a)LUMBIA UNIVERSITY DF.PARTMENT OF PHYSIOLOGY THE JOHN G. CURTIS LIBRARY THE ELEMENTS OF Physiological & Pathological CHEMISTEY A HAyDBOOK for MEDICAL STUDENTS and PBACTITIOXEES CONTAINING A GKNEHAL ACCOCKT OF NUTRITION, FOODS AND DIGESTION, AND THE CHEMISTRY OF THE TISSUES, ORGANS, SECRETIONS AND EXCRETIONS OF THE BODY IN HEALTH AND IN DISEASE TOGKTHER WITH THE METHODS FOR PREPARING OR SEPARATING THEIK CHIEF CONSTITrENTS, AS ALSO FOR THEIR EXAMINATION IN DETAIL, AND AN OUTLINE SYLLABUS OF A PRACTICAL COURSE OF INSTRUCTION' FOR STUDENTS BY T. CEANSTOUN CHAELES, M.D. FELLOW OF THE CHEMICAL SOCIETY AND OP THE ROYAL MEDICAL AND CHIRUKGICAL AND PATHOLOGICAL SOCIETIES ; WASTER OF SURGERY ETC. ; LECTURER ON PRACTICAL rHVSIOLOGY, SX THOMAS'S HOSPITAL ; LATE »IEDICAL KEGISTHAR, ST THOMAS'S HOSPITAL ; AND FOP.MEIiLY ASSISTANT PROFFASOR OF CHEMISTKY AND DEMONSTRATOR OF CHEMISTRY AND CHEMICAL PHYSICS, QUEEN'S COLLEGE, BELFAST ; DEMONSTRATOR OF PHYSIOLOGY AND PHYSIOLOGICAL CHEMISTRY, ST THOMAS'S HOSPITAL MEDICAL school; ETC. ILLUSTRATED WITH 38 ENGRAVINGS ON WOOD AND A CHROMOLITHOGRAPH LONDON SMITH, ELDER, .t CO., 15 WATEHI.OO PLACE 1884 [All riglilx rexf rrci/] n OC Digitized by tine Internet Archive in 2010 witii funding from Open Knowledge Commons http://www.archive.org/details/elementsofphysioOOchar DEDICATED WITH EVERY FEELING OF ADMIRATIOX AND FRIENDSHIP TO TWO OF THE AUTHOR'S FORMER TEACHERS D« FELIX HOPPE SEYLEE the clUliii'jui.'Jiid Professor of Physiological C'ltemislry in llf UnirersiiH of Slrassbiuy WnO-E NAME IS SO OFTEN QUOTED IN THE FOLLOWING FACES AND D" JOHN SYEK BRISTOWE, F.E.S., LL.D., F.R.C.P. Senior Physician and Levturer on M-dieine at Si Thomas's lioipilal FROM WHOM HE HAS RECEIVED SOME OF HIS BE«T LESSONS IN MEDICINE PEEFACE. It is unnecessary at the present clay to insist upon the import- ance of a knowledge of chemistry, and particularly of physio- logical and pathological chemistry, to the student of medicine ; but it must always be carefully borne in mind that just as the proper study of pathology requires a previous knowledge of histology and physiology, so the study of physiological chemistry should be founded on a well-grounded and extensive acquaint- ance with the principles of general chemistry. Not, indeed, until a close connection was established between chemistry and medicine did any decided advance occur in the latter ; and by its means the medicine of the future will undoubtedly be still further enlightened and extended. Physiological chemistry promises much even in the treatment of disease ; for it is beginning to be seen, from the investigation of the molecular constitution of different bodies, that there exists a distinct connection between their specific atomic grouping and their physiological action. And even in some of the most interesting investigations of the pathology of the present day — those con- nected particularly with the causation of infectious diseases — ■ physiological chemistry will, without a doubt, take a most prominent place ; for there is every reason to believe that the micro-organisms which play so important a part in these diseases really act by virtue of a ferment-working virus or zymosis of some kind which accompanies them or is generated by them. The hope may therefore be expressed that the viii PREFACE. further investigation of the chemical properties of these micro- zymes and their respective zymoses will shortly lead to a closer acquaintance with their mode of action, as well as to a know- ledge of how to stamp them out or to thwart their activity. And either to understand them or to be able effectually to counteract their virulence will demand a great increase upon our present knowledge of the chemistry of the body both in health and disease. In the following pages an attempt has been made to present the medical student and practitioner with an outline of the most important branches of physiological chemistry ; but to render the work more complete, both for private study and for laboratory purposes, I have been compelled to introduce brief descriptions of such bodies as sugars, fats, and certain salts, &c., which are more appro j)riately treated of in works upon general chemistry. I have treated my subject under four main heads : — Book I. Nutrition and Foods. „ II. Digestion and the Secretions concerned. „ III. 27ie Chemistry 0/ the 2'issues, Organs, and liernaining Secretions. ,, TV. 2'he Excreta : the Fo'ces and Urine. Every effort has been made to retider the work as practical as possible. I have accordingly confined myself chiefly to those parts of the subject which bear most directly upon ]>ractical medicine; and I feel sure that, by following the indications laid down throughout the book, effectual assistance will often be given to the physician in establishing the diagnosis as well as the etiology of many of the complicated diseases he may be called upon to treat or investigate. Temperatm'es have, with a few exceptions, been stated in centigrade degrees. A choice of methods and processes has generally been given, particularly when there is any difficulty to be overcome; and, when the importance of the subject rREFACE. ix merited it, not only the methods Init also the theories of different authorities have been detailed. Discussions of unsettled questions have as much as possible been avoided ; and, keeping steadily in view the object for which the book is intended, the author has been compelled, and often reluctantly, to omit many subjects and details that in themselves are highly interesting and instructive, but which he deemed beyond the limits of the present treatise. Despite his wishes, however, the book has far outgrown his original intentions. The urine, as being from a physiological as also a patho- logical point of view one of the most important excretions of the organism — many of its indications being of the most precious and valuable kind to the physician and surgeon both in diagnosis and treatment — has therefore been treated with considerable detail. Some of the most approved methods for the examination of this fluid have been given, and, as far as possible, all its indications that possess a diagnostic value have been referred to, with a view to establishing as rational a line of treatment as possible. In the syllabus with which the book concludes a course of procedure is indicated which may be pursued with great advantage by the student ; but of course the amount of work to be done will largely depend upon the time at his disposal. Unless, however, this is very limited, it would be greatly to his benefit to go through the scheme I have laid down, omitting possibly a few of the modes of preparation in some of the sections. By means of demonstrations also it would be possible to lighten his labours considerably ; and only in this way, it seems to me, will the student be able to grapple successfully with the task before him. But it must be confessed that it is far too commonly the case for students to begin the study of physiological chemistry before having attained any accurate acquaintance with general chemistry. This is greatly to be deplored, for under such circumstances they cannot derive X PREFACE. the benefit they otherwise would be sure to gain. Not only should the student have a thorough knowledge of the elements of general chemistry, but it would also favour his progress greatly if, in addition to the oi'dinary practical course of qualitative analysis generally pursued, he performed a few simple quantita- tive analyses. The names of authorities have, as a general rule, been quoted, but references have been entirely omitted, as it was found that the space which would have thus been occupied would have been much too considerable in a mere manual like the present ; but while, as far as I possibly could, I have- acknowledged in the brackets throughout the book the very numerous authorities responsible for the facts or theories stated, yet I feel that I should at least mention here the works to which I have been particularly indebted, viz. Hoppe Seylee's ' Physiologische Chemie ' and 'Handbuch d. Physiol ogisch- und Pathologisch-Chemischen Analyse,' Hermann's 'Handbuch d. Physiologie,' Hofmann's ' Lehrbuch d. Zoochemie,' Kuhne's Physiologische Chemie ' and ' Untersuchungen aus d. Physio- logischen Institute d. Univ. Heidelberg,' Salkowski and Leube's ' Die Lehre vom Ham,' Liebeemann's ' Chemie d. Menschen,' Pflugee's 'Archiv f. Physiologie,' GtAUTIEe's ' Chemie appliquee a la Physiologie,' Pavy's ' Food and Dietetics,' Smith's ' Foods,' Foster's ' Physiology,' and Watt's ' Dictionary of Chemistry.' Ciioi TON Lodge, Streatham, London, S.W. March 1884. CONTENTS. BOOK I. NUTRITION AND FOODS. CHAPTER I. APPAKATIS AND CHEMICALS. P.VliK Preparation of some of the reagents . . . . . .1 CHAPTER n. METHODS AND PROCESSES. Dialysis — Decantation — Desiccation — Distillation — Evaporation — Filtra- tion — Incineration — Preparation of normal solutions— Specific gravity 5 CHAPTER III. NUTRITION. Assimilation — Digestion— Energy — Nutritive powers of the tissues — Necessity for constant supply of oxygen . , . .13 CHAPTER IV. FOODS. Definition of a food- -Elements necessary — Dynamic value — Maintenance of equilibrium betvireen ingesta and egesta — Proportion of the chief tissues of the body — Water and salts of the body — Mixed diet — Classi- fication of foods . . . . . . . .17 CHAPTER V. THE NITROGENOUS FOODS. Animal albumins : meat, bacon, fish, oysters, eggs, milk, cheese — Vege- tuhle albumins : grains and seeds, bread and biscuit, fruits, cabbages, mushrooms, tea, coffee — Classification of vegetables and fruits . 2.5 xii foxn-jyTs. CHAPTEK VI. FATS AND CARBOIIYDRATJiS, ETC. /iV/^' of alcolml — Minerals in the fond — baits of importanc'e . . ;i() CHAPTER VI r. STARVATION. Elfect on tLssue waste — Wasting diarrhoea . . . . 3.S CHAPTER VHI. CHE.MISTRY OF THE ALCOllOL.S A.\D FATTY ACIDS, ETC. Etliyl alcohol — Glycerin — Acids— The acetic acid series: formic, acetic, prcpiunic, butyric, valerianic, caproic, palmitic, stearic, lactic, oxalic, succinic, oleic, and carbolic acids . . . . .34 CHAPTER IX. CHEMISTRY OF THE CARBOHYDRATES. Glucoses, saccharoses, and amyloses — Starch and dextrin . . -44 CHAPTER X. GLYCOGEN. Preparation— Properties — Sources — Destination — Conversion into sugar — Experiments — Tests and reactions . . . . .49 CHAPTER XL CANE SUGAR, DACTOSE, AND MALTOSE Lactose: properties, preparation, and detection— ^Arabin and arabinose . 57 CHAPTER Xll. GRAPE SUGAR OR DEXTROSE. Properties— Preparation — Combinations — Decompositions — Urigin — Ji'u/r — Destination — Tests . . .... 60 CHAPTER XIII. QUANTITATIVE DETERMINATION OF GRAPE SUGAR. ]\y )xjlarisation — Explanation of the process — Saccharimetry and saccha- rimetcrs — Fbhling'.s mri/tod hy a standard copper golutivn — Knapp's mercuric cyanide method — SACiit-SE's viethod — The fermentation j)ro- rcfn — Roberts's diJTerential doi^iti/ wrthnd — Methods of Vogel, Garkod, and .Johnson . . . . . . ,70 COXTEXTS. xiii CHAPTER XIV. INOSIT. Preparation — Properties — Tests . . . . . .81 CHAPTER XV. FATS. Constitution— Paltnitin -Stearin -Oluiii — -Origin and source of the fats in the organism — -Destination and distribution of fat in the body — Tests for the presence of fats or fatty acids — Detection of fat in a mixture — Determination and separation of fat . . . .S3 CHAPTER XVI. PKOTEIDS OR ALBUMINOIDS. Wiicre found — General characters — Composition, constitution, and for- mulas—Combinations, derivatives, origin, and destination — Theories as to the terminal products of the decomposition of albumin . . 89 CHAPTER XVII. THE Pl{OTEIN REACTIONS AND ALBUMIN TESTS. Preparation of an albumin solution for testing — Differences between egg and serum albumin — General tests and reactions — Alteration of albu- min by the action of acids and alkalies — The formation of albuminates — Detection of albumin in an animal fluid, and its separation from its solutions . . . , . . . . . !)(} CHAPTER XVIII. CLASSIFICATION OF ALBUMINS. Xative albumins : serine, white of egg — Composition of a hen's egg — Glohulins : vitellin, crystallin or globulin, myosin — To prepare muscle plasma — Muscle juice and serum, syntonin, fibrinogen, fibrinoplastin — Preparation of these bodies and of blood ferment — Plasmin of Denis — Generation of fibrin — Fibrin, its preparation — Albuminates : alkali albumin, casein, acid albuminate, syntonin or albumose — Pejrtoncs : preparation and properties — Amyloid substance, or lai'daccin, its tests and mode of extraction — Coagulated albumin, metalbumin, and parah bumin ......... 103 CHAPTER XIX. TABLE IDENTIFYING THE CHIEF ALBUMINS . . . .125 CIIArTER XX. THE COLLAC4ENS, rAr:K Their percentage composition — Gelatin— CoWiigen — Chnndrin— Mucin— Gelatin, chondrin, and mucin compared — Elasticin or ciaatiw . . 127 CHAPTER XXI. LEUCIN AND TYROSIX. rrcparation -Properties— Tests ...... liJ-) BOOK II. DIGESTION AND THE SECRETIONS CONCERNED. CHAPTER I. ferments; fermentation; and DECOMPCSITION, or rUTREFACTION. Division of ferments — Classification of fermentation processes — Lactic acid, alcoholic, acetous, and mucou? fermentations — Histozym, mi- crozyma-s, and schizomycetes — Contagium, antiseptics, and disinfect- ants . . . ■ • • • . - lil CHAPTER II. DIGESTION. Nature of the process as occurring in the mouth, stomach, and intestines The chyme, chyle, and peptones — The digestive action of different juices Amount of fluids discharged into the alimentary canal . 14i) CHAPTER III. PREPARATION OF THE JUICES. Saliva— Gastric juice— To prepare hydrochloric acid of the proper strength for artificial digestion — Pancreatic juice — Intestinal juice — Bile . 154 CHAPTER IV. THE DIGESTIVE FERMENTS. Diastase — Preparation of ptyalin, pejjsin, and of the pancreatic and liver ferments ......... 157 COXTEXTS. XX CHAPTER V. DIGESTION METHODS AND EXPEKIME.N TS. PAGK Conversion of starch into sugar, of albumin into peptones, and pro- perties and decompositions of the latter — Digestion of fats . . 163 CHAPTER VI. CHEMISTRY OF THE DIGESTIVE SECRETIONS. The salivd : composition ; secretion, and stimuli thereto — Quantitj', func- tions, reactions, pathology, and determination of its sulphocjanide . 169 CHAPTER VII. GASTRIC JUICE. Siiccus 2>ylorlcus. Composition, quantity, digestive action, and theories as to the nature thereof — Histological changes in the secreting cells of the stomach and pancreas as the result of their activity — Condi- tions affecting the digestive phenomena— Pathological changes in the juice . . . . . . . . .177 CHAPTER VIII. PANCREATIC JUICE. Quantity — Secretion — Chemical constituents — Ferments — Zymogen — Digestive actions of the juice— Differences between peptic and tryptic digestion — Pathological alterations ..... 188 CHAPTER IX. INTESTINAL JUICE. Quantity and actions — Secretion of the large intestine . . . 191 CHAPTER X. THE BILE. Physical properties — Absorption spectrum — Amount — Secretion — Chemical composition — Effect of food on constituents — Actions — Role of bile in the econom}' — Source and production of the biliary acids and pig- ments — Tests and reactions — Separation of the biliary constituents — Pathological alterations and biliary calculi . . .196 CHAPTER XI. THE BILIARY ACIDS. Preparation — Properties — Tests — Derivatives: choUc or cholalic acid, gly- eocin, and taurin ........ 206 a xvi CONTENTS. CHAPTER XII. THE BILIARY PIGMENTS. PAGE BiUrithin : preparation, properties, derivatives, and cliaracteristics— JlydroUlirnhin or stercoMlin — Btlive^'din — Eelatlons among t he soluble pigments of the body . . . . . . .212 CHAPTER XIII. CHOLESTERIN, Preparation— Properties— Tests— Characteristics .... 216. BOOK III. THE TISSUES: CHEMISTRY OF THE TISSUES, ORGANS, AND REMAINING SECRETIONS. CHAPTER I. THE BLOOD. Functions — Physical characters — Quantity — Distribution — Microscopic constituents — Chemical composition — The corpuscles, the plasma, the serum, and the gases of the blood — Changes in the blood gases in re- spiration — How the constitution of the blood is affected — Arterial and venous blood — Portal and hepatic blood — Splenic and placental blood — Influence of sex, age, and food . . . .219 CHAPTER II. HEMOGLOBIN. Preparation — Properties — Crystals — Absorption spectra — Derivatives - Proportion of haemoglobin present In blood — Tests . , . 233 CHAPTER III. ESTIMATION OF HiEMOGLOBlN. The volumetric colour method— Methods of HoppE Seylbr and GowERS — Determination by the Spectroscope— Pathology . . .212 CHAPTER IV. HiEMATIN. rrepatition — Derivatives -Absorption apccira,— IJ'fmtitoidi ». . , '2iC> CONTENTS. xvii (HIAPTER V. TACE Preparation — Tests ........ 24S CHAPTER VI. COAGULATION OF THE BLOOD. Theories as to the causes — Fibrin ...... 250 CHAPTER VII. METHODS AND PRACTICAL EXERCISES FOR THE SEPARATION, PREPARA- TION, OR IDENTIFICATION OF DIFFERENT BLOOD CONSTITUENTS. Albumin and the salts of the serum — Lecithin — Fats and cholesterin — Separation of the corpuscles — Experiments with plasma — Preparation of fibrinoplastin, fibrinogen, blood ferment, and fibrin clot — Detection of ammonia — Nessler's solution ..... 2o4 CHAPTER VIII. TESTS AND CHARACTERISTICS OF BLOOD. Chemical tests — Practical exercises with the spectroscope — Detection of blood in spots, stains, &c. ....... 257 CHAPTER IX. ESTIMATION OF SINGLE CONSTITUENTS OF BLOOD. Water and ash — Soluble and insoluble salts and chlorides — Fibrin — Fats — Albumins — The Corpuscles : plans of Malassez and Gowers — Urea, uric acid, and sugar ...... 263 CHAPTER X. PATHOLOGY OF THE BLOOD. Types of variations — The blood under pathological conditions — Altera- tions produced by certain toxic and other agents, htemorrhage, &:c. — Table showing the alterations in the blood in different diseases . 269 CHAPTER XI. LYMPH AND CHYLE. Amount — Physical properties — Chemical composition — Practical metliods for examination ........ 273 a 2 xviii CONTENTS. OIIA.PTER XII. SEROSITIES AND TRANSUDATIONS. PAGK Physiological, as cerebro-spinal and pericardial fluids, aqueous humour and synovia — Pathological : as fluid of anasarca, ascites, ovarian, strumous, or echinococcus cysts, pleuritic fluid, and fluid of intestinal fluxes — Transudations in albuminuria— Table of analyses of different serous transudations ....... 278 CHAPTER XIII. PUS AND MUCUS. Analyses — Pus corpuscles, their protojflasm — Nuclein — Abnormal consti- tuents — Properties and composition of mucin .... 283 CHAPTER XIV. METHODS FOR THE EXAMINATION OF SEROUS FLUIDS. Qualitative analysis for some of the constituents of a serous liquid — Detailed examination of a serous liquid ..... 289 CHAPTER XV. EPITHELIAL STRUCTURES. Epitheliums — Keratin — Hairs — Horny structures— Crystalline lens . 292 CHAPTER XVI. CONNECTIVE TISSUES. Structural elements : cells, fibres, and cement — Classification— Chemical composition ........ 297 CHAPTER XVII. CARTILAGE. Classification of cartilages — Chemical characters and composition . . 300 CHAPTER XVIII. BONE. General constitution considered histologically — Chemical composition — The marrow — Practical exercises and methods — Quantitative analysis . ?03 CHAPTER XIX. TEETH. The cement, dentine, and enamel . . . . . .311 CONTENTS. xix CHAPTER XX. MUSCLE. I'AOE Properties — Changes occurring in muscle during activity, rigor, and death — Chemical composition — Nitrogenous constituents and extractives : hreatin, sarkosin, sarkin or hypoxanthiti, xanthin, carnin, giianin, &c. — Non-nitrogenous constituents : iiwsit, glycogen, fats, paralactic acid — Inorganic constituents, as water and salts — Pathology — Sources of muscular energy — General analytical methods: preparation of watery extract ; separation of the soluble albumins ; precipitation of phosphoric, sulphuric, and uric acids, of hypoxanthin, and of the kreatin and gelatin in part — Separation of the extractives after Stadeler — Analysis of LlEBlG's extract of meat . , . . . . .313 CHAPTER XXI. NER>-E. Histological constitution — Grey and white matter — Chemical composition : the chief constituents and the ultimate analysis —Lecithin : prepara- tion, characters, relations, and properties — Protagon: preparation, relations, and characters — Eephalins and myelins— Becomposition jtro- ducts : glycerin phosphoric acid ; nenrin, preparation and properties ; cerebral fats, and cholesterin — Cerebrin : preparation, properties, com- position, and formula — Neuro-keratin — Phrenosin — Thudichum's method for isolating and separating the brain constituents — Sonnen- SCHEIN's method for isolating alkaloidal principles , . . 330 CHAPTER XXn. THE EYE. Retina : rods, cbromophane, vision purple, pigment — Aqneous huviour — Tears — Cornea ........ 344 CHAPTER XXIII. THE SKIN. The stveat, its amount and composition — Melanin — Sebaceous secretion — Pathological alterations of skin ...... 348 CHAPTER XXIV. THE LIVER. Chemical composition and pathology ..... 353 CHAPTER XXV. THE PANCREAS. Constituents ......... 356 XX CONTENTS. CHAPTER XXVI. THE SPLEEN. PAGE Clicmical composition and pathological alterations .... 356 CHAPTER XXVII. SUPEAKENAL CAPSULES, THYMUS, THYROID, LYMPHATIC GLANDS, AND KIDNEYS ....... 358 CHAPTER XXVIII. THE LUNGS. Composition and pathological alterations in tubercle, &;c. — Concretions and sputa ......... 362 CHAPTER XXIX. RESPIRATION. Changes effected upon the air when respired — Quantity of air, carbonic anhydride, and water inspired and expired — Circumstances affecting the respiratory exchanges, particularly with reference to the carbonic anhydride : rest or activity, food, hunger, period of day, h'ght or dark- ness, sleep or wakefulness, sex, age, mode of respiration, state of the circulation, cerebral activity or repose, season and temperature, altera- tions of pressure, species, and disease — Variations in the respired air . 365 CHAPTER XXX. PROSTATE, TESTICLE, OVARY, AND SEMEN. Naclein, protamin, spermatozoa, spermatiu, ovarian cysts — Paralbumin — ErCHWALD's colloid ....... 375 CHAPTER XXXI. DEGENERATIONS. Fatty — Colloidal — Mucous — Amyloid — Pigmentary — Calcareous . . 379 CHAPTER XXXII. MILK. Physical characters — Uterine milk — Chemical composition — Casein — Coa- gulation of milk — Rennet — Alterations in milk produced by exposure to the air, age of the animal, duration of the secretion, food, rest, &c. — i?Mffcr— Preservation of milk — Substitutes for woman's milk — Patho- logical alterations in milk ...... 381 CONTENTS. xxi CHAPTER XXXIII. THE ANALYSIS OF MILK. PAGE Physical characters — Tests: qualitative and quantitative— Determination of the solids, butter, casein and albumin, and the sugar . . 394 BOOK IV. EXCRETA : THE FuECES AND UKINE. CHAPTER I. THE FiECES. Chemical composition — The gases of the intestine — Indol — Shatol — Excretin — Pathological alterations of the faeces— Intestinal concre- tions — Scybalis ........ 400 CHAPTER II. THE URINE. General characters — Reaction — To estimate the acidity— Colour, trans- parency, quantity — Specitic gravity : how to take it, and to obtain the percentage of solids and ash — Odour ..... 406 CHAPTER HI. CONSTITUENTS OP URINE. Organic and inorganic^ — Table showing the constituents of the normal urine, and of the amounts of them discharged in the twenty-four hours in health and in disease — The gases in urine and the amount of solids . 413 CHAPTER IV. REACTIONS AND CHARACTERISTICS OP NORMAL URINE . .418 CHAPTER V. UREA. Preparation — General characters — Chemical relations — Combinations- Decompositions — Reactions and tests - To separate the urea from urine — Detection of vurea in the blood, ifcc. ..... 422 XX CONTENTS. CHAPTER XXVI. THE SPLEEN. PAGE Chemical composition and pathological alterations .... 356 CHAPTER XXVII. SUPRARENAL CAPSULES, THYMUS, THYROID, LYMPHATIC GLANDS, AND KIDNEYS ....... 353 CHAPTER XXVIII. THE LUNGS. Composition and pathological alterations in tubercle, k.c. — Concretions and sputa ......... 362 CHAPTER XXIX. RESPIRATION. Changes effected upon the air when respired — Quantity of air, carbonic anhydride, and water inspired and expired — Circumstances affecting the respiratory exchanges, particularly with reference to the carbonic anhydride : rest or activity, food, hunger, period of day, light or dark- ness, sleep or wakefulness, sex, age, mode of respiration, state of the circulation, cerebral activity or repose, season and temperature, altera- tions of pressure, species, and disease — Variations in the respired air , 365 CHAPTER XXX. PROSTATE, TESTICLE, OVARY, AND SEMEN. Nuclein, protamin, spermatozoa, spermatin, ovarian cysts — Paralbumin — KfCHWALD's colloid ....... 375 CHAPTER XXXI. DEGENERATIONS. Fatt}' — Colloidal — SIucous — Amyloid — Pigmentary — Calcareous . . 379 CHAPTER XXXII. MILK. Physical characters — Uterine milk — Chemical composition — Casein — Coa- gulation of milk — Rennet — Alterations in milk produced by exposure to the air, age of the animal, duration of the secretion, food, rest, &c. — /fu/fcr — Preservation of milk — Substitutes for woman's milk — Patho- logical alterations in milk ...... 381 CONTENTS. xxi CHAPTER XXXIII. THE ANALYSIS OF MILK. PjVGE Physical characters — Tests: qualitative and quantitative— Dctenuiiiation of the solids, butter, casein and albumin, and the sugar . . 3U4 BOOK IV. EXCRETA : THE FuECES AND URINE. CHAPTER I. THE F^CES. Chemical composition — The gases of the intestine — Indol — Sliatol — Excreiin — Pathological alterations of the faeces — Intestinal concre- tions — Scybalas ........ 400 CHAPTER ir. THE URINE. General characters — Reaction — To estimate the acidity — Colour, trans- parency, quantity — Specific gravity : how to take it, and to obtain the percentage of solids and ash— Odour ..... 406 CHAPTER III. CONSTITUENTS OF URINE. Organic and inorganic — Table showing the constituents of the normal urine, and of the amounts of them discharged in the twenty-four hours in health and in disease — The gases in urine and the amount of solids . 415 CHAPTER IV. REACTIONS AND CHARACTERISTICS OF NORMAL URINE . .418 CHAPTER V. UREA. Preparation — General characters — Chemical relations — Combinations- Decompositions — Reactions and tests- -To separate the urea from urine — Detection of urea in the blood, ifcc. . . . . .422 xxii COXTENTS. CHAPTER Vr. SOURCES AND AMOUNT OF UREA, AND INFLUENCES AFFECTING THE LATTER. PAGK Source and seat of formation — Amount excreted, and influences affecting this : constitution, sex, age, weight, character of the food, activity and rest of the brain or body, drugs, and diseased conditions — Umsmia . 428 CHAPTER VII. QUANTITATIVE DETERMINATION OF UREA. Liebig's method : its principle, preparation of the necessary solutions, the process, necessary corrections for excess of urea and for presence of sodic chloride, albumin, ammonia, lencin, tyrosin, &c. — Modifications of the process : Dragendoeff's, Hoppe Seyler's, NEUBAUEEand Voit's, and Pfluger's — Eatimation hy convention of the urea into nitrogen gas: Kxop and Hufnee's method, Russell and West's, Simpson and O'Keefe's— Modifications proposed: DuGGAN, Woemley, &c. — Other methods : EuNSEN's, Will-Vaeeentrap's, Hetntz and Ragsky's, Wanklyn's ........ 434 CHAPTER VIIT. URIC ACID. Where found — Quantity excreted — Preparation — Properties — Combina- tions — Decompositions — Tests and reactions — To determine its presence in urine and its amount : Garrod, Heintz, Ludwig, Petit, &c. — Pathological increase and diminution . . . 448 CHAPTER IX. URATES AND URIC ACID DERIVATIVES. Properties — Occurrence of a deposit of urates — Derivatives : alloxantin, alloxan, iirainil, ^^?(?;/;? 491 xxiv CONTENTS. CHAPTER XVIII. THE SALTS OF THE ALKALIES. PARE To detect the soda and potash, and estimate them — Estimation of the ammonia . . . . . . . . . 501 CHAPTER XIX. ABNORMAL CONSTITUENTS. Albvmi?iovs vrine — Forms of albumin present — Characters of the urine, amount, and tests — To separate the albumins from urine — Quantitative estimation of the albumin : after Scheeer's method, bj'' the polariscope, Esbach's method, clinical method of deposits, Roberts's dilution method, Bodecker's method, and Tanret's method , . . 502 CHAPTER XX. PATHOLOGY OF ALBUMINURIA. The causes and diagnosis thereof ...... 512 CHAPTER XXI. HEMATURIA, OR BLOOD IN THE URINE, Properties of bloody urine — Tests — To distinguish between hsematuria and albuminuria — Pathology — Hemoglobinuria — Methaemoglobin in the urine .......•• 516 CHAPTER XXII. SUGAR IN THE URINE. Presence of sugar in normal urine — Properties of urine containing sugar — Tests — To separate the sugar from urine — Quantitative estimation : by Fehling's method, by the same method as modified by Duhomme, by Johnson's method, and by Bouchardat's density method — Glycosuria and diabetes ; artificial production of the latter— Alkajff on and pyrocatecldii ........ 521 CHAPTER XXIII. BILIARY URINE. The presence and amount of the biliary acids — Properties of biliary urine — Tests for the biliary acids and the biliary pigments — Patliology — Jaundices classified according to their origin .... 530 CONTENTS. XXV CHAPTER XXIV. MUCUS AND PUS ; CHYLURTA. PAGE To detect mucus in urine and determine its amount — Examination of pus in urine — Sources of the pus — Chyhiria and tilarla sanguinis --To separate fatty bodies from urine ...... 536 CHAPTER XXV. ADDITIONAL ABNORMAL URINARY CONSTITUENTS. Excretion by the kidneys of many or^^anic and inorganic substances, and the methods for delecting some of them — Inorganic abnormal consti- tuents : neutral salts of the alkalies, alkaline carbonates, alkaline earths, and salts of the heavy metals — Organic: alcohol, chloroform, organic acids, alkaloids, and aromatic bodies — Methods for detecting : potassic iodide and bromide, lithia, chloroform, iodoform, phenol, salicylic acid, chrysophanic acid, santonin, quinine, morphine, and salts of lead, silver, and mercury ...... 540 CHAPTER XXVI. TABLE FOR THE EXAMINATION OF MORBID URINE . . . 546 CHAPTER XXVII. URINARY SEDIMENTS OR DEPOSITS. Extraneous deposits — Classification of deposits — Characters to be noted — Preliminary examination of a deposit — Cystin: its preparation and separation. &c. — Table showing the different deposits and how to dis- tinguish them — Action of caustic potash on deposit s . . • 5.")2 CHAPTER XXVIII. PHYSIOLOGICAL AND PATHOLOGICAL CONDITIONS IN WHICH DIF- FERENT SEDIMENTS OCCUR ...... 564 CHAPTER XXIX. URINARY CASTS. Source— Classification — Examination of casts- -Pathological occurrence of casts and their significance ...-•• 566 xxvi COXTJRXTS. CIIAPTEll XXX. CALCULI. PAGE Their relative frequency — Different forms, with their general characters — Preliminary examination of a urinary calculus — Examination of a biliarj- calculus — Arrangement of calculi in three classes according to the action of heat upon them — Table for identifying calculi . . .571 CHAPTER XXXI. SYLLABUS OF PEACTICAL COURSE. Hydrocarbons and their examination — Nitrogenous bodies — Albumins and their derivatives — The digestive juices and digestion — Examina- tion of bile and blood, and of the secretions and tissues, as pus, mucus, bone, muscle, and milk — The examination of normal and morbid urine, and of urinary deposits and calculi . . 579 IXDICX . 591 THYSIOLOGICAL AND PATHOLOGICAL CHEMISTRY. BOOK I. NUTRITION AND FOODS. CHAPTER I. APPARATUS AND CHEMICALS. The student should be provided with the following reagents :- Water, rain or distilled Ammonia Alcohol, absolute Caustic potash, in sticks and in methylated spii ■it solution (1 : 2), and (1:8) Etluir Caustic soda Cliloroform Slaked lime " Glycerin Baryta water (1 ; 15) Hydrochloric acid Alum Nitric )> Ammonic oxalate (1 : I'U) Sulphuric 3) „ chloride (1:8) Glacial acetic J> ,, carbonate (ill) Oxalic ., .„ niolybdate '' Chromic 5> Bromine Tartaric ;; (1: •1) „ water (1 : ;5()) Tannic ■>■) (1: 10) Baric chloride (1 : lO) " Slaked Lhiie. — To prcj)are ihUIc of lime place some fi'a"uieiits of recently burnt lime in a capsule, and add a little water, stii'rini,' the mass with a glass rod. A fine powder will be obtained, when more water is to be added until a milky-looking fluid is obtained, which is to be filtered through some muslin. '' Mohjbdate of Ammonia. — Dissolve 4 grams in a little am- monia, and then add about 60 c.c. nitric acid ; lay aside for some time, decant, and make up to 100 c.c. with water. B NUTRITION AND FOODS. Baric nitrate (1 I 12) ,, „ (saturated) Bismuthic nitiate Calcic chloride (i I 5) „ carbonate Chloride of lime Copper sulphate (1 : 12) Chlorine water "^ Iodine, tincture „ solution (5 grains shaken np with 1 oz. water)'' Indigo solution Iron sulphate (1:4) ,, sulphide Litmus solution « Liquor ferri perch loridi (1 : 10) Lead acetate (1:8) (neutral and basic) Magnesic sulphate (1:6) ,, „ (saturated) Masrnesia mixture '^ Mercurous chloride (cjilomel) Mei-curic „ (1 : 16) ,, nitrate Millon's reagent*' Magenta Platinic chloride (1 : 10) Potassic chromate (1 : 20) „ nitrate (free from chloride) ,, sulphocyanide ,, ferrocyanide (1 „ ferricyanide (1 iodide (1 : 20) Eosolic acid (1 : 100 alcohol) Starch solution'' Sodic acetate ,, carbonate (saturated and 1 : 8) ,, chloride (saturated) ,, phosphate (saturated and 1 : 20) 12) 12) '^ Chlorine Water. — Prepare chlorine gas by griilly warming some black oxide of manganese with strong sulphuiic acid in a small retort, and pass the gas into water to saturation. Or heat the following mixture : sodic chloride 18, black man- ganic oxide 15, sulphuric acid 45, and water 15. '' Solulion of Iodine. — Dissolve 2 parts potassic iodide in 100 parts water, and then add 1 part iodine and shake well. '' Litmus Solution. — Place 10 grams litmus cake in 4 litie distilled water, leave it to digest in a warm place for 3 or 4 hours, and then decant the clear licjuid fiom the sediment. To half of it add a few drops very dilute sulphuric acid until a faint reddish or violet tinf^e is obtained ; and to the othci-half a very little dilute alkali until it becomes blue. J' McKjiiesia Mixture. — Crystallised sulpliatc of magnesia 1, am- monium chloride 2, ammonia 4, water 8. Mix well together. ^ 3Iillon'.s lico/jcnt. — 1 part mercury is treated with 2 j)arts nitric acid (sp. gr. L4) in the cold, and then over a water bath till completely dissolved ; it is to be diluted with 2 parts water, and the clear li(]uid decanted after 3 or 4 hours. ^ Starch Solution. — Ifub 1 part starch with 8 parts cold water in a mortar ; then pour the mixture slowly into 40 parts boiling water. A ri'A RA T US A XD CHE MI CA LS. Sodic siilphiite (satuniicd) ,, nitropiusside ,, liypochlorite Silver nitrate (1 : 30) Sulphuretted hydrogen and ainmoniuoi sulphide' Tin protochloride Zinc chloride ' Suljihinrtted Ifydroyen. — Pivpixre this when requi-ed, usin<^ a large wide-mouthed hottle half filled with dilute sulphuric acid. The cork of this l)ottle is pierced Ijy two holes, through one of which passes tightly a strong glass rod hooked upwards at its lower end. This hook supports a small porcelain dish ])ierced with holes, and in which fragments of ferric sul])hide are placed. The other hole in the cork contains the tube for the escape of the gas, and to this is fitted a wide drying tube tilled with cotton. When the gas is needed, lower the ferric sulphide into the acid by l»ushiug down the supporting rod ; by raising it again the evolution of gas ceases. It is ad- visable to wash the gas by passing it through a little water. Ainiiiunic Sidjihiilt'. — Prepare this by satu- rating, say, 60 c.c. li(jnor ammonise with hydric sulphide gas, and adding to it 40 c.c. more of the liquor ammonia'. Of APPARATUS it is well to be provided with the followino; : — Fig. 1. — SuLPiiunETTKD HyiJUOGKS Al"I'AK4TUS. (I, large bottle contaiuiiig dilute suli)liuric acid ; ft, a glaps rod that can he luoveil u]) and down in the cork stopping tlie bottle, and supporting a small porcelain cu]) jiierced with holes and filled with ferric sul- phide ; c a drying tube tilled with cotton. Test tubes ( 1 2) Test-tube rack with draining pegs Small funnels (^ oz., 1! uz., 4 oz., 8 oz., 10 oz.) Small tube funnels (tlass rods ,, tubing of dill'erent dia- meters Wash bottle (water) „ (spirit) Two or three nests of beakers Fla.sks of different sizes, in- cludinsr Florence flasks Porcelain evaporating dishes Small conical glasses Watch glasses Water bath Sand bath Spirit lamp Bunsen lamp Kose or ring burner Blowpipe Three-cornered and rat-tailed files Cork-borers Spatulas — one of platinum Crucible tongs Wire triangles B 2 NUTRITION AXI) FOODS. Eetort stands provided with rings of different sizes Pincers Forceps AVoulfs bottles Wedgwood mortar (1 pint) Small mortar Platinum foil wire Small porcelain crucibles „ distillation apparatus An air batli Thermometer indicating up to 150° An ordinary balance A chemical balance Indiarubber tubing Sheet indiarubber A microscope A polarisco[)C Slides and cover glasses Urinonieter Pipettes Graduated pipettes Glass measures A set of Mohr's bui-ettes Filteiing paper Blue and red litmus paper Litmus solution and cake Slips of paper prepai'ed with acetate of lead, turmeric, and ammonium molybdate Fii;. 2.— Mijiiii's BuitK'iTKs and Pii'K'rriC!^. a witli K piiicli cock, b with a piece of glass rorl in w;rt<-odit'S that pass thus readily through or penetrate membranes or gelatinoxis masses are calh'd crystalloids, while those not possessing the property are named culloids (Graham). But it must be remem- bered that all bodies that crystallise (such as haemoglobin) do not dialyse, nor are all non-crystalline bodies indifFusible; thenon-cystallino peptones, for example, ditluse readily. By this process of dialysis colloidal substances like mucus, albumin, gelatin, gum, &c., can bo separated from crystalloids like salts and sugar. Diffufiion is favoured by agitation, by an elevated temperature, and by a large surface; and the greater the difference in density between the fluids on each side of the membrane the greater will be the rapidity of the diffusion. The process will therefore be quickened by changing the external fluid freqiiently and concentrating that contcxined in the dialyser. The term osmose is applied to this passage of fluids through a membi-ane, this l)eing simultaneously saturated by both liquids, and, according as the passage is inwards or outwards, the process is named endosmose or exosmose respective!}'. The attraction or aflinity of the two liquids for each, other, and the difference in the attraction the diaphragm exercises on each are the chief factors concerned. The size of the moelcules of the substances on each side of the membrane, and of the interstices of the membrane itself, are also of importance. Thus hfemoglobin, although a crystalloid, and albumin, &e., on account of the large size of their molecules, cannot pass through or dialyse. Generally, two currents traverse the membrane in opposite directions, one of which, howevei', exceeds the other in intensity ; but in some cases, as Avhere concentrated colloidal solutions are on one side of the diaphragm and water on the other, the water alone traverses the membrane, A dialyser is readily rrucde by tying a piece of soft moist bladder or parchment papei' over the lower mouth of a glass vessel of conical or bell shape and open above. Care should be taken to tie the membrane on ve7'y tightly, and the membrane should present no fissures : accordingly, after the tying has been completed, pour water into the dialyser thus made, and note if anj' traces of moisture appear on the lower side of the membrane, indicating solutions of continiiity ; this may be noted directly by the eye, or by placing the dialyser on a sheet of blotting-paper. If .«o, brush some white of egg over these spots, and plunge the membrane into hot water to coagulate the albu- min ; or, if nocfssary, stick a piece of fresh parchment over these points ]>y moans of the white of egg, the latter being coagulated by jjassing a hot iron over tbe patch. The dialyser thus constructed is MF/rilons AM) PROCESSES. Fig. 3.— Diai.y.skr. The inner vessel is closeil below witli parchment, which is held iu its place by a closely fitting double elastic rin?. then plact'd upon a tripod in a larger vessel filled with water, or it is suspended in it by means of a thread. Another convenient form consists of a double hoop of wood or guttapercha, the inner hoop being slightly conical and about two inches deep, and the outer about an inch deep, the membrane being fixed be- tween them. This form is used when the licpiid to be diffused amounts to eight or ten ounces ; and it is allowed to float on water in a larger vessel. Small dlalijsers can readily be made from wide test tubes, the parchment being tied over tlie mouth and the closed end cut off. In dialysing, the layer of li(iuid inside the dialyser should not be much deeper than half or three-quarters of an inch, and it is to be gently agitated from time to time ; and the fluid outside ought to be at least four or five times greater in amount. Decantation. — This is one of the methods employed in tiKishincj a precipitate that is heavy and subsides readily. The precipitate is vigorously shaken up with successive quantities of water, which is poured off when the precipitate has settled down ; and it is advisable to let it run along a wet glass rod held in contact with the margin of the containing beaker. At this point a little lard should be smeared on the outer surface, to prevent the fiuid trickling down the outside of the beaker. If the washing is done on a large scale it is better to make use of a siphon. A pipette may be employed to suck off the supernatant liquid when it is present in small amount, and sometimes if the layer is very thin it may be removed by the careful introduction of a fold of filter paper Siphons and pipettes are also useful in separating two layers of different liquids one from the other. Desiccation. — By this process the hygroscopic water that adheres so clo.sely to different substances, particularly those of animal origin, is removed. As a great many organic substances begin to decompose at temperatures above 1 20° to 130° C, it is therefore necessary during the process of desiccation to maintain the temperature between 100° and 120°, and this should be kept constant as far as possible. Many substances bear a temperature of 130° to 140° U. without 8 NUTRITION AND FOODS. decomposition^ but a temperature of 110' is the most generally useful. A square or cylindrical strong copper box that can be readily opened, and which is provided with a j^erforated shelf whereon to place the dish containing- the preparation to be dried, and with an opening in its cover in which a thermometer is fixed, is most frecpently used for desiccation purposes. Care must be taken that neither the ther- mometer nor the drying dish comes in direct contact with the floor or Avail of the drying chamber. A ioashed precijntate still lying in its funnel, if intended to be dried, may fii'st be placed in a small wire tripod standing upon a sheet of wire gauze or netting that is supported at a convenient height over a flame by another larger wire tripod. When nearly dry transfer the filter with its contents to a water bath ; and if a higher tempera- ture is required to complete the desiccation recourse may be had to the process that follows. A good plan for completing the dryiag of jyreclpitates on filtei"S, when they have to be afterwards weighed, is to place the folded filter with its contained precipitate between two watch glasses not her- metfcally closed, to transfer the latter, after having been fixed with metal clips, to the interior of the desiccating chamber for a quarter to half an hour, when they are to be clipped as tightly as pos.sible — the watch glasses should have ground edges to admit of this — and than to leave them under cover to cool slowly over a disli of sulphuric acid, as described in the following paragra]>h. Drying over SulphuriG Acid. — Hygroscopic powders, on account of the rapidity with which they absorb moisture from the air, must, after having been ignited, be allowed to cool under a bell jar, a dish containing sulphuric acid being present. The air in tlie bell jar is thus maintained in a dry state. A dry chamber may also readily be formed by means of a large beaker with ground edges, that are to be smeared with lard, and a smooth plate of glass to be laid thereon. The acid is poured into the bottom of the beaker, and the hygroscopic powder placed between two watch glasses loosely secured by a clip ; the watch glasses are supported on a little tripod made of three small gla.ss tubes fixed together with lead wire. By placing the beaker with its contents, b\it without its cover, under the receiver of an air pump, and then exhausting, a powder may be dried without the aid of heat; but the desiccation lequires several days. To Dry Flasks, Tubing, d-c. — After the Jlask has drained com- jdetely, warm it caiefully and suck the air from its interior from time to time with a long glass tube dipping down into it. METHODS AND PROCESSES. 9 2^^arrow glass tubing may be dried by drawing or pushing a piece of dry filter paper or cotton through it ; but with long and very fine tubes recourse must be had to heating some length of them over a llame and subsequently drawing air through witli tlio n»outh or other- wise. Small tul>es, such as reduction tubes and the like, are readily dried by ])lacing them upon a heated metal plate or in a hot sand bath. Distillation. — The boiling point— that is, the temperature at which dilVeroiit bodies pass oil' rapidly in the form of vapour— varies greatly, Fi«. 4.— Simple Dlstillatiox Appa raits. Tlifi constrnction is very simple, tlie cnmlenser consisting of a wide ,?lass tube tliron^h whioh the narrow gla.33 tube from the flask a passes. A cointant current of cola water is obtained by allowing water to flow from a tap into b : it escapes by r. The coutlenser Is fitted to d. A small glass flask will serve the purpose. some being much more volatile than others. Advantage is taken of this in the process of distillation to separate these bodies. The parts of any distillation apparatus consist essentially of a boiler and of a condenser. A simple form is Liebig's, in which the long neck of a glass retort is inserted into the inner tube of the con- denser, that is made of a tapering glass cylinder fixed by jxjrforated corks in the centre of a wider metal pipe. Between these two tubes cold water is made to circulate, the water entering by a long tube near the lower end, and as it is heated rising and flowing out by a small tube near the upper end. By connecting both these tubes, one with a tap and the other with a sink, by means of indiavubber tubing. 10 yuTinriox Axn foods. the current is rendered constant. The nari-ow end of the condenser dips into the flask or receiver into which the condensed liquid drops. Where the neck of the retort is fitted into the condensing tube the connection should be made air-tight by wrapping a ribbon of sti'etched indiarubber round this part of the neck before inserting it. A thermometer is fixed into the retort by passing it through the cork at its summit, and it shoukl nearly touch the bottom. The heat is gradually applied by a rose or ring burner, or, failing these, by an ordinary Bunsen lamp. Distillation on a small scale can readily be performed by using a ]»lain retort, surrounding its long neck with some folds of Idotting- ])aper, and keeping this wet by water dropping upon it from a bottle placed at a higher level. Failing a retort, the purpose will also be effected by using a Florence flask with a long bent tube fitting into the cork closing it, and dipping loosely through a perfoi'ated cork into another similar flask lying in a basin of cold water. Evaporation. — The usual temperature employed is 100°,' which is ea.'^ily obtained with the water bath ; but when the evaporation is to be done at a lower temperature an air or sand bath can be employed. To prevent loss of jlixid one of these plans can be adopted: (1) Place a small funnel in the mouth of the flask ; (2) fix into the cork closing the flask a glass tube, 2 to 4 feet long ; this tube may be drawn out to a capillary opening at its upper extremity, if necessary ; (3) connect the flask with the condenser of a Liebig's apparatus. Ethcrcctl or alcoholic solutions are to be evaj^orated over a water bath, and not over a naked flame. In evaporating alhumino^is solu- tions avoid charring, and stir frequently with a glass rod during the operation. In heating beakers care should be taken not to apply the naked flame, but let the beaker be placed over the flame on a Avire gauze, or on a flat iron plate supported on a tripod. A satid bath may also be employed. The maintenance of a constant tem/peraXure is best eflfected by a gas regulator (Bunsen's or Page's). Eoughly it may be accomplished by carefully regulating, with the help of a thermometer, the size of the flame of a burner applied to a sand bath, or to a small metal chamber Rurroundoil by a double wall in which water is contained. Filtration. — The filter should always be smaller than the funnel in which it is inserted, and generally it .should be mdistened with water before being used. Pvibbed filters are employed for quick filtra- tions, when the filtrate alone is wanted ; or the filter may be allowed ' When not otherwise indicated, the temijcratures will be given in the centigrade scale. MF/niODS AND PROCESSES. 11 to rest upon three or four glass rods hooked on to the upper edge of the funnel. Double funnels are sometimes required, especially when it is de- sired to keep the filtering fluid hot during its passage through. A double funnel may easily be fitted up by placing a glass funnel inside a larger tin funnel, so that a space may intervene between them, the tube of the glass funnel p:issing through a perforated cork fixed in the lower extremity of the tin funnel. Warm water is allowed to flow into the space between the two from above, and to escape through a small tube below. With voluminous, dense, or mucilaginous deposits, first ])ass through linen or fine muslin, and if necessary through an additional coating of flannel. Filtration may be gieatly ac- celerated by reducing the pres- sure inside the vessel into which the liquid is flowing. This can be effected as follows : Two large glass jars are connected as in the diagram, and the interior of the vessel in which the filter is fixed is brought into connection with the uj>per glass jar. The funnel, which must be perfectly smooth in its interior, passes tightly through the cork, and is accurately fitted with a little perforated cone of thin platinum, in which the apex of the filter rests. The upper jar is filled with water, and when this is allowed to discharge itself into the lower jar a partial vacuum is caused on the lower level of the filter. Incineration. — By this operation the fixed salts of an organic or Fro. -rii;ii:iilN(i AlTAUATCS. and 6 arc tivo large bottle's connected, as indicated in the drawing, by a narrow imliarubbcr tube witli tliick walls. TIk' upper bottle should be placed as high as possible, c is a bottle into which the filtrate is to pass. The interior of tliis ia in connection with a by a thick-walled tube d. Into the stopper of c the funnel e is fixed, and at its apex lies the small plati- nuna funnel/, which supports the apex of tlie filter when the interior of <• is partially exhausted by the discharge of the water i]i (t into b. 1-^ yi'TJRlTION AND FOODS. inorganic compound may be obtained. It can be pei-formed in a small po)celain or platinum crucible supported in an inclined position on a pipe-day or platinum-wire triangle ; but a platinum crucible is not to be used if the substance to be ignited evolves chlorine, bromine, or iodine, or contains phosphorus or phosphates, or if alkaline nitrates, easily oxidised metallic oxides, or organic salts of the hea-\y metals are present: in such cases the porcelain ciucible is to be preferred. It is necessary, before igniting, to dry the precipitate thoroughly, and then to detach it from the filter as completely as possible over a sheet of smooth paper; the collected piecipitate, transferred to the crucible, is then to be cautiously ignited to a dull red heat over a Bunsen lamp, the crucible being covered for the first few minutes of the calcination and then uncovered. Now cut the dry filter into small pieces and ignite them upon the cover of the crucible, add the ash to the crucible, and having again applied the cover, subject the whole to a higher temperature if necessary. When the crucible is to be weighed it should first be allowed to cool over sulphuric acid in a bell jar. Tt should be remembei-ed that a continued red heat causes some of the elements of the ash, such as chlorine, jnai>iic value of a food depends on its richness in easily assimilable proteids, and its calorific value on the quantity of heat it produces when burnt in the organism. But the digestibility of a food must also be taken into consideration as this is more a measure of its nutritive value than its ele- mentary composition. Great' differences exist in the absorp- tion of different foods : thus rye bread, potatoes, and green vegetables produce large quantities of fresh and dry excre- ment ; while white bread, fresh meat, and eggs are absorbed to a greater extent, and are therefore more valuable. Fat of butter also appears easier of digestion than bacon fat ; and car- bohydrates are easily assimilated when contained in white bread, rice, and macaroni, but with more difficulty from pota- toes, rye bread, and turnips ; further, nitrogen is most easily absorbed from meat, eggs, and animal substances generally, but with more difficulty from rye bread and vegetables (Rubner). Where the tinal consumption of the food particles occurs is still to be decided, but it is probable that before the final de- composition products — water, carbonic acid, and urea, am- monia, or some such body — are reached, a series of retroo-rade and intermediate processes have occurred in the livino- cells of the tissues themselves, and in the fluids immediately bathino- them; and it is possible that some of these changes normally take place in such great central vascular organs as the liver and spleen. In the normal condition an equilibrium is maintained hetiveen the ingesta and the egesta. The following table, giving the results of a series of three days' experiments made on a dog, shows this distinctly (Pettenkofer and Vorr) :— c 2 L^O HUTRTTION AND FOODS. A. Food: flesh, 1,500 grams; oxygen absorbed, 477-2 grams; total, 1977*2 grams. B. Excretions : total, 201 1-8 grams. c. H. K. 0. Mineral salts Dry solids 704-7 Urea 21-6 7-2 50-4 28-8 and gases Orsanic salts of urine 9-6 2-5 15-9 16-3 Dry fteces . . 4-9 07 07 1-5 3-4 Carbonic anhydride by lungs and skin 146-7 i 391-5 Marsh g-as by lungs and skin 1-2 0-4 Hydrogen 1-4 Water ex- 1307-1 Water of urine 102-5 820-3 creted Water of freces Water by lungs and 3-2 26-3 skin 39-4 315-4 2011-8 184-0 157-3 51-1 1599-7 19-7 All the nitrogen leaving the body is calculated as urea, which gives a slight excess. It is to be remarked also that while the dog absorbed only 1138-5 grams of water he excreted 1307-1 gi-ams, from which it follows that the 168-6 grams in excess have been formed at the expense of the tissues or organs. Of the 477-2 grams of free oxygen absorbed 391-5 are excreted in combination with carbon as free carbonic anhydi-ide, and 149-9 grams in combination with hydrogen as water, or in the proportion of 3 to 1, a proportion which in man is about as 7 to 1. Of every 100 degrees of heat pi^oduced, therefoi-e, in the living organism 8 1 "5 ai'e due to the combustion of carbon, and 18-5 to the combustion of the hydrogen of the food ingested. Taking all these facts into consideration, the heM food for repairing the losses of the organism would be one consisting 01 Grains Dry proteids ..... 1,913 Dry starches . . . . .6,172 Fat.< 1,142 Total \),TI1 FOODS. 21 requiring about 1 1,000 ijrains of oxygen for their combustion, giving for tliese bodies respectively nearly the relative proportions of 1 : S-20 : 0"6, or 1 of pro- teids to 3-8 of the combined starches and fats ; proportions closely correspond- ing to those given b}' JIoleschott, who established the relation of the proteids to the two other combined foods as 1 : 3'75. LlEBiG gave it as 1 : 3 ; and that of the fats to the starches as 1 : 5'4. These proportions would be obtained in a daily food made up of white bread 1-8 lb., lean meat 053 lb., and fat 0'13 lb. Proportion of the Chief Tissues forming the Human Body (Bischoff). Weight in adult Man (set. 33) New-bom male as comjiared with child tliat of tlie infant taken as 1 Per cent. Per cent. Muscles .... 41-8 22-9 28 Fat . 18-2 witli skin 200 — .Skeleton . 15-9 17-7 2(J Abdominal viscera 7-2 ll-o 15 Skin . 6-9 11-3 12 lirain 1-9 1.5-8 3 7 Thoracic viscera 1-7 30 17 The muscles thus form nearly half of the body, and they contain quarter its total blood ; and of the abdominal viscera the most important is the liver, which also contains about a fourth of the whole blood. The chemical composition of the different tissues will be taken up subsequently. Keference will be made here only to the water and the salts entering into their constitution. Water forms about 70 per cent, of the adult, and 88 per cent, of the embryo, and is the medium in which the chemical changes of the organism occur. In the accompanying table the average proportion of water in several of the tissues is given : — Per ;ent. Per cent Lymph . 93- -96 Brain . 75 Chyle . 90- -95 Cartilage . . 67-73 Blood . 78 Bones . 13 Kidneys . . 82 Teeth . 10 Nerves . 78 Enamel . . 0-2 Muscles . . 76 Salts. — The mineral salts form 3 to 6 per cent, of the adult's body, and about 1 per cent, of that of the foetus. They are obtained as ash when the tissues are calcined, but part of them result from the oxidation of the sulphm- and phosphorus of some y J "n: IT I ON ani) foods. of the organic constituents. The heat also decomposes and Yohitilises a few of the components, such as certam chlorides and carbonates. It must, therefore, be remembered that the analysis of the ash does not represent the true composition of the salts as they existed in the living tissue. Alkaline chlorides and phosphates, earthy phosphates, with some carbonates and sulphates form the chief of these salts, of which sodlc chloride is the most important, its presence exciting assimilative changes and assisting in the secretion of many of the juices, particularly the gastric ; and so necessary is it to the organism that when it is supplied in insufficient quantity it is retained by the tissues and not excreted. When deprived of it animals lose weight, spirits, and activity. The 'potash salts are also indis- pensable, acting as exciters of the nervous system and increasing the cardiac pulsations. A great daily loss occurs in the salts, which of course must be restored in the diet. By the urine of a healthy man of average weight, for example, there is a daily discharge of about 180 to 250 grains of chloride of sodium and about 120 to 130 grains of other salts, and by the faeces about 130 to 140 grains of different salts. These salts are principally phosphates of potash, and phosphates and carbonates of lime, &c. Accord- ingly the food should contain at least 250 grains of sodic chloride, and about half that amount of other salts, especially those of potash, to make good this daily loss. The distribution of these salts in some of the organs and fluids of the body can be seen in the adjoining table (after G-autier) : — Asli Brain Jlusole Milk Blooil Yolk of egg Potassium 32-4 34-4 21-4 11-2 8-9 Sodium . 10-7 2-4 — 6-3 5-12 Magnesium \-2?, 1-15 0-87 1-26 2-07 Lime . . 0-72 1-9!) 18-8 i-8r> 12-1 Sodic cldoridc . 4-7 ]0G 10-7 3G-3 — I'otassic „ — — 2(;-3 20-5 — I'liosplioric a(;id 48-1 48-1 ]i)l 8-8 78-9 Sulphuric „ 0'75 — 2G 711 — Silica 0-42 0-81 — — 0-5 Saliiicr inciters are evideiilly associated with ihe different forniaiivc jtrocesses occuiring in the body, and we find no in- discriminate dilfiision, but a regular and special distribution of tiieni in the dititerent organs and tissues of the organism. It is easy to see, then, that mineral salts require to be supplied for the nutrition and growth of the different parts of the system, and also for the formation of the secretions. So important indeed are the salts of the food that animals dieted with food from which all inorganic salts have been removed rapidly die ofir(FoKSTP:K), due partly, in Bunge's opinion, to the formation of free sulphuric acid from the albuminoid sulphur, and the consequent abstraction of basic constituents from the intes- tines. The combinations therefore required are salts of lime, magnesia, potash, soda, and iron, with chlorine, phos})horic and sulphuric acids, the lime and phosphoric acid appearing to be specially important. All these combinations are present in the meat, bread, and fresh vegetables ingested. As examples we shall cite here the composition of the ash of wheat and milk in the 100 parts. Ash of wlieat Ash of cow's milk rhosphoric acid (P.O,) . . . . 43 5 28-40 Potash . . ' 32-4 23 46 Magnesia 13-!) 2-2 Lime 3o 1734 «ilica 305 — Soda 2-3 6-96 Ferric oxide TO — Sulphuric acid ...... 0'35 — Potassic chloride . , . . . — 14-18 Sodic „ — 4-74 Potash salts are abundant in the potato, constituting more than 50 per cent, of the ash, which is, however, not very abundant, varying from 0'8 to 1 -3 per cent, of the fresh potato. The alkaline citrates, tartrates, and malates of the vege- tables eaten are burnt in the organism to the state of car- bonates. Mixed Diet. — Different experimenters have proved that a normal food must not consist of one aliment exclusively (Chossat, Kanke), whether nitrogenous, starchy, or fatty ; further, as no one food contains the different essential prin- ciples in the necessary proportions, a mixed diet must be employed, and the nature of this diet must vary with the 24 ^UTIilTIOX AXI) FOODS. inanuer of living, with the climate, and with the seasons. The diet must also be in sufifieient quantity, and without any excess in the animal or vegetable components. The necessary nitrogen and carbon will accordingly be best, and so far as the organism is concerned most economically, obtained from a mixed dietary. Upon it, indeed, man appears to attain to his finest development of physique and highest vigom- of intellect, this mixed diet at the same time being most conformable to the character of his teeth and digestive apparatus. A diet, however, from which meat is largely ex- cluded may often, it may be observed, be used with advantage, but under most circumstances the most suitable admixture contains one-fom-th or rather more of animal food. Thus 2 lbs. of bread and | lb. of beef will supply the necessary amounts of carbon and nitrogen, which would require over 6 lbs. of m.eat and more than 4 lbs. of bread if either is taken singly, these amounts, moreover, gi^dng a large sm'plus of carbon in the case of the bread and of nitrogen in the case of the meat. Classification of Foods. — Dumas and Liebig divided foods into assimilable or plastic and combustible or resjpiratory ; but, as all foods are in reality plastic, the division is an inaccu- rate one. More correctly foods may be classified, according to their composition, into — Organic /"Nitrogenous . Albumins, &c. J ( Fats Inorganic Non-nitrogenous ^ [ Water I. Salts Carbohydrates, together with the alcohols and vegetable acids Kanke maintained himself in good health, neitlier losing nor gaining weight, on a diet of tliis kind : — Proteids . Fat Amyloiils Salts Water 2,600 40,120 Grams Grains 100 1,540 100 1,540 240 3,700 25 380 FOODS. Dht for a U'orki'if/ Man uf Arrriuje IMi/ht and WVnjht (MOLESCHOTT). Albuminous matter Fatty Carbohydrates Salts Total . (Intiiis 130 84 404 30 648 Ounces 4r>8 2-96 14-25 1-OG 22-85 The above 23 ounces of dry solids would correspond to ratber more than double that amount of ordinary solid food, with which requires to be associated about 60 to 80 ounces of water. On a previous page it is stated that 2 lbs. of bread and \ lb. of lean meat will supply the necessary carbon and nitrogen required. In the annexed table, which gives a suita- ble diet for active labourers, we shall compare the two diet- aries. Diet of Active Labourers (Playfaik) Bread, ,^?" v! n Bread and 2 Ite. ("n|ooked), ^^^ Nitrogenous matter Fat ... . Carbohydrates Minerals Oz. 50-5-6 2-4-2-9 17-9-22-2 0-7-0-9 Oz. 2-59 0-51 16-32 0-74 Oz. 232 4-9 0-43 0-9 — 10-3 0-61 1-3 In these dietaries the nitrogenous matter present forms one-fifth to a little more than a sixth of the total solids. CHAPTER V. THE NITROGENOUS FOODS. NITROGENOUS FOODS.— The chief of these are the alhii- mins, albumin by itself forming by far the most important single element, since it contains nutritive material in a condensed and easily assimilated form, it s composition being more or less identical with the albumins of blood and the animal tissues. Examples of rich albuminous foods are white of egg, casein, legumin, gluten, and syntonin. Next come the collagens, or bodies l>0 yrT2U7'iox Ay I) toons. that yield gelatin, or an analogous substance, on boiling, as ossein and cliondrin ; then there are such bodies as kreatin, kreatinin, xanthin, and the like, which may be regarded as disintegration products of the proteids, and which are present in meats. In the table a series of different articles of food rich in these albuminous principles are^ compared. A. Animal Albumins. lilch Alhiiunnoux lAiads (« fte?- Ranke, P AYEN, LETHEBY, S ^•) ^ o bf c 5 ^ o ^ ^1 3 St? 3 ^ "3 o « o s bo 1 S 1-1 3. ° =H CI B fa > fa ^ o ^ Nitrogenous matter 19-3 14-8 •27-6 18-3 12-4 lG-6 9-8 88 18-1 16-1 14-01 14-0 Pat . 3-G 29-8 15-45 4-9 3T1 15-8 48-9 73-3 2-9 5-5 1-51 10-5 Salines, &c. 5-1 4-4 2-95 4-8 3-5 4-7 2-3 2-9 1-0 1-4 4-09 1-5 Water 72-00 51-0 54-00 72-0 53-0 63-0 39-0 15-0 78-0 77-0 80-39 74-0 Composition of Beef, Veal, and Pork (Moleschoti ) Soluble ilbumin and hjematm Mj-osin, &c. xelatins Pats Extrac- tives Ereatin Ash Water Beef Teal . . Pork i,'J5 2-27 1-63 15-21 14-36 15-50 3-21 5-01 4-08 2-87 2-56 5-73 1-39 1-27 1-29 0-07 1-C U'77 1-11 73-39 73-75 70-06 If the yolh is compared with the luliite of an egg it will be found that of the nitrogenous constituents there are 20'4 per cent, in the white and 16 in the yolk, 30 per cent, of fat in the yolk, 1*6 per cent, salines in the white and 1*3 per cent, in the yolk, and 78 per cent, of water in the white and 52 per cent, in the yolk. Good neiu milk contains about 546 grains carbon and 43 grains nitrogen in the imperial pint. Water Nitrogenous constituents Sugar Pat Salts Milk (New . . . \Skim . 8G 88 5-5 4-0 3-8 3-8 3-6 1-8 0-66 0-8 The essential constituent of cheese is the casein or curd of milk. Cheeses vary very much in their composition, but an average good skim-milk cheese contains: water 44 per cent., nitrogenous constituents 44*8, fatC'S, and salts 4-9 ; and a good THE yiTIiOGEXOUS FOODS. 27 new-milk cheese : water 3G per cent., nitrogenous constituents 28*4, fet 31 "1, and salts 4*5. Cheeses like the former require a longer time for digestion than the latter, which take about 3 to 3^ hours if of medium age. Cheese contains calcic phos- phate and oxide of iron, and there is present in dried cheese deprived of fat and prepared from fresh milk 3'5 to 4 per cent, phosphoric anhydride and 4*3 to 4'7 per cent. lime. Analyses of ChceM'S. Cheese Nitrogenous const! i,ueuts Fats 25-48 28-00 32-31 3 11 240 21-0 Salts 4-78 4-79 4-45 4-5 30 4-7 Water Cheshire Gruyere Roquefort Cheddar Gruyere Camembert . 36-14 35-10 32-95 28-4 31-5 18 9 30-39 1 32-05 .(Malagutti) 26-53 J ^^^.-^ICPAYEX, 5i-9 J P^^^^^) B. The Vegetable Albumins nre not so rich in carbon as the animal albumins, but are richer in nitrogen ; this pro- bably accounts for their less nutritive value and the greater difficulty in their assimilation ; they are, however, like eggs and fish, very rich in phosphorus. It may be stated generally that vegetables are more difficult and slower of digestion than most animal foods, but that when combined with the latter in suitable amount the digestion is rendered easier and the assimilation more perfect. Garlic, onions, radish, turnips, &c., excite the digestion, and at the same time stimulate the urinary and generative organs. A 71 all/ sex of Yegctahle Grains, Seeds, tSr. (Payen, Letheby, Eoussingault, <5-(?.) starch, sugar, and Proteids Fats Cellulose, &c. Minerals Water dextrin Wheat . 68-9 14-6 1-2 1-7 1-6 14-0 Rye 67-5 9-0 2-0 3-0 1-9 16-6 Oats 61-5 11-9 5-5 4-1 3-0 14-0 Rice 78-30 6-43 0-43 0-5 0-68 14-4 Barley . 63-6 13-4 2-8 2-6 4-5 13-0 Peas 58-5 25-4 2-0 1-9 2-5 9-7 P>eans 48-3 .30-8 1-9 3-0 3-5 12-5 Indian corn 65-1 111 8-1 — 1-7 140 Potatoes 21-09 1-6 0-11 1-64 1-56 74-0 Carrots . 14-5 1-3 0-20 — 1-0 83-0 28 NUTRITION AND FOODS. The amount of proteids in potatoes is given by E. Sciiultze as varying between 0*65 and Tl 9 per cent., but as 2'34 per cent. l)y HoLDEFLEiss. The ash of potatoes is very rich in potash salts. Analysis of Bread and Biscuit. Carbohydrates . Nitrogenous constituents Fats Minerals ... Water ur bread Biscuit 51-0 73-4 8-1 1.5-6 1-S 1-3 2-3 1-7 ]7-0 8-0 A na li/ses of /' r II its (1 "resenius). Apoles Pears Green- Cherries Grapes Gooseberries Straw- (white) (sweet red) gages (sweet red) (wliite) (larere red) berries Sugar . 7-58 7-94 3-4 13-11 13-78 8-06 7-57 Free acid (ex- pressed as oxalic) 1-04 trace 0-87 0-35 1-02 1-35 113 Albuminous sub- stances 0-22 0-24 0-40 0-90 0-83 0-44 0-36 Pectous substances and pectose 3-88 5-10 12-52 3-73 1-43 1-26 1-12 Ash . 0-44 0-28 0-39 0-60 0-36 0-31 0-48 Insoluble matter . 1-8 3-51 3-89 5-9 2-59 2-99 1-96 Water . 85-04 83-01 79-72 75-37 79-99 85-56 87-47 In mixed vegetables it may be stated generally that 1 lb. con- tains about 420 grains carbon and 14 grains nitrogen. When potatoes are compared with bread as to nutritive power, it will be seen that 1 lb. of bread is equal to 2^ lbs. of potato in carbon and to 3^ lbs. in nitrogen. Some recent analyses of cabbages show that they are richer in nitrogenous substances than has hitherto been sup- posed, the total albuminoids (N x 6*25) in the dry matter of the leaves averaging 12 to 28 per cent., and in the stems 11 to 15 per cent. (Leizour and Nivet). Edible mushrooms., although difficult of digestion, are rich in proteids, containing as much as 52 per cent, of nitrogenous matter in the di-y state. An analysis of Pa yen's i^ives the following : — Nitrogenous matter and traces of sulphur ..... 4-68 Fatty matter 039 Cellulose, dextrin, and sugar . . . . . . .3-16 Salts (phosphates and chlorides of tlie alkalies, liuio, and magnesia) 0-4() Water 9101 Tea cannot bo regarded as a nutriment in the sense of supplying material to maintain structure and genei-ate heat ; it rather tends THE NITROGENOUS FOODS. 29 to excite vital activity, particnlailj acting as a i'es])iiatoiy stimulant. But while tea alone affords little nutritive material the addition of sugar and milk converts it into a useful food. Analysis of Tea (PJCLlCiOT). Per cent. Per cent Thcine . . 20-30 Fat . . 40 Casein . 15-0 VegeLaMe libic . 200 G uni . 18-0 Minerals . . 50 Tannin . 2{y->r-, Water . fvO Starch . 0-75 Coffee also excites the nervous system, but not to the same degree as tea, whilst it somewhat depresses the respiratory function. It exerts a marked sustaining influence under fatigueand privation, and it appears to diminish the waste of the tissues (Leiimann), or to render the elements of the body more stable (Gasparin), thus economising other nourishment ; but both theories are doubtful (Roux). Among vegetables %ve may distinguish— 1. Those rich in albumin and nitrogen — cabbage, aspara- gus, cress, mushrooms, and truffles. These are all very nutri- tious, the two latter yielding from 3*1 to 7 per cent, nitrogen (8cfilossberger). The young cabbage contains from 1*5 to 2 per cent, of nitrogenous ingredients (Anderson). 2. Those rich in mucilage and salts — white beet, lettuce, and endive. They contain much water, mucilage, inulin, and malates, oxalates, &c., especially of potash and lime. Potash salts predominate in sour kraut, Brussels sprouts, and asparagus, and soda in spinach, &c. 3. Those rich in acids — sorrel, tomato, rhubarb, asparagus. They are useful as excitants of digestion. 4. Those containing little or no starch — lettuce, endive, spinach, asparagus, artichoke, leeks, white onions, and pars- nips. 5. Those rich in sugar — beet roots, Jerusalem artichokes, carrots. Eipe fruits also contain much sugar. Among fruits we may also distinguish (GtAUTier) — 1. Those containing much sugar — pears, apples, peaches, apricots, prunes, melons, oranges, strawberries, figs, grapes, &c. 30 NUTRITION AND FOODS. When ripe they are easy of digestion, and generally contain such vegetable acids as malic, citric, tartaric, &c. 2. Acid fruits — lemon, gooseberry, tamarind, &c. — contain less sugar but a greater amount of acid than the preceding. 3. Starchy fruits — chestnuts, breadfruit. 4. Oily fruits — nuts of different kinds, sweet almonds, &c. In conclusion, with regard to albuminous foods it may be stated, in general terms, that luherever vital operations are going on there nitrogenous matter is to he found, the operations of life occurring through its instrumentality. The nitrogenous tissues, which are the machines for living actions, have first to be constructed and then maintained. Accordingly nitrogenous food is required for the construction as well as the maintenance of the tissues. Hard work is best performed with an abundant supply of proteids, as this leads to a better nourished condition of the animal machine and its component parts, such as muscle and the like ; and to keep up this good condition for work a liberal supply of nitrogenous food is absolutely essential. In addition to supplying the nitrogenous waste, and forming one of the great sources of fat in the economy, the proteids excite the metabolic activity of the body, and hence they are not stored up so readily as the fats and carbohydrates. CHAPTER VI. FATS, CARBOHYDRATES, AND MINERALS. FATS AND CARBOHYDEATES.— Starch, sugar, and dextrin are easily assimilated, but the gums and celluloses are not so. In the previous chapter reference has been made to the amount of these carbohydrates and fats present in different foods. These bodies may, to a certain extent, replace the nitrogenous foods. The proteids, we have seen, can undergo metamorphoses fitting them to evolve energy, but the combustible material which evolves energy most largely and efficiently is supplied in the fats and carbohydrates; indeed, as force- producers they possess a very high dietetic value; andasgn-iit storehouses of potential FATS, CARBOHYDRATES, AND MINERALS. ,31 energy they may be regarded as the ultimate, though not necessarily the direct sources of heat as well as of muscular energy. The potential energy of the fats, however, is much greater than that of the carbohydrates, developing more than twice as much heat. With a fixed quantity of the fats or carbohydrates an in- crease in the accompanying proteid leads to an increase in the carbon consumption, owing to the proteids favouring an increase in the metabolism of both kinds of food. As to the role played by alcohol in the economy there is still some difference of opinion, but the weight of evidence is in favour of the theory that it acts more or less as an aliment. When ingested in excess much of it traverses the system un- burnt, and is then found in the urine, sweat, and expired air (Lallemand, Perrin, &c.) ; but when taken in a moderate dose the amount eliminated liy the urine forms but a small proportion of that absorbed (Dupre) ; some even maintain that the quantity thus excreted does not amount to more than 0'7 per cent. (Thresh), The chief portion of the alcohol in the latter case, therefore, undergoes consumption in the body (Anstie, Thudichum, Schulinus, Baudot, &c.) We shall see elsewhere that a little alcohol is even generated in the tissues of the organism itself (BECHAMr). Alcohol does not appear to increase the production of heat as a chemical agent (E. Smith), rather in large amount lower- ing the temperature by checking some of the oxidations occur- ring in the body, particularly when abnormal, as in fevers. It also, when given in a state of health, tends to diminish muscular power, but indirectly the effect may be to increase it by im- proving the tone of the system through the aj^petite and dio-es- tion of food. While the carbonic acid exhaled is slightly diminished when wines and beer are taken in moderate quantity, the secretion of the gastric and pancreatic juices is favoured, and there is a gentle excitation of the nerve centres, and at the same time an undoubted addition made in the form of salts fats glycerin, and albuminoids — beer not only being stimulating and tonic, but also nutritious. Indeed, of the alcoholic drinks beers occupy the first place as foods ; then come cider and 32 NUTBITIOK AND FOODS. perry, mid then wines ; and as they sustain and increase vital action they must be regarded as true foods (E. Smith). Ac- cording to VoiT also alcohol must be regarded as a food, as tinder its influence fewer substances are decomposed in the body. MINERALS. — -The several salines, including the extractives of animal and vegetable food, are, in a sense, quite as essential elements of a dietary as its proteids, fats, or carbohydrates. They appear to regulate in some way the energy of the food stuffs (Foster), a diet from which phosphorus or phosphates, chlorides, and potash or soda salts are absent, being useless for nutritive purposes. The important salts in the organism have already been referred to (p. 22), and it has been pointed out that of the inorganic foods the moat important is ivater, which forms about 75 to 85 per cent, of the body weight. It is required to maintain the due bulk of the blood and other animal tissues of which it is so large a constituent, and in addition it is useful in mastication and digestion, facilitating these processes, and in keeping up the constant outpourings and reabsorptions of great volumes of liquid in the alimentary canal, and in the tissues generally, by which the body fluids, and particularly the blood, are maintained in a normal condition. It also keeps different substances in solution or suspension in the body, and serves as a vehicle to carry away waste products, and at the same time regulates the temperature of the body by its evaporation at the surface. There is about 15 to 25 ounces of water contained in the solid food taken in the 24 hours ; but besides this 60 to 70 ounces more are required. The remaining salts of importance are sodium chloride, carbonate of lime, and the phosphates of potash, soda, and lime, and in smaller amount salts of magnesia, iron, and silica. If an animal is deprived of these salts they will diminish in the urine. They are required to maintain the constitution of the tissues, and they are essential in keeping up the diffusion streams in the organism. Some of tlie salts fulfil a special function: thus the hydrochloric acid of the gastric juice is formed at the expense of the chlorides, while the alkaline car- lionatcs and the alkaline SJxlts of the vegetable acids serve to FATS, CyiltBOIIYDRATl'S, AXl) MIXKRALS. 33 nouti';ilisc llie sulj)luiiic and pliosphorie acids foniied in I lie system by the oxidaiion of the sul})hur and phosphorus of the proteids, soda piol)ably plnying a siniihir role. Under normal conditions it is probable that the food contains an excess of salts; these are generally excreted in the urine, although it is possible that occasionally some of the excess may l)e stored up in the organism, so that at times more salts may be excreted by the urine than is taken in the food without any consequent evil results. It should be remembered that the change of food in children from one purely of milk to a mixed diet may result in a considerable deficiency of lime salts — a purely flesh diet,, for example, being very poor in lime. CHAPTER YII. STARVATION. Let us now briefly consider some of the changes that occur in the body when it is deprived of a sufficiency of food. By star- vation the greatest loss occurs in the adipose tissue and glandu- lar organs, as seen in the following table of Voit's, recording the results of starving a cat for 13 days : — Adipose tissue . . lost OT^O per cent, of its original weight. Hpleen . . . „ 63-1 ,, Liver . . . „ 5G-6 „ „ „ Skeletal muscles . „ 30"2 „ ,, „ Blood . . . „ 17-6 „ „ „ Brain and spinal cord „ O'O „ „ „ Accordingly we find that the destruction of albuminoids, when the organism is deprived of food, is determined not only by the size of the organ, but by the amount of fat present — the more the fat, so much the less destruction of albumin. This VoiT found to be the case with cats and dogs ; and it holds good also with herbivorous animals, such as rabbits, the decrease of fat being correlated to an increased consumption of albumin — this being longer delayed in an animal rich in fat, but manifesting itself in a few days in lean animals, albumin alone being ulti- mately consumed (Kui5>'ER). The influence of the fat KiCKEix D 34 NUTRITION AND FOODS. assumes to be exerted in restraining the solution and circulation of albiiminoids, and the consequently smaller chance for their disintegration, this influence being chiefly exerted by the fat present in the juices and in the organs where the albumin dis- integration occurs, and not by the fat stored up under the skin and serous membranes, &c. According to H. Ranke, in children dying from wasting diarrhcea, atrophy of the various organs occurs, just as in animals dying from starvation. In Ohlmijller's experiments the bones and brain lost much less weight than the other organs, but the skin decreased considerably, owing to the com- plete disappearance of the adipose tissue. In the normal infant there are 40 per cent, of solids, but in the atrophic only 24 per cent., the relative increase of water being due to the less amount of fat constituents, which are only 3 per cent, in com- parison with 21 per cent, in the normal infant. The active organs upon which the maintenance of life depends are pro- tected from decrease possibly at the expense of the organic albuminoids, which, becoming fluid, enter the circulation and are consumed ; only when this supply fails do these organs besfin to suffer loss of substance. CHAPTER VIII. CHEMISTRY OF THE ALCOHOLS AND FATTY ACIDS, <<)■€■ Reference will be made to but a few of these bodies, and only so far as it concerns our present subject. For additional details the student is referred to one of the larger text books on organic chemistry. A. The term alcohol is applied to compounds of hydroxyl (OH) with univalent or multivalent hydrocarbon radicles, or more simply alcohol may be looked on as water, tt [O, in which half the hydrogen is replaced by an organic radicle ; and accord- ingly alcohols may be regarded as the Itydroxyl substitation derivatives of the hydrocarbons, being therefore the organic analogues of the metallic hydrates. CHEMISTltY OF THE ALCOHOLS A^D FATTY ACIDS. 35 From propane, CgFfg, are thus derived the three alcohols : proj)}'! alcohol, C3H^(()H); propenic alcoliol, or propyl glycol, C3Hg(01i)^; and propenyl alcohol, or glycerin. Of the chief alcohols there are three classes : monatoraic, as methyl alcohol, CH^OH, and ethyl alcohol, C^H.OH ; diatomic, as the (jlyajh, ethyl glycol, C^H^COIT),, propyl glycol, C3He(OH)2, and butyl glycol, C4Hg(OH)2; and triafoTtiic, as glycerin, 031X5(011)3. C H ) Cholesterin is a true alcohol, '■^^tt'*^ 0, and is probably the only one found as such in the body. ETHYL ALCOHOL ( aHgO).— This is the well-known alcohol of commerce, and is chiefly obtained by the fermentation of cane and grape sugar, in wliich process carbonic anhydride is evolved and alcohol formed, a number of other bodies making their appearance in addition, as glycerin, succinic acid, cellu- lose, fats, and occasionally lactic acid. The aiwmge&i rectified spirit of commerce contains 13 to 14 per cent, water, and has a specific gravity about 0-835. Ahso- lute alcohol, as its name implies, is free from water; it is colourless, and has a specific gravity of 0-7938, boiling at 78'4°. Proof spirit has a specific gravity of 0*919, and contains 49j per cent, alcohol. Methylated spirit is a mixture of 90 per cent, spirits of wine of a density of 0*83, and of 10 per cent, partially purified wood spirit (methyl alcohol). When alcohol is heated in a test tube, either alone or with caustic potash, it volatilises without being blackened, its vapour having a characteristic odour and being combustible. It is not blackened when heated with sulphuric acid. "When a little strong sulphuric acid is added to it, and then some dilute solution of potas^ic bichromate {^ per cent.) poured into it, a green colour is produced at the point of contact. To Separate Alcohol from Organic Tissues or Fluids. — Boil for some time with water, or boil their watery extracts, and then distil. In the case of urine add tannic acid before distilling. The distillate must be rendered alkaline with caustic potash and again distilled. This last distillate is acidified with sul- phuric acid and distilled for a third time, when all the alcohol will be present in the receiver. It may be rendered anhydrous by distilling it once again after saturation with rpiick lime or potassium carbonate. D 2 •30 NUTRITIOX AXJ) FOODS. With vomited matter, or where much alcohol is present, it is advisable to make a series of distillations after successive additions of sodium chloride to the fluid in the receiver. To determine qnant'itativdij the alcohol is first transformed into acetic acid, and this determined volumetrically. To effect this conver- sion sulphuric acid and some potassic bichromate solution (one-third per cent.) are added to the fluid, and the whole heated for two hours in a water or sand bath at 80° to 90^ The resulting acetic acid is dis- tilled out and the distillate titrated with standard soda solution. GLYCERIN (Propenyl Alcohol), CgH/Jg or ^^H.Jq^ _This is a triatomic alcohol which forms a nearly colourless, viscid, and very sweet syrupy liquid that is very hygi-oscopic and very soluble in water and alcohol, but insoluble in ether. At 15° it has a specific gravity of 1*26, begins to evaporate at 100°, and boils at 290" ; it forms a gummy mass at —40°, and crystals have been obtained of it belonging to the rhombic system. Glycerin dissolves up, especially with the aid of heat, the oxides of copper and lead and of the alkali metals, &c. ; the fatty acids, iodine, and many organic bodies, such as cholesterin and uric acid, are also dissolved by it, and it acts as a particu- larly good solvent for the ferments. Glycerin oxidises easily in the air, and rapidly reduces silver nitrate. Preparation. — It is obtained in the saponification of fats by caustic alkalies, or by the decomposition of these bodies by superheated steam. When stearin is boiled with caustic potash a stearate is formed, and glycerin is set free : (C.«H3,0)3) K| _ 3C, JT3,0) ^3 C3H0 (tristc'vrin) (polas.sic stearate) The formation of gh'cerin may be shown on a small scale by mixing a little fat with some finely powdered plumbic oxide and water, and then heating; a lead plaster is formed and glycerin remains in solution in the water. Filter and pass a current of snlphurotted hydrogen through the liquid, evaporate to a small bulk, mid filter again. Combinations, &C. — t!H).^] by their oxidation give rise to two series of acids, the gli/collic (C^Hj,^^) and the oxalic {C,^'R^n_,Jj^'). Thus ethene alcohol or ethyl glycol treated with nitric acid gives up 2 or 4 of its hydrogen atoms in exchange for oxygen, according as the oxidation occurs at a low' or a high tempera- ture, glycollic or oxalic acid being produced, as (ethyl glycol) (glycollic acid) C,H/)3 +0, = C^H.O, + H,,0. (oxalic acid) 3S NUTRITION AND FOODS. Of the glycollic or lactic series the important members, phy- siologically speaking, are carbonic (HoCOg), glycollic (HC2H3O3), and lactic (HCgHgOg) acids. With the exception of the car- bonic they are all monobasic. The important members of the oxalic series to which refer- ence will be made are oxalic (HgCgO^) and succinic (H^C^H^O^) acids. These are all dibasic. I. The fatty or acetic acid series. Formic acid .... CH^O^ or CHO.OH Acetic „ C2H4O2 „ C2H3O.OH Propionic „ .... C.JIfi^ ». C3H5O.OH r.utjric ,, .... C^HgO^ „ CjHjO.OH Valerianic „ .... CsHinO^ „ CjHgO.OH C'aproic , C6H,,,0., „ CeHjiO.OH Palmitic „ .... C,„H3,02 „ C.^Hj.O.OH Stearic „ .... C^Hs.O^ „ C.^HsAOH FORMIC ACID, CHO.OH, has been found in several organs and fluids of the body, such as the spleen, pancreas, thymus, and brain, and in the juice of muscle. In leukaemia it is more generally spread, and may present itself in the blood, urine, sweat, and marrow. It is obtained by the oxidation of organic substances in general, such as sugar and starch. Formic acid acts as a powerful reducing agent, as can be shown by heating it with silver or mercuric salts; and it may be regarded as one of the excretory pi^oducts of tissue change, though it is in great part further burnt to carbonic anhydride and water. ACETIC ACID, C.HaO.OH or CH3C0.01I,is a colourless liquid, the strongest foi-m solidifying to an ice-like mass below 15"^, and hence the name glacial applied to it. It is present in the juice of muscle and of many glands, as the spleen, &c,; also in bile and sweat, and in the stomach and intestine as the result of fermentations, especially after the ingestion of sugar and starch, particularly in catarrhal conditions of the luucous mem- brane. The glacial acetic acid is prepared by distilling sodic acetate with strong sulphuric acid. Acetic acid forms normal or neutral acetates, as KC2H3O2 ; and acid salts, as KC.^HgO.CoH^O. With lead the following salts are formed : oiormal acetate, or sugar of lead, Pb(C2HjO.^).2, which is solu- ble in alcohol and slightly soluble in water; and the basic salts or stib- acctates : scsquibasic acetate (Goulard's extract), 2Pb(C.2H302)2PbO ; triplumbic acetate, Pb(C._,H302)22PbO, obtained by mixing a cold saturated solution of the normal salt with a fifth of its volume CIIEMISritY OF THE ALCOHOLS AND FATTY ACIDS. 39 of ammonia ; and srxjduiiihic acetate, Pb(C2H;j02)2-'^P^^j formed by adding a great excess of ammonia to a solution of the normal salt. Test. — It gives a red colour, but no precipitate, with feri-ic chloride (FeaClc), but this colour is discharged by hydrochloric acid. The same red coloration is also given with formic, pyrogallic, sulpho- cyanic, and meconic acids. But the formic and pyroyaUic acids pre- cipitate silver nitrate solutions with reduction of metallic silver, and the pyrogallic acid gives also a blackish blue coloration with ferrous sulphate. The i-ed coloration given by sulphocjjanic acid is discharged by mercuric chloride, but not by hydrochloric acid, while that given by inecoidc acid is removed by neither of these bodies. To separate acetic acid the general plan may be adopted of making two distillations of the liquid containing it, the first being made after the addition of a few drops of sulphuric acid, and the resulting dis- tillate then saturated with carbonate of soda, evaporated to dryness, and again submitted to distillation after being dissolved up in dilute sulphuric acid. Formic acid may be present in the distillate, but it can readily be separated by boiling the distillate with mercuric oxide, which decomposes the formic acid. PROPIONIC ACID occurs sometimes in the sweat, and occa- sionally in fermenting diabetic urine, and in the intestinal tract ; it has also been described as present in the blood in leukiemia. and in the vomited matters in cholera. BUTYRIC ACID. — Two modifications are known — normal or fermentation- butyric or ethyl-acetic acid, and isobutyric or dimeth- acetic acid. It is found free in the sweat and as a triglycerid in butter ; it is also met with in the fseces and urine, in the juice of muscle and of many glands, and in various kinds of decomposing animal and vegetable matter. Pathologicalhj it appears in the free state in the stomach, urine, blood, fluid of ovarian cysts, and in the sputa in gangrene and bronchiectasis of the lung. It occurs in the organism together with lactic acid, in consequence of putiid fermentations of starches or saccharine bodies. Butyric acid is a viscid liquid that burns with a blue flame, and is easily soluble in water, alcohol, and ether, calcic chloride separating it Irom its solutions as an oily liquid. It is precipitated by sulphate of copper and hydrate of baryta, and gives a yellow precipitate with niti'ate of silver (C4H7Ag02), and salts of lead and zinc also coml)ine with it. VALERIANIC ACID is often jjresent in the faeces and is an oily liquid. Valerianate of ammonia is produced in the putrefaction of 40 NUTRITIOX AND FOODS. iiupuro leucin, :uul accordingly it may be met with in the urine in acute atrophy of the liver, and in typhus and variola. CAPROIC ACID is an oily fluid contained in butter ; it occurs in fieces after a meat diet, and is occasionally also to be found in sweat. It is pi'oduced, together with other acids of the fatty series, by the oxidation of albuminous substances and of the higher fatty acids. The palmitic and stearic acids are insolul)le in water, readily soluble in ether, chloroform, or hot alcohol, soluble also in glacial acetic acid. They enter into the composition of nearly all vegetable and animal fats, forming glycerides, and combine with the alkalies to form soaps, the latter generally consisting of mixtures of the potash and soda suits of these and other fatty acids, the soda soaps being known as the hard and the potash soaps as the soft soaps. PALMITIC ACID (C,gH3,C0.0H) is a colourless solid body, crystallising in beautiful white needles, or in masses of crystalline scales when it cools after having been melted. It forms three ethers or palmitins — monopalmitin, C3H.5 - ) ^ ; dipalmitin, I OTT C3H5 TT r\ \ > ^^^^ tripalmitin, C3H.5(CV,H3,0^)3. Palmitic acid is occasionally met with in decomposing pus, cheesy tubercle, and sputa in gangi-ene of the lung, STEARIC ACID is the chief constituent of the more solid animal fats, as suet and the like ; but it is also abundant in the softer fats, as in human fat and butter. It crystallises in lai-ge glancing scales, and, like palmitic acid, it forms stearic ethers or stearins. It is generally found mixed with palmitic acid, though this latter may be chiefly present, as in palm oil, but they can be separated by dis- solving the mixture in hot alcohol and adding to this an alcoholic solution of acetate of magnesia; magnesic stearate crystallises out, which can then be decomposed by hydrochloric acid. By heating the separated stearic acid again with hydrochloric acid, and crystal- lising it sevex'al times from alcohol, the stearic acid can be obtained in modeiate purity. II. Of the glycollic series we shall only refer to LACTIC ACID, C;,IIc03, which forms a syrupy colourless liquid, soluble in water, alcohol, and ether. Two or three of its four isomeric modifications exist in tbe body. As etJiylidene-,ferm(:ntation-, or iso-ladic acid it is ob- tained in lactic acid fermentation, and the same form is met with in the intestinal tract, occurring also in many glands and in ganglionic nerve cells. El hi /lew, lactic add generally accompanies elJddene-, para-, or narcolactic acid in the watery extract of muscle, but with regard to CHEMISTRY OF THE ALCOHOLS AXJJ FATTY ACIDS. 