S TEXT-BOOK OF SURGERY. 
 
 With 
 
 one hundred and 
 
 ninety-three 
 
 beautiful illustrations 
 
 on wood; 
 
 bound in leather; 
 
 price $3. 
 
 In one 
 
 very handsome 
 
 octavo volume of 
 
 nearly six hundred 
 
 pages. 
 
 Syphilitic Caries of Skull. 
 
 THE PPiHCIPLES AND PEACTICE OF lODEPJ SURGERY. 
 
 BY ROBERT DRUTTT, 
 
 Fellow of the Royal College of Surgeons. 
 
 ■ '^ mb '^mtxkm, from a Iat« anb intprobjir IFonifon; ©bition. 
 Edited by F. W. SARGENT, M.D., 
 
 Author of " Minor Surgery," &c. 
 
 The author has evidently ransacked every standard 
 treatise of ancient and modern times, and all that is 
 really practically useful at the bedside will be found 
 in a form at once clear, dislinct, and interesting. — 
 Edinh. Monthly Med. Journal. 
 
 Bandage for Fractured Jaw 
 
 Druitt's work, condensed, systematic, lucid, and 
 practical as it is, beyond most works on Surgery ac- 
 cessible to the American student, has had much cur- 
 rency in this country, and under its present auspices 
 promises to rise to yet higher favor. — The Western 
 Journal of Medicine and Surgery. 
 
 The most accurate and ample r(5sume of the present 
 state of Sursery that we are acquainted with. — Dub- 
 lin Medical Journal. 
 
 A*hetter book on the principles and practice of Sur- 
 gery as now understood in England and America, has 
 not been given to the profession. — Boston Medical and 
 Surgical Journal. 
 
 An unsurpassable compendium, not only of Surgi- 
 cal, but of Medical Practice. — London Medical Gazette. 
 
 No work, in our opinion, equals it in presenting so 
 much valuable surgical matter in so small a compass. 
 — St. Louis Medical and Surgical Journal. 
 
 This work merits our warmest commendations, and 
 we strongly recommend it to young surgeons as an 
 admirable digest of the principles and practice of mo 
 dern Surgery.— J/«ZicaZ Gazette. 
 
 It may be said with truth that the work of Mr. Dru- 
 itt affords a complete, though brief and condensed 
 view of the entire tield of modern surgery. Vi'e know 
 of no work on the same subject having the appearance 
 of a manual, which includes so many topics of interest 
 to the surgeon; and the terse manner in which each 
 has been treated evinces a most enviable quality of 
 mind on the part of the author, who seems to have an 
 innate power of searching out and grasping the leading 
 facts and features of the most elaborate productions of 
 the pen. It is a useful handbook for the practitioner, 
 and we should deem a teacher of surgery unpardon- 
 able who did not recommend it to his pupils. In our 
 own opinion, it is admirably adapted to the wants of 
 the student. — Provincial Med. and Surgical Journal. 
 
MEDICAL AND SCIENTIFIC PUBLICATIONS. 
 
 65 
 
 THE PRINCIPLES AND PRACTICE OF SURGERY. 
 
 BY WILLIAM PIRRIE, F. R. S. E., 
 
 Regius Professor of Surgery in the University of Aberdeen, Ac. 
 
 Edited, with Additions, by JOHN NEILL, M. D., 
 
 Surgeon to the Pennsylvania Hospital, Professor of Surgery in the Penna. Medical College, &c. 
 
 In one large and handsome octavo volume of nearly 800 j)nges, leather, with three hundred and six- 
 ,. teen beautiful illustrations on wood ; price $3 75. 
 
 However well it 
 may be adapted for 
 a text-book (and in 
 this respect it may 
 compete with the 
 best of them), of 
 this much our read- 
 ing has convinced 
 us, that, as a sys- 
 tematic treatise, it 
 is carefully and ably 
 written, and can 
 hardly fail to com- 
 mand a prominent 
 position in the li- 
 brary of practition- 
 ers ; though not 
 complete in the full- 
 est sense of the 
 word, it neverthe- 
 less furnishes the 
 student and practi- 
 tioner with as con- 
 cise and chaste a 
 work as exists in 
 our language. The 
 additions to the vo- 
 lume by Dr. Neill, 
 are judicious; and 
 while they render 
 it more complete, 
 greatly enhance its 
 practical value, as a 
 work for practition- 
 ers and students. — 
 N. Y. Jour, of Med. 
 
 Our impression is 
 that, as a manual 
 for students, Pir- 
 rie's is the best 
 work extant.— West- 
 
 Lateral Operation of Lithotomy. 'Zr^^^; "'"^ '^"'•^• 
 
 c;,Y^ \^°^- °l^° °*^®'" ^"'gi^al work of a reasonable I We can pronounce it to be one of the best treatises 
 size, wherein there is so much theory and practice, or | on surgery in the English language. We very strono^lv 
 where .subjects are more soundly or clearly taught- I recommend this excellent work^ both to the practi- 
 1 ne stetlioscope. ( tioner and student.— Cajioda Medical Journal. 
 
 OPERATIVE SURGERY. 
 
 BY FREDERICK C. SKEY, F.R.S. 
 
 With about 100 Engravings on Wood. 
 
 In one handsome octavo volume of over 6b0 pages; ex- 
 tra cloth, $3 25. 
 
 _ We cannot withhold from this work our high commenda- 
 tion. Students and practitioners will find it an invaluable 
 teacher and guide upon every topic connected with this de- 
 partment.— A'ew York Medical Gazette. 
 
 A work of the very highest importance— a work by itself.— 
 London Meii. Gazette. 
 
 Ligature of the Facial Artery 
 
66 
 
 BLANCHARD AND LEA'S 
 
 Apforatusfor Operation for Hare-Lip. 
 
 Excision of Scapula. 
 
 A SYSTEM OF PRACTICAL SURGERY. 
 
 BY WILLIAM FERGUSSON, F. E. S., 
 
 Professor of Surgery in King's College, London. 
 
 ^ami\ %.rcitvi£wsi, from i\t %\jixii anir ©niargeitr ITonboit ®bition. 
 
 WITH THREE HUNDRED AND NINETY-THREE ILLUSTRATIONS ON ■WOOD. 
 
 I7i one large and very handsome octavo volume, of over 600 pages, leather, $3 00. 
 
 No work was ever written which more nearly com- 
 prehended the necessities of the student and practi- 
 tioner, and was more carefully arranged to that single 
 purpose, than this. — JV. Y. Med. and Surg. Journal. 
 
 The addition of many new pages makes this work 
 more than ever indispensable to the student and 
 practitioner. — JSanking's Abstract. 
 
 For the general practitioner who does not make a 
 specialty of surgery, it is certainly invaluable The 
 style is concise, pointed, and clear. The descriptions 
 
 of the various operations are concentrated and accu- 
 rate, so that in cases of emergency, the principles of 
 the most difficult operations may be obtained by a 
 reference of a few moments to its pages. — Western 
 Lancet. 
 
 Among the numerous works upon Surgerv publish- 
 ed of late years, we know of none we value more highly 
 than the one before us. It is, perhaps, the very best 
 we have for a text-book and for ordinary reference, 
 being concise and eminently practical. — Southern Med. 
 and Surg Journal. 
 
 OPERATIYE SURGERY; 
 
 BASED ON NORMAL AND PATPIOLOGIOAL ANATOMY. 
 BY J. F. MALaAIGNE. 
 
 TRANSLATED FROM THE FRENCH, BY FREDERIC BRITTAN, M. D., &c. 
 
 ILLUSTRATED BY WOOD-ENGRAVINGS, 
 FROM DESIGNS BY DR. WESTMACOTT. 
 
 In one neat octavo volume, of 564 pages, extra 
 cloth, $2 25. 
 
 We have long been accustomed to refer to it as one 
 of the most valuable textbooks in our library. — 
 Buffalo Med. and Surg. Journal. 
 
 Certainly one of the best books published on opera- 
 tive surgery. — Edinburgh Medical Journal. 
 
 To express in a few words our opinion of Malgaigne's 
 work, we unhesitatingly pronounce it the very best 
 guide in surgical operations that has come before the 
 profession in any language. — Charleston Medical and 
 Surgical Journal. Cheiloplasly of the Lower Lip. 
 
MEDICAL AND SCIENTIFIC PUBLICATIONS. 
 
 67 
 
 New and much Improved Edition — (Just Issued.) 
 
 In one 
 
 very handsome 
 
 royal 12mo. volume, 
 
 of 360 pages, 
 
 with 181 Illustrations; 
 
 leather, $1 50 ; 
 
 extra cloth, $1 40. 
 
 Opening Abscess. 
 
 ON BANDAGING, 
 
 AND OTHER OPERATIONS OF MINOR SURGERY. 
 BY F. W. SARGENT, M. D., 
 
 One of the Surgeons to Wills's Hospital, &c. 
 NEW EDITION, REVISED AND ENLARGED. 
 
 This very useful little work has long been a favorite with practition- 
 ers and students. The recent call for a new edition lias induced its 
 author to make numerous important additions. A slii;ht alteration 
 in the size of the page has enabled liira to introduce the new matter, 
 to the extent of some fifty pages of the former edition, at the same 
 time that his volume is rendered still more compact than its less com- 
 prehensive predecessors. A double gain is thus effected, which, in a 
 vade-mecum of this kind, is a material improvement. — A9n. Medical 
 Journal. 
 
 Sargent's Minor Surgery has always been popular, and deservedly 
 so. It furnishes that knowledge of the most frequently requisite per- 
 formances of surgical art which cannot be entirely understood by at- 
 tending clinical lectures. The art of bandaging, which is regularly 
 taught in Europe, is very frequently overlooked by teachers in this 
 country; the student and junior practitioner, therefore, may often re- 
 quire that knowledge which this little volume so tersely and happily 
 supplies. It is neatly printed and copiously illustrated by the enter- 
 prising publishers, and should be possessed by all who desire to be 
 thoroughly conversant with the details of this branch of our art. — 
 Charleston Med. Joitrn. and Review. 
 
 The author has selected, arranged, and elucidated the subject-matter 
 of his work in a masterly manner. Here the student will find nothing 
 but what is essential he should know well and never forget — the alpha- 
 bet of a surgical education. For practical utility and comprehensive 
 terseness of language, this volume has already earned itself a reputation; and it is almost a work of super- 
 erogation, upon our part, earnestly to recommend it to those for whom it is designed — the younger surgeon 
 and student. — Louisville Review, Nov. 1856. 
 
 We have never examined a work which has better fulfilled its mission. Dr. S. has given in a portable and 
 neat volume an admirably illustrated summary of theory and practice, in relation to implements, bandages, 
 fractures, apparatus, dislocations, and other cognate subjects appertaining to the domain of Minor Surgery. — 
 N. O. Med. and Surg. Journal. 
 
 Foicr-tailed Bandage/or 
 the Head. 
 
 MINOR SURGERY; 
 
 OR, HINTS ON THE EVERY-DAY DUTIES OF THE SURGEON. 
 BY HENRY H. SMITH, M. D., 
 
 Professor of Surgery in the University of Pennsylvania, &c. 
 
 THIRD EDITION, "WITH NUMEROUS ADDITIONS. 
 
 ILLUSTRATED BY 
 
 In one large royal 12mo. volume, of over 450 pages, leather, $2 25 ; extra cloth, $2 00. 
 
 No young practitioner should be without this little 
 volume; and we venture to assert, that it may be 
 consulted by the senior members of the profession 
 
 with more real benefit, than the more voluminous 
 works. — Western Lancet. 
 
6S 
 
 BLANCHARD AND LEA'S 
 
 A NEW WOKK ON THE TJKINARY OKGANS— Now Ready (1858). 
 
 DISEASES OE THE~URINAEY ORGANS: 
 
 A COMPENDIUM OF THEIR DIAGNOSIS, PATHOLOGY, AND TREATMENT. 
 
 Bv WILLIAM WALLACE MORLAND, M.D,, 
 
 Fellow of the Massachusetts Medical Society, &c. 
 
 WITH ILLUSTRATIONS. 
 
 hi one large and handsome octavo volume^ of about 600 pp.^ 
 extra cloth. Price §3 50. 
 
 This volume, it is hoped, will supply the want of a work 
 which within convenient compass should present ihe whole 
 subject of the disease* to which all ihe urinary organs are 
 liable, with their treatment, both medical and surgical. The 
 aim of the author has bien throughout to present the results 
 of the most recent investigations in a clear and succinct man 
 ner, omitting nothing of practical importance without at the 
 same time embarrassing the student with unnecessary specu- 
 lations. Various elaborate and important works have recent- 
 ly appeared on different departments of the subject, but none, 
 it is believed, which thoroughly covers the whole ground in 
 
 ^ , ^„ , ■ , ^^ , , , the manner which Dr. Morlaud has attempted. 
 
 Tube filled with Oil-globules "^ 
 
 {Fatty Degeneration of Kidney). 
 
 This work is one of much merit, worthy of the care- 
 ful perusal of every physician, and deservinj; of a 
 place in his library, as a book of reference. We are 
 in want of just such books as this work of Dr. Mor- 
 land. We cannot dismiss Dr. M.'s work without the 
 declaration that it is a good book, for which he merits, 
 and we hope he will receive, the substantial thanks of 
 the profession. — Med. and Surg. Reporter, Nov. 5, 1858. 
 
 The composition of these essays necessitated a care- 
 ful examination of contemporary literature, and in 
 the subsequent embodiment of them in the present 
 systematic volume, all that has since transpired has 
 been conscientiou.sly collected and well digested, bring- 
 ing the work up to the latest advances of surgical 
 science. — NashviUe Monthly Record, Nov. 1858. 
 
 Ne-w and Enlarged Edition — (Just Issued.) 
 THE PRINCIPLES AND PRACTICE OF 
 
 OPHTHALMIC MEDICINE AND SUPiGERY. 
 
 BY T. WHARTON JONES, F. R. S., 
 
 Professor of Ophthalmic ^Medicine and Surgery in 
 
 University College, London. 
 
 "With 110 Illustrations. 
 
 §£tonb ^m^ritait ©bition, 
 WITH ADDITIONS, 
 
 FROM THE SECOND AND REVISED ENGLISH 
 EDITION. 
 
 In one large and handsome royal \2mo. vol., 
 extra cloth, of 500 pagts, $1 50. 
 
 This favorite manual has received from 
 the author a very thorough revision, bringing 
 it fully up to the present state of the sub- 
 ject. His very extensive additions, and those 
 of the editor, have, however, been accom- 
 modated by an increase in the size of the 
 page, without enlarging the bulk of the vo- 
 lume, and the work has accordingly been re- 
 tained at its former very moderate price. 
 
 We have always regarded Mr. Jones's Ophthalmic 
 Medicine and Surgery as incomparably the very best 
 manual ever published, in the English language, upon 
 the subjects of which it treats. The second edition ' 
 appears under many advantages over the first; and 
 we may safely assert of it, that we know of no other 
 work on the eye we can so confidently reex)mmend to 
 the student for study, or to the practitioner for prac- , 
 tice. — Montreal Med. Chronicle. June, 1856. | 
 
 Granular Conjunctiva^ with Pannus. 
 