41 its presence there is still some douht, although it is saiJ to have been found also in cortain pathological exudations (Wislicenus). The sarcohictic acid appears in muscles, especially after prolonged activity, also in the hepatic cells. It differs fi'om ordinary lactic acid in polarising light largely, the free acid being dextro- and the anhydride Iievo-i'otatory ; and in its salts crystallising differently, and with a smaller proportion of water. Abnormally lactic acid is met with in the blood, particularly in leukaemia, pyaemia, puerperal fever, and mny show itself in purulent discharges, in the saliva in diabetes, and in the urine, especially after phosphorus poisoning, in acute atrophy of the liver, leukoemia, and tricliiiiosis. and occasionally in osteomalacia and rickets. Preparation. — Dissolve cane sugar, 3 kilo., in 13 litres boiling watei', and add 13 grams tartaric acid; and after several days mix with this 4 kilo, sour milk with which has been stirred up 100 grams old cheese and 1'5 gram carb. of zinc. Leave for eight days at 30° to 35° ; collect the deposit of lactate of zinc and crystallise it out of hot water ; dissolve it up again in boiling water, and ])ass a current of sulphuretted hydrogen through the solution. The filtrate is then to be evaporated to a thin syrup and shaken up with ether, and the ether extract distilled off over a water bath. (See the preparation of sarcolactic acid under Muscle.) L:Tctic acid is possibly a derivative in the organism of sugar : C,iHi^O(j=2(C3Hg03). Its decomposition into carbonic acid and water is easily effected in the sy.stem, although it may at iirst be split into butyric acid, carbonic acid, and hydrogen (Hoppe Seyler). A watery solution of lactic acid, when exactly saturated with caustic soda, will after some time again show an acid reaction. A similar solution also possesses the property of suddenly diminishing in its specific rotatory power on light when diluted, this gradually rising again, but never to its original amount. If boiled with carbonate of lime, lactate of lime, 2[{G3H.r,O3)2Ca] + 0H2O, separates in tufts of fine needles. Lactate of zinc, Zn{C.^\li^0^)2-\-?>a'fi, is obtained in crystalline needles or crusts ; it is insoluble in alcohol, but is slightly soluble in water, the paralactate being much more soluble than the ordinary lactate. It also forms little silky needles when boiled with carbonate of silver ; this silver lactate is almost insoluble in cold, but easily soluble in hot alcohol, and if long boiled the alcoholic solution takes a blue colour. III. Of the oxalic series we shall describe the two following : — OXALIC ACID, C.,H204 or {COOHj(COOH), only exists in the body ill a combined form, principally as oxalate of lime (CaC204). The characters of this body are given under urinary deposits. In 42 NUTRITION AND FOODS. this form also it exists ready formed in many plants, often separating out of their juice in microscopic octohedral crystals, and after the use of these vegetfibles it may appear abundantly in the urine. It is also abundant in the urine in chronic catarrh of the bladder and in different mucous inflammations, and occasionally it is found in the mucous membrane of the gall bladder and uterus. It is possibly held in solution in the urine, before being deposited, by the urates and acid sodic phosphate (Neubauer). But oxalate of lime can also be built up in the organism. An injection of urates into the blood increases the oxalate of lime in the ui-ine, so that it is possiljle for the oxalic acid to ox'iginate in the organism from uric acid ; but under normal conditions, when active oxidation is going on, oxalic acid rarely appears, being burnt off to carbonic acid and water. An oxalate to which a little powdered black oxide of manganese is added, then a little water and a few drops of sulphuric acid, evolves carbonic acid. SUCCINIC ACID, H2C4H4O4 or | ch'cO Oir""^* '^ ^'''''''^ in the spleen, thymus, and thyroid; occasionally in urine, especially after eating asparagus and the malic acid of fruits ; also in the fluid of echinococciis cysts, and in the serum of hydrocele and hydro- cephalus ; Meissner has met with it in the blood and saliva, and in the free state it may appear in the stomach and in active muscle juice. When oxidised by nitric acid, all the acids of the fatty series, from the butyric upwards, yield succinic and other similar acids. It crystallises in large I'hombic tables or prisms, occasionally form- ing prismatic needles or hexagonal plates ; and is soluljle in 3 parts boiling and 17 parts cold water, less soluble in alcohol, and insoluble in ether; it begins to sublime at 120°, melts at 180°, and decomposes at its boiling point, 235°. Succinic acid is formed by the oxidation of many organic sub- stances, especially the fatty acids, and it may possibly be a derivative of proteid decomposition. Ferric chloride gives with it a brown Hocculent precipitate ; and it is also precipitated by neutral acetate of lead, and by salts of silver and mercury. IV. Only two other bodies will be here described, to complete this very cursory sketch of the alcohols and organic acids — namely, oleic acid and plienol. OLEIC ACID belongs to the acrylic series, of which the gene- )-al formida is II{C„IT2„_3)02. It is monobasic, IlOj^ilIgaO.j or C'igHagO.OH. Wlien heated with caustic potash it breaks up thus: C,„H:,,,0.^-|-KIiO=(J2H3X02 (potassic acetate) +C,(;H3,K02 (potassic palmitato)-|-H2. This acid is found in all the fats of the body, and is present also in most natural fats and non-drying oils. It CHEMISTRY OF THE ALCOHOLS AND FATTY ACIDS. 43 forms a clear oily liquid that is insoluble in water, but readily solulde in alcohol and ether, and crystallises in white needles which melt at 14°. Like the palmitic and stearic acids it forms three glycerides. By heating it we obtain silky needles of sebacic acid (CigHiyO.,) ; and it forms a neutral oleate wdth lead, which is distinguished from the plumbic salts of the other fatty acids by its solubility in boiling alcohol. PHENOL (Carbolic Acid, Phenic Acid), Cjr.O or CgHsOH, belongs to the benzene group, CuHg. This body is produced in the dry distillation of coal, forming the chief constituent of the acid part of crude coal-tar oil ; by the dry distillation of salicylic acid it is also readily prepai'ed. The urine of the horse and cow normally contains it, and in human ui-ine it is present after the administration of benzine. It seldom presents itself in the urine in the free state, but frequently as phenyl sulphate (C,.II,,0S03H) and hydrochinon [CoH4(OH)2]. The dark colour of the urine after the ingestion or absorption of this acid is probably due to the oxidation of the hydrochinon or its isomer, brenzcatechin, derived from it (Baumann). Under normal conditions the amount present is very slight, but it is increased in certain diseases, especially those where the intestinal contents are retained, as in ileus, though it has also been found even in cases of diarrhoea with rapid decomposition of the intestinal con- tents. Part of the phenol at least is probably derived from some of the decomposition processes occurring to the proteids in the intestine. It forms a colourless, oily liquid, boiling at 183° and solidifying at low temperatures, crystallising in large colourless prisms which fuse at 37-5° ; its solubility in water is very slight (1 : 20), but it is very soluble in alcohol, ether, and potash. To detect the acid in the urine this liquid should be distilled after the addition of some alkaline carbonate, and the tests can readily be applied to the first portions of the distillate. Tests and Properties. 1. Perchloride of iron gives with it a deep violet colour, which quickly changes to a dirty brown, 2. A chip of fir or a deal shaving moistened with a watery solu- tion of carbolic acid, then ])lunged in dilute hydrochloric acid and exposed to the light, is tinged of a deep greenish blue. 3. Nitrate of silver is reduced by it, and it is transformed into picric acid by long boiling with strong nitric acid, oxidising \\dth violence and forming a red solution, which on cooling deposits yellow crystals. 44 NUTlilTIOX AND FOODS. 4. Add to a wateiy solution quai'ter its volume of ammonia, then some th-ops of po^rt.«^i?{Mt chloride solution (1 : 20), and warm gently ; ;i beautiful blue colour will soon appear, or, if the solution is very dilute, the colour will be more or less greenish. 5. Gives a blue coloration in presence of a little anilin and an alkaline solution of sodic hypocldorite ; this is a very delicate re- action (Jacquemin). 6. A dilute watery solution gives a yello\vish white crystalline precipitate of tribromphenol (CQH2Br30H) with bromine ii'ater. Salicylic acid gives a simihir precipitate, so that in testing urine for carbolic acid in presence of this acid we should neutralise with car- bonate of soda and shake up with ether, which removes the phenol. This method may be employed in the quantitative determination of carbolic acid, 331 parts of the bromine being equivalent to 94 of the acid. 7. Boil a little very dilute solution Avith Millon's reagent, and an intense red coloration is produced. 8. Add a little carbolic acid to yellow nitric acid or to a solution of potassic nitrite (6 per cent.) in strong sulphuric acid, and a brown coloui' is jDi'oduced, changing to a green and then to a blue. CHAPTER IX. CHEMISTRY OF THE CARBOHYDBATES. To the carbohydrates belong the starches, dextrin, and sugar. They may be thus grouped: — III. Amylases. I. Glucoses. Grape sugar, or dex- trose Galactose Inosit LcX'Vulose, or sugar of fruits ir. Saccharoses. riane sugar Lactose, or sugar of milk Maltose Arabin (in gum ara- bic) Starch Dextrin Glycogen Cellulose Granulose The glucoses are regarded by some authorities as the alde- hydes of the natural sugars or hoxhydric alcohols, mannite and dulcite, the former present in niaiiiin, an exudation from a species CIIEMISriiY OF Tin: CAJlBOIirnitATE.S. 45 of ash, and in llic sap of llic api)!^ and clieny, and llio latter in tlic bellies of i lie inomitain ash. These two bodies liave the coini)osition C,3Hy(()H)g, but they do not ferment or reduce an alkaline solution of a cupric salt. Ey the action of nascent hydrogen grape sugar is converted into inarnite, and by acting in the same way on inverted milk sugar dulcite has been ob- tained. Of the diglucosic alcohols or saccharoses, 2CgH]20g — HgO — ^12^22^^!' ^^'^ have examples in cane and milk sugar. Further, there are anhydrides of the glucoses (CgH,205 — H2() = C,;H, ,,(),), or the so-called amyloses. They all belong to the carbo- hydrates, as they consist of 6 or 12 atoms of carbon united with hydrogen and oxygen in the proportion in which they form water (H,0). STARCH (Fecula, Amidin), viCgHioO,, or, taking n = 3, then Ci^HgjjO,-. This body is most widely diffused throughout the Fk;. C— Stakch Granules, a, potato starch ; 6, potato starch higlily magnified ; c, wheat starch, rings not so well marked as in the potato ; d, rice starch, very small and angular. vegetable kingdom, being found in nearly every plant, and as a rule most abundantly in certain roots and tubers, soft stems, and seeds. It appears as a white glistening powder that is made up of little rounded transj^arent bodies or granules, each of which has a central spot or hiluni around which are a series of depressed more or less parallel rings. These granules vary in appearance according to their source. Each granule consists of an outer layer of cellulose enclosing alternating layers of granulose and cellulose. A variety of granulose present in small amount and giving a red colour with iodine Brucke has named erythro- granulose. Starch is nearly insoluble in cold water and most liquids. When it is boiled with water the granules of which it consists burst and disappear, but even with much water the starch is 46 XUTJilTIOX AXn FOODS. chiefly suspended as a colomles;? jelly, only a small proportion being in solution. Conversion of Starch into Sugar. — Make a thick, gelatinous, starchy solution, and add to it a little lukewarm watery infusion of malt ; heat the mixture to about 70°, and in a few minutes the thick, gelatinous starch gives place to a thin fluid con- taining dextrin and glucose. The infusion of malt acts by virtue of the presence in it of the ferment diastase ; the tem- perature must not, therefore, rise as high as 100°, or the fer- ment will be rendered inactive. When starch is converted into sugar by the action of acids or diastase, dextrin and glucose are formed simultaneously (MuscuLUs) : C,8H3oO,g + H20=:Cf.H,206 4-2CgH,o05. The dextrin obtained by the action of saliva on starch Brucke regards as a mixture of erythrodextrin, coloured red by iodine, and achroodextrin, which is not coloured, and is possibly not converted into sugar at all, or if so with difficulty. Leuchs first demonstrated the conversion of starch into sugar hy means of saliva, the active principle of which is ptyalin, 1 part of this body being capable of converting 2,000 parts of starch into sugar. Eaw starch is more slowly acted on than starch that has been cooked, raw maize starch, however, being changed in a few minutes, but raw potato starch very slowly ; and all starches are not affected alike, for boiled potato starch is more easily converted into sugar than boiled wheaten starch, and this in turn more quickly than rice starch (Lefbehg). Further, the cellulose is not so readily, if at all, converted into sugar by the saliva as the granulose ; therefore when the cellulose coats are ruptured by boiling the granulose is more easily acted on. Starchy substances to serve as nutriment must first undergo this change into glucose by the action of animal diastase, a fer- ment fcjund not only in the saliva, but also in the pancreatic and intestinal juices ; its digestion, accordingly, commences in the mouth, where a certain amount of sugar is formed ; it also continues in the stomach, but to a less extent, on account of the acidity of the gastric juice, the presence of albumin, however, not interfering with the conversion in any way (Mialiie), although it affects the reducticm of cupric oxide when the copper test is employed to detect the presence of the sugar. CIIEMISTnY OF THE CARBOHYDRATES. 47 In the siiiall intestine tlie diastatic conversion occurs with renewed energy from tlie afflux of the fresh ferment of the pancreatic and intestinal juices, the acid reaction at the same time gradually disappearing. Starch is a colloid. 2^o fit it for (ihsorption It ranst therefore he chamjed into suyar. Take two large glass tubes about 3 inches wide (students may also make use of small funnels), and tie very firmly a piece of moist parchment or of the large intestine of a sheep over one end of each ; then, having nearly filled them both with water liolding some cooked starch in suspension, and added to one of them a little saliva, fix them vei'tically in two dishes. Lay tliem aside for 12 hours in a moderately warm place ; then test the fluids that have transuded with iodine and Fehling's solution (see p. 64) : sugar will be detected in the fluid that has come from the tube to which saliva was added, but no starch will be found in either transudation. Starch, therefore, is a colloid, and does not pass through animal membranes, whilst sugar readily does so ; and the sugar in this ex- periment has been derived from the conversion of some of the starch by the saliva. Tests. — 1. Add tannic acid to a solution of starch : a yellow precipitate containing tannic acid falls down, which redissolves on the application of heat. 2. Free iodine forms a deep indigo-blue compound with starch, but heat destroys the colour if long applied. Some dilute solution of iodine is added to a little starch mucilage (see their preparation, p. 2) in a test tube, or starch granules on a microscopic slide are irrigated with the iodine solution. This is done as follows : Spread a small pinch, say of potato starch, or a scraping of the cut surface of a raw potato, upon a slide in a drop of water, apply a cover glass, and then place a drop of the iodine solution on one side of the cover glass and a slip of filter paper close to the other side. Very soon the iodine solu- tion finds its way inwards, and stains the starch granules a beautiful blue. Before the cellulose constituent takes this blue colour it must first be acted on with sulphuric acid or chloride of zinc. DEXTRIN (British Gum) is intermediate between starch and sugar. It is the name given to the body obtained by boiling starch paste with a little dilute sulphuric or hydrochloric acid 48 yUTJilTIOX AXJ) FOODS. until the paste becomes tlun and limpid and more or less gum- like ; but if the boiling is too long continued dextroglucose will be formed. It is also obtained by heating dry potato starch up to 400°, when the latter becomes yellowish and soluble in water. Diastase eifeets the sam:e thing with starch paste, although its continued action leads to the formation of maltose. Dextrin has been fovmd in the blood and organs of herl)ivora, and LiMrRicHT has discovered it in the llesh of young horses and dogs, probably as a decomposition product of glycogen, and occasionally in the liver; Reichard found it once in diabetic urine, and it appears in the alimentary canal after the ingestion of starch. It LS a gummydike body, forming a white or yellowish powder, which is soluble in water, constituting a turbid solution, but insoluble in alcohol and ether ; it does not reduce cupric oxide (or only to a slight extent), nor does it fei'ment with yeast, but it has a strong light polarising action on light, and is readily converted by the action of dilute acids or diastase into grape sugar. With a watery solution of iodine it gives a brownish or port-irine red colour, which disap- pears on heating. Brucke, as we have seen, distinguishes two kinds of dextrin — eryfhrodextrin, whose solution is coloured of a rosy red by iodine, and achroodextrin, which is not coloured by it, and is not so readily converted into sugar, although this change may be effected by boiling it with dilute hydrochloric acid. The dextrins possess many points of resemblance to glycogen, which polarises in the same way and is similarly acted on by acids and ferments ; but while neutral watery solutions of dextrin are transparent those of glycogen show an intense white opalescence ; iodine solution also stains glycogen of a dark brownish and not of a rosy red, as is the case with dextrin. Tests. — Alcohol precipitates it from its arpieous solutions, so also does lime water, and a mixture of ammonia and basic acetate oj lead ; when boiled with nitric acid it yields oxalic acid. Its solutions give a violet coloration with a solution of iodine in potassic iodide. Boil a few minutes Avith dilute hydrochloric acid ; the solution becomes thinner, and gives the tests for grape sugar. It is distinguished froi7i starch by its amorphous shape and its red coloration ly iodine, and from glijcogen by the want of oi)alescence of its solutions and by its not being precipitated by basic acetate of lead alone. To prepare it, make 20 grams stai-ch into a paste with 30 c.c. water, and aditate the dextrin formed by the addition of alcohol ; or the sulphuric acid may be re- moved by saturation with clialk and subsequent filtration, the filtrate being eva[)Oi'ated to diyness. CHAPTER X. GLYCOGEX. GLYCOGEN, HC6H,/),[5(CgH,/).)orll(C6H,oO,),HoKMAN.\; 0,^H.,o(),. + 4H20, Ai5ELF.s]. — This body was first discovere'l in the liver by Claude Bernard. It is there built up by the liver cells, appearing as little granules or amorphous masses, its amount depending greatly on the character of the food ; one of the great functions of this organ, indeed, being its production — this occuiTing even in severe diabetes (KuLZ). The liver of young beasts is richer in glycogen than that of older animals. It is present in considerable quantity in most of the embryonic tissues, appearing to increase up to the middle period of gesta- tion, and then gradually to diminish towards its conclusion. Glycogen would therefore appear to have an important rvle to play in the development of the tissues. It is also met with in all developing embryonic cells, and in the leucocytes and pale corpuscles during their period of activity. Salomon has found it in both arterial and venous blood, and traces of it are to be met with in most of the organs, as in the pancreas, kidneys, brain, and testes, as well as in the placenta. It is constant in muscle, and in the muscles of a rabbit Nasse obtained 0'47 to 0*94 per cent., and it appears to be increased in the muscles, mostly by whatever increases the formation of glycogen in the liver. With regard to muscle Brijcke and Weiss affirm that in tetanised frog's muscles less glycogen is present than in the resting muscles, thus pointing to a consumption, probablv indirect, of glycogen during muscular contraction ; there is less also in muscle when it has passed into rigor mortis (Nasse), but, on the other hand, the glycogen is increased when the muscle is brought into a state of paralysis by the division of its nerves (Chandelon). E 50 NUTRITION AND FOODS. Preparation (DkOckic'.s Method). — llapidly dcfa[iilatt' a large ami well-l't'd rabliit about two liours after a lull meal. ()pen the abclo- ineii without delay, and having torn out the liver, cut it into a lew pieces and throw them iato a lai-ge porcelain dish containing water that is vigorously boiling. Let them lie in the boiling water a few minutes until they are (juite hard, then remove them, and after having rubbed them into a paste in a mortar return the fine pulp to tlic l)oiling water, and boil again for about half an hour, when the milky extract is to be poured ofl', and a fresh extraction made with more boiling water. So far two operations have been performed : the acti(m of the ferment has been destroyed, and a watery extract has been ol>tained of the liver; but as this extract contains albuminous bodies insola- tion, these must be precipitated. To effect this the hot extracts are to he rapidly filtered into a large beaker that has previously been inserted in a freezing mixture of snow or ice and salt, and when it has cooled hydrochloric acid and potassio-mercuric iodide solution are added to it alternately until no further precipitate occurs. The albumins are thus thrown down. Stir well and filter after five to ten minutes have elapsed, and to the filtrate add spirit until about GO per cent, of absolute alcohol is present in the mixture ; the glycogen will thus be precipitated in a tolerably pure form, Avhich will not be the case if a larger excess of alcohol is added. The precipitated glycogen is next to be collected on a filter and washed with spirit (60 per cent.) until the washings give no turbidity with a mixtui-e of dilute caustic potash, ammonia, and ammonium chloride; then with absolute alcohol, and rei)eatedly with ether. Now detach the glycogen from the filtei', and dry it rapidly on a piece of porous earthenware at a moderate heat. It should form a white powder, that may be furtlier purified, if necessary, by dissolving it in hot water and precipitating it therefrom with alcohol to which a little ammonia has been added, redi -solving as before, precipitating with spirit containing acetic acid, and washing this last precipitate with absolute alcohol and ether, and then drying it. The jxdaasio-niercuric iodide is prepared by carefully precipitating a saturated .solution of potassic iodide with one of mercuric chloride, and having washed the I'esulting precipitate, making a saturated solu- tion of it in some hot solution of potassic iodide. JJifierent other methods have been proposed, such as the use of caustic pot'ish and acetic acid to separate the all)niiiin, but the author much prefers Bruckk's to any of them. It should ])e remembered that wherever glycogen is mot with in the body a diastatic fei-ment can also be obtained, so that in the prcjiaratiou of gl}cogen this should GLYCOGEN. ol he guaiilod against, as otherwise uuich of the glycogen may ))e con- verted into sugar if the action of the ferment is not destroyed. Properties. — It is a white or yellowish white, tasteless, inoflorous, and ainori)]ious ])ow(ler, that is insoluble in alcohol or etlier, but fonniiiii^ an imperfect opalescent solution in boil- ing water, which polarises to the right about three times as powerfully as does grape sugar. In many of its properties it corresponds to dextrin (see p. 48), and when a glycogen solu- tion is boiled part of it is changed into a dextrin-like body. Sources. — (jlycogen is very abundant in the liver after ingestion of starch and sugar, this organ, however, being com- paratively poor in it after a diet of fat and albumin; but the formation of glycogen does not appear to be directly de]^)€ndent on the presence of carbohydrates in the intestine ; it rather seems to be an intermediate decomposition product of albumin in the organism (Wolffherg, &c.) It ought to be remembered in discussing the different ex- periments, and the deductions therefrom as to the action of various bodies in increasing the formation of glycogen, that it does not necessarily follow that the body thus introduced becomes directly converted into glycogen, but that it may merely contribute indirectly by protecting the glycogen from change (TiEFFENBACH, &c.) And, indeed, for this very reason, and although the increase in glycogen is not so great after an albu- minous diet, many authorities regard the carbohydrates as not going directly to the formation of glycogen, but as contributing indirectly thereto by saving albumin by their own combustion, and thus allowing more of this body to remain to be converted into glycogen. It is probable that one of the great seats of urea formation is the liver (Cyon), and in diabetes we find the excretion of urea to be also increased, pointing to the pro- bable decomposition of albumin in the liver into sugar or glycogen and urea. The proteid may also split up in the liver into glycogen and the biliary acids, or its glycocin derivative may split into urea and glucose (4C2H-N02 = 2COX2H^-fCgH, 20s). The formation of glycogen in the liver, as well as the separation of sugar, can be markedly influenced. Thus punc- ture of the floor of the fourth ventricle at the point of the calamus scriptoriuis after a short time causes sugar to appear 52 NUTRITION AND FOODS. in the urine. And that the liver is concerned in this is seen from the fact that if the liver contains no glycogen (as after long fasting, or when its glycogenic activity is destroyed by arsenical poisoning) no sugar appears in the urine after the experiment (Luchkinger). The state of the vasomotor nerves of the liver appears to exercise considerable influence on the formation of sugar. It is probably by their action on these nerves that such bodies as curara, amyl nitrite, ether, and chloral hydrate act in causing sugar to appear in the urine. It would appear therefore that diabetes is really a disease of the nervous system ; but even in this disease the liver does not appear to have lost its power of forming glycogen out of sugar. The assimilation of starches, sugars, inulin, glycerin, albu- min of egg, fibrin, and casein causes an accumulation of gly- cogen in the liver, while inosite, quercite, mannite, glycocin, gums, and fats fail to do so (Mering, &c.) While Bernard obtained an increase of glycogen with a flesh diet, very little increase has been obtained by feeding animals with fibrin (Dock, Luchsinger) ; but Fints", Mering, &c., caused its increase upon a diet of flesh or egg albumin, as well as of blood fibrin. Wolffberg, by feeding an animal with 8 grams albumin and 60 grams sugar daily, obtained 0*474 gram gly- cogen ; with 30 grams albumin and 60 grams sugar, 0*821 gram glycogen ; and with 50 grams albumin and 60 grams sugar, 1'84 gram glycogen in the liver. Forster, by an injection of glucose into the portal vein, also increased the glycogeA. Hunger is very slow in diminishing the glycogen in the liver, six days at least being required to reduce it to a minimum. It is also much exhausted by fevers. KiJLZ found that in fast- ing animals starch and sugar caused glycogen to appear in the liver ; further, that severe exercise reduces this practically to nothing, and that five or six hours' exercise will produce a result that can otherwise be obtained only by starving the animal for twelve to twenty. days. Destination. — Glycogen must be regarded, however derived, as a store of carbohydrate material, which is used up according to the needs of the economy. GLYCOGEN. C;5 JjERNAKD believes that a continual conversion of this body into sugar is going on in the liver, and that the sugar formed is carried thence into the circulation, to be burnt up in the lungs and tissues generally, but particularly in the muscles. The quantity of sugar in the blood is small but constant, and, as it is constantly being used up by some of the tissues, it is possible that the supply is maintained by a regulated conver- sion of the glycogen. The blood of the hepatic vein is rich in sugar (Bernard), though this is denied (Pavy) ; but even a difference so slight as to be almost impossible to detect chemi- cally might be sufficient to account for a complete conversion of the glycogen of the liver into sugar if the rapid circulation of the blood is taken into account as well as its large volume (Flugge). The conversion of glycogen into sugar takes place more rapidly when the circulation through the liver is accelerated ; and this undoubtedly occurs in certain lesions of the nervous system (Bernard, Cyon), in which the vasomotor centre in the medulla is destroyed, or the vasomotor nerves of the hepatic vessels divided in any part of their course, so as to increase the circulation in the li\er. ►Such a conversion of the glycogen, however, is said not to occur during life under normal conditions, it even being affirmed that instead the glycogen becomes a source of fat, being merely a preliminary stej> in the metamorphosis of sugar into fats (Pavy) — an hypothesis that may be probable, but which cannot be regarded as well founded. McDoNNEL is of opinion that the glycogen unites with the nitrogen set free by the disassimilation of fibrin and albumin, so as to constitute a protein compound resembling casein. Conversion of Glycogen into Sugar. — This, as we have just seen, is what normally occurs in the body under the influence of certain ferments found in the liver as well as elsewhere in the organism, the change being proportioned to the wants of the economy. It has been abundantly proved, for example, that the liver contains an active ferment capable of effecting this con- version. Experimentally it can be shown that the change i.s readily produced, the presence even of traces of soluble albu- min lieing ca|)able of loringing it a1)out, though the process is 64 NUTIilTIOX AXD FOODS. very much slower than under the influence of the diastatic ferments contained in saliva or pancreatic juice (Seegen). A pure glycerin solution of glycogen apparently only requires the addition of water to render it capable of fermentation. But it would ajjpear that the product of the action of the animal diastase is a mixture of achroodextrin and maltose, only very little dextrose being formed (MuscuLUS and jMering). Experiments. I. To Demonstrate the Prese/bce of Sit(jar in the Liver. (The pre- sence of glycogen has already been demonstrated in its preparation.) — Feed a large rabbit, and when it is in full digestion decapitate it ; then, Fig. 7.— PiiKssuRE Buttd: «, the large bottle into wliich water flows from a water tap c ; t, a U tube containing mercury in its beiiil, acting a^ a i)ressur.; gaugje ; il, tube to be connected witli a wash bottle like b iu fig. 8. Tlic glass cannula for inserting into the vessel is figured to the right. having opened its abdomen, look for the portal vein, and tie a glass cannula in it. The liver is next to be gently removed, taking great care not to tear it, and to be placed in a large deep porcelain dish. (The experiment may likewise be performed, and even more advan- tageously, without removing the liver at all.) Another glass cannula is now fixed in the hepatic vein, and the cannula in the portal vein connected with a pressure bottle. In making \hc. connection cai'C ma-st be taken to exclude air by (iliiiig llic cannuhi IVoni the bottom a LY CO a F.N. 65 by means of a long capillary pipette. Now turn on a pressure of 2 to 3 inches of mercury, and wash out the liver, collecting at intervals a portion of the washings as they pass through the cannula in the hepatic vein in a series of small beakers that are to he labelled 1, 2, 3, 4, ttc. Test each of these for grape sugar with Fehling's solution, but it is generally advisable first to separate the albumin present by boiling after the addition of a drop or two of acetic acid. Sugar will be found in a diminishing quantity in each of the specimens, until its presence can no longer be detected. When all the sugar has thus been washed out, lay the liver aside for some time, and then repeat the process : sugar will again 1)6 found. This sugar, ac- cording to Seegen, is tiue grape sugar, wdiilo that formed by the action of the salivaxy and pancreatic ferments on glycogen is not true grape sugar, but an allied form. The pressure bottle is easily constructed as fol- lows : Take a very large bottle and stop it with a good cork. In this cork bore three holes, one for a glass tul>e that will reach to the bottom of the bottle, an d wdiich is to be connected by its upper end by means of an indiarubber tulie with one of the pipes of a water supply or tank, such as are to be had in every laboratory; the second, for a short tube to be con- nected witli a U tube containing some mercury and fixed on a stand ; and the third, for another short tube just passing through the cork, its upper end having attached to it a piece of rubber tubing. This last is to connect the pressure bottle with an ordinary wash bottle. To obtain tlie pressure the plan may also be adopted of suspending a large bottle filled with water over a pulley. In an aperture near the bottom of this bottle is fixed one end of a long piece of llr^xiide I'ltE.-tl i;i. Ewi iLi:. a contains water and is suspended by a cord tliat liassts over the pulley e, and is fastened at rf ; 6 is tlie pressure wash bottle ; c is the vertical support for the pulley ; its front edge is graduated in inches. 60 NUTRITION AND FOODS. tubing, tlic otlier cud being conncoted witli the pressiire bottle. This suspended bottle can be raised or lowered as required b}^ means of the cord attached to it, and if a gi'aduated scale is placed lieside it the degree of pressure can be read theiefrom, and the U mercury tube I'cndered unnecessary, II. To Prejjare the Ferment. — Place a large piece of the above liver, or better of a liver just removed, which has been minced nnd washed in water to remove the blood, in some strong spirit for a few minutes; then I'cmove it, and having dried it, cut it up into very small fragments, that are to be immersed in absolute alcohol and laid aside for 48 hours. When the alcohol has been filtered off, and the mass well washed in more of the same, place it tinder strong glycerin for a week. The glycerin extract is then to be filtered through muslin. A similar ferment can be prepared from bile by treating it with alcohol and extracting with glycerin as above. III. Tests and Reactions. — 1. Test with a solution of iodine made by placing a little fragment of this body in water, and then adding finely powdered potassic iodide with constant stirring until a wine-red solution is obtained ; fresh glycogen solutions give a deep vinous red, and the dry powder a chestnut brown tint. The colour disajjpears on heating the solution, but returns on cooling. Dextrin gives a somewhat similar reaction, but the colour does not reappear when the liquid cools. 2. Add caustic potash and a drop or two of cupric sulphate solution : a blue solution is obtained, but on boiling no reduc- tion of the cupric oxide occurs. 3. Boil a little glycogen solution witli a few drops of dilute hydrochloric acid : sugar is formed, which can be detected, after neutralisation with caustic potash, by boiling with a little Feh- ling's solution, when a yellowish precipjitate is obtained. 4. Add to the glycogen solution some glycerin extract of liver ferment, and warm for a short time to 45''-50° : sugar is rajiidly formed, which can be detected as in the previous test. The presence of free acids, alkalies, alkaline carbonates, or sodic silicate interferes with the conversion. The glycerin extinct acts equally well with starch mucilage, but if the extract is boiled its ferment action is destroyed. 5. Place some glycogen solution in tliice test tubes, ;ind add to one of tlicm a lilt Ic bloofl. mid t(j another a liMU' saliva; GLYCOGEN. 57 lay the three lul)es aside for about twenty minutes at a tempera- ture of 37°, and then test them for sugar : this will be found in the tubes to which the blood and saliva have been added, but not in the third. A ferment must, therefore, be present in the blood and the saliva of the same nature as that contained in the glycerin extract of the coagulated liver. 6. A watery solution is precipitated by piumliic acetate, thus differing from dextrin, but, as with dextrin, a precipitate is thrown down by plumbic acetate and ammonia. CHAPTEli XI. CAXE Si'GAB, LACTOSE, AXD MALTOSE. CANE SUGAR, C,,>H,20,,, is generally distributed through- out the vegetable kingdom in the juices of plants, trees, and fruits. It forms transparent, colourless, rhomboidal prisms that are very soluble in water, the solution polarising to the right (73*8°). In its decompositions it resembles grape sugar and it forms combinations with many alkaline and earthy salts. Though closely allied to grape sugar there are many points of distinction : thus it is not directly fermentable, being first resolved, under the influence of yeast at a warm temperature, into dextrose and levulose, which then enter into fermentation. When boiled with dilute acids it is likewise resolved into these two bodies. Cane sugar does not reduce Fehling's solution, nor is it precipitated by basic acetate of lead, although it is preci})itated by amnionic lead acetate. Strong sulphuric acid chars cane, while it dissolves grape sugar. Jjefore cane sugar leaves the alimentary canal by absorption it most probalily first undergoes conversion into grape sugar. This conversion is generally completed before it passes the ileum, much cane sugar being found in the upper part of the small intestine (Kobner). When it is injected into the veins of an animal it is excreted in the urine without alteration, 58 NUrRITIO^' AND FOODS. which is not the ca>;e with grape sugar, and accordingly cane sugar is not directly assimilable, but must undergo a previous conversion into grape sugar. LACTOSE, or SUGAR OF MILK, C,,!!.,^),, + H,0.— How this body is formed, whether from grape sugar or by a decom- position of albuminous bodies in the organism, is still doubtful. It is found, with any degree of certainty, only in milk, although it has been described as occuiTing in the urine of women in the early days of lactation and after ' weaning.' Properties. —Lactose closely resembles cane sugar, but it is a more stable body. It crystallises in right rhombic four-sided prisms that are hard and white or nearly colourless, but it is not so soluble as the other sugars ; thus it dissolves in six parts cold and two and a half parts hot water, and is insoluble in absolute alcohol and ether, and has only a faint sweet taste. I^ike dextrose its freshly prepared solution has a dextro-rotatory power (93*1°), that diminishes slightly on standing, its warm watery solution polarising to the right 58"2°, rising to 59"2° when boiled ; but it is more or less constant at 5'2''°, independent of the strength of its solution. It is fermentable with difficulty, first, however, being changed into galactose, an isomer of glucose. When it de- composes in presence of casein it forms lactic and sometimes also butyric acid. This can be shown by adding oxide of zinc and casein to its watery solution, and keeping the mixture sometime between 35° and 40° : lactate of zinc is formed. Its compounds with bases are unstable, being decomposed readily by boiling. Acted on with nitric acid it yields mucic and saccharic (CgH,„Oj,), oxalic, carbonic, and tartaric acids. It is precipi- tated by basic acetate of lead and ammonia, and reduces alkaline cupric solutions, but less powerfully than glucose (about seven- tenths) ; so also with the other reduction tests (see under Grape Sugar), such as those of bismuth, silver, and indigo. Preparation. — 1. Add to cow's milk one-fifth its weiglit of powdered pLuster of Paris; boil aud evaporate to dryness; exhaust tlio dry residue with ether to remove fatty matter, and then treat with spirit to roiuovc the sugar present, from which it is olttainod by crystallisatioM. CANE SUGAR, LACTOSE, AND MALTOSE. 50 2. Boil ilin milk iind tlien add a fow drops of acetic or hydro- chloric acid, so as to sej)arate the curd ; filter through linen, and clarify the whey when cold by mixing with it a little well-beaten white of Qgg and then boiling the mixture ; filter again through linen or muslin, and evaporate the filtrate to a syrupy state; lay aside in a cool place for a few days, and purify the crystalline mass obtained by boiling it with animal charcoal ; then recrystallise. 3. Acidulate so as to precipitate the casein, filter through linen, boil the filtrate, and filter again ; evaporate finally to a small bulk, and lay aside to crystallise. To Detect Sugar in Mill: — Acidulate slightly with acetic acid, boil, and filter, and test the filtrate with Fehling's solu- tion and witli bisniuthic nitrate solution (see under Grape Sugar). MALTOSE is the end product of the action of diastase on starch, and can also be formed by tlie action of dilute sulphuric acid on the same body. It resembles cane sugar in many respects, but, unlike it, maltose possesses the power of reducing an alkaline solution of cupric hydrate, its reducing action, how- ever, being about one-third less than that of dextrose, but it has a stronger dextro-rotatory power than this body (150°), and, like it, is capable of undergoing alcoholic fermentation ; it can also be converted into dextrose by being warmed for some time with a dilute acid. It is said to form fine acicular crystals. Under Digestion reference will be made to the probability of this body being the chief sugar formed by the action of the animal diastase on ferments. AEABIN is the main constituent of gum arabic. When heated with dilute sulphuric acid it yields a crystalline sugar, arahinose, that is isomeric with dextrose, like this body reduc- ing an alkaline solution of cupric hydrate and polarising to the right, but more powerfully ; unlike, however, in being incapable of fermentation with yeast. 60 NUTRITIOS AMJ FOOLS. CHAPTEE XII. GRAPE SUGAR. C ... 3G-36| GRAPE SUGAR {Dextrose),Q^^,.p^^ H,0 = H ... 7-07 ; O ... 56-57J C ... 40-0 \ CgH,20g = H ... 6*6 . — Its rational formula may be written ... 53-34] C5(0CH)Hg(0H),, or GR.fiYL{CROK)^COll. In some respects, we have seen, it corresponds to an alcohol, and in others to an aldehyd. This sugar is found in the chyle after the ingestion 01 starchy or saccharine food, in the blood, especially of the hepatic vein, in the lymph, muscle juice, and in the intestinal contents. According to Bernard in the blood of the carotid of dogs it forms O'llO to 0"151 per cent., and in that of the jugular 0*067 to 0*125 per cent. In the blood of the carotid Abeles found 0-049 per cent., and in the venous blood of the right heart 0*054 per cent. The estimates given by different experimenters of the comparative amounts of sugar in the blood of the portal and hepatic veins vary considerably, some corresponding more or less with Bernard's results, and others differing therefrom. So also with regard to the proportion of sugar in the blood of the right and left heart, but careful experiments point to the proportion of sugar in the right heart exceeding that in the left rLrsK, &c.) Properties. — Pure glucose does not crystallise well, some- times appearing as little warty masses, or as little clusters of fine needles, or of radiating rhomboidal lamelhe, or in six-sided tables or prisms, occasionally also in cubes or square tables. The crystalline modification passes readily into tlie amorphous form when its solutions are boiled or allowed to stand for some time. Fi'om hot absolute alcohol it ciystallises in wliite anhy- drous needles that are closely packed in little warty masses. It is not so sweet as cane sugar, easily soliilili- in water, liut less so than cane sugar, very slightly soluble in alcohol, and insolu))!e in etlier. Its watery solutions polarise strongly to OR.IPE SUGAR. 01 Hk; riirlif : ■'>o'\° ( ToLLKXs), or the crystalline form 00-4", 'an) From Diahpfic Urine. — Evaporate the urine at a low tempera- ture to a syrupy consistence, and at the end of a few days or weeks an abundant crystallisation appears. Decant and rub up the saccha- rine mass with a little alcohol, treat it with more spirit, and decant again ; then boil with still more alcohol, filter, and allow the filtrate to crystallise. By repeated crystallisations from alcohol the sugar can be obtained free from colour and in the form of four-sided prisms, sometimes united in warty masses. (c) From Starch. — Boil the following mixture for 4 or 5 hours : potato starch 15, sulphuric acid 6, water 60. Then neutralise with chalk, filter, and evaporate the filtrate rapidly to a small bulk, from which much of the colour may be removed by shaking it up with animal charcoal. The ultimate filtrate is evaporated to a thin syrup and allowed to crystallise out. ((/) From Ilonei/, of which it forms the solid crystalline portion, it may be readily prepared by washing away the fluid syrup with cold alcohol. Combinations. — It combines with certain acids and bases (as potash and lime), forming glycosates or saccharates; when, for example, an alcoholic solution of glucose is mixed with an alcoholic solution of caustic potash, the saccharate (CgH,,KOg) 62 XUTIilTlOX ASD FOODS. separates after some time, but its watery solutions give no pre- cipitates with earthy or metallic salts; only in presence of am- monia is it thrown down by neutral or basic acetate of lead, by which, however, it is then readily and completely jn'ccipitated. From a concentrated solution of grM[)e sugar saturated with sodic chloride large rhombohedric or double pyramidal crystals, having the composition 2CgH,20e f NaCl + HgO, often separate on allowing the solution to evaporate spontaneously. Decompositions. — If 1 molecule of grape sugar is mixed with 5 molecules of cupric sulphate and 11 molecules of sodic hydrate, and the mixture laid aside for 20 minutes, the copper will be precipitated completely, and the filtrate will be free from sugar (Salkowski). In alkaline solutions it has therefore a great tendency to absorb oxygen, and accordingly acts as a strong reducing ngent. Most of its tests really depend on this pro- perty. When boiled with the stronger acids and alkalies grape sugar is decomposed ; with nitric acid it forms saccharic and oxalic acids, and with dilute sulphuric or hydrochloric acids it is converted into brown substances — ulmin, ulmic acid, &c. Under the influence of yeast it ferments at a temperature from 10^ to 40°, but best at 25° to 35° (below 5° or above 45° fermentation completely ceases) — CgH,206 = 2(C2Hg()) (alcohol) + 2C0„ a little amyl alcohol, glycerin, and succinic acid being formed at the same time. A complete fermentation will not occur if the percentage of sugar is much above 15 per cent., an accumulation of alcohol also hindering the process. Grape sugar is readily convertible into lactic and even butyric acid in presence of organic bodies in a state of change, such as are to be found, for example, in the alimentary canal. By mixing with some dextrose a little cheese, decaying albu- min, or sour milk, lactic and then butyric acid fermentation will be set up, with the evolution of carbonic acid and hydrogen. When heated glucose melts, water is given off, and glucosan formed ; at a higher temperature more watery vjipour is evolved, and at about 170° it is changed into caramel. Origin, Role, and Destination. — The sugar in the body is derived piirtly from the sugar and starch contained in the food, GRAPE SUGAR. 63 but a part is undoubterlly formed in the organism itself, joar- ticiilarlv in the liver aiid in muscle, and very probably from the glycogen. Its role is chiefly that of a respiratory food, its combustion into carbonic acid and water giving out much heat ; but whether these products are direct or not it would be difficult to say ; that there are intermediate products, however, is very likely, as is evidenced by the occasional presence of aceton in the urine, especially of diabetes, and occasionally in the urine of fevers (variola, typhus, pneumonia). MiALHE was of opinion that the sugar, when it arrived in the blood, formed glycosates that were rapidly transformed, ultimately undergoing oxidation. It is probable also that it aids in the development of muscular energy. Tests. — Before trying Trommer^s test it is generally ad- visable for the student to refresh his knowledge of some of the chemical properties of sulphate of copper, and accordingly apply the following tests to a solution of that body : (j) Add caustic potash — a light blue precipitate of the hydrated oxide, insoluble in excess. Boil, and the blue hydrated oxide is decomposed, the black oxide being deposited, (ij) Eepeat the experiment, but first add some potassic tartrate ; the blue pre- cipitate is now soluble in excess, a clear blue fluid being ob- tained, on boiling which no precipitate is thrown down, (iij) Next substitute glycerin for the potassic tartrate, and note that the same result is produced as before, (iv) The same experi- ment is to be again repeated, but this time after the addition of sugar, when it is to be observed that the precipitate is soluble in excess of caustic potash, but also that on boiling the sub- oxide is thrown down, owing to a reduction of the cupric salt, (v) Perform the last experiment again, and note the influence exerted by the addition of ammonia or its salts (the chloride, urate, &c.) in preventing the reduction ; then boil for some time with excess of caustic potash, and after the consequent evolution of ammonia it will be found that the suboxide will generally be obtained (Beale). 1. Trommei'^s Test. — Add a drop or two of n dilute solution, of cupric sulphate to the solution of sugar, so as to give the mix- ture a very pale blue tint ; now add caustic potash or soda in G4 XUTIilTIOX AND FOODS. excesf : a pale l)liie precipitate of cupric hydrate is tlirown down, which immediately redissolves, a deep blue solution being formed. Heat gently, and generally befoie the boiling point is reached a reddish., orange, or yellow jrrecipitdte of the sub- oxide of copper will show itself, appearing first near the surface of the liquid. The colour of the precipitate depends on the relative proportions of the sugar and copper, with excess of sugar being yellowish and with excess of copper reddish ; but this is also affected greatly by the degree of concentration and the purity of the solutions employed, with impure solutions, as with urine containing little sugar, the suboxide having generally a yellow colour. It is much safer "to employ a little Fehling's solution in applying this test, as many liabilities to error are thus avoided. Place some of the solution in a test tube, dilute it with water, and boil ; then add the saccharine fluid drop by drop and con- tinue the application of the heat : a yellow or red sediment will soon form before boiling point is reached. The plan of boiling the urine first and then adding the reagent is not to be adopted. If albumin is present, as occasionally happens with saccha- rine urine, it is advisable to separate this body before applying Trommer's test. This is readil}' done by acidifying the liquid with a drop or two of acetic acid, then boiling for some time, filtering, and washing the Y'l'ecipitated albumin on a filter. 2. Moore's Test. — To a little of the solution add ludf its volume of liquor jjotassce and boil gently for a minute or two : a bright brown tint is acquired by the fluid. The change in colovu- will be better seen if only the upper part of the mixed liquids is heated. It is due to the formation of melassic acid, and if a little nitric acid in excess is next added, an odour like that of burnt sugar or of formic acid will be evolved. The test is wanting in delicacy. Care should be taken that the caustic potash contains no trace of lead. 8. Reduction Tests, (a) Maurnme's. — When glucose is heated in contact with perchloride of tin (SnCl^) decomposition occurs and a black compound is formed. The test may be conveniently applied thus: Dissolve some of the perchloride in twice its weight of water and filter; GltAI'E SUCrAIi. Go immerse long stii^is of any woollen malerial, such as white merino or flannel, in this solution, and then dry them over a water bath at a gentle heat ; these strips are to be kept in a bottle till required. Dip one of them in a very dilute solution of the grape sugar, and heat the moistened slip before a fire, or otherwise (at a temperature of 130° to 150°), and it will quickly assume a brownish black colour. (Jther carbohydrates, however, possess the same property. (6) Bottger's Bismuth Test. — This may be performed in any of the three ways given below ; the third, however, is to be preferred ; but no albumin must be present. (j) Add a few drops of dilute nitric acid solution of nitrate of bismuth to the solution of sugar, then render the mixture alkaline by the addition of sodic carbonate and boil a few minutes ; the bismuth salt is reduced and a grey or black pre- cipitate is thrown drown. (ij) Boil some of the grape sugar solution and saturate it with sodic carbonate in substance, then add a few gi'ains of basic bismuthic nitrate and boil a few minutes ; a grey and then a black precipitate of metallic bismuth soon appears. (iij) First prepare an alkaline solution of the oxide of bis- muth : take 5 grams basic nitrate of bismuth and 5 grams powdered tartaric acid, and place in a small flask with 30 c.c. distilled water ; now add slowly and with constant stirring some strong solution of caustic soda until a clear solution is obtained. Close the flask with a caoutchouc stopper through which passes a tube filled with fragments of caustic lime. Add a little of this to the solution of sugar and boil for a few minutes, when a marked brown and then a black colora- tion shows itself, a black powder subsequently separating. (c) Silver Teat. — Add ammonia in excess to a little strong solution of silver nitrate, then boil after the addition of the grape sugar ; the silver salt will be reduced and form a mirror in the bottom of the tube. _ Aldehyde and tartaric acid, however, give the same reaction. (fZ) Indigo Carmin. — Add some sodic or potassic carbonate to a dilute grape-sugar solution, and then sufficient solution of indigo carmin to impart a blue coloration ; boil, and a yellow colour will ultimately make its appearance, indigo white being F 6G XUTIilTIOy AXD FOODS. formed, the blue cliiinging to green and then to reddish purple and red. The Ijlue tint may be restored by pouring the fluid into a small flask and shaking in the air for some time, but the yellow colour soon reappears. 4. Picric Acid Test. — INIix with the sugar solution an equal volume of a saturated solution of picric acid, and heat the mix- ture gently after the addition of a few drops of liquor potassa?, ; a deep red broiun colour gradually appears. 5. Fermentation Test. — This is one of the most satisfactory tests for sugar, but it fails if only slight traces (below 0*5 per cent.) are present. (a) Fill a large test tube with a dilute solution of the sugar, and after adding a little dried Grerman yeast, or some fresh yeast, invert the tube over some more of the same solution of sugar, or better over a layer of mercury in a small evaporating dish, closing the mouth of the tube with the finger or with a pad of indiarubber in doing so. Lay the whole aside in a warm place (about 25°) for 24 hours. The sugar will undergo fermentation, alcohol and carbonic anhydride being formed, the latter accumulating in the test tube and displacing the fluid. To identify the carbonic acid gas, close the lower end of the inverted tube with the thumb, and transfer it to a dish cr)ntaining water ; then fill a small test tube with water, and having inverted it in the same dish, bring the mouth of the large test tube under that of the small one, so as to allow a little of the gas to escape and enter it. Test the carbonic acid gas thus obtained by the addition of clear lime water, which at once becomes milky on shaking it with the gas from the formation of carbonate ; or by passing a piece of solid caustic potash into it when over mercury, by which means the gas will be absorbed. As the yeast itself, from being impure, frequently evolves carbonic acid, as a precaution place the same quantity of yeast in another test tul^e filled with water, and proceed with it as with the solution of sugar. {h) When only a small amount of sugar is present, say in urine, the test maybe thus applied: The dilute saccharine solu- tion is acidified with a (li'op of acetic acid and a small piece of yeast well iiu'xi.'d up with it ; it is then transferred to the cylin- der a in the adjoining apparatus, so as to fill it, and then into GRAPE SUGAR. 67 the narrow part of tlie cylinder 6 some mercury is poured. Tlie whole is set aside in a moderately warm place (30"). In a few hours gas is disengaged and collects in the upper part of a. To prove it to be carbonic acid fill the wide part of the cylinder c with caustic potash ; then having closed the orifice with the finger, shake vigorously, when the gas will be absorbed. It is advisable to make a control experiment at the same time, replacing the saccha- rine solution or urine with water. To render the experiment conclusive by detecting the 'pre- sence of alcoJiol, which, how- ever, is unnecessary, the dilute saccharine solution should be evaporated to half its vobune before adding the yeast, and the fermented fluid afterwards treated with benzoyl chloride, which causes benzoic ether to be evolved (Berthklot). Or distil and mix the distillate with a little solution of iodine in potas- sic iodide ; add caustic potash drop by drop till the colour dis- appears, when it is to be laid aside for some time : a yellowish colour appears and a sediment soon forms, showing six-sided crystalline tables of iodoform under the microscope. (c) Two little flasks connected together, as in fig. 1.S, can also be used. One (a) is half filled with the saccharine fluid, 2 or 3 drops strong solution of tartaric acid added and then a piece of yeast. The gas, when generated, passes into the other flask (b), which is half filled with baryta water, by which it is absorbed and baric carbonate formed. Lay the apparatus aside at a temperature of 20° to 25°. (d) Fill a long test tube Avith solution of sugar and the yeast, and through the cork closing its mouth pass a narrow Fig. 9.— Appaeaius fou Sugar Eeiijiex- TATioN Test. Tins is to be recommenilud when the amount of sugar present, as well as of tlie urine or other fluid containing it, is small, a, cjlinder into whifh the fluid is to be passed by means of rf, the whole vessel being inclined, and in which the carbonic acid gas accumulates ; 6, a little quick- silver at the narrow communication between a and c, acting as a valve, and allowing the escape of the fluid from a to c as the gas is generated. 68 XUrRITlON ANT) FOODS. glass tube to the liottoin of the test tube. Attached to the outer end of the narrow glass tube is a piece of india rubber tubing, which dips into a small flask. Place the whole in a warm chamber at 35°. The carbonic acid generated will drive out the fluid into the flask, where it can be tested for alcohol by one of the delicate methods given under 6, or by boiling it with a little potassic bichromate and sulphuric acid, when a green coloration is produced. The Yeast Groivth. — During the process of fermentation the yeast grows at the expense of the sugar, and a characteristic delicate white scum accumulates on the surface of the liquid, which on microscopic examination will be seen to consist of torula stems and great numbers of minute oval vesicles. These granules, or torulce, are single or associated in clumps, or united end to end. Each granule is round or ^0 ^ © *^ ^ oval and transparent, having an average ^ ^ © diameter of ^ ^—^th of an inch, and con- sisting of a little thin- walled cell filled with a semifluid matter or Y)rotoplasm in which a clear space or vacuole is generally to be seen. The torulas are living bodies that under favourable conditions grow and multiply, chiefly by a ])rocess of bud- no. io.-yeast TujtLL.i:. ding, and as the result of their vitality "' ^^^tiof'acuyuj^"'""' tbe series of fermentation products are manufactured by them from the food substances contained in the fluid in which they float. The presence of nitrogen, phosphorus, sulphur, potassium, and mag- nesium in some of their combinations appears to be necessary to their growth, their development being an essential part of the fermentation process, the cells living and growing at the expense of the sugar, causing it to break up into simple substances by withdrawing from it a portion of the material necessary for their continued sustenance. Some of the by-products of the fermentation are possibly not formed by the splitting up of the sugar, Ijut are the result of some secondary action, water probably being at the same time decomposed into its elements and nascent hydrogen playing an active part. Injluenci of Acids on iJie FuriiuUlon awl Adivlli/ of Yi'.aat.—^o far as acids are concerned, fermenUition is uided by the presence of sul- GMAPE SUGAli. 09 pliuric acid 002 per cent, and of lactic acid 01 to 0-2 per cent., while it is retarded by the presence of sulphuric acid 0*2 per cent., hydrochloric acid 0*1 per cent., phosplioric acid 0-4 to 0*5 per cent., and lactic acid 2 '5 per cent. Fermentation is suppressed by sul- phmic aciil when present in the proportion of 07 per cent., hydro- chloric acid 05 per cent., phosphoric acid 1*3 per cent., and lactic acid 4-G per cent. (IIayduck). 6. The jjvesence of sugar in norTnal urine, in which it exists in very small amount, may often be shown by the follow- ing modification of Br'dcl'e's method: 200 to 300 c.c. fresh, urine are treated with excess of boiling saturated solution of chloride of lead, filtered, and the filtrate precipitated with am- monia ; the precipitate is collected, washed, suspended in water, and decomposed with sulphuretted hydrogen. It is again filtered, and the filtrate, when boiled to separate the excess of liydric sulphide, will give with Feliling's solution an abundant deposit of the cuprous oxide. 7. Precipitation by Potash and Alcohol.— By this process very dilute solutions of sugar can be tested. To a little of the dilute solution of grape sugar add 4 times its volume of abso- lute alcohol, filter after it has stood aside for several hours, and pour into the filtrate a little alcoholic (80 per cent.) solution of potash ; now set aside for a couple of days, when a deposit con- sisting of a combination of the potash and grape sugar occurs on the sides of the vessel. Drain off the liquid, dissolve the deposit in a little water, and test the solution by any of the usual reagents ; or the watery solution of the deposit may be neutralised with acetic acid, precipitated with acetate of lead, filtered, the lead separated by means of hydric sulphide, and the filtrate, which serves for the sugar tests, partially evaporated. 8. In the case of blood, chyle, &c., evaporate the serum to dryness and exhaust the residue with spirit : evaporate this to dryness, and exhaust the residue again with the spirit, which is in turn to be evaporated to dryness and its residue dissolved in water. With other fluids, or watery extracts of organs, first exhaust with spirit, evaporate the spirituous extract, dissolve the residue in water, add to this watery extract 2 or .3 drops of acetic acid, and evaporate again ; dissolve this last residue in water and apply the copper test. 70 NUTRITION AND FOODS. CHAPTER XIII. QUANTITATIVE BETERAflNATION OF GUArE SUGAIi. The amount of sugar present in a solution can be deter- mined : (1) by the polariscopo, (2) by Fehling's solution, (3) by standard cyanide of silver solution (IvNAPr), (4) by standard silver iodide solution (Sachsse), (5) by tlie amount of carbonic acid gas produced in the fermentation of a given quantity, and (6) by the alteration in the specific gravity effected by fermen- tation (Roberts). I. By Polarisation. — Before describing the process it may be ad- visable to ex{)lain the principle upon wliidi it is founded. When a ray of common light passes through certain crystals it is split into two rays, one of which undergoes ordinary refraction ; the other takes a new or extraordi- nary course, and is said to be polarised. Certain doubly refracting crystals like tourmaline tend to absorb one of these rays (the ordhianj) and let the extra- ordinary ray pass. If two similar plates of tourmahne ai-e hekl with tlieir axes parallel light passes through both, but if they are turned with their axes at right angles the light is almost entirely stopped, the light tliat has been polarised by passing through the first plate not being able to make its way through the second. Nicol's prisms, consisting of specially cut and conjoined prisms of Iceland spar, act like the tourmaline, allowing the polarised light to pass through both prisms except when they are crossed. With the pola- riser and analyser, as these prisms are named, so arranged as to allow the light to pass, a certain degree of colour will be observed, which changes in tint as the analyser is rotated. If now there be placed between the two ])iisnis thus crossed, so as Lo slop (he light., a j)l,it('i of lock crystal cut at riglit angles to the principal axis, it will l)e found that the light passes, so that the rock crystal must have rausod a certain degree of circular rotation of the polarisfd rny in its pas- sage through befor*^ it arrived at the sorond ])risin or analyser; Fig. 11.— TouinrAi.iNK Plates. a, prisms placed one bebiiid the other witli tlieir long axes parallel (light polarised by the first goes through the second unaltered) ; 6, prisms crossed at right angles (the light polarised i)y the first plate is stopped by the second, and conaplete darkness ensues). QUANTITATIVE DETERMINATION OF GRAPE SUGAR. 71 indeed, its passage through the latter prism can be interrupted by turning this prism round to a certain extent, tlie amount of rota- tion required depending on the thickness of the rock crystal and on the colour of the light employed, less rotation being ref)uirod with red than with the other primary coloui's towards the violet end of the spectrum. With some plates the rotation is towards the right hand, and with otheis towards the left. This kind of polarisation is therefore called circular, the expression rotation toioarJs the riyht being applied to a movement in the direction of the hands of a watch as seen by the observer, and rotation in the opposite direction termed left-hanthd. Solutions of many organic bodies, such as cane and grape sugar and tai'taric acid, etc., exhibit aright-handed I'otat ion, and accordingly are said to be dextro-rotatory ; while others, like a solution of albu- min, or un cry still Used sugar, and spirits of turpentine, rotate the light towards thje left and are accordingly named levo-rotatory. Suppose now the two prisms are so arranged as to extinguish the light completely, and a tube filled with a solution of grape sugar is interposed between them ; it will be found that the solution acts like the rock salt in partially lestoring the light. On rotating the analyser, or prLsm near the observer's eye, through a cei'tain angle the light is again extinguished, and it will be seen that the amount of rotation requii'ed is jointly proportional to the length of the tube holding the sugar and to the strength of the solution. As the amount of circular polarisation varies Avith the body as well as with the strength of its solution, the method can be employed in determiniiig the strength of such solutions, as in the case of the saccharimeter used for saccharine solutions. There are different forms of this instrument, but they correspond in having two Nicol's prisms so arranged as to leave a space between to receive the tube for the solution of sugar, the prism through which the light passes before entering the solution being named the polariser, and. the other the analyser, as it requires the one to produce the polarisation and the other to show it. The prisms are first crossed so as to stop the light ; the tube with the sugar is then inserted, when it will be noticed, as above explained, that the light is enabled to pass. It is then necessary to rotate one of the prisms thiough a certain angle before the light is again excluded, and this angle is measured on a circulai- giaduated disk, the })rism in being rotated carrying an index with it, which moves along the divisions on the disk. The difficulty lies in determining when the field of vision is darkest, and several additions have been made to render this more accurate. 73 NUTItlTIOX AND FOODS. The adjoining diagram •will illustrate the different parts of the saccharimeter, as well as the additions referred to. n is the Nicol's prism, or polaiiser, upon -which the light falls. */ is a layer of quartz, composed of two halves of equal thickness, one dextro- and the other levo-rotatory, their line of junction being in the axis of the instrument. if is a bi-ass tube closed at its extremities with glass, to be filled with the saccharine solution to be tested. q' is another plate of quartz, levo-rotatoiy. c, the compensator, consists of two right-angled prisms of dextro- rotatory quartz, which slide one on the other by means of a rack and pinion movement, so that the thickness of the combined plate can be altered, its effect of course increasing in proportion to the overlapping of the plates, and thus compensating more or less the effect produced by the levo-rotatory quartz plate q'. In their mean position, marked by the zero of the scale, their thickness exactly equals that of the plate q' , and accordingly they destroy its levo-rotatory action. a is the analvser. I Fig. 12. — Diagram of a SACcnARiMETER. is the ocular, consisting of two lenses, that enable the observer to see distinctly the vertical line of separation between the two halves of the double quartz plate. A scale and vernier are attached to indicate the relative position of tlie parts of the compensator, the zero of the scale corresponding to an exact compensation of the levo-rotatory quartz ; and accordingly when the screw is mov^d, so as to increase the thickness of the compensator, a dextro-rotation ensues, the contrary effect being produced by moving tlie screw in the opposite direction. Whfn the analyser is looked through two distinct colours will be seen, corresponding to each of the two halves of the quartz plate q ; but by turning the analyser on its axis the whole field can be made to assume the same tint. If now the tube t is filled with a solution of sugar, it will be found on examination that the previous uniforn-ity of the field has departed, and that a difference of c-olour shows itself, cori-esjwnding to the two halves of the plate q. Tliis is duo to the sugar, Avhich increases the action of the dextro-rotatory and QUANTirAriVE DETERMIXATIOX OF GRAPE SUGAR. 7.i diminishes that of the levo-rotatory segment — a tlifiference, however, that can be i-emoved by the I'otation of the analysci* a, or more deli- cately by means of the compensator. From the amount of screwing the compensator requires, which is read off on the scale attached, the percentage of sugar is determined; the + sign prefixed to the number indicates right-handed polarisation, and the — sign left-handed. Dififerent sacchariineters are employed. The above de- scription refers more particularly to the construction of Soleil- Ventzke's instrument. Mitscherlich's is much simpler. Saccharimetry. — Process 1. If VjG use a Mitscherlicli s instrument with a doul)le quartz plate (like q in the above diagram), the tube is placed horizontally with the polaiiser in front of the apertui'e in a cylinder surrounding a luminous flame of some kind. The analyser is then moved until the two halves of the visual field of the double plate oiTer the same teinfe de jiassage, say a reddish violet, which in a good instrument is generally indicated by the index pointing to the zero of the scale; a central vertical black line indicating the crossed position of the Nicol's is also visible. Fii-st make a solution of the sugar containing one gram to each c.c, and completely fill the tube between the prisms with this solution. ISTow look through the in- strument, and it will be found that the two halves of the visual field arc unequally coloured. Turn the analyser to the right or left until the same teinte de j^fissage is obtained as before the insertion of the sugar, and note on the scale the number of degrees corresponding to the angle of rotation ; this gives the specific rotation, by which is meant the rotation efiected by a solution of the substance containing one gram in one c.c. of liquid when contained in the one-decimetre tube. With any known strength of solution (which should be concen- trated) the specific rotation will be obtained by the following formula for yellow light : — _ a * -,, where 5=:specific rotation. a = rotatio n observed . »•= weight of the substance in grams contained in one c.c. of liquid. Z^the length of the tube. a To find the value of tv, the formula is thus modified : ?y= ,. In the case of diabetic urine, when we employ a tube one decimetre long, the degrees of the scale give approximately in grams the per- centage richness in sui^ar. With a two-decimetre tube first halve 74 NVTRITIO^' AND FOODS. the number of degiees. I\Ioie exactly the percentage is obtained by the formula .r= - , ,_, — , where x is the percentage sought, a the rotation with the one-decimetre tiiLe, and 56^ the speciGc rotatory power of gi'ape sugar. The solution, of sugar should be clear, or at least not present more than a slight yellow tint ; otherwise the excess of colour must be removed by filtration thrcngh animal charcoal. It should also be free from polarising bodies, like albumin, Arc. 2, With V entzTce- Soldi' s saccharhneter, aii'ange the instrument horizontally befoie the source of light, cutting off excess as before, and the movable Nicol is turned until the field assumes a pale rose or violet tint. This colour serves best for estimating the difference of colour in the two halves of the field of vision, and is therefore to be preferred. This done, the eye-piece of the small telescope is to be adjusted so as to enable us to see distinctly the line separating the two halves of the doiible plate. The rack of the compensator is next to be turned one way or other till we render the two halves of the field perfectly identical in tint. Ilej^eat this operation several times, and then note if at this point it corresponds to the zero of the scale. If not a correction must be made with the little button below the fixed Nicol, by means of which the latter is tui-ned a little to one side or other ; but tliis is rai-ely required, and should not be attempted by the ordinary student. At the zero of the scale, if the instrument is correct, the dextro-rotatory plates of the compensator are of such thickness and power as exactly to neutralise the levo-rotatory power of the plate of quartz. When working Avith an accurate instrument we may proceed at once to the estimation by making the zei'o of the vernier coincide with the zero of the upper scale, focussing, and colouring the field of vision of a rosy tint. Tlie instrument is well arranged if the two halves of the field continue of the same colour however the movable Nicol is turned. The clear saccharine solution or urine is then carefully poured into one of the tubes for the purpose so as to fill it co'iapletiljj, and it is inserted in its [dace in the polariscope. This tube should be kept very clean, before each determination being washed out with a little of the solution to be tested, and after the experiment with distilled water. Care should be taken to exclude air, and not to screw up tlie glass plates at the ends of the tube too tightly. On examination the coloration of tlie (loul)le jilate will no longer be seen to be uniform ; we therefoi-e turn the jack of the compensator to the riglit, so as to try to icproduce the two halves of the field with QUANTITATIVE DETERMINATION OF GRAPE SUGAR. 75 exactly the same tint. The movable Nicol may also be nioveil, if this has not already been clone, so as to secure a rose or other tint in which the observer can most sharply distinguish the least difference of colour in the two halves of the double plate ; nnd when Ave have obtained a uniform coloration, say of a rosy tint, the movable Nicol may be rotated to ascertain if the uniformity of the field persists with the change of colour. The observations, it may be remarked, should, for the sake of accuracy in the judgment of minute differences of colour by the eye, be made as rnpidly as possible, ten seconds at a time being fully sufficient. The scale of the compensator is then read, and the zero of the vernier will be seen to the right of the zero of the scale, indicatijig a dextro-rotatory body. The compensator is generally graduated, so that each degree of its scale represents 1 gram of sugar in 100 c.c. of fluid when the one-decimetre tube is used at a tempei-ature of about 17°; that is, each degree corresponds to a percentage. When the two- or half decimetre tube is emjiloyed, the number of degrees must be divided by the length of the tube. BiieHy, the steps may be thus stnted : The lamp is arranged so that the light traverses the axis of the instrument, the tube first being filled with pure water ; the ocular is then adjusted so that the field may be seen divided into two equal halves, of the same or dif- ferent tints separated by a sharply defined black line. If the two halves are of different tints, turn the horizontal screw-head one way or other till they are both alike. The tint most sensitive to the observer's eye may be chosen. The zero of the scale ought to coincide with the black line of the indicator; if not, it must be so adjusted. Fill the tube with the sugar solution and examine ; the uniformity of tint of the two halves of the field no longer exists. This is re-established by turning the horizontal button; and the original tint, which the solution has generally caused to disappear, must then be restored by turning the milled head. We therefore start with an equal or similar coloration of the two halves of the double quartz plate, and we finish with the same, the number of degrees through which the compensatoi- has had to be moved to re-estal)lish this giving the strength of the saccharine solu- tion. The observations are best made in a darkened room. JI. Fehling's Method by a Standard Copper Solution. — Tliis is founded on the property })Ossessed by grape sugar of reducing cupric oxide (CuO), when present in alkaline solutions, to the state of cuprous oxide (CujO), and depends on the fact that a definite mixture of cnpric sulphate, potassic tartrate, and caustic ?G NUTRITION AND FOODS. soda undergoes no change on boiling unless sugar is added. 80XIILET and others, however, have shown that the power of grape sugar to reduce this solution is not constant, but varies somewhat under different conditions. 1 eq. grape sugar (CgHj^Og^ 180) is capable of reducing the 5 eq. (397) of cupric oxide contained in 5 eq. of crystallised cupric sulphate (CUSO4 + 5H20 = 249-5 x 5 = 1247-5;. The most convenient strength is one of which 10 c.c. fully reduce O'Oo gram of grape sagar, and therefore contain 0-3464 gram cupric sulphate. Prejyaration of the Solutions. Standard C'oj^per Solution. — (rt) Roughly powder some pure crystallised cupric sulphate, and pi-ess it between some folds of dry filter paper; weigh 34'64 grams, and dissolve in moderately Avarm water, which is then to be diluted up to 500 c.c. with cold water. Preserve in a stoppered flask. (11) Dissolve 173 grams Rochelle salts in pure crystals in caustic soda (sp. gr. 1-34) 100 c.c, and dilute with water to 500 c.c. Preserve in a stoppered bottle. Air must be carefully excluded from both solutions, the tartaric acid, for example, in solution h tending to change into racemic acid, which reduces cupric salts. For use, mix equal volumes of the fluids a and h\ on shaking them together a dark blue fluid is obtained, of Avhich 10 c.c. = 005 gram sugar. A Mohrs burette and a jDipette capable of delivering 10 c.c. are required. If the Fehling's solution has been pre])ared for some time it is advisable to boil a little of it and then lay it aside for half an horn-, when, if it gives Jio precipitate, the solution will serve for the analysis. Process. — The solution to be tested should not contain much sugar; indeed, it must not much exceed 0'5 ^;e?- cent.; accordingly strong solutions, and most diabetic urines, should be diluted bcfoic being tested. Witli diabetic urine of high specific gravity dilute with 10 or 20 times its volume of water. Further, if the solution is of a very dark colour, or contains extractives that might interfere with the reaction, it is advisable first to boil and then add a little milk of lime, and when the precipitate has settled to filter through animal charcoal and dilute the washings to a definite volume. Place the dilute saccharine solution in llie Moln-'s burette, and having tran.sfcrred 10 c.c. of the Fehling's solution to a deep porcelain dish (or small flask), dilute it with 40 c.c. Avatcr. Place the dish over a lamp or Pun.scn burner, .and arrange the Inu'ctte a Utile altOAc it on QUANTITATIVK DETERMlXAriOX OF GRAVK SUGAR. 77 a stand. Hfiit tliMlilutcil l^'i'liling's solution, and wlien it is Ix'giniiing to boil allow the sugar solntion to ilow into it gradually; the red suIj- oxide is thrown down, and the blue colour of the solution gets less and leas. Boil again and repeat the addition of the sugar solution till the blue colour Juts disappeared, which is best observed by tilting the por- celain dish from time to time after the prefii)itatc has been allowed to subside (or, if a flask has been used, by holding it before a window), and Cixusing the fluid to rotate slo^vly round in the dish or flask. When this point has been reached, to ensure accuracy (especially with be- ginners) a few c.c. of the hot fluid should be filtered thi'ough a small thick Swedish filter, the filtrate acidulated with acetic acid, and a drop of potassic ferrocyanide added. If copper Ls present a brown colour or precipitate is formed. In this case more of the sugar solu- tion must be added to the diluted Fehling, and the operation com- pleted. It is always advisable to make a second experiment, and, guided by the indications of the first, to proceed more rapidly, as the precipi- tated suboxide tends to reoxidise quickly and redissolve ; and if com- paratively little of the diluted urine was required, the latter may be diluted with 20 instead of 10 times its volume of water; while, on the other hand, if but little sugar is present the dilution should be much less, or even no dilution made at all. Suppose 12"5 c.c. of the diluted urine reduced 10 c.c. Fehling's solution (=0'05 gram sugar), then the percentage of sugar= — '- 12-5 5 = =0'416 ; and, as the saccharine solution or urine has been 12 5 diluted ten times its volume, 0'41G x 10 = 4-16 per cent. ; or if it has been diluted 20 times, then 0'416 x 20 = 8"32 per cent. The results obtained, according to Wokji Muller, and IIagen, are -j''^ per cent, too high. The presence of alcohol, chloral, and bcnzoate of soda in the urine interferes with the accuracy of the process. Separation of Albumin. — With milk or albuuiiuous saccharine ui'ine acidulate 100 c.c. or so with acetic or hydrochloric acid, boil for some minutes, filter, wash the precipitate, and make up the filtrate to the original volume. Before Fehling's process can be applied to the determination of cane sugar, this body must first be converted into grape sugar by heating some 40 c.c. of its solution 20 minutes or so with 40 dro2)s of dilute hydrochloric or sulphuric acid (1 : 5), taking care not to char the sugar, and to replace the water that has evaporated ; then neutra- lise with carbonate of soda or lime, filter, and dilute with water. 78 NUTlilTION AND FOODS. To convert starch into grape sugar, to enable it to be thus estimated, 1 gram or so of it should bo made into a mucilage with 40 c.c. of cold water, and heated with 40 c.c. of one of the above dilate acids ; but the boiling requu-es to be continued 8 to 10 hours before the conver- sion into grape sugar is completed {^0^^^^^f)-^-\-'ii.,O=■(^^^'):l]^.J^^^ + 2CcH,,05 (dextrin). 95 parts of cane sugar or 90 parts of starch represent 100 parts of grape sugai-. III. Knapp's Method by Mercuric Cyanide depends on the reduction of an alkaline mercuric cjanide solution by the sugar, metallic mercury being deposited, and 100 parts anhydrous grape sugar being equivalent to 400 parts mercuric cyanide. Dissolve pure and dry mercuric cyanide 10 grams in water, add caustic soda (sp. gr. 1*14) 100 c.c, and make up to a litre. 40 c.c. coiTespond to 0"1 gram gi-ape sugar. The solution keeps well, and for this and other reasons its use is advocated by some authorities. Process. — Boil 40 c.c. in a beaker or small flask, and allow the urine or sugar solution, diluted to about 05 per cent., to flow in gradually from a Mohr's burette, as in the previous process, Avith con- tinued heating. The reduced mercury sinks slowly. To ascertain the end of the reaction remove a drop of the clear fluid from time to time with a. capillary tube, and place it on a ])iece of very fine filter paper ; expose this spot on the filter paper first to the vapour oF hydrochloric acid and then to that of sulphuietted hydrogen ; or it may be exposed to the vapour of ammonic sulphide for half a minute or so by bringing a diop down upon filter paper tied over a small beaker containing .some strong ammonic sul])hide. So long as exce.-s of unreduced mercuric salt is present the entire spojj becomes brown, and as less and less is present only the margin is coloured, and finally, when it is all reduced, the spot remains transparent. Only the coloration of iha fresh spot is to be taken as the indicator. It is advisable to dilute the mercuric solution, and to add tlie sugar solution in successive portions; rapidity is also necessary, as the deposited mercury redissolves (MCixek and Hacen), The i-esults are not more accurate than those obtained by Fehling's process, but the standard solution is easier to prejiare and keeps better. IV. Sachsse's Method. — Mercuric iodide ] 8 grams I'otassic „ . . . :5r> „ Cau.stic potash . 80 „ Water to 1,000 c.c. •JO c.c. = 0-15 gi am grape !-\igar. QUA:STITAriVE DETERMINATION OF GRAPE SUGAR. 70 Proceed as in Knapp's process. The end of the reaction is noted Ijy means of a solution of stannous chloride supersaturated with caustic soda. Some drops of this solution are placed ou a small porcelain dish and treated with drops of the mixture ; so long as the mercuric salt is present in excess a brown colour or a grey precipitate apjjears. V. The Fermentation Process. — This, as we have already seen, is applied to the peculiar decomposition that most of the carbohydrates of the composition CgHj^Og undergo, in dilute aqueous solutions, under the influence of beer yeast. It con- sists mainly in the resolution of the sugar into ethyl alcohol and carbonic anhydride, about 95 per cent, of the sugar appear- ing to undergo this change. The fermentation occurs most readily between 20° and 40°, best probably about 35°, ceasing at 0° and being retarded by reduction of pressure. CeH,20g = 2C.JIgO + 2CO2 ; that is, 1 molecule grape sugar (180 by weight) gives 2 molecules carbonic anhydride (88 by weight), or 100 002 = 204-54 sugar. The estimation may be made either from the loss in weight of the apparatus, owing to the evolu- tion of the gas, or to the gain in weight of an absorption tube containing caustic potash connected with the escape pipe. Two small flasks are connected together as in the diagram a 20 c.c. of the sugar solution or diabetic urine are poured, then some drops of a solution of tartaric acid, and a piece of well-washed yeast added, and h half filled with strong sulphuric acid. Now weigh the aj)paratus and lay it aside in a warm place (20° to 24°), and after 48 hours weigh again, having first heated a to about G0°, drawn air through, and allowed the whole to cool. The loss iu weight XvJ or 2045=the grape sugar. Experiment.— ^^.^^^^ Flask and saccharine urine . . 58oJ: Fla.sk 23-.32 Urine 35-22 The apparatus before fermentation. 13J:820 The apparatus after fermentation . 134033 Carbonic acid 0'787 Into FlC. 13. — Al'l'AIiATU.S KOU AscElt- TAIXING THE QUASJITY OF CAK- b:ixic Acid i-ro.m the Loss ix Weigut. Into a is introduce,! the saccli.arine solution, together with some ilrops of a tartaric acid solution, and then a piece of yeast ; b contains a little strong suliilioric aciil, into which tlie evolved carbonic acid passes through t from a, aud escapes by e. As 48-89 CO2 correspond to 100 sugar, therefore 0-787 = 1-609 sugar. 80 NUTRiriON AM) FOODY'S. Accoidingly the 35'22 grams of urine contain 1"G09 giam sugar, or 1,000 contain io'GS grams. The .same result can be obtained more readily by multiplying the loss in weight by 2-015, as 0"787 x 2 0-15 = 1-009 sugar. By connecting with the exit tube of b a weighed Licbig's bulb ap])aratus containing caustic potash (,sp. gr. 1-27) the dried carbonic anhydride escaping will be absorbed and give rise to an increase in weif^ht. As an additional precaution, that the escaping gas should be thoroughly dry before entering the potash bulbs, it may be passed thi-ou'^'h a drying tube filled with calcic chloride or pumice stone and sulphuric acid. Each gram or fraction of a gram of increased weight is equal to twice the same amount of sugar, or more correctly to the increase in weight X 2-045. VI. Estimation from Loss of Specific Gravity in Fermenta- tion. Differential Density MetJtod (Egberts). Process. — Take accurately the specific gravity of the fluid, and in doing so it is better, as Dr. Egberts advises, to use two urinomcteis with very long stems, one ranging from 995 to 1,025 and the other from 1,025 to 1,055. The temperature of the liquid should also be taken, and filtration performed if necessary. Place about 4 oz. (0 50 litre) of this fluid in a 12-oz. flask or bottle; add to it a lump of washed yeast the size of a small walnut ; then lay it aside, having stopped the mouth with a nicked cork so as to allow the gas to escape. After 24 hours in a warm place allow the scum to subside and take the specific gravity of the decanted liquid. It is often more convenient to ])lacc a tightly-corked 4-oz. bottle filled with the same solution or urine, but without any yeast, beside the specimen containing the yeast. After about 18 hours the two bottles can be removed to a cool place for 2 or 3 hours, and their densities then taken. In this way any error as to the effect of difference of temperature on the density can be avoided. The numljor of degrees of density lost indi- cates the number of grains of sugar per oz, ; and the percentage is obtained by multi])lying the degrees of density lost by 0-23. Thus in a urine Avhose density Ijefore fermentation was 1,053, and afterwards 1,004, the degrees of density lost=49, and accordingly 49 grains of sugar are present per oz., or 49 x 0-23= 11 -27 per cent. MaxasseTn gives 0-219 as the multiplier instead of 0*23, and con- siders that for practical purposes the method may be regarded as very nearly exact. Fieckoiiing, then, each degree of density lost as =0219 per cent, of sugar, end taking the density to be 1,029 before and QUANTITATIVE DETERMINATION OF GIUTE SUGAR. 81 1,0U5 after fermentation, the difference 24 x 0-219 = 5-2G grams=the percentage of sugar present. VII. VoGEL has also proposed a method for the approximative de- termination, depending? on the intensity of coloration produced by boiling tlie solution to ])0 tested with caustic potash. A standard of comparison is obtained by boiling a definite weight of pure and dry grape sugar with an excess of caustic potash. Dr. Garrod uses a strong solution of carbonate of potash instead of the caustic potixsh. And Dr. George Johnson has devised a quantitative method depend- ing on the depth of tint yielded when the saccharine solution is boiled with liquor potassai and a saturated sokition of picric acid, as compared with the tint of a standard of comparison (see under Diabetic Urine). CHAPTER XIV. IXOSIT. INOSIT, C^H,,0^+2H,0.— Tliis saccharine body is met with in the muscle substance of the heart, and in most of the organs of the body, as the brain, liver, spleen, lungs, kidneys, \k.Q. ; it has been separated from horse's flesh, the blood of the ox, and the fluid of hydatid tumours; traces of it exist also in most diabetic urines, and it has been noticed in a few cases of diabetes completely or partially to replace the grape sugar, and in about 17 per cent, to accompany the grape sugar; further, it has been found occurring in some 8 per cent, of the cases of Bright's disease, and it has been detected even in healthy urine (CLOiiTTA, KuLz), especially after aliundant ingestion of water or the use of diuretics. Preparation. 1. From the Juice or the Water u Extract of Mv,s('lc. — First coagulate the alljumiu by boiling the fluid after the addition of acetic acid ; then add Ijai-yta water to the filtrate to precipitate the l)hosphates ; filter, and throw down excess of baryta with dilute sul- phuric acid; concentrate the filtrate, which causes kreatin to crystal- lise out. Next treat the hot decanted liquid with four times its volume of boiling alcohol, and if an abundant precipitate is formed, but adhering to the sides of the vessel, decant ofi" the spirit ; while if the precipitate docs not settle leadily filter the hot liquid tluough a hot fannel, and leave the filtrate to cool. In 24 hours a crystalline deposit has formed ; decant and filter the supernatant liquor; then wash the collected crystals with a little cold alcohol, dissolve them in 82 NUTRiriON AND FOODS. a little boiliug water, and reprecipitale with alcohol. If no precipi- tate appears on the addition of the excess of boiling alcohol, ether is to be added until it appears, and after the mixture has been well stirred the whole laid aside to crystallise. Or, after separating the albumin, treat the filtrate with neutral lead acetate, and warm the filti'ate from this with basic lead acetate ; collect the precipitate after twelve hours and having washed it sus- pend it in water, and decompose with sulphuretted hydrogen. The concentrated filti-ate will yield iuosit on concentration, particulaily after the addition of alcohol. 2. From Urine containing it. — Use several litres of weakly acid urine, and proceed as with the juice of muscle, adding neutral and then basic acetate of lead. After the precipitate with the last has stood twenty-four hours, decompose it as before with hydvic sulphide, filter, and after standing some time decant the clear liquid from the pie- cipitated uric acid into a porcelain capsule, where it is to be evapo- rated to a syrup and then precipitated with absolute alcohol. The precipitate is to be dissolved in hot water, and three to four times the volume of the latter of alcohol (90 per cent.) added ; ether is next poured in until a turbidity is produced, and then the mixture is left for the inosit to crystallise out. 3. It is readily prepared from French heans. A watery extract is made, which is evapoi-ated down to a syrup and then precipitated with alcohol ; the precipitate is dissolved in water, and the inosit allowed to separate by crystallisation (Von i.). Properties. — Forms large, colourless, efflorescent, monoclinic tables, or fine clinorhombic prisms, generally grouped in rosettes. From its solution in boil- ing spirit it crystallises in brilliant little lamelhe somewhat like those of cholesterin. It has a sweet taste, and is easily soluble in water, 1^ ^'? "^ ^-^ ii^^ but insoluble in absolute alcohol ^I^B i and ether. F,.;. 14.-C.CVSTA,.. OK isosiT. ^^'l^en compared with other sugars many of its properties are negative, thus : it is not decomposed by caustic alkalies or by weak acids ; it has no ])olarising action on light, neither does it ferment nor I't'duce metallic oxides ; it gives no change of colour when boiled with caustic potash, and no reduction of copper with caustic potash and cupric sulphate. Although in- ixosir. 8« capable of alcoliolic- fermentation it undergoes lactose fermenta- tion when in contact with putrid cheese or decaying animal tissues and chalk, yielding fermentation or sarcolactic(HiLGER), butyric, and carbonic acids. It is precipitated from its solutions by l)asic lead acetate and ammonia. Tests. — 1. Evaporate a little of its solution containing a few drops of nitric acid nearly to dryness on a platinum disli ; treat the residue with a little ammonia and calcium chloride, and evaporate to dryness at a gentle heat : a bright rosy red or violet colour is produced (Scherer). The reaction is delicate, but it only succeeds with pure solutions. 2. Add a drop of silver nitrate to a solution of the inosit in a porcelain dish, and a yellow precipitate is formed. Spread this out carefully on the sides of the dish and heat gently, when it will become dark red or rose-coloui^ed ; on cooling the colour disappears. Albumin, tyrosin, and sugar must be absent (Gallois). CHAPTER XV. FATS. Constitution. — Fat is generally a mixture of the neutral fats stearin, palmitin, and olein, the two former of which, being solid at ordinary temperatures, are held in solution by the olein at the temperature of the body. These fats, as we have seen in a previous chapter, are derivatives of the triatomic alcohol glycerin, and may be regarded as organic salts of glyceryl, glycerides, or, as they are tenned, compound or glycerin ethers of palmitin, stearin, and olein, in which the hydrogen atoms of the glycerin are replaced by an equivalent of the acid radical. In the fat stored up in or about the internal organs as well as in the fat of marrow there is not so much olein as in the sub- cutaneous fat. In the infant body the fatty tissues are firm and hard, and the fat forms a homogeneous, white, solid mass, melting at 45° ; it contains more stearic and palmitic acids and less oleic acid than adidt fat. 84 NUTlllTIOy AND FOODS. Oleic acid Palmitic „ Stearic ,, Iirant Adult f.7 75 89-80 28 !t7 8-16 3 28 2-8i (Langer). Traces of free fatty acids have also been found in human fat by HoFMANN", and as to vegetable fats Konig and Eecke conclude, from their glycerol determinations, that they consist essentially of free fatty acids. Adipose tissue is made up of little rounded or polygonal cells filled with fat. These cells generally lie in groups, and are al- ways in close relationship with the blood vessels. The fat in the cell is not solid during life, and the radiated fine crystalline needles or thin plates occasionally present are most probably post mortem in their appearance. These crystals used to be described as margarin, but they are really a combination of stearin and pahnitin. The fat may also be found in a state of solution, fine subdivision, or admixture with other tissues or fluids throughout the body, PALMITIN, C;5Hr,(Ci,;H3i02)3, is more abundant than stearin in human fat, and is the chief component of most animal fats, although it also occurs largely in vegetable fats. It is more soluble than stearin in alcohol and ether, but it is only slightly soluble in cold alcohol. It ciystallises in fine needles, and three points of fusion are ascribed to it, 4G°, 61°, and 02-8° (Duffy). It is readily 2jre2Kired by digesting palm oil repeatedly with alcohol, dissolving up the residue in ether, and repeatedly crystallising therefrom. STEARIN, C..,n,,(C,glI;j.,0.^);j, is the hardest fat of the body, and also the least soluble or fusible. IL is nearly insoluble in cold ether, and, owing to this property, it is possible to obtain pure stearin from Buet, in which it is abaudant, by filtering the melted suet and exti'Hcting it repeatedly with cold ether before dissolving in hot other, from which it crystallises out, on cooling, in little mother-of- pearl-like leaflets. Allhough never found in vegetable fat it occurs in most animal fats to a greater or less extent. It crystallises from its boiling alcoholic solutions in brilliant quadi'angular ])lates. Stearin melts at GS*^ to GG°, according to Heintz there being two points of fu.sion, 55° and 71'G°; but the melting point varies considerably, being affected by tlie application of a high temperature ; and it is probable there are three isomeric modifications of it, each with its own melting ])oint, 52°, G3°, and GG°. FATS. 85 OLEIN, C;,H;,(C,,sH;,.j02);j, Is .'I Hiucl, coloiu'less oil tliat becomes yellowish when exposed to tlie air, and is the fluid constituent of most natural fats and fixed oils, dissolving palmitin and stearin in great quantity. It is moie abundant in vegetable than in animal fixts, and according to some authorities it exists in smaller proportion in human fat than is generally stated. It can easily be obtained from olive oil, from which the palmitin has already been in great part separated by cooling the oil down to 0°, then dissolving the liuid residue in alcohol and cooling once again to 0°, when the rest of the palmitin crystallises out ; now dilute the alcoholic filtrate with water, and the triolein will separate. General Properties. — The fatty bodies are in part liquid and in part crystalline at ordinary temperatures ; they areinsoluble in water and cold alcohol, but readily soluble in boiling alcohol, also in ether, chloroform, benzol, bisulphide of carbon, and the essential oils ; they are slightly soluble in solutions of soaps, albumins, and biliary acids. Dropped on paper they render it transparent, especially when heated. Tbey are readily decomposed by superheated steam under a high pressure, also by the action of boiling caustic alkalies, as soda or potash, being saponiJteJ, as it is termed, and with ammonia foi-ming ammonia soaps or liniments ; the oxides of the heavy metals likewise decompose them in a similar way, with the formation of jilasters. When strongly heated they disengage a characteristic peneti'ating odour, very irritating to the mucous membrane of the nose and eyes, and due to the formation of aci-olein, and at a red heat they evolve a mixture of gases, the chief of which are carbonic oxide, hydrogen, marsh gas, and olefiant gas. They decompose slowly in contact with the air and become rancid. In the process of digestion they are subjected to the processes of saponification and emulsioia. In the latter the fat is bioken up into fine drops, each of which is investevl with a thin albuminous coating, and thus maintained apart. The phosphate of soda present in bile is regarded by Thldichum as in- fluential in the production of the emulsion in digestion. Origin and Source of the Fats in the Organism. — Part of the fats is absorbed as such in the intestine, and enters the capilla- ries in the form of scarcely saponified glycerides, that are sub- sequently transformed into alkaline soaps. But they also arise in the body at the expense of the albuminoids. It seems doubtful whether any of the fat is derived directly from the sugar ab- sorbed, thougli this is asserted ; but it is probable that the accumulation of fats occurrinu' on a mixed diet rich in suffar is 86 NUriilTION AND FOODS. due not to the conversion of the sugar into fat, but rather to the protection thus aflforded against the oxidation of the fats. That, however, a large proportion of the fat of fattened animals is not derived fi-om ingested fat, but directly or indirectly from the carbohydrates as well as the nitrogenous elements of the food, particularly when the latter are in excess, seems most probable, and there is no doubt but that a combination of nitro- genous food and saline matter, together with carbohydrates, conduces most to the production of fat in the organism. From experiments upon geese B. Schulze concludes that, as the fat formed was some 20 per cent, in excess of what could be produced by the conversion of the nitrogenous matter of the food, the carbohydrates, under certain conditions, play a distinct part in the formation of fat in the carnivora and herbivora. When a proteid is broken up we know that one of its deri- vatives is urea, 100 grams of this body containing as much nitrogen as 300 grams of the proteid ; but in addition to this there is a large excess of carbon, &c., to be disposed of, and it is probable that this, or part of it, may go to the forma- tion of fat if not immediately required by the organism. Thus VoiT reckoned that 100 parts albumin furnish 33*45 parts urea and 40*08 parts fat, while Henneberg gives it as 51-39 per cent, fat, 33 4 per cent, urea, and 27*4 per cent, car- bonic anhydride. According to Kubxer, for every 43*3 grams fat 100 grams nitrogenous matter have been destroyed. The assigned sources are therefore : 1. The fat of the food absorbed as such, although this accounts for but a small pro- portion of the stored up fats, some authorities even being of opinion that all the fat taken in the food is directly disposed of. 2. Some is also derived from the carbohydrates, a partial conversion of which into fats occurs in the butyric acid fer- mentation in the intestine. 3. But the gi'eat source seems to be found in the jrroteids, although an exclusively proteid diet, from the increased activity of the organic processes, does not tend to cause an accumulation of fat, rather, indeed, the contrary ; but it has at least been satisfactorily proved that fat may l^e derived exclusively from this source. It should also be remembered that the constitution of the fat of the body does not appear to be modified l)y the nature of FATS. 87 the food ; for if an animal is starved, and tlien largely fed on pahnitin, olein, and lean meat, yet stearin will still make its a])peai-anee in the body fat (Suhbotin). Destination of the Digested Fats. — The fats tliat are not stored np, or taken np by the tissues requiring them, disappear probably by direct oxidation, being ultimately transformed into water and carbonic acid, and evolving much heat in the process. Distribution of Fat in the Body. — Fat is one of the most fluctuating constituents of the organism. In the normal con- dition it is pretty generally distributed throughout the body, and it frequently makes its appearance as a degeneration pro- duct of many of the tissues. Besides being enclosed in the cells of adipose tissue, over 83 per cent, of which consists of fat, it is also found free, being met with in this condition in the chyle, blood, lymph, milk, &c. Its proportions in some of the tissues is indicated in the followinof table : — Yellow maiTow of 1 tones Adipose tissue Brain (Fremy) Muscle (BiJjRA) . Chyle (Liebig) Healthy liver (BouDET) Bone .... Cartilage Blood (Lecaxu) . Lymph . • . . Per cent. 960 82-7 5-8-0 1-.5-4-24 2-2-18 1-77 1-i 1-.3 0-.5-0-16 0-26-0-05 Tests for the Presence of Fats or Fatty Acids. — 1. Wa.sh out a beaker or wine glass very carefully with caustic potash, and then with some boiling alcohol or with ether, and afterwards rinse it thoroughly with water ; now ])lace it in a shallow saucer, and fill the beaker or wine gla.ss to overflowing with distilled water. A small bit of camphor, detached from the middle of a freshly broken lump with the point of a knife, which has baan washed in ether, is next l)laced on the surface of the water, when it will be seen to rotate and move rapidly about — a movement, however, that will immediately cease when the slightest trace of oil or fat is brought in contact with it or with the surface of the water. 2. The presence of a free fatty acid is shown by warming the solution containing it with a little rosanilin hydrochloride solution, when a dark red to a reddish l)lack colour makes its apj^earance. 88 NUTRITION AND FOODS. Detection of Fat in a Mixture. — When only a small amount of f;\t LS present in a mixture it is best to evapox-ate it nearly to dryness on a water bath, and to digest the residue with a little warm ether. The ethereal solution is evaporated, when the fat will be deposited, and if this is done on a glass slide very minute traces may be dis- covered under the microscope, and the particles may be seen to be immiscible with water, and to break up into minute globules when rubbed with a drop of hot water, also to dissolve in warm caustic potash, and to produce acrolein at a high temperature. Jn the case of solids dry them thoroughly, reduce them to powder if possible, and then exhaust with ether as above ; filter the ethereal extract into a flask, and having added to the filtrate some caustic soda shake well. Any free fatty acids are converted into salts of sod:v, which dissolve in water, while the neutral fat remains dissolved in the supernatant ether. Decant the latter -vvith a pipette and w\arm the wateiy solution on a water bath ; then supersaturate with hydro- chloric acid, which precipitates the fatty acids. Dissolve up the precipitate in alcohol, and treat the solution with an alcoholic solution of neutral acetate of lead. The precipitate digested with boiling ether gives up oleate of lead, while the palmitate and stearate remain undissolved; but the residue, when decomposed with hydrocliloric acid and treated with boiling alcohol, yields free palmitic and stearic acids. Determination and Separation of Fat.— The tissue, finely divided, is exhausted with boiling ether, and the ethereal solution is evaporated to dryness in a tared capsule, whose incrciise in weight gives the total fat. Dreschel's apparatus is very convenient for this pur- pose. The upper flask, which is fitted to the lower one, is in con • nection with a Liebig's condenser, and contains on a fluted filter tlie finely divided solid from which the fat is to be extracted. In the lower flask is the ether, whose vapours are condensed in the Liebig's apparatus, and in their way back pass through the upper flask. A constant circulation is thus niiiintained, and the dissolved fats gradu- ally accumulate in the lower flask. 89 CHAPTER XVI. PROTEIDS Oil ALBUMINOIDS. It has been proposed to define proteids to be nitrogenised colloids, which by hydration split up into amidated acids, car- bonic acid, and ammonia (GtRIMAUx). These bodies, which chiefly include the albumins, are the most essential to any dietary. When assimilated they are gradually decomposed into simpler compounds, that are burnt up in the economy, passing through a series of transformations, of which the final products are water, carbonic anhydride, and urea. Where found. — These bodies form the important solid con- stituents of the blood, nerve, muscle, glands, and organs gene- rally of the body ; they also constitute more than half the solids of the grey matter of the nerve centres, and about a fourth of the solids of the white matter of the same : they form, in fact, in combination with much water, and associated with certain acids, bases, and salts, the chief mass of the animal tissues. In all protoplasms tliere appears to exist a vitellin- as w"ell as a myosin-like body (Eovida). In the normal state such fluids as urine, bile, and tears should be devoid of them. The albumins seem to exist in a special state of hydration, apt to be modified very rapidly and unceasingly under the in- fluence of variations in the salts dissolved in the different fluids of the economy (CtAUTIEk). General Characters. — These albuminous bodies are white, flaky, or granular, and mostly amorphous, and accordingly diffi- cult to obtain pure ; they are colloidal — that is, they are not diffusible through parchment paper, and their aqueous solutions polarise to the left, the amount, except in the case of peptones, being altered by heat. Proteid crystals have been met with in white of agg.^ semen, and in seeds of plants, &c., and it is also possible under certain circumstances to cause proteids to crys- tallise (Dreschel). Some of these albuminoids are soluble and others insoluble in water; they are soluble also in mineral acids and the causi ic alkalies, but are almost insoluble in alcohol and 90 NUTHITIOX AND FOODS. ether. They can all become insoluble, either spontaneonsly, as fibrin and myosin, or after the action of heat, as egg and serum- albumin, or under tlie influence of weak acids, as casein. They also all yield an apparently identical substance, syntonln, which is soluble in water containing acid or alkali, but insoluble in neutral liquids ; and under the influence of gastric juice they are capable of generating peptones — bodies that are readily assimilable and highly nutritious. When heated they do not volatilise, but when burnt they give off empyreumatic products having the odour of burnt horn ; they likewise putrefy rapidly when exposed to the air. Their solutions polarise to the left, the amount being altered by heat. Composition, Constitution, and Formulae of Different Albu- mins. — Analyses of albumins indicate such a percentage com- position as the following (Wurtz): — C 52-7 to 54-5 H 69 „ 7-;5 N 15-i „ 17-0 O '20-i) „ 23-5 S 0-8 „ 2-2 Crystalline albumin from hemp seed and ricinus seed gave the accompanying nearly identical numbers (Ritthausen) : — Hemp Eicinus 'er cent. Per cent. 50-98 50-88 r)-92 G-9S 1873 18-58 22-»5 22-71) 0-82 0-77 Albumins also contain normally a small proportion of lime, that can only be obtained by incineration and is not removable by acids. According to Schltzenbekger, albumin is a complex ureide — a derivative of urea and oxamid, and containing ^tli its nitrogen in the form of urea — and pcssibly it may be regarded as a complex combina- tion containing amidatcd acids united to an acid a:; (CjH^NO.,) minus tlio elements of water. It decomposes into ammonia, carbonic anliy- diido, oxalic and acetic acids, and a nitrogenous residue from wliich the amidated acids, Arc, are derived. TjIEHH! and (Jekuardt con- sidered alljunniioid bodies to be isoineiic — tint is^ of the same com- PROTEIDS OR ALBUMINOIDS. 91 position, but (lifTeiiiig intlieir molecular anangements — while EiscH- WALD regarded them as formed of one and the same substance, modi- fied by combining with colloids and ciystalloids. As to foriividiv, they are untrustwoi-thy and purely empirical. LiebekkCiin assigns albumin the formula C^oHuoNiyOgoH, to its monatomic metallic combinations 072^,1 iR'NigSO^^, 'ind its dia- tomic C,,,,H222R"^36^i^44» ^ indicating the metal. LoEW gives it as CyoHiosNij^O-.oS, while Sciiutzenberger raises the numbers to c^24oh;,o.No.o;,s; The percentage composition of some of these proteids is given in the sulyoined list : — C H N s Authoriti' Albuiuiu (of egg) 52-9 7-2 15-6 23-9 0-4 WuETZ and Mulder Gluten 53-5 7-5 U-6 24-4 — PaTTHAUSEN Sj'ntonin (of muscle) 54-06 7-28 1605 21-5 1-11 LlEBIG Casein (of milk) 53'5 7-1 15-8 22-7 0-9 Dumas, Verdeil Fibrin (of blood) 52-7 7-0 16-6 22-2 1-5 Dumas, Rtjlling Vitellin (of yolk) . 52-3 7-3 15-1 241 1-2 GOBLEY Haemoglobin 53-85 7-3 16-17 22-3 0-39 Fe = 0-43,HOPPESEY- LER Combinations. — Albumin forms a series of definite combin- ations with acids, as Cy^HngNjgO.aS-f 2HC1 and C^aHuzNisO.jS + H^SO^. LoEW describes a series of combinations with nitric acid, &c., of which the trinitro-albumin is an example : C;,H,„,(NO,),N„SO,,. It also combines with bases, as O.^HnoNigSO^^H-KgO ; but it must be confessed that the true constitution and molecular weight of such bodies are as yet only imperfectly known. Derivatives. — Almost all proteids furnish certain derivative amides, named leitcin and tyi'osin. When 100 parts of a dry proteid are boiled for several hours with an excess of sulphuric acid diluted with one and a half time its weight of water, leucin and tyrosin will be furnished in the following propor- tions : — Albumin of egg Syntonin of muscle Fibrin of blood Horn ..... Elastic tissue .... Other important deri\atives are glycocin (CgH-NO.^j), aspar- tic acid (C^HjNOJjand glutamic acid (CgH^NOj. All proteids, Leucin Tyrosin 10 1 18 1 14 0-8 10 3-6 3G-45 0-25 02 NUTRITION AND FOODS. wheu boiled with dilute sulphuric or hydrochloric acid and a little stannous chloride, are exactly resolved into aspartic and glutamic acids, leucin, tyrosin, and ammonia, and may there- fore be regarded as formed by the combination of these bodies with elimination of water (Hlasiwetz and Habermann). As the result of their final oxidation in the body albumins yield water, carbonic anhydride (CO^), and urea (G^\-i_r'0. What the intermediate products may be we do not yet know, though we are familiar with some of them, such as leucin and tyrosin, as well as such carbohydrates as glycogen (CgH,QOr,), and fats. The term metabolism, it may be said, is applied to such a series of chemical transformations as a body like albumin undergoes in its passage through the organism. When heated with water and bromine under pressure, albu- min furnishes bromanilin (1"5 per cent.) and tribromacetic acid (22 per cent.), both secondary tyrosin products ; also bromo- form (30 per cent.), oxalic acid (12 per cent.), aspartic acid (23"8 per cent.), and leucin (22*6 per cent.), &c. &c. On exposure to the air these albuminoids ]iutrefy readily, fine granulations developing in their interior, which change into vibrios, oxygen at the same time being absorbed, carbonic anhy- dride, nitrogen, hydrogen, sulphm'etted hydrogen, ammonia, &c., being disengaged, and a series of simple bodies, such as leucin, fatty acids, and tyrosin, being formed. As Pasteur has shown, these little organisms, which are the excitants of all fermentative and putrefactive processes, are derived from the aii', and require a certain supply of oxygen for their development : accordingly, if they are excluded, destroyed, or deprived of the supply of oxygen necessary for the manifestation of their properties, then even such an unstable body as alliumin may be long preserved unchanged. The most important fermentation of albuminoid matter is occasioned by hacterium termo, and it is this bacte- rium that induces the decay of all organic matter (Marp- mann). Stated generally, we may thus sum up some of the iilliuinin derivatives ; albuminates, by the action of ;icids and alkalies ; ('(hkjv,- latrd allmmin, by boilin,y (he prolonged action of alcoliol ; pcplon, hy the action of pepsin in pvcsonco of a dilute acid^ riiOTEIDS OR ALBUMINOIDS. 93 which, when trypsin and a dihite alkali are used instead of" the acid pepsin, partly splits up into leucin and tyrosin. When a mixture of albuniin and pancreas is allowed to decompose, indol, skatol, phenol^ biUi/ric and vfdcrumlc acids, leucin and tijrosin appear. Early in the decomj)osition, before indol shows itself, ItijpoxanOun is formed. Most of the immediate decomposition products of allnimin, then, are amides, or bodies that may be regarded as derivatives of one or mox-e molecules of an ammouiacal salt : thus we have glycocin and leucin ; amides with ai'omatic radicals, as tyrosin ; and sulphamides, like cystin ; as well as acids and aldehydes corresponding to the pre- ceding amides. Sometimes the derivative contains sulphur in place of one of the other elements. In taiirin or isetldonaiaide the sulphur ( r* TT OTT is combined with oxygen, SO2 -NrrVr ^" ; while in cystin it replaces the oxygen and saturates the carbon, (C3H3S)'" -OH . Certain proteid derivatives, such as protagon and lecithin, contain phosphorus, this element playing the same part as in phosphoric acid I H3PO4— PO 1 OH 1. Glycero-phosphoric acid, for example, one of the decomposition products of protagon and lecithin, may be thus OH expressed : PO OH 0[C3H,(0H),]. _ a. Aitionj th^se dccoiajwsUioih ]))'odt'Cts at least three aronialic groups are 2>resent : — 1. The phenol y7'oup — tyrosin, the aromatic oxyacids, phenol, and kresol. The tyrosin does not appear as such in normal urine, but its decomposition products present themselves. 2. The phenyl yronp, as phenylacetic and [ihenylproijionic acids. The latt.-r is oxidised to the state of Ijenzoic acid, and appears in the urine as hippuric acid (Salkowski). 3. The indul (/roup, as indol and skatol. In an oxidised form, and combined with sulphuric acid, these two bodies appear as indican and skatoxylsul[)hate. fS. As ivell as a yroiq) belomjiuy to the fatty series, and including such bodies as leucin, aspartic acid, and hypoxanthin. Origin, Destination, and Theories as to the Terminal Products of the Decomposition of Albumin. — Under the influence of the Solar rays plants (Iccompose the carbonic anhydride in the atmosphere, evolving the resulting oxygen and fixing the car- 04 NUTRITION AND FOODS. bon. A series of otliev reactions also occur in the plant in which higher and more complicated bodies are formed at the expense of simpler bodies, such as water, ammonia, and the like. While we may theorise as to the general nature and direction of these reactions we are as yet ignorant as to their exact cha- racter or their order of succession. But, as their result, in the laboratory of the plant from simple bodies sf)ring bodies of more complex constitution, until we arrive at the albumins, in which is stored up the great amoimt of energy expended in their elabo- ration. These vegetable albumins are subjected to certain changes in the stomachs of the animals feeding upon them, by which somewhat simpler bodies, capable of dialysis, are formed. To these so-called fejptones TB.mY gives the composition C= 15-34, H=7-25, N = 16-18, S = 2-12, O and P = 23-ll, which would seem to indicate that a substance of the nature of leucin had been separated. When absorbed as peptones or all)umiiiates, and thus introduced into the blood, pro baldly some combination occurs between these bodies and the alkalies and salts of the plasma, and in this condition possibly the tissues requiring albumin are nourished. Some of the absoi-bed substance unites with new elements to form haemoglobin, but the greater part undergoes retrograde metamoi'phosis, passing from a complex condition to a series of simple combinations, and evolving its energy in doing so. Fats, glycogen, mucin, and the coUagens gene- rally probably result from some of these alterations. Early deriva- tives are possibly asparagin and krcatin, bodies that are closely allied : Asparagin ..... C'^H^N.^O, Kreatin CiIT^NjO^. Guanidin also has been obtained as an oxidation product (Lossen). The different changes are gradual and progressive. This is well seen in the bodies sarkin, xanthin, and uric acid, wliich afford a marked example of this successive oxidation : Sarkin CJT.N^O Xanthin 0,11 .N.Oa Uric acid . . . . . C,H,N,,03. The sarkin, -wliich is one of the liigher albuminoid derivatives, in being oxidised gives rise in succession to xanthin and uric acid; and we may trace the decomposition still further, as shown in these reactions : — mOTEinS OR ALBUMINOIDS. 95 (Uric acid) (Allaiitoiii) C.HbN^Oj + 2U,0 + = C,lI,,Oj + 2C0X,1I , (Alliiiitoiii) (Oxalic aciil) (Urea) C„HA+0 =2C0,,+ 1L0 (Oxalic acid) From saikiu we thus come by gradual stages to its final decom- position products, urea, carl)onic acid, and water. Krcatin, xanthin, liypoxanthin, and the biliary acids are all gene- i-ally regarded as decomposition products of the albumins ; but as to the kreatin, which is so generally distributed through the organism, being a direct predecessor of urea, there is still some doubt. According to Schultzen and Nencki, albumin is decomposed into certain Ijodies belonging to the amido-acid series which pass into urea, wliile the non-nitrogenous part of the albumin may pass into the fatty series. They were further of opinion, in which they are supported by Hoppe Seyler and Salkoavski, that in the passage from albumin to urea cyanamid is probably formed. Under the influence of strong acids and alkalies albumin gives rise to leucin (amido- caproic acid, 0,;H,;jN0.2), aspartic acid (amido-succinic acid, C4H7NO4 or C,H3(NH2)(CO.OH).), tyrosin, CoHnNOg, and glycocin (amido- acetic acid, C_,H-,NO,). Somewhat similar substances ai'e obtained by the prolonged action of trypsin on albumin or gelatin. Schmiedeberg is of opinion that the nitrogen of the albumin passes out as ammonic carbonate, and that this, by the removal of water, forms urea. Danilewsky has obtained a crystalline compound having the composition CoiHo^NoOg on subjecting peptone, &^§^ albu- min, etc., to the continued action of pancreas ferment. In its chemi- cal reactions it partakes of the properties of both tyrosin and inosit, but it has a less stiibility than either of these bodies. Dkeschel supports the view that the amido-acids pass over into carbamic acid, two molecules of which form urea ; 2C0{JJfJ' =C0 (^.JJ' + CO,+ H,0. Traces of this carbamic acid he discovered in the blood. Salts of carbamic acid, he also finds, are formed by the oxidation of glycocin j and he considers it probable that ammonic carbonate is the immediate source of urea by the removal of the elements of water. In dogs, for example, it has been shown that ammonic carbonate and acetate are converted into urea (Hallervorden and Yoit). In the formation of urea from all)uminoids Drescheu concludes that these bodies are first resolved into glycocin, tyrosin, leucin, etc., and that these in tux-n 96 NUTRITION AXU FOODS. are oxidised into carbamates, that are finally converted into urea under the influence, possibly, of some ferment. According to Cazeneuve, the proportions existing among the amounts of uric acid, urea, and ammonia, excreted by birds, are not influenced by an increase or decrease of oxidation, but he finds that the total amount excreted varies with the quantity of nourishment taken ; from which it might be concluded that the albuminoid matters in the system undergo a decomposition depending on hydration rather than on oxidation. CHAPTER XVII. TBE PROTEIN BE ACTIONS AND ALBUMIN TESTS. THE PROTEIN REACTIONS.— Protein was a hypothetical • radical supposed by Mulder to exist in all albuminoid principles ; and as the three following tests apply to all such bodies, they received their designation accordingly. 1. A blue or violet coloration is obtained by adding to the albuminoid in solution a few drops of sulphate of copper solu- tion, and then an excess of caustic soda. The violet colour deepens on boiling, but no other change is produced. The same result is had by the addition of a few drops of Fehling's solution. In the case of a solid albuminoid, touch it succes- sively with the sulphate of copper and the caustic soda, and then wash the touched surface, when it will be found to be stained of a violet colour. The coloration can also be well sliown by shaking, say, a piece of fibrin, in some very dilute soluticm of cupric sulphate, when the latter will become colour- less, the hbrin taking a greenish tint, which, however, becomes violet when the fibrin is shaken up with some caustic alkali like lime, or baryta water, or caustic potash. 2. The xanthoproteic reaction, or yelloiu coloration, got by the action of strong boiling nitric acid, which is changed to an orange or amber-red colour by the addition of ammonia to the li) Acetic acid andferrocyaiiide of potassium give a white flaky precipitate, which is somewhat soluble in excess. (c) Acetic, tartaric, and citric acids, in [ircsence of excess of a cold saturated solution of a neutral salt like sodium chloride or sulphate, or of a body like guni or dextrin, precipi- tate albumin. The albumins, with the exception of casein and syntonin, are not precipitated by acetic acid alone. 4. Salts of the heavy metals, such as silver, mercury, lead, andcopjper, throw down albumin from its solutions. Basic lead acetate precipitates it abundantly, the normal acetate only slightly. Tungstate of soda and potassio-mercuric iodide are also very delicate precipitants. 5. Other precipitants axe freshly prepjared ferric acetate, carbonate of potash to saturation, alcohol, and aceton. A solution of taurocholic acid also precipitates albumin and syntonin, but not peptone or pi'opjeptone ; all the other delicate reagents for albumin also precipitate the peptones. 6. Colour Reactions. — (a) All the albuminoids, when dissolved in (jhicial acetic acid, give, on the addition of strow/ sidpliuric acid, violet blue, slightly fluoresces it solutions, and when sufficiently concentrated produce an absorption spectrum between h and f like urobilin and choletelin (Adam- KiEWicz). The presence of sodic chloride strengthens the reaction, but that of iodine spoils it. With peptones the coloration is well marked. {t)) Alljumiuuus fiulutiuus show a grccoi Uuoresccnce with reflected U 2 lOU NUTlilTIOX AND FOODS. light, whicli disajipears on the addition of acetic acid in excess. If tlie albumin is precipitated with silver nitrate, and the pi'ecipitate dissolved in a mixture of equal pai'ts of acetic and sidplncric acids, the colour of the solution i-apidly passes from violet through red and orange to yellow ; hut the addition of fresh sulphuric acid causes the violet colour to be restored in the inverse order. (c) When albumin is dissolved in stroig sulphuric acid alone a solution, differing in colour according to the quantity of reagent em- ployed and to the amount of albumin present, will be obtained : tlius 1 c.c. pure sxilphuric acid (sp. gr. 1-809) gives with 1'5 per cent, albumin a gi-eenisb yellow, with 7 per cent, an orange, with 15 per cent, a red, and with 22 per cent, a violet solution. (d) "When a little albumin is floated on or dissolved in water, a little sugar solution poured in, and then some concentrated sulphuric acid added carefully and with constant shaking, a pui-ple violet or beautiful red coloration is produced (Sciiultze). (e) When acted on with a mixtu7-e of sulphuric and 'inolyhdic acids an intense blue is developed (Froiide). (/) Concenti'ated hydrochloric acid dissolves it at a gentle heat, a blue, violet, and lastly a brown coloration being produced, and a ])recii)itate falling on neutralisation. By warming the albumin with hydrochloric acid to which a few drops of strong sulphuric acid have been added a violet liquid results. ((/) Iodine strikes a brownish yellow, and 'nitric acid a yellow coloration ; the latter is changed to a reddish orange by the addition of caustic soda. (Ji) Mix the albuminous body with a little dilute solution of cupric sulphate, add some caustic potash or soda, and warm ; a beau- tiful violet colour is produced. These colour reactions can be characteristically obtainc'd with mere traces of alVjumin on slides when examined microscopically. {j) Precipitate albumin with cldoride of gold, and dissolve the precipitate in a mixture of equal parts of acetic and sulphuric acids ; the i-ed solution, like the solutions of metallic precipitates of albumin, shows a broad band between E and v ; and a similar barul is given, as we have seen, witli the solution of albumin in acetic and sulphuric acids. Alteration of Albumin by the Action of Acids and Alkalies. — Til'' alhmiiiiis arf (•onv. 11 f)) with water, and test some of the solution with a current of cai'bonic an- hydride, when a precipitate will fall; to another portion add powdered magnesic sulphate to saturation, and a precipitate is formed ; and add alcohol to a third, wdien no precijntate will a[)pear. 4. To some of the alkali all)uminate solution add a little sodic or potassic phosphate, next a few drops of litmus solution, and then neutralise with dilute acetic acid : no pi'ecipitate itnll occur until an excess of acid is jivesent, as indicated by the red coloration of the litmus. But a precipitate may also be obtained by boiling the neu- tralised solution, owing to the conversion of the acid phosphate pro- duced in the reaction into neutral phosphate, fi'ee acid lieing thus liberated. {li) Acid AUniminatp. — 1. Place a little solution of albumin in a beaker, add to it an erpial volume of dilute hydrochloric acid (O-f) ]ter cent.), and lay aside for some hours, when the albumin will be converted into acid albuminate ; but the convei\sion is much accelerated by the application of a very gentle heat. 2. Boil a little of the solution thus obtained : no precipitate occurs. A dilute solution of albumin, slightly acidified, if very gradually brought up to boiling point, may in like manner give no precipitate. 3. Neutralise a little of the albuminate solution of 1 with dilute caustic potash solution : a precipitate is thrown down, llie j-iresence of an alkaline 2>Jiospliate does not interfere witli the precipitation. 4. Dissolve a little syntonin in lime water; boil half the solution, and a coagulum will be obtained ; but the addition of powdered sul- phate of magnesia to saturation to the other half causes no precipitate to appear, although it shows itself on boiling. The presence of nitrogen and sulphur in albumin may readily be shown by placing a bit of dried albumin or fibrin in a reduc- tion tube, and inserting in its mouth a piece of red litmus and 102 KUTBITIOX AXD FOODS. n hit of paper prepared with plumbic acetate ; tlien heat the tube, and after a little it will be seen that the litmus becomes blue and tlie lead paper black. Detection of Albumin in an Animal Fluid. — 1. Test the re- action. If too acid add a little dilute caustic soda without rendering it alkaline, then add sodic sulphate and ammonic chloride or a neutral salt of the alkalies, and boil. If alkaline neutralise with a few drops of acetic acid, carefully avoiding an excess, and boil as before. Precipitates will thus be obtained. 2. Test some of the solution with a little dilute nitric acid. 3. Confirm by testing with tannic acid and mercuric chloride ; or with picric acid, tungstate of soda, or potassio- mercuric iodide. Separation of Albumin from its Solutions. — 1. Acidify with acetic acid the fluid containing the albumin, and add an equal volume of a concentrated solution of sodic sulphate ; then boil. In this way albu- min can be separated from sugar and the like without interfering with the after-detection of these bodies. 2. The separation may be eflfected by boiling Avith acetic acid alone, avoiding excess, and any albumin still i^emaining in the filtrate may be complet'^ly removed by again boiling it after the addition of a little freshly prepared acetate of iron, obtained by satiu'ating acetic acid with ferric hydrate. Hydrated oxide of lead at boiling point also sepai-ates it completely. 3. Acidify strongly with acetic acid, and add twice the volume of alcohol ; filter in 24 hours. This is a good plan when other sub- stances are present which might be decomposed by»boiling. 4. Acidify with acetic acid, evaporate to dryness, and treat the dry pulverised mass with boiling alcohol, ether, and water. The albumins pre.S6nt are thus rendered insoluble. 5. Place the solution in a dialyser immer.-^ed in water : crystalloid constituents, such as the soluble salts, sugar, and urea, will pass through the parchment paper, and leave the albumin bcliind. It is ]Kjssible in this way to separate serum or egg albumin from parn- globulin, a.s the latter is precipitated wlien the salts keeping it in solution dialvse out. 108 CHAPTER XVIII. CLASSIFICATIOX OF ALBUMINS. I 8IIALL adopt more or less closely Hoppe Seyler's old arrange- ment, and give at, the same time some details as to each variety. T. NATIVE ALBUMINS.— These are soluble iu water, and precipitated therefrom by boiling, or by alcohol in presence of alkaline salts, though not in their absence ; but not precipi- tated by very dilute acids, alkaline carbonates, or sodic chlo- ride. (a) Albumin of Serum (Serine). — This is very widely spread in the jiuimal body, constituting a constant and essential element in all the nutritive fluids of the economy, such as the blood (2*7 to 4-22 per cent, of the serum, P'redekicq), lymph, chyle, milk, serous fluids, muscle juice, &c. ; it is also the most frequent form found in the urine in renal affections. Properties. -Diy serum albumin is yellowish and trans- lucent ; its solution, when containing only a small proportion of salts, has a specific rotation of —56° for yellow light (given also as — o7'27°). It is not coagulated by ether; nitric and hydrochloric acids precipitate it, the precipitate with the latter being soluble in excess, but reprecipitated on the addition of water. The temperature of coagulation, as we have already seen, is affected by the presence of certain acids and salts ; thus in the case of albuminous urine the coagulum may appear below 70°, and even as low as 50° when the urine has an acid reaction, but witli an alkaline urine coagulation does not com- mence till a temperature of 73° is reached. Dilute acids at ordinary temperatures give no precipitate, but at higher temperatures and with more concentrated solutions the precipitation is evident. Preparation. — To blood seiuni or hydrocele fluid add acetic acid drop by drop till a flocculent precipitate is formed ; then filter, and having neutralised the filtrate with a little sodic carbonate evaporate to a small volume in a shallow dish at about 40°. Dialyse the concen- trated fluid, clianging the outside water frequently, and after three 104 yUTJilTIOX AND FOODS. or four days evaporate the contents of the dialyser to dryne.^s. Some ash is still present. Or saturate the serum Avith crystallised mag- nesic sulphate, filter from the precipitated serum globulin, and dialyse the filtrate till no more chlorides or sulphates can be detected in the dialysate. Then evaporate the contents of the dialyser in vacuo over sulphuric acid. ( /9) Albumin of White of Eg-g:. — It is coagulated when shaken with ether in presence of alkaline salts. Hydrochloric acid precipitates it readily, and when added in excess it gives a coagulum that is with difficulty soluble in the concentrated acid ; serum albumin is not only more readily precipitated by but also more easily soluble in hydrochloric acid. If egg albumin is injected hypoderniically or into the veins, or introduced in large quantity into the stomach or intestine of an animal in a fasting condition, it is excreted unchanged by the kidneys, which is not the case with serum albumin (Stokvis). Pure albumin of egg, in which it is probable several albumins may be present, begins to coagulate at 54° to 59°, the coagulation increasing at 63° and 74°, but when mixed with salts the tem- perature at which this occurs varies considerably. According to Mathieu an.d Urbain, when all the free gas contained in albumin of egg is removed by exhaustion, a liquid albumin is obtained not coagulable by heat. After its precipitation by the mineral acids or the prolonged action of alcohol, the albumin is coagulated and rendered no longer soluble in water ; but the precipitate obtained by mercuric chloride, silver nitrate, or lead acetate is not coagulated, and is soluble on the removal of the precipitant. Egg albumin is most energetically })recipi(atGd by hent, serum albumin by alcohol. The opportunity may be here taken of giving tlie chemical composition of a hen's egg (after Poleck, Pahkp:s, Phout, S:c.) A hen's egg varies in weight between 4.5 and GO grams. Three parts of it are to he distinguished — the shell, the white, and the yolk. Therelations among these in weight may be expressed as 1 : 5 : 2-5, but when dried at 100° as 1 : 0-8 : 1-2. The proportion of the yolk to the white varies as I to 14, I'G, or 2*09, the white attaining its greatest weight in spring and tjic yolk in suinnior. (j) Tiie Nhell : — CLASSIFICATION OF ALBUMINS. 105 Oiganic substances 4-1 "> Carbonate of lime ..... It3'70 ,, of niao^nesia .... 1 'M Phospliate of lime and magnesia . . OK't (ij) Tlie rohite:— Solids 12-18 percent. Water 88-82 The .solids generally vary about 13'3 per cent., of which some 12"27 per cent, consists of albumins, with 0*5 per cent, of grape sugar, and traces of olein, palmitin, sodic oleate and palmiiate, and inorganic salts. These salts in 100 parts of ash have this composition : — K,0 . Na,,0 C'l . CO., . r.,0, ... (iij) The yo/Z; contains 44 to 55 percent, of solids ; these are vitcl- lin, nucleiu (0'2 to 0"3 gram in an egg), alkali albuminate, lecithin, ]>almitin, oloin, grape sugar, two })igments (lutein), and inorganic salts, especially potassic phosphate. 28-45 SO3 . . 2-63 27-90 CaO . . 1-74 2.')-20 MgO . 1-00 11-fiO Fe.,03 . 0-44 4-8:5 Si 6., '. . 0-49 Water Solids Albumins . Ether extractives : Lecithin Fats . Cholcsterin Alcoholic extractives (Lecithin Nuclcin Salts : Soluble Lisolnble . 47-19 52-81 14-15-02 r.-80 22-8?, 1-75 4-8.3 3 92) 1-50 0.35 0-61 The salts liave the following percentage composition Phosphoric acid Lime Potash . Soda . • . Magnesia Oxide of iron . Silica G:5-8-GC-7 12-2-1:5-2 8-0-8-9 5-1-G-5 20-2-1 1-1-1-4 0-.5-1-4 ir. THE GLOBULINS.— Insoluble in water, all dissolved by dilute sodium c-liloiidf solution (1 per cent.), but with the ex- 100 NUTBITIOX AND FOODS. ception of vitellin are precij)itated therefrom by saturated solu- tions of tlie same, or by the addition of a large quantity of water; soluble also in very dilute hydrochloric acid with the production of syntonin. Its solutions are coagulated by heat (not completely till 93° is reached), and are precipitated by alcohol and even by the weakest acids, such as carbonic, the precipitate, however, disappearing when a stream of air or oxygen is passed through it. Globulin itself, so called, as found in the blood corpuscles, crystalline lens, &c., is probably an alkali albuminate. (a) Vitellin. — Its solution is not precipitated by the addition of solid sodic chloride in excess. In the 3'olk of egg it is chemically associated in fome way with lecithin. It is prepared by digesting yolk of egg with water and ether so long as any yellow coloration is given ; the i-esidue is then shaken up with sodic chloride solution (10 per cent.), which dissolves it, and it is precipitated therefrom by the addition of an excess of water acidulated with a few drops of acetic acid. It may he i-apidly dis- solved lip again and reprecipitated, and afterwai'ds digested with alcohol, so as to purify it. Vitellin is a white granular body which is very soluble in dilute sodic chloride solutions, but not precipitable therefrom by saturation with solid sodic chloride, coagulating about 70° to 80° ; it is also very soluble in dilute hydrochloric acid ( jL per cent.) and in weak alkaline solutions. It is precipitated from its solutions by alcohol, and its neutral solutions heated to 75° are coagulated. {/3) Crystallin or Globulin. — This body is not })recipitate(l from its solutions by saturation with sodic chloride, thus resein- l)ling vitellin, but it is readily precipitated by alcohol. The crystallin- or globulin-like body precipitated from diluted serum by the cautious addition of acetic acid is said to differ from fibrinoplastin merely by the admixture of fibrin ferment with the latter (Wevl) ; but although crystallin corresponds very closely with fibrinogen and fihrinoplaslin, it has no pnwer, like them, in causing or assisting coagulation. Pre par alio a. — TIk^ lens contains several albuminoid bodies. If it is rubbed up witli washed sand and then digested with water a solution is r)b(;iin(;d of these ; after stirrinir well, filter. CLASSIFICATION OF ALBUMINS. ]07 and the paraglobulin can be separated by passing a current of carbonic anliycbide tlirough tlie liltered licpiid. This paraglobulin is also precipitated by dilute acetic acid, and when thus precipitated it is insoluble in water containing no air dissolved in it, but if some oxygen is passed through the water it soon forms an opalescent solution. On heating this solution to 93° a coagulum separates, but the tiltrate will not pass through clear unless some neutral salt of the alkalies has l)een added previous to heating. (7) Myosin, or Muscle Fibrin. — Its sodium chloride (10 per cent.) solution is precipitated by solid sodic chloride added in excess, or by extreme dilution with water. It is soluble in dilute hydrochloric acid, dilute alkalies, and neutral saline solutions. It is coagulated by heat (55° to 60°), and precipi- tated and afterwards coagulated by alcohol. After being dried its solubility is lessened. Between globulin and fibrin it is intermediate in its characters, like fibrin under certain condi- tions decomposing hydrogen dioxide, and giving a blue colour with the guaiacum test. ]Myosin is the name given to the solid body that separates in the coagulation of muscle plasma, and forms an elastic gela- tinous clotted mass. To obtain muscle plasma seA'eral large fiogs are bled, and their blood vessels are washed out with a sodic chloride solution (Go per cent.); the muscles are then removed, cut into pieces, and again washed in the salt solution, the temperature being kept down to 0°. The fi-agments are next tied up in a linen cloth, jjlaced in a tin or platinum crdcible inserted in a freezing mixture of eijual parts of snow or i)ounded ice and salt; when frozen hard the mass is cut into thin slices with a sharp knife that has been lying in the freezing mixture, and then pounded in a cooled mortar. Now tie up the broken muscle in a linen cloth, and express powerfully into a vessel surrounded by ice, the expressed fluid being filtered through a series of filters moistened with the saline solution (| per cent.) into a cold beaker ; and it is advisable to place the glass funnel in a larger metal funnel, filliug the space between with snow and salt. The preparation of ihe plasma by the above process requires much dexterity, and must be done rapidly, and the temperature kept low all the time. The muscles of frogs are used in pre- 108 NUTRITION ANT) FOODS. ference to those of mamma]?, on accomit of their coagulation setting in more slowly. The riiKScle juice is slightly yellow, opalescent, and syrupy, has a faint alkaline reaction, and coagulates at ordinary tem- peratures, becoming first a solid jelly and then separating into a loose and granular clot and an acid serum. The clot is myosin. The separation of myosin from muscle plasma is also readily effected by the addition of very dilute acids or sodic chloride, solutions above 10 per cent. The muscle serum, obtained by the separation of myosin from the muscle plasma, contains threa albumins — a potash albuminate like casein, precipitated by the addition of an acid at 20° to 30°; a serum albumin in large amount, coagulating at 75°; and an albumin or albuminate coagulable at 45° and insoluble in salt solutions. Myosin is much more easily jrrejyaTed in this way. Some finely divided muscle is thoroughly washed in Avater, and then triturated well in a mortar with a solution of ammonium chloride (12 to 15 per cent.) ; after several Jiours it is strained and subsequently filtered thi'ough jiaper, and the solution allowed to fixll drop by drop into a tall vessel filled with distilled water. The myosin separates in small fiocks (Daxilewskv). Syntonin is readily formed from myosin, a solution of the latter in a very small quantity of hydrochloric acid being con- verted into syntonin on heating it to 50°-55°. A reconversion can also be effected by dissolving the. syntonin in lime water, adding dry powdered ammonium chloride in excess, filtering, and cautiously neutralising the thick alkaline opalescent solu- tion with acetic acid. This solution behaves like a freshly pre- pared solution of myosin in ammonium chloride solution. (h) Fibrinogen (Metaglobulin j. — DenisTlasmin is probably a mixture of para globulin and fibrinogen. (s) Fibrinoplastin {Kuhne''s Pciraglohnlin, Panum\s Serum Casein). — Both these bodies comport themselves like myosin, but form fibrin when their neutral solutions are mixed in pre- sence of a special ferment. Like myosin they also decompose hydrogen peroxide. They are soluble in acetic acid, dilute alkalies, alkaline carbonates, and nculial saline solutions, and are re])recij>ilalcd 1 herefrom by carbonic acid or very dilute CLASSIFICATION OF ALBUMINS. 100 acetic acid (^',, per cent.) The solutions in dilute alkalies are not coagulated by heat, and the respective solutions of these two bodies in 1 to 5 per cent, sodic chloride solutions behave differently when heated — the fibrinoplastin coagulating at G8° to 70° or 75°, the fibrinogen at 52° to 55° (Hammakstenj. According to the same observer a further great distinction between these two bodies is, that paraglobulin is not altered by the action of fibrin ferment, while the fibrinogen is converted by its agency into fibrin. Where Found. — Fibrinoplastin is met with in the serum of blood after coagulation has occmrred, and is present in the cor- })uscles, chiefly the pale (in bullock's blood forming 3-58 per cent, and in rabbit's blood 1'26 per cent., Fkederic'q), also in lymph, chyle, pus, and some serons fluids, in connective tissne, and in the cornea. Fibrinogen exists in blood, chyle, and lymph, and in serous fluids generally, but particularly in hydrocele and pericardial fluids, the latter being specially rich in it. Some fibrinogen as well as serum globulin and albumin are present in dro])sical effusions. These do not, however, coagulate spon- laneously, but yield fibrin on the addition of fibrin ferment or on heating to 60°. Preparation. — i. Both bodies can be thus separated in succession fiuia llie Idood of the horse : Collect the blood, lay it a.side in the cold (below O'') fur :ui hour to allow the corpuscles to sink, and decant the plasma. Dilute this with ten times its volume of iced water, and then jiass a current of carbonic acid through it. The flocculent or some- ^vllat gniuular ]^l•^ci^)itatc is Jihrinojdastin. After decantation and filtration dilute the lilLratc with twice its volume of water at 0^, pa.ss moi'e carbonic acid, and neutialise with dilute acetic acid A viscous preei[)itate will be obtained of fibrinogen, which can be purified by washing it with carbonated Avater. The temperature must be kept down to freezing i)oint all the time. It will thus be seen that in l)repariug fibrinogen the fluid is more strongly diluted than in the preparation of fibi-inoplastin, and the current of carbonic acid must be passed for a longer time. By saturating the plasma with sodivmi chloride added in jjowder a precipitate is obtained containing both fibrinoplastin and fibrinogen. Wash the precipitate by decantation with saturated solution of .sodium chloride, and filter rapidly at a low temperatui'e. The filtrate will boju coagulate. 110 NUTRITION AND FOODS. II. FihrinojdasliH iiloue can be ])i'epared readily by tliluLing' serum with 15 times its volume of distilled water and adding a little dilute acetic acid (25 \)ev cent.) — about 3 or 4 drops of this to every 10 c.c. of serum employed. The diluted serum may likewise be pre- cipitated with excess of sodium chloride in powder. The fibrinoplastin thus oljtained possesses the greatest fibrinoplastic properties. Or dilute serum with ten volumes of water, and pass a stream of carbonic acid through it for half an hour, keeping the temperature as low as possible. Lay aside for 10 or 12 hours, decant carefully the supernatant liquid, filter, and wash the white, finely granular precipi- tate thoroughly with carbonated water. This operation is to be I'ecom mended. TIammarstex states that the whole of the fibrinoplastin is not ol)taincd by any of these methods, but he considers that this can be eflected by the addition of magnesium sulphate to saturation. But it is even doubtful whether the whole of the jwecipi- tates thus obtained should be termed fibrinoplastin. That they are of the nature of globulin there seems to be no doubt, so that if is capable of reacting with fibrinogen we may safely speak of it as fibrinoplastic globulin. It is insoluble in water and in concentrated saline solutions, but soluble in dilute saline and alkaline solutions, being precipitable therefrom by a current of carbonic anhydride or the addition of very dilute acetic acid. While the solutions in the dilute alkalies do not coagulate when heated, this occurs with the sodic chloride solution. III. Fibrinogen is more difhcult to prepare than fibrinoplastin. Hammahsten obtains it thus from blood : Collect the blood of a horse in a vessel containing a saturated solution of sulphate of mag- nesia — in the proportion of four volumes of blood to one of the saturated solution. Leave aside for several dtiys and filter ; add to the filtrate an equal volume of saturated solution of sodium chloi-ide, and the fibrinogen is precipitated. To purify it the precipitate is well pressed between folds of filter paper, redissolved in 6 to 8 per cent, sodium chloride solution, and reprecipitated by a saturated solution of the same salt : this process is repeated two or three times, when the precipitate will be free from paraglobulin and serum albumin. Fihriiiiiijr/ii, liorrevfiv, is iiiora cosily ]>re])arr,dfrom (i serous exuda- tion like hi/ilrucele fluid, by diluting tliis with ten volumes of water, and [)assing a stream of cirbonic acid through the diluted fluid for CLASSIFICATION OF ALBUMINS. Ill ;il)out lialf an hour. Tho same method of lu-eparation, therefore, applies to niniuogeu and fibriuoplastin, but with the former a greater di'gree of dilution is necessary, as well as a longer passage of tlie gas through the liquid. The same precipitate is also olitaincd by diluting the liydiocele lluid with 10 to 20 volumes of water, and exactly neutralising with very dilute acetic acid. The precipitate is flaky and viscid, and adheres to the walls of the containing vessel. It can likewise be separated ])y the addition of a mixture of acoliol (3) and ether (1). This fibriiioffeu is iiisdhible in wafer or saf mated solutions of stxliiim chloride or mai^nesiuni sulphate, but is soluble in dibit e solutions of the neutral salts of the alkalies and in very dilute solutions of the alkalies and alkaline carbonates. It is less soluble in these fluids than is fibriuoplastin, and is not altered to the same degree by repeated precipitations and solutions as is the case with paraglobulin, which is rendered insoluble and inactive by four successive precipitations with sodic chloride. But, like fibriuoplastin, it is precipitated £i-om its solutions by sodic chloride in excess. IV. TJia hlooiJ feriihPMt is prepared by mixing the blood serum of tlie ox \\itli 1.5 to 20 times its volume of strong alcohol, and filtering from 15 days to a month, or better even 3 or 4 months, after. The precipitate contains coagulated albumin and tlie ferment. This is dried over sulphuric acid, then finely powdered, and rubbed up with water for at least ten minutes, using 65 c.c. of water for every gram of powder. Filter, and in the filtrate will be found the ferment ; the filtrate is purified by treating it with carbonic anhydiide and shaking it in the air so long as any opalescence shows itself. The ferment may also be extracted by digesting the albuminous coagulum with glycerin. The ferment may be more easily prejiared by digesting washed bloodclnt in an 8 per cent, solution of sodium chloride (Gamgee). This ferment is most active about blood heat, V. The ■plasiiihi of Denis is a soluble substance existing in the blood plasma, and formed by the union in variable propoi- tions of soluble and insoluble fibrin, as Denis terms them, the vital action of the vessels under normal conditions maintaining these constituents apart. It is prepared by separating the corpuscles from the blooil plasma 112 XUTBiriON AAI) FOODS. by means of sodic sulphate, and adding crystals of sodium cblurido to the plasma. A soft white mass is obtained by filtration, and if this is shaken in 1(1 to 20 times its weight of water it will dissolve, but at the end of 10 to 15 minutes it will separate as a coagulum. All these bodies come most probably from the destruction of the pale corpuscles (Schmidt), though the red corpuscles no doubt also contribute. And it has been stated by Mantegazza that these pale corpuscles are the cause of coagulation, since when irritated by foreign bodies or inflamed tissues they set at liberty one or all of the generators of fibrin. The Generation of Fibrin. — According to Schmidt this bodv^ results from the combination of the fibrinogen and fibrino- plastin that are present in the blood in unequal pi'oportions, and remain separate till certain circumstances arise that bring about their union. But for this union to occur and coagula- tion be produced Schmidt states that there must also be present a ferment and a small quantity of salts, such as sodium chloride. Hammaksten affirms, however, that the fibrinogen obtained from hydrocele fluid can be coagulated in the absence of fibrino- plastin when a little calcium chloride and blood ferment are added. So that according to him there is only one generator of fibrin — that is, fibrinogen. Fredericq also states that the quantity of fibrin furnished by a solution of fibrinogen on the action of a ferment does not equal in weight the amount of precipitate given by the same solution when heated to 56°; and he has given proof that fibrinogen exists as such in living blood inside the vessels. This evidence therefore seems in favour of there hehifj hat one generator of fibrin, \iz, fibrinogen, which under favourable circumstances is decomposed or converted into fibrin, this con- version being apparently connected with the action of a ferment derivative of the pale corpuscles. in. FIBRIN.— 100 parts give C .... 52(5 H .... 70 N .... i6(;-i7-'i S . . . . l-2-l(> u . . . . 2\'J T2(\ CLASSIFICATION OF ALBUMINS 113 Tt yields 1-9 (o 2*1 per conl. of ash, consisling of jiliDsplialc of lime and a little magnesic phosphate and sulphate, carbonate of lime, and iron. About one-fourth per cent, can be obtained from normal blood. Fibrin is a white, elastic, more or less fibrillated solid, in- soluble in water and dilute solutions of sodium chloride ; it swells much in dilute acids, but less so in dilute alkaline solu- tions, the material thus swollen being coagulable by heat and dissolving readily in a pepsin solution. Fresh fibrin dissolves more or less slowly at 35° to 40° in dilute solutions of potassic nitrate (1 : 17), and in 10 per cent, solutions of sodic chloride and sodic sulphate, as well as in dilute alkaline solutions gene- rally — these solutions being coagulable by heat, and preeipitable by acids, alcohol, and excess of sulphate of magnesia in powder It is with difficulty soluble in dilute acids ; in 1 to 5 per cent, solutions of hydrochloric acid it merely swells up, not being dissolved, but at a temperature of 40° to 60° the solution is rapidly effected, or after several days at ordinary temperatures. When dissolved in strong hydrochloric acid with the aid of heat it forms a violet-coloured solution. When boiled with caustic potash it evolves ammonia, and potassic sulphide is formed. It decomposes hydric peroxide, so that if to oxygenated water a few drops of tinctm-e of guaiacum are added, and then some fibrin that has been steeped in alcohol, a blue coloration is developed. Or the same coloration can often be more characteristically obtained by placing on a piece of filter paper, moistened with freshly prepared tincture of guaiacum, a little fragment of fibrin that has been immersed in a solution of hydric peroxide or ozonised turpentine. Globulin, myosin, and fibrin form a series, myosin beino- intermediate in its characters between the other two. This is seen in their solubilities in dilute acids, alkalies, and neutral salts, fibrin being with difficidty soluble, myosin slightly soluble, and globulin on the other hand being easily soluble. Preparation. — 1. Fibrin is usually prepared by rapidly stirring freshly drawn blood with a bundle of tAvigs, and washing the filament- ous coaguluiu with walei', and then with alcohol and ether. I 114 XUTIUTION A XI) FOODS'. '2. Tlie fresh blood can also be well shaken in a Ixittle with several irregular jiieces of lead, and the fibiin adhering to the lead detached and treated as in 1. 3. Cut some coagulated blood into small bits, enclose them in a linen cloth, and leave the mass under an open cold-water tap for several hours, the mass being squeezed from time to time and the washing continued till all traces of red coloration have been remoA^ed. The resulting white fibrin is then immersed in sodic chloride solution for 3 days to separate any globulin, subsequently' for 14 days in dis- tilled water that is changed from d;iy to day, and finally digested with alcohol and ether. IV. ALBUMINATES {Derived Alb tcmins).— The native albumins are readily converted into one of these bodies by the gradual action of acids and alkalies, and the resulting compounds may be regarded respectively as acid and alkali combinations with the neutralisation precipitate. The solid albuminates are insoluble in water and sodic chloride solu- tions ; when freshly precipitated they are easily soluble in dilute acids, alkalies, and alkaline carbonates, and their soht- tions are precipitated by careful neutralisation, bat not by boUinr/, and only with difficulty by alcohol. Some of the acid albuminates contain sulphur, but the alkaline albinninates do not. (a) Alkali Albumin or Albuminate. — This body is present in all voung cohnn-less colls, in blood corpuscles and blood serum, and in the chyle; also in muscle, pancreas, nerve, lens, and cornea. It is possible thai several forms of il exist, judging from the. varying polarising power of different alkali alliuminates: thus when prepared from serum albumin by the actirobab]y identical witli serum albumin, and the other protalbin, a transition pro- duct formed during the pe})tonisation of various albumins with alkalies and pancreHtin. It is this protalbin, they say, that imparts lo casein its acid character. Casein of woman's milk is slightly ditrercnt from that of CLASSIFICATION OF ALBI'MINS. 137 cow's milk, lieing only parlially precipitated by «icetic acid and carbonic acids, and appearing in greyish white flocculi instead of in lumps. There is a sh'ght difference also in their percentage composi- tion. f':i!-oiM (Woman) (Cow) (J 52-35 53-62 H 7-27 7-42 N 14-65 14-20 O 25-7:{ 24-76 (MAaJIIS) The casein of cow's milk is also more soluble in wat-er and alcohol than the casein of woman's milk. To separate casein from skimmed milk, dilute the latter with 10 times its volume of water, aud add a few drops of dilute hydiocldoric or acetic acid until a precipitation begins to occiu" ; now pass a cuirent of carbonic acid, filter, and wash the eoagulum with cold water, and afterwards with alcohol and ether ; or, to render it purer, after the cold water wash it with water acidulated with hydrochloric acid, and subsequently with pure water. Now heat to 45"^ with a large volume of water, when it will in gi-eat part dissolve ; filter, and pre- cipitate the dissolved casein with carbonate of ammonia. Collect the precipitate and wash it with ^\■atel■, and then with warm spirits and ether. WitJi, human milk it is better to precipitate the casein with sul- phate of magnesia added to saturation to the milk warmed to 30°, to wash the separated casein with a saturated solution of this salt, and then with alcohol anil ether. To purify it redissolve in water, and dialyse to separate the magnesic sulphate completely. A nearly pure solution of casein is also obtained by dialysing milk 30 to 3G hours (Schmidt). (7) Acid Albuminate {Sijntonin,Albumosfi). — The majority of acids in the dilute condition and at ordinary temperatures transform albumins into acid albumin, which is also the first product of the action of gastric juice on proteids. The conver- sion is accelerated by raising tlie temj^erature. The term acid albumin has generally been applied to the combination with acetic acid alone (but this, we see, is incorrect), and fir/ntonin to the combination with hydrochloric acid, especially when myosin bas been employed. This is the percentage composition of the syntonin : C o4-l, H 7-3, N IG-I, 21-5, S M. 118 NUTRITIOX AXD FOODS. An acid albuminate is a white gelatinous substance insolu- ble in water and sodic chloride solutions, but easily soluble without alteration in very dilute hydrochloric acid and dilute caustic alkalies. Its solutions have a specific rotatory power for yellow light of —72°, which rises to —84*8° when the solu- tion is heated in a closed vessel. Acid albumin solutions are precipitated by neutralisation even in presence of sodic or potassic phosphate, also by satu-. rating them with sodic chloride, acetate, or phosphate ; but they are not affected by boiling. The solution in lime ivater is, howeve7\ 'partially coagulated by boiling, and a still further precijAtation occurs after boiling on the addition of sodiimi chloride or magnesium sulphate. Indeed, a precipi- tate is generally produced on boiling an alkaline solution of any acid albumin to which magnesic sulphate has been added in excess. Preparation.- -Digest egg albumin or dissolve sernm albumin in fuming hydrochloric acid, and let it stand till the solution is bluo- coloured ; then dilute with twice its volume of water. Collect the ])recipitate, dissolve it in water, and carefully neutralise the solution with sodic carbonate ; finally wash well with water. To prepare syntonin, finely divided muscle as free from fat as pos- sible is well washed and placed in one-fifth per cent, hydrochloric acid, which dissolves it readily ; the solution is filtered after a few hours, and the opaline, slightly viscid filtrate diluted and exactly .saturated with sodic carbonate : gelatinous flakes are obtained, whicli ai'e to be washed in water. Tests. — 1. A solution on boiling remains clear ; then acidify strongly with acetic acid and add a saturated solution of sodic chloiide until a precipitate appears. On heating the precipi- tate disappears ; now add more sodium chloride, and a point will soon be reached when boiling will no longer clear up the mix- ture, and the albumin will be completely precipitated by the sodium chloride. 2. Pure nitric acid gives a precipitate wliich dissolves with an intense yellow colour on heating. 3. Add caustic sotla, and then a drop or two of a weak solution of cupric sulphate ; an intense purple violet colour is ])roduced. CLASSIFICATION OF ALBUMINS. 119 4. With Millon's reagent a deep red colour is given on heat- ing, but the presence of much sodium chloride interferes with the reaction. 5. To separate this body from fluids containing it, boil them with hydrated oxide of lead (Hof.meisthr). V. PEPTONES. — The gastric juice converts albuminous bodies into pe[)tones ; pancreatic juice likewise possesses the same property, and possibly also the intestinal juice, but to a limited degree. All proteids, in short, except amyloid sub- stance yield peptones with acid gastric or alkaline pancreatic juice at the temperature of the body. It is said, further, that they are produced by the prolonged action of dilute acids at high and of moderately strong acids at medium temperatures, also by the action of water at very high temperatures and pres- sures. In all these cases it is probable that an albuminate is first formed. All proteids are also said to be converted into peptone by prolonged contact with animal and vegetable tissues, the conversion of swollen fibrin into peptone by the action of the tissue of the lungs or kidneys taking place as energetically as under the influence of pepsin (Eichwald, Poehl), and it is well known that the juice of the so-called carnivorous plants ((Irosera, &c.) when acidified with hydrochloric acid (one-fifth per cent.) dissolves fibrin as rapidly as does pepsin itself. In the decomposition of albumins by bacteria peptone is also one of the early products. Peptone has been found in the liver and spleen in leukae- mia, and in certain pathological urines it is occasionally present. The peptones are said to possess a slightly different compo- sition from the albumins from which they were derived in con- taining a smaller proportion of carbon and nitrogen. They seem to result from the fixation of a certain quantity of water with the albuminous matters. Maly, however, regards the peptones as possessing the same elementary composition as their derivative albumins. In the subjoined table three analyses of fibrin are given, and three of fibrin peptone: — 120 NUTRiriON AND FOODS. Fibrin Peptone MUNK KlS-l-IAKOWSKI KOSSEL Maly c .51-40 52-.-) 1 52-32 46-67 48-97 51-40 II . . . G-9.5 (;-98 7-07 7-12 7-06 0-95 N . . . 17-13 17-34 lG-23 16-30 15-14 17-13 S ... 1-13 1-18 1-35 0-93 1-16 — . . . — — 23-03 28-98 27-67 — Peptones have also been regarded as due to the swelling up of the colloid of albumin, the inner constituent remaining the same, no change in specific gravity, rotatory power, or index of refraction taking place in the conversion (Poehl). But the proportion of salts in peptone is undoubtedly smaller than that of the albumin from which it was derived ; thus in serum albumin the salts are = 9-6 per cent., in egg albumin = 5*43 per cent., in fibrin = 2'17 per cent., but in peptone only = 1-16 per cent. By the digestion of fibrin MoHLENFELD obtained a peptone having the composition Ci^gHgQjN^pSOgj' It is evident, therefore, that at present we cannot say that any constant ditference has been conclu- sively established, although there is a slight probability in re- garding peptones as hydrates of rdbumin. Different peptones have been described, but those given by Meissner cannot all be regarded as true peptones. Kuhne distinguishes hemipeptones and antipepAones, the former being readily capable of conversion into leucin and tyrosin under the action of trypsin, while antipeptones resist this decomposition. Between the genuine proteids and the peptones there exist gradual states of transition, depending only on different states of hydration, a peptone being caj)able of reconversion into pre- cipitable albumin by treatment with dehydrating agents, such as alcohol and salts of the alkalies ; and by heating a peptone for some hours to 130^— 140° it changes more or less com- pletely into albumin (Henninger). Preparation. — 1, Some freshly jjrepared fibrin is to be cut up very fine aud covered with 5 to 6 times its volume of hydrochloric acid (one-fifth j)er cent.). As soon as the fibrin has assumed a transparent !i.Hpc(;t ;id. Iiisolul)l(' in dilute acids and alkalies, but easily soluble when digested with gastric or pancreatic juice, forming peptones. Coagulated Albumin. — The protein reactions are easily ol)tained witli the dry solid. C. Insoluble in water, sodium chloride, dilute acids, or gastric juice ; soluble in the stronger alkalies and in strong hydrochloric acid. Antylo'ld Substance. — Gives a I'cddish colour with iodine, a blue with iodine and sul[)huric acid, and a rosy reil with methyl violet. chaptp:r XX. THE COLL AG ENS. TiiKSE bodies are closely allied to the albumins, Init when treated with acids or dilute bases they do not, like them, yield syntonin. Ossein and gelatin are types. They are poorer in carbon, but mostly richer in nitrogen than the albuminoids. A common property possessed by them is that of their hot aqueous suluttons solidifyinfj into jellies on cool'nirj. The alimentary value of gelatinous bodies is still involved in some uncerlainty. They are stated by INIajendie and others to have no alimentary value, but others again are of opinion that they possess real nutritive i)roperties, to some extent forming a subsiituie for other plastic material, and therefore by their aflmixture witli the food admitting without disadvan- tage of a diminution in the proteids (BisCHOFF and Voir). Even elastin,itis now stated, is diss<:>lved by the gastric juice, furnish- ing peptone (Etzingee, Horbaczewski ). Percentage composi- tion C 499 u 7-3 N 17-2 S Authority O.^sein 24-9 0-7 Fkemy and Verdeil Gelatin 500 6-5 ' 17-5 25-4 0-6 „ SCLIEPEE r49-3 66 14-4 29-3 0-4 Mulder 147-7 6-7 13-8 310 0-6 Landwehr Mucin 52-2 7 12-6 28-2 — HOPPE Seyler Elastin . /55-5 7-4 16-7 20-4 — io^■■^ 6-9 16-7 21-4 — Horbaczewski 128 XUmiTIO^' AND FOODS. The chief collagens are ossein, rjelathi, and cJioiulrlii ; an allied body is mucin, and accordingly for convenience sake it will be described at the same time, as also elastin. 1. GELATIN {GllLtin).—^\hen some dried and purified powdered bone is digested with dilute hydrochloric acid (10 per cent.), the earthy salts will be slowly removed and the body called ossein will remain behind. Dry bones yield 29 to .30 per cent, of this body. It is insoluble iu water, hot or cold, but when heated in a Papin's digester it is dissolved and yields gelatin ; indeed, ossein and gelatin have almost the same com- position, and by boiling ossein withi w^ater it is very rapidly and completely changed into gelatin. It does not, however, yield glucose when boiled with acidulated water. Collagen is the name given to the substance of which white hbrous connective tissue consists, although it is not present in their embryonic condition. The action of boiling water con- verts it into gelatin. After 30 hours' boiling collagen no longer gelatinises, but is resolved into two peptones, one insoluble iu alcohol and precipitated by platinic chloride (semigliUin), the other soluble iu alcohol but precipitated by the platinum salt (Jiemicollin) — Cjo^Hi^gNgjOgg {collagen) =^^^^^^^0^, {semi- glutin) + C^JT^oNj^Oig {Jiemicollin) (Hofmeister). To prepare the collagen pieces of tendon are sliced thin, soaked for some time in cold water, then for several days iu weak lime or baryta water ; afterwards washed in water, then in very dilute acetic acid, and again in water. The residue thus obtained is collagen mixed with some elastic tissue. The collagen and ossein appear to be closely allied, if not identical. Long-continued boiling of white fibrous tissue, skin, or bone yields, as we have seen, a watery solution of gelatin. Gelatin is later in its appearance than either muciii or chondrin, for while certain embryonic tissues yield mucin and chondrin on boiling, they give no gelatin, though this replaces thcni when these tissues have undergone development. Pure f/elutin is prepared from commercial gelatin by soaking the latter several days in distilled water, which is changed from time to time. It will then have swollen up considerably, and is next to ha dissolved in distilled water with the aiJ of heat. AfUir the solution riTE COLLAGE'SH. Vy^i has stood some time, to allow any sediment present to fall, it is filtered hot into 90 per cent, alcohol, when the gelatin will separate in thready masses. These are to be collected, cut fine, and dried, first in the air and then over a water bath. It is also readily prepared by dis.solving isinglass in dilute hydro- chloric acid, and dialysing the solution. Properties. — In the pure state gelatin is slightly yellowish . or almost colourless, transparent, vitreous, and tasteless ; it swells in cold water without dissolving, but is readily soluble in liot water or hot glycerin, the solution settinrj or gelatinising on cooling, even one-tenth per cent, solutions possessing this property ; but long-continued boiling, either alone or after the addition of a little nitric or acetic acid, or heating up to 140° in a sealed tube, destroys this power of setting. Gelatin is soluble in dilute acetic or other acids, but is insoluble in oils, alcohol, and ether. Its watery solutions polarise to the left (about 130° at 30°). Solutions of gelatin take up more calcic phosphate than does pure water. Its alkaline solutions dissolve cupric oxide with a violet colour, which on long boiling becomes yellowish red, but without any separation of reduced oxide, as this is solu- ble in alkaline gelatin solutions : its presence, therefore, inter- feres with Trommer's test for sugar. In the direct sunlight gelatin combines with potassic chro- mate, forming a yellow, insoluble, amorphous mass. Derivatives. — As the result of putrefaction gelatin is de- composed, and among the products we have a little leucin and much glycocin, ammonia and some of the fatty acids also being present, but no tyrosin. Wh<'n 1 part of gelatin is boiled with 4 parts of sulphuric acid and 12 parts of water for 36 hours, excess of milk of lime or baryta then added, the whole boiled and filtered, the filtrate acidified with sulphuric acid, again filtered and evaporated to a small bulk, granular crystals of glycocin or amido-acetic acid (CjH-NOg) will be obtained. These form rhombic transparent l)risms that possess a sweetish taste and are insoluble in alcohol and ether. By the prolonged action of hydrochloric acid at 38", or of acid pepsin, a gelatin peptone is obtained which is diffusible but no longer gelatinises. K 130 NUTRITION AND FOODS. Further, if boiled some hours with strong caustic potash, then neutralised with sulphuric acid, evaporated to a small bulk, and the residue extracted with hot alcohol, leucin will be obtained on evaporating the alcohol. Tests. — 1. Gelatin solutions are precipitated by mercuric and platinic chlorides, tannic acid, alcohol, and chlorine water, the precipitates being more or less viscid and slimy, separating im- perfectly, and insoluble in alcohol, ether, and water, but soluble in the alkalies. With the mercuric chloride and tannic acid the precipitates are insoluble. 2. G-elatin is not precipitated from its watery solutions by acids, acetate of lead, or by alum. 3. By its property of gelatinising it is possible to identify gelatin if its solution is not too dilute. 4. Gelatin is distinguished from a proteid by giving no pre- cipitate with acetic acid and potassic ferrocyanide, or with most metallic salts ; and from chondrin by not being precipitated by acetic acid. Watery solutions polarise to the left to a less ex- tent than solutions of chondrin. II. CHONDRIN. — When the permanent cartilages are boiled chondrin is obtained as the product ; it is derived from the intercellular substance and the capsules, but not from the cells themselves. A somewhat similar body is obtained by boil- ing the cornea. The name chondrogen is given to the material of which this intercellular substance is composed, just as the name collagen is applied to the constituent principle of white fibrous tissue which yields gelatin on boiling. Preparation. — Boil some costal cartilage for about half an hour, then detach the perichondrium and cut the cartilage into as small pieces as possible, which are to be macerated some hours in cold water and then heated up to 120° for two or three hours in a Papiu's digester under a pressure of two or three atmospheres, or boiled instead for 24 to 48 hours or so at ordinary pressures. Filter the hot extract rapidly, evaporate the filtrate, and after treating the residue with cold water dry and reduce it to powder, and having boiled it with alcohol dry it again. Or acetic acid can be added to the filtrate, and the precipitated chondrin can be exhausted with alcohol and ether, and then dried (Hoppe Seyler). Properties. — Dry chondrin forms a hard, translucent, yellowish THE COLL AG ENS. 131 mass, insoluble in alcohol and ether, swelling up in cold, but dissolving in hot water and alkaline solutions. Like gelatin the solution of ehondrin in hot water sets when the solution cools, but by prolonged ebullition, or by treatment with alkalies, solu- tions of both bodies lose this property. A watery or alkaline solution has a polarising power = —213-5°, but as high as — 552° with excess of alkali (Hoi'PE Seyler). Derivatives. — Chondrin is chjsely allied in its characters to gelatin, as they both, when decomposed by boiling with baric hydrate, gi\e the same products, except that chondrin yields three times as much acetic acid as gelatin ; but when decomposed with sulphuric acid chondrin only yields leucin and little or no tyrosin and glycocin. Chondrin also, on being boiled a long time with hydrochloric or sulphuric acids, or when digested with gastric juice, furnishes a substance resembling an acid albumin, as well as a nitrogenous body (chondroglucose) capable of reducing cupric sulphate in alkaline solutions, crystallising and fermenting, however, with difficulty, and polarising to the left (Bodeckek) ; accordingly it may be regarded as a nitrogen- holding glucoside. In this respect mucin resembles choudi'in. Chondrin can be changed into gelatin under the influence of oxidising agents (Brame) ; and in the organism a similar change occurs, as when cartilage, yielding chondrin, gives place to bone, yielding gelatin. But chondrin is something more than 3 per cent, poorer in nitrogen than gelatin. In spite, however, of these points of difference there seems some proba- bility in MoROCHOWiTz's opinion that chondrin and gelatin are identical, chondrin only differing from gelatin in being a mix- ture of this body w^th mucin and salts. Characteristics and Tests. — 1. Chondrin as well as gelatin are distinguished from albumin in that their solutions in acetic or phosphoric acids are not precipitated by potassic ferrocyanide, and they are both precipitated by alcohol and chlorine water. 2. Dilute mineral acids precipitate it readily, but the pre- cipitates are readily soluble in excess. 3. The Organie Acids. — Aceticacid gives a white precipitate, which is insoluble except in a very large excess ; but the pre- cipitate does not occur in presence of neutral salts of the alka- lies or alkaline earths, and sometimes not with impure solutions. X 2 132 NUTEITIO^' AND FOODS. Tartaric, citric, and oxalic acids have the same action, but the oxalic acid precipitate is soluble in excess. Tannic acid gives no precipitate, only an opalescence. 4. The salts of 'tnostof the heavy metals, as lead, copper, silver, and iron, give precipitates that are wholly or partly soluble in excess. The lead precipitate is insoluble in excess, and no pre- cipitate, but only an opalescence, is given with mercuric chloride. 5. Alum, which gives no precipitate with gelatin, precipi- tates chondrin, but the precipitate disappears on the addition of excess of alum. III. MUCIN. — This body is contained in the cement sub- stance of the connective tissues, but it is specially abundant in the embryonic condition of these tissues and in the jelly-like variety ; it is met with also in the cement between the cells of the epidermis, and is likewise one of the excretion products of the protoplasm of the ej^ithelial cells lining mucous surfaces, and of the secreting mucous cells of the submaxillary and sub- lingual glands ; it is further largely present in the bile. Its structure is unknown, and the comj)osition assigned to it varies, but, according to Eichwald and Scherer, its average percentage composition may be taken as C = 49-5, H=:6'7, N = 9"6, 0=!:34-2. Dry mucin yields about 2*44 per cent, of ash, and contains no sulphur. Mucin is a nitrogenous glucoside, and it is probably an albumin derivative. Hoppe Seyler, indeed, now classifies it with the albumins. Preparation. 1. — Cut the suhmaxlllary glands of an ox into small pieces, and after washing these in a little water digest them for some time in water, then filter and precipitate the mucin in the filtrate with acetic acid ; collect on a filter and wash thoroughly with water ; next dissolve the precipitate with milk of lime, filter, and add acetic acid ; the mucin thus precipitated is to be washed with water, and then with alcohol and ether in succession. Or the cleaned glands are minced and rubbed up with powdered glass, the mass covered with water and filtered after 12 hours, and the extraction repeated. The filtrate is precipitated with excess of acetic acid, the separated mucin washed with water and a little acetic acid, then with warm alcohol, and finally dried (Obolensky). 2. Digest finely-divided tendon with distilled water, and then with large quantities of lime or baryta water, from which the mucin is sub- THE COLLAGENS. 133 sequently precipitated by acetic a(;itl ; filter and wash the precipitate with water and dihite spirit (Rollett). 