 This popular work on Diseases of the Eye is a stand- 
 ard authority both in England and America. It ably 
 discusses the subject of Ophthalmic Pathology and 
 Therapeutics, is cheaper than the larger works upon 
 these topics, and we commend it to our readers as a 
 most valuable guide in the successful management of 
 this troublesome clasa of diseases. — Kasliville Journal 
 of Medicine. Sept. 1856. 
 
MEDICAL AND SCIENTIFIC PUBLICATIONS. 
 
 69 
 
 New and Enlarged Edition— (Recently Issued.) 
 
 Introduction of the Catheter. 
 
 A PRACTICAL TREATISE 
 
 ON THE 
 
 DISEASES, INJURIES, AND MALFORMATIONS 
 
 OF THE 
 
 URINARY BLADDER, THE PROSTATE GLAND, AND THE URETHRA. 
 BY S. D. GROSS, M. D., 
 
 Professor of Surgery in the Jefferson Medical College of Philadelphia. 
 SECOND EDITION, REVISED AND MUCH ENLABGED. 
 
 SStitlj one IjituirKb anb ng^tg-foar Illustrations. 
 
 In one large and very handsome octavo volume, of over nine hundred pages, extra cloth, $4 75 ; 
 leather, raised bands, $5 25. 
 
 Whoever will peruse the vast amount of valuable 
 practical information it contain?, and which we have 
 been unable even to notice, will, we think, agree with 
 us. that there is no work in the English language 
 which can make any just pretensions to be its equal. 
 — iV. Y. Journal of Medicine. 
 
 On the appearance of the first edition of this work, 
 the leading English medical review predicted that it 
 ■would have a " permanent place in the literature of 
 surgery worthy to rank with the best works of the 
 present age." This prediction has been amply fulfilled. 
 Dr. Gross's treatise has been found to supply complete- 
 ly the want which has been felt ever since the eleva- 
 tion of surgery to the rank of science, of a good prac- 
 tical treatise on the diseases of the bladder and its 
 accessory organs. Philosophical in its design, me- 
 thodical in its arrangements, ample and sound in its 
 
 practical details, it may in truth be said to leave 
 scarcely anything to be desired on so important a sub- 
 ject, and with the additions and modifications result- 
 ing from future discoveries and improvements, it will 
 probably remain one of the most valuable works on 
 this subject so long as the science of medicine shall 
 exist. — Boston Med. and Surg. Journal. 
 
 A volume replete with truths and principles of the 
 utmost value in the investigation of these diseases. — 
 American Medical Journal. 
 
 Dr. Gross has brought all his learning, experience, 
 tact, and judgment to the task, and has produced a 
 work worthy of his high reputation. We feel per- 
 fectly safe in recommending it to our readers as a mo- 
 nograph unequalled in interest and practical value 
 by any other on the subject in our language. — The 
 Western Journal of Medicine and Surgery. 
 
 INSTITUTES AND PRACTICE OF SURGERY; 
 
 Being Outlines of a Course of Lectures by William Gibson, M. D., late Professor of Surgery 
 in the University of Pennsylvania. Eighth edition, improved and altered. With thirty-ibur 
 Plates. In two handsome octavo volumes, containing about one thousand pages. Leather, 
 raised bands, $6 50. 
 
70 
 
 BLANCHARD AND LEA'S 
 
 New and Enlarged Edition — (Just Issued.) 
 
 A PRACTICAL TREATISE 
 
 DISEASES OF THE TESTIS, 
 
 AND OF THE 
 
 SPERMATIC CORD AND SCROTUM. 
 
 BY T. B. CURLING, F.R.S., 
 
 Surgeon to the London Hospital, &c. 
 
 SECOND AMERICAN, 
 
 FROM THE 
 
 Second Revised and Enlarged London Edition. 
 
 Watlj nnmttau^ lUastrations. 
 
 In one very handsome octavo volume, of over 
 AQO pages, extra cloth, $2 00. 
 
 
 Chimney-Sweeper''s Canter. 
 
 To make room for additional matter, the anatomi- 
 cal introduction was omitted in the new London edi- 
 tion, but we are glad to notice that the American 
 publishers retain it. It is by far the best anatomy of 
 the testis we possess, and should by all means accom- 
 pany the treatise, giving it, as it does, a completeness 
 of detail which satisfies the want of the practitioner. 
 The reputation of the work has been so long and 
 thoroughly established that the labor of the critic 
 may be confined to the simple announcement of its 
 republication. Many who, since the exhaustion of 
 the previous edition have been unable to procure it. 
 will doubtless profit by this hint. We need only add 
 that it is the most complete scientific and practical 
 account of diseases of the testis in the language. — 
 Buffalo Med. Journal, Sept. 1856. 
 
 We have taken considerable pains to compare the 
 present with the previous edition, and take pleasure 
 in stating as the result of our investigations that it 
 is in every way superior to it. In style and precision 
 of language there is a marked improvement, a large 
 amount of new and important matter has been intro- 
 duced by the author, while his increased experience 
 has enabled him to speak positively on many ques- 
 tions in which his opinions were indecisively or difi'er- 
 ently given in the first edition. As it now stands, we 
 can unhesitatingly speak of it as the first work upon 
 the subjects it treats of in our language, one worthy 
 in all respects of the confidence and approbation of 
 the profession.— 3/ed. Examiner, Sept. 1856. 
 
 A PRACTICAL TREATISE 
 
 FOEEIGN BODIES 
 
 / BY S. D. GROSS, M. D., 
 
 Professor of Surgery in Jefferson Medical College, Philadelphia. 
 
 Mxi\ lllastrations. 
 
 In one handsome octavo volume, extra cloth, of nearly 
 bOO ])ages J price $2 75. 
 
 A very elaborate work. It is a complete summary of the 
 whole subject, and will be a useful book of reference.— .Bniis/t 
 and Foreign Medico- Chirurg. Review. 
 
 A highly valuable book of reference on a most important sub- 
 ject in the practice of medicine. We conclude by recommend- 
 ing it to our readers, fully persuaded that its perusal will afford 
 them much practical information well conveyed, evidently de- 
 rived from considerable experience and deduced from an ample 
 collection of iejiis.— Dublin Quarterly Journal. 
 
 Unusual Co^trse of the Innominata. 
 
MEDICAL AND SCIENTIFIC PUBLICATIONS. 
 
 71 
 
 PRACTICAL OBSERVATIONS ON AURAL SURGERY, 
 
 AND THE NATURE AND TREATMENT OF 
 
 DISEASES OE THE E^R. 
 
 IM'iib llhistrnlious. 
 BY WILLIAM R. WILDE, 
 
 Surgeon to St. Mark's Ophthalmic Hospital, &c. 
 In one very liandsomc octavo volume, of about Jive hundred pages, extra cloth. S2 80. 
 
 Instrument for removing Aural Polypus. 
 
 Preparing for early publication. 
 
 A TREATISE ON FRACTURES AND DISLOCATIONS. 
 
 BY FRANK H. HAMILTON, M.D., 
 Professor of Surgery in Buffalo Medical College. 
 
 In one handsome octavo volume, toith numerous Illustrations. 
 
 The numerous improvements which this important branch of surgery has received from the 
 skill and ingenuity of American surgeons, renders particularly appropriate and valuable a com- 
 plete and systematic original work on the subject. The esf^ays which Professor Hamilton has 
 published on kindred topics are already widely and favorably known, and give earnest that his 
 forthcoming work will prove indispensable, both as a text-book for the student, and as a guide 
 for the practitioner. 
 
 A TREATISE ON 
 
 DISLOCATION'S km FRACTURES OF THE JOINTS. 
 