3. To extract mucin from bile add to the bile its own volume of spirit (85 per cent.); the mucin is precipitated; separate it by de- cantation and wash with more spirit. Dissolve up the mucin in lime or Baryta water, filter after some time, and reprecipitate by excess of acetic acid ; collect on a filter, and wash it there with water, alcohol, and ether. Properties. — jNIucin generally presents itself in white or yellow thready and tenacious masses. It swells up in water without dissolving, but being readily miscible with it ; if boiled with the water, however, for some time, a little of the mucin enters into imperfect solution. It is soluble in dilute hydro- chloric acid (5 per cent.), in pancreatic juice, and in weak alka- line solutions, but insoluble in alcohol, ether, chloroform, dilute acetic acid, very dilute mineral acids (1 per cent, hydrochloric), or gastric juice. Acetic acid causes it to shrink, and caustic potash renders it at first more thready and then dissolves it- Its neutral solutions are not coagulated by heat, and to these solutions it communicates a certain degree of viscosity, even when present in small amount. Its solutions are precipitated by alcohol, alum, basic acetate of lead, acetic acid, and the dilute mineral acids, being soluble, however, in excess of the last ; they are not precipitated by cupric sulphate, mercuric chloride, or potassic ferrocyanide, but when the last salt is added to a boiled solution of the mucin in glacial acetic acid a white precipitate is formed. Mucin gives a rosy red coloration with Millon's reagent, and a yellow colour with nitric acid. Like grape sugar its pre- sence renders the precipitate given by the caustic alkalies with cupric sulphate soluble in excess, but leads to no change of colour on boiling the solution. Derivatives. — Mucin is decomposed when boiled with a dilute mineral acid like sulphuric into an acid albuminoid material and a body like sugar in its reducing powers, but not fermentable (Eichwald). When boiled for a considerable time with sidphuric acid diluted with its own weight of water, leucin and tyrosin are obtained in abundance, as well as about 7 per cent, of the compound ammonias (Stadeler). Eichwald's 131 NUTRITION AND FOODS. mucin peptone is obtained by dissolving mucin in excess of lime water, boiling the solution until it gives no precipitate with acetic acid, then passing a current of carbonic acid gas through the solution, filtering, evaporating the filtrate to a small bulk, and precipitating with alcohol. In the annexed table gelatin, chondrin, and mucin are com- pared. Gelatin Chondrin 1 Mucin 1. Acetic acid . Gives no precipi- A precipitate solu- A precipitate not tate, but dissolves ble in solutions soluble in solu- in the acid ; is of tlie alkaline tions of the alka- precipitated from salts line salts its solution when warmed with the alkaline salts 2. Mineral acids No precipitate A precipitate solu- A precipitate solu- ble in excess and ble in excess in neutral saline and alkaline solu- tions 3. Tannic acid A yellowish preci- Only an opales- — pitate cence 4. Acetate of No precipitate A heavy precipi- Precipitated by lead tate, partly solu- basic acetate of ble in excess lead 5. Alum . . No precipitate 1 xV precipitate solu- ble in excess A precipitate 6. Me re uric An abundant white No precipitate, only Onlj' a slight tur- 1 chloride precipitate an opalescence bidity 7. When flecom- Leucin and gly- Leucin, but no Leucin and tyro- posed by cocin formed ; glycocin formed ; sin and a body boiling di- no sugar also chondroglu- lilce chondroglu- lute acids cose * cose make their appearance ratholofji/. — In certain abnormal affections included under the term myxcedema, there is generally observed a jelly-like swelling of the connective tissue, due in part to an increase in its cement sub- stance (Ord). To obtain tliis mucin, mince the skin finely and digest with water for several days, filter, and precipitate the filtrate with excess of acetic acid ; separate the precipitate after several hours have elapsed, then dissolve it in lime or baryta water, and after twenty-four hours reprecipitiite witli acetic acid. The precipitate thus obtained is to be washed with water, alcohol, and ether, and subsequently dried. It is sometimes an advantage to immerse the skin in methylated spirit for several days, and then to digest at once in baryta water. THE COLL AG ENS. 1S5 IV. ELASTICIN or ELASTIN is the name given to the substance composing the libn-s of yellow elastic tissue. Al- though it is very closely related to keratin it will be described here for the sake of convenience. To pnqiare it cut the ligamentum niichae of a giraffe, lioi-se, or ox into thin pieces, and exhaust them successively with ether, hot alcohol, hoiling water, strong acetic acid, and 1 per cent, caustic soda, allow- ing the boiling in the water to continue for at least 36 hours, or for a shorter time at a tempemture of 120° in sealed tubes, and for about 6 houi's in the acetic acid. After the action of the soda the tissue remaining is again boiled with dilute acetic acid, then well washed in water, and afterwards placed 24 hours or so in dilute hydrochloric acid to neutralise the alkali ; finally the acid is removed by washixig the residue in hot water. Properties. — The elasticin thus obtained appears as a brittle yellowish mass, which recovers its elasticity and fibrous appear- ance if soaked in dilute acetic acid. If digested for 12 hours or so with strong boiling caustic potash a brownish solution is obtained, which, if neutralised with sulphuric acid, will give a precipitate with tannic acid. It dissolves in strong nitric and sulphuric acids, and the solution, if warmed, yields 30 to 40 per cent, leucin but no tyrosin. The percentage composition of elastin (C 54*32 ; H 6*99 ; N 16*75; ash 0*5 — Etzinger) as well as some of its reactions, such as the red coloration with Millon's reagent, seem to indicate its derivation from, and its close connection with, the albumins. CHAPTER XXI. LEUCIN AND TYROSIN. These two bodies, which are important proteid derivatives, will be here described in detail. LEUCIN, or Amido-caproic Acid [CgH, ,(NH2)02 or CgH.gNOg I p XT ]eTr -1 L " = ' pQ AVr ^ , belongs to the fatty bodies and is found in many of the organic tissues, particularly the pancreas, spleen, thymus, salivary glands, and also in the lungs and brain. It is a 136 NUTRITION AND FOODS. constant decomposition product of albumin and nitrogenised substances, as horn, &c., and can be obtained from any of these by the action of alkalies or acids, or as the result of trypsin diges- tion or of decomj^osition. If cheese, for example, is moistened and allowed to decompose, leucin will be formed, and can be removed from the decomposing mass by the action of water. T}a-osin frequently accompanies leucin, particularly in urine, but the gelatinous tissues furnish no tyrosin. Preparation. — 1. Digest the following mixture for 6 hours at 45° : fibrin and bullock's pancreas 1 kilo, each, water 6 litres, thymol 4 to 6 grams. Then boil and acidulate with acetic acid, filter, and evapo- rate the filtrate, when leucin and tyrosin will separate. The deposit is to be collected, and by heating it with water leucin, which dissolves I'eadily, can be separated from the tyrosin, which is not so soluble. 2. Shavings of horn form an easy source. Boil a quantity of these shavings for 3 or 4 hours in twice their weight of dilute sulphuric acid (20 per cent.) in a vessel connected with a condenser; then treat with excess of milk of lime or chalk, and boil again for the same period as previously ; now filter, and after the addition of a slight excess of sulphuric acid filter again. The filtrate concentrated by evaporation is set aside to crystallise. Purify the crystals by boiling them with water and lead hydrate, filter, pass sulphuretted hydrogen through the filtrate to separate the lead, filter agam, and evaporate the filtrate to dryness. The residue, when dissolved in boiling dilute spirit, and the solution cooled and evaporated down to a small bulk, will give crystals of leucin, 3, Fuse dried albumin with its own weight of caustic potash, and when a well-marked yellow colour is attained allow the mass to cool, and then digest it in water ; filter after some time, acidify the filtrate .slightly with acetic acid, and concentrate to a small bulk : tyrosin is first deposited, and then leucin (Bopp). Properties. — It generally presents itself in white shining lamella.', that are fatty to the touch, insoluble in ether and chloroform, easily soluble in alkalies and acids, but more soluble in the same fluids when boiling. Leucin is not very soluble in cold water or spirit. It crystallises from its aqueous solutions in slightly refracting, more or less brown -tinted spherical masses, that exhibit a fine radial striation often associated with the appearance of concentric rings ; these balls are made up of a great series of concentrically grouped, very thin, white, glisten- ing plates or fine needles. Wlien pure, the crystals are gene- LEUCIN AND TYROSIN. 137 riilly flat, thin, and white ; but the rounded lumps are more frequent when the leucin is at all impure. It sublimes unchanged at a moderate heat with the odour of amylamine, and condenses in woolly masses consisting of ex- tremely thin rhombic plates, grou])ed in rosettes. Leucin forms easily soluble salts with hydrochloric, nitric, and sulphuric acids; it combines also with the salts of lead and silver. Fi<;. 15. — Crystals of Leucis (Dikkkrext Fuums). (Crj'Stals of kreatiiiin cliloride of zinc resemble the leucin crystils depictetl at a.) The crystals figureil towards ilic right consist of comparatively impure leucin. Tests. — 1. Place a few crystals on platinum foil, add a drop of nitric acid, and evaporate gently ; heat the colourless residue after the addition of a few drops of caustic soda : a yellow or brown mass is obtained, which forms an oily drop (Scherer). 2. Boil a dilute solution with excess of cupric hydrate, and on cooling bright violet scales are deposited. To Detect in Urine. — Evaporate the urine to dryness ; treat the. residue witli cold absolute alcohol and then extract it with boiling spirits : leucin crystallises from this on cooling. Examine the deposit under the microscope after 24 hours. The leucin balls may be con- founded with those of urate of ammonia, but the latter have a darker contour and are scarcely soluble in alcohol. The deposit may be dis- solved in water, basic lead acetate added in excess, filtered, and sul- phuretted hydrogen passed through the filtrate to separate excess of lead ; the filtrate from this last is evaporated to dryness, and the residue boiled with strong spirit, which dissolves up the leucin but deposits it on cooling. A little of the leucin thus prepared is to ))e carefully dried and sublimed in a small tulje : it is deposited in woolly masses, part of it, however, being decomposed and evolving the smell of amylamin. 133 yUTIilTIOX AyD FOODS. To Separate Leucin from Organs vu which it is Contained. — Cut up the oi'gan (a pancreas, for example) into little bits, add water, and rub up thoroughly with finely broken glass in a mortar ; now express firmly through a cloth, and having acidified the watery extract with acetic acid, boil and filter to separate the precipitated albumin ; add basic acetate of lead to the filtrate, filter again, and sepat-ate any lead in the filtrate wdth hydric sulphide. The filtrate from the last is evaporated to a syrup, treated with strong boiling alcohol, and tha alcoholic extract evaporated to dryness. Pathology. — Both leucin and tyrosin may present them- selves in urine in acute yellow atrophy of the liver, and in malignant jaundice the crystals of both bodies may be found in the hepatic veins. In the urine it may also be met with in severe cases of t}phus and variola (Winiwarter), and in acute phosphorus poisoning ; occasionally also after epileptic fits and brain injuries, and in leucocythsemia. In a few cases both bodies have been seen in the saliva and bile. ber of the aromatic group derived from benzene (CgHg). It may be regarded as an alanin in which hydrogen is replaced by ox3'^phenol. As a normal constituent of the body it does not probably exist except as a product of pancreatic digestion (Radziejewsky). Almost all proteids furnish this body under the action of strong oxidation agents ; thus it is obtained by the decompo- sition of albumin, gelatin, honi, elasticin, and mucin under the action of acids and alkalies, and by the pancreatic digestion of albumins, &c. ; it has likewise been prepared synthetically (Erlenmeyer). Preparation. 1 . From Horn Shavings. — Boil 1 kilo, with 2 kilos, strong sulphuric acid and 10 kilos, water for 16 hours ; dilute the hot mass with three times its volume of water, and neutralise with thin milk of lime; filter and wash the precipitate with boiling watei\ Evaporate the filtrate and washings to half their volume, acidify with sulphuiic acid, and filter again ; add acetate of lead in excess to the filtrate, filter, pass hydric sulphide through the filtrate, and after having boiled for some time throw upon a filter, and evaporate this last filti-ate until crystallisation begins, assisting the process by the addition of some acetic acid. To purify the crystals dissolve them in LEUCll^ AXI) TYROSIN. 139 Wiiter, treat the .solution witli acetate of lead, separate the lead by a current of sulphuretted hydrogen and subsequent filtration, and evaporate the filtrate ; the crystalline residue may be further purified by recrystallisation from ammoniii. 2. PrejKiratinii hy Pancreatic Digestion. — Take the panci-eas of an animal that has been killed some 5 or 6 hours after a large meal, dry it rapidly between some folds of blotting-paper and weigh it ; then cut it into pieces and rub up in a mortar with 10 times their weight of raw fibrin; now add about 15 times the weight of the mixture of warm water (45°), and transfer the whole to a hot chamber the temperature of which is steadily maintained a little below 50°, the mixture being stirred from time to time ; and after 5 hours or so any albumin present is separated by acidifying with acetic acid, boiling, and filtering through linen. Tlie filtrate is to be quickly reduced to a .syrup by evaporation, poured hot into a fla,sk, and alcohol added till an evident precipitate is formed. Filter after some time and evaporate the filtrate to a small bulk. This concentrated filtrate must now be set aside in a cool place for a couple of days, and then the precipitate is to be collected on a filter and washed with cold water. Leucin and tyrosin are both present in the cry.stalline mass. By washing the deposit well with water at 50° the leucin is separated, and by dissolving the residue in hot water and repeatedly cr} stallLsing this deposit from its solution in ammonia the tyrosin will be obtained in tolerable purity. Properties. — TjTosin appears mostly in fine, long, white, silky needle.s, occurring generally in sheaf-like bundles or //■III Fig. 16.— Tyuosi.v Cuy.stals. rosettes, but appearing frequently as a deposit of yellowish green crystalline globules, which dissolve in hot dilute ammo- nia, but are deposited on cooling the solution in hrilUant 140 XUTItlTION AND FOODS. colourless oieedles, geneoxdly grouped in radiated stars. The crystals somevchat resemble those of hypoxanthin. Heat decomposes it, so that it does not sublime like leiiciu. It is insoluble in absolute alcohol and ether, almost insoluble in cold water, and slightly soluble in hot water, but readily soluble in the mineral acids, in warm dilute ammonia, and the other alkalies and alkaline carbonates ; soluble, however, with dijBBculty in acetic acid. It combines with acids and metallic bases, as C.H^NOg.HCl, CgHioNaNO^, and CgHioAgNOg. Tests. — ^1. Pour a few drops of strong sulphuric acid over a little tyrosin in a porcelain dish or a watch glass ; heat gently for some time over a water bath, and lay aside covered for half an hour ; then dilute with water and satm-ate by rubbing it with a little carbonate of lime or baryta, filter, and evaporate to a few C.C., and filter again from any carbonate of baryta that may separate. Now treat the filtrate with a little very dilute neutral ferric chloride solution, and a marked violet colour appears (PiRiA). 2. Treat a hot watery solution with a few drops of Millon's reagent, carefully avoiding excess, and boil a few minutes : a rosy or a dark red colour appears, and if the solution is concen- trated a dark red precipitate may be formed (Hoffmann). Or warm the tyrosin solution with the mercuric nitrate obtained by the precipitation of mercuric chloride with silver nitrate. 3. Heat with a drop or two of nitric acid (strong nitric acid and water, equal parts) on platinum foil or porcelain, and evaporate at a gentle heat : a shining yellow residue of brownish yellow crystals of nitrotyrosin nitrate, C9H,,(N02)NO.,.HN03, is obtained ; this becomes reddish yellow and then brownish on the addition of caustic potash, and leaves a brown residue on evapo- ration (Scherer). jNIany other bodies, such as sarkin, react similarly. Under Leucin it has already been stated that this body appears in patholofjical conditions in the liver, pus, sputum, &c., and in the urine in acute atrophy of the liver and phosphorus poisoning, &c. 141 BOOK II. DIGESTIOX AND THE SECRETIONS CONCERXED. CHAPTER I. FERMEXTS; FERMENTATION; AND DECOMPOSITION, OR PUTREFACTION. Before considering the subject of digestion in detail the opportunity may be here taken of referring to fermentation, which has so much to do with some of the digestive processes. And at the same time, to render the matter more complete, brief reference will be made to an allied process, that of decomposition, in which certain oi-ganic ferments play such an active part. FERMENTS. — The action of these bodies was compared by LiEBiG to that of platinum black in determining the union of a mixture of hydrogen and oxygen. In both fermentation and putrefaction a new arrangement of the elements occurs, gene- rally associated with an assimilation of the components of water, and resulting in the formation of new products. In j^utrefac- tion ofifensive odours are evolved, which is not the case with fer- mentation ; and while neither process can be regarded as one simply of oxidation, the loresence of oxygen appears to he necessai"y to set up the change. All fermentation processes require also the jjresence of water, and a proper degree of dilution appears to be more or less essential. A free acid, and that in a very dilute form, seems to' be needed in only a few cases, as in gastric digestion, while in most other fermentation processes an acid is in the way, if not positively hurtful. The caustic alkalies also, if above a very 142 DIGESTIOX ASD THE SECRETIONS CONCERNED. minute proportion, binder fermentation processes completely^ and the same may likewise be said of tbe salts of tbe beavy metals, as iron, lead, mercury, &c., if present in sufficient quantity, wbile some fermentations are prevented by tbe pre- sence of etber, cbloroform, &c. Ferments such as pepsin and trypsin, wben dried, may be heated up to 170° without their properties being impaired, but in the moist state a temperature of 100° is sufficient to destroy them (Huppe). Pasteur distinguishes two kinds of fermentation, one in which the ferment does not require the presence of oxygen (as the butyric) and one in which oxygen is essential in promoting the process. Ferments may be divided into the organised and the solu- ble. While the Hving organised ferments, such as yeast, re- produce themselves dm-ing their period of activity, the soluble ferments, such as ptyalin, pepsin, &c., do not do so. All fer- mentation produced by an organised ferment is arrested by hydrogen dioxide and the ferment is killed ; but the soluble ferments are not acted on by it (Bert and Eegnard). Borax, on the other hand, destroys the activity of all soluble ferments so decidedly that it serves as a test between the soluble and the organised class (Dumas and Schutzexberger). As a general rule it may be said that all purely jjhysiological fermentations in the organism are brought about by the soluble ferments, while pathological fermentations, on the other hand, are due to the organised series CEwald). In classifying these fermentation processes Hoppe Seyler's arrangement will be adopted. I. Change of Anhydrides into Hydrates. A. Ferments that act like Dilute Mineral Acids at a High Temperature. 1 . The conversion of starch into sugar, or glycogen into dextrin and grape sugar — 4(C6H,o05) + 3H20=C6H,oO., + 3(CV,H,206). glycogen dextrin grape sugar 2. The conversion of cane into grape sugar — C,2H220H+H20 = C,iH,A + C6H,20r,. grape sugar sugar of fruit FERMENTATION AND IJECOM POSITION. 143 3. The conversion of different benzol glucosides into sugar and simple benzol derivatives by the action of emiilsin — C,3H„0, + H.,0=C,H,206 + CeH,CH.(OH)2. salicin saligenin B. Ferments that act like Caustic Alkalies at a High Tempera- ture — Ferm enta t ive Saponification . 1. Splitting up of fats into glycerin and fatty acids. The process is favoured by the pj-esence of carbonate of lime and of neutral or alkaline solutions. The pancreas contains such a ferment, but it is so readily destroyed that it cannot be separated. A similar ferment also seems to be present in many decomposing substances. 2. Splitting up of amido-compounds by hydration through decom- position ferments f as — CON2H, + 2H20=(NH,)2C03 iirea amnionic carbonate C9H9NO3 H-HoO=C2H5N02 + C'^HgOa hijipuric acid gl3'cin benzoic acid C2oH45NS07 + H20=C2H7NS03 + C24H4oO,,. taurocholic acid taarin cliolic acid Possibly the decompositions of albumin effected by trypsin or putrefaction belong to this category. II. Fermentation Processes with Transference of Oxygen from the Hydrogen to the Carbon Atoms. 1. Lactic Acid Fe)- mentation. — Various kinds of sugar and dextrin, under the action of special ferments, as ])enicillum glaucum or bacterium lactis (Lister), are converted into lactic acid. A decom- posing albuminous substance, especially casein, water, and a tempera- ture between 30° and 35^ are required ; the presence of chalk or alkaline cai-bonates favours the process by neutralising the acid as it is formed, which would otherwise prevent the continuance of the fermentation. In the first stage lactic acid is produced — CgH, 206=20311503 C,2H220,,+H20 = 4C3H,303— and in the second stage butyric acid, carbonic anhydride and hydrogen l)eing evolved — 2(C3He03)=C,H802 + 2CO2 + 2H2. These processes, particularly the first, probably occur in the in- testine. 2. Alcoholic or Vinous Fermentation. — In this alcohol and car- 144 DIGESTION AXI) THE SECEETIONS COXCEHNEB. bonic acid are formed by the conversion of sugar in piosence of certain minute living organisms, as fornla cerevisia>, the fermentation beins; a correlative phenomenon of a vital act, beginning and ending with it, an organisation, development, and multiplication of the fer- ment particles occurring simultaneously "with the fermentation. CH2OH C0(0H)2 carbonic acid 2(CH.0H) o-^'^^^^^^^Ulcohol COH C0(0H)2 grape sugar In acetous fermentation the alcohol is converted into acetic acid under the influence of the mijcoderma aceti, Avhich acts as a sort of oxygen-carrier. • What is called mucous fermentation may be undergone by sugar when in presence of certain nitrogenous substances, hydrogen and carbonic anhydride being evolved, and mannite, lactic acid, ) A rtijlcial Saliva may readily be prepared by digest- ing witli water the finely mixed fresh salivary glands of any of the herbivora for several hours, and then straining through linen and filtcriiiff. 2. Artificial Gastric Juice. — (a) Open the stomach of a re- cently killed pig, or the fourth stomach of a calf, wash it rapidly in cold water, spread it out on a board with the mucous surface upwards, anfl scrape off this surface with a scaljjcl or sharp Pit E PA n A no X. OF THE JUICES. 156 spatula. Kul) \\\) the soft mass tluis obtained with some fine waslied sand; then digest the whole with cold water, stirring frequently, and filter. The juice prepared in this way contains very little peptones, which, however, would not be the case if some time is allowed to elapse after the death of the animal before the stomach is used. (6) Eapidly wash a fresh pig's stomach, mince the mucous membrane of its middle third, and digest this some six to eight liovu-s with 200 times its volume of dilute h^^drochloric acid (-)^ per cent.) at a temperature of 35°; decant and filter. The digestion may be repeated with fresh acid. Peptones will be present, which ma}^ be separated by dialj'sis. To 'prepare the hydrochloric acid of the above strength (4- per cent.) add about 6i c.c. of the ordinary strong commercial acid to a litre of distilled water and shake together. In the experi- ments the acid maybe used of this strength, or diluted with its own volume of water. An acid, however, tliat serves well for rapid artificial digestion contains one per cent, by volume of con- centrated hydrochloric acid (TusoN). The water in which the albumin is immersed may be acidulated with one per cent, of hydrochloric acid of sp. gr. 1*150 (=0'303 per cent, real acid) (Dowdeswell). or with only half this amount, and contain about 0*15 per cent, of real acid (Petit), so as to obtain rapid artificial digestion. (c) Divide the washed and detached mucous membrane of a fresh stomach into small fragments, and after drying them well between folds of filter jjaper cover them with strong glyce- rin ; lay aside for eight days, then strain the glycerin extract and precipitate it with alcohol ; collect the precipitate and wash it with spirit. It is then to be added to two litres or so of the acidulated water (0-1 per cent.), or a little of it may be added when required to the dilute acid (after Wittich). The glycerin extract may be filtered through linen, and kept as such, a very good digestive fluid being obtained by ad- ding a few drops of it to some of the dilute acid (1 per cent.) 3. Artificial Pancreatic Juice. — In preparing this juice it is advisable to employ the pancreas of an animal that has been killed some four or five hours after a fidl meed leas been taken; for if the pancreas of a fasting animal is employed scarcely any ]5G DIGESTION AND THE SECRETIONS CONCERNED. digestive power may be manifested by its glycerin or watery extract. (ct) Cut a fresh pancreas (say of a dog killed some hours after a full meal) into pieces, weigh them, and cover the pieces with absolute alcohol for two or three days; express through linen, and dry the gland substance with filter paper ; then rub it up with powdered glass or washed sand, adding for each gram of gland substance 1 c.c. dilute acetic acid (one per cent.) ; stir well for about a quarter of an hour, and then place the whole in a jar, pouriug over it ten times its volume of glycerin. After three days decant, and filter through a piece of muslin and then through coarse filter paper. (6) Make an infusion of the minced pancreas in warm water and neutralise the filtrate, if necessary, with sodic carbonate. (c) ^lince the pancreas upon a block of filter paper, and cover the fragments with strong glycerin ; filter in two or three days. 4. Artificial Intestinal Juice. — {a) Kill a dog or rabbit, and rapidly remove the small intestine. Attach the lower end to a tap, and clip the other extremity. Fill the intestine with water two or three times, emptying it after each addition, so as to clear it of its contents. As short a time as possible should be lost in doing this. Now slit the intestine from end to end, and scraping away the mucous membrane, rub it up with some sand, just as in the preparation of artificial gastric juice, and then digest it wdth four times its volume of water. Filter through muslin and filter j)aper in succession after it has stood for an hour or so. (6) The. natural juice is best obtained after the method in- troduced by Thiry, which consists in starving a sheep dog for twenty-four hours, then opening its abdominal cavity and draw- ing out a loop of the small intestine, which is to be cut at each end without disturbing its other connections, the continuity of the intestinal canal being re-established by connecting the open ends of the tube after the removal of the loop. The loop is closed at its lower extremity and left in the abdomen, and from its upper open end, which is fixed in the abdominal wound, the juice secreted is collected. '). Bile. — Fresh ox bile should be used, or some filtered IniirKin bih- obtained fi-oni the j)Osi.-m.ortP7n room. 157 CHAPTER IV. THE DIGESTIVE FERMEN-fS. As we have already seen, ferments may be living and organised, as is the case with torula, &c., or inorganised, as with the en- zymes, soluble ferments or zymases that occm* in saliva, gastric juice, &c. A body allied to these animal ferments is diastase, a peculiar nitrogenous substance, resembling vegetable albu- min, although not albuminous, which is found in germinat- ing seeds, being derived probably from the gluten, and possess- ing the power of converting starch into dextrin and glucose. The following compositions have been assigned to some of these bodies, although it is difficult, if not impossible, to obtain them in a state of purity : — C H N s Ash Emulsin (of almonds) 48-7 713 14-16 1-25 28-70 Schmidt Diastase (from beer of yeast) 49-6 6-5 11-8 — — — SCHLOSSBERGEU Pepsiit, 530 6-7 17-8 — — 22-5 Schmidt Do. 510 7-2 15-4 — — — Chapoteaux Ptijali 11 {^lycexm ex- tract) . 431 7-73 11-86 — 61 — HtJFXER Trypsin (glj'cerin ex- Do. tract) . 43-6 6-5 13-8 0-88 7-04 — Trypsin (without ash) 46-57 7-17 14-95 0-95 — 30-36 Do. Schmidt's pepsin is not probably pepsin at all, but rather an albumin peptone holding pepsin ; thus an albumin peptone has this composition: C = 53-5, H = 7, N=15-o, = 22*4, S=l-6. Although these ferments are probably formed at the expense of albuminous bodies, they have neither their composition nor general properties ; as compared with albumins they contain less carbon, but more oxygen, while the nitrogen, according to some observers, is much less. The ash of all these bodies is rich in phosphates. These ferments dissolve in water and glycerin, their solu- tions dialysing, but they are insoluble in alcohol. A tempera- 158 DIGESTION AND THE SECRETIONS CONCERNED. ture from 80° to 90° renders them inactive. One part of the salivary diastase or ptyalin is said to be sufficient to convert 2,000 parts of starch into sugar ; and while some authori- ties regard the amount of peptones formed by pepsin in an acid solution as indefinite, provided the peptones are removed by dialysis as they are produced and fresh acid added (Bkucke), others regard the action as limited (Schiff). I. To Show the Action of Diastase. — This body is first pre- pared by washing beer yeast with a mixture of water and ether, shaking well, and filtering ; precipitating the filtrate with alco- hol, and collecting and drying the precipitate. A little of this or of a warm water infusion of malt or germinated barley is added to a large quantity of thick gelatinous starch, and the temperature maintained at about 71° for a few minutes, when complete liquefaction of the starch will occur, and dextrin and glucose will replace it. Ferments exist in many of the tissues and organs, and to all mucous membranes there seems to belong a common fer- ment, enzym or zymase, capable of imparting its own mobility of molecule to many other organic bodies. Now the ferment in any organs or liquids can be obtained by exposing them thoroughly to the action of absolute alcohol for a week or two, so as to coagulate their albumin, and then exhausting the hardened tissue or precipitate with glycerin, from which the ferment can be afterwards thrown down by alcohol after Wittig's process. II. Preparation of Ptyalin. — 1. JNIince up the fresh saHvary glands of a cow, and make a watery infusion, and to this (or to saliva itself) add excess of dilute phosphoric acid ; then neutralise the filtrate with lime water or milk of lime, and the ferment will be precipitated along with the acid, albumin being thrown down at the same time, but it adheres more closely to the lime than does the ptyalin. Collect the precipitate on a filter, and wash it with a little water, which dissolves out the ptyalin, and this in turn is separated from the water by the addition of five to six times its volume of alcohol. Dry the flocculent precipi- tate in vacuo. By dissolving it up again, reprecipitating with alcohol, and drying it ia vacuo, as before, it is obtained in a purer form (after Coiinheim). THE DIGESTIVE FEIiMENTS. 169 The ferment may also be obtained by shaking up the watery infusion with a saturated ethereal solution of cholesterin or collodion. 2. Kapidly mince the perfectly fresh salivary glands of an ox, sheep, or rabbit, and cover with absolute alcohol for several days in a flask ; then collect in a linen filter, express the spirit thoroughly (or, if necessary, the alcohol may be distilled off at a low temperature), and expose the gland substance to the air to dry. Transfer the dried mass to a mortar, where it is to be rubbed up into a fine powder and then mixed well with glycerin ; now pour all into a flask, and cover with fresh gly- cerin, shaking occasionally. The glycerin extract is to be strained off and filtered after two or three days. From this the ptyalin is precipitated by alcohol, separated by decantation, and dried in an exhausted receiver over sulphuric acid. Properties. — Ptyalin forms a white amorphous powder ; its solutions in water are precipitated by neutral and basic lead acetate, but not by nitric or tannic acids or by mercuric or platinic chlorides. It has the power of converting starch into sugar, the most favourable temperature being about 35° to 40°, above G0° becoming inactive ; diastase, on the other hand, is most active between 60° and 70°. III. Preparation of Pepsin. — 1. (After Bhucke's method, which, however, does not furnish much pepsin.) (a) Macerate the washed and finely divided mucous mem- brane of the cardiac end of the fresh stomach of a pig in dilute phosphoric acid (5 per cent.), adding fresh acid until the solu- tion is nearly completed; filter, precipitate the filtrate with excess of clear lime water, collect the gelatinous precipitate of tribasic phosphate of lime and pepsin on a linen filter in which it is to be thoroughly expressed ; then digest it with glycerin, which extracts the pepsin. (6) Or the precipitate may be dissoh^ed in dilute hydro- chloric acid (about 2 per cent.), precipitated afresh with lime water to separate albumins, and to the filtrate a cold saturated solution of cholesterin in a mixture of ether (1) and alcohol (4) added ; shake well together, when the precipitated cholesterin will rise to the sm-face, carrying the pepsin with it. Collect on a filter, and wash with water, dilute acetic acid, and again IGO DIGESTION AND THE SECRETIONS CONCERNED. with distilled water till no precipitate is given with silver nitrate. Then digest the residue with ether so long as the ethereal extract leaves a residue on evaporation. Dry what remains at a low temperature, and a greyish white substance is obtained. (c) The precipitated phosphate of lime and pepsin may be dissolved as in h in dilute hydrochloric acid (2 per cent.), again precipitated with lime water, expressed as before, and more of the dilute phosphoric acid added, a little at a time and at long intervals ; wash the precipitate repeatedly with distilled water and dilute phosphoric acid. The pepsin is now present in a moderately pure condition, and may be separated with glycerin as in a or h. 2. Glycerin Extract. — Cover the dried and finely minced mucous membrane with absolute alcohol, and after 24 hours throw it upon some muslin and express out the spirit ; then transfer the mass to a beaker or flask and cover it with glycerin. Filter through muslin after some days, and then through filter paper, and precipitate the pepsin from the filtrate by the addi- tion of an excess of absolute alcohol. Collect the precipitate and dry it as before (after Wittig). The glycerin solution contains comparatively few foreign bodies. Glycerin is slow in dissolving up the pepsin, but- the addition of a very little acid greatly facilitates the solu- tion ; and the mucous membrane in the neighbourhood of the pylorus yields up its pepsin more readily if it has been previously treated with sodic chloride solution (Grutzmer). Properties. — Pepsin is a yellowish or greyish white powder, soluble in water and glycerin, but insoluble in alcohol. A watery solution does not diffuse ; it gives none of the albumin reactions, nor any precipitate with silver nitrate, but it is pre- cipitated by the neutral and basic acetate of lead. In the dry state it may be heated up to 110° without losing its properties, but this is not the case with its solutions. Without the addition of some dilute acid like hydro- chloric, phosphoric, or lactic it manifests no specific action. It is without action upon keratin, nuclein, starches, or fats. About 37° to 38° is the temperature most fiivourable to its activity. The presence of O'l per cent, sodic chloride aids the THE DIGESTIVE FERMENTS. IGI catalytic action of the pepsin, but 0*5 to 1 per cent, of this salt interferes materially with the process, while a saturated solu- tion throws down the pepsin from its solutions. An admixtuie of bile is likewise detrimental, as also an excess of alcohol. While the presence of arsenic does not interfere with the action of pepsin, that of carbolic acid does so materially. IV. Preparation of Pancreatic Ferments. — 1. Some of these may be separated in the same way as ptyalin (II., 1 or 2), using the fresh minced pancreas instead of the salivary glands. The ferment thus obtained acts very energetically ujwn starch between 37° and 4:0°. It converts glycogen at 12° into sugar. The presence of carbonate of soda is unfavourable to this starch conversion, and a temperature above 70° stops the change, although the dry powder may be heated to 100° without sustain- ing injury. 2. Kill a dog six hours or so after a full meal, wash out the pancreas through its vessels with iced water, then cut the pan- creas up small and rub the pieces in a mortar with clean sand ; macerate the product for two hours with 4 or 5 times its volume of water at 25° to 30°. (rt) Filter the decanted liquor through linen, add calcined magnesia in excess to the filtrate, filter again into a large flask, and drop slowly into the filtrate one-third its volume of thick collodion; shake vigorously, and having poured the mixture into a wide beaker, leave it to evaporate at a gentle heat, stirring con- stantly with a glass rod until the ether has escaped. When the jirecipitate presents a finely granular appearance, separate it by filtration through linen or muslin, and treat it as follows, reserving the filtrate for the separation of the diastatic ferment : wash the precipitate with alcohol, and extract it with a mixture of alcohol and ether ; the undissolved residue is then deprived of any alcohol and ether present in it by evaporation, when it is treated with water and the peptone ferment dissolved up, form- ing a yellow solution, from which the ferment can be precipi- tated by alcohol. The ferment thus obtained plays a part more or less like pepsin, acting better, however, in the presence of an alkali than of an acid. It forms a yellowish white amorphous powder insoluble in alcohol, but easily soluble in water or glycerin. M 102 DIGESTION AXD THE SECEETIOXS COXCEHyED. (b) The filtrates from the collodion precipitates are rapidly evaporated to one-sixth their combined volume under an ex- hausted receiver, absolute alcohol added, and the whole laid aside for a couple of days ; the precipitate thus formed is first washed with strong spirit and then with a mixture of 2 parts alcohol and 1 part water. Filter again, evaporate in vacuo, and dialyse the concentrated liquor ; to the contents of the dialyser further con- centrated in vacuo absolute alcohol is finally added to precipi- tate the diastatic ferment (after Damlewski). HuFXER, by macerating in glycerin a pancreas whose frag- ments had lain several days in alcohol, obtained an amorphous ferment having all the properties of pancreatic juice, and acting on starch, fats, and albumins. WiTTiCH extracts in a similar way by mincing the pancreas of an ox, leaving it twenty-four hours in alcohol, and then digesting with glycerin. The filtered extract is precipitated with alcohol. With regard to the properties and characters of these pan- creatic ferments and their origin, &c., see under Pancreatic Juice. V. Preparation of Liver Ferment. — There are probably two ferments in the liver, a diastatic or sugar-forming ferment and a butyric acid ferment (Pribram). The diastatic ferment is thus prepared : Cut the fresh liver into pieces, and dry them with blotting-paper ; then break them up into a fine pulp, add- ing a few drops of phenol, and having spread the pulji out in a thin layer on a piece of porous porcelain, dry it at 30°. The dried and pulverised mass is subsequently macerated for three days in glycerin. The glycerin extract is next precipitated with alcohol, and the precipitate redissolved in glycerin. Sodium chloride and sulphate in 5 per cent, solutions do not affect its action ; but the alkalies retard it, while the acids hinder or retard it according to the amount present. Ferments have also been obtained from muscle, one analo- gous to ptyalin (PiOTROV sky) and anotlier apparently identical with pepsin (Brijcke) ; and possibly also a third ferment is present, which causes the post- onortem formation of sarcolactic acid. 10:} CHAPTEK V. DIGESTION METHODS A.\l) EXPEL'IME.yTS. I. Conversion of Starch into Sugar. A. By Saliva. — As saliva converts starch into sugar it is advisable for the student first to perform the tests for starch and sugar on pp. 47, 63, and 64. 1 . Prepare some sta.rch tmicilage by rubbing a little starch into a thin paste with two or three c.c. cold water, and pouring it into 400 c.c. boiling water ; then boil for five to ten minutes," and when cool decant the clear liquid. 2. Conversion of Starch into Sugo.r by Action of Saliva. — ■ (rt) Add a little of the diluted saliva to some starch muci- hige contained in a small beaker, and lay it aside for ten mi- nutes or so in a hot chamber about 35° to 40°. It will also serve fairly well to place the beaker some time in water about 40°, or to gently warm it in a test tube over a flame, taking care, by bringing the test tube from time to time in contact with the palm of the hand, that the temperature does not rise much above 35". (6) Now apply the tests for starch and sugar, and it will be seen that sugar has been formed, and that the starch has dis- appeared in whole or in part. (c) Injiiience of Temperature, &c. — The same process should be repeated as in (a), with fresh portions of starch muci- lage and saliva, but vjith the conditions altered : thus, if a por- tion is boiled, the action of the salivary ferment is destroyed and no sugar is formed; if the action is allowed to go on at a low temperature, it will be greatly retarded ; and if at 0° C. it will be entirely arrested for the time being. Note also that with raw starch, say that of the potato, the conversion is very slow indeed. {d) Infuence of the Presence of Acids or Alkalies on the Pro- cess. — (j) Add variable amounts of hydrochloric acid to a mixture of starch mucilage and saliva, trying first a 4- per cent, and then a 10 per cent, solution, and it will be found that while the dilute solution apparently retards the process the stronger solution completely stops it. 1G4 niGESTlOX AND THE SECRETIONS CONCERNED. It therefore follows that the normal acidity of the stomach, which is about that of the -^ per cent, solution, does not entirely prevent the saliva swallowed from continuing to act on the starch present (Schiff). (ij) Note the retarding effect produced by the presence of even a small percentage of caustic soda or potash. B. By Pancreatic Juice. — Add a little glycerin extract of pancreas to some of the starch mucilage, and proceed exactly as in A, 2, and it will be found that the results are the same. C. By Intestinal Juice. — Add a little to some starch muci- lage, warm gently, and test as before for sugar. This juice further changes cane into grape sugar. Mix a little of the cane sugar solution with some of the juice, and lay aside for twenty minutes or so in a warm chamber (about 40°.) Test before and after with Fehling's solution : the cane sugar has little reducing power, but after the action of the juice it re- duces the copper rapidly, with the formation of the red or yellowish precipitate of cuprous oxide. The result, then, of the action of these juices on starch is to convert it into grape sugar— /rom the state of a colloid, in short, into that of a crystalloid. Note this by placing starch mucilage in one dialyser and solution of sugar in a second, and examine the fluids in which the dialysers float after twenty-four hours, when traces of sugar will be detected, but none of starch. It may here be mentioned that according to some recent researches (Wortmann) bacteria possess the power, under certain conditions, of acting on starch in. a manner analogous to diastase, a ferment appear- ing to be secreted by them which, like diastase, is soluble in water and piecipitable by alcohol, capable also of acting on the starch in the absence of oxygen, slightly acid solutions expediting the process. II. Conversion of Albumins into Peptones. A. By Gastric Juice. 1. Formation of Peptones. — Provide fragments of the following : washed fibrin that has been boiled, boiled or roast meat, wliite of boiled cg^ ; also some fresh milk. Place them separately in small flasks and cover tliem with artificial gastric juice ; then loosely cork them and lay them aside in DIGESTION METHODS AND EXPERIMENTS. IflS a warm chamber at a uniform temperature of 38° to 40° for several hours, and examine them from time to time, shaking them also frequently. A sHght increase of the temperature up to 50° promotes the digestion, but the process is materially retarded by the temperature being lowered even a few degrees below 38° or raised above 50°. (a) On examination it will bo observed that the solids have swollen up, and have lost somewhat of their opacity, while the milk has undergone coagulation from the precipitation of the casein. Later the solids fall asunder and are digested com- pletely. (6) A few c.c. of the clear fluid are to be removed with a pipette from each of the small flasks every fifteen to twenty minutes for the first hour, and again after two hours from their first having been placed in the hot chamber. This fluid is to be boiled, when it will be seen that coagulation occurs readily with the specimens removed at first, but that later the amount of coagulum becomes less and less, until at last no 'permanent cloudiness or indication of a precipitate occurs, although be- fore this is found many hours must have elapsed. At this point remove a fresh quantity from the flask, and neutralise it care- fully, when a precipitation takes place. That is, the albumin has been changed into a body which does not coagulate on boil- ing, and vjhich is thruivn down by neutralisation. This is acid albumin, or, as it has also been termed, farapjeptone, syntonin or albumose. (c) Examine specimens at a still later period, say after the lapse of four or even ten hours. (But if the peptones are re- quired earlier, or in larger quantity, digest a considerable amount of the proteid with the juice, and after a couple of hours decant and filter through coarse filter paper ; neutralise the filtrate accurately, and if any precipitate of acid albumin occurs, filter it off, and the peptones will be obtained in this second filtrate.) (1) Boil — no precipitate. (2) Neutralise — no pi'ecipitate. Acid albumin is therefore no longer present, but a new body, peptone. Apply to the solution the different tests given under Albu- VI in, noting: that — 100 DIGESTIOX AND THE SECRETIOXS COXCERNEI). (1) It gives the pi'otein i-e;ictions~I\Hlloii's, tlie xanthoproteic, aiid a purple red coloration with excess of Feliling's solution. (2) It dialyses. (3) It is precipitated by alcohol, and by strong solutions of mer- curous and mercuiic nitrate and mercuric chloride, plumbic ammonio- subacetate, and tannic acid. (4) It is not precipitated by acids or alkalies, acetic acid and potassic ferrocyanide, nor by cupric sulphate or earthy salts. 2. Influence of Excess of Acid, Temperature, &c. — Place fragments of the boiled fibrin in three additional flasks, and add to these respectively (1) 10 c.c. dilute hydrochloric acid (4- per cent.), (2) 10 c.c. artificial gastric juice that has been boiled, and (3) 10 c.c. of the same juice that has been exactly neutralised. These flasks, when labelled, are to be placed in the hot chamber (at 40°) and occasionally examined. (4) A small flask containing fibrin and artificial gastric juice is to be placed in an ice chainher ; and (5) three other flasks with the same contents as in (4), but with the fragment of fibrin in the first firmly iurapp)ed round luith silk thread, and with the addition of some strong solution of sodic chloride to the second, and some drops of strong hydrochloric acid to the third, are also to be placed in the hot chamber (40°). Ifoie : with (1) that no peptone has been formed, acid albumin only being present, which is shown by its precipitation when the fluid is neutralised. Acid alone is therefore incapable, or nearly so (WiTTicn), of forming peptone. With (2) the same result as with (1), the action of the pepsin having been destroyed by the boiling, and the acid alone acting. With (3) the fibrin remains unaltered, the pepsin not acting on the fibrin in the absence of free acid ; but that the action is only suspended can be shown by adding more dilute hydro- chloric acid. With (4) it will be seen that the low temperature stops the action; while in (5) the digestive action is greatly retarded by the fibrin being prevented from swelling up by the mechanical pres- i^uTG and by the presence of excess of common salt and of acid. 3. To shovj the continuous ferment action of the pepsin, place some pieces of fibrin in a small dialyser, and having added a sufficiency of artificial gastric juice, suspend it in warm water inside a hot chamber (40°). If fresh, acid (^ per cent, hydrochloric acid, or better dilute phosphoric acid) is poured in occasionally, additional ])iccoR of filiriu may continue to be DIG EST I ox MET HODS AND EXPERIMEXTS. 107 .added without retarding the process, conversion into peptones continuing, which would not be the case if the peptones were allowed to accumulate, but as they dialyse out the action of the juice is not thereby hindered. For the gastric juice to act advantageously we thus see that it imist contain 'pepsin, and that it is necessary for the Uvipeo'ature to be kept about 40° C, for a normal acidity to be maintained, and for the pjeptones formed not to he alloived to accumulate. B. By Pancreatic Juice. 1. Proceed as in A, using glycerin extract of pancreas diluted with sodic carbonate solution (1 per cent.) instead of the artificial gastric juice, and fragments of boiled fibrin in prefer- ence to any of the other proteids. Peptones will be formed, as with the gastric juice, and it will be found that a temperature about 35°, a moderate degree of alkalinity instead of acidity, and a certain lapse of time are necessary for the conversion. The physical change in the pro- teids differs slightly from that effected by the artificial gastric juice, as is well seen in the case of the fibrin, where this body appears to be eaten away rather than rendered transparent and dissolved, as with the gastric juice. 2. Some of the peptone formed is afterwards decomjoosed into leucin and tyrosin, &c. Let the digestion go on for a day or two, then acidulate with acetic acid and boil, and if any precipitate occurs filter ; evaporate the filtrate at about G5°, and when considerably reduced in volume add to it, while yet hot, alcohol to precipitate the peptones ; filter after twenty- four hours, and having evaporated the filtrate to a small bulk, let it cool, when tyrosin crystallises out The mother liquor, when decanted and evaporated still further, yields crystals of leucin. Purify the tyrosin by washing it on a filter successively with ice-cold water, spirit, absolute alcohol, and ether ; and after allowing the crystals of leucin to drain completely on a filter, proceed exactly with their purification as with the tyrosin crystals. (o) Test the Leucin. — Note the appearance of the leucin, if pm^e, in the form of white and glistening, fatty-looking leaflets, and under the microscope often appearing in the form of little IGS DIGESTION AND THE SECRETIONS CONCERNED. glistening balls, occasionally radially striated. Add some crys- tals to a little cupric hydrate in a test tube, and an intense blue fluid will be obtained on boiling. Or, if the dry crystals are heated in a subliming tube, the leucin will sublime in woolly masses, part decomposing with the odour of methylamine. (6) Test the Tyrosin. — It occurs in bunches of felted, silky- looking Avhite needles, though occasionally in hard white balls. Dissolve a few crystals in hot water and boil two or three minutes with a few drops of Millon's reagent, and a rosy red to a dark red colour is obtained (Hoffmann). Or dissolve some crystals in strong sulphuric acid, and heat over a water bath for half an hour ; dilute it well with water and saturate with carbonate of baryta, filter, evaporate nearly to dryness, and filter again if necessary ; now treat the residue or the filtrate with very dilute ferric chloride solution, when a violet coloration is obtained (Piiua). (c) The ultimate mother liquor is then to be tested for naphthilaonine by diluting a few drops of it with water, and then slowly adding chlorine water, when a rose-red colour appears. {d) Boil a little more of the same diluted mother liquor in a test tube, then add a few drops of dilute sulphuric acid and of a dilute nitrite solution, and a recZ colour shows itself, in- dicating the presence of indol. Instead of the nitrite a solution may be employed of nitrous acid, readily obtained by filling a small flask with the red fumes of nitrous acid by boiling a little nitric acid with copper foil, then suddenly inverting the flask, and having thus discharged the foil and nitric acid, adding a little cold water and shaking for a few minutes. III. Digestion of Fats. A. By Pancreatic Juice. — Use afresh watery infusion, as a simple watery infusion, if kept, tends to become acid. 1 . It emulsifies. Eub a little olive oil or melted lard (of a temperature below 40°) with rather more than twice its volume of the simple watery alkaline infusion of pancreas in a small mortar that has been taken warm out of hot water. A creamy emulsion is formed, which remains as such for several hours. DIGESTION METHODS AND ENIEI^LMENTS. IfiO 2. It also sajjonifies, decomposing the fat and liberating the fatty acid and glycerin. Add a little of the watery infu- sion, that has been carefully neutralised, to a few drops of olive oil in a test tube. Shake well and expose to a gentle heat for a short time. Then, by means of a pipette, transfer a drop from the bottom of the test tube to a piece of blue litmus paper, and a red spot will be left when the drop is thrown off. B. By Bile. — 1. Rub some olive oil with an equal amount of fresh ox bile in a mortar, and then pour the mixture into a small flask, where it is to be well shaken for some minutes. An emulsion is formed, which remains permanent for a short time. 2. To shoio that fatty bodies more readily jpenetrate mem,- branes moistened with bile than with tuater, take two small filters, and after brushing one with water and the other with fresh bile or a watery solution of it, pour an equal quantity of oil into each filter, and leave aside for a few hours, taking care to keep the filters sufficiently moistened on their outer or lower surface with water and bile respectively. It will then be seen that some of the oil has passed through the filter moistened with bile, but none through that wetted with water. CHAPTER VI. CHEMISTRY OF THE DIGESTIVE SECRETIONS. The Saliva — This is the first secretion to whose action the food is exposed. It is the product of the combined secretion of the parotid, submaxillary, and sublingual glands. In the mouth these secretions are mixed together as well as with the mucus secreted in that cavity itself. The mixed saliva forms a clear or glairy, frothy, and generally turbid fluid without taste or smell, having a sp. gr. of 1002 to 1006, an alkaline reaction, and almost 0*5 per cent, of solids, of which 0*2 consists of salts, and the rest of ptj^alin, globulin, and serum albumin. It de- posits a sediment in which are epithelial cells from the mouth and salivary corpuscles — little bodies resembling the pale cor- puscles of the blood and probably derived therefrom. The al- kaline reaction seems to depend on the presence of bicarbonates 17U DIGESTION AND THE SECRETIONS CONCERNED, and phospliates of the alkalies, though the combination of the ptyalin witli soda may assist. Saliva from different individuals may show a constant difference in alkalinity, although it varies only within narrow limits ; and while showing within certain limits in the same individual a constant degree of alkalinity, there is a decided and constant difference in different indivi- duals, but no constant corresponding difference in diastatic action (Chittexdex). Chemical Composition. — The important bodies present in saliva are the diastatic ferment, ptyalin, mucin, and the chlorides of sodium and potassium ; in addition are found traces of albu- min, fat, potassic sulphocyanide, sulphates and phosphates of the alkalies and alkaline earths, and sometimes, even in normal saliva, urea and ammonic nitrite. Mixed /SrtZfm- Human (Jacubowitsch). Water 99-51 Solids . . . ■. 0-48 Soluble organic bodies (ptj'alin, &c.) . . 0-13 Epithelium 0-16 Inorganic salts ....... 0-182 Potassic sulphocyanide 0-006 Pota.'-sic and sodic chlorides .... 0-084 Mixed /SaZira— Human (Hammerbacher). Water 92-42 Solids 0-58 Epithelium and micin 0-22 Ptyalin and albumin ...... 0-14 Inorganic salts ....... 0-22 Potassic sulphocyanide 0-004 la 100 Parti; Soluh. Epithelium and mucin 37-98 Ptyalin and albumin ...... 2.S-97 Inorganic salts ....... 38-03 In 100 Pari a A all. Potash 4.0-71 Soda 9-59 Lime 5-01 Magnesia ........ 0*16 Phosphoric anhydride . * . • . • 18-85 Sulphuric „ ...... 6-38 Chlorine 1835 1-8 per cent, of the sul]»huric acid existed as such, tlie rest being derived from tlio organic matter. CHEMISTRY OF THE DIGESTIVE SECRETIOXS. 171 EvDKiitiiN gives in tlio 100 pai-ts of ash 92'37 furnish material 184 DIGESTION AND THE SECIiETlOlSS CONCERNED. for the secretion, and being leneAved at the expense of the outer zone, which in turn is maintained at the expense of the blood. The amount of the z}mogen rises and sinks with the granular inner zone (Heiden- hain). In a state of hunger this zone is the more conspicuous, the outer homogeneous zone being insignificant. In the early stage of diyestion, some hours after the taking of food, the cells undergo a decrease in size, owing to the consumption of the granular zone, the homogeneous zone, however, showing an increase. At a later stage the secretion sinks, and the granular zone becomes built up anew at the expense of the homogeneous outer zone, and this latter is reduced to a minimum. After long starvation the homogeneous zone is the more abundant, the inner zone being much reduced. Conditions Affecting the Digestive Phenomena. — The action of the pepsin on the albumin is dependent on the temjDerature and on the jjrojjortion of jjejpsin and of free acid, preseoit. The most suitable temperature seems to be about 37°, as above 50° the juice begins to lose its digestive properties and above 60° becomes inert; at 0° it also loses its activity, but it re- covers it again on being heated. It is probable that the diges- tion of fibrin begins quicker and continues more rapidly the greater the proportion of pepsin present. A proportion of 0*8 to 1 gram hydrochloric acid per litre makes a fairly digestive fluid ; but for cooked albumin a j)i'oportion of 0*17 per cent, acts most strongly, although Ebsteix and Gku^stek found 0*2 per cent, the most useful strength. Pepsin seems to act best when the acid present bears a definite relation to the albumin mole- cule with which it probably enters into combination. Accord- ingly the process of conversion uses up the free acid, while it does not appear directly to involve any destruction of the pep- sin. A very small quantity of pepsin may therefore effect the conversion of a very large amount of albumin. In some experiments of BRiiCKE's upon the rapidity of di- gestion in relation to the amount of pepsin and acid present, he found that when a 0*1 per cent, hydrochloric acid was used in the digestion of fibrin the conversion went on more rapidly with an increased proportion of pepsin : with x pepsin, for example, the digestion was completed in forty-five minutes, with 2x in twenty minutes, with 4,'>c in fifteen minutes, and with Sx in ten minutes. An increase in the percentage of the acid, on the other hand, rendered the digestion much slower, about one hour GASTBIC JUICE. 185 being added for every j'^ per cent, of acid above y^ per cent. But some definite relatiousliip seems to exist betweon the relative amounts of acid and pepsin in a good digestive liquid, for we find that dilute pepsin solutions act best with dilute acid solu- tions, while strong joepsin solutions require a greater proportion of acid. Fibrin is said to need a less degree of acidity for its digestion than white of egg. The quantity of water present also affects the process, much water retarding it. An accumulation of the pejrtonised albumin mechanically hinders its continuance; the presence of bile also interferes ; and so likewise is the case with acetate of lead and mercmic chloride, except in very moderate quantity, concen- trated solutions of sodic chloride and of the alkalies, dilute so- lutions of phenol, and alcohol in excess — they all interfere more or less with the digestive process in the stomach, chiefly by precipitating the pepsin or the peptones, or by causing a copious alkaline exudation. Beer does not appear to act detri- mentally (Bucheim) ; and spices, such as ginger, pepper, and cinnamon, appear to encourage the secretion of the juice. The jjTO'perties of the jjeptones have already been given (p. 121), also their modes of preparation (pp. 120, 164). To }mr[fy them, neutralise the acid liquor contaiiiing tliem with baric or calcic carbonate; then boil, concentrate over a water bath, and 61ter. To purify still further recourse may be had to dialysing the solution, but the process is very slow; instead we may separate excess of baryta by the careful addition of sulphuiic acid and subse- quent filtration ; or if lime has to be separated, first concentrate by evaporation and then precipitate with alcohol ; a little lime, however, remains combined with the peptone. The secretion of the gastric juice is essentially intermittent, and is excited by different stimuli. Different bodies introduced into the stomach cause the mucous membrane to become red and swell up, and subsequently to pour out its secretion ; the character of the stimuli is said to affect the character of the se- cretion, that excited by mechanical or chemical excitation being less rich in digestive principles (pepsin, &c.)than that secreted under the influence of the food ; the degree of acidity probably also varying with the nature of the physiological stimulus. This secretion is probably the result of a direct irritation of a ISQ DIGESTION AXD THE SECRETIONS CONCERNED. local ganglionic centre that is in connection with the central nervous system. Afferent impulses likewise pass up the vagus, and by inhilnting the vasomotor centre in the medulla bring about the dilatation of the vessels of the stomach, section of the vagi leading to a temporary anaemia of the mucous mem- brane (Rutherford). Pepsin is possibly formed more or less continuously in the glands, although it is not probably contained there in a free state, but rather as an albuminate combination that is easily split up and rendered active by hydrochloric acid or a chloride. The hydrocJiloric acid appears to be formed only as the result of reflex or direct stimuli ; but while in the fundus free acid is present, being secreted there, this does not seem to be the case in the pyloric end. A mucous membrane rich in pepsin also contains much sodic chloride (0*6 to 1*5 per cent.) In the formation of free hydrochloric acid a dissocia- tion process probably precedes in the chloride, 2Na2HP04 + 3CaCl= Ca32P04 + 4NaCl -f 2HC1 (Maly). Thudichum assumes that sodic chloride and lactate are split up in the walls of the stomach into free acid and caustic soda, NaCl + HgO = NaHO 4 HCl. This caustic soda, according to Thudichum, assists in protecting the mucous membrane of the stomach against the action of the gastric juice, and becoming converted into carbon- ate enters the blood and is carried to the liver ; but the conti- nuous circulation of alkaline blood through the mucous membrane of the stomach is no doubt one of the reasons why it is not di- gested (Pavy) ; the question, notwithstanding, cannot yet be regarded as solved. The pepsin is poured out abundantly on the taking of food, then falls in amount for the next hour or two, and rises again about the fourth or fifth hour (Geutzner). Its secretion appears to be favoured by the previous ingestion of dextrin and certain other pepsigenous materials (Schiff). Pathology. — The amount of pepsin, as well as of the wliole juice, appears to be much reduced in fevers and acute anaemia; in some of these cases, as well as occasionally in catarrh of the stomach, pepsin :ind hydrochloric acid may be both absent ; but we may find instead butyiic or lactic acids in gi-eater oi- less quantity. Sarcinse, bacteria, and different feimentation products may at GAfiTRlC JUICE. 187 time,s present themselves; also mucus in excess, and bile, and in hiematemesls blood, which last may be vomited iip unaltered, or, if it has lain some time in the stomach, in the form of dark coffee gi-ounds. The vomit may be alkaline and contain albumin, epithelium, and mucus, as in cholera ; or urea, carbonate of ammonia, etc., as in iirfemia, &c. Digestion is interfered with by the presence of Ijile or mucus, much free acid or alkali, much metallic salt, chlorides, sulphates, or nitrates, anhydrous salts hindering fermentation more than hydrovis salts ; the alkaloids also, except quinine, retard the process. As to gases in the stomach, normally little or none is present with the exception of the air that has been swallowed with the food or of a little that has diffused from the blood ; for the gases resulting from fermentation will not be met with unless some abnormal condition is set up, although it is possible for some of the gas occasionally found in the stomach to come up from the duodenum. Planer found gases having this composition : — CO., = 20 to 33 percent. H ■= 7 „ 27 „ N =38 „ 72 „ O = 0-4 „ and HoFMANN and Ewald : — CO., = 1-7 to 28 per cent. h'=20 „ 32 „ CH,= 0-2 „ 10 „ = 6 „ 11 „ C2H4 and N, trace.-;. Owing to the diminution in the hydrochloric acid in fevers, and to the tendency of the mucous membrane of the stomach to become catarrhal, decomposition processes are favoured, and the digestion greatly interfered with. In some of these cases the pepsin does not appear to be wanting, rather the acid to set it free and render it active. 188 DIGE^iTlOX AND THE HECltETlOXS CONCERNED. CHAPTER VIII. PANCREATIC JUICE. This is a clear, odourless, and very alkaline liquid ( = 0'3 per cent. Na^C03), having a salt taste and a sp. gravity of 1008 to 1010; it is ropy and viscid when first collected, but later it becomes thinner. It decomposes readily. When heated to 75° a slight coagulum appears, which likewise occurs on the addition of alcohol, mineral acids, tannic acid, metallic salts, magnesic sulphate, and chlorine water. Quantity. — From researches on dogs the amount secreted in the twenty-four hours has been estimated at 150 grams (5^ oz.) (Bidder and Scilmidt), or 140-7 grams (Ludwig and Wei^mann) ; but it is more probable that it amounts on an average to 10 to 11 oz. The Secretion. — Immediately after food is taken its secretion begins, reaching its maximum two hours later ; then occurs a fall, succeeded by a secondary rise some five or six hours after- wards, and a sinking again to zero in sixteen to eighteen hours, but rising again rapidly with fresh ingestion of food (Bernstein). The secretion appears to be most active five to seven hours after a meal. Nausea or vomiting and section of the vagus stop its secre- tion temporarily ; and it is increased by stimulation of the me- dulla oblongata, or by centripetal stimulation of the vagus. Its chemical constituents are water, albumin, mucin, fats, ferments, and salts, the last consisting chiefly of sodic and po- tassic chlorides, calcic phosphate, sodic carbonate, and traces of ferric phosphate. Fresh juice contains bodies similar to salivary corpuscles, and only traces of leucin, neither peptones nor tyrosin being present (KiJHNE). After the juice has stood some time tyrosin, fats, and a small amount of soaps may also make their appearance, the leucin and tyrosin being due probably to an intrinsic digestion of the albumin of the juice itself. A com- paratively large amount of soda is present, peculiarly associated with the albumin, and probably in the form of carbonate, to which the alkaline reaction of the juice is due. PANCREATIC JUICE. 189 Anahjsis of Pancreatic Jiticc — Doy (C. ScirMiDT). From a pcrnianeut ^'■°'" " ^''^^''^^ . fistula oijciied pancreatic 'luct Water 9808 90-07 Soluls 1-92 9-93 Organic substances, asalbmnin, alkali albumin l-2ij 9-04 Inorganic salts ...... O'GG 0'89 Soda combined with albumin, and traces of lime and magnesia similarly combined . 033 0"09 Sodium chloride 0-24 073 Potassium „ 0*08 0-02 Phosphates of lime, magnesia, and soda . 0-01 O'Oo The normal j^ancreatic juice contains, according to Bernard, from eight to ten per cent of solids, of wliicli about one per cent, consists of inorganic salts and the rest of organic matters : this corresponds with Schmidt's analysis of a normal juice obtained from a recent fistula. The juice coming away from a permanent fistula soon alters in chai'acter, and accordingly is not a correct representative of the normal secretion, being much thinner, and containing much carbonic acid, and only about one to two per cent, of solids; guanine (C.5H5N5O) has also been found in it. But Bernstein only obtained an average of 3*3 per cent, solids in an apparently perfectly normal juice, of which O'S per cent, was inorganic matter. The above estimates, it should be said, apply chiefly to the secretion in dogs. The pancreatic peptones are precipitated by acids and acid salts, except the acid pho,sphate of soda, and the filtered liquor is precipitated by tannic acid and acetate of lead (Diakonow), thus differing from gastric peptones. Ferments. — 1. A diastatic ferment, isolated by Cohnheim and WiTTicii, and probably identical in many respects with ptyalin ; it rapidly changes starches into sugars. 2. A pepjtone-forminy ferment, p)ancreatin or trypjsin. After long fasting this ferment is absent (Heiitzen). 3. A ferment luhich splits fats by hydration into fatty acids and glycerin. It has not yet been isolated. Zymogen. — According to Heidenhaix there is no preformed free ferment in the pancreas, but there is present in the gland a body he names zymogen, which builds up one or more of these ferments. From this zymogen, naturally after each act of stomach digestion, and artificially by treatment with acids, the ferments are obtained for the digestion of albumins, and probably 100 DIGESTIOy AXD TEE SECRETIONS COXCERXED. also for tliat of the starclies and fats. Tliese ferments are active in alkaline and neutral fluids ; a temperature above 50°, as also the addition of alcohol in excess, destroys or hinders their activity, although dry trypsin may be heated up to 110° without losinof its ferment power. Pepsin also appears to act deleteriously, rendering trypsin inactive, but this is not apparently the case with the zymogen. The varied action, then, of the pancreatic secretion depends on the presence of these three ferments. They are collectively more soluble in solutions of sodic chloride, alkaline sulphates, and potassic clilorate than in water. The albumin ferment is soluble in sodic hypo-sulphite, potassic arsenite, and tartaric acid ; the dmstatic ferment specially soluble in potassic arse- niate and tartaric acid; and the fat ferment in a mixture of bi- carbonate of soda with one-fourth its volume of caustic soda so- lution, or in antimoniate of potash. By means of these solvents a separation may be eflfected of the different ferments, dialysing at the same time through porous earthenware under reduced pressure (Paschuitn). The zymogen is soluble in water, where it is readily split up, after exposure for some time to the air, into trypsin, (*fec., but little or none of the ferments is dissolved out of the glaiid substance by glycerin, unless the z3Tiiogen has been previousl}^ decom- posed by the action of dilute acids or otherwise. The decom- position of the watery solution occurs more readily at an elevated temperature and under the action of acids, and it is more or less hindered by the presence of soda or its carbonate ; but the ferment, when once formed, is more active in presence of soda or sodic chloride than in a simple watery solution. The o/niount of zymogen in the gland depends on the con- dition of the digestion, being most abundant fourteen to twenty- four hours after food, although the juice richest in the albumin ferment is generally secreted six to nine hours after a meal ; and it is probable that a constant formation of zymogen is going on in the secreting cells, aod that at intervals, under the influence of certain stimuli, this zymogen is converted into the pancreatic ferments, which, as we have seen, are the products of the secre- tion of the inner zone of the secreting cells of the pancreas. The separation of the pancreatin from the fresh gland can PANCREATIC JUICE. 191 readily be effected by rubbing up the gland with 1 per cent, acetic acid, in the proportion of 1 gram gland substance to 1 c.c. acetic acid, and then digesting for several days with glycerin. A watery solution acts very slowly, but the presence of sodic chloride, or better still of soda, quickens its action. The more ferment is present the less soda is necessary ; but with a mo- derate amount of ferment a percentage of 0*9 to 1*2 of soda is most favourable. With 6 per cent, soda the action is much hindered. It acts properly only in neutral or weakly alkaline fluids, and without any previous swelling up of the fibrin or coa- gulation of the albumin immersed in it, such as occurs in gastric digestion. The cUastatlc ferment, while apparently identical with the ptyalin of saliva, appears to be more active in its properties. The fat ferment has not yet been isolated, but an active extract can be obtained by rubbing up some quite fresh pancreas with a mixture of glycerin (nine parts) and soda solution ( 1 per cent, one part) together with some clean sand, and allowing the whole to digest for four days. Acids destroy the action of this ferment. As to the activity of these ferments, it would appear that their action within certain limits is in inverse proportion, a double quantity doing a given amount of work in half the time ; further, that they liberate their energy at a progressively re- tarded rate (W. Roberts). It follows therefore from the above that the digestive actions of pancreatic juice may be classified under these heads : — 1. It changes starches rapidly into grape sugar, actino- more powerfully than saliva ; the transformation is very rapid at 35°, and the presence of bile or gastric juice does not retard its action. One gram of the juice of a dog. containing only 0*014 gram of organic solids, converted 4:'672 grams of starch into sugar and dextrin in half an hour at 35° (Kroger). Not till the second month after bhth is the infant's pancreatic juice able to digest starch, but at the age of a year its power in this respect is equal to that of the adult. 2. It dissolves coagulated albumins, acting best at 35° to 40°, changing them into peptones, appearing to act specially on muscle fibre and fibrin ; but its general action on albuminoids 192 DIGESTION AXI) THE SECRETIONS CONCERNED. is nearly teu times more energetic than that of gastric juice. Gelatins are also converted into peptones, and with prolonged digestion leucin and much glycocin may appear. By the action of alkaline solutions of pancreatin on albumins Danilewsky in some recent researches obtained several intermediate bodies, but the final product was always peptone. An albumin is first produced insoluble in water and warm alcohol, of weak acid reaction, and containing sulphur together with lime and phosphorus. The bodies next formed are more soluble in water and warm alcohol, more strongly acid, and free from lime and phosphorus. Finally come the peptones, which combine with bases and acids and yield no sulphides with alkalies. The undigested proteids issuing from the stomach are to be digested entirely or in great part by the pancreatic juice, and the presence of bile favours rather than hinders the process ; but to what stage the digestion is carried, and whether much of the peptones formed is broken down into leucin and tyrosin, &c., is unknown. Further and later decomposition products of these peptones may appear, such as aspartic and glutamic acids, and even xanthin and hypoxanthin (Radziejewsky, Salomon). YroTD. jjrolonged action of this juice outside the body, but more probably also as a result of decompositions occurring (Kuhne), certain other products may show themselves, such as indol, skatol, phenol, phenyl-sulphuric, phenyl-acetic, and ])lienyl-propionic acids. 3. It contributes very largely to the digestion of fats, emul- sifying and also saponifying them to a slight extent — the latter possibly, however, only so far as to facilitate the emulsifying of neutral fats. The emulsifying property is not entirely due to the alkalinity of the juice (Bernard), but is probably in great measure dependent on the alkali albumin ^^resent. In experiments ivith pancreatic juice great care should be taken that it is prepared from a fresh and unaltered gland; otherwise imperfect results will be obtained. As an example liow readily the character of the secretion is altered, it is stated that the removal of the spleen deprives the pancreas of peptone-forming power (Sciiiff). It is very difficult also to avoid decompositions occurring in experimenting with pancre- VANCREyiTIC JUICE. 193 atic extracts, bacteria soon making their appearance unless such a body as saHcylic acid is added. Difference hehueen Peptic and Tryptic Difjesiion. — Pancre- atic digestion, it should be noted, includes the action of the three ferments, tryptic being applied solely to the allmminoid conversions and changes. 1. Peptic digestion only occurs in an acid medium; in pancreatic the reaction is alkaline, and some alkali must be present for it to take place : the acidity of the gastric juice, re- presented by 0*2 jDer cent, hydrochloric acid, is in the pancrea- tic juice replaced by an alkalinity corresponding nearly to 1 per cent, sodic carbonate. 2. In tryptic digestion a globulin body resembling alkali instead of acid albumin is formed previous to the peptone stage. 3. A considerable amount of proteid in tryptic digestion is broken down beyond the peptone stage into leucin and tyrosin, the antipeptone residue, however, which forms about half the weight, resisting this decomj^osition. 4. While fibrin is readily acted on by both juices, boiled albumin and syntonin are more easily converted by the gastric than by the pancreatic secretion. 5. In the case of fibrin, with tryptic digestion, no previous swelling up occurs, as in gastric digestion, and it remains opaque, appearing to be corroded rather than dissolved. Indeed, in alkaline tryptic digestion albuminous bodies generally undergo no previous swelling up or coagulation, as is the case with peptic digestion. 6. Pancreatic juice does not appear to have any direct solv- ent action on the gelatiniferous elements of the tissues, imless these have previously been boiled or treated with acids. 7. Trypsin dissolves mucin, which is unacted on by pepsin. 8. Decomposition sets in readily during pancreatic, but very slowly during gastric digestion. 9. In gastric digestion the rotatory power of the transformed matter is but little lessened, remains unchanged, or is increased, whilst in pancreatic digestion it is always enormously lowered (Bechamp). o 104 l)lGi:STIOX AXIJ THE SECRETIONS CONCERNED. Pathology. — In certain diseases of the pancreas, such as chronic inflammation, degeneration, and cancer, a great excess of fatty matters appears in the evacuations. Pancreatic calculi are occasionally, but rarely, met with ; they are like salivary calculi, and consist chiefly of phosphate of lime (60 to 80 per cent.), a little carbonate of lime (10 to 20 per cent.), and animal matter (7 to 16 per cent.) CHAPTER IX. INTESTINAL JUICE. This juice is a clear, opalescent, greenish yellow, and strongly alkaline viscid secretion, having a sp. gravity of 1011 (Thiry), and containing about 2*27 to 2*4 per cent, of solids, of which more than one-third consists of inorganic salts, one-third albumin, and less than one-third of the other organic bodies. It effervesces with acids, yields no mucin, and is coagulated by alkaline chlorides and sulphates in excess. It appears only to be periodically secreted, and is a mixture of the secretions of Brunner's glands and Lieberkiihn's crypts. Comparatively little is known as to its exact composition and properties, some even regarding the fluid obtained by Thiry's process as more or less of a transudation. Quantity. — From the amount secreted by a small piece of the intestine of a dog, Thiry calculated that the whole small intestine secreted, from the second to the fifth hour after a meal, 360 grams (12| oz.) of intestinal juice. Bidder and Schmidt's estimate was 300 c.c, or 10? oz. Do ?(TiimY) Horso (Cor,iN; Water .... 97-58 98-10 Solids .... 2-41 1-80 Albumins .... Other organic cnnstidienls 1^80 0-73 ]'0-45 Inorganic salts . 0-88 — Carbonate of soda vol 17+ 1/1 c!ar.v/:>+ir>n lin« TPPl 0-32 nlif Mint 1-45 yellowish, strongly alkaline, sp. gravity 1008, poorer in solids INTESTINAL JUICE. lOo than the normal juice, and containing only about a cjiiarter as much organic, but nearly the same amount of inorganic con- stituents ; it also contains about 0"016 per cent. urea. Actions. — It is probable that some of t lie diversity of opinion as to the action of this juice is due to a difference in the cha- racter of the secretion in different animals. Thus the intestinal juice of dogs, pigs, and rabbits converts cane into grape sugar, but this is not so with the juice of ruminants, &c. 1. It probably contains a diastatic ferment, soluble in sodic nitrate and potassic and sodic bicarbonate, capable of readily converting starch into sugar fCoLiN, Schiff), although this is denied by Thiry. But a glycerin extract of the wliole mucous membrane of the small intestine undoubtedly contains a dias- tatic ferment capable of converting starch into sugar. 2. It contains a ferment soluble in potassic chlorate, which converts cane into grape sugar, transforming some of the latter into lactic and butyric acids (Frerichs ) ; but a little of the cane sugar remains unchanged (Hoppe Seyler). .3. Its action on fats is doubtful, probably negative (Thiry). It may, however, exert a slight emulsifying action (Schiff). 4. It appears that fibrin is rapidly dissolved by it (Thiry, KiiHNE), and probably also a little casein and albumin (Schiff). The fibrin does not swell up, but crumbles to pieces. Ac- companying this peptonisation, if not the cause of it, there seems to be a certain amount of decomposition of the proteid. 5. Cellulose, gums, &c., are not necessarily modified. Further, in the intestinal digestion certain ferments play a part by producing diastases that superimpose their own diges- tive actions on those set up by the organic diastases. Neither the diastases of the ferments nor those of the oro-anism ever cause a disengagement of gas, and the carbonic anhydride and hydrogenated gases formed in the intestine must be attributed to the microbes living therein (DuCLAUx). As to the secretion of Branner's glands we know little, but it is stated that an extract of the gland digests fibrin in an acid solution (G-rijtzner) ; Costa states that these glands yield mucin, and Eabuteau and Leven that its reaction is acid. Brunner's glands are related structurally to the pyloric glands of the stomach, and as the latter possess a peptogenous o 2 106 DIGESTION' AND THE SECRETIONS CONCERNED. power (Heidenhain), possibly tliey are likewise related in fiiiic- tion. The surface cells also of the duodenum near the pylorus are said to contain pepsin. Budge and Krolow found tli-it a watery extract of Brunner's glands converted starch into dextrin and sugar, and fibrin into peptone. Iodides, bromides, sulphocyanides, and lithia salts absorbed in the stomach appear again in the small intestine (Quincke). The secretion obtained fro m the large intestine is mucous, viscid, alkaline, and contains very little albumin ; it is said to possess the power of converting starch into sugar, but it apparently exercises no solvent action on albumins or fats. CHAPTER X. THE BILE. Physical Properties. — When the bile flows from the liver it is clear and syrupy, of a golden brownish yellow colour (greenish in herbivora), having a sweetish bitter taste, a specific gravity of 1009 to 1020, and a neutral or weakly alkaline reaction (but slightly acid in the carnivora). After having lain some time in the gall bladder the bile becomes concentrated, has a sour smell, is darker in colour, charged with mucus, and may con- tain particles of fat and calcic phosphate. Absorption Spectrum. — Perfectly fresh normal bile gives no absorption bands, although ox gall, even when fresh, is said to give a band between D and e ; but when the bile has altered, as by standing for some time, or when an alcoholic extract is used, it becomes dichroic, green in thin and red in thick layers, also altering in colour through green and blue to a reddish tint, and shows four absorption bands — one in front of c, one on each side of d, and one before e, only the middle two being dark and sharply defined. Amount. — Very various estimates have been given, but the average may be taken as 1,000 to 1,700 grams (2-2 to 3-7 lbs.) in the twenty-four hours. Nasse estimated it at 45 to 47 oz. for rilE BILE. 1«)7 a man of 142 lbs. weight, Kanke at 23 oz. for a man of 104 lbs., and Witticii obtained nearly the same result in a woman with a biliaiy iistula, the bile of the twenty-four hours contain- ing about ^ ('Z. of solidji and averaging about 2*2 per cent, of the l)0(ly weight. Secretion. — The liver receives a large amount of blood, which is especially abundant during digestion, although it is comitaratively poor in oxygen, yet rich in materials absorbed from the alimentary canal. The secretion of bile is continuous, but it becomes more active two hours or so after a meal, and this activity continues to increase for the following five to seven hours, but then diminishes rapidly. According to Eee^abd the maximum period is seven hours after, but authorities differ. The pres- sure under which it is secreted is very low, and accordingly its flow is easily obstructed. But although secreted continuously with varying rapidity it is only discharged into the intestine at intervals as required, an accumulation occurring in the gall bladder. The passage of the acid chyme from the stomach over the orifice of the bile duct acts as a reflex stimulus to the contrac- tion of the gall bladder, and to a consequent outpouring of the bile. Chemical Composition. —The three i important constituents of the bile are the biliary acids, the biliary pigments, and the cholesterin, but the two former are the most characteristic. In addition we find lecithin, cholin, fats, soaps, a diastatic ferment in small amount, and different salts. Human Bile (Frerichs, Gorup Besa.nez, &c.) Per cent. Water 86 to 90 Solids 14 „ 10 Biliary acids and salts Fats Cholesterin . Mucus and pigments Mineral salts Solids in Hitman Bile. — The amount of solids in the bile obtained from dead bodies is much greater than that contained 5-6 , , 10 0-3 , , 1-7 0-4 , , 1-0 1-4 „ 2-9 OG , , 1-0 198 DIGESTION AND THE SECRETIONS CONCERNED. in bile flowing away from a fistula ; in the latter the solids form only 1-2 to 2*3 per cent., while in the former they are as high as 10 to 14 per cent. It is very probable, however, that this is nearer the normal condition than is the case with the fluid discharged by an open fistula. In 2)ost-mortem bile Hoppe Seyler obtained — Per cent Glycocholate of soda . 303 Taurocholate „ . 0-87 (containing sulphur) ..... . 0-05) Soaps . 1-39 Mucin . 1'29 Lecithin .... ... . 0-5.3 Cholesterin . 0-35 Other organic substances insoluble in alcohol . 0-U Iron, probablj' as phosphate .... . 0006 In 100 parts dry solids of bile obtained from a fisttda, having a specific gravity of 1010 and 2'2tl: to 2*28 per cent, of solids, Jacobsen got— Sodic chloride .... ■±-t o 24-5 Palmitate and stearate of soda 6i Phosphate of soda 5-9 Carbonate „ ... 4-2 Cholesterin 2-5 Phosphate of lime 1-S Potassic chloride .... 1-2 Lecithin 0-2 Fats 0-4 Pucsidue insoluble in alcoliol and ether 8-1 In this analysis Jacobsen found no sulplmr, but in several other analyses he obtained a large percentage of this body, pointing to the presence of much taurocholate of soda (so also Bischoff). A varia- tion in the relative proportions of these two biliary acids is possibly produced by the character of the food. Indeed, Jacobsen has not found the composition of human bile to be very constant, the biliary acids varying from 3-9 to 10*8 j^er cent., and the specific gravity, which generally averages 1017, may be as low as 1010. The percentage of sulphur in bile varies between 1*88 and 3'41, and of nitrogen between 7'23 and 10'66 (Spiro). In fuller detail the cliwf constituents may be said to be — 1. liesinoiis acids, the so-called biliary acids, which exist in the bile as soluble alkaline salts; for example, glycocholate of soda, C2Gll4 2NaNO(,. Of the two biliary acids most modern analyses in- THE BILE. ](I0 dicate the glycocholic as preponderating in human bile. The mean of six analyses gave a percentage of G-47 biliary acids, of which the taurocholic formed 1-56 per cent., containing 009 per cent, of sulphur (Jacobsen). 2. Pvjnienfs — bilirubin, biliverdin, and sometimes bilifuscin. 3. Mucin. 4. Cholesterin. This is maintained in solution by the taurocholate of soda. It is stated to form 1-6 per cent, in human bile (Flint), and is probably one of the decomposition products of nerve sub- stance. 5. Lecithin; probably c/i^o^iM or neiirin, nn alkaline basic deriva- tive of the lecithin; a small quantity of urea, and of fots existing chiefly as alkaline soaps. 6. The mineral constituents are formed chiefly by sodic chloride, which with soda salts constitutes over three-fourths of the ash of bile; there are also alkaline salts of the fatty acids, and pho.sphates of lime, magnesia, and iron, 7. Gases. The bile contains a large amount of gases, partly dis- solved in and partly combined with it. In the rabbit the freshly secreted bile contains an avei-age of 109 per cent, carbonic acid, and in the dog about 57 per cent. ; only traces of oxygen and nitrogen are present (J. J. Charles). In some animals a dia.static ferment has been obtained from the bile. In adult men the bile is poorer in water and fats, and richer in biliary acids, pigments, mucus, and mineral salts than in women and children ; no proteids are present under normal conditions. In ox bile taiu-ocholate and glycocholate of soda are present, in .sheep's bile the taurocholate prepondei'ates, and this is the only acid present in dog's bile, while in the bile of pigs we find hyoglyco- cholate and hyotaurocholate of soda (C27H43NO5 and ('97114.5^80,3). Effect of Food, &c. — Abstinence lessens the amount of bile formed ; with a fatty diet little bile is secreted, but more with a diet of bread and rice ; a rich nitrogenous diet increases the amount as well as the solid constituents, but a good mixed diet (as bread and meat) seems to be the most effective (Wolff). The composition of the bile, besides being affected by the character of the food, is also influenced by the period of its secretion, the acids appearing to be increased during digestion, then diminished in amount, and increa.sed again after several hours (HOPPE Seyler). Watery solutions of the biliary acids injected into the 200 DIGESTION AXD Till: SECIiETIONS CONCERNED. blood increase the biliary acids in the bile (Huppert) ; the same effect is likewise produced by injecting bile into the small intestine (Schiff). An increase of the pigments occurs after the injection of oxyhaemoglobiu or bilirubin solutions into the blood (Tarchanoff). Action of the Human Bile. — 1. Emulsifies fats to a slight degree ; also dissolves them slightly, particularly the three fatty acids, both saponifying and emulsifying, especially in presence of pancreatic juice. 2. Aids in the absorption of fats, as membranes moistened, with bile admit the passage of fats more readily. In chyle, for instance, which normally contains 3*2 per cent, of fats, the proportion is reduced to 0*2 per cent, when the flow of bile into the intestine is stopped. 3. Checks putrid ferm^entations and acts as a natural stimul- ant to the intestinal mucous membrane. The biliary acids are powerful antiseptics, especially the taurocholic (Maly, Emich). 