 By Sir Astley Cooper, Bart., F. R. S., &c. A new edition, much enlarged. Edited by Brans- 
 BY B Cooper, F R S. With additional observations by Prof. John C. Warren. In one 
 handsome octavo volume of 500 pages; with 132 Illustrations, extra cloth, $3 25. 
 
 LECTURES ON THE PRINCIPLES AND PRACTICE OF SURGERY. 
 
 By Bransby B. Cooper, F. R. S., Senior Surgeon to Guy's Hospital, &c. In one large 
 octavo volume, of seven hundred and fifty pages, extra cloth, $3 00. 
 
 COOPER ON THE STRUCTURE AND DISEASES I COOPER ON THE ANATOMY AND DISEASES OF 
 OF THE TESTIS. AND ON THE THYMUS! THE BREAST, with Twenty-five Miscellaneous and 
 GLAND. One vol., imperial Svo., with 177 figures Surgical Papers. One large vol., imperial Svo., with 
 on 29 plates, extra cloth, $2 00. I 252 figures on 36 plates, extra cloth, $2 50. 
 
 STANLEY'S TREATISE ON DISEASES OF THE I BRODIE'S CLINICAL LECTURES ON SURGERY. 
 BONES. In one vol. Svo., extra cloth, 28e pp., $1 50. | One vol. Svo., cloth, 350 pp., $1 25. 
 
 THE LAWS OF HEALTH IN RELATION TO MIND 1 
 AND BODY. A Series of Letter? from an old Prac- 
 titioner to a Patient. By Lionel J ohm Beale, M. R. 
 
 C. S., &c. In one handsome volume, royal 12mo., 
 extra cloth, SO cents. 
 
72 
 
 BLANCHARD AND LEA'S 
 
 Lately Published. 
 
 la one large f 
 
 and closely printed 
 
 octavo volume, 
 
 of over 
 
 1000 pages, 
 
 beautifu II y 
 
 illustrated with 
 
 two plates 
 
 and 
 
 Cysticerciis in Anterior Chamber. 1&" WOOd-CUtS. 
 
 Strongly bound in leather, with raised bands, $6 25. 
 
 Head and Neck of Cysticercus, 
 magnified. 
 
 A PRACTICAL TREATISE ON 
 
 DISEASES OF THE EYE. 
 
 BY WILLIAM MACKENZIE, M. D., 
 
 Surgeon Oculist in Scotland in Ordinary to her Majesty, &c. 
 TO WHICH IS PEEFIXED, 
 
 AN ANATOMICAL INTRODUCTION, 
 BY T. WHARTON JONES, F.R.S., &c. 
 
 Jrom i\z Joutt^ Hetris^b amb inlargtir IToniron ®bition. 
 With Notes and Additions, bit ADDINELL HEWSON, M. D., 
 
 One of the Surgeons to Wills's Hospital, &c. 
 
 Operation for Strabismus. 
 
 The treatise of Dr. Mackenzie indisputably holds the 
 first place, and forms, in respect of loarninp: and re- 
 search, an Encyclopfedia unetiualled in extent by any 
 other work of the kind, either English or foreign. — 
 Dixon mi Diseases of the Eye. 
 
 Few modern hooks on any department of medicine 
 or sm'gery have met with such extended circulation, 
 or have procured for their authors a like amount of 
 European celebrity. The immense research which it 
 displayed, the thorough acquaintance with the subject, 
 practically as well as theoretically, and the able man- 
 ner in which the author's stores of learning and expe- 
 rience were rendered available for general use, at once 
 procured for the first edition, as well on the continent 
 as in this country, that high position as a standard 
 work which each successive edition has more firmly 
 established, in spite of the attractions of several rivals 
 of no mean ability. This, the fourth edition, has heen 
 in a great measure rewritten ; new matter, to the ex- 
 tent of one hundred and fifty pages, has been added, 
 and in several instances formerly expressed opinions 
 have been modified in accordance with the advances 
 in the science which have been made of late years. 
 Nothing worthy of repetition upon any branch of the 
 subject appears to have escaped the author's notice. 
 We consider it the duty of every one who has the love 
 of his profession and the welfare of his patient at heart, 
 to make himself familiar with this the most complete 
 work in the English language upon the diseases of the 
 eye. — Med. Times and Gazette. 
 
 The fourth edition of this standard work will no 
 doubt he as fully appreciated as the three former edi- 
 tions. It is unnecessary to say a word in its praise, 
 for the verdict has already been passed upon it by the 
 most competent judges, and "Mackenzie on the Eye" 
 has justly obtained a reputation which it is no figure 
 of speech to call world-wide. — British and Foreign 
 Medico-Chirurgical Review. 
 
 This new edition of Dr. Mackenzie's celebrated trear 
 tise on diseases of the eye, is truly a miracle of in- 
 dustry and learning. We need scarcely say that he 
 has entirely exhausted the subject of his specialty. — 
 Dublin Quarterly Journal. 
 
MEDICAL AND SCIENTIFIC PUBLICATIONS. 
 
 73 
 
 A TREATISE ON DISEASES OF THE EYE. 
 
 BY W. LAWRENCE, F. E. S,, 
 
 Surgeon to St. Bartholomew's Hospital, &c. 
 
 A NEW Edition, 
 
 EDITED, WITH NUMEROUS ADDITIONS, 
 
 AND 
 
 STtoo Ijuubrcb Hnb fortg-tljree llUxstrations, 
 BY ISAAC HAYS, M. D., 
 
 Surgeon to VVills's Hospital, &c. 
 
 In one large and handsome octavo volume, of 950 pages, leather, raised bands, $5 00. 
 
 This work is so universally recog-nized as the standard authority on the subject, that the pub- 
 lishers in presenting- this new edition have only to remark that in its preparation the editor has 
 carefully revised every portion, introducing additions and illustrations wherever the advance of 
 science has rendered them necessary or desirable, constituting it a complete and thorough expo- 
 nent of the most advanced state of the subject. 
 
 A NEW TEXT-BOOK OX INSANITY— Now Ready (1858). 
 
 A MANUAL OF PSYCHOLOGICAL MEDICINE; 
 
 CONTAINING 
 
 THE HISTORY. NOSOLOGY, DESCRIPTION. STATISTICS. DIAGNOSIS. PATHOLOGY. AND 
 
 TREATMENT OF 
 
 INSANITY. 
 
 Br J. C. BUCKNILL, M. D., 
 
 Medical Superintendent of the JDevon County Lunatic Asylum, 
 
 AND DANIEL H. TUKE, M.D., 
 
 Visiting Medical Officer to the York Retreat. 
 
 WITH A PLATE. 
 
 In one very neat octavo volume of 536 pages ; extra cloth, f 3. 
 
 The increase of mental disease in its various forms, and the difficult questions to which it is 
 constantly giving rise, render the subject one of daily enhanced interest, requiring on the part of 
 the physician a constantly greater familiarity with this, the most perplexing branch of his pro- 
 fession. At the same time there has been for some years no work accessible in this country, 
 presenting the results of recent investigations in the Diagnosis and Prognosis of insanity, and 
 the greatly improved methods of treatment which have done so much in alleviating the condition 
 or restoring the health of the insane. To fill this vacancy the publishers present this volume, 
 assured that the distinguished reputation and experience of the authors will entitle it at once to 
 the Confidence of both student and practitioner. Its scope may be gathered from the declaration 
 of the authors that "their aim has been to supply a text-book which may serve as a guide in the 
 acqui.-ition of such knowledge, sulTiciently elementary to be adapted to the wants of the student, 
 and sufficiently modern in its views and explicit in its teaching to suffice for the demands of the 
 practitioner." 
 
 Every physician ought to have some work on In- 
 sanity, and, as most can afford to have hut one, we 
 would recommend this unreservedly as the hest. It 
 is sufficiently full, it is clear in its statements and de- 
 scriptions, and very discriminating in its practical 
 views. . . . We have seldom met with a collection of 
 such judicious views of the treatment of disease as 
 are in this chapter presented of the treatment of in- 
 sanity, and we would commend them to the careful 
 examination of the profession, not only from their 
 value in their .special hearing on this disease, but also 
 on account of their development of the true princi- 
 ples of the treatment of disease.s generally. — Am. Med. 
 Journal, Oct. 1858. 
 
 It will, we suppose, he generally gratifyinjr to the 
 members of the specialty, that at a time when in- 
 creased attention is being paid to mental disease by 
 the profession, a representative treatise has been un- 
 dertaken by gentlemen so well and so favorably knowr) 
 as Drs. Bucknill and Tuke. Their scientific and lite- 
 rary ability, with their large practical acquaintance 
 with their subject, should indeed eminently tit them 
 for the task; and. taken as a whole, the result of their 
 labors will not fail to answer a just anticipation. We 
 do not know where anything can be found in the lite- 
 rature of the specialty to compare with these essays, 
 
 in complete and logical treatment, and the clear, prac- 
 tical manner in which their subjects are discussed. 
 They will be cited as authority wherever the language 
 is used, and will, no doubt, be extensively translated. 
 — Am. Journ. of Insanity, Oct. 1858. 
 
 We know of no one book which so fully embraces 
 everything connected with the insane. Altogether, 
 we can confidently recommend the work to our read- 
 ers; we believe they will find it one which deserves 
 to be valued even beyond any praise which we have 
 deemed it our duty to accord to a volume of both great 
 medical and great moral merit. — Dublin Quarterly 
 Jom-nal, Aug. 1858. 
 
 In conclusion, we can say, in all sincerity, that sel- 
 dom have the expectations raised by the language of 
 the Preface been so fully realized in the execution of 
 the work as in the volume of Drs Bucknill and Tuke. 
 Its publication removes all excuse that may, hitherto, 
 have been alleged by students and practitioners of 
 medicine for neglect of the subject owing to the want 
 of a work of insanity for ready reference — one which, 
 like the present, contains sound principles, enforced 
 and illustrated by a series of pertinent and well- 
 digested facts, evidently accumulated by long person- 
 al experience and much reading — North American 
 Medico-Chirurgical Review, Sept. 1858. 
 
74 
 
 BLANCHARD & LEA'S 
 
 New and Enlarged Edition. 
 
 MEDICAL JURISPRUDENCE. 
 
 BY ALFRED S. TAYLOR, M. D., F. R. S., 
 
 Lecturer on Medical Jurisprudence and Chemistry in Guy's Hospital, &c. 
 Fourtli American, from tlie Fifth and Improved liOndon Kdltion. 
 
 WITH NOTES AND REFERENCES TO AMERICAN DECISIONS, 
 
 BY EDWARD HARTSHORNE, M. D. 
 
 In one large octavo volume, of seven hundred closely printed pages, leather, $3 00. 
 
 This standard work has lately received a very thorough revision at the hands of tho author, 
 who has introduced whatever was necessary to render it complete and satisfactory in carrying 
 out the objects in view. The editor has likewise used every exertion to make it equally tho- 
 rough with regard to all matters relating to the practice of this country. In doing this, he has 
 carefully examined all that has appeared on the subject since the publication of the last edition, and 
 has incorporated all the new information thus presented. The work has thus been considerably 
 increased in size, notwithstanding which, it has been kept at its former very moderate price, 
 and in every respect it will be found worthy of a continuance of the remarkable favor which 
 has carried it through so many editions on both sides of the Atlantic. 
 
 We hazard little in affirming our belief that Taylor's 
 Medical Jurisprudence is the best manual on its sub- 
 ject in any language. It has so long occupied the 
 first rank among our most popular text-books, and is 
 so favorably known to our readers of every kind, legal, 
 medical, and general, that the mere announcement 
 of a new edition is an all-sufficient recommendation. 
 The previous efforts of its author and editor affijrd 
 ample guaranty of continued improvements in each 
 new issue of their work ; and we need only to make a 
 cursory examination of the volume before us to be 
 satisfied that the additions and alterations are both 
 numerous and important, and such as fully to sustain 
 the previous reputation of the manual, and that of 
 its indefatigable author — Med. Examiner. 
 
 The work of Dr. Taylor is now recognized by the pro- 
 fession generally as ranking among the best element- 
 ary treatises on medical jurisprudence in the English 
 language. We know of none in which the subject may 
 be more profitably studied; no one better adapted for 
 casual reference with the view to refresh the memory 
 in respect to any especial question within the general 
 scope of forensic medicine. The author has, with 
 admirable judgment, selected from the immense mass 
 of materials at his disposal those best calculated to re- 
 
 present the actual condition of medico-legal know- 
 ledge, and has arranged these in a manner calculated 
 to present the requisite information with that clear- 
 ness and precision so essential in an elementary trea- 
 tise. — Am. Journ. Med. Sciences. 
 
 It is at once comprehensive and eminently practical, 
 and by universal consent stands at the head of Ame- 
 rican and British legal medicine. It should be in the 
 possession of every physician, as the subject is one of 
 great and increasing importance to the public as well 
 as to the profession. — .S'^ Louis Med. and Surg. Journal. 
 
 This work of Dr. Taylor's is generally acknowledged 
 to be one of the ablest extant on the subject of medical 
 jurisprudence. It is certainly one of the most attract- 
 ive books that we have met with ; supplying so much 
 both to interest and instruct, that we do not hesitate 
 to affirm that after having once commenced its peru- 
 sal, few could be prevailed upon to desist before com- 
 pleting it. In the last London edition, all the newly 
 observed and accurately recorded facts have been in- 
 serted, including much that is recent of Chemical, 
 Microscopical, and Pathological research, besides pa- 
 pers on numerous subjects never before published. — 
 Charleston Medical Journal and Review. 
 
 By the same Author— Now Ready (June 1859). 
 
 ON x>oisoisrs, 
 
 IN RELATION TO MEDICAL JURISPRUDENCE AND MEDICINE. 
 
 Second American, from the Second and Revised English Edition. 
 
 In one large octavo volume of Ibb pages, leather, $3 50. 
 
 The length of time which has elapsed since the first appearance of this work has wrought so 
 great a change in the subject as to require a very thorough revision to adapt the volume to the 
 present wants of the profession. The rapid advance of Chemistry has introduced into use many 
 new substances which may become fatal through accident, carelessness, or design — while at the 
 same time it has likewise designated new and more exact modes of counteraciing or detecting 
 those previously treated of. Mr. Taylor's position as the leading medical jurist of England, has 
 during this period conferred on him extraordinary advantages in acquiring experience in all that 
 relates to this department, nearly all cases of moment being referred to him for examination, as 
 an expert whose testimony is generally accepted as final. The results of his labors, therefore, 
 as gathered together in this volume, carefully weighed and sified, and presented in the clear and 
 intelligible style for which he is noted, may be received as an acknowledged authority, and as 
 a guide to be followed with implicit confidence. 
 
 In his Preface the author says : — 
 
 " My space has been limited, and I have endeavored to fill it with materials which may be of 
 profit to the practitioners of law and medicine, for whose especial use this volume is intended. 
 Under this view the plan of the former edition has been entirely changed. Many chapters have 
 been struck out, and an equal number of new chapters introduced. The requirements of a pe 
 riod dating no longer ago than ten years are different from those of the present day, and it is 
 the duty of an author, so far as it may be in his power and consistent with the scope of his 
 labors, to fulfil these requirements by an entire remodelling of his subject." 
 
 The most elaborate work on the subject that our 
 literature possesses. — British and Foreign Medico-Chi- 
 rurgical Review. 
 