4. The bile 'precipitates all the pepsin in the chyme enter- ing the small intestine, and if the chyme is neutralised or rendered even slightly alkaline peptones or syntonins will also be precipitated. The pepsin, which would interfere with the action of the trypsin, is thus disposed of. The partially digested food passing from the stomach is accordingly well prepared for the action of the pancreatic and intestinal juices, the presence of bile, so detrimental to gastric digestion, rather favouring the action of these juices. In some animals bile converts starch into sugar. Role of the Bile in the Economy. — In addition to assisting in the digestion of the fats the bile also serves to excrete different decomposition products from the system. The greater part of the biliary acids is reabsorbed and further oxidised, the intermediate jn-oducts between them and carbonic anhydride and water being unknown ; the remaining portion is decomposed and excreted. Excreta and vomited matters sometimes, but particularly in diseased conditions, may contain traces of the biliary acids, but their decomposition products (as cholic and choloidic acids and dyslysin) are more likely to be found than themselves. Tlie i)igments are reabsorbed in part, and in part also, together with the cholesterin, excreted in the fa?ces. THE BILE. 201 But it is very pr()l)ablc that sevei-al of tlio ingredients of the bile are repeatedly absorbed and re-excreted during the process of digestion. Source and Production of the Biliary Constituents. — Hie hiUarij acids are not met with in the blood, although glycocin and taurin, albumin derivatives, are possible constituents of parts of the organism ; these acids (or at least cholic acid) are secreted by the hepatic cells, at the expense probably of an albuminoid, the nitrogen radicle being derived therefrom, while the cholic acid radicle may be derived from the fiats, the combination of the two being effected in the liver. Among the decomposition products of cholic acid lauric and stearic acids have been obtained (Tappeinek). Some of the hajmoglobin as well as of the fibrin disappear from the blood in its passage through the liver, and the bilirubin is possibly indirectly derived from the former. Hfematoidin, C3oH34N.,06 ; Hfematin, Ca.iHg^FeN.iO^ ; Bilirubin, CgaHajjISr^Og. Its source is regarded as the hEemoglobin of the blood that is broken down in its passage through the liver. The injection into the blood of solutions of bodies capable of dissolving the coloured cor- puscles, and thus setting free the hsemoglobin, has been found to cause bile pigments to appear in the urine. Tarchaxoff obtained an in- creased discharge of the bile pigment by injecting bilirubin or oxy- ha^moglobin into the veins of a dog. But the spectra of htematoidiu and bilirubin are quite distinct (Preyer). We cannot do more, therefore, with our present knowledge, than regard the above hypo- thesis as to the origin of bilirubin as probable. Much of the choleslerin, if not all, is possibly merely excreted by the liver ; it is most likely a nerve derivative, and in some conditions of nerve irritation it is said to be greatly increased (Flint). The mucin comes from the epithelium of the biliary passages and not from the hepatic cells. Tests and Reactions. — To obtain bile for analijsis, dilute some of the fresh secretion with water, and treat the mixture with spirit or dilute acetic acid ; shake well and filter. The filtrate will serve for the general tests ; but to obtain purified bile for analytical purposes mix the bile with 5 times its volume of absolute alcohol ; filter after some time, and evaporate the filtrate to dryness. The residue dissolved in water gives the reactions well. The tests for bile depend on the identi- fication of two of its constituents, the biliary acids and the pigments 201' DIGESTION AyjJ THE SECRETIONS CONCERNED. The presence of biliary acids is generally ascertained by the red or piu-}»le coloration given with sulphuric acid an'l sugar — Pettenkofer's test, which has been variously modified — while the pigments are gene- rally detected by the play of colours given with an oxidising reagent like nitric acid. The Pettenkofer's test as applied to urinary products is fomewhat deceptive, as the urochrome, itc, yield red and purple colorations with sulphuric acid ; but doubt can be set at i-est by the use of the S})ectroscope, bile giving a broad dark band overlying D, two or thi'ee other bands occasionally being seen. A great many organic bodies besides the biliary acids give purple colorations with sul- phuric acid alone, or with sulphuric acid and sugar ; but such bodies are rarely met with in bile or biliary urine. 1 . Pettenkofer's Reaction for the Biliary Acids. — (a) Add to some bile in a test tube, or to a fluid containing it, a little sugar, then an equal volume of strong sulpliuvie acid, which is to be allowed to trickle doA\Ti the side of the inclined tube : a strongly coloured layer forms immediately above the level of the acid, which takes a purple tint on slight agitation. This purple layer gives two absorption bands, one near E and the other beside f, when examined spectroscopically (Scheis'k) ; but it has also been given as a band outside d and a broad band at e (MacMunn) ; and according to Heynsius and Campbell in the case of sodium taurocholate there are three bands, one between c and D, a second between D and e, and a third near f. These bands are not given by the purple-coloured fluid obtained in the same way with albumins, &c. ; further, the red fluid obtained in Pettenkofer's reaction is dichroic, while that got with albumin, &c., is not so. (6) Dip a piece of filter paper in the diluted bile after having added to it a little cane sugar ; dry the paper, and place a drop of sulphuric acid upon it : a violet red colour will appear in a few seconds (Eosenbach and Strassburg\ (c) Place a little bile, and about two-thirds its volume of sulphuric acid, and one to two drops of a solution of cane sugar (10 per cent.) in a dish over a water bath ; heat u]) to 70°, and a purple violet coloration will be obtained. The presence of nitrates or chlorates interferes wath the reaction. (cZ) I have employed the following modification of Petten- kr)fer's test for seme years past, and have found it work deli. THE lilLi:. 203 cately and satisfactorily. As it depends on the coloration of the froth obtained by shaking the fluid containing the bile, it is often advisable, so as to obtain as permanent a froth as pos- sible, to mix the biliary fluid with a little mucilage of gum arable before adding the syrup, though if much bile is present this is not necessary. The test tube must next be vigorously shaken for a short time, and when a deep layer of froth has formed a few drops of strong sulphuric acid are allowed to trickle down into it, when a beautiful violet or purple coloration will make its appearance, either at once or after the side of the tube has been very gently warmed. 2. Gmelin's Test for the Biliary Pigments. — Nitric acid added to bile gives a precipitate which disappears on the addi- tion of fresh acid, a play of colours being produced — green, blue, violet, red, and finally yellow. This test may be applied in various ways. A very good plan is to spread a drop of the diluted bile on a white porcelain dish, and then allow a drop of yellow nitric acid to flow into it, when the rings of colour will appear at the point of contact. 3. Absorption Spectrum of Bile. — ^Hepatic bile is clear, but after having lain in the gall bladder it becomes darker coloured, denser, ropy, and charged with much mucus. When fresh it gives an absorption band between d and e, but nearer D. After some time the bile alters, becoming dichroic and presenting four absorption bands. Examine also a filtered dilute hydrochloric acid extract of dog's bile with the spectroscope, and a narrow band will be found between h and f. Before applying any of these tests to fluids containing bile, it is often advantageous to separate the biliary acids and pig- ments, which is particularly necessary when the amount of bile present is very slight. 4. Separation of some of the Biliary Constituents. — Dilute some bile with water and add alcohol : a ^jrecipitate of mucus occurs ; filter, and to a little of the filtrate add hydrochloric acid, when glycocholic acid will be thrown down in flakes ; to the rest of the filtrate add acetate of lead solution : glycocho- late of lead will be precipitated, and from the filtrate tauro- cholate will be obtained by the addition of subacetate cf lead. 204 DIGESTION AND THE SECRETIONS CONCERNED. 5. 2^0 Analyse the Bile (Gorup Besanez). — (a) Weigh 20 grams in a tared capsule, and having evaporcxted to dryness heat the residue for some time to 110°; weigh on cooling. [b) Exhaust the dry mass with absolute alcohol, and collect the insoluble residue, which consists of mucin, a little pigment, and. in- soluble salts ; dry and weigh as before ; then incinerate in a platinum capsule : the salts I'emain behind. (c) The alcoholic extract is evaporated to a small volume, excess of ether added, and the mixture laid aside for several days ; decant the ether carefully and wash repeatedly with fresh ether. The precipitate consists of the salts of the liliary acids. Dissolve in a little alcohol, evaporate in a porcelain capsule, and having dried the residue weigh. {d) The ethereal extract is to be distilled, the residue well dried over sulphuric acid in vacuo, and weighed ; it consists of cholesterin, fat, and lecithin. To separate the fat and lecithin fi"om the choles- terin boil gently with caustic potash, which saponifies the fat and lecithin ; shake Avell with a little Avater, and then with ether to dis- solve up the cholesterin; the ethereal extract is to be evaporated, and the residue, when washed with a little water, dried at 100°, and weighed, gives the cholesterin. 6. To Detect Bile in Vomited Matters. — The bile, if present, gene- rally imparts a green colour and a bitter taste to the fluid ; much mucus also is usually present. Shake up the vomit with water and filter through a linen cloth ; precipitate the filtrate with plumbic acetate, and wash the precipitate on a filter ; then digest it with sodic carbonate to remove the pigment, and evapoi-ate to dryness ; treat the residue Avith alcohol, filter, and evaporate the filtrate. The residue dissolved in a little water is then tested for biliary acids. Pathology. — 1. The total amount is probably diminished in tlie l)eginning of fevers. 2. The solids are increased especially in severe abdominal affections, in certain diseases of the heart where the hepatic circulation is embarrassed, in cholera, and in retention of bile ; but they are dhiinished in pneumonia, tubercle, dropsy, and diabetes. 3. The biliary acids and pigments are much diminished in typhoid fever, and the bile in this disease, as well as in typhus, may become acid. The pigments may be wanting in fatty degeneration of the liver, and the biliary acids may disappear in some cases of amyloid degeneration. The pngments are increased, often more than doubled, in jaundice. Bile has a solvent action on the coloured corpuscles of the blood, and it is })ossible that in cases THE BILE. 205 of jaundice this solution may occur. 4. Leucin, tyrosin, and much fat may be i)resent in typhus and typhoid fever. 5. Crys- tallised fat or halls of fat may be met with in tuberculosis. 6. Sugar and glycogen may appear in diabetes, as well as after injection of sugar into the veins ; both are diminished in fever. 7. Albumin is occasionally present in fatty de- generation of the liver, in Bright's disease, and after the injec- tion of much water into the veins. 8. Urea may appear in the bile in Bright's disease, cholera, &c. In certain chronic affections the flow of bile is hindered, and it becomes concentrated, frequently leading to a deposit of cholesterin crystals, crystallised fat being frequently formed under similar circumstances. The same has also been noticed in chronic nephritis and hydrothorax. The amount of bile, but chiefly its water, is increased by the ingestion of such bodies as calomel, podophyllin, aloes, rhubarb, scammony, taraxacum, and different laxatives (Scott, Rutherford, Rohrig). Bile acids, when injected, tend to destroy the blood cor- puscles, as well as to produce parenchymatous degeneration of the glands and muscles ; and, by acting on the cardiac ganglia, cause a slowing of the pulse (Legg, Steiner) ; a spasm of the respiratory muscles is likewise said to be produced, and the urine becomes darker in tint. Biliary calculi are rounded, ellip)Soidal, or polyhedric, generally smooth, but sometimes covered with small mulberry- like projections, and either crystalline or amorphous in struc- ture ; they are of all sizes up to that of a nut, though occasion- ally much larger ; their number also varies, as many as 7,000 having once been found in a gall bladder (Otto). These cal- culi are formed by the deposition in the insoluble state of cer- tain of the constituents of the bile around flocculi of mucus or epithelium. The most frequent are cholesterin, bilirubin, bili- verdiu, and carbonate of lime. The dark-coloured calculi are richest in bilirubin, while the pale and often crystalline calculi are chiefly cholesterin. Most commonly these different bodies are present in varying proportions in the same calculus ; thus in man they consist most frequently of cholesterin (generally over 95 per cent.) mixed with varying amounts of pigments 20G DIGESTION AND THE SECRETIONS CONCERNED. and lime salts. Calculi of carbonate and phosphate of lime are the least frequent. jMost biliary calculi contain traces of fat, biliary acids, mucus, and epithelium in addition to their chief components. Calculi of the ox usually contain very little cholesterin, about a half or a third of their mass consisting of bilirubin combined with lime. CHAPTER XI. THE BILIARY ACIDS. The bile of most animals contains alkaline salts of taurocholic and glycocholic acids. Both bodies are characterised by the readi- ness with which they can be split up by their hydration under the influence of prolonged boiling with alkalies or mineral acids. 026^43^0, + H,(3 = C,,H,„03 + C,H,NO, (gl3'cocholic acid) (cholic or cholalic acid) (glycocin) C,eH,,NSO, + H,0 = C24H40O5 + C,H,NS03 (taurocbolic acid) (taurin) The prolonged action of these reagents may cause the cholic acid to be broken down still further and furnish a resinous pro- duct, dyslysin (C24H3g03), insoluble in water and alcohol, but readily soluble in ether ; indeed, cholic acid under the influence of heat alone, or of heat and hydrochloric acid, may be thus decomposed. In human bile a body called anthropoglycocholic acid (C18H2SO4) has been described (H. Bayer). Possibly much of the biliary acids secreted in the bile, par- ticularly the glycocholic, is absorbed again and re-excreted, the absorption occuriing chiefly in the jejunum and ileum, for SciiiFF found that the establishment of a biliary fistula in a dog quickly lowered the total amount formed, but that this was as quickly raised if the bile was re-injected into the small in- testine. TArPEiNER's experiments also prove the same thing. In human bile glycocholic acid is much in excess of the taurocholic (SocoLOFF, Trifaxowski, Jacobsen). THE BILIARY ACIDS. 207 Preparation. — Different methods have been given, of wliich a few have been selected wliich the author has found effective, 1. Evaporate ox bile to a thick syrup, stirring it frequently with a glass rod, digest this with cold absolute alcohol, which leaves the pigments, part of the mineral salts, and the mucus undissolved ; then filter the alcoholic extract through animal charcoal, or shake it well and boil it with the charcoal, and filter. This alcoholic extract may also be made by rubbing up the bile with sufficient animal charcoal to form a paste, which is to be well dried over a water bath, reduced to a powder, and then extracted with absolute alcohol. The alcoholic extract having been made, the alcohol is to be dis- tilled off, the dry residue dissolved up in a little absolute alcohol, and the solution treated with ether until it becomes markedly turbid. A whitish mass is deposited in a few hours or days, which gi-adually assumes more or less of a crystalline appearance. This is Plattner's crystallised bile, and consists of a mixture of glycocholate and tauro- cholate of soda. By dissolving this in a small volume of water, adding a little ether and then dilute sulphuric acid, and stin-ing well, glyco- choUc acid crystallises out in shining needles, the taurocholic acid re- maining in solution ; the crystals may be collected on a filter, washed with w^ater, redissolved in very dilute spirit, and precipitated with ex- cess of ether. Or to a solution of Plattner's crystals add neutral and then a little basic lead acetate, when (jlycocholate of lead will be thrown down • collect on a filter, wash, dissolve in hot alcohol, and remove the lead by passing a current of sulphuretted hydrogen through it ; filter, and by the careful addition of water to the alcoholic filti-ate crystals will be deposited. To the previous filtrate from the glycocholate of lead add acetate of lead and ammonia, collect the taurocholate of lead pre- cipitated, and wash and decompose it as with the glycocholate, 2. Evaporate ox bile nearly to dryness, extract with alcohol (90 per cent.), filter, distil off the alcohol from the filtrate, and treat the residue with water ; to the watery solution add some milk of lime warm gently, and filter. When the yellowish filtrate cools treat it with excess of dilute sulphuric acid until a permanent turbidity ap- I^ears, Lay aside until a crystalline precipitate forms, which will occur sooner or later. Collect and wash it on the filter with cold water ; it is then to be expressed, and dried between folds of blottino-- paper, dissolved in excess of lime water, and again treated as before with dilute sulphuric acid. The ylycocholic acid precipitated after some time (days, or even weeks) becomes crystalline, 3, The concentrated fresh ox bile is poured into high narrow glass cylinders, covered with ether, and then ti-eated with a suffi- 208 DIGESTION ANl) THE SECRETIONS CONCEENEl). ciency of hydrochloric acid (2 c.c. acid to every 40 c.c. of fresh bile). The bile becomes crystalline. Pour off the ether, and shake the residue with much water ; collect it on a filter, and wash it there with cold water until the washings are colourless; now dissolve the residue in hot water and filter. When the filtrate cools the (jlijcocholate will crystallise out. 4. Evaporate dog's bile to a syrup, exhaust this with alcohol, and shake the alcoholic exti-act with animal charcoal to decolourise it ; then evaporate to dryness, redissolve in a little warm absolute alcohol, filter again, and precipitate with excess of ether. The pigment may be removed, as in method 1, by first making the bile into a paste with the charcoal, then evaporating to dryness and extracting the dry residue with a little absolute alcohol, to which excess of ether is to be added. The precipitate of taurochoUc acid, which appears slowly, assumes a crystalline character ; to purify it dissolve in a little water, precipitate the solution with basic lead acetate and ammonia, and wash the deposit with water ; then digest it with boiling absolute alcohol and filter hot ; pass a cvirrent of hydric sulphide through the filtrate and separate the lead sulphide by filtration ; this last alcoholic filtrate is to be evaporated to a syrupy consistence at a low temperature, and the taurochoUc acid thrown down by the addition of excess of ether. Properties.— (a) The glycocholic acid exists in two forms, one of which crystallises in very fine needles, and the other is amorphous, appearing as a resinous mass. It is monobasic, and enters into combination with the alkalies and alkaline earths, also -with silver and lead. This acid is soluble without alteration in hydrochloric, sulphuric, and acetic acids and gly- cerin ; easily solulsle in alkaline solutions, with the formation of salts ; very slightly soluble in cold, but more soluble in hot water ; almost insoluble in ether, but very soluble in alcohol. Its alco- holic solution exei-ts right-handed polarisation =29°, the gly- cocholate of soda being =25-7°. This acid appears to be absent from the bile of carnivora, but it is abundant in ox bile and in human bile. (6) The taurochoUc acid {choleic acid, Stricker), or at least its soda salt, forms silky needles that deliquesce readily in the air, foiining an amori)hous mass Ihat soon passes into a syrup, being very unstable, and decomposing readily into taurin and cholalic acid. It is soluble in water and alcohol, and TIIK BILIARY ACIDS. i>(X) polarises to the right, its soda salt in alcoholic solution having a specific polarising power of 24'5°, but in watery solution only equal to 21-5°. It combines with potash, soda, and baryta, and its solutions are precipitated by basic acetate of lead and am- monia, but not by neutral acetate, like the glycocholate. This acid is especially plentiful in the bile of the carnivora, being the only one present in dog's bile ; but it is to be found also in ox and human bile. Tests for the Biliary Acids. — 1. To the solution of the biliary acids add a little solution of cane sugar, and then drop liy drop strong sulphuric acid : a white cloudy appearance is produced, which disappears with excess of acid, a deep piu"ple violet colour being produced. 2. If present in small amount in a liquid, evaporate this, and digest the residue with alcohol, and evaporate the alcoholic residue in turn. Add a few drops of water to the dry extract, and then a drop or two of syrup (1 to 3 water) ; let strong sul- phuric acid now fall drop by drop into the mixture, and an orange colour, rapidly passing through a carmine to a purple tint, shows itself, but soon disappears. The quantity of water must be small, and the temperature below 60°. The reaction can often be satisfactorily obtained by adding- a drop of sugar solution (1 per cent.) and a drop of sulphuric acid to the dry residue, and gently heating over a water bath until a violet red coloration begins to show itself at the margin of the liquid, when the capsule is to be removed and laid aside. The colour increases in intensity. The charring of the sugar (as in the case of diabetic urine) liy the sulphuric acid sometimes hinders the characteristic reaction, particu- larly if the temperature i-ises too high ; so Dreciisel has proposed the use of a syrupy solution of phosphoric acid instead of the sulphuric, the heat being applied as before. In addition to the biliary acids, oleic acid, cholesterin, lecithin, ben- zin, phenol, turpentine, camphor, salicylic, tannic, and pyrogallic acids, morphia and various fats are said to give Pettenkofer's reaction with sugar and sulphuric acid ; and with sulphuric acid alone the reaction can be obtained with cod-liver oil, cerebrin, salicin, piperin, etc. The latter bodies appear, therefore, to contain a radicle related to sugar. The coloured body produced appears to depend more on the constitu- tion than on the composition of the product (Kingzett). P 210 DIGESTION AXD THE SECRETIONS CONCERNED. By means of the spectroscopic test any diificulty with regard to the possible presence of albumins, fatty acids, amyl alcohol, &c.,may be avoided, as a moderately strong solution of the biliary acids gives an absorption band between D and E, but nearer E, and a second beside F towards its red side (Schenk). 3. The amount of biliary acids present in bile or in a liquid can be determined approximately by means of the polariscope with an «x56-4 ,.,.., .,, 1 alcoholic solution: j>= .^^ . , «= deviation in degrees with a 1 decimetre tube. 4. Quant itativz Determination of Taurocholic Acid. — By burning a •weif^hed quantity of diy bile, which has been freed from every trace of sulphuric acid by baryta water, with nitric acid, the sulphur of the taurocholic acid is oxidised. Digest the residue with water and determine the sulphuric acid by baryta (see Acidimetry). 98 parts sul- phuric acid=3:i sulphur, and 1 part sulphur=16'8 taurocholic acid. Derivatives. -j. CHOLIC or CHOLALIC ACID, YLG ^,11,^0^ + 11.2^? is principally interesting as being the starting point of tlie biliary acids. It is the constant product of the decomposi- tion of the biliary acids, and accordingly is found in the intestinal contents, and occasionally in the urine of jaundice, but it is not present in fresh bile nor in the organism. It is readily obtained by the action of acids or boiling alka- . lies on the biliary acids, but Bayer affirms that the cholic acid derived from the human biliary acids is quite different to that prepared from ox bile by Strieker's method, and Hammarsten agrees with him in this respect in some points. It is prepared by boiling bile with caustic potash for 12 to 24 hours ; then precipitate with hydrochloric acid, and having washed the deposit with water dissolve it in caustic soda containing a little ether ; hydrochloric acid is next added, and after some time crystals form ; decant and cover the residue with ether, drain off the ether in half an hour or so, and dissolve the deposit in boiling alcohol ; to this solution add a little water until a permanent precipitate appears : tetrahedric crystals soon make their appearance. Properties. — It is almost insoluble in water, soluble with difficulty in ether, and moderately soluble in alcohol. Cholic acid occurs in an amorphous as well as in three crystalline forms ; it is monobasic, and by prolonged boiling with acids and alkalies, as well as by putrid decomposition, it is transformed THE BlLlAliY ACIDS. 211 into choloidic acid {C.^JJ^J^^i) and later into dyslysin (Cj^H^gOg). If nitric acid is employed, and the boiling continued for five or six days, a good condenser being attached to the vessels,acetic and other volatile fatty acids are evolved, and cliolesteric (^\Hj(,Or,) and chohiidnnic acids (C,gH240^) remain behind in tl;e retort. ij. For GLYCOCIN, one of the decomposition products of glycocholic acid, see under Hippuric Acid, p. 463. iij. TAURIN, C,H.NS03.— This body is found in the in- testinal canal, kidneys, spleen, lungs, and in putrid but not fresh bile, being developed at the expense of the taurocholic acid when the bile ferments. It is isomeric with isethionamid, and ammonium isethionate when heated to 210^" to 220° is converted into amidethyl sul- phonic acid, or tamin — '"^"^ ( S03NH, - "2^ + ^2"^ 1 S03H Preparation. — Concentrate fresh ox or dog's bile and boil it several hours with dilute hydrochloric acid, adding water from time to time to replace the loss by evaporation ; dyslysin separates, and afterwards some sodic chloride ; decant and filter, evaporate the filtrate to dryness, and digest the i-esidue with absolute alcohol, which precipitates the taurin and removes the glycocin chlorhydrate. The residue, in- soluble in the alcohol, is dissolved in water and left to crystallise, when more sodic chloride separates, the taurin remaining in solvation. To the decanted liquid add 4 to 5 times its volume of lx)iling alcohol, which takes up the taurin, this body afterwards separating in prismatic crystals when the alcohol cools. To purify it the taurin may he repeatedly dissolved up in water, and crystallised out by the addition of alcohol. Properties. — Taurin crystallises in large four- or six-sided colourless prisms soluble in hot water and insoluble in alcohol ; it is not decomposed by boiling dilute acids or alkalies, but nitrous acid breaks it up into isetbionic acid, water, and nitro- gen. Combinations with soda, lime, silver, lead, and mercury, &c., are known as — C,H,(Na)NS03, (C,H,NS03).,Ca, (C,H,NS03),Hg-f HgO. p 2 21-' DIGESTION AND THE SECREriONS CONCERNED. CHAPTER XII. THE BILIARY PIGMENTS. The tM'o normal pigments are bilirubin and biliverdin, but the freshly secreted bile poured out during digestion which has not lain in the gall bladder appears to contain biliruliin alone. Two others are described by Stadeler, bilifuscin and blliprasin, which are met with chiefly in biliary calculi ; bili- hurnin has also been described, and Hammaesten further giv^es hydrobilirubin. These pigments play the role of weak acids. According to Stadelee the following relationship exists among some of these colouring principles: biliverdin is bilirubin +0 and HgO ; biliprasin the same, only with an additional mole- cule of water ; and bilifuscin, bilirubin + 2H2O. Bilifuscin (C,gH2oN204) is found in small quantity in old bile obtained from the 'post- mortem room, and in human gall stones; biliprasin (CigH22N20g), in human gall stones in small amount ; while bilihumin is an impure product. Bilirubin, of which the rest seem to be derivatives, is closely related to hgematin, a derivative of haemoglobin — 3(C3,H3,N,FeOg) + 3H2O = 6(C„H.,N203) + 3FeO. (hfemalin) (bilirubin) BILIRUBIN (Bilphaein, Bilifulvin, Cholepyrrhin), CigHjgNaOg or C9H0NO2 (Thudichum). — This pigment is present in the free state in the bile of man and carnivora, but more abundant in ox bile ; also in large amount in gall stones, particularly those of a dark colour, in which it is partly combined with some of the alkaline earths, &c. It constitutes the chief biliary pig- ment, and is probably more or less identical with hsematoidin, the blood crystals found in old extravasations (Valentinee). Preparation. — 1. Powder richly coloured hiliary calculi, particu- la^-hj thosK of tJie ox, and exhaust the powder with ether, and subse- quently with boiling water, to which a few drops of hydrochloric acid should be added to separate the bilirubin from its combinations. Wash it now in pure water and dry it. The residue is next boiled with chloroform and filtered ; from the filtrate the chloroform is dis- tilled off, and the residue extracted with absolute iilcohol and ether, THE BILIARY PIGMENTS. 213 by which bilifuscin is removed, the bilirubin remaining behind. It may now, to purify it, be redissolved in chloroform, and the solution allowed to evaporate spontaneously for some time, and then the bili- rul)in thrown down as an amorphous orange pi'ecipitate by the addition of alcohol (after Stadeler). Some of the bilirubin may be obtained in the crystalline form by allowing part of the chloroform solution to evaporate to dryness. The residue after the chloroform extraction contains generally a green colouring matter, hilijvasin, which can be removed by means of alcohol, the alcoholic extract evaporated, the residue puritied with ether and chloroform, and then dissolve! up again in a little cold alcohol. After the action of all these solvents upon gall stones a brown body, hilihnmin, usually remains behind. 2. From Human Bile. — -Add an excess of alcohol, and then a little ammonia and calcic chloride, filter, and exhaust the precipitate with alcohol. The residue is treated with dilute hydrochloric acid, and after having been washed with water is extracted with alcohol, which dissolves out the bilifuscin, while the insoluble part is digested with chloroform, which dissolves up the bilirubin (Thudichum). Or dilute the bile with water, precipitate with milk of lime, then pass a current of carbonic acid for some time to separate the lime, and filter ; decompose the precipitate with a little hydrochloric acid, then shake it up with chloroform, and after having evaporated off much of the chloroform precijjitate the bilirubin with alcohol, 3. It can readily be extracted from fiesh dog's bile by acidifying this with acetic acid, adding chloroform, then warming gently and shaking well in a flask. Allow the chloroform extract to settle, and remove it with a pipette. The bilirubin can be separated from the chloroform by evaporation or precipitation with alcohol. Properties. — It forms a tine orange or red amorphous, or a dark brownish-red, crystalline powder, the crystals forming rhombic tables or prisms, soluble in the alkaline carbonates and precipitable therefrom by hydrochloric acid ; readily soluble also in chloroform and benzole, although its alkaline com- binations are insoluble in these reagents; but very sparingly soluble in alcohol and ether. Its colour is evident even in very dilute solutions. Bilirubin acts the part of a weak acid, and combines with soda, lime, silver, baryta, lead, &c., as (C„H,,N,03),Ca. Derivatives and Characteristics. — 1. Add some moderately 2U DIGESTIOX AND THE SECRETIONS CONCERNED. strong yellow nitric acid, drop by drop, to an ammoniacal solu- tion of bilirubin ; a green coloration appears, which rapidly changes to a blue (bilicyanin), a violet, a red, and then an orange and yellow tint. Zones of colour will also be obtained by placing drops of the bilirubin solution and of yellow nitric acid in contact upon a white plate. The final product of- the reaction is called choletelin (Ci6^i8^2^o) by jNIaly. It is a yellowish brown amorphous body, soluble in water, acids, and alkalies, and it is stated by Maly to be identical with the urinary pigment. Into hydro- bilirubin it is convertible by the action of water and sodium amalgam, and this in turn reconvertible into choletelin by nitric acid. Choletelin gives one broad band extending from 6 to a little beyond f. Jaffe's urobilin also gives a band at f. While choletelin is the final oxidation product, urobilin appears to hold somewhat of an intermediate position. Another secondary product of the oxidation of bile pigment is described by Stokvis as insoluble in ether and chloroform, but forming a rose-red solution in caustic soda, which gives a broad band in the green between D and e ; but this pigment is not found in urine un- less in pathological conditions. 2. Add to a solution of the bile pigments in alcohol, ether, or chloroform an alcoholic solution of bromine (5 per cent.) or an aqueous solution of chloric or iodic acids (20 per cent.), and three stages of coloration will be produced — green, blue, and violet — after which a reddish yellow colour shows itself, and lastly the whole becomes colomiess. The blue solution gives one band in the red when examined with the spectroscope ; the violet solution two bands, one in the red and the other in the indigo ; and the reddish-yellow solution a single band in the blue (Capeanica). 3. Add a little sodium amalgam to an alkaline solution of bilirubin, and heat gently or lay aside for two or three days ; the colour will gradually disappear. The mercury is then separated by decantation, and hydrochloric or acetic acid added until a precipitate occurs in the form of reddish brown flocculi, that are to be separated by filtration. This body is hydrobiii" TILE BILIARY riGMENTS. 215 ruhin (C32H44N4O-), said to be identical with Jaffe's urohilin (Stokvis) and with the colouring matter, stercobilin, of the faeces (Masius). According to Hoppe Seyler a similar body can be prepared by acting on ha:'moglobin or haematin with hydrochloric acid and tin. HYDROBILIRUBIN (Stercobilin) is dark brown and amor- phous, and soluble in alkalies, sulphuric and acetic acid, and alcohol, ether, and chloroform. The solutions are generally rosy red in thin layers ; but they do not show a play of colours with nitric acid. Its acid solutions are said to give an absorp- tion band, especially on the addition of a little chloride of zinc, between b and r, but close to the latter. Hydrobilirubin is occasionally present in bile and urine, but is usually present in faeces, being formed there probably by the action upon the bilirubin of the nascent hydrogen evolved in butyric acid fermentations. BILIVERDIN, GieHj.N^O, (Maly), CieH^oNoO, (Stadelek), CgHgNOg (Thudichum). — This body is abundant in the bile of cold-blooded animals, as well as in that of warm-blooded animals who are starving. An alkaline solution of bilirubin, when exposed to the air, becomes greenish from the formation of biliverdin. The action of light alone has been said to be sufficient to induce the change (Capraxica). Biliverdin is prepared by making an alkaline solution of bilirubin, passing a current of air through it or exposing it to the air for some time in a flat vessel until it becomes intensely green ; then precipitate with hydrochloric acid, wash the deposit with water until no chlorine reaction can be obtained in the washings ; finally dissolve in absolute alcohol and precipitate with water. Properties. — Biliverdin forms a green amoiphous powder, and is insoluble in water, ether, and chloroform ; it is very soluble in alcohol (particularly if freshlj prepared), acetic acid, and alkaline jfluids. Like bilirubin it gives a play of colours with nitric acid, and from it hydrobilirubin and choletelin can be obtained. Relations among the Soluble Pigments of the Body. — It is supposed that the bile pigments are derived from those of the blood, and give origin to the pigments of the faeces, from which 21G DIGESriOX AXn THE SECRETIONS CONCERNED. come the colouring matters of the mine. The order of their appearance would, therefore, be somewhat as follows : haemo- globin, hfematin or haematoidin, bilirubin, hydro-bilirubin, and urochrome. As yet, however, the connection has not been clearly proved. CHAPTER XIII. CUOLESTERIN. CHOLESTERIN, CggH^^O, is very widely spread in the body, and in the seeds of plants it has also been found. It occurs laro-ely in the cerebro-spinal axis and in nerves ; is also present in blood and is possibly excreted in the bile, forming the chief ingredient of biliary calculi. Its natm-al solvents in the bile are the soaps and biliary acids. Cholesterin is likewise found in yolk of egg, in the spleen, in certain dropsical fluids, pus, atheromatous deposits and strumous cysts, and in many lipomas, goitres, and pulmonary tubercular deposits. Preparation. — 1. Powder some pale biliary calculi, boil the powder some hours Avith spirit to which potassic hydi-ate has been added ; jS.lter on cooling, and wash the crystalline mass with cold alcohol and then with water ; purify the cholesterin thus obtained by redissolving it in boiling ether, adding to this last half its volume of alcohol, and lay aside to evaporate spontaneously. 2. It can also be readily obtained by extracting brain substance. The pieces of brain are to be placed in alcohol for several days, and then to be finely divided and digested in boiling alcohol ; \\\e hot ex- tract is next filtered through a heated fumiel, and the filtrate allowed to cool. The deposit that occurs consists of cerebrin and protagon as well as cholesterin. This is first washed with cold alcohol, and after being dried with filtering paper is shaken with ether, the ether distilled oflT and the residue heated for an hour with an alcoholic solution of pota.'-sic hydrate ; it is then evaporated to dryness, waslied with water, and dissolved in a mixture of ether and alcohol, from which the cholesterin is allowed to crystallise out. Properties. — Cholesterin has the character of a nionatoniic alcohol, seeming to be the only free alcoliol tliat occurs in CIIOLESTERIX. 217 the body. It is a fatty substance insoluble in cold water, alka- lies, dilute acids, and alcohol, but soluble in a large quantity of boiling water or in boiling acetic acid, glycerin, or alcohol ; also readily so in ether and chloroform, benzole, soaps, and the biliary soda salts. It exists water-free or combined with a molecule of water. Out of benzole, chloroform or anhydrous, ether it crystallises without water, but water holding crystals are deposited from alcohol in the form of oblique rhombic tables. From a mixture of alcohol and ether it separates in monoclinic prisms or large pearly plates. The usual crystals are the large, thin, trans- lucent, and mother-of-pearl-like rhombic tables. The anhydrous silky needles are not so common. Fig. 17.— Cuy^'ials df Choijestkeix. Heated up to 350^ in vacuo it sublimes in great part with- out alteration, and yields cholesteric acid (CgHmOg) when boiled with nitric acid ; when heated to 200° with such acids as acetic and benzoic it forms compound ethers, and a resinous hydrocarbon (CjgH^g) appears when it is boiled with strong sul- phuric acid. Tests and Characteristics. — 1. Add a little dilute sulphuric acid to a few crystals, warm gently, and then add a drop of strong sulphuric acid : a deep red colour is developed. This test can be well applied to a few crystals placed on a slide and ex- amined under the microscope. Add to the crystals a drop or two of strong sulphuric acid diluted with one-fifth its volume of water ; after mixing with a glass rod heat the slide gently. The edges of the crystals will be seen under the microscope to have become violet or carmine-tinted (Moleschott). 2. When the crystals are heated with moderately strong sulphuric acid and afterwards with a little iodine, a play of 218 DIGESTION AND THE SECRETIONS CONCERNED. colours is produced, passing from violet through blue, green, red, and yellow to brown. Concentrated sulphuric acid colours the crystals red, the tint being changed to green on the addi- tion of water. 3. Dissolve some crystals in chloroform, and shake the solu- tion with an equal volume of strong sulphuric acid : a blood red solution is obtained, which becomes blue, then green, and finally yellow. A trace of water decolourises the solution at once (Schiff). The layer of sulphm-ic acid presents a well- marked green fluorescence ; on diluting it with glacial acetic acid a rosy and then a purple liquid makes its appearance, but the fluorescence remains permanent (Salkowski). 4. Heat some crystals gently with a mixture of ferric chloride (1) and hydrochloric acid (2), and they will, if pure, assume a violet or bluish colour. 5. Place a few crystals on a small porcelain dish, cover them with a drop of strong nitric acid, and evaporate to dryness at a gentle heat ; on touching the yellow residue before it has quite cooled with a drop of ammonia a deep red colour is pro- duced, which is not altered by the addition of a drop of caustic potash — thus differing from murexid (Schiff). 219 BOOK III. THE TISSUES: CHEMISTRY OF THE TISSUES, ORGANS, AND REMAINING SECRETIONS. CHAPTER I. THE BLOOD. Functions. — 1. Serves as the great medium of exchange among all the parts of the body. 2. Acts as the great carrier of nutrient fluid to the tissues. The blood is elaborated from the food, and serves as the intermediary between it and the fluid in which the tissues and organs are bathed, and from which they obtain their nutri- ment. Waste is constantly going on, and this waste material is as constantly, during life, being replaced by new material supplied by the blood. 3. It is also the great oxygen-carrier. In the lungs the hsBmoglobin fixes a certain amount of this gas. and conveys it to the interstitial fluids. By means of the oxygen thus con- veyed oxidations are carried on in the tissues, by which the latent energies there present are converted into heat and the vital forces. 4. It further serves, like a drainage system, to carry away the waste jproducts, such as carbonic acid and the like, to those parts of the economy, as the lungs, kidneys, &c., where they can be eliminated or prepared for elimination. Physical Characters. — Blood is an opaque, viscid, red fluid, slightly alkaline in reaction, saltish in taste, possessing a mean density of 1055 and a temperature between 36-5° and 37*8° (97-7° to 100° F.) 220 TISSUES, ORGANS, AND REMAINING SECIIETIONS. {a) Its colour is due to tlie hsemogiobin that it contains, and to the condition in which this body exists, whether chiefly in the state of oxyhsemoglobin or of reduced haemoglobin, the degree of colour also depending more or less on the proportion between its coloured and pale corpuscles, and on the greater or less concavity of the former. Arterial blood is of a bright scarlet ; venous blood of a dark bluish red colour ; arterial blood is also monochroic, while venous blood is dichroic — that is, red with reflected and bottle green with transmitted light. The colour of arterial blood is darker in advanced pregnancy and paler in chlorosis, leukaemia, and diseases of the spleen. Venous blood from the kidney is lighter in colour than other venous blood, and the same may be said of venous blood from an inflamed organ. (6) The odour of fresh blood somewhat resembles that of butyric acid, and it is readily evolved by treating the blood with sulphuric acid, being probably due to some volatile body of the fatty acid series. (c) The density may vary between 1045 and 1075 (or 1050 to 1059, Nasse and Schmidt), or an average of 1055, being somewhat less in women and children. The corpuscles have a density of 1088 to 1105 ; the 'plasma, of 1027 to 1028 ; and the serum, of 1026 to 1029, or an average of 1028. {d) The temperature is due to the oxidation going on in the tissues. The temperature of the blood of the hepatic and portal veins is higher than that of ordinary venous blood, and the blood of the right ventricle is warmer than that of the left. (e) The alkaline reaction is due to the bicarbonate of soda and sodic phosphate of the plasma. The alkalinity increases in the serum after coagulation, but the fresh blood is more alkaline immediately after removal than after a short time has elapsed (Zuntz). To show this alkaline reaction (1 ) treat some glazed violet litmus paper with strong sodium chloride solution, then touch it with a drop of blood to which a fresh drop of the sodium chloride has been added, and in a few seconds wipe away the whole by means of filter paper ; the litmus paper will be seen to be coloured blue by the blood (Zuntz). (2) Let a drop of blood fall on a tiiin slal) of plaster of Paris which has THE laOOD. 221 been previously treated with neutral litmus solution. On wash- ing the drop away a blue stain remains behind (Liebreicii). INIaly regards the ordinary method of titration of serum as not trustworthy, and his experiments would tend to show that the scrum has acid instead of alkaline properties. Hinteregger has shown that acids and acid salts disuse more readily than neutral salts ; therefore serum containing acids ought to yield an acid diffusate. This Maly has found to be the case: 350 c.c. of serum dialysed in distilled water yielded a ditFusate contain- ing sufficient acid to neutralise 212 milligrams of soda. Quantity of the Blood. — Very different estimates have been given, but the most reliable appear to be founded on the data of Welcker and Heidenpiain, &c. ; according to these the blood forms 7-7 to 8*3 per cent, of the body weight of an adult man ; that is, for a man about ten stone weight, about eleven pounds of blood. This corresponds very closely to Bischoff's estimate of one-thirteenth of the body weight. A new-born child contains in its body only a proportion of 5*2 per cent., or about one-nineteenth of the body weight ; a dog about 7'4 per cent., and a rabbit 5*5 per cent. Distribution. — It may be stated in general terms that about one-fourth of the blood is normally present in the liver durino- life ; one-fourth in the muscles of the skeleton ; one-fourth in the heart, lungs, and great vessels, and the remaining fourth in the rest of the organs and tissues. Microscopic Constituents of the Blood. — These consist of a series of little bodies called coi-pusdefi, which float in the liqiior sanguinis. Of the corpuscles there are two chief varieties, the coloiired or red and the pale or white. (a) The coloured corpuscles vary in shape and size thi-oughout the vertebrata ; they are circular hollow discs in all the mammalia except the camelidse, in which they ax-e oval, and they are oval in shape in birds, reptiles, and fish. In man they have an average diameter of ^Jp^th to ^xr^th of an inch. In all the vertebrates except the mam- malia the corpuscles are nucleated, but it should be mentioned that a body resembling a nucleus is said to be brought into view, even in a mammal's red corpuscle, by a special treatment (Bottcher). These coloured corpuscles consist of a pale translucent white protoplasmic substance, the stroma, which is everywhere permeated by the red colouring substance of the Itlood, the haemoglobin. No separable cell- 222 TISSUES, ORGANS, AND BEMAINING SECRETIONS. wall is present, altliough something of the kind has been described in the red corpuscles of reptiles, and even of mammalia (Ranvier, Eutherford). Some small granular coloured corpuscles have also been mentioned as existing in the blood; to these Hayesi has given the name of hcematohlasts. (b) Of the ])ale corjjuscles thei-e are different vaiieties. They are nucleated masses of protoplasm devoid of cell membranes and con- taining fine or coarse granules ; they possess the power of amseboid movement, and can take substances into their interior. Intermediate forms also exist ; and Ranvier describes two forms of free gi-anula- tions, the one rounded and the other angular. ^U 5400 1000 Fig. 18.— Blood Cokpcscles. (a to/ human, g to I frog, and m pigeon.) a, red or coloured human corpuscles seen on the fiat ; 6, a louleau of human corpuscles seen on the flat ; c, a red corpuscle seen in profile ; d, a crenated red corpuscle ; e, pale corpuscles, one of which is coarsely and the other finely granular; /, free granulations ; g, red corijuscles of frog ; /(, red corpuscle of frog seen in profile ; i, dead pale corpuscle ; k, resting pale corpuscle ; /, pale corpuscle in a state of a!ctivity, exhibiting amoeboid movement ; m, red corpuscles of pigeon. As a mean there is about one pale corpuscle to 340 red; but the pale corpuscles are increased by food, and the proportion vaiies ac- cording to the region whence the blood is derived : thus in the splenic vein there is 1 to 60 red, in the hepatic vein 1 to 170, in the portal vein 1 to 740, and in the aorta 1 to 2260. (Jhemical Composition. — Normal blood left to itself for twenty- four hours gives the following percentages : — /,. . . ( serum = 44-525 Liquor sanguinis \^^^^ ^^(■oA\ I 1 i- .^ tf r/> /^ moist corpuscles Corpuscles J clot = 475- 50 =85_36 ' j interstitial serum ( = 12-5-20 The chemical compoeition varies somewhat in different animals, and even in the same animal tliere are sensible dif- ferences not only according to the region whence the blood is THE BLOOD. 223 taken, but also according to the physiological or pathological condition of the animal at the time. Analysis— Blood of Adult Male (at. 25). (C. SCHMIDT.) Per cent. Per cent Plasma .... .r. ^^ \ water . . 48-69 ,., 'solids . . 43-90 . 4-79 Moist corpuscles . 51-3 r''^^ ■ ■ ■ ^^•^ I solids . . 34-97 . 16-34 CorpLiscles Per cent. Plasma Per cent. Water . 68-16 90-15 Solids . 31-84 9-85 Globulin, &c. . Hajmatin 29-60 ^lb"ii^'ns , -^ Albuminates l-oO ^ Extractives [ 8-19 (or Hcemoglobin = 31-11) Fibrin . 0-81 Ash ... . 0-73 0-85 Potassic chloride . 0-367 0-036 Sodic „ — 0-55 Potassic phosphate . 0-234 — Sodic „ . 0-063 0-027 Soda . . 0013 0-15 Potassic sulphate . 0-013 0-028 Calcic and magnesic phos- phate . 0-015 0053 The amount of corpuscles in this analysis appears very high ; in another analysis of the blood of a woman, aged 30, Schmidt obtained the proportions : — Other chemists have given the mean of the plasma to the corpuscles as : plasma, 65- 67 per cent. ; corpuscles, 33-35 per cent. Plasma . Moist corpuscles 60-38 39-62 The ash of the serum as compared with that of the corpus- cles is rich in soda salts and chlorine, but poor in phosphates and sulphates. It is possible, it may be remarked, that in the process of calcination the sulphuric and phosphoric acids are in- creased at the expense of the carbonic acid that is expelled, the chlorine at the same time diminishing sensibly. Analyses, at any rate, make the proportion of phosphoric acid in the corj)uscles to that in the plasma as = O'llS per cent, to 0*019 per cent.; and of the potash in the corpuscles to that in the plasma as = 0-332 per cent, to 0-032 per cent. On the other hand, in the plasma the proportion of soda and chlorine is about three times as great as in the corpuscles ; and there is also in the plasma an excess of the earthy phosphates. •2-2i TISSZ'ES, OliGAXS, AM) REMAI2slNG SECRETIONS. Subjoined is the mean composition of tJie blood as given by Becquerel and Rodier :- Per cent Water 78-10 Diy coipiiscles ..... 13-51) Albuminoids 7 00 Fibrin 0-25 Fats 0-17 Extractives 0-84 "Earthy phosphates .... 003 Iron 0-05 The ash of human blood is thus given by Jarisch in the 100 parts :— Chlorine . 30-74 Potash . . 2()-r)5 Soda . 2111 Phosphoric acid .... S-82 Suli)huric » • • • • . 7-11 Oxide of iron .... 8-in Lime and mj\gnesia . 1-33 1. As to water, the blood of the hepatic vein conta.ins less than that of the portal vein. Fasting from solids and liquids causes tlie quantity to diminish; abstinence from solids alone increases it at first, but then causes it to sink. 2. Fats are present in an average pi-oportion of 0-2 per cent., and consist of palmitin, stearin, olein, and phosphorised fats analogous to those in the bi'ain. They are especially abundant after food, and may thus rise to 0*4 to 0-G per cent., and are richer in portal than in hepatic blood, and also in the blood of females than of males. Alkali soaps of the above fats ax^e also found in the blood. 3. Extractives. — Under this head are included all the organic con- stituents with the exception of the albumins and fats. Cholesterin exists in the corpuscles as well as in the serum ; it varies from 002 to 003 per cent., and is said to increase in old age. Lecithin is probably a derivative of the destroyed corpuscles. AVea^m=0■108 to 0055 per cent, in the blood of tlie ox. Crea forms 0'02 per cent, of the total blood (0'0192 per cent, in blood of Jofy — WuRTz) ; it is richer in placental blood. A ])tt/alin-like/er7ue'iit has been separated ; also a saccharine hody of the nature of (jrape suyar, forming about 05 per cent, of the total blood (0-04: to 0'07 per cent. — Pavy, Dupre), but disappearing very rapidly after death unless the corpse is maintained at a temperature below 0°. "While the portal blood contains little or no sugar, that of the hepatic vein contains from ^ to 1 per cent, of yugar in the dry THE BLOOD. 225 residue. There is much difFerence of opinion as to the amount of sugar : being, according to some, most abundant in tlie hepatic vein, and then gradually disappearing, but more in arterial than in venous blood (Bernard) ; while, according to others, there is no constant difference in the amount of sugar in arterial and venous blood (Pavy, Abeles). Carotid. Per cent. Jujnilar vein. Per ceut. Right ventricle. Per ceut. According to Berxard . . Oil to 0-15 006 to 012 „ Merixg . 017 „ 013 0-11 „ 015 „ Abeles 0049 — 0054 Lactic acid, xanthin, hijpoxanthin, alcohol, and indican are all de- sci-ibed as present; also a yelloiD pi(jme7it, probably an oxidation pro- duct of haimoglobiu, or hydrobiliiubin according to Maly. 4. Inorganic Salts. — A mean of 09 percent, to the 21 per cent, of solids ; more abundant in hepatic venous blood than in portal blood, and richer in the latter than in the serum of the blood of the jugular. Sodic chloride forms about ^ per cent, of normal serum ; sodic carbo- nate and suli)hate are also present in small proportion ; the sodic phosphate probably exists as Na^HPO^, and the traces of magnesic and calcic phosphates as Mg32P04 and Ca32P04 ('() respectively. The arrangement of bases and acids given in blood analyses, it should be remembered, is artificial and approximative, and cannot be said to be really a correct representation of the condition in which these bodies are present in the blood. Both phosphates and sulphates, for example, are no doubt derived in great part from the oxidation of the lecithin and proteids, &c. ; the iron from the haemoglobin ; and the earthy phosphates in part from the fibrin and albumin, being set free by these bodies when they coagulate. The Corpuscles. — These bodies constitute from one-third to a little less than one-half the whole blood. The blood of birds is richest in corpuscles, but not so rich in hfemoglobin as the corpuscles of human blood, which is richer in corpuscles than the blood of any other mammal. The red corpuscles, as we have seen, are made up of a colourless stroma, consisting of globin or a globulin-like body or bodies, which must not be confounded with the paraglobulin of the serum, although the latter may be derived from it. This globin is impregnated with htemoglobin, and contains in addition traces of other bodies. Tlie moist corpuscles of human blood contain about 35 percent. dry solids. The dried organic matter, according to Judell, con- sists in the 100 parts of— Q L>26 TISSUES, ORGANS, AND REMAINING SECRETIONS. HiBmoglobin 86-79 to 94-30 Albuminous bodies and nucleiir . . 5-10 „ 12-2i Lecithin 0-35 „ 0-72 Cholesterin ...... — 0-25 There are also present alkaline chlorides and phosphates, a little fat, and traces of manganese and of a diastatic ferment. Nucleated corpuscles are said to be richer in albumin, choles- terin, and lecithin ; and in their nuclei a body named nuclein (Plosz) has been described as present. This nuclein resembles mucin, but differs from it in containing phosphorus. The average of iron in the blood is said to be 0*054 per cent. (Pelouze), and in the dry corpuscles 0*43 per cent. (Boussin- gault). The coriiposition of the pale corpuscles can only be arrived at indirectly. They consist of several albuminous bodies, fat, lecithin, glycogen, and other extractives, together with potash phosphates, &c. Tlie Plasma, at a temperature below 0°, is a viscid, greenish yellow or yellowish fluid, strongly alkaline in reaction, and separating into fibrin and serum if the temperature is only a little raised above 0°. The generators of this fibrin, according to Schmidt, are fibrinoplastin (paraglobulin), fibrinogen, and a special ferment. Of these only the fibrinogen is said to be preformed, the fibrinoplastin and the ferment resulting from the rapid destruction of the pale corpuscles. In men the amount of fibrin that can be separated forms a mean of about 0*2 per cent, of the total blood ; but arterial yields more than venous, and the blood of the jugular vein more than that of the portal. Its quantity is increased by animal to a greater extent tlian by vegetable food ; it also increases in pregnancy. The Serum is a transparent yellowish or greenish yellow fluid, alkaline, slightly viscid, and consisting of water about 90 per cent., holding in solution 8 to 10 per cent, of proteids and 1 to 2 per cent, of fats, extractives, and salts. Arterial serum contains more water than venous serum, and the water increases in old age (Simon) Three alhumins are described as present — serum albumin (serine), paraglobulin (fibrinoplastin), and alkali albuminate (serum casein). Hammarsten gives the total albumin as equal THE BLOOD. 227 to 7*62 per cent., of which serum albumin forms 4*51 and serum globulin 3*10, the globulin therefore bearing the pro- portion to the serine of 1 '. 1*51. Weyl considers that there is only one globulin in serum, seriirti globulin^ fibrin and fibrinoplastin being merely this body mixed with some fibrin ferment. The ser~albumin is soluble in water, and is precipitated by boiling, coagulating at about 71° in presence of a little acetic acid. The paraglobulin possibly comes from the coloured cor- puscles (Kuhxe) and is precipitated by a current of carbonic acid gas passed through the serum diluted with ten times its volume of water. The alkali alhv/niiii is thrown down by the addition of acetic acid to the filtrate after the separation of the paraglo- bulin. Traces of peptones are also occasionally met with. The Gases of the Blood. — In the following table is given the average of a series of experiments (3ch6ffer, Preyer, Pfluger, Sczelkow, &c.) with the blood of dogs and sheep, the results being calculated in percentages at 0° and 760 mm. I. Arterial Blood. Total volume of gas disengaged in vacuo = 49 per cent. Nitrogen . . . . ^ 2-47 Oxygen . . . . = 15-65 Free carbonic acid = 30-88 \ Carbonic acid dis- engaged by the |- = 34-00 action of acids in vacuo . .= 3-12'' Making a total . . . = 55-12 per cent. II. Venous Blood. Total volume of gas disengaged i/t vacuo = 50-74 per cent. Nitrogen . . . . = 1-38 Oxygen . . , . = 936 Free carbonic acid = 40-00 , Carbonic acid dis- engaged by the ;- = 46-15 action of acids in vacuo . .= G15' Making a total . , . = 5689 per cent. Q 2 228 TISSUES, ORGANS, AND REMAINING SECRETIONS. The average iu human blood at 0'^ and 760 mm. may be thus stated ( Foster) : — Oxygen Carbonic acid Nitrogen Arterial blood . 20 per cent. 89 per cent. 1 to 2 ^jer cent. A^enous „ . 8 to 12 „ 46 „ 1 „ 2 Or at 0° and 1,000 mm. (according to the German method) — Oxygen Carljonic acid Arterial blood 16 per cent. 30 per cent. Venous „ 6 to 10 35 Tims arterial blood contains on an average about 7 per cent, more oxygen and 6 jjer cent, less carbonic acid gas than venous blood. The amount of oxygen varies according to the number of coloured corpuscles — that is, to the quantity of haemoglobin — in the blood, and depends greatly on the region of the body fi-om which it is taken : for example, in the carotid artery the oxygen is present in the proportion of 21 per cent.; in the renal artery, 19 per cent.; in the renal vein, Avhen the kidney is active, 17 per cent,, and when in a state of rest, 6 per cent. ; in the splenic ai-tery, 14 per cent, ; in the splenic vein, when the spleen is active, 1 1 per cent., and when at rest, 4 per cent. ; the blood of the femoral artery also, when com- pared with that of the carotid, contains much less oxygen. Fur- ther, the state of the health and the character of the food appear to afiect the amount and character of the gas considerably. The oicjfjen is comhined toith the licenioglohia, with the exception of a slight trace that is in a state of solution ; accordingly corpuscle- holding serum absorbs 5 times as much oxygen as ordinary serum. 100 grams of haimoglobin crystals dried between folds of blotting-paper yield 41*3 c.c. oxygen; and after having being dried in vacioo at 0°, 31 "2 c.c. 100 grams of dried and deoxidised htemoglobin removes from water, saturated with oxygen betsveen 0° and 20°, 133 c.c. oxygen at 0° and 1,000 mm. pressure (Preyer) — that is, 1 gram can combine with about 1'3 c.c. of oxygen. The combination, however, is 80 loose that the hoemogloljin easily parts with its oxygen to bodies possessing a gi-eater affinity for it than the htemoglobin itself; it can therefore be completely extracted in vacito or by placing the blood in an atmosphere of carbonic oxide. As to the carbonic acid gas, a varying but presumably a small proportion is in a state of solution, while the rest is in loose combina- tion, associated probably with some salt or .salts iu the serum, the condition of the comljination apjieaiing to be determined in some way by the action of a constituent of the corpuscles. The serum of dog's blood contains about 35'2 per cent, carbonic anhydride, 2*24 THE BLOOD. 229 per cent, nitrogen, and 0*26 per cent, oxygen (Pfluger.) With what salt exactly the cirbonic acid is combined is doubtful — whether with soda as bicarbonate, or with sodic phosphate, &c. ; some authoritie.s even being of oi)iiiion that a portion of the gas is combined witli the corpuscles, and the rest partly in a state of combination and partly in a state of solution in the plasma. The degree of pressure has a considerable effect on the amount of gas present in the blood, particularly the quantity of oxygen, as a reduction of the pressure to half an atmosphere is said to reduce the oxygen to half its normal amount. According to Bert the proportion of the gases in the arterial blood of a duir is — CO, N A.t 1 atmosphere . . 20-2 371 1-8 ,, .0 atmospheres . 23- 7 35-5 6-7 „ 10 . 24-7 37-9 9-8 Changes in the Blood Gases in Respiration. — 1. The blood in passing throng-li the lungs takes up 8 to 12 vols, per cent, of oxygen ; its reduced haemoglobin is thus in great part converted into oxyhsemoglobin. This excess of oxygen in the arterial blood is given up to the interstitial fluids of the body, in which the oxygen tension is very low. How much oxygen is present in the residual air filling the air cells of the lungs it would be difficult to say, but we may safely assume that it does not fall below 10 per cent. The tension of oxygen in the. arterial blood is about 4 per cent, and in the venous about 3 per cent, (in the arterial blood of the dog its average is 3-9 per cent., and in the venous 2*9 per cent.), and therefore the difference in tension will be sufficient to lead to a rapid inter- change or equalisation of tension. 2. The blood having become charged with carbonic acid by its interchanges with the interstitial fluid of the tissues, in which the carbonic acid is in a high state of tension, parts with its excess of carbonic acid at the lungs. Whether this separation is more than a simple case of diffusion it is difficult to say, but the tension of the carbonic acid in the venous blood is much higher (5'4 per cent, in the dog) than that of the carbonic acid in the residual air. Some assume the occurrence of a temporary increase of car- bonic acid tension in the lung, resulting from the action of 230 TISSUES, ORGAXS, AXD REMAIXIXG SECRETIONS. the corpuscles, the puhiionary epithelium even having been assumed to possess an eliminating function. How the Constitution of the Blood is affected. — The con- stitution and characters of the blood are modified considerably according to circumstances. Normal influences alone will here be considered. I. (a) Difference between Arterial ami Venom Blood {GORXJP Besanez). Physical characters and chemical constituents Arterial blood Venous blood Temperature about 1° higher lower Colour . brighter, and not dichroic darker and dichroic Gases . relatively more ox^'gen relatively more carbonic acid Water . more less Fibrin . „ ,, Hiemoglobin less more Albumin no constant difference Fats . „ „ Extractives . more less Urea . less more Salts . more less Sugar . )) " Although arterial blood has proportionally fewer coi-puscles than venous blood, yet those of arterial blood are said to be richer in colouring matters and salts, but poorer in fatty matters than the corpuscles of venous blood (Lehmann). (j3) CJiaracteristics of Portal and Hepatic Blood (C. Schmidt). Constituents Portal blood Blood of hepatic vein Water . more less Plasma ,, ,, SaUs . ,, ,, Fats . >> ,, Moist corpuscles . less more Extractives . » „ Fibrin . present absent Sugar . 1 1 absent, or only in traces abundant (only in traces — Pavy) According to Drosdoff in portal blood there is more hsemoglobin and sodic phcspate and less cholesterin and lecithin than in hepatic bloocl ; further, in the portal blood the proportion of the corpuscles to the plasma is 57-60 per cent, to 40-43 per cent., while in the hepatic venous blood the coipuscles form 74 to 77 per cent, and the pla.sma 23 to 26 per cent. THE BLOOD. 231 Blood of the portal vein coagulates more i-apidly than that of the rvjht ventricle, and its serum is i-eddish ; it contains more water and serum albumin, and is also more charged with fatty bodies, ex- tractives, and salts than the blood of the jugular vein. (y) t^pliic Venous arid Placental Blood. — The splenic venous blood contains more water and fibrin than venous blood generally ; its red corpuscles are diminished and its pale corpuscles increased, and it is comparatively rich in cholesterin. The blood of the foetal placenta is poor in fibiin and albumin, rich in albuminates, and while containing less solids than the niateinal blood it is richer in urea. II. Influence of Sex and A/jr. (a) Human Blood (Becquerel and BoDlEU). Constituents Men Women Water 77-90 7910 Solids 22-10 20-90 Fibrin ......... 0-22 0-22 H;«moi^lobin ........ 13-i.T 1217 Albumins 7-60 7-fiO Cholesterin, lecithin, and fats .... OIG 0-16 Extractives and sails 0(58 0-74 (/3) Human Blood (GoRUP Besanez). Constituents Men Women Children CM age Water less more less more Fibrin — — ,j ,, Corpuscles more less more less Albumins ...... less more „ „ Fats — — Extractives more less Salts •' " less more The solids in the blood of a new-born child are nearly twice as great as those of an adult's blood, but in adults the ash is more abundant than in young animals. (y) In pregnancy the water is increased and the corpuscles diminished; at the period of parturition there is only about 11-3 per cent, corpuscles instead of 13"5 per cent.; after parturition the corpuscles increase. During pregnancy the fibrin is increased, espe- cially in the three last months (0-35 to 0-48 per cent.) ; the albumins are slightly dimini.shed, and the fats and phosphorised bodies in- creased. 1^32 TISSUES, ORGANS, AND REMAIN IX G SECRETIONS. II] . Iiijittcnce of Food (GoViVV Besanez). Constituents During digestion Continue, irregular rliombic tetrahedra, from blood of guinea pig ; <•, six-sided tables from blood of mouse— somowtat similar in thesquin-el ; d, needles from lark's blood ; (',/, elongated four-sided needles, from blood of cat and dog. in others ; these crystals are formed with great difficulty from the blood of the pig, ox, or frog, with some difficulty from the blood of sheep, men, rabbits, &c., easily from that of the doo- or cat, and very easily from that of the guinea pig or rat. 238 TISSUE'S, OliGANS, AND REMAINING SECIiETIONS. ABC These crystals belong mostly to the rhombic system, forming long fom-sided prisms in dogs, tehahedra in guinea pigs, and rhombic tables and prisms in man and the horse. It is stated by H. Struve that freshly prepared blood crystals which have been rendered insoluble by treatment with alcohol are decolourised by ammonia or chlorine water without undergoing any change in their crystalline form. Hence he concludes that the blood crystals consist essentially of globulin mixed with a minute quantity of the red colouring matter of the blood. Absorption Spectra. — Diluted arterial blood or a dilute solu- tion of oxyhasmoglobin gives a double absorption band between D and E, a solution con- taining even 0"05 milli- gram dissolved in 5 c.c. water showing the two stripes. Of these two the narrow one towards D is the more intense, and is the only one visible in very dilute solutions. Kedueed haemoglobin gives but one broad and comparatively faint band, that is darkest in a position intermediate to the situ- ation of the oxyha^moglo- bin stripes, but extending also in a less intense form a little to the red side. of D. Ordinary diluted ven- ous blood will also give the two bands of oxyhajmoglobin, showing that there is still a large amount of this body con- tained in venous blood ; and as these are much more distinct than the faint band likewise faintly visible and due to the large amount of reduced haemoglobin present, the latter is not easily recognised. Besides giving the absorption bands, part of the rest of the spectrum is shut out ; thus with moderately dilute solutions of oxyhaimoglobin part of the red end of the spectrum is absorbed, IH w 11 1 I'iJIIlJli ill if iV'ilj ■ "1 ;;;;;;||pi!l! „, J ,§ |;j| iiiiiijl 1; i 1 ' lii It :!:J f 1 b.. .. :l Fjg. 20. — ABSoiirTioN Spectra of Bloop. 1. Oxylifemoglobin. 2. Ecduced haamoglobin. 3. Al- kaline Iia?matin. 4. Alkaline ha3inatin decomposed with potassic cyanide or potassic cyanba>niatiii. 5. Alkaline solution of reduced ha^niatin (corre- sponding nearly to liiemocbromogen). (i. Hivma- toiii (prepared by the action of an ethereal oxalic acid solution on ha'inoglobin — I'uEYKig— con-e- Fponding nearly with iron-free acid hiematin, the band to the extruiie rifiht of the latter, however, lying more towards r. 7. Methtenioglobiu in alka- line solution (JAnEitnoi.M;. A a. B C I J I b r G WIM MilH;HHI '^PMnVUHH^^^^HRHHHIIBIH^^^^^^BiiHIl HH^HHIIIIHi^ll^HiHHH[lBIHiiHHR° ^Mumm *<•■ IflHIHI ■■ ■ ill II^H I. n. m. "VL. ABSORPTIO'N SPECTRA. OF BLOOD. OiicyhctJifnx'C^Lobtrh. Rexiux-exL k/xpjrboylx>binj. AlhniJjrupj hxx/ejnwdjrt . HcLerrwohit'OTnx>gerv {r'Pjdxtrj^id' twupjutaJburv) . Hafijiifjiit^pcfphyi'ijtv iro ciTb aJhalij-ue. solxihorv. . HaetiLoioui {alJij'jdljix) (t.cifL Tiaernahro). Mintern Br'Os. Chr-omo litK. HJblMOGLOBm. 2.'W and a larger part of the blue end ; with the reduced haemo- globin, on the other hand, less of the blue end is absorbed and more of the green. Carbonic oxide exactly displaces all the oxygen in defi- brinated blood (Berxard), taking the place of the oxygen in the hiemoglobin. The new compound crystallises like oxyhsemo- globin. Blood so treated gives two absoqjtion bands like those of oxyluemoglobin, but the reduction band cannot be obtained with this blood by means of reducing agents like carbonic anhydride, &c., on account of the greater stability of the carbonic oxide ha?moglobin. A slight excess of soda also brightens blood containing carbonic oxide, while it darkens normal blood. Nitric and nitrous oxide also unite with hemoglobin, and with sulphuretted hydi'ogen a sulphur combination of htemo- globin is formed. Derivatives. — Oxyhaemoglobin is decomposed by dilute acids or alkalies, or by the action of heat, into a proteid, globin or glolndln, and a ferruginous pigment, hcematin, of which about 4 per cent, is obtained for about 9G per cent, of the globulin bodies. A watery solution of oxyhasmoglobin soon changes colour, and gives rise to a new body, viet/ircuioglohin, wliich is said to be occasionally met with in cysts and in the blood after the inhalation of amyl nitrite. By the addition of some freshly-pi-epared potassic permanganate solution to a haemoglobin solution methsemoglobin, and later hsematin, are obtained ; nitrites act similarly. Indeed, oxidising substances are said to change oxyhremoglobia first of all into metha^moglobin. This body, about which some donbt exists, is said to be soluble in water, but insoluble in alcohol and ether ; it is split into hsematin and an albuminous body by acids and alkalies, and gives an absorption band in the red between c and D. This body was first described by Hoppe Seyler, but he afterwards regarded it merely as an intermediate stage in the decomposition of haemoglobin into lijematin and proteids, Jaderholm, however, regards it as existing as a definite body, a peroxijhn;mo(jlobin which in an alkaline solution exhibits three bands in the spectrum. A solution of oxyhsemoglobin heated to 100° decomposes, and a red precipitate occiirs, in which luemochromogen is described as present ; and by treating reduced hjemoglobin with acids or alkalies in the 240 TISSUES, OliGAXS, AND REMAINING SECRETIONS'. absence of oxygen it is also obtained (this eoiresponds to the reduced hiematin of Stokes) ; further, when decomposed -with dilute oxalic acid, beside the albumin precipitate thrown down, hcematoporjihyrin is formed (Hoppe Seyler). Proportion of Hceifnoglohin present in Blood. — Haemo- globin may be said to form a little more than 12 per cent, ol' the blood, and about -[-|tlis of the solid constituents of the corpuscles. Taking the proportion present in a new-born child as 100, the following numbers (liEiCHTEXSTEiN) will express the proportions present later in life : — ^ to 5 3'ears = 55 per cent. 5 „ 15 „ = 58 15 „ 25 „ = 61 25 „ 45 „ = 72 45 „ 60 „ = 63 „ The blood of the new-born, we see, is therefore richer in hemoglobin than that of the adult. The proportion is some- what greater in men than in women : men, a mean of 13*58 per cent. ; women, a mean of 12*63 per cent. Assuming the average proportion of haemoglobin present in mammalian blood generally to be 9*4 per cent., in birds the proportion is 7*8, in reptiles 4*3, in amphibia 3*9, and in fish 3*6. According to Bert the blood of herbivorous animals accli- matised at a high elevation is richer in oxygen than the blood of similar animals inhabiting lands near the sea level, 100 c.c. of the blood in the former case containing 16*2 to 21*6 c.c. oxygen, and in the latter only 10 to 12 c.c. In arterial blood the hiemoglobin is nearly all in the state of oxyhaimoglobin, while in venous blood most of it is in the reduced condition. The blood of a corpse only contains re- duced haemoglobin a very short time after death. In animals completely depri\ed of air the hiemoglobin loses its oxygen in less than a minute, owing probably to the rapid consumption of the gas by the tissues. Tests. I. Ozone Test for Hw'moglohin. — This serves also as a test for blood. Oil of turpentine long exposed to air contains ozone. If to some of this fluid we add a little freshlj' prepared HJEMOGLOlilN. 241 alcoholic solution of guaiacum resin (taken from the middle of a large lump), and then a drop of blood, and shake, a dark blue colour results. The hieinoglobin acts as an ozone-carrier to the resin, but it probably also serves as an ozone-former. Some of the guaiacum solution slioidd be allowed to dry on filter paper, and a few drops of blood that has been diluted 20 times or so allowed to fall on it, when the blue reaction will appear at the margins of the drop. According to Pfllger the oxygen is not converted into ozone by tlie haemoglobin, tlie guaiacum reaction being entirely due to the decomposition of the haemo- globin. This test can be applied to a dried blood stain. The stain is moistened, and then after a time washed in a little water. To the decanted liquid add a few drops of freshly prepared tincture of guaiacum and a little ozonised ether ; the mixture immediately assumes a blue or greenish blue tint. II. Absorption Sjjectra of Hcemo(jlobln.— l. Some drops of blood or of a dilute solution of haemoglobin are added to a small test tube nearly filled with water. This is then brought in front of the slit of an ordinary spectroscope, and examined with bright daylight or by means of a good lamp. With a microspectroscope, such as that of Browning or Zeiss, the bands can be still better seen. A vascular membrane such as the web of a frog's foot or the tongue of the same animal may be employed to show the spectrum of living blood. These two bands in the yellow and the green, between D and E, have already been referred to, and are characteristic of oxyhiemoglobin ; they are visible in a layer one centimetre thick of a solution containing y^o^^ P^^ cent. 2. Treat the blood or haemoglobin solution with a reducing agent, such as some drops of ammonium sulphide or of an am- moniacal solution of stannous or ferrous tartrate, prepared by dis- solving ferrous sulphate or stannous chloride in water, and then addinor in succession a little tartaric acid and excess of ammonia : as the result the two stripes disappear, and the single broad band of reduced hjemoglobin takes their place, the darkest point occupying the interval between the position of the two pre- ceding bands, but its lighter margins extending considerably on each side. R 242 TISSUES, OllGANS, AND REMAINING SECRETIONS. 3. Shake up some defibrinated blood with carbonic oxide in a test tube, and examine spectroscopically ; two bands will also be seen, but situated a little more to the right than those of oxyhemoglobin. Allow a moderately dilute solution of haemoglobin to stand for some time, and it will attain a lirownish tint and an acid reaction; it also becomes precipitable by acetate of lead, which does not throw down liEemoglobin ; and it gives an absorption band in the red between c and d. If to a dilute solution of blood a crystal of pure potassic permanganate is added, and the solution then examined with the spectroscope, a band will be seen in the orange, and a second in the position of the broader oxyha;moglobin band, and a third between e and f. This is stated to be due to the presence of methsemoglobin. III. Additional Projjerties. — 1. If a watery solution of haemoglobin is boiled it will be decomposed into albumin and hsematin, a brownish red coagulum separating. The same decomposition is effected b}' the use of strong acids or alkalies. 2. A drop of blood or a piece of rag that has been stained with it is to be placed in a test tube and shaken up Avith a little distilled water after having soaked for upwards of an hour. A few drops of ammonia are then added, the colour being unaffected thereby, and the solution boiled: a turbidity will be produced, of a dirty grey colour ; on the addition of a drop or two of caustic potash the turbidity will disappear, and the solution will be green by transmitted and red by reflected liirht. CHAPTER III. EST! MATT ON OF 1I2EM0GL0BIN. Tins is effected (1) by the estimation of i ' = 1.3-1'J per cent, hfemogiobm. 0-551 ^ ° The author has obtained fairly accurate results by using standard solutions of normal blood instead of hjemoglobin, and also by repeating the experiments in a darkened room, with the same inten- sity of light, &c., as was primarily used in determining the value of f:. Pathology. — Taking the normal amount of dry haemoglobin as 12' 7 per cent. (Ql'inquaxd), in chlorosis it may sink to 7*2 to 4*6 per cent.; in cancer, to 5'7 to 4*3 (in fibrous tumours and cysts, while the haemoglobin may fall to a mean of 8 per cent., in cancerous tumours it may be as low as 4 to 3*8 per cent.); in leukaemia, to 6 per cent.; first stage tubercle, to 10 24G TISSUES, OliGAXS, AM) REMAINING SECRETIONS. per cent., third stage from 10-6 to 4*8 per cent.; in severe typhoid fever (abont the twelfth day), to 1 1-5 per cent. ; and in acute atrophy of the liver, to 8'1 to 6-7 per cent. In cholera it often rises to 15 to 20 per cent. In chronic anasmia Hayem has noticed that there is less haemoglobin in the corpuscles themselves than in tlie normal condition. CHAPTER IV. H JEM ATTN. H^MATIN, C3,H3,N,Fe05 (Cg^Hg^FeN^Oo— Thudichum).— This is a bluish black amorphous body, forming a reddish brown powder that can be heated without decomposition to 180", and which, when burnt, leaves pure oxide of iron behind. It is insoluble in water, alcohol, ether, and chloroform, but easily soluble in the alkalies or alkaline caTbonates ; it is with diffi- culty soluble in acetic or the mineral acids, and hydrochloric appears to be the only one of these that dissolves it without its iron separating. Solutions of hsematin are dichroic, being reddish brown in a thick and olive green in a thin layer. Like hsemo- globin, htematin exists in an oxidised and a reduced condition, freshly reduced hsematin passing rapidly back into the ordinary form. Preparation. — 1. Dilute defibrinated blood with a large quantity of .10 per cent, sodic chloride .solution. The globules swell and separate from the serum. They are washed with saline solution, dried at a low tempei-aturc, and then rubbed up with 15 to 20 times their weight of glacial acetic acid. AYarm over a water bath till the solution is complete; then dilute with five or six volumes of water and lay aside for sevsral weeks, when crystals of chlorhydratc of haematin separate. Decant, purify the crystals by redissolving them in acetic acid, and dilute as before with tive to six volumes of water. Pure haematin can be obtained from these crystals by dis.solving them in ammonia, evaporating the .solution to dryne.s.s, und heating the residue to 1.30°; next digest the dry ma.ss for several days with absolute alcohol at 50°, filter, and the red alcoholic solution will, on evaporation, yield pure hajmatin. 2. Digest coagulatx^d blood, or the separated corpuscles, with II.KMATIN. -247 alcohol containing sulphuric acid, warm gently over a water bath, and filter rapidly : a dark brown solution of hiematin is obtained. 3. Defibrinated blood is shaken with twice its volume of ether . contiiining quarter its bulk of alcohol. Decant after 24 hours, and exhaust the coagulunj with ether containing 2 per cent, oxalic acid. The ha?inatin is precipitated from this by adding to it ether charged with ammonia, and it is lastly washed with water, alcohol, and ether. Derivatives. — By the action of most of the acids — sulphuric acid, for example — a solution of hcematin is decomposed, and iron-free hwnuttln (apparently identical with criieatin, hcemato- porphyrin, and acid hcvmatin) is thrown down, hydrogen at the same time being disengaged, and ferrous sulphate fif the decomposing acid has been sulphuric) formed. This new body is regarded by HoPPE Seyler as being of the same nature as bilirubin. Preyer's hwinatoin is also very similar to this iron- free htematin, like it containing no iron. If some blood or strong haemoglobin solution is shaken up with an equal volume of ether to which a little acetic acid has been added, and the daik-coloured ethereal solution decanted aud allowed to eva- porate over caustic alkali, stellate brown needles will be obtained of this body. Absorption Spectra (see p. 237). — 1. A dilute alkaline solution gives a faintly marked band at d, with much absorp- tion of the blue end of the spectrum. By increasing the strength of the solution the band extends towards C, and with still further concentration broadens also towards E, the red end of the spectrum as well as much of the blue end being absorbed. The same spectrum is obtained with solutions of blood or haemoglobin that have been rendered distinctly alkaline, and then allowed to stand some time. 2. If to some of the above solution of blood or haemoglobin a little strong potassic cyanide solution is added, a broad ab- sorption band raj^idly makes its appearance like that of reduced hfemoglobin, but lying more towards E. Now treat the solution with such a reducing agent as ammonium sulphide : two bands then appear between D and e, very like in their position to the oxyh;emoglobin stripes, but neither of them touching D or E, the narrowest band being separated from D by a considerable interval {cyanhcematin of Laxkester). 248 TISSUES, OliGAXS, AXD ItEMAIXING SECRETIONS. 3. The ethereal sohition of Pkeyer's hcematoin, or a solu- tion of the iron-free or so-called acid hcematin in alkali or in alcohol containing some sulphuric acid> gives four absorption bands — one distinct band in the red near C ; two bands between D and E, of which one is a faint narrow stripe near d, and the other a broad dark band near E ; and an indistinct band in the blue between b and F. But a slight ditference exists between the spectra of the two solutions, for the bands near c and E are broader and more distinct, and the stripe near D narrower and fainter in the htematoin spectrum. 4. Oxy haemoglobin or a blood solution, when reduced by ferrous sulphate, ammonic sulphide, or grape sugar at 40°, gives a temporary intermediate product, Hoppe Seyler's hcemochromo- gen (Cg4H3gN5FeOg), which is apparently identical with Stokes's reduced hcematin ; it gives a dark absorption band between d and E, but nearer. D, and a second faint band extending from a little on the red side of E to the blue side of h. This reduced haematin or haeraochromogen can be preserved some time in alkaline solutions if not exposed to the air, but it will decompose rapidly in acid solutions, hcematopor'phyrin being formed. H.SMATOIDIN occurs in yellow crystals in old extravasations. Its composition corresponds to the formula CggHy^N^Oe, which makes it homologous with bilirubin, but Preyer maintains that they are not identical spectroscopically. Robin regards it as haematin which has lost all its iron and acquired an atom of water. CHAPTER V. HJSMIN. H^MIN (Teichmann's Blood Crystals), C34H3,N4FeO,.HCl, has nol been found preformed in animal bodies; it is a bluish black or dark Itrown, metallic-looking, very stable crystalline powder. In dilute acetic acid, water, alcoliol, other, and chloro- form it is almost insoluble, but soluble in hydrochloric and sulpliuric acids and in solutions of tlie alkalies and alkaline carbonates, but being decomposed in its solution. H^MIN. 2i9 Hfi?min crystallises in numerous forms belonging to the rliombic system ; these are most generally small brown or almost black rhombic prisms or tables. Preparation. — 1. On a smull scale crystals of lireniin can be oV)tained l>y proceediiif,' as in the first of the tests given below, 2. To obtain it in bulk, separate the corpuscles from a quantity of blood, and having decanted the serum, dry the corpuscles over a water bath at 50° ; add a sufficiency of acetic acid to form a solution with the aid of heat. Tliis having been effected, mix the solution with five times its volume of water, and set the whole aside in a cylinder in a moderately cool place. At the end of several days decant and wash the crystalline residue repeatedly with water for a considerable time. 3. Boil 300 c.c. glacial acetic acid in a flask over a water bath, and add to it with frequent agitation 100 c.c. of blood. The haemo- globin is decomposed, and both the hsematin and the globulin remain in solution. Pour the hot fluid into a beaker, and lay aside. Afcer 24 hours a deposit of very small, dark blue, silky crystals occurs; these are to be washed in water by decantation, and finally collected on a filter. 4. Rub up some jiowdered blood clot with one-fifth its weight of potassic carbonate, then digest the mixture at 4.5° with alcohol (93 per cent.) ; dilute the filtrate with its own volume of water and acidify slightly with acetic acid. The brown flocculent precipitate is to be dried, rubbed up with one-fifth its weight of sodic chloride and 20 to 30 times its weight of glacial acetic acid, and the mass digested at 60°. Separate the haemin crystals as above. Tests. — 1. The dried blood is to be powdered, mixed with a few crystals of dried sodium chloride, and gently warmed on a glass slide ; then add a few drops of glacial acetic acid and warm again ; now add some fresh acid, and having applied a cover glass heat once more, when the charac- . teristic crystals will appear. Larger crystals will be ob- tained by repeating the pro- cess several times ; but sometimes this must be done even to render the experiment successful. When fresh blood is em- FiG. 21.— "Rhombic Crystals of H.k.mix. ■2o0 TISSUES, ORGAXS, A\D REMAINING SECRETIONS. ployed the addition of the salt may be omitted. To preserve these crystals they may be sealed up in acetic acid, or the surplus acid may be removed and replaced by Farrant's solution. 2. Take a little hfemin and dissolve it in dilute hydrochloric acid; this solution, when examined spectroscopically, gives a band in the red near c, and a second diffuse band in the broad space from E to f, but also extending towards d. An alkaline solution is dichroic, brown with transmitted and olive m-een with reflected light. CHAPTER VI. COAGULATION. Fresh-diiawn blood begins to set or solidify If minute to 6 minutes after its removal from the living blood vessels, and this coagulation, as it is termed, is completed in 7 to 16 minutes (Nasse). In healthy blood the coagulation occurs slowly, but the blood of delicate persons, or of invalids, women, and children, coagulates more rapidly. This setting of the blood is due to the solidification or separation of the fibrin, which usually occurs at the suiface and periphery, principally at first in the under layers^ of the blood, and spreading from thence upwards and outwards. The clot, the great mass of which consists of corpuscles, the amount of fibrin being very slight, takes the form of the vessel in which the blood is contained. The coloured corpuscles are in greatest numbers towards the base of the clot, while the pale corpuscles, being specifically lighter, are most abundant at the surface; in cer- tain conditions, as in hydrsemia, chlorosis, and pregnancy, as well as in inflammations, owing to the more rapid sinking of the coloured corpuscles, or, as in horses' blood, to the slower occun-ence of the coagulation, the surface may present a yellowish tint, forming the so-called huffy coat. By the contraction of the fibrin threads the serum is squeezed out, and this may continue for twenty-four to forty- eight hours ; but the occurrence of coagulation as well as the COAGULATION. . ->01 completion of the contraction will vary as to time, according to the condition of the blood itself and of its surroundings when withdrawn. Arterial blood, for example, coagulates more rapidly than venous .blood ; and coagulation may be accelerated, re- tarded, or prevented by alterations in the temperature or by the admixture of the blood with reagents of different kinds. Tlius it is accelerated by moderate elevation of temperjlture, occurring most readily about 38° ; by exposure to foreign con- tact, agitation, and the like ; and by the addition of a small pro- portion of different salts. It is possible that these agencies act by favouring the disintegration of the pale corpuscles from which the ferment is derived. Irritation, in short, of every kind would appear to favour the destruction of the pale corpuscles, and thus increase the proportion of fibrin (INIantegazza). On the other hand, coagulation may be retarded or pre- vented by a low temperature (0°), by the addition in considerable amounts of acids, caustic alkalies, and salts such as magnesic sulphate, sodic chloride, &c. ; further, the addition to the blood of sugar or gum in quantity, or of glycerin in excess, as also the passage through it of a current of ozone, delay and prevent coagulation. Additions of water up to half the volume of the blood hasten coagulation, while larger quantities hinder it. The slower coagulation of venous than of arterial blood is dependent not on want of oxygen, but on its richness in car- bonic acid. Want of oxygen in the blood appears to hasten, whilst richness in oxygen delays coagulation (Hasebrock). Theories as to the Causes of Coagulation.-— Without referring to the earlier theories, I shall confine myself to a brief synopsis of a few of comparatively recent date. 1. The influence of the living vessels seems to prevent coagulation during life ; indeed, Brucke was of opinion that the normal living walls of the vessels exerted an active influence in opposing its occurrence. The endothelial lining, however, must be in a healthy condition, for if it undergoes irritation and germination, or is broken through in any way, a clot forms over the altered region ; and ac- cordingly, as in the case of thrombi, clots may form in the living vessels. A normal relation or equilibrium, as Foster puts it, would seem to l)e maintained between the blood and its immediate invest- nient : wlien this is disturbed coaofulation results. 252 TISSUES, OliG.iyS AXD REMAIMNG SECRETIONS. 2. Theory of Z>e«is.— There exists in the ^olasma a substance (j)lasmin) which can be separated by the addition of an excess of sodic chloride ; this precipitate dissolves in water, and the solution coagulates spontaneously, separating thus into ordinary fibrin and a fibrin soluble in solutions containing traces of sodic chloride. When the blood coagulates, this last fibrin remains in solution in the serum. Coagulation, according to this theory, would therefore be due to the decomposition of a body previously dissolved in the plasma. The presence of a soluble fibrin has also been maintained by EiCHWALD, Matthieu, and Urbain, etc., which under certain con- ditions passes out of solution. 