 It contains a vast body of facts, which embrace all 
 that is important in toxicology, all that is necessary 
 to the guidance of the medical jurist, and all that can 
 be desired by the lawyer. — Medico-Chirurg. Review. 
 
 One of the most practical and trustworthy works 
 on Poisons in our language. — Western Jaum. of Med. 
 
 It is, so far as our knowledge extends, incomparably 
 the best upon the subject; in the highest degree cre- 
 ditable to the author, entirely trustworthy, and indis- 
 pensable to the student and practitioner. — N. Y. An- 
 nalist. 
 
MEDICAL AND SCIENTIFIC PUBLICATIONS. 
 
 75 
 
 A Series of Text-books on Physical Science. 
 HANDBOOKS 
 
 OF 
 
 MTURAL PHILOSOPHY AND ASTRONOMY. 
 
 BY DIONYSIUS LARDNER, D. C. L., 
 
 Formerly Professor of Natural Philosophy and Astronomy in University College, London. 
 
 This valuable series is now complete, consisting- of three Courses, as follows : — 
 
 FIRST COURSE. 
 
 51ECHANICS, RYDROSTATICS, HYDRAULICS, PNEUMATICS, SOUND, AND OPTICS. 
 
 In one large royal \2mo. volume of 750 pages, with 424 illustrations / $1 75. 
 SECOND COURSE. 
 
 HEAT, MAGNETISM, COMMON ELECTRICITY, AND VOLTAIC ELECTRICITY. 
 
 In one royal 12mo, volume of AbO 2:)ages, with 244 illustrations j $1 25. 
 
 THIRD COURSE. 
 
 ASTRONOMY AND METEOROLOGY. 
 
 In one very large royal 12»io. volume of nearly 800 pages, with 2>1 pilates and over 200 illus- 
 trations. $2. 
 
 These volumes can be had either separately or in uniform sets, containing 
 
 About two thousand pages, and nearly one thousand Illustrations on Steel and Wood. 
 
 To accommodate those who desire separate treatises on the leadmg departments of Natural 
 Philosophy, the First Course may also be had divided in three portions, as follows : — 
 
 Part I.— MECHANICS, price 70 cents. 
 
 «' II.— HYDROSTATICS, HYDRAULICS, PNEUMATICS, and SOUND, price 60 cts. 
 
 " III.— OPTICS, price 70 cents. 
 
 It will thus be seen that this work furnishes either a complete course of instruction on these 
 subjects, or separate treatises on all the different branches of Physical Science. 
 
 The object of the author has been to prepare a work suited equally for the collegiate, acade- 
 mical, and private st udent, who may desire to acquaint himself with the present state of science, 
 in its most advanced condition, without pursuing it through its mathematical consequences and 
 details. Great attention has been paid throughout the w^ork to elucidating the principles ad- 
 vanced by their practical applications to the wants and purposes of civilized life, a task to which 
 Dr. Lardner's immense and varied knowledge, and his singular felicity and clearness of illustra- 
 tion render him admirably fitted. This peculiarity of the work recommends it especially as the 
 text-book for a practical age and country such as ours, as it interests the student's mind by show- 
 ing him the utility of his studies, while it directs his attention to the further extension of that 
 utility by the fulness of its examples. Its extensive adoption in many of our most distinguished 
 colleges and seminaries is sufficient proof of the skill with which the author's intentions have 
 been carried out. 
 
 From Prof. W. L. Brown, Oakland College, Miss. 
 I consider them most admirably suited for the pur- 
 poses designed by the author — indeed, as the very 
 best popular works on physical science with which I 
 am acquainted The '-Third Course," on Astronomy, 
 is especially valuable; its magnificent engravings 
 and lucid explanations make it a most desirable text- 
 book. 
 
 From Sev. J. 6. Ralston, JVorristown, Pa. 
 Lardner's Meteorology and Astronomy is a fit com- 
 panion for his First and Second Course. It is won- 
 derfully minute, and yet not prolix. The principles 
 of Astronomy are probably as clearly defined and 
 judiciously arranged in this book as they can be. I 
 expect to introduce it in my school. 
 
 From S. Schooler, Esq., Hanover Academy, Va. 
 The three volumes constitute a body of information 
 and detail on nearly the whole range of physical sci- 
 ence which is not to be found together in any other 
 publication with which I am acquainted. I hope that 
 
 these works may be the means of inducing many of 
 our youth to devote themselves to the development 
 of the Laws of Nature, and the application of them 
 to industry, and that tliey may be the vehicle for con- 
 veying sound information and food for thought to 
 every man who aspires to be well educated. 
 
 From M. Conant, State Normal School, Mass. 
 This is a treatise admirably adapted to its purpose. 
 For the accurate knowledge it unfolds, and the very 
 popular dress it appears in, I think I have met with 
 nothing like it. I shall advise the students of the 
 Normal School to add this to your edition of Lardner's 
 Mechanics, &c. 
 
 From Prof. E. Everett, New Orleans. 
 I am already acquainted with the merits of this 
 book, having had occasion to consult it in teaching 
 the branches of which it treats, and I cannot give you 
 a stronger assurance of my high opinion of it than the 
 simple fact that I have selected it as the text-book of 
 Physics in the course of study which I have just fixed 
 upon for a new college to be established here. 
 
76 
 
 BLANCHARD AND LEA'S 
 
 In one very handsome 
 
 oclavo volume, 
 
 of nearly six hundred and fifty pages, 
 
 with 
 
 over five hundred 
 
 beautiful Illustrations on wood, 
 
 and two colored Plates, 
 
 extra cloth, $3 50. 
 
 Hart's Calorimotor 
 
 Structure of the Larynx. 
 
 PRKiCIPLES OF PHYSICS AND METEOPiOLOGY. 
 
 BY J. MULLER, 
 
 Professor of Physics at the University of Freiburg, &c. 
 Revised, with Additions, by R. E. GRIFFITH, M. D. 
 
 In the work before us, the first thing which strikes 
 us is the profusion of wood-cuts beyond what we 
 should have imagined any publisher could furnish at 
 the price— and very good cuts. The matter of the 
 work is sound, and ranges over the subjects well. The 
 manner is popular, and the author, though a mathe- 
 matician, introduces only formulae to look at now and 
 then, without algebraic processes. We strongly re- 
 commend this work, particularly for the libraries of 
 schools, mechanics' institutes, and the like. The pre- 
 sent volume contains excellent reading and reference 
 for those who are to have but one book on the subject. 
 — AtkencBum. 
 
 The plan adopted by Muller is simple ; it reminds 
 us of the excellent and popular treatise published 
 many years since by Dr. Arnott, but it takes a much 
 wider range of subjects. Like it, all the necessary 
 
 explanations are given in clear and concise language, 
 without more than an occasional reference to mathe- 
 matics; and the treatise is most abundantly illus- 
 trated with well-executed wood engravings. 
 
 The author has actually contrived to comprise in 
 about five hundred pages, including the space occupied 
 by illustrations, Mechanics, the laws of Motion. Acous- 
 tics, Light, Magnetism, Electricity, Galvanism, Electro- 
 Magnetism, Heat, and Meteorology. 
 
 Medical practitioners and students, even if they 
 have the means to procure, have certainly not the 
 time to study an elaborate treatise in every branch of 
 science; and the question therefore is, simply, whe- 
 ther they are to remain wholly ignorant of such sub- 
 jects, or to make a profitable use of the labors of those 
 who have the happy art of saying or suggesting much 
 in a small space. 
 
 ELEMENTS OF NATURAL PHILOSOPHY; 
 
 BEING AN EXPERIMENTAL INTRODUCTION TO THE PHYSICAL SCIENCES. 
 Illustrated with over three hundred wood-cuts. By Golding Bird, M. D., Assistant Physician 
 to Guy's Hospital. From the Third and Improved London edition. In one handsome royal 
 12mo. volume, of over 400 very large pages, on small type, leather, f 1 50 ; extra cloth, $1 '25. 
 
 ELEMENTS OF PHYSICS ; 
 
 OR, NATURAL PHILOSOPHY, GENERAL AND MEDICAL. Written for universal use 
 in plain, or non-technical language. By Neill Arnott, M. D. A new edition, revised and 
 corrected from the last English edition, with Additions, by Isaac Hays, M. D. With about 
 two hundred illustrations. In one octavo volume, of nearly five hundred pages, leather, $2 50. 
 
 ZOOPHYTES AND CORALS. 
 
 By James D. Dana. In one large imperial quarto volume, extra cloth, with wood-cuts. (U. S. 
 Exploring Expedition.) f 15 00. 
 
 Also, An Atlas to the above, in one imperial folio volume, half bound in morocco, with sixty- 
 one large plates, exquisitely colored after nature, f 30 00. 
 
 BY THE SAME ATJTHOE. 
 
 THE STRUCTURE AND CLASSIFICATION OF ZOOPHYTES, 
 volume, extra cloth. $4 50. 
 
 In one imperial quarto 
 
 ASPECTS OF NATURE 
 
 IN DIFFERENT LANDS AND DIFFERENT CLIMATES. With Scientific Elucidations. 
 By Alexander Von Humboldt. Translated by Mrs. Sabine. In one large and handsome 
 royal 12mo. volume, extra cloth. $1 00. 
 
MEDICAL AND SCIENTIFIC PUBLICATIONS, 
 
 77 
 
 HBRSCHEL'S ASTRONOMY. 
 
 OUTLINES OF ASTRONOMY. 
 
 BY SIR JOHN F. W. HERSCHEL, Bart., F. R. S., &c. 
 
 g. ncfa American, from tljc fourtlj anir nhm)i IToivbon tintioix. 
 
 In one handsome crown octavo volume, with numerous plates and loood-euts, extra cloth, $1 60; 
 
 or, half bound, leather backs and cloth sides, $1 75. 
 
 The present work is reprinted from the last London edition, which was carefully revised by 
 
 the author, and in which he embodies the latest investigations and discoveries. It may therefore 
 
 be re°-arded as fully on a level with the most advanced state of the science, and even better 
 
 adapted than its predecessors, as a full and reliable manual. 
 
 From Prof. A. Casivdl, Brown University, R. J. 
 As a work of reference and study for the more ad- 
 vanced pupils, who yet are not prepared to avail them- 
 selves of the higher mathematics, 1 know of no work 
 to be compared with it. 
 
 From Professor D. Olmsiead, Tale College. 
 A rich mine of all that is most valuable in modern 
 Astronomy. 
 
 THE PRINCIPLES OF 
 
 ANIMAL AND VEGETABLE PHYSIOLOGY. 
 
 A POPULAR TREATISE 
 
 ON THE 
 
 FUNCTIONS AND PHENOMENA 
 
 OF 
 
 ORGANIC LIFE. 
 
 BY J. STEVENSON BUSHNAN, M. D. 
 
 "With 102 Illustrations. J||)j| ii^...^ ... 
 
 Hill ' i^At'''' 4v1 I 
 
 In one very neat royal 12mo. vohime, of 234 s|| \vi| ^ ^i^^ 
 pages, extra cloth, 90 cents. % % il\jijlW^' 
 
 Spiracle of Fly. 
 
 The Illustrated Geographical Encyclopaedia. 
 
 THE ENCYCLOPJlDll OF GEOGRAPHY. 
 
 COMPRISING A COMPLETE DESCRIPTION OF THE EARTH, PHYSICAL, STATISTICAL, CIVIL, AND 
 
 POLITICAL. EXHIBITING ITS RELATION TO THE HEAVENLY BODIES, ITS PHYSICAL STRUC- 
 
 TtJRE, THE NATURAL HISTORY OF EACH COUNTRY, AND THE INDUSTRY, COMMERCE, 
 
 POLITICAL INSTITUTIONS, AND CIVIL AND SOCIAL STATE OP ALL NATIONS. 
 
 BY HUGH MURRAY, F. R. S. E., &c. 
 
 Assisted in Botany, by Professor HOOKER— Zoology, &c., by W. W. SWAINSON— Astrono- 
 my, &c., by Professor WALLACE— Geology, &c., by Professor JAMESON. 
 
 REVISED, WITH ADDITIONS, 
 
 BY THOMAS G. BRADFORD. 
 
 In three large octavo volumes, containing about nineteen hundred large imperial pages, and 
 
 ILLUSTRATED BY EIGHTY-TWO SMALL MAPS. 
 
 And a colored Map of the United States, after Tanner's ; together vf'Ah. about 
 
 Eleven Hundred Wood-cuts, executed in the best style. 
 
 In leather, gilt, $5 00; library style, $4 50; extra cloth, $4. 
 
 Skinner's Complete Edition of Youatt on the Horse. 
 A BOOK FOR EVERY FARME R A ND COUNTRY GENTLEMAN. 
 
 THE HORSE. By William Youatt. A new edition, with numerous Illui=trations. Toge- 
 ther with a General History of the Horse; a Dissertation on the American Trotting Horse, 
 how Trained and Jockeyed; an account of his remarkable performances; and an Essay on 
 the Ass and the Mule. By J. S. Skinner, Assistant Postmaster-genera), and Editor of the 
 Turf Register. In one octavo volume, of neai'ly 450 large pages, with numerous Illustra- 
 tions; price, in extra cloth, f 1 50; leather, fl 7-S. 
 
78 
 
 BLANCHARD AND LEA'S 
 
 THE BOOK OF NATUKE 
 
 AN ELEMENTARY INTRODUCTION TO THE SCIENCES OF 
 
 PHYSICS, 
 
 ASTRONOMY, 
 
 CHEMISTRY, 
 
 MINERALOGY, 
 
 GEOLOGY, 
 
 BOTANY, 
 
 ZOOLOGY, 
 
 AND 
 
 PHYSIOLOGY. 
 
 . BY FRIEDRICH SCHOEDLER, Ph. D., 
 
 Professor of the Natural Sciences at Worms, &o. &c. 
 First American Edition, with a Glossary and other Additions and Improvements, from the Second English Edition 
 
 TRANSLATED FROM THE SIXTH GERMAN EDITION, 
 
 BY HENRY ME BLOCK, F. C. S., &c. 
 
 
 Profu sel y 
 
 illustrated 
 
 with nearly 
 
 seven hundred 
 
 beautiful 
 
 engravings 
 
 on wood. 
 
 In one large 
 and handsome 
 crown octavo 
 
 volume, 
 of 692 pages, 
 extra cloth ; 
 price fl 80. 
 
 The Geysers of Iceland (Geology). 
 
 To accommodate those who desire to use the separate portions of this work, the publishers 
 have prepared an edition in parts, as follows, which may be had singly, neatly done up in flexi- 
 ble cloth, at 50 ceats each. 
 
 Natural Phllosopliy, 
 
 114 pages, with 149 illustrations. 
 Astrouomy, 64 " " 51 '• 
 
 Chemistry, 110 « " 48 " 
 
 Mineralogy and Geology, 
 
 104 pages, with 167 " 
 
 This volume, as its title shows, covers nearly all the 
 sciences, and embodies a vast amount of information 
 for instruction. No other work that we have seen 
 presents the reader with so wide a range of element- 
 ary knowledge, with so full illustrations, at so cheap 
 a rate. — Silliman's Journal. 
 