3. As soon as the corpuscles lose their vitality much of their globulin escapes from them. In the living circulating blood this globulin is contained in the corpuscles, and accordingly no coagulation occurs until it combines with other bodies normally present in the plasma. Anything, such as foreign contact, leading to an impairment of the vitality of the globule will tend to favour the discharge of its globulin, and the consequent occuirence of coagulation ; while the presence of cai"bonic acid, neutral salts, or sugar in such amount as to render the plasma denser, or to hinder the rapidity of oxidation, will tend to retard the process (Gautier). («) According to Schmidt the presence of three bodies is necessary for coagulation to occur — -fibrinogen^ contained in the blood plasma ; fihrinoplastin, contained in the corpuscles ; and iy, fibrin ferment which cannot be found in the living blood unless, owing to some abnormal condition, it is generated by a destruction of pale corpuscles. A similar ferment is found in all protoplasmic cells, such as those of lymph, chyle, and pus, &c. Both the fihrinoplastin and the ferment, Schmidt alHi-ms, aie derived from the disorganisation of the pale corpuscles, the fibiinogen alone being a normal constituent of the plasma. By the interaction, then, of these previously separate bodies fibrin is formed. During life any fibx^inoplastin formed by the disintegration of pale corpuscles is al\va}'s being oxidised, thus tending to disappear ; but if this destruction of the corpuscles is greatly increased, as by the injec- tion of solutions of pepsin or j^jancreatic juice into the blood, coagula- tion ensues (Albektoni). In addition to Schmidt's three factors a neutral salt like NaCl requires also to be in-esent — is, in fact, essential to the process. Some serous fluids are wanting in the fibrinoplastic substance, and some in the ferment. The quantity of the ferment pi-esent has no influence upon the amount of fibrin formed, but it affects markedly the rapidity of the process ; and the fibrin generated is less in weight CO A G ULA TION. 253 than the fibrinopListin used up, and an excess of this hody is found in the serum after coagulation has occui-red. {b) Hammarsten and Fredericq are of opinion that there is Itut one generator of fibriu, filirinogen, which under favourable circum- stances, apparently associated with the action of a ferment derivative of the pale corpuscles, is decomposed and fil>i"in formed. Fibrin cannot, then, appear in a fluid devoid of fibrinogen, but without the presence of certain derivatives of the pale corpuscles it cannot be formed from fibrinogen alone. Schmidt's fibrinoplastin simply favours the formation of fibrin from the fibrinogen, but its pi-esence has no eftect on the quantity of fibrinogen used up, although it has a marked influence on the amount of fibrin produced. (c) Heynsius believes that the coloured corpuscles play an im- poi-tant role in coagulation, the chief part of the fibrinogen, according to him, being derived therefrom, although Schmidt ascribes the favourable action of the coloured corpuscles to the ferment that comes from them. Hayeji describes under the name of hcematohlaKts a series of small granular coi'puscles which are very delicate in their consLstencv, more or less biconcave and irregular in shape, and either colourless or stained by hjemoglobin ; as to their pre-existence in the living blood there may be some doubt, but Hayem attributes to them an active share in coagulation, as they serve, according to him, as centres from which delicate threads of fibrin radiate, so that coagulation would seem to have its origin in the physico-chemical acts accompany- ing their decomposition. Fibrin. — Human blood furnishes 0-1 to 0'-4 per cent, dry fibrin. If fibriu is left in a moist condition in a warm place it gradually liquefies and becomes putrid, a coagulable albumin being formed as well as butyrate, valerate, and sulphide of ammonium. LuSANNA. regards fibrin as the liquefied and oxidised tissue detritus, tetanised muscle, he states, furnishing tAvice as much fibrin as the resting muscle ; the lymph also more than blood, because it contains more of these waste products; and the arterial blood more than the venous blood, on account of the excess poured in by the lymph. (For fibrin see under Albumins, p. 113.) 2rA TISSUES, OMGAXS, AND liJEMAIMNG SECRETIONS. CHAPTER YII. METHODS AND PBACTICAL EXEBCISES FOR THE SEPARA- TION, PREPARATION, OR IDENTIFICATION OF DIFFER- ENT BLOOD CONSTITUENTS. 1. Albumin of Serum.— Dilute the serum with twice its volume of water, and add very dilute acetic acid until a precipi- tate occurs — this is 'paraglohulin ; filter, and having rendered the filtrate slightly alkaline, dialyse, and after some time con- centrate the contents of the dialyser. To sejxn'ate serum globulin and serum albumin, add to the serum a saturated solution of magnesic sulphate; the serum albumin remains in solution, the globulin being precipitated. The ser-albumin can be separated from excess of salines by dialysis. 2. The Salts of the Serum. — Faintly acidify the serum with acetic acid, boil for some time, and filter ; the filtrate is often termed serosity. The precipitated albumin contains a little fat and some earthy salts, which may be removed by boiling first with alcohol and then with dilute hydrochloric acid. The serosity is to be carefully evaporated nearly to dryness, when crystals of sodic chloride will form. Pour off the mother liquor, and having evaporated it to dryness, ignite the residue, when a white fusible ash will be obtained. To a trace of this add a drop of nitric acid, and note the evolution of carbonic acid gas ; the rest of the ash is boiled in water and a little carbonate of ammonia added. (a) The jjrecijjitate is collected on a filter, well washed in water, boiled in a little dilute hydrochloric acid, evaporated just to dryness, then dissolved up again in water and filtered. This solution of the precipitate contains jjhosphates and a trace of lime. To part of it a few drops of nitric acid and then excess of ammonia molybdate are added, and on warming gently a bright yellow precipitate of ammonio-molybdic i)hosphate ap- pears. To the rest add excess of oxalate of ammonia and shake well, when oxalate of lime will lie precipitated. (b) The filtrate from the ammonic carbonate precipitate con- tains tiie alkalies, soluble chlorides, su1i)liJites, and pliosphates. (j) To one half add a few drops nitric acid, and then a little DIFFERENT BLOOD COXSTITUENTS. 255 liaric nitrate, when the sulpJuites are jjreoipitated ; to the fil- trate add excess of silver nitrate, which throws down the chlorides ; and to the filtrate therefrom add dilute ammonia to nentralisation, when yellow phosphate of silver makes its appearance. (ij) The other half is to be evaporated to dryness, and the residue gently ignited and subsequently dissolved in water, a few drops hydrochloric acid added, and then evaporated in a capsule ; sodic chloride crystallises out in cubes. Decant the mother liquor, add to it platinic chloride and alcohol, and stir well with a glass rod, when a crystalline yellow precipitate of potassio-platinic chloride will form. 3. Separation of Lecithin, Fats, and Cholesterin from the Coloured Corpuscles. — A clot is expressed through a linen cloth, and tlie fluid that exudes is to be treated with excess of ether and well shaken ; the ether is separated by decantation, and the residue again extracted with more ether. The ethereal extract is then filtered and evaporated ; a crystalline residue is obtained of fats, cholesterin in needles, and lecithin in little tufts. By adding water the lecithin swells up and becomes almost insoluble in ether, so that by treating the residue with the latter solvent after the action of the water the fats and choles- terin are removed. 4. Separation of the Corpuscles. — (a) Let the blood flow from the vein into a saturated solution of sodic sulphate contained in a vessel surrounded by a freezing mixture ; no coagulation will occur, and the corpuscles will settle down to the bottom of the vessel. Pour off the supernatant liquid after two or three hours and collect the sediment on a filter, where it is to be washed with a solution of sodic sulphate. (h) Snip off the apex of a frog's heart and let the blood flow into a solution of sugar {^ per cent.) ; filter rapidly ; the filtrate coagulates immediately. {c) Allow the blood to flow into a ccld and dilute solution of magnesic sulphate (2 per cent.) and of ammonic chloride (2 per cent.) The globules sink and can be collected by filtration. [d) 0ne of the most ingenious methods is to collect some venous blood in a tube surrounded by a freezing mixture, and then subject the tube with its contents to a continuous and 2oG riSSUJSS, OliGANS, AND REMAINING SECHETIONS. very rapid horizontal rotatory motion in a centrifugal machine ; the globules tend to collect at the outer end of the tube (Salet and Dakemberg). (t") Collect some horse's blood in a long narrow thin glass cylinder immersed in a freezing mixture. After a couple of hours remove the fluid from the deposited corpuscles by means of a siphon, and wash the corpuscles with salt solution. 1\\e plasma can also be obtained by any of these methods. 5. Experiments with Plasma. — (a) Place a little in a watch glass and warm gentl}', when a clot forms, owing to the coagu- lation of the plasmin present. (6) Add to another watch glass some of the plasma, and four times its volume of distilled water : a coagulum will form after some time. (c) To a third watch glass add some plasma, then a little mag- nesic sulphate solution (1:4) and about eight parts of water: no coagulation will occur until a little fibrin oplastin is added. 6. Preparation of Fibrinoplastin and Fibrinogen. — (a) Dilute a little serum with ten times its bulk of cold water, and pass a current of carbonic acid gas through it : a granular precipitate of fibrinopla still is obtained, which will settle after some time. Saturation of the serum with sodium chloride produces the same result. (h) Dilute some hydrocele fluid with ten to tw^enty times its volume of water, and by saturating it with sodic chloride in powder, or by passing a current of carbonic acid gas through it for some time, a white slimy precipitate oijibrinofjenis obtained. 7. Preparation of Blood Ferment. — Coagulate fresh ox blood by the addition of 20 volumes of alcohol (85 per cent.), filter, and after eight to twelve days decant and dry the residue over sulphuric acid; then pulverise and digest the powder with dis- tilled water. By reprecipitating the watery solution with alcohol, and drying the precipitate again over sulphuric acid, the fcDnent is ])urified. 8. Preparation of Fibrin Clot. — (a) To a little hydrocele fluid add some serum, and after a short time a clot will form. The hydrocele fluid contains fibrinogen, and the serum fibrino- plastin and ferment. (b) Prepare fibrinogen from dilated liydrocek- fluid by DIFFERENT BLOOD CONSTITUENTS. 207 saturating the latter with sodic chloride, and fibrinoplastin by saturating diluted serum in the same way. Now, after washing the precipitates well with a little water to remove excess of sodic chloride, they will soon dissolve when more water is added ; mix the solutions thus obtained and a clot will form. 9. Detection of Ammonia. — This, as a rule, can only be detected in diseased conditions, particularly in m-semia and certain zymotic diseases. Place the fresh blood in a small beaker and cover with a plate of glass, this being rendered more or less air-tight by smearing the points of contact with lard. On the under sur- face of this slip of glass spread out a few drops of ammonia- free dilute sulphuric acid before it is fixed down. Ivcave the beaker aside for an hour or so in a moderately warm room, and then test the dilute sulphuric acid with a few drops of Nessler's solution, when ammonia will be shown by the yellow coloration. Nessler's solution is thus prepared : 35 grams potassic iodide and 13 grams mercuric chloride are added to 800 c.c. of water, and the mixture boiled with frequent stirring until the salts dissolve. Then a cold saturated solution of mercuric chloride in water is carefully added until the red mercuric iodide formed just begins to remain undissolved. ^Ve have now a solution of potassic iodide saturated with mercuric iodide. This is rendered alkaline and sensitive by the addition of 160 grams caustic soda, and the whole diluted up to 1 litre. A little more mercuric chloride must be added, and the mixture laid aside to settle. The reagent should have a yellow tint. CHAPTEK VIII. TESTS AND rUARACTERISTICS OF BLOOD. I. Chemical Tests for Blood. 1. Immerse a piece of linen rag in blood and dry it. Leave a cutting of this for a couple of hours in cold water, and a dingy red solution will be obtained, some of the colouring matter also gradually collecting at the bottom of the vessel. ■2oS TISSUES, OEOANS, AND REMAINING SECRETIONS. 2. Boil a little of the solution thus obtained, and a dirty red eoaguluui will form. Decant the fluid, and having added to it a little caustic potash, boil, and a solution will be obtained which will be red by reflected and green by trans- rnitted light. 3. Add a few drops of nitric acid to a little of the coloured solution, and a brown coagulum will appear. 4. Boil a shp of the stained rag in water to which some tannic acid has been added, and it will become black or grey coloured. 5. Boil another slip with dilute hydrochloric acid, and add a few drops of potassic ferrocyanide : a blue precipitate appears, indicating iron. 6. Add to a little blood twice its volume of caustic soda (sp. gr. 1*3), and a flocculent greenish brown precipitate is obtained, which gradually dissolves ; if now a small stoppered bottle is filled with the solution and laid aside, it will after a time assume a violet colour. II. Practical Exercises with the Spectroscope. 1. Oxyhcemoglobin. — Examine a dilute solution of blood or haemoglobin about two-fifths of an inch thick spectroscopically, and the two bands between D and E will be seen ; note that the band near D is narrower, darker, and better defined than the other. 2. Spectroscopic Examination of the Girculating Blood. — Bring two of the fingers together in front of a bright light in such a way as to allow a faint rosy light to pass through; examine this last with a spectroscope, and the two absorption bands of arterial blood will be seen. Then apply an elastic ligature to the two fingers, and on examining as before it will soon be noticed that instead of the two absorption bands of oxy- hcemoglobin the single band of reduced haemoglobin makes its appearance. 3. Reduced Hoiriioglobin. — Add to a little blood or haemo- globin solution some reducing agent, as ammonic sulphide, protochloride of tin, or the ferrous sulphate mixture (p. 241). Examine rapidly, and a single broad band occupying about three-fourths of the space between D and E will be seen. TESTS AND GHAMACTERISTICS OF BLOOD. 259 4. Hccmatin. (a) Alkaline Hccmatin. — Add a little ammonia or caustic potash to a solution of blood or haemoglobin ; a broad band appears between c and d, but ueai'er d ; with concentrated solutions, say of baric hydrate, the band extends more on each side, reaching on the blue side nearly halfway between d and E. (73) Acid Hoematin. — Add some drops of acetic acid to the small tube or vessel containing a moderately concentrated solution of blood or haemoglobin. Sometimes it is advantageous to add in addition a volume of ether equal to that of blood. On examination several bands are to be seen, but one distinct black band in the red is to be looked for, almost coinciding with the line c, and extending somewhat on each side. The position and character of this band vary more or less according to the acid employed. Preyer, indeed, partly for this reason divides these acids into four groups. With formic acid, for example, the band lies a little more to the right than with acetic or phosphoric acid, and with oxalic acid still further ; but the strength of the acid also causes a variation. (7) Reduced Hcematin. — Treat the solution of acid haematin used in the previous reaction with a ferrous salt, and two new bands appear, one beginning near D and extending halfway between D and E, and the other stretching on each side of e. III. Detection of Blood in Spots, Stains, &c. A. By the Microscope. — If the blood is still liquid place a drop of it on a slide under a thin cover glass, and if it cannot be examined at once surround the margin of the cover glass with a little melted parafhn or wax. Note the shape and diameter of the corpuscles, and whether nucleated or not. If the blood spot is dry it must be softened with iodised serum (prepared by adding tincture of iodine to amniotic fluid until the latter acquires a faint yellow tint, or to an artificial serum consisting of water 270, sodic chloride 0'4, and albumin 30), or with sodic chloride solution (three-fourths per cent.), or sodic sulphate solution (one-half per cent.), or saturated watery solution of arsenious acid. Eecent blood stains are bright red, older stains of a reddish brown. With recent stains softening 203 TIS>>UES, ORGANS, AND REMAINING SECRETIONS. occurs rapidly, but an old spot may require days. By means of a capillary tube some of the coloured fluid is to be transferred j as before, to a slide and examined. Thin threads of fibrin may be seen, and by the addition of acetic acids these are rendered more distinct, on account of their swelling up and assuming a gelatinous aspect. As it is very importmit to discover the presence of the cor- jjiiscles, an effort should always he 'made to find them. B. By Chemical Examination. — To obtain a solution of the blood, especially if it is in the form of an old dry stain, it may be necessary, in case the blood is not removed by soaking the stain in water, to seal up the piece of stained rag in a stout glass tube containing a little water; this tube is then suspended for an hour in oil at a temperature of about 150°. A solution of arsenious acid serves well as a blood solvent, also a watery solution of borax. When blood is diluted with water it may be precipitated with acetate of zinc, by which means it may be detected even in dilute solutions. {a) The Guaiacum Test. — Add to a solution of the blood some tincture of guaiacum and a little ozonised ether ; the former should be freshly prepared (p. 241), and the ozonised ether can be made by adding oxygenated water to pure sul- phuric ether. The test may also be thus applied : Moisten the spot with water and cover it with several folds of white blotting-paper that gives no reaction with the guaiacum. Now press the paper very firmly down upon the suspected spot ; if blood is present the paper will generally acquire a yellowish red or brownish stain. Cut this stain into two or three strips ; treat one with ammonia, and note if a scarlet or greenish tint is obtained ; moisten another strip with spirits of turpentine that has been exposed to the air, and add a drop of the tincture of guaiacum, and to the third slip some drops of the guaiacum tincture and ozonised ether. Note if a pale or indigo blue appears in a few minutes in the last two slips. The presence of nasal mucus, saliva, and pus interferes with this test. (6) The stained i)arts are to be scraped, washed, &c., and a solution prepared with as little water or borax solution as possible. TESTS AND CHARACTERISTICS OF BLOOD. 2G1 (j) Drops of this solution are then to be placed on watch glasses or on slides, and to be tested in turn with drops of the following solutions : nitric acid, acetic acid and ferrocyanide of potassium, and tincture of nut gall. All these reagents effect a precipitation, and the whitish flocculent opalescence produced is easily recognised under the microscope. (ij) To a little of tlie solution add a drop of ammonia: the red colour of blood is not altered ; vegetable reds, however, become blue. (iij) Dissolve a little of the stain or clot in boiling caustic potash : the stain loses its colour and the solution obtained will appear reddish by reflected and greenish by transmitted light, and will give a precipitate with nitric acid. (iv) To a little of the filtered solution add tungstate of soda solution strongly acidulated with acetic acid, and a reddish brown precipitate appears. If this precipitate is dissolved in ammonia a reddish green dichroic solution is obtained. C. By the Spectroscope. — This method requires considerable care, and although it is very characteristic the results are not always easy to obtain unless the blood is sufficient in quantity. It is also advisable to use a spectroscope with a scale, and to note the exact position of the bands. Both the oxyhaemo- globin bands are seen faintly with -^-^t^i per cent, solutions of haemoglobin (Preyer). The solution, if too dilute, may be evaporated on a watch glass and the dry residue examined. This same dry residue can then be used for the preparation of hgemin crystals, as in D. (a) The spots or stains are scraped off and digested in water to which a little ammonia has been added. The solution so obtained is to be ' examined ' spectroscopically in as thick a layer as possible, and the absorption bands of oxy haemoglobin looked for. If the two bands are visible then add two or three drops of ammonic sulphide, and in a few minutes the single band of reduced haemoglobin will appear ; shake this last solution for some time in the air, and the two bands will reappear. (6) If the hai'moglobin bands cannot be found satisfactorily, try for the absorption bands of hamatin. Mix the ammoniacal solution with glacial acetic acid till it is markedly acid, and transfer it to a small stoppered bottle ; add its own volume of 262 TISSUJES, OltGANS, AND REMAINING SECRET IONS. ether, and shake well for a short time. If the ether does not separate readily, add glacial acetic acid drop by drop until the precipitate that appears is deposited or redissolved. The ether then separates with a reddish brown colour. This coloured ethereal solution is next poured into a small glass vessel with parallel walls, and examined with the spectroscope ; if not too dilute the acid haematin bands will be seen, particularly the sharply defined band in the red (over c) and a less intense band in the green. (c) Treat a portion of the spot with a few c.c. of a cold satu- rated solution of borax at 40°, and examine spectroscopically. A somewhat similar spectrum may be obtained with cochineal solution, purpmin-sulphonic acid, &c, ; but the cochineal is de- colom'ised by chlorine water without yielding a precipitate ; and the haemoglobin, when reduced with sodic sulj^hide (1 : 5), gives the single band of reduced haemoglobin. (d) Dilute a portion of the solution with five to six volumes of water, and precipitate it with acetate of zinc solution (5 per cent.) Dissolve the washed precipitate in 1 to 2 c.c. glacial acetic acid, and examine spectroscopically for haematin, part of the precipitate also being tested as in d for haemin crystals. D. By the Formation and Detection of Crystals ofHcemin. — The blood spots or scrapings are treated with warm glacial acetic acid, and to the solution a few grains sodic chloride are added ; heat over a spirit lamp for some time, fresh acid being added if necessary. It is advisable to repeat the addition of the acetic acid several times and to heat after each addition, and the formation of the crystals occasionally seems to be facilitated by moistening the residue after each evaporation of the acetic acid with a few drops of water, and evaporating this in turn before the next addition of acetic acid. Finally, the whole may be evaporated over a water bath. The entire operation can be satisfactorily performed upon a glass slide (p. 249), and the preparation examined micro- scopically after the addition of a few more drops of acetic acid and the application of a cover glass. With a high power dark brown rhombic crystals, often arranged in stellate groups, make their a]>pearance. E. In cases where the amount of blood is very small, not TESTS AND CHAIiACTERISTICS OF BLOOD. 2G3 rtiore than a drop or a stain, proceed as follows, as the same specimen serves for each successive test (Hoppe Seylek) : — 1 . Remove the spot or stain of blood. 2. Macerate it in a little water contained in a watch glass. 3. If no proper solution occurs, but merely a separation of the colouring substance, dry as completely as possible over sul- phuric acid, so that a coloured layer may be deposited. 4. Apply the spectroscopic test to this deposit. 5. Then try to produce hsemin crystals by adding a little sodic chloride and ten to twenty drops of glacial acetic acid, stirring well with a glass rod ; when all is dissolved evaporate rapidly over a spirit lamp and complete the evaporation upon a water bath. When the odour of acetic acid is no longer per- ceptible examine with a high power. Instead of acetic acid alone a mixture of chloroform (6) and glacial acetic acid (1) may be used with advantage (Selmi). 6. Now wash the contents of the watch glass with a little water, and throw upon a small filter ; hsemin is insoluble and will remain on the filter ; treat it here with a few drops of caustic soda, when a greenish or red liquid will be obtained, according to the thickness of the layer. Evaporate this to dryness in a porcelain crucible, calcine the residue, and dissolve the ash in a little pure hydrochloric acid ; then evaporate the excess of acid, add a few drops of water, and test for iron by means of ferrocyanide of potassium and potassic sulphocyanide. CHAPTER IX. ESTIMATION OF SINGLE CONSTITUENTS OF BLOOD. In many of the following weighings it is best to allow the blood or serum to flow into a weighed capsule, and by a subsequent weighing of this, when covered, ascertain the increase of weight. 1 . "Water and Ash. — Twenty-five grams of serum, blood, or defibrin- ated blood are dried in a platinum crucible over a water bath, followed by a hot air bath at 110° to 120°. The loss in w^eight is due to the water, but the w^eighing should be repeated several times till a nearly 2Gi TISSUJES, OJiGANS, AND REMAINING SECRETIONS. uniform result has been obtained after repeated heatings. The crucible is next cautiously heated in a tilted position over a Bunsen lamp, and the temperature gradually increased until the ash is of a reddish white colour. The heat must not be more than a feeble red heat ; and it aids the combustion if nfter the water has been ascertained the dried mass is removed and finely powdered before being iguited. 2. The Soluble and Insoluble Salts and Chlorides.— (r^) The ignited mass, after it has been weighed, is to be repeatedly digested with water and then filtered. The insoluble residue, after having been dried, is again ignited until the cai'bon is completely burned. The weight of the residue is equal to the weight of the insoluble salts. {h) The filtrate contains the salts soluble in water. Evaporate it to diyness in a weighed platinum crucible, heat to a dull redness, and weigh : this gives the soluble salts. (c) This last residue is dissolved again in water, acidified with nitric acid, and the chlorides precipitated with silver nitrate; the beaker containing the mixture is next to be covei^ed with a small box or otherwise protected from the light. When the precipitate has completely settled, the supernatant liquid is tested with a drop or two of the silver nitrate to ascertain if the chlorides are entirely precipitated. If this is the case, collect the silver chloride on a filter whose proportion of ash is known, wash it here with water containing nitric acid and then with pure boiling water ; next dry at 100°, and melt the separated precipitate in a porcelain crucible; now let it stand aside and cool ; the filter is then cut into little pieces and placed inside the crucible cover, and when it has been carefully calcined add the ash to the silver chloride in the crucible. This is to be covered, gently heated, allowed to cool over sulphuric acid, and weighed. Example. — Twenty-five grams defil)rinated blood dried and carbonised. After the extraction of the soluble salts and the com- plete combustion of the cai-bon the insoluble salts weighed 0'022 gi\am. The watery solution evaporated in a platinum capsule and heated to faint redness gave 0-173 gram residue = the soluble salts. The solution of the residue in water, acidulated with nitric acid and precipitated by silver nitrate, gave the following : — Grams PorceLiin crucible with silver clilnridf ;mrl nsli nf filter . 21-176 „ , 24-2;51 0-21.5 Ash of tutor 0-002 Silver clilorido 0-243 ESTIMATION OF SINGLE CONSTITUENTS OF BLOOD. 205 Ag = 108 ^^ ^ ^'--'^ . 35-5 X 0-243 ,. ^rn r-i U3-5 = 35-5 CI : therefore — ---— — = OOGO CI. 143'o Calculating the percentages in the blood from these results, wo obtain — Gram Insoluble salts . . . 0-086 Soluble salts . . . 0-678 Total salts .... 0-764 Chlorine .... 0235 (GORUP Besanez) 3. Fibrin. — Twenty to thii-ty c.c. of blood collected directly from a vein ai-e well stirred for ten minutes or so with an ivory or whalebone spoon in a previously weighed caoutchouc- covered bottle, the spoon passing through a slit in the caoutchouc; weigh again ; and after it has stood some time remove the cover and wash the resulting fibrin with a little dilute sodic chloride solution. The fibrin is then collected on a tared filter and washed with dilute sodic chloride solution and then with pure water ; it is subsequently transferred to a dish and washed there successively with water, alcohol, and ether, and after being dried at 110° it is weighed between clipped watch glasses. 4. Fats. — Ten grams defibrinated blood or serum are dried over a water bath and then in a hot chamber at 120° ; the mass is pulver- ised, and is next digested repeatedly with ether, and the ethereal solution evaporated. A yellow semisolid fat is left behind : weigh this ; then treat with cold alcohol, when a crystalline fat will be removed and an oily fat left behind. This latter may be weighed after evaporating off the alcohol. 5. Albumins, &c. (a) By Heat Coagulation. — Five grams of blood or serum are diluted with 25 grams of water, then acidulated with dilute acetic acid and boiled. The coagulum is collected on a previously dried and weighed filter and well washed there with water, alcohol, and ether, di-ied at 110°, and weighed. The coagulation may be produced by boiling 20 grams of water in a large porcelain capsule, and then adding to this the diluted blood or sei-um ; a little acetic acid is subsequently added, and the boiling continued until the albumin has separated completely. If the liquid from which the coagulum has been separated, together with the washings of the latter, is evaporated to dryness over a water bath and then at 110° for some time, and weighed, we obtain the extractives and salts. Calcine completely, let cool, and weigh again : 2G6 TISSUHS, ORGANS, AND REMAINING SECRETIONS. the loss in weight corresponds to the extractives, while the difference is the weight of the soluble salts. (6) 1^1/ Alcoholic Precipitation. — To 20 or 30 grams of the blood or serum neutralised with dilute acetic acid add 10 volumes absolute alcohol, lay aside for a few days; next collect the precipitate on a weighed filter, and after washing it with dilate spirit, absolute alcohol, ether, and hot and cold water in succession, dry it at 110° ; now weigh it when it has been cooled over sulphuric acid. If accurate results are required the coagulum should be calcined and the weight of the ash obtained subtracted. (c) The polariscope can also be employed in the determination (see under Urine, p. 508). 6. The Corpuscles. — («) Defibrinated blood is mixed with three times its volume of saturated solution of sodic sulphate, laid aside for 24 hours, and then filtered. The corpuscles remaining on the filter are then plunged into boiling concentrated solution of sodic sulphate, and afterwards washed in distilled water, dried, and weighed. In- stead of filtering we can decant, and after washing the deposit with the sodic sulphate by decantation we add to it four times its volume of alcohol, Avhich renders it insoluble. After some time the alcohol is decanted ofi', the deposit washed again, dried, and weighed : the weight will be the haemoglobin + the albuminoids of the corpuscles. (b) Another phin for the estimation of the corpuscles is bi/ enumera- tion. A known volume of blood is diluted 100 times or so with a neutral fluid ; of this a minute quantity is taken, and the corpuscles in it counted. (1) Malassez' ^;^rt'/i is the following : The finger is pricked and the blood sucked up into a fine graduated capillaiy tube provided with a dilatation near its upper end ; above and below the dilatation is a mark : by drawing the blood up as far as the lower mark, and then drawing up the artificial serum till the upper mark is reached, we have a mixture containing 1 per cent, of blood. The two fluids are mixed in the dilatation, which contains a small glass bead to facilitate the intermixture. A 10 per cent, solution of sodic sulphate may be used as the artificial serum, or a solution tlius prepared : solution of gum Arabic (sp. gi\ 1020) one part, and a solution of equal parts of .scdic sulphate and sodium chloride having a sp. gr. of 1020 three parts. The l>lood thus diluted is next introduced into a gradu- ated flattened capillary tube, and a portion of this is examined with a high power, the eye-piece of the microscope being provided with a micrometer divided into .square millimetres. The process of enumera- ESTIMATION OF SINGLE CONSTITUENTS OF BLOOD. 207 tioa must next be proceeded with ; and, knowing tlie lengtli of the tube covered by the squares, a little calculation will determine the corpuscles present in a cubic millimetre. (2) Haye-m's methotl as modified hjj Dr. Gowers is effected with the following parts : a small pipette fitted with an elastic tube holding up to a mark on its stem 995 cubic mm., a capillary tube marked to contain 5 cubic mm., a glass mixing jar and stirrer, and a brass stage plate provided -with a glass slide on which is a cell 1 mm, deep and whose base is divided into j'^ mm. squares. The mixing fluid consists of a solution of sodic sulphate of about sp. gr. 102.5 ; 995 c.mm. of this are placed in the mixing jar, and 5 c.mm. of blood fresh drawn from a puncture in the finger are transferred by means of the graduated capillaiy tube to the same. The fluids are well mixed, and a small drop is transferred to the centre of the cell on the glass slide. This is covered, and the slide placed on the stage of the microscope. The corpuscles soon sink ; the number in 10 squares is then counted, and this being multiplied by 10,000 gives the number of corpuscles in a c.mm. of blood. The blood of the capillaries contains o\ millions in each c.mm. (cubic millimetre), and about 1 pale coi'puscle to every 350 or 500 coloured corpuscles — a proportion, however, which is greatly increased in certain diseases, and normally after food. 7. Urea. — 100 grams defibrinated blood are placed on a dialyser that floats in about 100 c.c. to 200 c.c. of absolute alcohol. In a few hours the fluids of the blood holding the urea in solution will have dialysed out into the alcohol. The contents of the dialyser, which solidify after a time, are mixed with a little water and the process repeated, so as to extract all the urea present. Some oxalic acid is then added to the alcohol, and this is evaporated to dryness on a porcelain dish. Crystals of oxalate of urea, with some fat, colouring matter, and sodium chloride, are present in the residue ; and by treating the latter a\ ith petroleum naphtha the oxalate of urea is left behind, and it is to be dissolved in water, mixed with baric carbonate, and evaporated to dryness ; or the urea can be extracted by ethyl acetate after the i-e- moval of the light petroleum (Haycraft). If the latter plan is not adopted, then boil the dry residue with alcohol, and on evaporating the alcoholic solution pure crystals of urea are obtained, the amount of which can be determined by weighing, by decomposition with sodic hypobromite after the addition of a little sugar, or by Simpson's method (see Urea). 8. Uric Acid. — This determination is rarely required except in cases of gout or rheumatism. The serum (about 20 c.c.) is dried, and the 268 TISSUES, ORGAXS, AND REMAINIXG SECRETIOXS. residue rubbed up with hot alcohol. After standing some time the alcohol is decanted, and the residue digested with distilled watei' and then boiled, the M-atery solution being filtered and evaporated to a syrupy consistence. This syrupy fluid, if allowed to evaporate spon- taneously, "will soon show on its surface small white tufts of acicular crystals of urate of soda. A few drops of the solution will also give the murexid test (p. 4-52) ; or if acidulated with acetic acid and allowed to evaporate, crystals of uric acid will form in abundance. A rapid modification of the same process is to place 2 drachms of the serum in a large watch glass, acidulate with acetic acid, and after inserting a linen thread in the fluid set it aside to evapo- rate, and uric acid crystals will soon be formed along the thread (Garhod). 9. Sugar. — («) Dilute the serum with 5 times its volume of water, add dilute acetic acid, boil, and filter. The concentrated filtrate is then tested for sugar with Fehling's solution (Mering). {h) To separate the albumin more completely it will be found advantageous to put the serum into a small capsule, and having added to it an equal bulk of coarsely powdered sodic sulphate crystals, to boil for some time; then filter, wash the px-ecipitate, and test the filtrate with Fehling's solution. (c) Put the weighed blood into a mortar and rub it up with suffi- cient animal charcoal to form a dry paste ; then mix it Avitli a little water and filter, washing the mass on the filter thoroughly with water. The filtrate contains the sugar. {d) Precipitate the blood with strong spirit and cover the coagulum with 4 times its volume of absolute alcohol ; filter after 4 or 5 days ; decant the spirit and distil it ; extract the residue with more alcohol, and evaporate again. Now test a solution of the dry residue for sugar by the fermentation process, (e) 40 grams sodic sulphate in small crystals are placed in a beaker, 20 c.c. blood added, and the beaker and its contents weighed. Stir the blood and crystals together, pour 30 c.c. of a hot concentrated solution of sodic sulphate over the mixture, and boil for some time. Komove the small coagulum, wash it thoroughly in more of the sodic sulphate solution, and add the washings to the contents of the beaker, which are then to be boiled and filtered. The filtrate is to be again rapidly boiled with excess of potassio-tartrate of copper (20 to 30 c.c. Fehling's solution). Now filter thi-ough glass wool, and the suboxide having been collected and washed with distilled water, dissolve it in a little nitric acid after the addition of a few drops of hydric peroxide. Tho dissolved copper has next to be electrolytically deposited on a ESTIMATION OF SINGLE CONSTITUENTS OF BLOOD. 20U }»latiiium spiral, the galvanic action requiring to be steadily and con- tiuuou.sly maintained lor at least twenty-four hours. The increase in weight of the spiral, afcer it has been washed in water and sjnrit and subsequently (.Iricd over a water batli, multiplied by 0'5678 gives the amount of glucose (Pavy). CHAPTEK X. PATHOLOGY OF THE BLOOD. I. Types of Pathological Variations (Gautiek). 1. In aniemia and chlorosis, and in all chronic maladies generally, as a consequence also of hsemorrhages, we find the corpuscles andfihrln diminished and the luatev increased. 2. In the invasion of iutermittents, in the decline of the exanthemata (variola, scarlatina, &c.), in the early stages of phthisis, in typhoid conditions, in Bright's disease, and in some cases of chlorosis, the corpuscles are diminished, the jlbrin normal or slightly increased, and the ivater increased. 3. In plethora, in the invasion of the exanthemata, in the reaction period of intermittents, the corpuscles are increased, the fibrin normal or slightly diminished, and the ivater diminished. The water is also diminished in continued fever, diarrhoea, and cholera. 4. In the early period of inflammatory fevers, as pneumonia, pleurisy, erysipelas, and rheumatism, the corpuscles are normal or diminished, the fibrin increased, and the ivater norinal. Later in these diseases the corpuscles fall below the normal. 5. When in tlie course of a chronic affection an inflamma- tion is lighted up, as in the last stage of phthisis or in typhoid fever, then the corpuscles are diminished and the water and fibrin increased. II. The Blood under Pathological Conditions {after Gorup Besanez). (See table, p. 271.) The oxy(jen of the blood increases in inflamed conditions, and we generally find a greater proportion than the normal both of oxygen 270 TISSUJES, OliGAI^S, A^W REMAINIXG SECRETIONS. and carbonic acid in the blood coming away from an inflamed oi-gan or tissue. In septiccvmin the coloured corpuscles are much altered, their specific gravity being lessened, and some loss occurring both in their salts and haemoglobin. There is an increase in the pale corpuscles, the fats, urea, and carbonic acid, and an abundance of free gi'anules, bacteria also at times making their appearance, as well as an occa- sional excess of lactic acid and ammonic carbonate ; and a diminution in the amount of fibrin and albumin, the latter body also appearing to be altered in quality ; further, less oxygen and glucose are said to be present. In chlorosis the number of the coloured corpuscles is lessened ; their si^e likewise is said to diminish slightly, as also the proportion of ii"on and haemoglobin present in them. In this disease, as well as in leukaemia, pyaemia, and puerperal fever, the pale corpuscles are gieatly increased ; and a similar increase may be noted in some cases of tubercle and pneumonia. The proportion of albumin is increased in chyluria, intermittent fever, cholera, in the early stages of typhus, and after drastic pur- gatives, but diminished in most diseases in which the fibrin is increased, particularly where much exudation occurs. The fats increase when the circulation is interfered with ; also in pneumonia, chronic alcoholism, diabetes, and in some cases of acute and chronic poisoning. While normal blood furnishes from O'l to 0'4 per cent, of dry fih'in, the proportion has been found as high as 1 to 1 -2 per cent, in acute erysipelas, and from 0*.5 to 1 per cent, in acute pneumonia. An increase occurs in the early stages of typhus, dysentery, puerjDeral fever, chlorosis, scurvy, and Bright's disease ; in hydisemia it is diminished. Leucin and tyrosin make their appearance in the blood in most cases of yellow atrophy of the liver, III. Alterations produced by Certain Toxic and other Agents, Heemorrhage, &c. The pro[)ortion of sufjar is frequently increased after poisoning with chloroform, chloral, curara, nitro-benzol, and amyl nitrite. In lead poisoning the corpuscles are diminished in number, but their individual volume is said to be increased. Antimonvd coiirpounds act rapidly on the blood, increasing its fat and cholesterin, and apparently diminishing its gases, and giving it an anajmic character. Under the use of arsenic the fat and cliolesterin PATHOLOGY OF THE BLOOD. 271 -2 -s til 1 •a "3 '& a •3 g? = p i OQ s ^i-a 1 X4 .S .S ^ .5 m •" s •-" _ TZ 'T'O ■C ■a ri 2 w O o o S 1 1 2S 'i 1 1 o o o o a a .9.2 a a e5 .^ .« .« 'a xa S<=> a , a •5-| 4^ be 1 1 -1 8 1 I II II I I cs c3 ■Xt 9 o a. — ^>f^ a 1 ci 13 -a CI -J -a i" IS S o i: a m \ \ 1 m It 1 1 1 1 S S P ' = «7 =. % § ' 1 ' S 11 II 1 ' IS cS +j o o Q -t ^ ^ 1 u u .S 1"" "" a a a "^ ""* ■3 ■a O 01 o T' ^ 1 I 1 2 c; I -3 > ! 1 1 1 1 1 i 1 1 " 1 o 1 1 X w 11 ' ' ^ o P4 .9 •o ■c -^■a •a 13 •a s 1 J3 % % 1 S.S 1 M "•2 -SI 1 1 1 i 1 1 1 .52 .2 1 1 1 a 1 a 1 1= 1 1 ^ 5 o S S 2 o a o'a b s .a --o £3 .r^ J2 .a "^ raha •SS m ■;! -C n -c -a-c o M g -c-c S o „ -3 -a •a o £ o 0,^0 o o -a 2 S Ooc3 '^SJ'S <^" CO 1 '5 ' 'c .1 1 s 1 a 11 1 1 „ii 1 Pi I ■§ 5..3 o o a -2 p, % .3.3^ a 2 a ill 3 3 1 o S .3 s ^S "3 .3S -a "C 13 .3 1 1 1 III 1 1 1 II Ml 1 :3 1 i :s cS -a ii 1 1 '& S 3 S a S 3 a 1 a o o g .S -5 "3 .3.5 a a , - - c>>-a a « S « .3 to fe S-S 1,3 ,11 ^1 A ■3 +3 C8 I-s-3 I 1 s>. Ml 1 ira 1 1 CJ a « 1 ( ^ i.§ 1 a is jsi i Is o .S •'3 .3.3 « ^ ^.3 i _S a == ■" o ^ ^"3 S^-g & ^ 5 c ~ < • i 1 1,^ 3 3 o m|i i 1 5 a ! 1 :23ia§g|gSiJ S.h 1 1 1 o^l io a 1 ' ° .2 3 3 A u ■ £ S.a ^3 S — =« . o . . 5: '& 1 ' 1 ia'a > l§=s i = cj - • 3 R i 1 liilll C w U O C S Sc a c «4-l o 27-2 TISSUES, ORGANS, AND HEM A IKING SECRETIONS. increase ; and in cases of antimonial as well as arsenical poisonings the biliary acids have been noticed to be increased. Under the influence of phosphon's the fat, cholesterin, and fibrin increase, the albumin diminishes, and the corpuscles are altered, the hfemoglobin occasionally appearing to become crystalline in theii' in- terior. Quinine and alcohol are said to increase the volume of the cor- puscles, while morphine and carbonic acid produce the inverse effect (Manassein). Bile or the biliary acids injected into the vessels cause a crystallis- ation of the haemoglobin, the corpuscles undergoing much alteration, the blood being rendered anjemic and its fat and cholesterin increased. In many cases of jaundice it is possible that somewhat similar I'csults are gradually induced. Sulphuretted hydrogen ven^ev^ the blood brown and then greenish in tint ; carbonic oxide gives it a cherry I'cd, chlorine gas a greenish yellow, and arseniuretted hydrogen a brownish ochre coloration — phosphuretted and antimonetted hydrogen having a similar but weaker action than this last gas. Under the influence of nitrous oxide there is a tendency to a displacement of the oxygen of the corpuscles, the exhalation of the carbonic acid at the same time being diminished ; the blood has at first a dark tint, but it afterwards assumes a bright red colour ; there is further an increased excretion of water, urea, and uric acid by the kidneys. In animals poisoned by nitrites, as nitrite of amyl, the blood is of a chocolate colour, with abundance of methsemoglobin ( Hoppe Seyler). As the result of hcemorrhages the corpuscles diminish in number, but the fibrin appears to increase (Delafond), although some maintain the contrary. Bleeding increases the water and lessens the oxygen, but it affects slightly or not at all the proportion of albumin and salts. The blood, however, rapidly recovers its normal condition. In dogs that were allowed to eat freely after blood-letting it was found that while the proportions of the inorganic constituents of the scrum remained constant the organic solids diminished suddenly and continued to diminish for several hours ; after which time they began to increase, and continued to do so till, after 14 days, they exceeded the normal quantity. AVhen, on the other hand, the dog was kept without food, it was found that the solid substances of the serum, which hud diminished immediately after the blood-letting, began to increase .sooner than in the former case, so as to exceed the normal amount after two days. In this experiment it was noticed that when food was given to the animal the proportion of solids in the serum immediately diminished. rATIIOLOGY OF THE BLOOD. ^73 Different un/ani.wis are occasioiinlly to be met with in patboIo;,ncal blood. In tuberculosis, for exami)le, bacilli are present in great numbers, and appear to be the cause of the disease. They may be detected in the sei'um by a mixture of alkaline methylene blue and vesuvine, whereby they alone are coloured blue (Koch, Baumgarten, Toussaint). CHAPTER XI. LYMPH AND CHYLE. The lymph carries into the blood the products of the fanc- tional activity of the lymphatic glands, as well as of the retrogressive metamorj^hosis of the different tissues of the body. While the chyle is the assimilable extract of the chyme, the lymph may be regarded in great part as the overflow of the interstitial fluid which is constantly being renewed and modified by the blood. While an animal is fasting its chyle is clear and transparent, and the same can be said for the lymph in the thoracic duct ; indeed, the contents of the lacteals and lymphatics may be said t(» be identical until after a meal, when the fluid in the lacteals and in the duct becomes milky in appearance, owing to its being charged with fatty particles. I. LYMPH. Amount. — It is very difficult to form a correct estimate of the total amount of lymph and of the interstitial fluids of the body. All the constituent parts of the tissues and organs are, we know, bathed, as it were, in an interstitial fluid, which, together with the contents of the lymphatic vessels in direct continuity with the interstitial spaces containing this fluid, has been estimated as high as one-third to one-fourth the weight of the body. Of chyle and lymph it is reckoned that for every 220 lbs. of body weight about 13^ lbs.- — that is, a quantity of fluid equal to the whole blood— pass through the thoracic duct in the twenty- four hours, about 7^ lbs. being chyle from the intestine and 6 lbs. lymph from the tissues (Schmidt). Physical Properties. — Lymph is a transparent, whitish, opalescent, or even yellowish or faintly reddish, slightly viscid T 274 riSSUHS, ORGANS, AND REMAINING SECRETIONS. fluid, that is less alkaline than blood, and having a density of 1022 to 1037, or occasionally as high as 1045 (Krimer). When removed from the body, lymph coagulates in five to twenty minutes. It consists of plasma and corpuscles. The latter are identical with the pale corpuscles of the blood, and aie chieflv derived from the lymphatic glands, from which the lymph is constantly can-ying these bodies in great numbers into the blood. At certain jjoints of its course the lymph also contains small fatty granules like those of chyle, and colom-ed corpuscles are occasionally met with. Chemical Composition. — Lymph is very variable in com- position. It may be stated generally to be — Water . . 93 to 98 per cent. Solids . . 6 „ 2 >j Albumin . . 3-2 to 0-3 ,, Fat . Extractives . 0-1 f" ^^^ )) Ash . . 0-7 „ 0-8 „ The solids average aljout 4 to 4"6 per cent., and the sodic chloride about 0-6 per cent. (Nasse). Human Lijmph, SjC. (0 jnf,Eii and (Hrvskv and (Schmidt) QUEVEXNE) DAUXHARUT) Water 96-39 93-48 98-52 Solids :^-6 6-52 1-48 Fibrin — 0-6 Globulin svibstances and,^ \ serum albumin . 4-28 Fats, cholesterin, lecilhin - 2-9 0-91 r 0-68 Extractives .... 0-43 Sugar ^ 0-05 i Salts — 0-82 0-79 Sodic cliloridc . . . 0-54 Soda 015 Ash of Human Lymph (Dahnhardt, in 100 parts of Ash). Sodic chloride . 74-84 Soda ] 0-35 J'ptasli . 3-22 Lime 0-93 Magnesia 0'2(i Phospbe.sanez). qsjfo snoocooinqoa: (xaiKHDs) xiiff ou3:nras-C(i 95-86 4-14 l-5o 1-4G 1-18 (j.cnwH.'is) iintli-'S 96-97 3-03 0-16 2-01 0-8G 0-26 0-20 0-06 0-06 0-05 (sramiH) sni'BqdoDo.ip ' q ojuo.iqy 98-77 1-23 0-25 0-76 0-08 0-40 0-03 0-09 (j.aimios) snicqdooo.tpXq a^noy «> c^ '.^ a-. iM -* 1 o o CO i-H O O O O ' O O (NJtJ.gavTCWYH) opooapjlH 00 »0 m ^ O fM —4 :/j .-H u5 o -^t* c^ 1 '^ 1 1 1 TO i o -^ 6 o 1 o 1 i 1 uoisnga otquiidid oiuo.iqo 93-50 6-50 - 6-06 0-86 uoistiga oi^i.moxd ajnoy 93-13 6-87 0-81 0-08 5-50 0-81 (zaxrs3a m 'Jl O CM r-l o 1 1 1 1 1 CiaooA) pjnp oppsy 9^-60 5-40 3-30 0-13 0-80 jaqsnq JO ppij t z I ! i 1 1 1 ! 1 Ci , ■ (Hoaai) sjBax 98-20 1-80 0-50 1-32 0-30 (naAawHoi) 0;fa JO anouinq snoaJiiA. 98-64 1-36 0-02 0-13 0-32 0-88 0-06 0-77 0-01 0-02 CHaASiivitoq) i\v:> ^o o.C;j JO -inomnq suoonby 98-69 1-31 0-12 0-42 0-07 001 0-69 0-02 0-04 A\00— (iMSAVHfVJV) ping oio^iiBdv 08-85 1-34 1-24 0-8" 0-09' 0-03 (Ml.V.ttOllOOJId) pitqj oijoiu-iiy 98-14 1-86 0-52 0-77 -0-52 004 upyiq ■Buids jo pinij; 98-99 1-01 04 0-14 0-81 (z).-! 05J VHJI5IH0RI.H0S) Ping iBujds-ciqD-iao 1 1 1 1 1 1 1 f 1 1 1 snd JO innjocj 1- TO <•' TO 1~ TO » '.- CS t^ 1 1 1 , 1 ^ CO t; o 6 1 1 1 1 1 iiituas poooia (JXIIWHOS) UOJBBlfl pOOia % I \ I i I \ 1 1 1 1 ..-5 I.-5 o 2 CO CD O CO 1- 0< «coco T* co«'rtPC^ cV 6 6 g g g 1 i 1 Water . SoUds . Fibrin . -AJbnmin Extractives. Potassic chloride Sodic chloride Potassic sulphate Sodic phosphate . Earthy phosphates SEROSITIES AND TRANSUDATIONS. 283 . ConipaieJ with the blood serum it will be seen that the fluids of these transudations are richer in water, poorer in albumin, still poorer in fibrin generators, bat relatively richer in ci7stalline constituents. The pleural transudation is richest in all)umin and solids; then follow the peritoneal, cercbro-spinal, and subcutaneous cedematous eflusions. CHAPTER XIII. PUS AND MUCUS. I. PUS is a creamy, opaque, yellowish white or greenish grey fluid, produced as one of the consequences of inflammation. It is made up of corpuscles floating in a serous fluid. The corpuscles resemble, if they are not identical with, the pale corpuscles of the blood ; they appear to be derived chiefly from the blood by a morbid migration of its pale corpuscles, although it is also very probable that some of them are derived from a later proliferation of the connective tissue or other corpuscles in the inflamed tissue. PYequently also we find granulation corpuscles, free molecules, molecular debris, , _ . , -r . a, in a neutral liquid; 6, after the action and tatty particles, its reaction of ciiiut^ acetic acid; c, mucus from is neutral or very slightly alka- line, this depending on the presence of alkaline carbonates and basic phosphates ; and it has a mean density of 1032. The serum closely resembles that of blood, and, like it, contains serum albumin, fibrinoplastic material, a casein-like body, and another body like myosin; lecithin, cholesterin, fatty acids, and probably also xantliin and leucin are likewise present, particu- larly in altered pus, together with about eight per cent, loosely combined carbonic anhydride and a little hydrogen and nitrogen. In septicaemia the carbonic anhydride and hydrogen increase considerably, serous pus being especially rich in these gases. The proportion of corpuscles and serum is variable : fi'esh jjus of most large abscesses contains 1 7 to 29 per cent, of corpuscles ; the pus of some inflannnations (meningitis, iritis, itc.) may be made up 284 TISSUHS, ORGANS, AND REMAINING SECRETIONS. almost entirely of corpuscles ; while, on the other hand, the pus coming from inflamed bones may only contain 2*5 to 3 per cent, of these bodies. To separate the corpuscles, dilute the pus with a solution of sodic sulphate (1 part satui-ated solution to 9 pai'ts of water) or of baric nitrate (1 part pus, 5 water, 5 concentrated solution of baric nitrate). After some hours the corpuscles can be obtained by decantation and then washed with more of the same fluid. The serurn, though containing in gi^eat part the same components, differs very considerably from blood plasma. They may be classified into albuminoids, as serum albvimin, serum casein, nuclein, &c. ; fats, as oleates, palmitates, and oleo-phosphoric acid ; extractives, and a group consisting of protagon, lecithin, and cholesterin ; also inorganic salts, as sodium chloride, calcic phosphate, carbonate and sulphate, and earthy phosphates ; and gases, chiefly carbonic acid. In some kinds of pus chondrin, mucin, glutin, &c., have been met Avith. Pns generally gives a mean dry residue of 12"7 per cent., but this is very variable. I. Annlysu of Pvxfrom Abscess of Cheeli. Per cent. Water 769 Solids 231 Albumin and dried corpuscles .... 18-0 Fat and cholesterin ...... 2*4 Extractives 1*9 Alkaline and earthy salts 0'9 II. Mean of Three Anah/scs of Pits (T. C. Charles). Water 88-27 Solids 11-73 Albumins 8-02 Waterj' extracts 1 -.^9 Alcoholic „ 0-38 Leucin, tyrosin, and certain extractives . . 008 Ciiolesterin 0-34 Lecithin, cerebrin, &c 0-38 Fats 0-OG Inorganic salts 108 Sodic chloride 0-6.5 Pota-ssic phosphate 0-19 Sodic „ 0-09 „ carbonate 006 Calcic phospliate 006 Spdic sulphate 003 PUS AND MUCUS. 285 III. D)-ird Pus Corpuscles (IIOPPE Skvler). Per cent. Albumin 1343 Nuclcin 33-15 Lecitliizi 7-04 Fat.s 7-01 C'erebrin . . . . . . 5'08 Extractives ..... 433 Insoluble bodies .... 20-07 Organic . Sodium chloride . 014 „ phosphate . . 0-61 Potassic „ . . . . 1-20 Earthy and iron phosphates . . 0-42 Inorganic . IV. Ask of Pus C^llESCHKR). Per cent. 8erura contains about . 0-75 Dry corpuscles contain about . 2-8 1)7-63 2-37 Ash of Corjmscles. Potassic phosphate .... Sodic „ .... Phosphoric acid in organic co'nbination Earthy phosphates .... Sodic chloride Per cent. 1-2 0-6 0-.5 0-4 0-1 2¥ The pus will therefore be seen to resemble lymph closely ; where, however, pus has lain long in an abscess we may meet with peptones, leucin, and tyrosin. To analyse ]?us add to it a dilute solution of sodic sulphate, and after some time the corpuscles will settle, when the serum can be decanted. Boil a little of the serum, and a coagulum of serum albumin will be obtained ; filter, dilute the filtrate with much water, and add a little acetic acid : amyosin-like body is precipitated. Filter again, and test for gelatin and chondrin, which are occasionally })resent, adding to one part a strong solution of mercuric chloiide, which precipitates gelatin, and to the other part a strong solution of alum, -which precipitates chondrin. To test for the cholesteiin, lecithin, fatty and albuminous mate- rials contained in the corpuscles, consult the directions given under these different bodies, or follow the table given on p. 290. Hh.Q pus corpvscles are protoplasmic in their nature, and, as their composition is, or at least is supposed to be, identical with 286 TISSUES, OEGAyS, AND REMAINING SECRETIONS. that of the pale corpuscles, the opportunity may here be taken of studying their protoplasm, which may be regarded as a type of animal protoplasm in general. Protoplasm of Pus Corpuscles, (a) Organic Constituents. 1. Albumins. — There are at least five forms, of which three are soluble in water — an alkali albuminate, an albumin spon- taneously coagulable at 48° or 49°, and a body like serum albumin, coagulating at 70° — and two insoluble in water, of which one is an albumin insoluble in sodic chloride solution, and dissolved with difficulty by dilute hydrochloric acid of j\ per cent., and the other a hyalin substance (Rovida) of the nature of fibrin and allied to globulin, which is soluble in hydro- chloric acid j\ per cent, and in 1 per cent, soda solution (this forms the chief mass of the protoplasm of the pus corpuscle). 2. In addition to these albumins there are also lecithin, cerebrin, cholesterin, fatty soaps, and certain badly known ex- tractives ; in the living and yet amoeboid cell glycogen is found. Gelatin, chondrin, and paraglobulin are not j)resent ; nor in the fresh pus do we find free fatty acids, leucin, or tyrosin. (6) Inorganic Constituents.— i^edts of potassium, sodium, calcium, magnesium, and iron ; part of the sodium is in the form of chloride, and the rest of the sodium, together with the remaining bases, are probably present as phosphates. The nuclei of the pus corpuscles contain, besides lecithin and traces of ash, a body called nuclein, that forms their chief component. A soluble and an insoluble modification of this body are described. This body has also been described as present in spermatozoa, hepatic cells, and nuclei of blood corpuscles. Nuclein, C^o^ 40^0^3^22- Preparation. — Treat pus corpuscles several times with warm alcohol to separate the fats and lecithin ; then digest the residue with artificial gastric juice at 37 to 40°. After 24 hours collect the separated nuclei, which will be found in the bottom of the vessel, in a small loose filter, and wash them there with ether and then with cold water until the washings give no albumin reaction with tannic acid. Now extract the washed nuclei two or three times with warm alcohol. The purified mass is lastly extracted with very dilute caustic soda, the solution filtered and pre- cipitated with hydrochloric acid, and the solution and precipitation again repeated. The precipitate, when well wasluid with Ix tiling alcohol, is soluhk nuclein, having the composition — rUS AND MUCUS. 287 Tcr cent c . 4'J-6 H . 70 N . . HO Per cent. P . 2-5 S . 1-8 . . 25-1 The residue, insoluble in the dilute caustic soda, and which forms the greater part of the nucleus, is the insoluble modijication of nuclein. It is soluble, however, iu moderately strong solutions of the caustic alkalies and in strong hydi'ochloric acid ; treatment with the latter, indeed, changes it into the soluble form. Nuclein is colourless and amorphous, slightly soluble in water, but readily soluble in the alkalies and alkaline carbo- nates. Chloride of zinc, sulphate of copper, and nitrate of silver precipitate its solutions. Some chemists, it should be said, consider this body to be a mixture of one or more organic phosphorus-holding combina- tions with albumin. Abnormal Constituents. — The body named pi/in is really a mix- ture of albumins and not a chemical individual. It can be obtained by digesting recent pus with sodic chloride solution (10 per cent.) and filtering after 24 hours. The insoluble residue is treated with dilute hydrochloric acid and then filtered, the filtrate next treated with soda, and the precipitate collected and dried. The so-called jyyocyanin (Fordos) is no normal constituent of pus, but is due to the presence of special blue-coloured vibriones. A blue colour is occasionally seen upon the bandages of suppurating wounds; it can be extracted ftom these by macerating the coloured pieces in weak alcohol, then evaporating the alcohol, filtering hot, and shaking up the filti^ate with a little chloroform ; the chloroform is next de- canted and treated with dilute sulphuric acid, when a red pigment passes into solution in the acid, while a yellow pigment (pyoxanthose) remains in the chloroform. The acid extract is saturated with baric hydrate, and the filtrate again shaken up with chloroform. On allowing a drop of the latter to evajiorate on a slide fine blue needles will be seen under the microscoj^e. In jaundice the pus may contain bile pigments, and in diabetes sugar. Formic, butyric, and valerianic acids have likewise been met with. II. MUCUS is the term given to the secretion of certain mucous membranes, which are generally provided with the so- called mucous glands, but which in certain cases, as in the ■2SS TISSUES, ORGANS, AND REMAINING SECRETIONS. frontal and maxillary sinuses, the tympanic cavities, &c., are devoid of them. The mucus corpuscle seems to be formed by a sort of budding of the epithelial cell, part of the contents being expelled or transuded outwards, an open cell being left behind. This mucus is found in the mouth, in the stomach and intestine, in the bile, urine, and synovia, in nasal and bronchial secretion, and in certain tumours (myxomata). Properties. — Mucus is very variable in its characters and re- actions, but always gives somewhat of a ropy consistency to the fluids containing it. Mucus is generally bright and trans- lucent, but sometimes more or less opaque : it may be colour- less, white, yellow, or greenish. The stringy character possessed by mucus depends on the presence of mucin, of which less than 1 per cent, is capable of imparting this property to the fluid in which it is present. Although the mucus obtained from diiferent parts varies, yet this mucin, its imporant constituent, is always the same. Mucus serves to protect and cover surfaces, and in the case of buccal mucus it possibly aids the saliva in its action upon sugar ; it serves also as a means for removing from the body certain organic and inorganic excrementitious materials. Buccal mucus is a transparent, viscid, and alkaline liquid, holding epithelial cells and mucus corpuscles in suspension ; stomachal mucus is thready, greyish, and alkaline ; intestinal inucus is greyish, viscid, finely striated, alkaline, and rich in fatty particles and mucus corpuscles ; vesical mucus gives a cloudy appearance to urine (p. 536) ; vaginal mucus is slightly viscid and always acid ; that of the neck of the uterns is slightly viscid or gelatinous, greyish, transparent, and alkaliii'.'. In the normal state very little mucus is formed, but in mucous catarrh it is produced in large amount. It is then clearer and more alkaline than normal, but at a later stage it becomes thicker, and in addition to abundance of epithelial cells we find mucus corpuscles in great numbers, as well as large gi'anular exudation corpuscles, leucocytes, and fatty and proteid granulations. There appears to be an aluindant secretion of mucus during digestion. Composition. — It generally conlains mucus cor})Uscles similar PUS AND MUCUS. 280 to, if not identical with, the palo corpuscles of the blood, fine fatty granules, and sometimes crystals of cholesterin, and consists mainly of water holding in solution 4 to 5 per cent, of solids made up of mucin, traces of albuminoids, extractives, fats, and mineral salts. Analysis of Mucks. Tracheal Nasal (Wright) (Beuzeuus) (Nasse) Water 95-6 1)3-37 95-56 Solids 4-4 6-63 4-44 Mucin 3-2 5-33 2-37 Extractives 04 1-04 0-98 Fats — — 0-28 Inorganic salts .... 0-5 0-56 0-81 Chlorides, carbonates, sul- pliates, and phosphates of soda and ijotash The pyin of pus differs from the mucin of mucus in being pre- cipitated by mercuric chloride and neutral acetate of lead, and its jirecipitate with acetic acid is insoluble in excess. From chondrin it is distinguished by its precipitate with alum being insoluble in excess. Small mucus calculi are sometimes met with, consisting of mucin, fat, and phosphate and carbonate of lime and magnesia. CHAPTER XIV. METHODS FOR THE EXAMINATION OF SEROUS FLUIDS. Two methods are given. By means of the first the albu- minoid constituent may be readily determined, and by the second the examination may be made with more completeness not only for albuminoids, but also for numerous other organic and crystalline constituents. I. Qualitative Analysis for some of the Constituents of a Serous Liquid {after HorrE Seyler). 1. Mix part of the liquid with 10 to 20 times its volume of water, add a few drops very dilute acetic acid, and then pass a continuous current of carbonic acid gas through the mixtnre and let it stand ; if a flocculent precipitate forms, then a globulin or alkali albumin is present. U 2-)0 TISSUJES, ORGANS, AND REMAINING SECRETIONS. 2. The above flocculent precipitate is divided into two parts. {a) Add to one of these a little strong sodic chloride solution; if the precipitate dissolves the liquid contains myosin or an analogous body. {h) To the rest of the precipitate add hydrochloric acid ^-^ per cent. ; if a solution occurs the precipitate may be myosin, fibrinogen, or casein. 3. Boil the liquid decanted from the precipitate obtained in 1 : a coagulum indicates serum albumin. 4. Add to some of the serum a few drops of defibrinated blood (obtained by squeezing a blood clot), stir well, and lay aside in a moderately warm place for 24 houi-s : a coagulum in^ic&tea fibrinogen. 5. To a portion of the original liquid add a little pericardial serum (ox), and if a coagulum appears it is due to the presence of fibrinoplastin. 6. To a little of the liquid add acetic acid : (j) if a stiingy precipi- tate insoluble in excess of acetic acid or sodium chloride is formed, mucin is present; (ij) if the precipitate formed by the first drop or two of acetic acid dissolves in the least excess, then the precipitate is probaVjly jxtr albumin. To confirm, j)recipitate a little of the original liquid with three times its volume of alcohol, filter, dissolve the precipitate in water, and let the solution stand aside ; if paralbumin is present the solution gi^adually becomes more or less viscid. II. Examination of a Serous Liquid {after Gorup Besanlz). A. Boil a portion in a test tube, acetic acid having been added. 1. A coagulum is prodicced. Divide it into two portions. (a) Add a few drops of hydrochloric acid; if the precipitate disappears albumin is not px-esent, but probably earthy phosphates. (h) If the precipitate does not disappear on the addition of the hydrochloric acid, add more of the same acid and boil, when the l)recipitate will gi\adually dissolve with the formation of a red solu- tion — a lhum,in. (c) If the first coagulum obt lined on boiling is I'eddish, then hsematin and globulin are probably present ; digest with alcohol con- taining sulphuric acid, and test for these bodies (see under Blood). 2. If no coagulum is produced, proceed as follows; or if this has occurred, then use the filtrate. (a) Boil, and if only a turbidity is produced, add a;!etic acid : a flocculent deposit indicates paralbumin. Confirm by testing with potassic ferrocyanide and nitric acid. {J)) Test also for luelalhuiain by adding alcohol ; if a precipitate is obtained soluble in a large excess of water, then this body is present, and no precipit4ite will be given with potassic ferrocyanide. EXAMINATION OF SEROUS FLUIDS. 201 ((•) Tf the fluid remains perfactly char on hoilinij, then mix a portion with potassic feirocyanide solution : casnu or globv.Un is thrown down. (j) Uoil witli a solution of calcic chloride and test with rennet : a precipitate points to c tsein. (ij) Neutralise the solution after it has been made acid or alkaline : a precipitate points to globulin. B. To some of the liquid add aatic acid : p>/in, mucin, and chondrin are precipitated. (rt) Test the liquid with mei'curic chloride : j^yi^^ is precipitated. Confirm with tincture of galls and neutral acetate of lead. The precipitate with acetic acid as well as with alum is insoluble in excess. (6) A turbidity may be due to chondrin. Concentrate some of the liquid, and if chondrin is present a jelly will form on cooling. Confirm with alum and metallic salts. (c) The precipitated mucin gives a rosy red coloration with Millon's reagent, and a yellow coloration with nitric acid. The precipitate with acetic acid is soluble in excess. C. Concentrate a little to a small bulk and leave it to cool : if gelatin is present a jelly is formed. Confirm with mercuric chloride. D. The original liquid, from which albumin, if present, must first be separated by boiling, is evaporated at a gentle heat to one-third its volume, then l)oiled, and left to cool. A jrrecipitate indicates urates. Add acetic acid and examine under the microscope, when rhombic crystals of uric acid will be seen. Confirm by the murexid test. If the precipitate is not altered by the acetic acid it may be due to calcic sulphate, magnesic phosphate, or to allantoin, tyrosin, calcic hippurate, or benzoic acid. For special methods of detection see under each of these bodies in the general text. E. Tlie concentrated liquid gives no precipitate when cooiod. Evaporate to a syrup and leave aside for several hours; if crystals form, let the liquid stand some time longer : kreatin, kreatinin, ghjcocin, leucin, allantoin, taurin, sarkosin, inosit, sodic cJdoride, &c., may be present. First determine if the crystals are organic or inorganic by heating a portion on platinum foil, noting if any charring occurs or if a fixed residue remains ; then examine the crystals under the microscope. (For identifying tests consult the text.) F. The syrupy residue, or the mother liquor from which the crystals have been sepaiated, is next evapoiated nearly to dryness, and the residue exhausted with absolute alcohol. r.i 202 TISSUES, ORGANS, AND REMAINING SECRETIONS. (a) Concentrate a little of the alcoholic solution, then dilute with water, and test for bile jngment with yellow nitric acid (p. 203). {h) Treat a second portion in the same way, but apply the test for the hiUarjj acids (p. 202). (c) Evaporate a little to dryness, dissolve the residue in water, and test for sugar with Fehling's solution, {d) Evaporate a considerable portion to a small bulk, add pure nitric acid to the residue when cooled, and immerse the vessel in ice- cold water : laminated crystalline precipitate indicates rirea. Confirm with the ordinary tests and note if any hippuric acid is present. (e) To some of the concentrated alcoholic extract add a little syrupy solution of chloride of zinc : a crystalline precipitate may be due to kreatin or kreatinin. {/) Heat a portion of the concentrated alcoholic extract with oxide of zinc, filter hot, and evaporate a drop of the filtrate on a glass slide ; examine the deposit : if club- or tun-shaped crystals are to be seen, then lactic acid is present. G. The residue insoluble in the alcohol must be extracted with water, which takes up casein, pyin, extractives, and soluble salts ; then with dilute caustic potash, which dissolves uric acid, hypoxan- thin, and guanin ; and lastly with dihite hijdrochloric acid. The residue may contain insoluble albuminates, mucin, and pro- bably silica. H. Part of the original liquid is evaporated to dryness and the powdered residue exhausted with ether. The ether extract is then to be evaporated and fats looked for. » CHAPTER XV. EPITHELIAL STRUCTURES. I. Epitheliums. — These are cellular tissues that invest Ruch free surfaces as the skin and alimentary canal, or such closed cavities as the vascular and lynii)hatic systems. The cf;lls are united together by a sort of intercellular cement, which by its reducing action on salts of silver can easily be brought into view. Except in tlic scales on llic suiface uf the skin these EPITHELIAL STRUCTURES. 2!i3 epithelial cells are provided with nuclei as well as with a certain amount of cell contents of a protoplasmic nature, varying much, however, with the age of the cell, but generally formed of a proteid body containing granules of different kinds in its substance, such as fat, pigment, salts, &c. If glandular epithelium is also included here we find the cellular protoplasm charged in addition with the secretion and excretion elements. Under the epithelial tissues are ej^idermis, epithelium, hairs, and nails, &c., and among them we may also include the crystalline lens. Keratin. — When one of these epithelial structures, such as horn, is finely divided and digested successively with boiling water, alcohol, ether, and dilute acids, a body remains behind of more or less in- constant composition, to which the name keratin has been applied, and which accorcUngly cannot be regarded as a pure chemical com- pound. This keratin, which seems to be the chief component of epidermic structures, is a body closely related to albumin, yielding, like it, leucin and tyrosiu when decomposed with boiling dilute sulphuric acid. It also contains sulphur, as can be shown by boiling some hair or paruigs of nails with a little caustic potash, and then adding hydrochloric acid, when hydric sulphide will be evolved. Keratin is found in all the tissues developed from the ectoderm or horny layer of the embryo, and is more or less characteristic of this layer, j iist as hannoglobin or globulin is of the mesoderm and mucin of the entoderm. Keratin is an albuminoid, characterised by the large amount of sulphur contained in it, which is in part loosely combined. It is related in some respects to elasticin. Its percentage composition is = 50-51-6, H = 6-4 -7-2, N = 16-3 - 17-9, S = 0-7 - 5-0, = = 20 -22' C ■4. Hairs (Laek) . 50-65 Nails > (MULDEU) 51-00 Epidermis (Mdldeu) 50-28 H . 6-36 G-9i 6-76 N . 17-14 17-51 17-21 . 20-85 21-75 25-01 s . 5-00 2-80 0-71 Keratin is insoluble in alcohol and ether, swells up in boiling water, and is soluble in the caustic alkalies ; it is not liable to de- compose, and melts when heated, burning with a characteristic smell Under pressure and at a temperature of 150° keratin dissolves pai'tially, sulphuretted hydrogen being evolved ; and the solution is 294 TISSU£:S, ORGANS, AND REMAINING SECRETIONS. precipitated by acetic acid and potassic ferrocyanidc. When boiled with dUute sulphuric acid or the caustic alkalies, keratin furnishes aspartic acid and the volatile fatty acids like acetic, butyric, and propionic, as well as ammonia, leuciu (10 per cent.), and tyrosin. (4 per cent.) II. Hairs are soluble in water under a high pressure, and the solution is precij)itated by chlorine, acetate of lead, tannic acid, and the mineral acids. They are soluble also in great part in the stronger acids. Human hair contains 4 to 5 per cent, sulphur. Silica has also been found in hair to the extent of O'll to 0*22 per cent. A granular brown pigment is present in the medulla of most dark hairs, but it is wanting in white and even in brown hairs. Of inorganic constituents the amount is variable. Nails are rich in potassic phosphate, feathers in silica, and hairs con- tain 0*5 to 0*7 per cent, of ash. Of luater the hair of the head contains 13*14 per cent.; that of the beard, 12'83 per cent.; and the nails, 13*74 per cent. But in summer the proportion of water may rise to 30 per cent. Ash of hair may be stated to consist on the average of alkaline sulphates 23 per cent., calcic sulphate 14 per cent., oxide of iron and manganese 10 per cent., and silica 40 per cent. Ash of IJuman I/air— in tlie 100 Parts (Baudrimont). White Red Browu Black Sodic sulphate . 22-08 18-43 Calcic phosphate 2053 10-29 10-13 1504 „ carbonate 1618 4-03 5-60 4-62 „ sulphate . ] 3-.57 Silicates , 12-30 42-46 30-66 6-61 Oxides of iron . 8-38 9-66 10-86 8 09 Magnesic carbonate 5-01 6-19 4-26 2-89 Sodium chloiide trace 0-94 2-45 3-30 III. The Horny Structures are insoluble in water, alcohol, and ether ; soluble, with the exception of nails, in acetic acid after long boiling ; they swell up also and dis.solve in hot sul- ])huric acid. Dilute sulphuric acid acts upon these bodies as upon albumin, causing them to yield leucin, much tyrosin, ammonia, EriTIIELIAL STltUCTURES. 295 and fjitty acids. A blue or violet solution is obtained by heat- ing them with concentrated hydrochloric acid. Nitric acid dissolves them at a gentle heat, colouring them yellow, and yielding oxalic acid as a terminal product. The younger epithelial structures are readily soluble in caustic potash, but the older ones are insoluble or nearly so. Strong boiling alka- line solutions, however, decompose them, with the formation, as with albumin, of leucin, tyrosin, ammonia, hydrogen, and volatile fatty acids. IV. The Crystalline Lens. — This body differs somewhat from every other tissue in the body. It consists of a parenchyma invested by an elastic capsule. The latter is quite structure- less and very elastic and brittle. The imrencliyma pi-esents a layer of granular and nucleated six- sided epithelial cells that lie behind the anterior layer of the capsule and connect it closely to the chief mass of the lens, which consists of flattened hexagonal bands or fibres, about ^Truu^^ of an inch wide, which lie in layers and run from the anterior to the posterior round the margin of the lens. Each fibre, in fact, may be regarded as a greatly elongated epithelial cell (Babuchin), and this accounts for the close connection between the fibres and the layer of cells behind the anterior thick fold of the capsule. Every fibre, except those of the centre, is provided with an elliptical nucleus that is situated mostly towards the margin of the lejis, so that the nuclei form a curved zone constituting a prolongation of a regularly arranged series of epithelial nuclei (Meyer). All these fibres are flattened in the plane of the lamina in which they lie, and are six-sided on cross section : by some authorities they are regarded as tubes with hyaUne walls and a fluid interior. The density of the lens varies, increasing towards the centre, the peripheral layers being 1'076 and the central 1*194; the index of refraction of the central layers is also greater than that of the peripheral. Its reaction is alkaline, and water forms two-thirds of its substance, the solids having the following composition: — LcHS of Ox (Laptschixsky). Albumins . . 34-93 Fats . . 0-29 Lecithin . 0-23 Soluble salts 0-53 Cholestcrin . 0-22 Insoluble saUs . . 0-23 296 TIS;SUi:S, ORGANS, AND REMAINING SECRETIONS. Albumins . IV VJ «• ^C/IO ■t:\lt'. . 85-37 Alcoholic extract 1-45 Cholesterin ioo Watery „ . 2-76 Lecithin . 0-8 Sr>luble salts 2il Fat . . 1-19 Insoluble salts . 1-45 The salts are made up of chlorides, sulphates, and phosphates of the alkalies, with calcic phosphate in small amount. According to Cahn only one albumin is present — a globulin sub- stance like vitellin. The lens, however, according to Laptschinsky, contains at least two albuminous bodies, one soluble and the other with difficulty soluble in water, but readily soluble in sodic chloride solution. According to Berzelius, again, if the lens is rubbed up with washed sand and then digested with water, a solution is obtained containing cnjstallin or pa7-aglobtilin, which separates when a current of carbonic acid gas is passed through the liquid ; and is also precipi- tated by dilute acetic acid, and when precipitated is insoluble in water containing no air dissolved in it, but if a little oxygen is passed through the water in which it is suspended an opalescent solution is formed, which gives a coagulum when heated to 93°. In addition to this paraglobulin there is present in small amount a body resembling casein, and precipitated by the addition of very dilute acetic acid to the clear filtrate from the first precipitate ; and also a third albuminoid body in the filtrate that is coagulated by heat when the two preceding bodies have been removed. The capnde is of an elastic nature, but it probably contaiuo a keratin- like body. After death and during life a coagulation of the albumins may occur, leading to opacity ; an opacity may also be produced by a separation of cholesterin crystals, of earthy phosphates, or of carbonate of lime ; fatty degeneration may likewise occur, and entozoa may show themselves. Another epithelial structure, enamd, should be taken up here, but for convenience sake its constitution will be given under Teeth (p. 312). 2o; CHAPTEK XVI. COJSiNECTIVE TISSUES. The term connective tissue has been variously applied, some liistologists including under it only white and yellow fibrous tissue, while others regard cartilage, bone, and dentine as being of the same nature as white fibrous tissue, and accordingly group them under the same head. As the name implies they all con- nect or support parts ; they have also more or less of a common origin, being derived from similar embryonic cells, that develop around them a matrix or intercellular substance in which the chief developmental changes subsequently occur ; and they often in parts run imperceptibly one into the other in such a way as to indicate the closest relationship. The connective tissue is very generally spread throughout the body, supporting, binding, and investing parts and organs, and also taking an important share in general nutrition, as the whole connective tissue may be regarded as constituting a con- tinuous system of channels, passages, interstices, and reservoirs which are in direct relationship with the lymphatic system. In areolar tissue the spaces are large and freely communicate, but in membranes similar spaces exist, though they are much smaller, constituting delicate channels. Wherever, in short, the tissue is found it presents spaces or interstices that com- municate freely and form a system of lymphatic spaces. And, as this tissue penetrates into all the organs and tissues, it will be seen that the arrangement results in the tissues everywhere being placed as it were in a great lymphatic sac, just as the intestines are suspended in the peritoneal cavity (Ranvier). As its structural elements connective tissue presents cells, fibres, aiul a cement substance binding the fibres together. I. Cells. — -These are either fixed or amaihoid. The amcehoid are of the nature of pale corpuscles, and may either be wandering leucocytes or buds from these or from some of the fixed cells. "While some are of the size of pale corpuscles, others are much larger, and 298 TISSUES, OltGANS, AXD liEMAIXING SECEETIONS. are chiefly uf a rounded form, although some are oval or even spindle- shaped (as occasionally found in the perivascular cellular tissue). The fixed cells vaiy in shape, but they are generally moi'e or less flattened. They are devoid of a cell wall, although fat cells, that are derived from them, develop cell walls at the expense of the peripheral portion of the protoplasm. The gi-eatest number of these corpuscles consist of a granular pi'otoplasm with a granular nucleus, and are pi'ovided with branched processes; others are moi-e or less quadrilateral in shape, with well- marked nuclei, but devoid of processes ; others again present a fusiform appearance, though many thus described are really delicate flattened bodies seen sideways or after having shrunk. Waldeyer has also described certain other cells under the heading of connective- tissue corpuscles, as, for example, the parenchymatous cells of the suprarenal capsule, and special subendothelial groups of cells met with in the testicles. Peculiar cells, called 'plas'nia corpuscles on account of their peculiar richness in granular protoplasm, are likewise to be seen. They are larger than the wandering cells, and are round, oval, or spindle-shaped, and are to be found especially in the peri- vascular tissue and in the connective tissue of glands. In adi'pose tisstie, which consists of a series of rounded or polygonal cells (3 J-y to 3-g-o of an inch in diameter) filled with fat, the cells may be regarded as direct derivatives of the connective-tissue corpuscles, the particles of fat gradually invading the substance of the cell, swelling it up, and compressing the nucleus and the remains of the protoplasm towards the exterior, where a membranous wall has already been developed at the expense of the protoplasm. II. Fibres. — These are of two kinds — the Wtiie, which are very fine iTnbranched fibres, with indistinct outlines, lying generally in wavy, tough, and flexible, glistening bundles ; the ydlovi, which in mass have a faintly yellow tint, and jiresent well-marked outlines, owing to their refracting the light strongly, also branching and anastomosing freely. The yellow are much more brittle than the white, and imdcr manipulation they readily break, the ends curling up and showing transverse lines of fracture. The white average ~^i^}fQ-sj to ^^j-otfit ^^ an inch in diameter, though they are frequently met with as fine as iTTrUu; and the yellow are about ^-^^^^ to Ti-,ro.r Acetic acid swells up the white fibres, removing all appearance of fibrillation, while it has no such action on the yellovv or elastic fibres. Both sets of fibres are generally associated together, but one or other greatly predominates, so that while in tendons and ligaments, CONNECTIVE TISSUES. 299 for example, the white fibres are the chief constituent elements, in the ligamentum nuchse and the true vocal cords the elastic fibres greatly preponderate. The white fibrils form bundles varying in thickness, and these bundles lie parallel in tendons and ligaments, and more or less parallel, with some interlacement nearly in the same plane, in fasciae and membranes, while in areolar tissue the bundles lie loosely interlaced in different planes, and in the cutis and in mucous and serous membranes the interlacement is much closer and more complicated. The elastic fibres and the connective-tissue corpuscles lie between and around the white bundles. The elastic tissue may also present itself in the form of close net- woi'ks and transparent homogeneous membranes. The retiform tissue may be regarded as consisting of a solid plexus of fine fibrils, upon the nodes of which little connective- tissue corpuscles are usually fixed. III. Cement. — The fibres are held together in bundles by a trans- pai'ent substance, which is soluble in lime or baryta w^ater, and precipitable therefrom by acetic acid, this precipitate being mucin. Reference has alreiidy been made to the afiinity of this cement sub- stance for silver salts. Classificat.on. — Four varieties may be distinguished : — 1. Fibrillar Connective Tissue. — [a) White fibrous, fasciculated, as in ligaments and tendons; or membranous, as in fasciae, aponeuroses, etc. {b) Elastic, also in fasciculated and membranous forms, as the ligamenta subflava, true vocal cords, and capsules of lens and lungo. 2. Homogeneous Connective Tissue occurs chiefly in the form of membranes, as the hyaloid membrane of the eye, the capsules of Graafian follicles, &c. 3. Mucous or Jelly-like Connective Tissue exists chiefly in the embryonic condition, and is made up of a soft, transparent funda- mental substance, in which lie connective-tissue corpuscles. Examples are found in Wharton's jelly of the umbilical cord of the young embryo and the vitreous humour of the eye. 4. Reticular or Retiform Connective Ti^siie consists of a close network of fine branched fibrils, upon the nodes of which little con- nective-tissue corpuscles are flattened out. It used to be described as a network formed by the branched processes of connective-tissue corpuscles. Examj^les are met with in the framework of lymphoid tissues and the neuroglia of the central nervous system. Chemical Composition. — The white fibrous tissue is made up of collagen^ a body that furnishes glulin or gelatin when boiled in water ; and the elastic tissue yields elastin. These bodies 300 TISSUES, OliGAXS, AXB ItEMAINING SECRETIONS. have already been described (see pp. 128-135). In their de- veloping foetal condition the white fibres yield mucin (p. 132) instead of gelatin, in which respect they resemble the mucous and retiform tissues. CHAPTER XVII. CARTILAGE. Cartilage consists of cells and intercellular substance, by the latter of which it is essentially characterised. The cells possess no distinctive appearance, their only specific property being the possession of rings of intercellular substance ; in their early or active condition they contain glycogen, while in their inactive period particles of fat present themselves. In the adult state each cell is provided with a capsule, which is of the same nature as the matrix, but it is devoid of this covering in its young condition. .All cartilages, with the exception of the articular, are covered on their free surface by a fibrous membrane, the perichondrium, between which and the intercellular substance a very close union exists. Classification. — In addition to foetal cartilage there is cellular cartilage, in wliich little or no intercellular substance exists ; hyaline cartilage, in which the intercellular matrix is more or less clear and free from filjres ; and fibro-cartilages, in which the matrix is pervaded by fibres. 1. Cellular Cartilaye. II. Hyaline Cartilage. 1. Tem'porary. — The cells are small and angular, and exhibit no definite arrangement unless when the car- tilage is about to undergo ossification, when tbey increase in size, multiply by endogenous division, and arrange themselves in rows perpendicular to the line of ossific deposit. 2. Arliciclar. — Free suifaco devoid of perichondrium, surface cells flattened in the direction of the surface, and lenticular in shape, dee^) cells columnar and perpendicular to the surface, and the intermediate cells more or less rounded. 3. Costal Type. — Free surface coveied with perichondrium ; surface cells small and flattened in the direction of the peri[)hcry, and forming a thick layer ; the deeper cells larger and more rounded, and CARTILAOB. 801 the deepest cells larger still, and more or less elongated, but exhibiting only a slight tendency to be arranged with their long axes perpen- dicular to the surface. ((f) Costal cartilages. (b) Ensiform Ciirtilage. (c) Cartilages of lai-ynx, trachea, and bronchi. (d) ^aaal cartilages. III. Fihro-Cartilagcs. 1. WJdle Fihro-Cartilages. — The matrix is composed of connective -tissue fibres. Interarticiilar fibro-cartilages, cartilage deepening joints (as the glenoid and cotyloid), intervertebral discs, &c. 2. Elastic Cartilages. — The matrix contains networks of fine elastic fibres. Ear, epiglottis. Eustachian tube, and the small car- tilages of the larynx. Chemical Characters. — When the permanent cartikges are boiled we obtain chondrin as the product (see p. 130), thia being derived from the intercelluLar substance and the capsules, but not from the cells. A somewhat similar body is obtained by boiling the cornea. The cartilage cells themselves are not made up of ossein or chondrin, but contain a coagulable globulin albumin, which gives a pur[)le-red colour when treated with sulphuric acid and sugar, and a mahogany brown to a bluish violet with iodine (particularly the young cells). Fatty granules are often present, especially in the old cells. The intercellular or ground substance of hyaline cartilage consists of cliondrogen and yields chondrin on boiling ; the matrix of the connective tissue or fibro-cartilages consists of collagen, and yields gelatin on boiling ; while by boiling the elastic cartilages only a part of the intercellular substance is dissolved, furnishing gelatin, the rest remaining insoluble and long unaltered by caustic potash, acetic or sulphuric acid. Cumj)ositio/i (HorPE Seyler). Costal cartilage Articular cartilage Water .... 67-67 73-59 Organic matter . . 30-13 24-87 Mineral constituents . 2-20 1-54 Costal Caiiilage—'Ma.ri, a;t. 20 (Fkommhertz and GUGEET), Water 62-00 Chondrin ..... 33-26 Fat 1-33 20-J riSSUJSS, ORGANS, AND REMAINING SECRETIONS. Salts B-40 Sodic carboDale 1-19 „ sulphate . 82 Calcic carbonate 002 Sodic chloride . 028 Maonesic phosphate 0-23 Calcic ,, OU Sodic ,, 0-03 Pota=s'c sulphate 0-0-i Oxide of iron . . 0'03 Ash of CaTtila(ic—Y axidiiion with Age (Bibra). In a child \ year old . . . 2'24 per cent. „ „ 3 years „ . 3-00 „ girl net. 16 years . 7-29 „ woman a;t. 25 years . . 3-92 „ man „ 40 „ . . 6-10 Asli of Costal Cartilages (Bibra). Child, ret. 3 years Man, ffit. 22 Man, ret. 40 Potassic sulphate . . 48 68 26-66 79-03 Sodic „ . . 10-93 44-81 1-22 „ chloride . . 7-18 6-11 1-95 „ phosphate . . 3-00 8-42 0-93 Calcic „ . . 21-33 7-88 13-09 Magnesic „ . . 8-88 4-o3 3-78 Althoiigli chondrin lias already been referred to, the opportunity may here be taken to compare its percentage composition with that of several allied bodies : — c N H s Albumin . 52-7 to 54-5 15-4 to 16-5 6-9 to 7-3 20-9 to 23-5 0-8 to 2-0 Collagen 5002 18-06 6-75 24-59 0-58 Chondrin . 50-0 14-4 6-6 28-4 0-6 Mucin 49-5 9-6 6-7 34-2 Elasticin . 55-5 16-7 7'4 20'4 Keratin . 50 to 51-6 16-2 to 17-9 6-4 to 7-2 20 to 22-4 0-7 to 50 Through the action of sul[)huric acid albiunin, keratin, and mucin furni.sh Icucin and tyrosin, but chondrin and ela.sticin only yield leucin. 303 CHAPTER XVIir. ]iOXE. BoxE is one of the indifferent or mechanical tissues of the body. It differs somewhat in appearance, as well as in chemical composition, in different parts of the body. General Constitution of Bone considered Histologically. — Bone consists of a sizrics of layers called lamella', which are arranged round spaces of different kinds. These spaces are the Haversian canals, the cancelli, and the medullary canal. The Haversian canals form a comparatively close network of short curved tubes throughout the substance of the compact bone, and thus establish a free communica- tion between the exterior of the bono and the large central or medullary cavity. Towards the ends of the same bones some of the Haversian canals open up into the cancellated spaces, which may be regarded merely as dilated Haversian canals, while others form dilated loopings and curved arches beneath the articular cartilage. Con- tained in these canals are the blood vessels, and in the largest of the canals and in the other spaces we have in addition red and yellow mari-ow. The blood ves-els communicate freely with those of the membrane covering the exterior of the bone, ihe periosteum, and with those of the endosteum in the interior of the bone. The lamellae form concentric layers round all these spaces, and where the latter are small and regular, as with the Haversian canals, the lamellffi are numerous, and constitute the so-called Haversian systems; but where the spaces are large and uregular, like the cancelli, there is not the same uniformity in the arrangement of the laraellifi, nor the same number of them present. In bone, after it has arrived at matui'ity, we have, further, concentric lamellse more or less parallel with the periphery, lying round the exterior, and also more internally among the Haversian systems, although the latter are found at a much earlier period, having been formed under the periosteum, but in process of development coming to lie more inter- nally among the subsequently- formed systems. Between the lamellae are a series of small oval spaces, the lacunee, which contain the bone corpuscles, and from them radiate a set of very fine branching canals, the canaliculi, for the more complete irrigation cf the bone tissue. 304 TISSUES, OliGAXS, AND REMAINING SECRETIONS. In living l)one a certain amount of absorption of old bone, and a corresponding growth of new bone, is always going on, the former showing itself in the Haversian spaces, in which new bone is laid down in the form of concentric lamellee. Chemical Composition. — Although bone takes the place of temporary cartilage in the organism, it is derived from it neither chemically nor anatomically, the cartilage merely acting as a temporary substitute for it. Bone consists of an organic substance, ossein, a modification of collagen, intimately combined with a mineral substance, the so-called hone earth, in the proportion of about thirty of the ossein to seventy of the bone earth. This bone earth is itself a mixture of several salts, the chief of -which is tribasic phos- phate of lime, Ca32P04 [or, according to Hoppe Seylek, 3(Ca32P04)CaC03] ; there is besides about 9 per cent, of calcic carbonate, 3 per cent, of calcic fluoride, and 1-7 per cent, of magnesic phosphate. Rone also contains water and fat. The general composition of normal undried bone without any separa- tion of fat, marrow, or blood lymph, may be given as — Water . 50-00 per cent. Fat . . 15-75 0?sein . 11-40 „ r.one earth . 21-85 „ (HopPE Seylek'i 11 to 14 per cent, of the water is combined witli the ossein, apparently after the nature of water of crystallisation in crystals. The composition is thus given by Heintz and Zalesky : — Heini'z Zalesky Orf^anic substances Inorganic „ 30-47 to 31-12 (;!)-53 „ 68-88 84-56 65-44 Ash in 100 parts- Calcium .... rhosplioric acid Carbf)nic „ Chlorine .... Fluorine .... Magnesium 38-5t) to 38-56 53-75 „ 53-87 5-44 „ 5-51 1-75 to 1-58 0-48 40-13 62-16 7-81 0-18 0-23 0-29 BONE. 305 Oi- the ((sh may be thus expressed : — Tribasic phosphate of lime . „ „ magnesia . Carbonate of lime .... Calcic Huoiide (including chloride) . Pfluger obtained 5*84 per cent. CO.j from bone ash by the action of phosphoric acid on the ash in vacuo. 83-89 to 87-7 104 „ 1-7 8!) ,, 13-03 0-70 „ 4<) Human bone Beiizki.ius FllEUICHS Ossein ..... 32- 1 7 Compact 31-5 Spongy 38-2 Phosphate of lime . Fluoride of calcium 51 04 2()() ]■ 58-7 50-2 Carbonate of lime . ]i:;() 10-1 11-7 Soda, with sodic chloride 1-20 Phosphate of magnesia . Vessels i-k; 113 Ttihle shotving Infiveiice of Arje, \c. (BiBRA). Phosphate of lime, with a little calcium fluoride .... Carbonate of lime .... Phosphate of magnesia Soluble salts ..... Ossein Fat CliiW (2 months) Middle-a ged man Tibia Xnna Femur Rib 57-54 56-35 59-63 55-66 G02 6-07 7-33 6-64 103 1-00 1-32 1-07 078 1-G5 0-69 0-62 33-86 34-02 29-70 33-97 0-82 101 1-33 204 The difiierent bones of the ^keleton differ slightly one fioni the other in chemical composition ; and the inorganic constituents are said to increase with age (Bibra) ; but the increase is only very slight ( Fremy), the greater fragility being due to the increased porosity of the bone in old age. Compact bone is about 7 to 8 per cent, richer in inorganic constituents than spongy bone (Frerichs) ; and while the spongy bone is richer in water than the compact, the bones of thin people, as a rule, are richer in water than those of fat people. A prolonged deprivation of earthy salts causes the earthy salts to diminish in the case of pigeons, and these salts, it appears, must be given in the form in which they exist in cereals and in bread (Edwards). The triba.sic phosphate in the food dissolves in licjuids charged with carbonic acid gas with the following decomposition : Ca32P04 + 4CO2 + 4H2O = CaH42P04 (acid phosphate of lime) 4- 2CaH,,(C03)o (bicarbonate of lime). How the tribasic phosphate enters, or in what state it exists in tlic blood, it is difficult to say, X 306 TISSUES, ORGANS, AND liEMAINING SECRETIONS It may be I'endcred soluble l)y tbe action of free carbonic acid, as we have j list seen, or by the alkaline chlorides, or eLe by organic substances. The bone earth appears also to be subject to constant change in the living bones, a portion being redissolved in some of the alkaline salts of the blood and excreted by the intestine (Recklinghausen). The proportion of the organic and inorganic coiistiluents remains very constant, though it differs somewhat in different animals, and even in different .parts of the same animal, of which examples have been given above. While the oi-ganic matter in human bones is about 34"56 per cent., in the ox it averages about 32'02 per cent. Next to enamel bone is the richest in inorganic salts of any tissue in the body. The Marrow differs in different situations. In the shaft of long bones it is yellowish in colour and resembles ordinary adipose tissue, the cells being supported by a sort of retiform tissue, and scattered among them a few true marrow cells may be found. In this yellow marrow there is about 96 per cent, of fat, with some cholesterin, and small quantities of hypoxanthin, albumin, and occasionally lactic acid. The framework sup- porting the softer structures yields mucin. In the cancellated ends of long bones, in the vertebrae, in short bones, and in the flat cranial bones the marrow is reddish in colour and contains few adipose vesicles ; but true marrow cells, resembling pale corpuscles in many points, and like them possessing amoeboid movement, are present in great numbers, as well as cells that are described as transition forms between the narrow cells and the coloured corpuscles of the blood; likewise large clumps of multinucleated protoplasm {myeloplaxes of Robin). The red marrow may have a mucous appearance, as in the case of the cranial bones. In addition to a small proportion of fat, red marrow yields much albumin and salts, and an acid resembling lactic acid. Ked marrow acts probably like the s])k'nic jailp in disin- tegrating coloured coqjuscles of blood, and it appears also to take ]),irf in the generation of new red corpuscles. Pathology. — In b'.rdxnriiiji \\Hi led marrow l)ecomesof a dirty greyish white, and in ) The Ash and Organic Matter. — Calcine in a porcelain crucible the dried bone obtained in (a) at as low a temperature as possible : the lo.ss in weight gives the organic matter, and the residue the ash. It is well, befoie weighing, to saturate the calcined residue Avith amnionic carbonate, and then to heat again to an elevated tempera- ture. (<:) TJia Earth ij PJniupJiales, d-r. — Dissolve with the aid of a gentle lieat tliu ash obtained in (A) in as little moderately dilute hydiocliloric BOXE. ,'J09 acid as possible ; add ammonia in excess to the solution : a precipitate is thrown down chiefly of phosphate of lime, with a little phosphate of magnesia and calcic fluoride. (As a trace of iron is present in old bones, if this is to bo estimated the ammonia precipitate is to be treated with acetic acid, and the insoluble phosphate of iron collected on a filter, washed, dried, calcined, and weighed. With the acetic acid solution we then proceed as in ij.) Filter and wash the pre- cipitate M'itli water containing ammonia. (j) The Lime Present as Carbonate. — To the filtrate add oxalate of ammonia or potash to comj)Iete precipitation, boil, filter, dry the pre- cipitated oxalate of lime, then ignite and weigh it, by which the oxalate will be converted into carbonate of lime. (ij) Th-> Lime Present as Phosphate. — The ammoniacal precipitate of the earthy phosphates is to be dissolved in strong acetic acid with the aid of he:it (if any portion remains undissolved, collect, dry, and calcine it, and having weighed it, estimate as pyro-phosphate), and to the solution oxalate of ammonia is added ; boil, and lay aside for 12 to 24 hours; collect the precipitated oxalate of lime on a filter, wash, dry, and ignite both the precipitate and the filter. As the object of this is to convei-t the oxalate into carbonate of lime (as in j), care must be taken not to heat too strongly; and, in addition, in case any caustic lime may have been formed, it is always advisable to moisten the precipitate with carbonate of ammonia before drying it at a moderate heat and weighing it. From the carbonate of lime thus obtained the amount of lime can easily be calculated [CaCOg (100) : Ca (40) = weight of carbonate of lime obtained : x\. (iij) The Maynesioj Present as Phosphate. — The filtrate and wash- ings of the last are to be evaporated to a small bulk, mixed with excess of ammonia, well stirred, boiled, and laid aside for 12 hours; it is then to be collected on a filter, washed with water contain- ing ammonia, dried, ignited to redness, and weighed. The ammo- niaco-magnesian phosphate is thus converted into pyrophosphate (MgoP207), from the weight of which the magnesia is readily obtained, (Mg.^PaOy (174) : 2MgO (80) = weight of pyrophosphate obtained : x!) (iv) Phosphoric Acid that was Combined loifh Lime. — The wash- ings and the filtrate still contain the phosphoric acid primarily combined with the lime. This is precipitated by adding a mixture of sulphate of magnesia, ammonium chloride, and ammonia, laying aside for 24 hours, then filtering and proceeding exactly as above. (1 : 0'216 = weight of pyrophosphate : x.) (d) The Total Phosphoric Acid Present. — This may be estimated 310 TISSUES, OFif^AXS, AXJ) REMAIXiyO SECRETIONS. directly (Chancel). Dissolve 1 gram of the ash in a little nitric acid, warming gently ; dilute with water, and add some baric nitrate and then some nitrate of silver ; shake well and filter. Pass a current of sul[)hnretted hydrogen through the filtrate, filter, and boil the filtrate for some time, until the hydric sulphide has been expelled. By this means any sulphuric acid and chloi'ine that may have been present are removed. Now add to the clear filtrate a solution of bismuthic nitrate, filter, and wash the precipitated bismuthic phosphate with boiling water ; dry it, and having detached it fi'om the filter, ignite both separately ; then weigh. (BiP04 (305) : H3PO4 (OS) = weight of precipitate : x. ) ('-) 27ie GarJwnic Acid. — Place 5 grams finely powdered and dried bone into a flask fitted with a desiccating tube filled with calcium chloride ; now suspend in the flask a small test tube containing hydrochloric acid, and weigh the whole apparatus. (Or the acid may be i:)laced in a stoppered burette fixed in the cork of the flask, and the drying of the gas effected by allowing it to escape through a U tube containing strong sulphuric acid.) The acid is allowed to flow slowly over the powdered bone, and the evolution of gas permitted to con- tinue until it is completed. When this is the case, by means of the tube (/, which has been stopped hitherto, force air through the appa- ratus, then weigh : the loss in weight = CO2 (1 part CO2 = 2-272 CaCOg). If greater accuracy is required, the flask is connected, as in an organic analysis, with a drying tube filled with calcium chloride, and this with a set of Liebig's bulbs containing strong caustic potash solution, to which is fixed a U tube filled with fragments of solid caustic last pieces of apparatus are weighed before and Fig. 23. — Carbonic Acid Al'PARATUS. In tlie flask a the weigheil, finely-powdered lione is; made into a nnid witli water. & is a small test tube containing the hy- drochloric acid ; c is a drying tube filled with fragments of chloride of calcium; iel, investing the crown and extending some way down the neck ; and cement, or crusta petrosa, covering the fangs. T. The Cement has the structure of bone, and in its compo- sition it is almost analogous thereto, its organic and inorganic constituents having the rehitive proportions of 30 : 70. Cement of Toath. Of ox (FitEMY) Of man (Bibka) Ash (containiii",^ an average of) 67"l per cent. 70'58 per cent. Calcic phosphate . . 60'7 ,, Magnesic „ . . 12 „ Carbonate of lime . . 2-9 ,, 312 TISSUES, ORGANS, AND REMAINING SECRETIONS. ir. Dentine. — This body, like bone, contains an animal matrix impregnated with earthy salts. Tlie animal matrix is of the nature of ossein, but the walls of the canaliculi appear to have special investments of a body resembling keratin or elasticin (Hoppe Seyler). Dentine is 4 per cent, poorer in water than bone, and contains 26 to 28 per cent, organic substances. Reckoning the carbonate and phosphate of lime together, HopPE Seyler gives the com- position as — Ca,„CO,6(PO0 . . 72-06 MgHPO, .... 0-75 Organic substances . . 27'70 According to Bibra, the following is the composition of the dentine of men and women respectively : — Adult woman Adult man Organic matter — ossein and vessels . 27-61 20-42 Phosphate of lime . . , , . 66-72 67.54 Carbonate „ . ... . 3-36 7-97 Phosphate of magnesia . . 1-08 2-49 Other salts (NaCl, &c.) . . 0-83 1-00 Fat . 0-40 0-.58 III. Enamel. — The ash averages 95 to 97 per cent. ; in the young infant it varies between 77 and 84 per cent. In the dog there appears to be no organic material at all. Its average composition may be thus stated : — Water and organic substances Calcic phosphate and fluoride Magnesic pho.sphate Calcic carbonate It is thus given by Hoppe Seyler : — Ca„C036(PO.) MgHPO^ . . . . Organic substances . 3-6 86-9 1-5 80 96-00 1-05 3-60 Enamel and Dentine compared — Ox (Aeby). Organic substance and water Inorganic „ In 100 parts a.sh — Calcic phosphate „ carbonate „ oxide Magnesic carbonate Calcic sulphate . Oxide of iron . Enamel 3-60 96-40 Dentine 27-70 72-30 93-35 4-80 0-86 0-78 012 0-09 91-32 1-61 5-27 0-75 09 0-10 :n:i CHAPTER XX. MUSCLE. We meet with two well-marked forms of this tissue in the l^ody — striated, such as constitutes the voluntary muscles of the limbs, and of which a special modification forms the con- tractile substance of the heart ; and non-striated, such as is met with in the uterus and in the muscular coats of the intestine. Without going into detail with regard to the complicated structure of striated muscle, it may be briefly stated that it is made up of fibres that appear to consist of a conjoined series of short tubes formed by the sarcolemma, and that these, according to some authorities, are further divided (Krause, &c. ) into an immense number of little superimposed compartments, in which are contained minute bodies named sarcous rods, of whose exact chemical nature we are ignorant, the rest of the compartment being filled up with a fluid plasma, that lies not onl}' among the rods, but is also accumulated at their ends. The rods in each compartment are arranged on the same level, so as to form a stripe that is doubly refracting, while the con- tractile plasma is singly refractiug. The narrow muscular fibres of the heart are made up of transversely striated, oblong, nucleated cells, which are fused together end to end ; while the unstriped muscle is composed of elongated fusiform cells with oval or strap-shaped nuclei which are united together in bundles. Properties. — In a state of rest the reaction of muscle is alkaline ; but in coagulated muscle the reaction is acid, the acid also increasing during contraction. The acid is paralactic, but possibly also acid potassic phosphate and carbonic acid may contribute to the acidity. This increase in the acidity, as well as the accumulation of the waste products, may be the cause of the muscular fatigue experienced after continued excessive exertion. But Astachewski has only been able to find lactic acid in muscle at rest, the acidity of the watery extract of the 314 TISSUJES, 01iGA^'S, .4.Yi) REMAINING SECRETIONS. mu;icles after treatment with alcohol, in the case of paralysed and resting- muscle, having been found higher by him than that of tetanised muscle. Warren finds that if the acidity of an untetanised limb be taken as 1, that of the tetanised limb will average 0*52. Pfluger explains this apparent paradox by supposing that two molecules of lactic acid condense into one with elimination of water, the acidity as measured by the power of saturating alkali being at the same time reduced to one-half. The density of muscle is about 1055 in mammals — that is, the mean density of the blood. The colour of muscle is apparently due to the haemoglobin contained in it independent of the blood ; but in addition there has been described a yellow colouring matter soluble in ether, aiid presenting two absorption bands coinciding with those of oxy haemoglobin, but not due to this body, as they are not alterable by the action of acids or of sulphuretted hydrogen (Stkuve). The name salmonic acid has been given to the red oily colouring principle of the muscle of the salmon, &c. (Fkemy); its existence, however, is doubtful. The sarcolemma is with difHculty soluble in acids and alkalies, and seems to be identical in some respects with keratin or elastin, but it is probably more correctly to be regarded as allied to collagen in its nature (Chittenden, &c.). Under the action of dilute hydrochloric acid the muscle fibre is split into transverse discs, while that of alcohol causes it to bn^ak up into hbrils. Changes occurring in Muscle. — Even in a state of rest certain chemical changes are taking place in muscle, differing only in degree from those occurring in a state of activity. The muscles also have the power of storing up oxygen while in a state of rest, particularly during sleep. During contraction the muscle (1) becomes acid, carbonic acid being set free, and possibly also sarcolactic acid, no im- raediate, increase, however, in the consumption of oxygen occurring, indicating the independence of muscular contrac- tion and immediate oxidation. This is owing to the oxygen stored away by the resting muscle. As PfljIger states, the oxygen helps to wind up tlie vital clock. J>ut the blood flow- MUSCLE. 315 ing away from an active muscle is poorer in oxygen and richer in carbonic anhydride than the same blood coming from a muscle at rest. In a given time, indeed, muscle work increases the absorption of oxygen and excretion of carbonic acid gas at the lungs. 2. Heat also is produced in nuiscular contraction, but this elevation of temperature really precedes the act of contraction and is not caused by it, for if work is effected by the contrac- tion part of the heat disappears. The heat is the result of certain chemical changes occurring in the muscle. 3. Decompositions of different kinds also occur in the pro- cess of contraction, some body or bodies soluble in water being converted into others insoluble in water but soluble in alcohol ; that is, tlteivatery extractives are diminished and the alcoholic extracts increased (Helmholtz), showing an augmentation in the kreatin, kreatinin, and xanthin, &c. 4. Some affirm that the proteids are slightly diminished and the sugars and fats increased (Eanke). This observation, however, has not yet been fully confirmed ; but it seems to be established that the glycogen of muscle is diminished by the act of contraction (Bkucke and Weiss), such a decomposition as the following, in which much energy is liberated, being probable : CJ[,o( )., + H,0 = C«H,.,0„ and (-\n,,0, -f GO^ ^ 6C0, + 6H,0. It is probable also that a slight increase occurs in the elimination of urea, but not an increase in any way proportional to the work done ; likewise an increased elimination of sulphuric and phosphoric acids in the urine, the acidity of that fluid also being said to be raised. But it must be confessed that of the exact nature of the changes little really is known. Hermann is of opinion that an analogy exists between ordinary muscular contraction and rigor mortis, and that in both cases a complex body, which he calls inogen, is split up into carbonic and lactic acids and a nitrogenous residue of the nature of myosin ; in the living body the myosin thus formed is redissolved as rapidly as it is generated, being reconverted, in combination with other bodies present, into the inogen, such a conversion of course not being possible in rigor mortis. In rigor mortis the muscle becomes more or less opaque, loses its elasticity, is firmer to the touch, and all normal muscle 316 TISSUi:S, ORGANS, AND liEMAINING SECRETIONS. currents have disaijpeared ; its reaction also is decidedly acid, altliougli it is frequently amphicroitic, sarcolactic and inosic acids being present, and an excess of carbonic acid being set free at the same time. A relationship appears to exist between the intensity of the rigor mortis and the amount of these acids formed. Some suppose, therefore, that these bodies result from the splitting up of a complex compound previously present. Eigor mortis, then, is characterised by the coagulation of the muscle plasma of the living muscle and by the appearance of sarcolactic acid. Chemical Composition. Analijses of Muscle (] JiDKA, iSCllLOSSBEK&EK, &C.' . Components in tlic 100 parts Pectora Man, £et. 5!) is major Woman, OBt. 36 JFeau of liuman ni iiscle Mean of mnscle of mammal Muscle of birds Muscle of fisli Muscle of frog Water .... 72-.56 74-45 73-50 72-87 73-00 74-08 80-43 Solids .... 27-44 25-55 26-50 2713 27-00 25-92 19-57 Coagulated albumins (myosin, &c.) and llieir derivatives ; sarcolemma, vessels, nerves, &c., insoluble in water . 16-83 15-54 16-18 15-25 17-13 10-13 Soluble albumins and albuminates ; hsemo- globin 1-75 1-9.3 1-84 2-17 313 3-61 1-86 Fat . 4-24 2-30 3-27 3-71 1-94 4-59 010 Gelatin 1-92 2-07 1-99 3-16 1-40 4-34 2-48 Kreatin — 0-22 0-18 0-33 — 0-28 Ash . 2-68 3-57 3-12 1-14 1-30 1-49 Non-striated muscle appears to have nearly always an alka- line reaction, and its ashes are richer in salts of soda than in those of potash. The analysis of non-striated muscle is thus given by Chittenden : — Water .... Solids .... Ash .... Albuminous Ijodics Ethereal extractives . Non-nitrogenous bodies Glycogen . Glycocin The Gases of Muscle. — These are in part dissolved in tlie muscle plasma, and in part combined with its salts. 79-60 to 8025 20-40 „ 19-75 1-26 „ 1-22 15-68 „ 15-04 0-33 „ 0-24 3-25 „ 3-12 2-13 „ l-'.tH 71 „ 039 MUSCLE. 317 CO, N O ]4'4 per cent. 4-y „ O-O'.l „ (SZUMOWSKI). By bringing living muscle into boiling water, and then pass- ing it througli air, and treating it with phosphoric acid, a mean of 7*2 percent. CO^ was obtained by Stirizing, of which one part was combined. But the amount of COo appears to vary according to the mode of preparation of the muscle, as when tetanised and quickly cooled it yields G-H per cent., but 13-5 per cent, when tetanised and cooled slowly ; only 2*7 per cent, when washed, 2 per cent, when warmed for sometime, and lo*4 per cent, when neither warmed nor washed. The solids of muscle vary on an average from 21 to 26 per cent, in mammals, and 22 to 28 per cent, in birds, and about 20 per cent, in cold-blooded animals. In mammals the solids, in addition to those tabulated above, may be thus stated : — Per cent. Per cent. Glycogen . . 0-4 to 05 Phosplioric aci( 1 . 0-3 to O-.-) Kreatin . 02 I'otash . 0-3 „ 0-4 .Sarkin . 002 Soda . 004 Xanthin and hv] )0- Lime . 001 xantliiu . . 002 Magnesia . . . 004 Taurin (horse) . . 007 Sodic chloride . 001 „ 0004 Lactic acid Tlic (lifT f( >n s f i f Oxide of iron npnts inav he . 001 „ UU03 irrnno-prl in tLro< groups : — I. Nitrogenous bodies— -rayosin, and two or more other proteids; extractives such as kreatin, sarkosin, sarkin, xanthin, and carnin. II. Non-nitrogenous bodies — inosit, fat, glycogen, &c. III. Inorganic bodies — phosphoric acid, potash, soda, mag- nesia, lime, &c. I. Nitrogenous Bodies. The living muscle contains a liquid, coagulable plasma which can be removed, and this on coagulating at ordinary tempera- tures separates into clot and serum, this clot (myosin') being the same body as is obtained from dead muscle by dilute sodic chloride solution ; myosin is not therefore present in the living muscle, only its factors, so to speak. By the action of acids tins body is further transformed into syntunin. The muscle 318 TISSUES, ORGANS, AND HEM AI NINO SECRETIONS. contains, in considerable amount, a body analogous to serum albumin, and coagulating at 75°; in very small proportion a solnlile proteid coagulating at 45° ; and a third proteid, a sort of alkali albumin, which varies in its point of coagulation (20° to 30°) according to the acidity of the serum. But it is possible that some of these may be derived from the lymph in the muscle. The gelatin of muscle comes from the connective-tissue elements present, such as the perimysium, sheaths of nerves, blood vessels, &c., although the muscle plasma may contain collagen (Hoppe Seyler). Fig. 2-}.— CliYSTALS OF KliEATIN AND KltEATINIX. (I, crystal? of krcatiii ; t, crystals of kreatiniu ; c, ci-j'Stals of chloride of zinc and kreutiiiin. A myosin ferment identical Avith the fibrin ferment of blood has been separated from frog's muscle (Michelsohn). The muscle plasma, myosin, and muscle serum have already been described (\)\). 107, 108). The Extractives. While these form 2 to 4 per cent., at least two-thirds of them are yet unknown. Among the nitrogenous extractives are found kreatin, sarkosin, hypoxanthin, xanthin, carnin, inosic acid, &c. (CN T. KnEATiN, CJT.NaO, + UA o'- ^a -I ^j"-'' , or 1 c/h.o.oh MUSCLE. 319 (NILNH.CN.CHs.OHaCOOH).— It is a very weak base, but it forms crystalline cotupouuds witli several of the mineral acids ; it also com- bines with mercuric chloride and nitrate ; its crystals appear as colour- less, transparent, rhombic prisms, but in the anhydrous condition it is white and opaque. Fresh muscle contains a mean of 02 jjer cent., or the solids of muscle a little more than 1 per cent. It is increased by muscular activity. Kreatin is sparinijly soluble in cold wnter, moderately soluble in hot water, less sohible in alcohol, and insoluble in ether. Preparation. — I . J Jub up pieces of muscle with fragments of glass, and digest the mass with twice its volume of alcohol in a water bath ; express the extract through linen, evnj^orate off the alcohol, and precipitate the watery extract with basic lead acetate ; through the filtrate from this last sulphuretted hydrogen is passed to separate excess of lead, and when the latter has been removed evaporate to a syrup, from which on cooling kreatin will crystallise out. To free it from the kreatinin that is generally comlnned witli it, treat with chloride of ziuc. 2. Rub up some Liebig's extract of meat with water and then with baryta water, filter, and remove excess of baryta from the filtrate by a current of carbonic acid gas ; after filtivition evaporate to one-twentieth its volume, and leave the syrup aside for several days to crystallise. The same process may be adopted with a watery extract of fresh meat when it has first been freed from albumin by boilin Q Sarkosin is procluced by tlie decomposition of NH^ ) ' kreatin, this liody splitting into sarkosin and nrea when boiled with baiyta water. Preparation. — A hot saturated solution of kreatin is boiled with ten times its volume of baryta water so long as any ammonia is evoh-ed, fresh baryta water being added from time to time. Then jBlter and precipitate the excess of baryta with carbonic acid. From the evaporated syrupy filtrate sarkosin will separate in a few days. The crystals are purified by dissolving them in excess of dilute sulphuric acid, and the solution evaporated to a syrup and well shaken with alcohol. Sarkosin sulphate separates as a fine powder, which is to be washed in cold alcohol, dissolved in water, boiled with baric carbonate till carbonic acid gas ceases to be evolved, filtered from the baric sulphate, and the filtrate evaj^orated to a syruj). Sarkosin crystals will sejDarate inside 24 hours. CafFein, when similarly treated, also yields sarkosin. Properties. — It crystallises in colourless rhombic prisms that are soluble in water, slightly soluble in alcohol, and insoluble in ether. It combines with acids, forming soluble salts ; its double salt with pla- tinio chloride crystallises in large yellow octohedi'a (C3H7NO2.HCI + PtCi4 + H20), and that with chloride of gold in rhombic tables (CaH^NOs-HCH- AuClg). With acetate of copper it gives a marked blue colour, forming a crystalline compound with this salt; it combines also with chloride of zinc and mercuric chloride. III. Sarkin, or Hypoxanthin (CsH^N^O), is found in muscle, generally in the proportion of about 0*02 per cent. ; it is also present in the spleen, liver, thymus, and in the blood and urine of leukaemia, generally accompanying xanthin. Preparation. — It is prepared from the mother liquor of the kreatin, which is diluted with water and then boiled with two-thirds its volume of a solution of cupric acetate. The sai'kin cupric oxide is washed in cold water, suspended in hot water, decomposed with a stream of hydric sulphide, and filtered hot. The sarkin separates on cooling. It can also be well pi-epared by adding gi-ulually to a boiling saturated solution of kreatin ten times its weight of hydrate of baryta ; the mixture is boiled so long as any ammonia is evolved ; filter, pass a current of carbonic acid gas through the filtrate, and filter again ; lay the last filtrate aside to crystallise. To purify it dissolve up the deposit in dilute sulpliuric acid, evaporate to a syrup, and add alcohol. The crystalline powder is then dissolved in water, warmed with carbonate of baryta as before, filtered, and the filtrate evaporated to a syrup and thr-n laid aside. MUSCLE. 321 Properties. — Sarkin crystallises in fine needles and is slightly soliil)le in hot water, Itut readily soluljle in the alkalies and in dilute hydrochloric acid. It combines with acids, bases, and salts; with silver nitrate it forms a crystalline compound wlien precipitated from its ammoniacal solution by means of this body (C5H2 Ag.2N40 + H.2O). This is a more insoluble salt than the corresponding one formed with xanthin. It^ hydrochloride is also less soluble than that of xantliin. It is not precipitated l)y ammonio-acetate of lead. Chemical Relations. — Sarkin is closely related to xanthin and uiic acid, being foi'med by the reducing action of sodium amalgam upon either of these bodies : C,H,N,03; C,H,N,0.,; C,H,N,0. (uric acid) (xanthin) (sarkin) IV. Xanthin (C-,H4N40.2). — Mixed with hypoxanthin it is met with in different parts of the organism, as in muscle, spleen, pancreas, and liver. Its formation seems to pre- cede that of uric acid, from Avhich it ^^1^ ^r::^ O"^-;:^ differs in containing an atom of oxygen ^^%^ ""^^ ^ /7V^/^ less; indeed, by reducing uric acid ^' 'J /j ^^ ^ ^^.^^^^^^ with sodium amalgam it can be ob- Z7 /\ ^-ci,<^ /7 ^-^ tained, or by the oxidation of sarkin. ^<=:> A ^^^ It has been found in urinary calculi. '^ Preparation.— It can be prepared ^'<'- 25-cr^YSTALs of xanthin-. - , ,. , 1 1 • 1 • ii To the left are pearly rhombic tables irom the yeJ low crust obtamed m the of th? sulphate. treatment of the extractives by dissolv- ing this up in dilute hydrochloric acid and slowly evaporating the solution. But it is best prepared from guanin (O^^H-.N ,0) by dissolving this body in strong nitric acid, adding potassic nitrite in excess, and then water until a yellow precipitate is formed, which is dissolved in boiling ammonia and sulphate of iron added until a black precipitate appears. The filtrate is evaporated, and the residue, after having been washed in cold water, is dissolved in boiling ammonia, filtered, and evaporated to dryness. Properties. — 1. It is white and amorphous, forming microscopic granules very slightly soluble in boiling water, insoluble in alcohol and ether, and forming soluble combinations with bases ; its solutions are precipitated by acids, with which it forms crystalline salts, and by the salts of copper, with which the pi^ecipitates are greenish. 2. Xanthin dissolves in boiling ammonia, and the sohition is precipitated by chloride of zinc, cadmic chloinde, and acetate of lead ; Y 322 TISSUES, ORGANS, AND REMAINING SECRETIONS. silver nitrate also throws down from this ammoniacal solution the gelatinous compound C5H2Ag2lSr402 + H20, If the xanthin is dissolved in some warm dilute nitric acid r.nd silver nitrate added, little flocculi will separate on cooling : C5H4N,j02 + AgN03. 3. Phosphomolybdic acid gives with it a voluminous yellow pre- cipitate soluble in dilute acids. 4. When evaporated to dryness with nitric acid a yellow residue is obtained, which becomes reddish yellow on the addition of soda, changing to a violet on heating. . V. Carnin (C7Hg]Sr403 + H20), — American extract of meat contains about 1 per cent, of this body, but it has not yet been found in fresh meat. Carnin has a pulverulent, chalky appearance ; it is insoluble in alcohol and ether, but soluble in boiling water, its solution beinj; pre- cipitated by subacetate, but not by the neutral acetate of lead. It com- bines with warm hydrochloric acid, its hydrochlorate, 07113X403. HOI, forming brilliant needles, and combining readily with platinic chloiide with the production of a double salt ; with silver nitr-ate it also gives a white flocculent precipitate, {07H8N403)2.AgN03, which is insoluble in ammonia and nitric acid. Like sarkin, carnin is an imperfectly oxidised decomposition product. O7H8N4O3 = O5H4N4O (sarkin) + O2H4O2 (acetic acid). It may be converted into sarkin by the action of nitric acid or bromine. Preparation. — It is prepared from Liebig's extract of meat by boiKng this with seven times its weight of water, precipitating the solution with baryta water, carefully avoiding excess ; filtering, adding subacetate of lead to the filtrate, and separating the pi^ecipitate that forms, which consists of a combination of carnin and plumbic oxide. Suspend this compound in hot water and decompose it witli a current of hydric sulphide, filter, and concentrate the filtrate by evaporation. The coloured deposit is to be treated with silver nitrate, and, to remove any silver chloride that may form, wash the precipitate Avith ammoniacal water, and then with pui'e water ; sus- pend again in water and decompose with hydric sulphide, filter, and digest the filtrate with animal chai^oal. Fi-om the clear filtrate, when concentrated, carnin is deposited. VI. Inosic Acid (C|o1Ii 1X40,1) has not as yet been satisfactorily determined in human flesh, but it forms about 001 per cent, of tlie muscle of cats or rabbits. lis alkaline salts form fine needles easily soluble in water, but MUSCLE. 323 insoluble in alcohol, audits solutions give amorphous precipitates with copper and silver salts. VII. The proportion of xanthin, as well as of uiic neid, is veiy small, and the same may be said for the pepsin and ptjjaJin ferments that are said to exist in muscle. Taurin has been found in fish and horse flesh, and leuc'in in horse flesh. GuANiN (C.-,H5lsr50) was originally obtained from guano, in which it exists in the proportion of about i to | per cent. ; but it has also been found in small quantities in the liver, pancreas, and muscle. It forms a white amorphous powder, easily soluble in potash, soda, and the mineral acids, but insoluble in water, alcohol, ether, and ammonia. It is prepared by boiling Peruvian guano with dilute milk of lime so long as the filtrate is coloured ; the residue is then extracted with a boiling solution of sodic carbonate until the sodlc extract is no longer precipitated with hydrochloric acid; this extract is then treated with excess of acetic acid, and the precipitate, which consists of guanin mixed with uric acid, is digested with boiling dilute hydro- chloric acid, the solution filtered, and the guanin precipitated from the filtrate with ammonia To remove the uric acid completely repeat the digestion in the hydrochloric acid and the precipitation with ammonia. By the action of nitrous acid guanin is converted into xanthin, C5H5N50 + HNOo = C.3H4N402 + Il20 + N2; and when a hydro- chloric acid solution is treated with potassic chromate it is decomposed into guanidin, parabanic, oxaluric, and oxalic acids, and v;rea, Urea is present in muscle only in diseased conditions, as in urajmia and cholera. II. Non-nitrogenous Bodies. 1. Tnosit, or Muscle Si(,gar (see p. 81). 2. Ghjco(je/)i, &c. — The amount of this is less in tetanised than in resting muscles, less also in the muscle of the heart ; but the quantity present depends somewhat on the natvn-e of the food, and on age, for more glycogen is proportionally present in young than in old muscle. In the fresh muscles of frogs from 0'3 to 0'5 per cent, can be extracted, and in rabbits 04 to 05 per cent. As a diastatic ferment is also present in muscular tissue, it is probable that the fermentable sugar found in muscle after death is derived from the glycogen. 3. Fats. — These belong iu part to the muscle substance, but also, particularly the glycei'ophosphoric acid and cholesterin, to the nerves present in the muscle. Volatile fatty acids can likewise be extracted. Y 2 324 TISSUES, OEGANS, AND BEMAINING SECRETIONS A coiist:int constituent is pnralacfic nciJ, wliicli is probably combined wit! I some of the alkalies of the muscle. 7\> prepare paralactic acid from muscle, dissolve Liebig's extract of meat in four parts lukewarm water, and then with constant stirring add eight parts alcohol (90 per cent.) After standing some time decant the clear supernatant liquid ; distil off the spirit, and having acidified Avith dilute sul])huric acid shake iip with ether. Distil the ether extract, precipitate with plumbic carbonate, filter, pass sulphuretted hydrogen through the filtrate, and after having boiled neutralise with carbonate of zinc : zinc lactate is formed. Evaporate until on cooling crystals begin to sepai-ate ; now treat the residue with five times its volume of alcohol (90 per cent.) After some time collect the fine crystalline precipitate on a filter, wash with alcohol, and then dry it. To separate some lactate that still remains in the alcoholic filtrate, evaporate the latter, dissolve up the lesidae in water, and precipitate the solution several times with alcohol. By decomposing with hydric sulphide the paralactate of zinc thus ob- tained, filtering, evaporating the filtrate to a syrup, and then dis- sohdng it in pure ether, the zinc can be separated by filtration. From the last filtrate the ether is distilled off" and the residue dried III. Inorganic Constituents. 1. Water. — Its average is about 75 per cent., being greater in cold- than in warm-blooded animals ; it is also more abundant in tlie muscles of young beasts, diminishing towards adult life and increasing again in old age; the muscle richest in water is the continually acting heart. A proportion also seems to be maintained between the water of the blood and that of the muscles, for with a thin blood the water of muscle is propoi'tionally greater ; and the same occurs in chronic wasting diseases. In great thirst the water of muscle is said to diminish. In females and weak males the water is more abundant. Indeed, age, sex, race, activity, and altei'ation of diet exercise a marked influence on the chemical composition of muscle, particularly in the amount of water. 2. Salts. — The ash of muscle is characteiised by the preponderance of potassic salts and phosphates, these forming nearly 80 per cent., and by its poverty in soda salts and chlorine. The salts of magnesia are three times as abundant as those of lime, and alkaline sulphates arc present only in small amount. In dried flesh there is about S'O per cent, of ash, in fresh muscle r07 per cent., and in boiled flesh 1 per cent. (Liebio). MUSCLE. 325 Boiling produces a great change in the salts. In the following table it will be seen how much of these salts can be tlius extracted (Keller) : — Phosphoric acid Potassium Potassic chloride . Earthy and iron oxides Sulphuric acid In the soup Remaining in the flesh Per cent. Per cent. . 26-21 10;3G . 35-42 4-78 . 11-81 . 3-l;-3 2-54 . 2-95 82-57 17-(i8 Keller therefore gives this percentage composition of the ash of invscle : — Phosphoric acid . . 36-60 Iron and earthy oxides . 5-69 Potassium . . -10-20 Sulphuric acid . 2-95 Potassic chloride . 11-81 The phosphoric acid is combined with the potassium, and with the earthy and iron oxides in part, and the sulphuric acid is probably present in great part as potassic sulphate. Pathology. — ]Muscle is liable to dififerent degenerations, particularly fatty, during and after certain diseases and in old age. In many fevers more or less of a degeneration occurs. In fatty degeneration Liebig has found as much as 49 per cent, of fat. In chronic alcoholism the inosit is said to be increased. Urea, uric acid, and fats have also been found greatly augmented after different diseases. In cholera urea is met with in the muscles, principally those in which the most cramps have occurred, and this is possibly due to the want of a solvent medium to remove it. Sources of Muscular Energy. — Liebig was of opinion that the proteids were the exclusive source of muscular energy, and that the urea excreted, derived from this consumption of nitro- genous material, was proportionally increased. But the experi- ments of most recent observers prove this theory to be incorrect (Parkes, Voit, E. Smith, Fick, &c.), and show that the oxida- tion of the proteid material represented by the m-ea excreted is much less than that required to accomplish the work done. Parkes, indeed, found no marked increase in the urea as the result of muscle work, often rather a diminution in its amount 320 TISSUES, ORGANS, AND REMAINING SECRETIONS. duriug the period of activity, but a slight subsequent increase in its elimination. Thei'e is no doubt, however, as to the increased elimination of carbonic acid gas at the lungs produced by muscular exercise. A man, for example, at rest consumed in the twenty- four hours 708 grams oxygen, and produced 911 grams carbonic anhydride ; but when doing work the numbers were 954 grams oxygen and 1,284 grams carbonic anhydride. The m-ea excreted in the same time in each case amounted to 37*2 grams during the day of rest, and 37 grams during the day of activity (Pettenkofer and Yoit). The source of the energy may therefore be looked for in the non-nitrogenous foods (chiefly the carbohydrates), the muscle only acting as an apparatus in which the potential energy of these bodies becomes kinetic. Helmptoltz has arrived, by cal- culation, at the conclusion that in the human organism one- fifth of the potential energy of the material thus consumed is ccnverted into kinetic energy — which is about twice the amount of mechanical work that can be obtained hy the instrumentality of the steam engine. (See also under Urea, pp. 429, 431.) GENERAL ANALYTICAL METHODS {after Kussel, StADELEK, cC'C.) A. I. Preparation of Watery Extract. — Kill a dog or cat by decapitation, open its abdomen rapidly, and having inserted a cannula ioto its aorta, wash out the vessels with sodic chloride solution (10 per cent.) ; then cut out the thigh muscles, and mince them up finely with the help of a sausage machine. The mass is next covered with distilled water, stirred well, and filtered after twenty minutes or so through linen, compressing to assist the filtration. II. If the extract has been made rapidly, then test a small portion as follows, by which means three albumins at least are identified : — 1. Warm a little to 20° to 30°; it will become acid, and de- posit a flocculent precipitate ; hut if tlio juice is too acid no pi-ecipit;ite is tlius obtained. 2. Adda few drops of dilute acetic, lactic, or liydrochloric acid, and note the formation of a prcci[)itate ; separate this M USCLE. 327 potassic ulbuniinato by filtration, warm up the filtrate to 47°, and a precipitate is obbiiued ; filter and wiirm the filtrate to 75°, and a second precipitate appears. 3. To a third specimen add a little sodic phosphate solution, and then the dilate acid, when it will be seen that no pr(.'ci])itation occurs, indicating that the albumin thrown down after acidif)'iug as iu 2 is an alkali albuminate. III. Separation of Soluble Albumins. — The filtrate obtained in I. is to be slightly and gradually acidulated with dilute hydrochloric or acetic acid and boiled : any soluble albumins present are thrown down. The filtrate is to be used in the sub- sequent experiments. 1\. Precipitate of Phosphoric, Sulphuric, and Uric Acids, of Hypoxanthin, and of the Kreatin and Gelatin in part. — These bodies are precipitated by the addition of haryta ivater to the filtrate of III. ; filter. (a) Boil the precipitate some time with a dilute solution of caustic 2'>otash, filter, and acidulate the filtrate v,'ith hyfb'ochloi-ic acid; if a precipitate appears remove it by the addition of a few drops of caustic potash, and then add amnionic chloride ; uric acid is pre- cipitated as urate of ammonia. Filter after some time. (b) The filtrate from the baryta precipitate is evaporated over a water bath, and any scum that forms on its surface is to be removed and added to the precipitate a ; when a syrup has been formed leave it aside under cover : little prisms of kreatinin will be deposited. (Some- times little semicrystalline yellow spheres of leucin may be deposited here.) Separate the crystals and add alcohol to the mother liquor until a slight cloudiness appears, then lay aside in a dry place under cover : needles or crystalline grains, consisting of potassic or baric inosate, magnesic j^^iosjjhate, or kreatin will form. Dissolve the deposit in warm water and add baric chloride ; baric inosate is precipitated. Filter, boil the pi'ecipitate with a little dilute suljihuric acid, filter, concentrate the filtrate, and add alcohol ; iaosic acid is deposited. Mix the filtrate from the baric inosate witli alcohol ; two layers are generally formed : decant the one from the other; the lower is generally syrupy. If it presents a gelatinous or membranous pre- cipitate, separate it by filtration, redissolve the precipitate in water, and reprecipitate Avith alcohol ; this precipitate is generally dextrin or (jhjcoijen. To the syi'upy liquor, after the sepai-ation of the gelatinous pre- 328 TISSUES, ORGANS, AXD liEMAiyiXG SECPxETIOXS. cipitate when present, add an equal volume of ether ; two layers will generally torm, as before : the lower one may contain lactates, volatile fatty acids, and inosit, and the upper kreatin, kreatinin, and some- times leticin. Decant or separate these layers by means of a suction tube. Concentrate the upper layer and leave it aside to crystallise ; if little lamellae ai^e formed add some cold alcohol, collect on a filter, ■wash them there with moi-e alcohol, and then dissolve them in some boiling alcohol ; when the alcohol cools kreatin separates, the kreatinin remaining in solution. The lower stratum formed by the addition of the ether is syrupy ; add sulphuric acid in excess to remove the baiyta, filter, and distil the filtrate : the volatile fatty acids pass into the distillate, while the residue contains sarcolactic and succinic acids, from which they can be removed by treating it with ether. Now add alcohol to the residue left by the ether until a precijiitate appears ; this consists generally of crystals of sulphate of potash mixed with inosit, if this body is originally present. B. The extractives may also be separated as follows (Stadeler) : — • (rt) lleduce the muscle to small fragments and digest with spirit for some time, warm, and then exj^ress ; digest the residue for several hours with water at 50° ; express a second time, and unite the two extracts. Next distil off the spirit, and filter from the deposited albumin.- Reduce the filtrate to a small volume by evaporation, and add neutral acetate of lead to complete precipitation ; filter, and add basic acetate of lead to the filtrate; lay aside for 12 hours, to allow the precipitate to settle, and filter again. To the last filtrate add excess of mercuric acetate, and after 6 hours or so collect the pre- cipitate on a filter. Treat the filtered liquor with a current of suli)huretted hydrogen, remove the precipitated sulphide, reduce the clear filtrate to a small volume without letting it become syrupy; la.stly, spread this concentrated liquor in thin layers in a series of shallow vessels, and complete the evaporation at a temp, between 40° and 50° : an abundant precipitation of kreatin occuis. (b) The lead precipitate obtained above is to be suspended in water and decomposed with hydric sulphide ; xanthin and inosit aie present in the filtrate. Boil the latter with acetate of meicury, which throws down the xanthin ; collect the precipitate, wash it, and then suspend it in water, where it is to be decomposed with a current of hydi-ic sulphide; filter, and by evaporating the filtrate the xanthiri will ciystallise out in yellowish crusts. (c) The mercuric precipitate is suspended in water and decom- posed as before with sulphuretted hydrogen ; the filtrate contains 3] USCLE. yL>0 xanthin and sarkin. Eviiporate to a small bulk and add ammonia in excess, and then silver nitrate; collect the precipitate, wash it with ammoniacal water and afterwards with distilled water, then piei-ce the filter and wash down the precipitate into a small flask, where it is to be boiled with sufficient nitric acid (>;p. gr. I'l) to make a complete solution. After it has stood about 6 hours filter and collect the combination of sarkin and oxide of silver that has been deposited; to the tiltrate add ammonia in excess, and a yellowish flocculent precipitate is obtained of a combination of the same oxide with xanthin. C. Liebig's extract of meat may be advantageously used for the jH-ejiai-ation of most of the extractives (after Bruktox), 1 , Make a watery extract of a large spoonful or so of the extract, boil it quickly in a large flask, and filter through linen to remove the coagulated albumin ; let the filtrate cool, and add acetate of lead solution to complete precipitation, but a\oiding excess, and collect the 23recipitate. A. The Lead Precipitate. — (a) Suspend it in water, and pass a current of sulphuretted hydrogen through the liquid; filter and con- centrate the filtrate on a water bath; crystals separate out gradually. Filter after some hours, and wash the collected crystals of uric acid with water and then with spirit. {b) The Jiltrate is to be evaporated to a small bulk, its own volume of alcohol added to it, and gently warmed if a turbidity shows itself. Lay aside for several days, and inosit may ciystallise out ; if no crystals appear add ether ; if crystals ai"e still absent evaporate nearly to dryness, and after the addition of a drop of nitric acid complete the evaporation ; moisten the residue with calcic chloride solution, and on again evaporating to diyness a rosy red spot will indicate inosit. B. The Filtrate from the Lead PrecipitaJ.e. — Precipitate any lead present with sulphuretted hydrogen and filter. (rt) The filtrate is to be concentrated to a thin syrup, and then laid aside for several days. Ciystals of kreatin will separate ; decant the supernatant liquid, and to jjrecipitate the rest of the kreatin add to it 2 or 3 times its volume of alcohol (68 jier cent.) Collect all the crystals on a filter and wash them with spirit, then dissolve them in a little hot water, and on the solution cooling transparent oblique rhombic jirisms of kreatin will be obtained. (h) The alcoholic filtrate from the precipitated kreatin is to be evaporated to remove the alcohol, next diluted with water, ammonia added, and then an ammoniacal solution of silver nitrate : sarkin or hy2)oxanthin is thrown ^ovna. as a flocculent precipitate, which is to ,330 TISSUES, ORGANS, AND REMAINING SECRETIONS. be allowed to subside, and after having been washed several times by decantation with water containing ammonia it is to be collected on a porous filter and again washed ; now, making a hole in the bottom of the filter, wash the precipitate into a small flask with nitric acid (sp. gr. I'l). The flask is next to be boiled, and more nitric acid added, if necessary, to efiect complete or nearly complete solution. Transfer the clear solution to a beaker, where it is to stand for several hours, when a double salt of silver and sarkin will crystallise out. Decant the supernatant liquid (c), and, having washed the crystals with ammonio-nitrate of silver, susj)end them in water, and decomj)ose them with a current of sulphuretted hydrogen. Filter, and evaporate the filtrate : sarkin crystallises out. (c) To the decanted liquid add ammonia in excess, and a double salt of xanthin and silver nitrate will fall as a flocculent precipitate ; this, after having been washed by decantation, is to be suspended in boiling water and decomposed with hydric sulphide. The filtrate, when evaporated, gives a scaly film of xantliin. CHAPTER XXI. NER VK There is still much doubt and uncertainty, as well as differ- ence of opinion, as to the true chemical constitution of nerve substance, particularly as to which are real nerve con- stituents and which only decomposition products or mere mixtures. With this very vexed and complicated question I shall try to deal as clearly and yet as briefly as possible. Histologically the nervous tissues consist of nerve cells, nerve fibres, and of a supporting framework that may present itself as white fibrous tissue peripherally, or as the retiform neuroglia throughout the nerve substance. The nerve cells are little masses of j>rotoplasm, more or less irregular in outline, and provided with branching processes, each also possessing a large, well-marked nucleus and nucleolus. The proto- plasm is granular around the nucleus, but striated towai-ds the periphery. Of the processes given off" all branch, with the exception of one, which is usually thicker than the rest, and said to be con- tinuous witli the nucleus, the so-called axis-cylinder process of Deiters. These nerve cells generally lie in groups, as wc see in the NERVE. .331 anterior horns of the grey substance of the spinal cord, or in layers, as in the grey substance of the cerebrum. The oierve Jibrih (1) with Avhich these cells ai'e connected are generally either directly or indirectly associated together so as to form naked bundles (2), which are to be found as such in the grey matter, or invested with a medullary or myelin sheath (3), as in the white substance of the nerve centres ; or cov'ered with a fibrous sheath alone (4), as in the sympathetic nerve fibres ; or provided with the double investment of medullary sheath, and outside this the fibrous or primitive sheath (5), as in the ordinary peripheral nerves of the body. A nerve, it may be said, is formed of one or more bundles of the last two kinds of nerve fibres associated together in varying proportions. The myelin is half fluid in the living nerve ; it swells up in water and is soluble in alcohol, ether, and spirits of turpentine, and consists of cholestei'in, lecithin, cerebrin, albumin, and some fatty bodies. Osmic acid stains the myelin sheath black, and sulphuric acid gives it a reddish tint, while the axis cylinder reduces chloi"ide of gold solutions, is stained red by carmin, and is dissolved by ammonia. The term grey substance is applied to the periphery of the brain, the central mass of the spinal cord, and to the ganglionic masses scattered at the base of the brain, as w^ell as elsewhere in the body. This grey substance consists essentially of the nerve cells, w^hile the white substance, that as a rule forms the great mass of these centres, is made up of fibres. According to Meynert a vertical section of the cerebrum presents 5 layers — (1) a connective-tissue layer on the surface, very thin in man and the higher animals; only very few nerve elements are present ; (2) a narrow layer of snv 02 pyramidal cells closely arranged ; (3) a broad vertically striated band, in which lie large and small pyramidal cells, giving oflf numerous ramified branches ; (4) a layer of granule-lihe corjjuscles ; (5) beneath this a layer twice as broad, with large sjyindle-shajjed cells scattered thi-ough it. The vessels as well as the ganglion cells are surrounded by lymph spaces (His), and the ai'teries are further provided with a lymph space between their tunica adventitia and media (Virchow, Robin). The foliated grey sitbstance of the cerebellum has also (1) a layer of the nature of connective tissue on the surface, intermixed with some delicate nerve fibrils ; beneath this a (2) roio of ganglionic flask- shaped cells of large size, which communicate by latei^al processes, and send off processes outw^ards and inwards, and then (3) a thick nuclear layer or zone of small round cells presenting a granular appearance. 332 TISSUES, ORGAXS, AND REMAINING SECRETIONS. The Grey and White Matter. — There is much difficulty in making a complete separation of the grey and white matter. In the case of the cerebrum the proportions of these two con- stituents have thus been given by Danilewsky : grey, 37"7 to 39 per cent.; the white, 62*3 to 61 per cent.; and the super- ficies of the grey as 1,588 to 1,692 cm. Chemical Composition. — A close analogy appears to exist between the composition of an egg and of the brain substance ; in both there are the same richly phosphorised compoimds, albuminates, and proteids, also cholesterin, and excess of phos- phates and potassic chloride. The chief constituents vnll he first suonincwisecl, and then the more important of them considered in detail. 1. The Water is very variable in amount, differing in different parts and increasing slightly with age. In general where the phosphorised fats are most abundant the water is in smaller proportion. Mean Percentage of Water. Per cent. In the whole brain . . . . 71 to 83 ,, grey substance of brain . . 8i „ cerebellum . . . . 77 „ 80 „ medulla oblongata ... 74 „ spinal cord .... 72 „ white substance of brain . 69 In nerves 72 2. Albuminates. — Chiefly potash albuminate, also a globulin- like body corresponding to myosin, which is soluble in sodic chloride solution (10 per cent.) and precipitated by saturation with the same salt. There is in addition a proteid body, jjrobably derived from the grey matter, which is soluble in water and coagulates at 75°. 3. Albuminoids. — These form 7 to 10 per cent, of the fresh tissue of the brain, and somewhat more than half the dry residue of the grey substance, but only about a quarter of the white. Among these albuminoids nncltin is described as present (Jakscu) in the proportion of 0*14 per cent. (Geoghegan) ; but some chemists regard it as an impure albuminous sub- stance (Kingzett). 4. Substances soluble in Ether. — In white matter these ;mioniit to 15 to 17 ])c-r cent,, and in grey to 4 to 7 percent. NER VE. Ethereal Extract (BiBRA). 333 Comiioniid Brain Spinal cord Nen-es Woman, ajt. 40 Man, set. 36 Man, set. 39 Cerebrin . Cholesterin Fats Phosphorised fats . 20 to 21 30 „ 33 50 „ 40 306 32-8 37-6 23-7 5t-2 22- 1 3-40 0-8S 94-<»7 0-75 The medulla oblongata and the spinal cord yield the most ethereal extractives, the corpora striata and optic thalami the least ; but the age of the nerve substance affects this con- siderably. The spinal cord seems to contain less phosphorus than the cerebrum, and the grey substance of the latter more than the white. The brain of the new born contains much less ethereal extract than the same organ in the grown animal, but its water is more abundant ; or, in other words, the embryonic brain is much richer in water and poorer in cholesterin, &c., than the developed brain. Further, we find that the lower a mammal stands in the animal scale the richer is its brain in water and the poorer in ethereal extract (chiefly cholesterin and lecithin), and accordingly the nearer does it approach to the embryonic brain, whilst the higher the animal's position the poorer is its brain in water, and the richer in the ethereal extract. Some of the constituents remoA'ed by the ether are probably com- pounds chiefly derived from retrogade metamorphosis, and, as this is possibly most active in the highest brains, we can readily understand why the amount of ethereal extract in- creases in brains of higher development. That it is indicative of activity may also be seen from the fact that the very active medulla oblongata and the continuously active spinal cord are. poorer in water and very much richer in ethereal extractives than the brain substance itself. In the case of cholesterin also it has been shown (Flint) that the blood of the carotid artery is poorer in this body than that of the internal jugular vein. Among these extractives, in addition to those already given in Bibka's tables, there are neurin, lecithin, and iDvotagon', 334 TISSUES, ORGANS, AND llEMAINI^G SECRETIONS. of which some, like lecithin, contain phosphorus ; others, like cerebrin, are devoid of it. 5. Watery Extractives. — Of these there are xanthin, hypo- xanthin, kreatin, inosit (ox brain), sarcolactic and succinic acids, and sometimes leucin and iiric acid or a body resembling it. Many of these extractives, it is worth noticing, are also found in muscle, indicating a parallelism in their tissue changes ; they are all products of retrograde metamorphosis, but the leucin and uric acid are said only to be present in diseased conditions. It is probable that the kreatin, inosit, xanthin, sarkin, and lactic acid are derived chiefly from the grey substance. 6. Salts. — Fresh brain yields an average of 0*57 per cent, of ash (Geoghega^), which consists chiefly of potassic chloride and sodic phosphate with a little potassic and magnesic phos- phate, sodic carbonate, and potassic sulphate. The solid re- sidue of the grey substance contains about 0-63 per cent, more phosphoric acid than that of the white. The phosphoric acid appears to be increased by brain work, but this is doubtful, for it is possible that while the total phosphoric acid remains constant the alkaline phosphates may be increased and the earthy phosphates diminished. The urea and carbonic acid are also said to be increased by brain work or prolonged nervous excitation, the temperature also being raised (Davy). As abnormal constituents we may find m-ea and leucin in excess, as also excess of fats. TJltimate Analysis. I. Fresh Cerebrum— Ox (Petuowski). Grey matter. Wliito. Per cent. Per eeiit Water .... 81-GO 68-351 Solids .... 18-40 HI -05 Solids in the 100 parts- Albumin and gelatin . .5r,-.37 to 2-1-72 Lecithin . 17-21 „ 0-no Cholosterin and fats . 18-08 „ 51 -'.n Cerebrin .... 0-5:5 „ '.J-5i Substances insoluljlo in anhydrou s ether .... 0-71 „ .3 .It Salts l-5o „ 0-57 NERVE. 335 II. Mean Conij/osif ion —Chlci Constituents (after MOLESCHOTT). Brain. Spinal cord. Nerve.e. Per cent. Per cont. Per cent. AV.atcr 81-43 G8-.-)8 57-U7 Albuminous bodies . , 8"C3 7'49 Ethereal extract (fat, ccrc- brin, cholestcrin, &c.) . 8-07 30-02 2211 Salts 0-70 0-36 0-8.5 rotassic phosphate . .0-27 0-17 0-18 Sodic „ . . 0-23 0-08 0-13 Calcic „ . .0-12 0-07 0-19 III. The Axh — Analysis after the Separation of tlie Lccitliin, kc. (Geoghegan). Percentage in fresh brain Potassic chloride .... 0-277 Sodic phosphate .... 0221 rotassic „ .... 0047 Sodic carbonate .... 0044 Magnesic phosphate . . , 0-030 Potassic sulphate .... 0024 Calcic phosphate .... 0-003 Breed only obtained 0-027 per cent, of asli, of which potassic phos- phate constituted r)5-24 per cent., and .sodic phosi:)]iate 22-93 per cent. SciiLOSSBERGER found 1 per cent, in the grey substance of a calf's brain and I'lG per cent, in the grey matter of a human brain (set. 75). Difference between the Grey and White Substance Chemically. — Of the solids (1) the albumins and neui'oheratin form more than half the grey substance and only about one-fourth of the white. (2) On the other hand, cholesterin and fat constitute more than half the dry mass of the white and about one-fourth of the grey ; so that the chief constituents, so flir as quantity is concerned, are water and albumins in the grey, and water, cholesterin, and fat in the white substance. (.3) In addition, the grey contains about twice as much lecithin as the white, but less cerebrin. (4) The grey is richer in mineral constituents than the white. The ash of the grey substance is alkaline, and poorer in phosphates (Schlossberger) ; but, according to Petrowsky, the solid residue of grey substance contains 0'629 per cent, more phosphoric acid than that of the white. (5) The grey substance is weakly acid, containing lactic acid, the acidity increasing after death ; the white substance has a tim Tissui:s, ougans, and eemaininct sechetioxs. neutral or slightly alkaline reaction, and is not altered by the occurrence of death (Gscheidlen). I. LECITHIN, C.^H.oNPO,, or C.^Hg.NPOg.— This body is present in nerve tissue, particularly the grey substance ; also in yolk of egg, semen, blood corpuscles and serum, milk, and bile, &c. Preparation. — 1. Digest the yolk of egg with ether, and when the residue has lost its colour it is treated with absolute alcohol, and the alcoholic extract filtered ; the filtrate is cooled to —10°, when a solid body separates, having the composition C44HygNP09 ; while if the filtrate is evaporated in vacuo a body having the composition C44H90NPO9 is obtained. This last corresponds to the lecithin of the brain (Diakonow). Or, instead of cooling down the alcoholic extract, an alcoholic solution of platinic or cadmic chloride may be added, whicli precipitates the lecithin ; the yellow pi-ecipitate obtained, after having been repeatedly dissolved in ether and leprecipitated by alcohol to purify it fiom fatty matters, is decomposed by passing sulphuretted hydrogen through its ethereal solution. It is then filtered and the filtrate evaporated, when chlorhydrate of lecithin remains behind. This may be again dissolved in alcohol and ether, shaken up with oxide of silver, filtered, and after the separation of the dissolved silver by hydric sulphide filtered afresh and evaporated. 2. It may also be prepared from the brain suhstance. Separate the membranes and vessels from fresh brain, and rub the latter into a paste in a mortar ; then digest it with a large excess of alcohol, and let it stand for 3 or 4 days, rubbing it up from time to time. Filter and add to the filtrate platinic chloride and a little hydrochloric acid. Collect the yellow flocculent precipitate on a filter, dissolve it in ether, and decompose it with a current of hydric sulphide; filter again and evaporate, when a waxy mass will be obtained. General Characters and Relations. — The lecitliins play the part of fatty bodies, and are readily decomposed. For example, if an alcoholic solution of lecithin is poured into boiling baryta water, a precipitate of phospho-gly cerate, oleate, palmitate, and stearate of baryta falls, while neurin is set free, C^^HgQNPO^ + 311/)=: C.5H,,P0r, fglycero-phosphoric acid) + C.H,.N05 (neu- rin) + 2(C,j^H3/J„) (stearic acid). An ethereal solution is split into neurin and distearyl phosphoric acid by the action of dilute sulphuric acid. Lecithin may therefore be regarded as a glyceride in which a phosphoric acid residue replaces the fatty acid radicle — NER VE. 337 fO(C.3H3,0) C3H, 0(C,JT3,()) lo ro.oii OC2H4(CH3),N.OH. In other words, it is a combination of clistearyl, dipalmit}'], or oleopalmityl glycero- phosphoric acid, OjHgj |N(CH3) lOPO CgH^.OH, to.OH with neurin, this last body being a hydrate of trimethyl |(CH3)3 hydroxylene ammonium, NC^H^.OH (Diakonow). (oh. Properties. — The lecithin of brain forms a colourless, slightly crystalline powder, often, however, presenting itself as a white, waxy, hygroscopic solid, that is easily fusible, insoluble in water, but swelling up in it like starch and forming an emulsion which gives a flocculent precipitate with sodic chloride. It is slightly soluble in cold alcohol and ether, but easily soluble in the same fluids when warm ; also soluble in chloroform and benzole. Lecithin is readily decomposed, this occurring spontaneously at 70°, and even at ordinary temperatures the same occurs when it stands some time. Its alcoholic solution acidulated with hydrochloric acid gives with platinic chloride a yellowish floccu- lent precipitate of the double salt ; and with cadmic chloride a white flocculent precipitate. II. PROTAGON (Cerebrote). Preparation, — The brain is washed by injecting water thi-ough the carotids ; it is then bruised and agitated with a mixture of ether and water kept at a temp, of 0°, and frequently renewed. A Icohol is then added to the extract thus obtained, and digestion is allowed to go on some time at a temperature of 45° ; filter next, and cool the filtrate to O''. Flocculi will thus be obtained, which are to be collected on a filter, washed in ether to free them from cholesterin, the mass then dried in vacuo and redissolved in alcohol at 45°, filtered, and reprecipitated by reducing the temperature very slowly to 0°, This treatment is lepeated several times, and a fine crystalline white fiocculent precipitate is obtained (Liebreich). Relations. — Protagon forms the principal part of the white z 333 TISSUES, ORGAXS, AND REMAINING SECRETIONS. substance of Schwann ; it may be regarded as a glucoside, and lecithin as one of the products of its saponification by water. It was first described by Liehreich, and closely resembles Fremy and Bibra's cerebric acid and Gobley's cerebrin ; for a long time past it has been regarded as a mixture of lecithin and cerebrin, but some recent investigations appear to point to its chemical identity (GtAMGEe), although the evidence on the other side is apparently strong. Characters. — The formulae CjigH^^jN^PO.^g (Liebreicu) and ^100^305^5^^35 (Gamgee, &c.) have been assigned to it. When crystallised from warm alcohol it forms small fine needles arranged in groups. It is insoluble in water, swelling up in it, however, in the form of a gelatinous mass ; it is insoluble also in cold alcohol and ether, but is soluble in warm alcohol. III. KEPKALINS and MYELINS, &c.— Other phosphorised principles besides protagon and lecithin have been described by Thudichum, which he classifies as kephalins (C^.^H^gNPOig) and myelins (CggHggNPOjj, &c.) They are all soluble in water, kephalin being the more soluble, myelin only slightly so ; while in hot alcohol myelin is readily soluble, but kephalin to a less extent. The myelins are the more stable. They all give the Pettenkofer reaction. In addition to these, other new combinations, such as myeloidin, myelomargarin, neurolic acid, &c., have been de- scribed by KiJHLER; but further proof is required before they can be definitely accepted. IV. DECOMPOSITION PRODUCTS.— Certain of the products of decomposition of lecithin and protagon are the same, and the chief of these are glycerin phosphoric acid, neurin, and fatty acids. (a) Glycerin Phosphoric Acid — C.,H,,P06 or C3H5(OH)2.0.PO(OH)2. It has been found in the brain, medulla of nerves, in muscle, yolk of t'gg, and in bile and pus ; probably, however, it owes its presence to the decomposition of lecithin. It is ohUiined wlion lecithin is decomposed by boiling it with an alkaline solution, and is said to be produced synthetically by adding equivalent quantities of phosphoric anhydride (P2O5) or powdered metaphosphorio acid (HPO;j) to glycerin cont;iined in a vessel sur- NER VE. 3:35) rouucled liy a freezing uiixturc. AVaieris afterwaril.s added, and baric carbonate to ueutralisiition j the haric phosphate is filtered ofl', the filtrate carefully neutralised with dilute sulphuric acid, and the baric sulphate I'emoved. Finally, concentrate in vacuo at a low tempe- i-aturc. Properties. — The free acid forms a syrupy mass that dissolves readily in water; it is dibasic, and is precipitated by salts of baryta and lead. Its combinations with baryta and lime are insoluble in absolute alcohol, but easily soluble in water, the calcium salt (C3Hg(OH).,.().P().02Ca) being more soluble in cold than in hot water; its combination with zinc closely resembles the lactate in crystalline appearance. The phosphorus present in nerve matter is probably in the saturated oxidised form : in this condition it seems to exist not only in glycerin phosphoric acid, but also in lecithin and nuclein. (6) Neurin (Bilineurin, CJioUn), CjHj^NOg, possesses the characters of an alkaloid, and it generally occm-s associated with lecithin. It is identical with cholin, a decomposition product of bile. Xeiirin itself results from the decomposition of protagon and lecithin, and can be obtained from brain, yolk of egg, or bile. Preparation. 1. From Brain. — Wash the brain with water, then break it up, exhaust it with ether, and boil the residue with baryta water to split up the lecithin. After some hours the excess of baryta is removed by sulphuric acid, the filtrate concentrated, and then digested with alcohol. The alcoholic solution is next evaporated to dryness, and the residue treated over a hot air bath with a solution of plumbic oxide to destroy the salts of ammonia. Filter, precipitate the lead with sul[)hiu'etted hydrogen, evaporate to dryness, make an alcoholic extract, and add to this platinic chloride ; on evaporation a doid>le stdt of neurin and platinic chloride is obtained. This last is washed in alcohol, dissolved in water, sulphuretted hydrogen passed through the solution, the whole filtered, and the filtrate slowly evaporated. Chloih3'drate of neurin is thus obt;iined, from which the neurin can be .separated by treating it with silver oxide. 2. From Yolk of Ayy(7.— Exhaust the yolk first with ether and then with boiling alcohol ; distil the mixed extracts, and boil the residue with baryta water. Precipitate excels of baryta with a current of carbonic anhydride, filter, and evaporate to dryness. Dissolve up the z 2 340 TISSUi:S, ORGANS, AND REMAINING SECRETIONS. residue in absolute alcohol, filter, and add platinic chloride, which throws down the neurin. From the yellow crystalline precipitate the neurin is obtained as in the first method. Properties.— Neurin is a syrupy liquid that is alkaline in reaction and soluble in water, alcohol, and ether; it forms combinations with carbonic and sulphuric acids, and double salts with the chlorides of gold and platinum. Neurin is a most unstable body, as when heated it splits into glycol and trimethylamine, C2H,(OH)3N(CH3)3 =^ C.^J^O}i\ (glycol) + N( 0113)3 (trimethylamine). Its hydrochlorate crystallises in colourless needles or plates insoluble in ether, but soluble in alcohol, from which solution platinic chloride throws down a yellow crystalline precipitate. (c) Cerebral Fats, &c. — These bodies appear to result from the decomposition of more complex bodies, such as lecithin and the like. They include stearin and stearic acid, palmitin and palmitic acid, and oleophosphoric acid, &c. Many of them may be regarded as products of tissue metamorphosis. {d) Cholesterin, C^gH^^O. — The brain contains 1*15 to 0-7 per cent. (Flint) ; in the brain of a boy (aet. 15) Benecke found 2-34 per cent., and in that of a woman (tet. 19) 2-12 per cent. According to Bibra it forms about one-third of the cerebral fat, along with the fats constituting over half the total solids of the white substance, and more than one-fifth of the solids of the grey. To extract the cholesterin from a body like the brain divide it into small fragments and digest repeatedly with ether ; decant and evaporate off the ether ; treat the residue with boiling alcoholic solution of caustic potash ; concentrate, adding a little water from time to time, and then shake well with ether. The ethereal solution, when decanted and evaporated, deposits cholesterin ; crystallise the deposit afresh from a mixture of alcohol and ether. Y. CEREBRIN (Oerehric Acid, Cerebrote, Stearoconote), (\-,'i^:i:i^O.^({'.^^U^^fN.J)^, Thudichum). — This is one of the non- phosphorised nitrogenous constituents. Besides occurring largely in the brain, it is also found in the axis cylinder of nerves in the yolk of eggs, and in ])us corpuscles, &c. Preparation. — 1. Gobley prepares it from the ^jolk of rjjh- like residue from which water extracts a colourless crystalline substance. By making a hot alcoholic extract of a number of retinae, filtering hot, washing with warm alcohol, and then ex- tracting with ether, chromophane can also be obtained. The ethereal extract is next to be evaporated and the pale super- natant layer removed with a pipette from the coloured residue (Kuhne). The retinal rods were first described by Krohn, H. MiJLLER, and ScHULTZE as being red-coloured in many animals. Boll next described the retinae of frogs and other animals that had been kept some time in the dark as presenting a purple tint, while the retinae of animals that had been exposed to the direct sunlight were completely colourless. This red or puiple tint of the living retina, which the exposure to light rapidly destroyed, was restored again by allowing the retina to rest in the dark ; indeed, in the living eye this visual purple is being constantly decomposed and as constantly regenerated by the chloroidal epithelium. The red colour appears to reside in the outer limbs of the rods, and to change into a yellow before disappear- ing. Among these red rods Boll also described bright green rods which likewise lost their colour on exposure to the light. KiJHNE's subsequent researches establish the fact that this visual purple, as it has been called, is highly sensitive to light, and that images may be temporarily photographed on the 34G TISSUES, OEGAXS, AND REMAIXING SECRETIONS. retina by its means, and thus produce the accuracy of the visual impressions. Vision therefore appears to be attended with an obvious chemical attraction in the retinal roils, and it is possible that this chemical change may be propagated to the central organs ; but that this change of colour is not essential to correct vision appears from the absence of the visual purple from the eyes of several animals, aud particularly from the most sensi" tive point of the human eye, the fovea centralis. KiJHNE has ohtained this vision purple by acting in the dark on the purple-coloured rods with a two to three per cent, solution of the soda salt of the biliary acids, filtering, and then separating the soda salt by osmose : a myelin, purple-colouied magma was thus separated, whose colour is also removed by ex- posure to the light, first, however, becoming yellow ; or, as Kuhne expresses it, the visual purple has as its products a visual yellow and a visual Avhite. The colour is destroyed by the action of the caustic alkalies, and is taken up by alcohol, ether, chloro- form, iodine, and bromine. The visual purple resists strongly the action of oxidising and reducing agents. KiJHNE only found the visual purple in the outer part of the rods, but absent from the cones, the intensity of the coloration varying in diflferent animals, while in some all coloration is absent. It is said to possess an absorption spectrum. Its carmine red solution in the soda salt of the biliary acids absorbs all the light rays from yellowish green to violet. The red colour presented by the retina imder ophthalmic examination is due in part to this pigment, but also to the blood in the vessels, II. In the pigmentary layer of the retina are to be met with flattened hexagonal nucleated cells filled with pigment. This fascin pigment or melanin (1) occurs as small brownish granules that are insoluble in water, alcohol, ether, and dilute mineral acids. Its origin is supposed to be the ha'uiatin of the blood. It contains 0'25 per cent, of imu, an3 30-0 Ash . OG THE EYE. 347 Coloured oily drops (2) are met with in the retinae of fishes, birds, reptiles, and of some mammals. These drops are yellowish green to a ruliy red colour ; with strong sulphuric acid the colour changes to a dark violet or deep blue. The yellow and red drops contain the same pigment; and the yellow solution of the pigment in alcohol, ether, or chloroform gives two al>sorption bands, one at the line F and the other between F and (j, somewhat resembling lutein. Together with the vision purple there therefore appear to be three pigments in the retina. III. ((/) Aqueous Humour { Lohmever).— Vvx rent. Water 98-68 tu 98-64 Solids , V?,'l „ 1-M Albumin 0-12 „ 0-ia Kxtractives . . . 0--12 „ 0-32 Inorganic salts .... 0-77 „ 0-88 Sodic chloride . . . 0-68 „ 0-77 Potassic „ . . . 0-01 „ 0-06 .'iiillliate . . . 0-02 „ 0-01 Calcic and may UL'sicpliosphato 001 ,, O-Ol The aqueous lunnour contains serum albumin and globulin, which are present in tlie relative proportions of 0-06 and 0-09 per cent. (6) The flnid expressed from the vitreous humour (which is itself mucous connective tissue) has an alkaline reaction, is coagulated by the addition of acids, alkalies, and acetate of lead, but is not coagulated by heat or by the addition of alcohol. The vitreous humour contains only 14 per cent, solids, of which more than half are inorganic salts, together with a little mucin and traces of albumin. It has a density of 1*33. IV. Tears have a simple compt)sition (Lerch); they are clear and slightly alkaline. Por cent . Water '.). Other salts (as alkaline and earthy pliosi)hater.) . Oivj P'or the crystalline lens see p. 29a. V. The Cornea is a lamellated, white fibrous structure which is covered anteriorly by a lamellated pavement epithelium, and posteriorly by an elastic lamina. The white fibrils are ex- 348 TISSUES, ORGAXS, AXB lilJMAINING SECIiETlONS. treraely fine and are arranged in ribbon-like fasciculi that are closely interwoven in layers, between which are plexuses of connective-tissue corpuscles lying in a system of serous canals that form a canalicular system throughout the entire corneal substance. The cornea, unlike ordinary connective tissue, yields chon- drin, or a body analogous to it, instead of gelatin on boiling, the ground substance being chondrogen ; but there is still some difference of opinion as to the actual identity of the product. A solution does not give a precipitate with acetate of lead ; and the precipitate it forms with alum is not soluble in excess; neither does it furnish sugar when boiled with acids. His gives this analysis of the corneal substance: — Per cent. Per cent Water .... 758 Soluble mineral salts . 0-8 Chondrin .... 20-4 Insoluble „ . 0-1 Bodies insoluble in water 2-8 The 'proto'plasm. of the cells yields myosin (Kuhne). The cornea is minced and digested in a saturated solution of sodic chloride for 24 hours in a vessel surrounded by a mixture of ice and salt ; the liquid is filtered and the myosin precipitated by the addition of excess of water. Paraghhulin is removed at the same time, and may be precipitated from the myosin filtrate by passing through it a current of carbonic acid gas. By macerating the cornea in water an alkali albuminate can be extracted. CHAPTER XXI I r. THE SKIN. The skin consists of a superficial cellular layer, the epidevmis (see p. 292), and of a deep thick layer, or cutis, which is formed of connective tissue, and, like it, yielding gelatin on boiling ; it dissolves in great part in acids and alkalies, and combines with tannic acid and salts of iron and inercury. The skin is the seat of a continuous exhalation and absorp- tion of gaseous substances, and to these the name of cutaneous rcsjtinttlou has been given. By the ])erspiration the skin discharges some of the waste products of the body, eliminating THE SKIN. 349 vapour of water, carbonic anhydride, and a little nitrogen, and probably absorbin«>* a little oxygen. If an animal's body, with the exception of its head, be confined in a small chamber filled with air, after some hours the air will have its carbonic anhy- dride slightly increased, its oxygen slightly diminished, and its nitrogen almost unaltered, the oxygen absorbed being somewhat greater than the carbonic anhydride exhaled (Regnault, &c.) The secretion work of the skin is done by the sudoriparous and sebaceous glands ; and the amount de2:)ends greatly on the state of dilatation or contraction of the blood vessels, which is under the governance of the nervous centres, their diameter being directly affected by the activity of the secretory fibres, just as is the case with the submaxillary gland. The Sweat is the secretion of the sudoriparous glands. Normal sweat is a more or less clear and transparent fluid, having a peculiar odour and a density of 1004 ; possessing the character of a blood diffusate, and having dissolved in it a part of the perspiration gases, and a very small proportion of solids. The reaction is alkaline (Luchsinger) ; but as to this authorities differ, some stating it to be acid when freshly collected (probably from containing more of the fatty acids), and becoming alkaline after standing even half an hour (Hoppe Seylek). After prolonged and especially profuse sweating, however, the reaction is neutral and finally alkaline, and at the same time the urea and mineral salts are slightly increased (Funke), the urea of the urine being simultaneously dimi- nished (LEri'.E). Chemical Compositou of Sweat. — The chief components are water and a very small amount of salts and of carbonic acid. IIuiiHin S/rcat (after PiCAKD, SciiOTTlN, &c.) Per cent. Water 98-88 Solids 1-12 Salts 0-57 Sodic chloride 022 to 0-33 Alkaline sulphates, phosphates, and lac- tates, and potassic chloride . . , 018 Fats, fattj- acids, and cholesterin . . O'-ll Epithelium e-17 Urea 008 The mean of the solids is about 1*2 per cent. (1-8 per cent. Funke), 350 TISSUES, OnOAXS, AXD IfEMAIXlXG SECRETIONS. § of which is organic, and about 0-33 per cent, of asli. The water variey from 97 to 99 5 percent. While Funke regarded the excre- tion of urea by the skin to be considerable, Hanke could not find it ; Favke, however, estimated it at O'Oi gram in the 24 hours. Funke also obtained more fixed residue in the sweat of the feet than of the arms, and Schottin found more potassic chloride in the former than in the latter. The ammoniacal salts so often present are probably the result of a decomposition of luea. Comparing iirine and sweat together, the solid.s iu 14 litres are — Sweat. Urine. Gi-ams Grams Chlorides . 34-63 57-01 Sulphates . 016 21-76 Phosphates . traces 5-38 Alkalies expressed as soda . 4-18 2-49 Organic matter . 22-92 139-65 Melanin is the pigment contained in the cells of the rete mucosun/, particularly in the skin of the negi'o. It has already been described as existing in the pigment layer of the retina ; like this body it forms tine amorphous granules that are insoluble in water, alcohol, ether, dilute alkalies, and acids, but slowly soluble in boiling concentrated mineral acids and alkalies. The name melanin, it may be said, is applied to the pigments found in the eye, skin, lymphatic glands, and lung tissue; although it is not exeictly the same iu all these paits, it may be uniformly regarded as a derivative of the blood pigment, with a percentage composition lying within these limits : — c . . 51-7 to 58-3 Fe . . 0-3 n 4-0 „ 5-9 () . I'l'o to ; :]5-4 N . 71 „ 13-8 As ti) the II moil id of water, SEdUJX states that about 1'2 orram of thud is given off by the skin and hing-s in one minute, of which ()"7 gram comes from the skin and ()*5 gram from the lungs — that is, about 18 grains of water i)er minute, 1 1 by the skin and 7 by the lungs. In the 24 hours from 1 to 5 lbs. may be thus discharged, the average loss by the skin varying from 1 to 2 lbs. During vigorous exercise the hand and fore- arm give off, on a summer day with a temperature of 28" in the shade, about 48 grams of sweat in an hour, wliile with \ery moderate exertion in a room at 18° only about 4-3 grams in the same time. Of tlie large amoimt thus excreted by the skin the greater pail [>asses off as insensible perspiration. In THE SKIX. 351 addition to exercise and tempeniture tlie (juantit}' is al'fecled by the dryness of the air, the amount of ihiid drunk, as well as the nature and (juantily of tlie food ; but the activity of the skin depends largely on the state of the kidneys. ]Men(al conditions also exert a considerable influence on the secretion of sweat. The amount of carbonic anhydride is not much above 2 grams in the 24 hours, though by some authorities it is stated to vary between 4 (Aubert) and 10 grams (Scharling) in the 24 hours. It is increased l\v exercise and elevation of temperature. At most the carbonic anhydride thus exhaled rarely rises to the ^Vth of that given off by the lungs (Sciiarlinu) ; but under ordinary circumstances it is probably much less than this, according to some observers the proportion between the carbonic acid exhaled bv the skin and by the lunsfs not beino- more than 1 to 400. INIixed with the sweat we find the secretion of the sebaceous glands, which varies somewhat according to the region from which it is derived. When freshly poured out it forms an oily, half fluid mass, which on cooling appears as a white, greasy body. Under the microscope it presents fatty particles, epi- dermic cells, and cholesterin crystals. It consists of a casein- like albumin, olein, palmitin, soaps, cholesterin, and inorganic salts, particularly earthy phosphates, and alkaline chlorides and phosphates. The Sebaceous S:'cretwii. (riiTIU-.QriN-) (Vl)GEL) AVater 10 Fatty mattero (olein and stearin) 26 Soaps soluble in alcohol and water . . . . .38 Soaps soluble in water and in- soluble in alcohol . . .14 Insoluble organic bodies . .12 Lime and soda . . , traces When the glands are obstructed a thick mass accumulates, consist- ing of altered epithelial scales, cholesterin, fatty matters, and occa- sionally leucin and tyrosin. Pathology. Skhi. — In ichthyosis along with keratin there is much cholesterin, a fluid and a solid fat, and hippuric acid ; and Water , . . . . ;u-7 Solids 68-3 Epithelium and albumin CI-7 Fat (palmitin) 41 Fatty acids (butyric, valeric, caproic) .... 1-2 Ash 1-2 852 TISSUES, OEGANS, AND REMAINING SECRETIONS. silica in the ash. In pellar/^-a there is also a fluid and solid fat, much cholesterin, some leucin and tyrosin, and much silica in the ash. Sweat. — The odour undoubtedly varies in many diseases, and sometimes characteristically so. In jaundice it may be coloured yelloioish from the presence of biliary fragments, and even stain the linen. It may have a blue tint from the presence of some of the indigo derivatives ; hfematin derivatives have also been observed (Robin, Foot), likewise blood in red sweat. Strongly alkaline sweat from the presence of , ammoniacal salts is occasionally met with in uriemia, gout, &c. ; and very acid sweat in acute rheumatism and rickets. Urea has been found increased in the sweat in cholera and uvfemia, and in the sweat of the face in scarlatinal nephritis with anuria ; sugar in diabetes \ albumin in acute rheumatism and forced sweating ; cystin in cystinuria ; lactic acid frequently in puerperal fever, and occasionally in scrofula and rickets ; iiric acid in arthritis, and oxalate of lime in gout. Drugs. — Iodine and potassic iodide, tartaric, succinic, and benzoic acids may appear in the perspiration after their administration ; the iodine ingested is eliminated^ however, less rapidly in the sweat than in the saliva. When mercuric iodide is taken the iodine with a small portion of the mercury appears in the urine and saliva, and the mercury as perchloride in the sweat. After the use of arseniate of iron alkaline arsenites are found in the sweat, and iron in the urine. Quinine, alcohol, sulphur, and assafcetida have been recognised in the sweat after ingestion. By covering the skin of an animal with an impermeable vaiiiish it was stated by R.OHEIG that the temperature was reduced, and a peculiar pyrexia set up, owing to the retention of some of the sweat constituents, or to the consequent dilatation of the cutaneous vessels, or to some other unknown cause that may be classified as the produc- tion of abnormal ti.ssue change. A somewhat similar pyrexia with albuminuria is said to be produced by the injection of the fresh filtered human sweat into the veins of a rabbit. But the effects of the vtii-nisliinir do not appear to be nearly so serious as Koiikkj believed, for tlie author has re- peatedly seen the experiinent jxTforincd wilh coinp;iratively slight results. 