 Written with remarkable clearness, and scrupu- 
 lously correct in its details. — Mining Journal. 
 
 His expositions are most lucid. There are few who 
 will not follow him with pleasure as well as with pro- 
 fit through his masterly exposition of the principles 
 and primary laws of science. It should certainly be 
 made a class-book in schools. — Critic. 
 
 Botany, 
 
 98 pages, with 176 illustrations. 
 
 Zoology and Pbyslology, 
 
 106 pages, with 84 " 
 
 Introduction, Glossary, Index, ^c., 
 
 Composed by the same distinguished author, all the 
 departments have a uniformity of style and illustra- 
 tion which harmoniously link the entire circle to- 
 gether. The utility of such a connected view of the 
 physical sciences, and on such an approved basis, is 
 beyond price ; and places their acquisition within the 
 reach of a vastly increased number of inquirers. Not 
 only to such is it valuable, but to those who wish to 
 have at hand the means of refreshing their memories 
 and enlarging their views upou their favorite studies. 
 Of such a book we speak cordially, and would speak 
 more at length, if space permitted. — Southern Metlio- 
 dist Quarterly Review. 
 
 THE DOa. 
 
 By WILLIAM YOUATT. 
 
 Edited, with Additions, by E. J. LEWIS, M. D. 
 
 WITH NUMEROUS PLATES AND WOOD-GUTS. 
 
 In one very handsome volume, crown octavo, done up in beautiful crimson cloth, gilt stamps, $1 25. 
 
MEDICAL AND SCIENTIFIC PUBLICATIONS. 
 
 79 
 
 PRINCIPLES OF THE 
 
 MECHANICS OF MACHINERY AND ENGINEERING. 
 
 BY PROFESSOR JULIUS WEISBACH. 
 
 Translated and Edited by PROFESSOR GORDON, or Glasgow. 
 
 Jtrst American ^bition, iaitlj ^bititions, 
 
 BY PROFESSOR WALTER R. JOHNSON. 
 
 In tivo very handsome octavo volumes, of nearly 900 pages, with about 900 superb Jlhistraiions, 
 handsomely and strongly bound in extra cloth, $6 50. 
 
 Overshot Water- Wheel. 
 
 These volumes contain an immense amount of practical information necessary to the ma- 
 chinist, architect, and civil engineer ; the whole thoroughly brought up to the most advanced 
 state of scientific investigation. The following rapid summary of the contents will show the 
 manner in which the subjects are successively brought forward. 
 
 Volume H. 
 
 Section I. Application of Mechanics in Build- 
 
 Volume I. 
 
 Sect. I. Mathematical Science of Motion. 
 Sect. II. Mechanics in the Physical Science of 
 
 Motion in general. 
 Sect. III. Statics of Rigid Bodies. 
 Sect. IV. Dynamics of Rigid Bodies. 
 Sect. V. Statics of Fluid Bodies. 
 Sect. VI. Dynamics of Fluid Bodies. 
 
 Division II. Application of Mechanics to Ma- 
 chinery. 
 
 Section II. Of Moving Powers and their Ef- 
 fects. 
 
 These subjects, treated in all their ramifications and practical applications to Machines, 
 Water-powers, Dams, Bridges, Water-wheels, Turbines, Roofs, Walls, Arches, Windmills, 
 Scales, Steam-boilers, Water-engines, &c. &c., present points of primary importance to every 
 one engaged in machine-work of every description, building, or engineering ; while the compre- 
 hension of the whole is greatly facilitated by the profusion of clear and beautifully executed 
 illustrations which are interspersed throughout the work. 
 
 THE YOUNG MILLWRIGHT, 
 
 AND MILLER'S GUIDE. Illustrated by twenty-eight Descriptive Plates. By Oliver Evans, 
 with Additions and Corrections by Thomas P. Jones. With a Description of an Improved 
 Merchant Flour-mill, by C. and O. Evans. Fourteenth edition. In one handsome octavo 
 volume, strongly bound in leather, $2 50. 
 
BLANCHARD AND LEA'S PUBLICATIONS. 
 
 New and much Improved Edition — (Lately Issued.) 
 
 PHYSICAL GEOGRAPHY. 
 
 BY MARY SOMERVILLE. 
 
 A NEW AMERICAN, FROM THE THIRD AND REVISED LONDON EDITION. 
 WITH NOTES AND A GLOSSARY, 
 
 BY W. S. W. RUSCHENBERGER, M. D., U. S. Navy. 
 
 In one large royal llmo. volume, of nearly 600 pages, extra cloth, $1 2b; half hound 
 in leather, $1 36. 
 
 Eulog-y is unnecessary with regard to a work like the present, which has passed through 
 three editions on each side of the Atlantic within the space of a few years. The publishers 
 therefore only consider it necessary to stale that the last London edition received a thorough 
 revision at the hands of the author, who introduced whatever improvements and corrections 
 the advance of science rendered desirable, and that the present issue, in addition to this, has had 
 a careful examination on the part of the editor, to adapt it more specially to this country. Great 
 care has been exercised in both the text and the glossary to obtain the accuracy so essential to 
 a work of this nature, and in its present improved and enlarged state, with no corresponding in- 
 crease of price, it is confidently presented as in every way worthy a continuance of the striking 
 favor with which it has been everywhere received. 
 
 From Lieutenatjt Maury, U. S. iV. 
 
 National Observatory, Washington. 
 I thank you for the " Physical Geography ;" it is 
 capital. I have been reading it, and like it so much 
 that I have made it a school-book for my children, 
 whom I am teaching. There is, in my opinion, no 
 ■work upon that interesting subject on which it treats — 
 Physical Geography — that would make a better text- 
 book in our schools and colleges. I hope it will be 
 adopted as such generally, for you have Americanized 
 it and improved it in other respects. 
 
 From Samuel H. Taylor, Esq., Philips Academy, 
 
 Andcnxr, Mass., Feb. 15, 1854. 
 We have introduced your edition of Mrs. Somer- 
 ville's '■ Physical Geography" into our school, and 
 tind it an admirable work. 
 
 From Thomas Shermin, High School, Boston. 
 T hold it in the highest estimation, and am confident 
 that it will prove a very efiScient aid in the education 
 of the young, and a source of much interest and in- 
 struction to the adult reader. 
 
 THE ENCYCLOPEDIA AMERICANA. 
 
 A POPULAR DICTIONARY OF 
 
 Arts, Sciences, Literature, History, Politics, Biography; 
 
 INCLUDING 
 
 A COPIOUS COLLECTION OF ORIGINAL ARTICLES IN AMERICAN BIOGRAPHY. 
 
 ON THE BASIS OF THE SEVENTH EDH ION OF THE GERMAN 
 
 CONVERSATIONS-LEXICON. 
 
 Edited by FRANCIS LIEBER, 
 
 Assisted by E. WIGGLESWORTH and T. G. BRADFORD. 
 
 With Additions by Pkofessor HENRY VETHAKE, 
 
 Of the University of Pennsylvania. 
 
 In fourteen large octavo volumes, containing in all nearly nine thousand large double-columned 
 
 pages, furnished in various styles of binding, at very low prices. 
 
 THE GEOLOGICAL OBSERVER. 
 
 BY 
 
 SIR HENRY T. DE LA BECHE, 
 
 C. B., l\ R. S., 
 
 Director-General of the Geological 
 
 Survey of the United Kingdom. 
 
 WITH 
 OVER THREE HUNDRED 
 
 In one very large and handsome 
 
 octavo volume, of 700 pages, 
 
 extra cloth, $4 00. 
 
If 
 
 '•^ 
 
'% 
 
 \< -K 
 
 .,r«.- ■;»"'■;);, r.'.'WJi, 
 
 '?fjW-» 
 
 ^^t^ Si