353 CHAPTER XXIV. THE LIVER. The liver is the largest gland in the body. Its importance is seen hy the amount of blood present in it, but its close con- nection with the intestine is indicated by its small supply of arterial blood in proportion to the large amount of venous blood containing the absorbed products of intestinal digestion which passes through it. In addition to the important changes it produces on the blood and its corpuscles (possibly being a generator of new blood), the liver is also the scat of the formation of bile and glycogen ; it is further probable that it is one of the great centres of urea formation, although Hoppe Seyler, it should be said, has not been able to find any, or at most mere traces of urea in the liver of a recently killed dog ; and he also failed to find leucin and ty rosin. Chemical Composition. — The fresh hepatic substance is alka- line, but soon after death it becomes acid, owing probably to the development of lactic acid ; it contains 60 to 70 per cent, of water, and 40 to 30 per cent, of solids, consisting, besides certain insoluble tissues, of albumins (of which three are described), fat, and salts of the volatile fatty acids, also of nuclein (in the liver cells), sarkiu, xanthin, hypoxanthin, and uric acid ; but urea, uric acid, and leucin are possibly only pathological constituents. There are, in addition, traces of salts of manganese, copper, and lead. A saccharine and a butyric acid ferment are likewise met with (Pribram). The relative proportiony of the constituents vary somewhiit with age:— Liver of a child (14 daj's old) Liver of an old woman Water . . . .74 14 80-63 Organic bodies . . 2478 18'65 Inorganic constituents . 107 0'7l The constitueDts of ;i human liver are thus given by Bilea : — Water . . . . 76 17 Gelatin .... .337 Insoluble tissues . . 'J 44 Extractives . . . 607 Albumin . . . L'-4U i Fats .... 2-50 A A 354 TISSUES, ORGANS, AND REMAINING SECRETIONS. Of inorganic constituents Oidtmann found 1-10 per cent. Tlic Ash ill 100 Parts. Potash . . 25-17 Phosphoric acid . . 43-37 Soda . . 14-47 Sulphuric „ . 091 Lime . . 3 02 Silicic „ . 0-27 Mdgnesia . 0-19 Chlorine . 2-5 Oxide of iron . 2-75 Lead and copper . traces The proportion of fat depends more or less on tlie food, as its pro- portion is increased with a diet ricli ia fat. In the normal condition the fat present seems to be proportional to the fat in the i-est of the organism. The quantity of glycogen is very variable, depending greatly on the character of the food ; normally it averages 1-5 to 2-5 per cent. In dogs fed exclusively on meat the liver may contain about 7 per cent., -n'ith a purely vegetable diet as much as 17'2 per cent , and with a mixed diet about 14-5 per cent., the glycogen disappearing when the animal is starved. According to Seegen and Kratschmer the sugar in the liver increases after death to an extent not to be ac- counted for by the transformation of the glycogen present. In the case of a young fox they found in the liver two minutes after death glycogen 0-7 per cent, and sugar 0'79 per cent. ; an hour later, sugar 1-83 per cent.; 24 hours later, sugar 1-98 per cent. More sugar was therefore formed than the glycogen in the liver could possibly account for. But Boehm and Hoffmann object to this conclusion, on the ground that something other than sugar was reckoned as such. The hepatic cells are devoid of cell walls and possess one or two nuclei. As constituents of the dead cells we find an albumin coagulating at 45° ; nucleo-albumin (Pl6sz), soluble in water and in solutions of sodic chloride and sulphate, and coagulating at 70" ; an albumin resembling myosin, coagulating at 75° ; free nuclein and a body resembling coagulated albumin ; glycogen, grape sugar, and a diastatic ferment ; fats, particularly olein, about 2*5 per cent. ; pigments, potassic and sodic phos- phates, and water. To prejjare fjlycogen and liver ferment, and to demonstrate 8Uf/ar in tke liver, see pp. 50, 162, 5i. For hlle, &c., also see p. lOG. THE LlVEli. S65 Pathology. BlUHA FoLWARCZNY PHEKIfH.S OlDTMANN Fatty liver in tubercle Tyiihoid liver In diuljctcs In om- liolism of the licpatic artery Fatty liver Cirrhotii liver Syphilitic 1 liver in a j new-born child Water . 710 7.")- 1 7.5-3 80-7 730 80-2 82-5 Soluble albuminoids 13 2-6 6-7 2-1 36 3-5 1 Uel.it in . p]xtracti\X's 44 2 6 4-0 •t.5 11 2 2 11 a-6 !- 19 ; 11-5 16-5 Fats 17-4 ;^:i ID 2-i 17-2 22 ) Insoluble tissues „ salts •61 1 10-2 11-7 «-9 <»5 4 3« ; 91 Soluble — — ()!> 0-4 /'«/«.- -While the noinml liver contains only about 2 to 3'5 per cent, of fats (that of the cat normally about 7 per cent.), and 19 "5 to 20 7 per cent, other solids, in acute atrophy of the liver the fats may rise to 76 per cent., and the other solids sink to 155 per cent., and ill fatty liver the fat may be as high as 195 per cent,, and the re- maining solids IS'l per cent. This increase may occur in diseases of the respiratory organs, as phthisis, etc., and as a result of chronic alcoholism, degeneration, etc. The (jl()GO(j(in is greatly diminished in fevers, and in arsenical and phosphorus poisoning; it may be absent from fatty liver, and it is increased in diabetes. rhftnents apparently identical with hsematin accumulate in the liver in malarial affections, and in yellow atrophy we may find ciystals of bilirubin. Urea is increased, together occasionally with Icuci/i, ti/rosiu, cyntin, etc., in acute yellow atrophy and carcinoma of the liver, in many zymotic di.seascs, acute rheumatism, pyaemia, malarious ca- chexias, syphilis, tuberculosis, some diseases of the spinal cord and heart, chronic pleuri.sy, and in many cases of anremia and jaundice. Leucin, it may be remarked, increases in the liver after death, and t'Sjjecitilly during putrefaction. Concretions are met with now and again in the substance of the liver. They generally consist of organic matter 35 to 40 per cent., with calcic phosphate and carbonate about 32 per cent. lioG TISSUES, OROAXS, AXD REMAINING SECRETIONS. CHAPTER XXV. THE PANCREAS. The fresh human pancreas is alkaline in reaction and con- tains 17*4 to 25'5 per cent, solids and 74*5 to 82-6 per cent. water. Of the solids there are serum albumin, an alkali albu- minate like casein, fats and volatile fatty acids, extractives, and salts. Among the extractives present are guanin (0'12 per cent.), xanthin (0-0016 per cent.), leucin (1*7 per cent.), inosit, butalanin, lactic acid, and traces of uric acid and tyrosin. No mucin is contained in it. Yor jjancrecitic jidce see p. 188. Pathology. — The pancreas may be the seat of tumours (cancer, adenoma, &c.) or of infiltrations and degenerations. Very often, in such cases, the properties of its secretion are altered, and accordingly some of the intestinal contents may escape digestion, and this has been noticed chiefly in the case of the fats. CHx\PTER XXVI. SPLEEN. This organ is provided with an elastic capsule containing muscle-fibre cells, which is prolonged inwards on the blood vessels at the hilus of the organ. Enclosed by this capsule is the splenic pulp, that is supported by a coarse trabecular frame- work as well as by a delicate meshwork forming a honeycomb of membranes in connection with the vessels (Klein). The red pulp itself is made up of cells of different kinds and of blood corpuscles, particularly the pale ones, in different stages of change. Here and there are to be seen little spots of white pulp, the Malpighian corpuscles, which consist of small clumps of lymphoid infiltration in the sheath of the small arteries. Functions. — It is possilde that besides destroying old blood corpuscles it assists in forming new ones, the pale corpuscles especially ; and it is said to prepare the proteolytic pancreatic ferment (Schiff), though this is denied (Mosler). It acts SPLEEN. 357 also as a regulator of the Wood contents of the liver and stomach. Chemical Composition. — In the fresh state the spleen is alka- line, but it becomes acid some time after death. The compo- sition of the pulp may be thus stated {after Oidtmann, &c.) : — Hiimnn Sjdrrn. Per cent. Water 70 to 77 Organic matter 2S ., 30 Inorganic constituents .... Go „ 09 „ „ in the 100 parts — Soda 35 „ 45 Totash „ 17 Lime 7 Phosphoric aci'l . . . . 18 „ 30 Oxide of iron . . . . . 7 „ 1 6 Chlorine OS,, 1-3 Sulphuric acid . . . . . r5 „ 2-5 Silica 0-2 „ 07 Manganese, cojjper, and lead . . traces There is some difference of opinion as to the occurrence of free iron in the spleen, but that iron is present in large excess, associated in some way with an alkali albumin, there seems to be no doubt ; it appears also to increase with age, and of combined iron Nasse has found 5 per cent in the dried pulp of the spleen of old horses. The organic constituents include albumins, much inosit, choles- terin, cerebrin, xanthin, hypoxanthin, traces of leucin, uric, succinic, and lactic acids, fats, and iron-holding pigments. Tyrosin is a j^ost- mortem constituent, and the volatile fatty acids, such as formic, acetic, and butyric, are decomposition products, probably of the haemoglobin products of the red pulp. In its composition the splenic pulp differs from blond in the large amount of its soda and phosphates, and in the smaller proportion of its potash and chlorides, and it is characterised by its richness in extractives and 2:)igments. Uiic acid is always pi'csent, and seems to be connected in some way with splenic activity, particularly under abnormal conditions, as seen in ague, &c., when an increase in the uric acid in the urine accompanies an enlargement of the spleen. Pathology. — In diabetes no glycogen is present, but a little sugar is to be met with ; xanthin has been found in hypertrophy. In leukaemia the spleen is rich in sarkin, uric acid, and bodies allied to gelatin. Robin, Charcot, and Neumann have found peculiar crystals in the spleen in leukaemia. These crystals have been re- 358 TISSUES, ORGANS, AXD EEMAIXIXG SECRETIONS. garded as of the natiive of tyrosin, but this has been denied. ScHREiNER describes them as consisting of a phosphate of a base having the composition C^H^N ; and he states that he has fouml a similar body in the human semen to the extent of 5'23 per cent. These crystals are met with also in the sputum of bronchitis, and in the blood Fig. 26.— Charcot-Nkumaxx and marrow in leuksemia. They are of a double pyramidal shape, and are insoluble in alcohol, ether, chloroform, and cold water, but soluble in alkalies and dilute minei'al acids, acetic acid, itc. Amyloid degenei'ation is frequent in the organ. CHAPTER XXVIL SrPRATiENAL CAPSULES, THYMUS, THYROID, LYMPHATIC GLANDS, AND KIDNEYS. I. SUPRARENAL CAPSULE.— The medulla of this body has been considered nervous in its nature on account of its richness in nerve elements, while the cortex is glandular, somewhat of the character of lymphoid tissue. In the medulla together with albuminous bodies there is found a material that is soluble in water, and, particularly when exposed to the direct sunlight, furnishes a beautiful red pigment. The colourless extract is reddened by the action of watery solutions of chlorine, bromine, or iodine, and is stained of a dark blue to a green by perchloride of iron. Alcohol extracts this chromogen, and the solution gives a reddish precipitate with acetate of lead, which turns green on exposure to the air. A very dilute hydro- chloric acid extract of the gland is coloured red on the addi- tion of excess of ammonia, violet flocculi being precipitated. Leucin, inosit, hypoxanthin, hippuric acid, benzoic acid, myelin, fats, and possibly taurin and taurocholic acid are all said to be present. Among the inorrjanic constituents we find potassic chloride in large amount, also phosphates of potassium, sodium, calcium, and magnesium. This excess of potash and phosphoric acid speaks in favoiir of the nervous nature of i\m organ. THYMUS. 359 The juice of the gland is neutral or weakly acid. The proportions are thus given by OiDTMANN in the suprarenal of the dog: — Water . . . 8003 Organic matter. . 19-88 Inorganic „ . . 0-09 In Addison's disease it has been found degenerated. II. THYMUS. — This gland atrophies towards puberty, after having undergone fatty degeneration. It consists in great part of a sort of lymphoid tissue supported by fibrillated connective tissue. Chemical Composition. — Tn a Calf of Z Months (Simon). Water . . 77 Albuminoid material 4 Salts 2 Fats . traces Jn a Puppy (Oidtmann). Water . . 80-7 Organic matter . . 19-2 Inorganic „ . 0-2 The chief solids are the following : soluble albumin, gelatin, fat, and elasticin ; leucin, xanthin, hypoxanthin, succinic, lactic, and traces of other fatty acids ; salts rich in phosphoric acid, potash, and soda ; but, except in the very early peiiod of the gland, potassium replaces sodium, being about three times more abundant ; traces of salts of lime, magnesia, and ammonia, and of sulphuric acid and chlorine are likewise met with. In the thymus of a calf, three weeks old, there was found only 1*3 per cent, fat, while in that of a young heifer of 18 months as much as 16 8 per cent, was present. III. THYROID. — This organ is made up of connective tissue, scattered through which are a great number of different- sized cavities, more or less globular in shape ; these are filled with a transparent fluid that is analogous to mucus ; there is present in this fluid a little albumin and traces of sodic chloride and oxalate of lime, &c. The juice of the gland also contains leucin, xanthin, hypoxanthin, volatile fatty acids, succinic and 3G0 TISSUJES, ORGAXS, AND REMAINING SECRETIONS. lactic acids, and cholesterin. In the small cysts little or no albumin is present, but in the larger cysts as mucb as 7 to 8 per cent, may be found. This fluid material of the cysts is very liable to undergo colloid degeneration, and in goitre it is produced in great excess, cholesterin crystals also being fre- quently abundant and occasionally crystals of bilirubin. An alcoholic solution of chinolin blue stains this colloidal material of an intense blue. OiDTMANX gives the subjoined as the general percentage compo- sition of the gland ; — In a cbild In an aged female Water 77-2 82-2 Organic matter . . . 22-3 17-6 Mineral salts . . .0-5 0-9 IV. LYMPHATIC GLANDS contain about one-third their weight of solids, among which have been found nuclein, leci- thin, albumin, cholesterin, leucin (but no tyrosin), xanthin, &c. V. KIDNEYS. — -The capsule is white fibrous tissue, and a certain amount of connective tissue is also found supporting the tubes. The renal tissue has a mean density of 1050 ; its reaction is alkaline, but it speedily becomes acid when exposed to the air. Child's kidney Kidney of an old (aet. 14 days) womaa Water . . . 77-82 81-09 Organic substances . 21-47 17-92 Inorganic „ . 0-71 010 (Oidtmann). A cold ivatery extract of the kidneys contains albumin, xanthin, hypoxanthin, kreatin, taurin, leucin, inosit, cystin, glycogen, and occasionally also urea, uric acid, and urates. If a solution of subacetate of lead is added to it, the resulting precipitate suspended in water, decomposed there with sul- phuretted hydrogen, and alcohol added to the filtrate, which is then gently warmed, a crystalline precipitate of inosit, cystin, taurin, xanthin, and sarkin is obtained. By warming this deposit with carbonate of soda solution we obtain on filtration a solution of cyslin and inosit, from which the cystin can be pre- cipitated by the addition of acid. KIDNEYS. 361 Ki(lne3-s thoroughly washed out with sodic chloride solution (^' per cent.), to get rid of the blood, gave in the 100 parts the follow- ing organic constituents (Cottwalt) : — Serum albumin a mean of 1-25 Globulin substances „ 3-818 Albumin extracted by common salt solution (10 per cent.) » 523 Albumin soluble in and extracted b}- sodic carbonate „ 1'52 Gelatin „ 1016 Mucin traces BuNGE and SuHMiEDEBERG are of opinion that hippuric acid has its seat of formation in the kidneys, the glycocin and benzoic acid residues being combined under their agency, the presence of blood corpuscles, however, appearing to be essential. Pathology. — In consequence of inflammations of different kinds, and as tlie result of the altered blood in phosphorus poisoning, ex- cessive alcoholic ingestion, septicaemia, and severe eruptive fevers, the renal epithelium may become charged with granulations of the nature of casein ; while a long continuance of one of the above conditions may fiu-ther lead to the appearance of fatty gi'anules, which possibly i-eplace and are derived from the albumin granules, and thus lead to a subsequentya^^?/ degeneratio7i. In some cases purulent abscesses may appear among the tubes, or excess of leucocytes. In gouty conditions deposits of urate of soda frequently present themselves, and different morbid growths at times attack the renal substance. In various abnormal conditions bodies may be present that arfe only rarely to be met with normally, and then in but slight amount : thus leucin and tyrosin have been found in cholera ; uric acid in tuberculosis, delirium tremens, and Bright's disease ; and grape sugar in diabetes mellitus. A calcareous degeneration of the cortex of the kidneys has l^een noted in acute mercurial poisoning (Salkowski), and it would appear that this calcification of the renal tubules accompanies a removal of lime salts from the bones. 362 TISSUJES, OUGAXS, AXB REMAINING SECRETIONS. CHAPTER XXVIIl. THE LUNGS. Owing to the large amount of elastic tissue, smooth muscle, connective tissue, cartilage, and epithelium present in the lung, the chemical constituents of these tissues will figure largely in the chemical composition of the lung, and accordingly we have much elasticin, mucin, myosin, chondrin, and gelatin ; there is also casein, lecithin, leucin, inosit, and in the lungs of oxen taurin : further we have uric acid ; inorganic salts, chiefly chlorides, sulphates, and phosphates of sodium, potassium, calcium, magnesium, and iron ; and silica. Lung substance contains more coagulable proteids than muscle, and less albuminoid extractives. The embryonic lung is rich in glycogen ; in the embryo of the sheep it has been found as high as 50 per cent, of the dry solids ; but it is wanting in the lungs of adults. In the fresh state the reaction of the lung tissue is alkaline. Of ash in the dry solids there is found 2 to 7 per cent., chiefly alkaline phosphates, sodium chloride, and iron. The richness of the ash in phosphoric acid is due probably to the lecithin present. Lung of Infant (OlDTMANN). Water .... 79-f5 per cent. Organic matter . . .19-8 „ Mineral „ . . . 06 Verdeil has described a special acid, pneumonic, which he has isolated (taurin?). A black pigment consisting chiefly of carbon (85 per cent.), with a little nitrogen, hydrogen, and ash, is present in the lung suhstance. Pathology. — The lung may contain tubercle, which will present different appciirances according to its condition. Caseous Tubercle (SisrON). Per cent. Water 826 Tn.soluble organic matter .... 120 Substances soluble in alcohol. . . , 2\ Fatty bodies, cliolesterin, cerebrin, &o. . . r86 Watery extract 084 Mineral salts 0-49 THE LUNGS. 363 Calcareous Concretions are often present in these tubercular deposits ; they vary in composition. Insoluble salts . . .70-1 per cent. Soluble ..... 295 „ (Roudet). The soluble salts consist chiefly of sodium chloride mixed with phosphate and sulphate of soda ; the insoluble salts, chiefly of phos- phate of lime with a little carbonate, silica, and oxide of iron. They sometimes also contain cholesterin and a little proteid substance. Concretions are also occasionally found in the lung tissue, as well as in the nose, tonsils, and tracheae, &c. ; they consist of mucin, fat, I)hosphate and carbonate of lime, and magnesia. They may contain 86 9 per cent, of inorganic salts, chiefly phosphate and carbonate of lime with traces of iron (Biermer) ; or consist of 70'1 per cent, of soluble salts (sodic chloride, phosphate, and sulphate) and 29-5 per cent, of insoluble salts (calcic phosphate and carbonate, silica, &lc.), as given above by Boudet. A Lrtng Calcvlus (Sgarzy). Fatty matters and cholesterin . . 1.5'6 Calcic phosphate and carbonate . . 3'9 Mucin and albumin .... 7*2 Magnesic carbonate .... 0'9 Silica 0-8 Water 1-2 In pneumonia the lung becomes hepatised, which is owing to the solidification of the blood derivatives poured out into the air cells. In this condition glycogen has been found in considerable quantity. Melanic as well as other tumours occasionally show themselves in the lung tissue ; and well-marked pigmentation of the lung may be produced by an accumulation of oxide of iron particles, as in sider- osis ; or of fine carbon particles, as in anthracosis. In ansemia leucin and tyrosin are often present ; in Bright's disease, urea, uiic and oxalic acids, inosit, and occasionally ammoniacal salts ; in diabetes, glycogen and glucose ; and occasionally the same in purulent pneumonia ; in tubercle, cholesterin ; and in calcareous de- generation, much lime salts. Sputa consist of the secretions of the mucous Hning of the respiratory tract, occasionally mixed with saliva or nasal mucns. Normally there is very little secreted, while in different diseased conditions the quantity is generally considerable, but it is very changeable. As examples the sputa of a few pulmonary diseases will be given here. 304 TISSUES, ORGANS, AND REMAINING SECRETIONS. Diseases putii in strains in the 24 iiours 135 74 124 Water 97 0-98? 90-09-93-I 94-5 Solids Organic coMSCitu- Mucin cnts Albu- min Fat ^^t'-'-i"- Ash tives Broncli'tis Pneumonia . Phthisis 1 •7-2-3 6-3-9-01 5-5 M7-1-7 1 0-(.9-l"2 5-5-8-35 1 -1-1 -28 4*7 ! 1-8-2-4 — i - •! 0-48 3-09 0-02-0:!2 2-8-3-fi5 0-29-0-49 U-3G-0-39 l-G-2-01 0-53-0-(i*f 0-76-0-8 In pueumonia the quantity may vary from 26 to 122 grams in the 24 hours; of the rusty sputa, from 30 to 300 grams; and in the stage of resolution, from 250 to 300 grams. In phthisis it may range between 80 and 150 grams, but the daily quantity is variable, much more so than is the case in bronchitis. The sputa in different pulmonary affections vary greatly in colour, odour, viscidity, thickness, &c. In consequence of chronic inflamma- tion of the bronchi, especially when the air l:>reathed is rich in particles of carbon, as with miners, &c., the expectoration may be quite hlack ; red, from the presence of blood or blood pigment ; or green, from biliaiy pigment. A putrid odour is given off by the sputum in cases of gangi-ene of the lung and bronchiectasis. As to salts, a large propoition of alkaline chlorides and phosphates, with a small proportion of sulphates, is usually present. In an acute catarrh the mucus had this composition : — Water Solids Organic Mineral 97-9 2-1 1-36 0-63 But if the irritation is long-continued or excessive pus also may make its appearance. In old-standing bronchitis there are compara- tively few cell elements in the expectoration, and, as we have seen in the table, little or no albumin or fat ; but in acute bronchitis, acute congestion, and occasionally in hydro-pneumothorax, the albumin is much increased. In pneumonic sputa the amount of fat is small, but that of the extractives abundant, and the same holds good in phtliisis. In tubercular phtliisis the sputiim may contnin tubei'ole corpuscles and debris of different kinds ; blood may also appear in such cases as well as in pneumonia, and it may be so abundant as to be readily recognised, or it may be so slight as to be masked. In case of doubt examine for blood by the haiinin and spectroscopic tests. Pnaumnnic sputum in the early stage of the disease is brown or yellowish red, viscid, and somewhat translucent, consisting of a mixture of mucus, reddish serum with blood corpuscles, epithelial cells, and threads of fibiin, together with coagulable albumin. When THE LUNGS. 365 the lung is hepatised the colour of tlie sputum is less marked, but it becomes more viscid, and it may be greyish or purulent, and contain an excess of sodic chloride. The amount of this last salt is very considerable. In a case of pneumonia of the sixth day its proportion to the litre of sputum was equal to 4*5 grams, only 0'5 gram appearing in the urine of the 24 hours in the same time, while on the loth day of the same case the proportion was equal to 820 grams per litre, and in the day's urine to 2"52 grams. According to Nasse, 1 litre of laryngo-bronchitic mucus contains 5 "8 grams of alkaline chlorides. In grey hepatisntion the sputum becomes brown, less viscid, and presents greyish streaks ; it is rich in albumin, and contains also mucus and pus corpuscles, fatty granules, and epithelial cells. It should be remembered that the colouring matters of prunes, rhubarb, ifec, may communicate a reddish tint to the sputum. CHAPTER XXIX. RESPIRATION. Respiration is esseDtially a chemical phenomenon in which oxygen is absorbed, and carbonic acid and water exhaled at the lungs, the two latter compounds resulting from oxidations that have occurred in the tissues. Changes eflfected upon the Air by Respiration. — The air in its passage through the lungs undergoes several changes. 1. The inspired air loses 4-7 per cent, oxygen, and the expired air gains 4*3 per cent, carbonic acid gas (Vierordt). 2. The expired air is satm-ated with aqueous vapour. 3. The temperature of the inspired air, if somewhat lower than that of the body, is raised to 33° to 36°, the exact tem- perature, however, depending on that of the air, and on the depth and rate of the respirations ; but if the temperature of the inspired air is very low, then it will not be so high — i.e. temp, of inspired air 6*3°, temp, of expired air 29*8° (Valentin). 4. The volume of the expired air is slightly less (from J^th to yi^th) than that of the inspired air, while the volume of carbonic acid gas added to the air is nearly equivalent to 3G0 TL%SU£S, OliGAX.S, AXl) IIEMAIXING SECRETIONS. that of the oxygen absorbed, the carbonic acid containing its own volume of oxygen ; yet a little of the oxygen inspired does not thus reappear in the carbonic acid of the expired air. 5. The expired air is also said to contain traces of ammonia^ hydrogen, carburetted hydrogen, and other hydrocarbons ; per- haps also a slight trace of nitrogen in excess of that inspired, and very slight traces of organic bodies badly known. Some of these bodies probably arise in the intestinal organic decom- positions (Pettexkofer) As to ammonia, young individuals produce more than old, and small proportionately more than large animals. For every 100 lbs. body weight an adult man expires in the twenty-four hours about 3-9 grains, and a young boy about 6'2 grains ammonia (Grouven). According to LosSEX, however, the average in the twenty-four hoiu's for an adult is 0-014 gram (0-22 grain). The amount (A free nitrogen in the system depends greatly on the atmospheric pressure : if this is lowered nitrogen leaves the body; so also if the temperature is raised. In a state of hunger some nitrogen appears to be absorbed, while with well- nourished beasts a little seems to be exhaled from the organism. Pettexkofer and Yoit, however, deny that free nitrogen is eliminated from the body to the extent asserted by Seegen and NOWAK. The oxygen of the inspired air traverses by diffusion the fine membrane separating it from the blood, and it is then taken up in great part by the haemoglobin of the corpuscles, with which it forms an unstable combination ; a small proportion is also dissolved in the liquor sanguinis. Of the carbonic acid exhaled for every five parts only one part comes from the corpuscles, and the remaining four from the plasma. (I) The portion in the corpuscles is probably com- bined with the haemoglobin ; (2) that in the plasma is partly in a state of simple solution, while the rest (3) is feebly com- bined with the sodic carbonate and i)hosphate of the serum (ZuNTz). One chemical equivalent of common phosphate of soda enters into a loose combination with the same quantity of carbonic acid as two equivalents of carbonate of soda (Fernet). This loosely combined carbonic acid is readily evolved by re- duction of pressure or tlif^ passagf of anntlier gas, especially in RESrili. [ TION. 'M7 presence of albuminous bodies (Sertoli) or in that of the coloured corpuscles (Preyek). The oxyhtcmoglobin which is formed in abundance early in the respiratory act would thus appear to perform the part of an acid in liberating the combined carbonic acid. Indeed, according to Holmgren, the presence of oxygen in the lungs greatly increases the tension of the car- bonic acid in the blood. Other circumstances also assist ; thus the rapidity of the blood current, and the great extent and moist condition of the respiratory surface, no doubt fticilitate the diffusion and exhala- tion of the carbonic anhydride. Possibly also the diminished pressure in the air cells may assist in the elimination ; and that some reduction of pressure in the interior of the lungs is possible we know to be the case. After Bonders this is a normal occur- rence, in some animals to the extent of —3 mm. and in man — 1 mm. mercury, and in a forced inspiration to as much as — 57 mm. But as to the exact rationale of the expulsion of the carbonic acid gas, our present knowledge is insufficient to enable us to say ; and it is accordingly possible that other agencies are at work than we are yet acquainted with ; indeed, none of the hypotheses that have been given hitherto can be regarded as perfectly satisfactory. While the solubility oiiYie nitrogen in the serum is regarded as the same as that of the gas in an aqueous solution of the salts of that fluid (Fernet, &c.), some consider the coefficient of solubility to be higher, the corpuscles possibly uniting feebly with a small quantit v of the nitrogen (Setschenow). As to the absorption of nitrogen in respiration nothing decisive can yet be said, but if it does occur at all it must only be in very small amovmt. For every 100 vols, air inspired only 99"25 are expired, if calculated as dry air at the same temperature and pressure. This, as we have seen, is due to part of the oxygen absorbed not being replaced by carbonic acid gas. As a general rule, for every 100 parts of oxygen which disappear in the lungs, only 86 reappear in the carbonic acid gas, and nine or ten or more in the water exhaled. An adult man absorbs in an hour 28 to 36 grams oxygen, and he exhales in the same time 31 to 41 grams carbonic anhydride, corresponding to 22'j to 30 grams of oxygen S68 TISSUES, ORGAXS, Ayi) EI^MAiyiXG SJECEETIOyS. and 8'5 to T 1*2 grams of carbon. The 5'5 to 6 grams of oxygen that have thus been retained in the organism are used up there in the different oxidations of the economy. One of these pro- ducts is water, of which more is excreted than is absorbed. The extractives, including urea, &c., also carry away with them part of this retained oxygen. Quantity of Air, Carbonic Anhydride, and Water Inspired and Expired. — 1. After the most complete expiration 1,200 to 1,600 c.c. (73 to 97 cubic inches) of residual air remain in the lungs, or according to Gkehant 1,700 c.c. (104 cubic inches). 2. After an ordinary expiration there remain 2,500 to 3,400 c.c— that is, from 1,300 to 1,700 c.c. (79 to 104 cubic inches) — of swpjjleinental air. 3. The air taken in and expelled in each ordinary respira- tion — the so-called tidal air — forms -i-th to -^'oth of the vital capacity, or about 500 c.c. (30 cubic inches); it varies with age and size, &c., and may only amount to 330 c.c. (20 cubic inches). 4. The term complemental is applied to the quantity that can be inhaled after the deepest possible inspiratory effort beyond that introduced by an ordinary inspiration ; it averages 100 cubic inches. 5. The vital capacity, as it was termed by Hutchinson, is the amount of air expelled by a forced expiration after a forced inspiration. It varies from 200 to 300 cabic inches, being in- fluenced chiefly by the height and weight, 8 additional cubic inches accompanying every inch of stature from 5 to 6 feet ; corpulence and old age, on the other hand, causing a diminu- tion in its amount. The number of inspirations in a minute average from 16 to 19. The total air respired in the twenty- four hours equals about 1 1 cubic metres (330-5 cubic feet), or 458 litres per hour (13*7 cubic feet), about 700 grams (355 litres, or 625 pints) of oxy- gen being consumed in the twenty-four hours. An adult inspires about 7 litres (427 cubic inches, or 12-3 pints) per minute, and expires in the same time about 320 c.c. (0-5G pint) carbonic anhydride, and in the twenty-four hours about 800 grams carbonic anhydride (406 litres, or 714^ pints). RESPIRATIOX. V,(V.) Dumas gives the carbon exhaled by the skin and lungs in the twenty-four hours as 8^ oz., and P]. Smith as 7* 14 to 11-7 oz. The water exhaled by the lungs in the twenty-four hours averages between 350 and 500 grams (| to f pint) ; but some authors state the amount as averaging somewhat less than this, or only 10 oz. The former estimate would give a mean of 0*05 gram in each litre of air expired, a quantity varying, how- ever, with the state of the organism as to bodily heat, re- spiratory depth and rapidity, and of the atmosphere as to temperatiure, pressure, and hygrometric condition. The accompanying table indicates the changes effected in the air by the respiratory exchanges, and also the proportion of the gases in the blood : — In 100 volumes Atmospheric air (Dumas) Oxygen . Nit rogen Carbonic an- hydride Per cent. 20-81 79 U) 0037 to 0062 ICxpiied air (Biiux.NEi; and Valentin) (Speck) Per cent. 1603:} 79-.0.57 4-380 Per cent. 16-43 to 16-84 79-48 „ 79-55 4-09 3-61 Blood gases (Pfluuer) Per cent. 38-08 3-09 58-83 The aqueous vapour in the expired air is variable, depending on the temperature ; it averages 1"4 per cent., but the air con- tains only about three-fourths as much as it can hold when saturated, and in winter the proportion present is greater than in summer, although it is capable in summer, on account of the higher temperature, of holding nearly three times the usual quantity present. A trace of ammonia is often present in the air, and occa- sionally traces of other gases in the air of large towns. Circumstances aflFecting the Respiratory Exchanges, particularly with reference to the Carbonic Anhydride. 1. State of Rest or Activity. — The greater the labour effected in a given time the greater is the consumption of oxygen, and the greater the elimination of carbonic anhydride ; but \\\e period of increased exhalation of carbonic anhydride dependent on muscular work is generally followed by a period of diminished exhalation (Raxke). B B / 370 TISSUES, ORGANS, AND REMAINING SECRETIONS. As the result of observations made on dogs in a state of repose and in a state of tetanus, the amount of carbonic acid gaa expired was noticed to be increased proportionally to the degree of muscular work, during the period of rest an accumulation of oxygen also occurring in the system (Sczelkow and Ludwig). Muscle work, therefore, occasions a proportionally rich excretion of carbonic anhydride and absorption of oxygen in a given time, the venous blood coming from the active muscle being richer in carbonic acid and poorer in oxygen than the blood flowing away from a muscle at rest. The frequency and depth of the respirations accordingly bear a relation to the amount of muscle woi'k, this increased frequency lasting for some time after the work has ceased. Muscle work also greatly increases the water exhaled, sometimes more than doubling it. 2. Food. — The oxygen absorbed is employed for the oxidation of albumin, fat, and carbohydrates. While most of their carbon is burnt up, appearing as carbonic acid, part is otherwise excreted in urea and uric acid, &c. The sulphur also of the albumin is oxidised to the state of sulphuric acid, and the hydrogen to the state of water. Fats, we know, are very rich in hydrogen, and accordingly much oxygen is used up in their oxidation ; carbohydrates, on the other hand, are more easily oxidisable, as they contain in themselves suffi- cient oxygen to combine with the hydrogen present to form water. Some cai'bonic acid is undoubtedly formed in the body as the result of fermentation and other similar pi'ocesses. Part of this, by diffusion from the intestine, enters the blood and is discharged at the lungs. The quantity of air respired and of carbonic anhydride exhaled has two maximum and two minimum periods in the 24 hours, cor- responding to the two chief meals of the day, breakfast and dinner. Less of the gas is expired during fasting than after food, and it is largely increased by an albuminous diet. A diminution in the exha- lation is said to occur after the ingestion of alcohol, tea, &c. The building up of the carbonic acid, it must be remembered, is not a respiratory act, or at least only so to a slight extent ; it really depends upon the living cells of the orgnnisra, which i-egulate the consumption of oxygen and the breaking down of tissue. The carbonic acid thus generated is conveyed to the lungs to be discharged. As to this consumption of oxygen in the economy, Pfluger is of opinion that each living cell regulates its own consumption, and is independent of the pressure, even when pure oxygen is lespired the intensity of internal comlnistion remaining the same as with air. HESPIRATICN. 371 Itoiijiriitorij Exrliangcs in Healthy Mot under 1)1 [fi rent Condilintia (Pettenkofer and Voit). Oxjgeu absorbed, in grams t'arloiiic aciil ex- pivefl, ill grams Water expired 1 Total ' Total Total Day Night in iA Day Night 1 in 24 Day Night in 24 ' hours hours liours Without foorl J rest 420 323 743 379 316 695 463 351 814 1 work . i)22 150 1,072 930 257 1,187 1,425 352 |1,777 Mixed diet ( rest 469 460 911) 539 404 943 534 475 11,009 ^ work . 795 211 1,006 828 306 1,134 1,035 377 11,412 Albuminous j rest 632 218 850 580 423 1,003 696 414 il,110 diet ' work . 566 310 876 596 442 1,038 644 563 1,207 Non-nitrogeno us food — 1 rest . • 523 285 808 508 331 839 566 359 925 8. Ivjlucnce of Hunger. — The expired air is only half naturated with aqueous vapour (E. Smith). While the absolute quantities of oxygen absorbed and carbonic acid exhaled diminish, their proportion to the body weight increases somewhat. Starving beasts are said to absorb nitrogen from the air (Regnault and Reiset). 4. Day and Night, Light and Darkness, and Hleep or Wakeful- ness. — The elimination of carbonic acid is increased in the light and diminished in the dark. Animals^^ it is known, fiitten more rapidly if kept in darkness. During the day the elimination of carbonic acid is greater than in the night, but during the night less oxygen is exhaled than is absorbed. The colour of the light is said to produce a difference, but the results of oVjservers differ, some affirming that the most active evolution of carbonic anhydride occurs with a yellow light (Selmi) ; others, with violet (Bechand) ; and others again, with yellow and green (Pott). Duiing the period of hybernation that occurs in some animals only a small amount of carbonic anhydride is exhaled. It is said also that during the same time these animals absorb and retain a certain amount of nitrogen, but a far greater amount of oxygen. During sleep the exhalation of carbonic anhydride is diminished and a slight amount of oxygen is absorbed and I'etained beyond what occurs during a period of wakefulness. Thus, comparing the respective exhalation of carbonic anhydride and absorption of oxygen dui-ing rest and labour for the day and night, we have — Rest Labour For 100 CO, exhaled For 100 oxygen absorbed Dav N^ght . 58 48 Day 33 Night 67 69 31 31 69 (1 'ETTENKOFEE .and VoiT) 372 TISSUHS, ORGANS, AND REMAINING SECRETIONS. 5. Sex, Age, cbc. — The respiration is more active in the male than the female ; and between 20 and 30 is the period of greatest activity, bub proportionally to the weight the activity is greatest in youth (Pott), relatively more oxygen being absorbed and carbonic acid gas ex- creted. In the female the elimination of the carbonic acid increases up to puberty, remains more or less stationary up to the cessation of the menses, and then declines. Males generally, however, exhale more carbonic anhydride than females. In pregnancy the carbonic anhydride exhaled is increased, but diminished during menstruation. 6. Size and Weight. — Starting at five feet, each increase in height of one inch augments the vital capacity of the lung by about nine cubic inches (eight inches, Hutchinson), and the same applies to an increase in the circumference of the chest (Arnold). But it must be remembered that in the same class of animals the intensity of the respiratory process is greater in its smaller members (Bert). Thin animals absorb in general in the same time more oxygen than fat animals of the same species. 7. Mode of Resjnration. — The frequency of respiration in- creases the total carbonic anhydride expired, diminishing it relatively, however, to the amount of air inspired. Thus with six respirations in the minute 28'5 c.c. COg are exhaled with each expiration, and 171 c.c. in the minute ; while with 12 respirations a minute there are 20'5 c.c. COg in each expiration, and a total of 216 c.c. in the minute (Vierordt). With deep and slow inspirations also more of the gas is expired, and a 1 per cent, increase may thus easily be attained. 8. The State of the Circulation. — A rapid circulation increases the exhalation of carbonic anhydride, as seen in cases of excitement and fever. 9. Cerebral Activity or Repose. — Not only is the temperature of the active organ raised, but the carbonic acid gas exhaled is increased bv mental work. 10. Season and Temperature. — In 100 parts Consuiried Evolved Food Oxygen Wntev by skin and Carbonic anliydride To*,h1 ( Urine and fseces xcrt'tii Nasal secretion December July . 722 1 27-8 75-4 24-6 .s:^-8 36 1 32-3 28-8 33-2 34-7 07 0-4 100 loT) (liARRALL). BESPIRATION. 373 A lowering of the teinpevatui e augments the exhahition of carbonic acid. Tliis is well seen in the next table of Viekordt's, giving the mean of a series of obsei-vations on a man ; the numbers relate to a period of a minute : — AtS-u" At] 9-4° The pulse 72-93 71-21 Tlie resijirations 12-10 11-57 Volume of air expired .... 6,672 c.c. 6,106 c.c. COj expired 299-3 „ 257-8 „ Percentage of C0„ to air expired . . 428 „ 4-0 „ The increase in the exhalation of CO., is accompanied by an increase in the absorption of oxygen, and the increased carbonic acid is due to the intensified oxidation processes necessary to maintain the bodily heat (Theodor, A^oit). With high temperatures, on the other hand, the exhalation of carbonic acid is diminished (Erler), either from injury to the blood corpuscles or from inteiference with the respiratory movement.^. But with cold-blooded animals the carbonic acid is increased up to a certain point, with a rise of temperature. 11. Alterations of Pressure. — Much diminution of the atmo- spheric pressure enfeebles the respiration as well as the general muscular and cardiac activity ; the oxygen absorbed and carbonic anhydride exhaled are also much diminished, and at the same time the urea excreted is lessened. These effects of diminished pressure probably result from the enfeebled tension of the oxygen. If, on the other hand, the pressure is much raised, a sensation of cold is experienced, while the carbonic anhydride exhaled and the oxygen absorbed are diminished. The effects are due to the increased tension of the oxygen. This excess of oxygen, as when compressed air is respired, acts deleteriously ; when nearly double the normal proportion, or about 35 per cent., is present in the arterial blood, it acts as a poison, convulsions and death occurring, as also a lowering of the temperature, indicating a hindrance to the oxidation (Bert). Thus under a pressure of 20 atmospheres, con-esponding to 4 atmo- spheres of oxygen, an animal dies of asphyxia and convulsions. The production of carbonic acid is likewise diminished. At a still higher pressure oxidation is much diminished or ceases entirely, just as under a high pres.'^ure phosphorus will not burn. 12. Species. — Birds consume the most oxygen. The relation of the oxygen expired in the carbonic acid to the oxygen inspired varies considerably also in the pame animal with the nature of the food : thus a bird fed exclusively on vegetables and grain excretes more oxygen in . the carbonic acid exhaled than is supplied by the au- inspiied in the '674: TISSUES, OUGANS, AND liEMAINING SECRETIONS. same period, a proof that in these animals part of the carbonic acid may come directly from the breaking down of the food itself. 13. Disease. — In febrile conditions the temperature is raised, and accordingly is attended with an inci-eased production of carbonic acid. In a case of inflammation in a guinea pig the following results were obtained : — Oxygen ab- Carbonic acid Temperature | sorbed for produced for Proportion each ki)o. of e;ich kilo, of of oxygen in body weight in c.c. at 0° and 760 ram. body weight in c.c. at 0° and 760 mm. the carbonic anhydride to cliat absorbed Of the air In the rectnm of the animal lurirg 1 hour during 1 hour C. P. Normal condition. 948-17 872-06 0-92 18-7° .37-1° 98-7° Slight fever . ns7-3 049-5 0-83 17-5° 38-5° 101-3° High „ . . 1242-6 1201-59 0-96 15-9° 39-7° 103-4° The absorption of oxygen and the production of carbonic acid gas are thus both increased with the elevation of tempei-ature, the respira- tions also being greatly increased in frequency. In febrile conditions there is likewise an increased production of urea and of abnormal quantities of organic bodies jioor in nitrogen or devoid of it. Extensive antesthesia of the sensory nerves leads to diminished respii-atory exchanges. Variations in the Respired Air. — If the proportion of oxygen is not reduced below 17 per cent., different inert gases may be mixed with it without risk, but in a gaseous mixture of 15 per cent, oxygen and 85 per cent, nitrogen sparrows will die in less than an hour. The presence, however, of even a very feeble proportion of certain toxic gases is sufficient to render the air unfit for respiration. When carbonic acid is present in the proportion of 4*5 per cent, the mixture has an aspliyxiating action, but when it rises to 10 per cent, the asphyxia is very rapid. Even the presence of 1 per cent, makes itself felt, and in stables, &c., horses and the like begin to show symptoms of suffocation when the air around them con- tains only 0*3 per cent. It is found that when the proportion rises above a certain amount it tends to be redissolved in the blood and to induce narcotism. Accordingly air containing imich carbonic a<-i(l is unfit for respiration, owing to its inability Ui discliargc the blood of the carbonic acid it contains. With RESPIRA TIOX. 375 an increasing proportion of the gas accumulating in the respired air, a point is soon reached at which the gaseous ex- changes between the blood and the air in the air cells of the lungs either ceases so far as the carbonic acid is concerned, or takes place too slowly and imperfectly to keep the blood sufficiently pure to allow the continuance of the vital processes of the organism. In an atmosphere containing 58*53 per cent, oxygen and 20*09 per cent, carbonic acid gas rabbits die rapidly, although the oxygen present is double its normal amount in the air. But the dangers of a confined and vitiated atmosphere are due not only to the excess of carbonic acid, but also to the accumulation in it of other respiratory products from the lungs and skin. For the mere presence of 1 per cent, carbonic acid in the respired air has very little effect, but an atmosphere in which the carbonic acid has been raised to this proportion by respiration is highly detrimental. Indeed, air rendered so im- pure by respiration as to contain even 0*08 per cent, carbonic acid gas is decidedly unwholesome. In an hour a man will add about 1 per cent, of the gas to about 70 cubic feet of air ; and if the proportion is kept down to 0*1 per cent, at least 700 cubic feet should be supplied to him every hour, or about 16,800 cubic feet in the 24 hours. CHAPTER XXX. PBOSTATE, TESTICLE, OVARY, AND SEMEN. I. The Prostatic Secretion is troubled and slimy, and with an alkaline or neutral reaction ; it contains albumins in very small proportion (0*45 to 0*92 per cent.), and salts, chiefly sodic chloride (about 1 per cent.), also potash and sulphuric and phosphoric acids ; of water there is about 98*5 per cent. But comparatively little, it must be confessed, is known as to the exact nature of this secretion. It probably serves to mix with and dilute the semen. Prostatic calculi frequently occur. These have been found with the following composition : — are tissuus, organs, and remaining secretions. Per cent. Water 80 Organic substances (witli 2 iser cent, nitrogen) 15'8 Lime 37'64 Magnesia 238 Soda 1-70 Potash 0-5 Phosphoric acid ...... 3377 A trace of iron 11. The Testicle. — The watery extract of the fre«li testicle has been found alkaline (Sertoli) and acid (Treskik). Treskin obtained the following bodies in the testicle : globulin sub- stances precipitated by a saturated solution of sodic chloride, kreatin, inosit, leuciu, tyrosin, lecithin, cholesterin, fats, and the chloride of potassium and sodium. Serum albumin, alkali albuminate, and phosphoric acid are probably also present, and glycogen has been found as an inconstant element (Sertoli). In the testicle of salmon Miescher obtained 25 per cent, solids, of which 10*95 to 14*72 are soluble in ether ; these ethereal extractives consist in the 100 parts of — Lecithin . 51-8 to 53-12 Cholesterin . . 13-0 „ 15-76 Fat . 31 -IS „ 33-88 Tlte secretion of the testicles is the semen, Avhich is a white, viscid fluid that is characterised by the presence in it of the spermatozoa, which exhibit marked movements while alive and active. This power of movement they retain for several da^^s in the alkaline fluids of the body, but they soon lose it in acid fluids, or in water, alcohol, ether, chloroform, or strong alkalies. They have much power of resistance against different reagents and do not decompose readily. Spermatozoa. — As their chief chemical components we find nuclein, which appears to form their exterior, contained therein being certain albuminous bodies. Over 4 per cent, of sulphur- containing bodies are also present, and a proportion of water of about 82 per cent. In the nuclein obtainc^l from the spermatozoa of the bull there is 1G*4 i)er cent, nitrogen, together with 7*189 per cent. l)hosphorus, but no sulphur. Mie.scuer gives it the formula PliOSTATE, TESTICLE, OVARY, AND SEMEN. 377 CagH^gNgPgOga- VN'hile the niicleiii obtained from spermatozoa is free from sulphur, the similarly named body extracted from the nuclei of pus corpuscles contains 1*85 to 2*13 per cent, of this element.* In addition to the above lecithin, cholesterin, and fat have also been found in semen. The pure spermatozoa of the salmon have this com- position : — Per ceut. Nuclein . . 48 68 Protamin — a base in combination with the nuclein . 26'7(> Albumins ......... 10'S2 Lecithin 7-47 Cholesterin 2-24 Fat 4-58 The ether extract of the spermatozoa of the hull contains 51 'G per cent, of lecithin, and in the dry spermatozoa there is present 1'18 per cent, of sulphur and 2-36 per cent, of phosphorus, while of ash, containing much phosphate, there is about 5*21 per cent. Crystals also of an albuminous character have been found in the semen, which appear to be of the same nature as Charcot's cry.stals, that are obtained from the splenic pulp and leukajmic blood, &c. They can frequently be obtained by spreading out some semen on a piece of glass and allowing it to dry slowly. It is possible, however, that these crystals may really be derived from the prostatic secretion. According to BoTTCHER they are soluble in water, but shrink up and become opaque and insoluble in boiling Avater; they are readily soluble in alkaline solutions, insoluble in alcohol, ether, and chlorofoim, and ai-e coloured brown by iodine. To the body named protamiii has been assigned the formula CjHooN.-jOg.OH. It enters into combination with platinic chloride, and tinites with some of the mineral acids. An ammoniacal solution of nuclein gives with a solution of a protamin salt a granular precipitate of nuclein-protamin, which is insoluble in water and ammonia, but easily soluble in dilute acids, A body mimed spo- mat in has been described as present ; it is allied to alkali albumin and mucin, and to its presence the semen is said to owe its mucilaginous consistency. III. The Ovary. — The capsule and framework of this gland, like that of the testicle, is fibrous, and yields gelatin when boiled. The fluid in a Graafian follicle contains paralbumin. 378 TISSUES, OIlGAXS, AXI) REMAINING SECRETIONS. From the corpora lutea a yellow pigment {hcemolutein) can be obtained by means of cLloroform, and this extract gives a spectrum with two absorption bands — one well defined and close to F, between it and b ; and a second faint band between F and G. Cysts frequently form in the ovary. Their contents vary some- what, but the fluid is generally turbid, more or leas dark-coloured, and often thready, having a sp. gravity of 1,020 to 1,040, and contain- ing 0'7 to 0*9 per cent, albumin. After this cystic fluid has stood some time a moderate amount of sediment falls, consisting of columnar epithelium, nuclei, cell detritus, and often cholesterin crystals. When it is diluted with water a turbidity appears, and by the addition of alcohol a precipitate is obtained of Scherer's paralbumin, a body not completely coagulated by boiling or by the addition of acetic acid, thus differing from Hoppe Seyler's paralbumin, which is precipitated by acetic and carbonic acids. Very thready fluids genei-ally contain in addition alkali albumin, mucin, mucin peptone, and Eichwald's colloid, a transition form between mucin and its peptone. When boiled with dilute sulphuric acid this colloid furnishes an unfermentable body that can reduce cupric oxide. It is insoluble in water, acetic acid, alcohol, and ether, but soluble in the alkalies and in strong nitric acid ; iodine stains it brown, and Millon's reagent gives it a brownish red tint. In some few large cysts a thin fluid of comparatively low specific gravity is found, containing serum albumin and alkali albuminate, but no paralbumin, and in addition ?ome mucin and peptones. Occasionally the cystic fluid may be clear, watery, and veiy poor in albumins. The largest cysts are found in the broad ligament, and their fluid contents are generally bright, clear, and sligiitly opalescent, weakly alkaline, having a specific gravity of 1002 to 1007, containing little or no albumin, sulphates, or phosphates, and depositing no sedi- ment. Such a fluid contains about 2*2 per cent, dry solids, of which organic constituents form 1'3 (albumin 0'95 per cent.) and ash about 0'94 per cent,, chiefly sodic chloride with traces of sodic and calcic carbonates. 379 CHAPTER XXX I. DEGENERA T 1 N S. The tissues and organs having already been considered in detail, certain degenerations to which they are occasionally subject will here be very briefly referred to. They may be classified into fatty, colloid, Tnucous, amyloid or kn'daceous, pigmentary, and calcareous. But it is often difficult, it may be said, to distinguish between a morbid infil- tration and a degeneration in which the tissue elements are transformed. I. Fatty Degeneration is generally })roduced when the circu- lation in a part becomes insufficient. P^atty granules accumu- late in the corpuscular elements of the tissue, giving them first a granular appearance and then causing them to break down, the protoplasm in its decomposition giving origin to urea, cholesterin, and fatty bodies. In phosphorus poisoning some- what similar effects are brought about in the heart and liver, &c., with an increased excretion of urea in the urine. This direct change of a proteid body into fat has been proved experimentally by placing fragments of muscle or coagulated albumin in the serous cavities of living animals (Wagner), and also by the direct putrefaction of fibrin (WuRTz). The degeneration may be preceded by an infiltration, and in certain acute diseases with a high temperature the tissue elements, particularly the glandular and mucous epitheliums and muscle, are invaded by fine granulations of a proteid nature. If this condition is prolonged the albuminoid infiltration may gradually undergo a fatty degeneration. II. Colloidal Degeneration. — In cells as well as in muscles (as the adductors of the thigh), after certain eruptive fevers, uraemia, &c., an accumulation of homogeneous refracting mate- rial may be often noted gradually replacing the normal tissue, first giving rise to a granular appearance and then to a vitreous aspect. In the follicles of the thyroid a similar colloid degeneration is to be seen. When cells are subjected to this degeneration 38U TISSUIJS, ORGA^'S, AND REMAINING SECRETIONS. they swell up, and after a time lose their outlines ; and in pro- portion as the degeneration proceeds the colloidal material loses its consistency, and becomes a trembling mass very rich in sodic chloride, and consisting chiefly of a non-albuminoid body that is precipitated by alcohol and tannic acid, coloured red by Millon's reagent, and to which the name of colloidin has been given (Gautieh), with the formula CyHj^NOg; it possesses the properties of an amide derivative of the proteids. III. Mucous Degeneration. — Normally a small proportion of mucin is present in some of the tissues ; if this amount is greatly exaggerated, and at the expense of the proper elements of the tissue, we have mucous degeneration. An accumulation of a similar body is found in certain tumours (myxomata, enchondromata, and sarcomata). IV. Amyloid Degeneration is due to the accumulation of a l^ale, waxy-looking substance in the tissues of a part, causing their elements to swell up and their nuclei to atrophy, and after a time their different elements to fuse into irregular blocks. The organs most subject to this change are the liver, spleen, kidneys, suprarenal capsules, and the walls of blood vessels, &c., and it is produced most frequently in persons who have been subject to syphilis, tubercle, carcinoma, or long- standing purulent discharges. The amyloid substance contains 15*5 per cent, nitrogen and 1*37 per cent, sulphur. All its reactions seem to show that it is a mixture of a series of bodies closely allied to albumin (Gautiek), although it has long been regarded as a special form of albumin. (For its characters see p. 122.) V. Pigmentary Degeneration. — The pigment is not always the same, but it is probably a derivative of haemoglobin decom- position. An abundant formation of this pigment occurs in melansemia, Addison's disease, and melanic cancer. The pigment occurs in the form of small dark granulations. The name melanin has been given to it. It dissolves slowly in caustic potash, forming a brownish red solution, and corre- sponds in composition to the normal pigment of the eye. Tlu; ])igment may also occasionally show itself in the foini of crystals of ha-maloidin. In the disease named chrohi- hydrusis this ])igin( ul is eliminated with the sweat. DEGENERA TIONS. P,%\ The following is an analysis of a melanotic tumour (Eiselt and Bolze) : — Albumin . . 3-28 Soluble pigment . 20 Insoluble tissues . 7-92 Salts . 10 ,, pigment . . 3-3() Water . 82-4 YI. Calcareous Degeneration.^As the result of irritation of different kinds, of general or local disturbances of nutrition, and of senile atrophy, &c., there may ensue an infiltration of mineral salts into many of the tissues, particularly into the coats of the blood vessels and into costal cartilages, giving rise to the appearance of calcification. The deposit consists chiefly of carbonate of lime mixed with phosphate of lime and traces of salts of magnesia. The new formation contains no ossein and presents no ossific structure. CHAPTER XXXII. MILK. Physical Characters. — Milk is an opaque whitish fluid, having an opalescent, bluish tiut in thin layers, and a sp. gravity varying between 1018 and 1045, or averaging between 1028 and 1034 (Simon) ; it is a natural emulsion, consisting of little globules of fat invested with coatings of casein and suspended in a solution of albumin, milk sugar, and salts. The reaction of milk is variable, woman's milk and that of the herbivora being normally alkaline, but that of carnivora acid ; with the milk of herbivora, however, it is often possible to obtain a double re- action, both acid and alkaline, owing to the presence of an acid sodic phosphate (HjNaPO^) and of an alkaline disodic phos- phate (Na2HP04). Milk becomes acid on standing, owing to the conversion of part of its sugar into lactic acid ; and at the same time the fatty globules rise to the surface, forming a layer of cream, some of these globules possibly also being freed from their protein envelopes ^^Muller). The so-called uterine milk is a white or rosy-coloured, creamy, alkaline fluid, having a density of 1033 to 1040, which is obtained 382 TISSUES, ORGANS, AXD liEMAIXIXG SECRETIONS. by gentle compi'ession of the placental cotyledons of ruminants. It quickly becomes acid and coagulates. Fatty particles, free nuclei and epithelial cells are present in it. This has been assigned as its composition in the case of the cow : — Water .... 87-91 \ Albumin and cells . . 1040 Solids .... 12-09 AlbumiDate . . . 0-16 (Fat . . . . 1-23 j Ash .... 0-37) In most new-born mammals the mammge may secrete a little strongly alkaline fluid during the first month, which con- tains about 96 per cent, water, 1'4 per cent, salts, 0*9 percent, sugar, 0"55 per cent, casein, and 0'49 per cent, albumin. Amount Secreted. — From the third to the sixth month of lactation a woman secretes each day about 2 to 2^ lbs. of milk ; but the amount is very variable, and may be taken as an average of If pint daily. A good cow gives about four times its body weight of milk in the year, or about six to seven litres (ten to twelve pints') each day. Chemical Composition. — The milk contains dissolved and suspended constituents ; the latter are the corpuscles or globules which consist of particles of butter enclosed in minute casein envelopes, ^-sVo ^^ roVo ^^ ^^ i^^^ i^i diameter, though some of them may be as small as -^ o ^ „ q (Fleischmann). For a few days after parturition colostrum corpuscles, which are accumulations of fatty particles of a pale yellow colour, TijV(7 ^o 8^-(r of an inch in diameter, are also present. A few epithelial cells may likewise be met with. With regard to the existence of the casein envelopes as distinct membranes, it should be mentioned that some doubts have been expressed by several observers (Zahn, &c.) ; but if the milk is first mixed with a little caustic potash, and then well shaken with ether, the fat will be dissolved up by the latter— indicating, at any rate, the existence of an albuminous envelope of some kind. The casein, sugar, and fat are formed in the cells of the mam- mary gland, chiefly, no doubt, at the expense of the proteids, by a differentiation probably of the serum albumin. The secre- tion appears to bear a direct proportion to the production of chyme. MILK. 383 1. Sidids ill a Pint of MUh. Grams Nitrogenous constituents. . 23'J Fatty . 227 Saccharine ,, . 30-3 Salts . 40 II. ComjJOiiition of the Milk of Different Animals (after GORUP Besanez, LiKBERMANN, GAUTIER, &C.). Constituents Woman Ass Cow Goat Sheep Mare Colostnmi 1 Water 86-27 88-91 87-77 84-08 90-70 86-56 86-76 83-30 82-84 Solids 13-72 11-09 12-23 15-92 19-30 13-44 13-24 16-69 17-16 Casein . Albumin ;- 2-9.5 3 92 2-34 323 1-70 3-50 0-58 2-92 1-31 [5-73 1-64 Butter . 5-37 2-67 3-68 .5-78 1-55 4-03 4-48 6-05 6-87 Milk suo:ar . 5-13 4-36 5--o5 6-51 5-80 4-60 3-91 3-96 1 . „ 0-68 ) ^ ^^ Inorganic salts 0-22 0-14 0-23 0-35 0-50 0-73 0-62 In the case of colostrum the deficiency is in the casein, there being an excess of the other albumins. In woman's milk the proteifls may vary from 1*1 to 4* 19 per cent. ; in one analysis ToLMATSCHEFF obtained 1-28 per cent, casein and 0-34: per cent, albumin. III. The Ash of Milk in 100 Parts. (a) Woman's milk Cow's milk (WlLDENSTKlN) 4-21 (WEBEI!) (Haidlex) Sodium . 6-38 8-27 Potassium 31-59 24-71 15-42 Chlorine . 19-06 14-39 16-96 Calcii;m . 18-78 17-31 Magnesium 0-87 1-90 '- oG-52 Phosphoric acid 19-00 29-13 ) Sulphuric „ 2-64 115 Ferric oxide . 0-10 033 0-62 Silica trace 0-09 The potash salts, it will thus be seen, exceed the soda salts, the inverse of which holds srood in the serum of blood. (/3) (Vernois and Becquerel.) Salts insoluble in water . 77-5 per cent. soluble 22-5 j phosphate of lime, with j traces of other salts ^ carbonate of lime . ( sodic chloride „ sulphate ^ other salts r006 6-9 9-8 7-4 .5-3 384 TISSUES, ORGANS, AND REMAINING SECRETIONS. Of ash in cow's milk Bunge obtained 08 per cent., of which 22-14 per cent. = ¥.^0, 24-75 per cent. = phosphoric acid, 21-3 per cent. = chlorine, 2005 = CaO, 13-9 = NagO, 2-63 = MgO, and 0-04 = FeaOg. Human milk is therefore much richer than cow's milk in potash salts. IV. The Rclatire Value of B\fferent Kinds of Milk. Casein ami Water albumin Butter Sugar and sa'ts Mare's milk 9115 103 127 6-12 Ass's „ 89-01 3 -.57 1-85 5-57 Woman's „ 87-24 2-88 3-68 5-78 Goafs „ 86-8.-) 3-79 4-34 3-78 Cow's „ 84-28 4 3.5 6-47 4-34 Sheep's „ 83-30 573 «05 3-96 («) V. Condensed Milk. Per cent. Water 29 to 24 Solids 71 „ 76 Casein ..... 16 „ 18 Fats 9 „ 13 Milk sugar . . 8 ,. 18 Cane „ . . . . 27 „ 29 Ash 2 „ 2-5 Phosphoric acid 0-2 „ 0-7 (^) Swiss Condensed Milk — without added sugar, but with added benzoic acid (Fleischmann). Lactose . . . 17-43 Water . Fat . Albumin 52-31 13 09 12-13 Ash . Benzoic acid 2-78 1-74 VI. Gases of Milk (Pflugbr) (at 0° and 1 metre pressure). In 100 volmnes of milk In 100 volumes of gas Carbonic anhydride . . 7 CO 90 48 Oxygen .... 010 119 Nitrogen .... 0-70 833 The constituents of milk, therefore, aYe]07-oteids, principally casein with a little serum albumin ; fats, as olein, much palmitin, much le.ss stearin, and about 2 per cent, of the total fats as triglycerides of butyric (C^HgOg), caproic (CgHj^Og), caprylic (CgHjeOj), with traces of myristic (Ci^HjgOg) and arachidic (CjoH^o^,) ^^^^*^5 some of these last probably not being present MILK. 385 in fresh milk ; milk sugar or lactose, which varies least in quantity; and extractives and salts, chiefly potassic phosphate and chloride, and calcic phosphate, with traces of cholesterin and lecithin and of a body resembling lutein. But analyses show that great variation exists in the composition of milk, as is well seen in the case of cow's milk (Borries). Woman's milk contains 87 to 90 per cent, of water, in which we find casein, serum albumin, a body like lacto-protein (Millon, Liebermann), together with fats, milk sugar, extractives, and in- organic salts. The lacto-pj-otein body is not precipitated by boiling, by acids or mercuric chloride, but only by the acid nitrate of mercury. HOPPE Seyler regards it as a mixture of serum albumin and casein. Nasse maintains that casein contains more loosely combined nitrogen than other animal albumins, Lubawin considering it closely allied to nuclein. According to Eadenhausen, when human milk is shaken up with ether it loses its opacity, which is not the case with cow's milk, this latter requiring the previous addition of caustic soda to bring about the same result. He is further of opinion that the casein of human milk is not true casein, but rather an albumin. Traces of peptone were also found by him in human milk. The casein of woman's milk also is not so easily precipitated by acetic and carbonic acid as that of the cow, and it forms a gelatinous mass difficult to filter ; sulphate of magnesia, however, precipitates it more readily and completely. Coio's milk contains some exti-actives that are said to be wanting in woman's milk : among these are urea (0'015 per cent.) and traces of kreatin ; also acetic acid (0004 to 0'014 per cent.) and alcohol — 800 c.c. ass's milk yielding 30 c.c. of a distillate containing 3*5 per cent, alcohol and 0036 giam acetic acid (Bechamp). Two diflerent caseins are likewise mentioned, one soluble and the other insoluble (Selmi), and a trace of gelatin is also described. The casein is an acid body (Rochleder), which in the pure form is scarcely soluble in water, but in milk it is combined with a soluble alkali albuminate. Calcic phosphate also serves as a solvent medium for the casein of milk. The relative proportions of casein and albumin in milk ai-e (Makris) casein, 1-87 to 4*68 per cent.; albumin, 0-60 to 1*77 per cent. In addition to serum albumin another albumin is described as present, having the composition C = 52'9, H -— 6*7, N=14-4; it is nut precipitated when the milk is c c 386 TISSUES, ORGANS, AND REMAINING SECRETIONS. acidified with acetic acid and a current of carbonic acid gas passed through it, nor is it coagulated by boiling. A considerable amount of nitrogenous matter, apart from the casein and albumin, is contained in milk (Hoppe Seyler); in human milk it varies between 0*3 and 0*5 per cent., and in cow's milk it is about 0*7 per cent. Danilewski describes three albumins in the whey of milk, the chief one being identical with the stroma albumin of the milk globules ; the second an albumin of albuminoid character, named orroprotein ; and the third being peptone. Milk sugar is one of the characteristic constituents of milk, and butter the most variable one. Coagulation of Milk. — Milk, even when just drawn from the cow, contains living organisms derived from contact with the udder, the hands of the milker, or the vessel in which the milk is collected. These are aerobia, which take up oxygen from the air and produce diastases that coagulate the casein. If a few drops of indigo-carmin solution are added to new milk filling a stoppered bottle, the colour soon disappears, but is restored again on exposing the milk to the air. The coagulation which is due to a deposition of the casein may occur spontaneously when the milk turns sour, or after the addition of rennet or of vegetable or mineral acids to warm milk. Tannin, alcohol, the salts of the heavy metals, and many neutral salts of the alkalies produce the same result. But Hammarsten affirms that a pure salt-free casein solu- tion gives no permanent precipitate even when strongly acidified, and that also for its coagulation to be effected by rennet the presence of phosphate of lime is indispensable ; further, that when it is coagulated by rennet two new albumins are formed, one being a cheesy body soluble with difficulty in water, and the other a whey albumin that is easily soluble. The spontaneous coagulation takes place in one of two ways. It is generally preceded by the formation of lactic acid from the milk sugar by the lactic ferment, the action of which is destroyed by neutralisation of the milk with a few drops of sodic carbonate and then boiling, or by the addition of borax. But spontaneous coagulation may set in without MILK. 387 the milk turning sour ; it is not then due to the hictic ferment, but to aerobia acting as casein ferments and active producers of diastases. This coagulation is not always arrested by boil- ing, even after the addition of sodic bicarbonate. As these ferments are most active at 40° to 45°, if the milk can be heated to this i)oint without coagulating the temperature may then be raised to 100°, when the ferments will be destroyed (DUCLAUX). When milk is boiled and allowed to evaporate, a scum or pellicle of insoluble casein forms on its surface, which is renewed on its removal. Colostrum, sow's milk, and the milk of canii- vora coagulate when heated. The presence of small quantities of sidts, such as sodic and potassic chloride and acetate, &c., prevents to a certain extent the precipitation of casein by acids ; so it is possible that when acid is added to a pure solution of casein minute traces of salts may be generated by the action of the acid on the casein. The coagulation by acid is probably a precipitation of the casein by a neutralisation of the solvent alkali ; but for the acid to effect precipitation it must be added beyond the point of neutralisation. Milk that has been boiled coagulates spontaneously with difficulty, but after having been acidified it does so more readily than unboiled milk. Boiled milk is also more difficult to coagulate by rennet than fresh unboiled milk. Fresh milk is not coagulated by boiling even after a current of carbonic acid has been passed through it, but if the milk has stood some time coagulation will be thus produced, while if a sufficient time has elapsed, and a sufficiency of lactic acid has been developed, boiling alone will effect the coagula- tion ; later still a current of carbonic acid will coagulate the milk, and finally the milk will set of itself, the coagulum con- sisting of casein and fat, and the whey of a solution of milk sugar, lactic acid, and inorganic salts, with a little fat, albu- min, and traces of casein. Heat accelerates the process con- siderably. Eennet, we have seen, causes milk to coagulate, and this occurs whether the milk is weakly acid or alkaline, and more rapidly at a moderately elevated temperature than at a low c c 2 388 TISSUJES, OBGANS, AA'D REMAINING SECRETIONS. temperature ; but it coagulates with difficulty if it has been previously heated to 75°. Milk as it comes from the cow has a temperatm'e of 37° ; the ordinary temperature at which coagulation occm's is 25° to 35° ; at 65° the diastase of the rennet is destroyed, at 10° pure rennet may be left in contact with sterilised milk for an indefinite time without causing coagulation, and at 41° the maximum effect is produced. The addition of a 1 per cent, sodic chloride solution causes the curdling to be more rapid; the same occurs also with a dilute potash solution, whereas with a 4 to 10 per cent, sodic chloride solution it is rendered much slower. An active rennet may he thus fre-pared : The stomach of a young calf is rapidly washed in plenty of cold water, then distended with air, and hung up in a dry place for two or three months. All the walls, except a small portion round the pylorus, are cut up into small pieces and macerated for two or three days in six times their weight of sodic chloride solution (5 per cent.) ; more of the same saHne solution, or some 5 per cent, boric acid solution, is next added, the whole allowed to stand for some time, then decanted and filtered. The filtrate is to be preserved in the dai-k in full bottles tightly corked ; or seven to eight times its volume of alcohol may be added to it, the precipitate filtered otf after twelve hours, and dried at a gentle heat. This last keeps well and may be dissolved in water when required (Duclaux). One part of this dry mucus, which need not contain more than 10 per cent, diastase, will cause 200,000 parts of milk to coagulate in 4.5 minutes at 37°. Free lactic acid liberates the casein from its alkali com- bination, and accordingly rennet acts more completely on a milk that has stood some time, in which part of the milk sugar has fermented ; but the coagulation of the casein by rennet and by lactic acid are not to be regarded as identical. Milk, it may be said, contains a lactic acid ferment, or a body that is readily converted into it; it is precipitable by alcohol. Alterations in Milk 2^rorJvced by Exposure to the Air, Aye oj the Aniitud, Character of the Food, &c. (a) Exposure to the Air. — Milk exposed to tlie air ahsorbs in three days more than its own volume of oxygen, part of its casein being transformed at the same time into butter (Hoppe Seyler) ; MILK. 389 and by degrees the milk turns acid from the production of lactic acid at the expense of the sugar. When the lactic acid rises to 4 per cent, it ceases to increase. If the milk is frequently agitated in the air, alcoholic or even butyric fermentation may be set up. Boiling retards the acidification, and the same results from the addition of thymol and boracic acid or its glyceride. (b) Age and Habit. — In women's milk comparatively little differ- ence seems to exist between the ages of 20 and 35, although after 20 it is said to become somewhat thinner, containing more water and less casein and butter. Before the age of 20 the milk contains more salts, casein, and butter than later in life ; and after fet. .35 it is a little poorer in salts, the other elements apparently reinaining un- altered. It has also been stated that women of spare habit secrete a milk richer in solids (as casein, &c.) than women of robust habit, and that the milk of brunettes is richer in casein, butter, and milk sugar than the milk of blondes (L'Heritier) ; bub no difference has been observed by others (Tolmatscheff). The milk of a mother after her first child is said to contain less solids than that secreted after subsequent confinements. (c) Duration of Secretion. — Milk secreted by the mother the first three or four days after parturition contains an excess of fat and is named the colostrum. This is a slimy, yellowish, alkaline fluid, having a specific gravity of 1040 to 1060, which on standing separates into two layers ; compared with ordinary milk it is richer in fi\t, milk sugar, and salts. Shortly before parturition the human milk contains about 14 per cent, solids, about 2 per cent, butter, and 3^ per cent, sugar ; but about 24 hours after delivery nearly 16 per cent, solids, which diminish about 1 per cent, every few days till the twelfth day, when they average about 9 '5 per cent. Two days subsequently to parturi- tion the butter averages nearly 5 per cent, and the sugar 6 per cent. — proportions that diminish rapidly to the normal (Clemm, &c.) During the first five months the salts are in excess, and then progressively decrease to the eighth month, when they increase slightly ; the casein and extractives diminish up to the second month, and then remain nearly constant, but from the tenth to the twenty- fourth month the casein declines ; from the eighth to the tenth month the sugar increases, this body being in small proportion during the latter part of the first month ; and in the fifth and sixth, and tenth and eleventh months the butter falls in propoi-tion, progi'essively diminishing from the first to the eighth month, and then increasing slightly. sno TISSUES, ORGANS, AND REMAINING SECRETIONS. After suckling is given up the solids rapidly fall. The milk secreted after a long period of lactation is generally poorer in casein and richer in other albumins than the milk secreted at an earlier period. {d) Influence of Frequent Removal of the Milk, Time of Day, Season, d'c. — The less frequently the milk is taken from the mammary gland the greater is its proportion of water, the last portions removed being generally the richest in butter, generally containing seven times more than the milk that comes away at first — due probably to the gi'eater degree of agitation to which this last portion has been subjected, and possibly also to its coming from the finer canals. In mammals it has been observed that the evening milk is neaily twice as rich in butter as the morning milk. If a cow is milked three times a day, the proportion especially of casein and of butter is higher in the evening, the salts remaining about the same (Bodecker) : ]\rnniiiig Midday Evr-ning Sp. gravity 1(138 1040 103(i Water 8'.)i) 89-2 8R(J Solids 10 I 10-8 13 4 Casein . 2-24 2-3(i 2-72 Sugar . 4-30 4-72 4-1!) r.ntter . 2-17 2-03 5-42 Albniiiin 44 0-:52 0-31 Ash . 0-83 0-6!) 0-78 1 (Fleischmann •) jroniiiig Evening Sp. gravity Percentage of fat . Yield for each cow in kilos. 1031-6 " 3.37 3-6.'52 1031-8 3-42 3-431) According to Eklenmeyer, however, midday milk is the richest in fat, and morning milk the poorest, because of the greater quantity of milk that has been formed since the previous milking. Fleisch- mann state.^, as the result of observations continued over three years, that in morning milk the fat, dry solid.s, and sp. gravity are lower than in evening milk, the difierence being slight but constant. In summer the milk is more abundant and richer in butter than in winter. (/?) The Food. — While the quality of the food does not seem to exercise much influence on the character of the milk, the quantity apjjears to do so (Decaisne). Yet, according to some authorities, a MILK, 391 food rich in proteids increases the butter and sugar (SuBJiOTiN, Weiske). An exclusively animal diet increases the albumin at the expense of the casein. Abundance of food increases both casein and fat, while a lessened diet diminishes the total solids with the exception of the albumin. (y') Eetit seems to encoui-age the formation of butter, exercise impoverishing the milk in butter, but enriching it in casein. The emotions appear to exercise considerable influence on the character of the secretion. During menstruation the milk is richer in solids (Roger), but it appears to contain less nutritious principles and is more liable to excite gastric disturbance in the infant. Probably the chief chemical alteration consists in the diminished proportion of sugar. BUTTER. — Cow's butter contains about 68 per cent, palmitin and stearin, 30 per cent, olein, and 2 per cent, special fats (Bromeis), and the solid fats appear to be more abundant in winter than in summer (Braconxot). But the standard pro- portion of fixed acids in genuine butter fat has been variously fixed by different chemists — 87-5 per cent. (Hehner), 88 to 88-36 per cent. (Bischoff), 89*73 per cent. (Fleischmann). The amount of fat in cream is also said to vary very much, from 14 to 44 per cent. (Wanklyn). By mechanical agitation the butter can be separated from the milk globules. This is effected most readily at a tempera- ture of about 14°, after the milk has become slightly acid, and when the strokes of the instrument used in producing the agitation do not exceed 30 to 40 in the minute. To this operation the word ^ churning^ is applied. About two -thirds of the milk fat can thus be obtained as butter, the other kind remaining behind in the buttermilk. 100 kilos. (220 lbs.) of milk, furnishing a mean of 15'6 kilos. (34 lbs.) of cream, yield 3 to 4 kilos. (6*6 to 8*8 lbs.) of butter. The butter thus prepared may contain as much as 18 per cent, casein ; it melts between 30° and 40°, and is readily soluble in alcohol and ether. By exposure to the air and direct sunlight butter becomes rancid, owing to the development of fatty acids, glycerin, acrolein, and formic acid, &c., making their appearance. The peculiar smell and taste of rancid butter is generally 392 TISSUES, ORGANS, AND REMAINING SECRETIONS. assumed to be due to the presence of free butyric acid, but accord- ing to Hagemann this does not seem to be the case, being due more likely to tlie formation of lactic acid by a process of fer- mentation from the milk sugar contained in the butter. The Preservation of Milk. — A number of different bodies like salicylic acid, ether, chloroform, phenol, boi-ate of soda, and boro- glyceride, when added in small i^roportion to milk, tend to preserve it ; but this preservation is best effected by evaporating the milk to a thick syrup under a reduced pressure, and adding to it a considerable quantity of cane sugar ; this on dilution gives a fluid corresponding to the original milk, except in containing more saccharine matter. Biyestibility of Casein. — Rennet precipitates casein in compact masses both from raw milk and milk that has been warmed a short time at 50° to 70°. If the milk is boiled or kept two hours at 70° (Becker's method of milk preservation) a fine flocculent curd soon forms with i-ennet. Digestion experiments with artificial gastric juice and subsequent colorimetric determination of the peptones show that Becker's preparation yields most peptones, boiled milk coming next, and raw milk yielding least. Substitutes for woman s milk have been proposed for children. If we compare woman's milk with that of the ass and cow we find — Woman Ass Cow Casein . 2-7 1-7 4-2 Butter . . 3-5 1-3 3-8 Milk sugar . 5-0 4-5 3 8 Salts . 0-2 0-5 0-7 (Frankland). Therefore the proportion of casein in cow's milk is too high and that of milk sugar too low. In the substitutes proposed an attempt is made to obviate tliis. But it should be remembered that the ca.sein of woman's milk does not appear to be exactly identical with that of cow's milk. IT. Unskimmed milk 600 grams Creara of milk .... 13 „ Cry.stallised sugar of milk . 15 „ Phosphate of lime (recently precipita oA) 1 •.'■) „ Wat«r 339-5 „ (COULIER) Wheat flour 1 oz. Malt „ 1 ,. I'otash Ijjcarbon.ito . . . . 14i grains .Mix well anil ailil Water 2 oz. Cow's milk 10 „ MILK. 303 Warm tlie mixture, with continuous stirring, over a very slow fire till it ])econies thick, then remove from the fire and stir well for five minutes ; put it on the fire again and take it off as soon as it gets thick ; finally let it boil well. It should form a thin and sweet liquid previous to the last boiling. Before use strain through muslin. III. Heat half a pint of skimmed milk to 35°, and add to it a little rennet ; let it stand in a warm place, either over a lamp or in some hot water, for ten minutes or so. Break up the curd finely with a knife, and after a quarter of an hour strain the whey through muslin and boil it in a small saucepan, adding to it 110 grains of powdered sugar of milk. Strain again through muslin, and when quite cold add to it two-thirds of a pint of milk fresh from the cow, and two teaspoonfuls of cream, stirring well together. The milk obtained should be kept in a cool place ; a little of it is warmed when required, but it must be freshly prepared every 12 hours (Frankland). Pathological Alterations in Milk. Drugs, d-c. — Salts of iodine, antimony, and arsenic rapidly appear in the milk after their adminis- tration ; also salts of mercury after heavy and rei>eated doses, though this is denied (Kuhler). Boric acid, chlorides, alkaline carbonates, and salts of iron, lead, and zinc may likewise appear ; also the organic acids, morphia, and other alkaloids. The ingestion of certain poisonous plants and of damaged grain affects the milk injuriously. In certain morbid coiiditioiis there is an increase of the albumin at the cost of the casein. In osteomalacia the lime salts are increased. Blue milk has been observed containing a coloured vibrio. Blood and pits may be present. The contour of the globules may be altered and not sharply defined, and their number lessened {as in ' distemper ' of cows). During aciUe fevers the secretion of milk decreases, the casein increasing, but the sugar and fats diminishing. In chronic diseases the proportion of casein falls slightly, while the butter and salts increase, the sugar remaining constant. In tubercular consumj)tion it is said that the milk acquires a peculiar infective taint. In syphilis the salts are doubled, but the casein and butter are diminished. In different cachexias the nutri- tive qualities are lessened. In the rinderpest in cows the milk is often of a reddish yellow colour; it may contain blood and possess a nasty taste ; the proportion of butter and sugar may sink to one-third the normal, while the albumin and salts may be increased to three times their ordinary amount, the casein also being doubled. Husson found the following percentages : casein 5*02, albumin 2"06, fat 1-26 to 1-49, sugar 1-64 to 3- 14, salts 1-85. . 304 TISSUES, ORGANS, AXD REMAINING SECRETIONS. CHAPTER XXXIII. THE ANALYSIS OF MILK. Physical Characters. — Good covv's milk is white with a faint yellowish tint, or when diluted it is bluish white ; it has a fatty and not a watery feel between the fingers ; if undiluted a drop of it placed on the thumb nail retains its shape instead of rapidly spreading out, which it is very likely to do if it has been diluted or if it proceeds from an unhealthy source. Its sp. gravity should not be lower than 1018 or higher than 1045 ; an average of 1029 to 1033 at 15° is given by some authorities. The reaction is generally alkaline, though at times it is ampho- teric, and occasionally while the first of a milking is alkaline the last of it may be acid. TESTS.— I. Qualitative. 1. Examine a drop under the raicroacojje and note the globules ; then add a drop of acetic acid, and on moving about the cover glass the globules will be seen to ®o °°^ oQ, coalesce, owing to their casein coatings hav- o ® °9o ^ "^ o°o i"g been dissolved. In addition globules of -° ooo°oV'^ ^^^® ^^^ ^^y ^^ ^^^^ ^^^ large granular Qg)'^^^ fS ' " " f^tty cells (particularly in human milk after *"'° o^® ® parturition), also fine free granulations con- FiG. 27.— mjlk ou,- sistinsr chiefly of casein and nuclein, and dis- appearing on the addition of caustic potash. 2. Take the sp. gravity. As the hydrometer or lacto- meter is generally graduated for a temperature of 15°, the milk should be brought to this point if accurate results are reqiiired ; otherwise a correction must be made. Normal cow's milk is said to indicate 1028 to 1034. Dilute some normal cow's milk with half its volume of water and take the sp. gravity: it will vary from 1014 to 1016. The following numbers have been given, but they are pro- bably a little too high : — Witli skiiiinifd JT)i)k tJnsliimm(:il milk A i-p. giaviiy of l(i:{7 1o 1( :i:^ or 10:'..'5 to 1020 indicates a pure milk „ „ 1(j:^:J „ 101'9 „ 1029 „ 1026 „ milk with 10 per cent, water THE AyALVSIS OF MILK. 395 Witli skimmed milk Vnskiinmed milk A sp. gravity of 1029 to 102G or 102G to 1023 indicates milk with 20 per cent, water 1020 „ 102:} „ 102:} „ 1 020 indicates milk with 30 per cent, water „ „ 1023 „ 1020 „ 1020 „ 1017 indicates milk with 40 per cent, water 3. Separate the casein by diluting tlie milk, acidifying slightly with acetic acid, and heating up to 60° or 70° ; but by heating to 80° the flocculent precipitate becomes more marked, and a more complete separation of the casein is effected by sub- sequently passing a current of carbonic acid gas. The greater part of the butter separates with the casein. To detect it wash the casein precipitate with water, exhaust the washed mass with a mixture of alcohol and ether, and evaporate the extract thus obtained. Boil the filtrate from the first casein precipitate, or add to it potassic ferrocyanide, and a 'precijpitate of the serum albumin will be obtained. 4. To Separate the Butter. — Add to a little milk contained in a long cylindrical tube half its volume of caustic potash solution (10 per cent.), and then shake the mixture rapidly with twice its volume of ether. Next insert the tube in a vessel containing hot water ; the ethereal solution accumulates at the toj) of the fluid in the tube, and when it evaporate.s leaves a layer of butter behind. Or take a long graduated tube closed at one end and fill it one- fourth with milk, one-fourth with ether, and another one- fourth with spirit (about 86 per cent.) ; cork it, and having shaken it well leave the tube inverted for some time at a temperature of about 40° imtil an oily layer has formed and appears not to increase. By this means a better estimate can be formed as to the amount of butter present. 5. Separation of the Globules by Filtration and Detection of Albumin in the Clear Filtrate, — By means of a reduced pressure filter milk through porcelain (p, 1 1 ) ; the globules will be stopped and a clear fluid will pass through containing albumin. Show this by testing the clear filtrate successively by boiling it and by the addition of nitric acid. 6. To Detect the Surjar. — Warm some milk, after the addi- tion of a few drops of acetic or hydrochloric acid, to 40° ; filter 30C) TISSUES, OEGAXS, AND ItEMAIMNG SECRETIONS. after some time through a moist plaited filter ; shake the filtrate with ether, to separate the fat completely ; then boil it to coagulate the dissolved albumin ; filter, and evaporate the filtrate to a thick syrupy consistence, when the lactose will be gradually deposited in a crystalline form. 7. Tincture of guaiacum added to a drop of fresh milk in a watch glass produces an intense blue coloration at once or after a few seconds. Milk that has been boiled remains un- coloured. II. Quantitative. 1. The Solids. — (j) To 10 grams dry sand or powdered gypsiun add 5 c.c. milk, then dry the mixture for a long time at 100° until the weight is constant. The increase in weight is equal to the solids in 5 c.c. milk. Suppose this to be = 0'5 gram, then 100 c.c. milk contain 10 grams, or 10 per cent, solids (Baumhauer). Instead of 5 c.c. 10 grams of milk and 20 grams of dry sea sand may be weighed in a tared capsule of about .50 c.c. and evaporated at 100° till the weight is constant. When quite cold the capsule, with its contents, is weighed in a desiccator over sulphuric acid. (ij) Place a little milk in a platinum capsule, and having weighed it, add a few drops of alcohol or acetic acid ; evajiorate over a water bath, dividing the coagulum against the sides of the dish, and dry it at 100° to 110° until the weight is constant. It is generally com- pleted in six hours (Gerber). Cover cai'efully before weighing, as the residue is very hygroscopic. The total solids should not, as a rule, be much less than 11 -.5 per cent.; cow's milk, for example, varies between 10"5 and 1.5 per cent. ; less than this indicates dilution. 2. The Butter.— {]) Shake the milk well, and to 20 c.c. of it add 20 c.c. of a 10 per cent, caustic potasli solution, and then some ether (GO to 100 c.c), and agitate vigorously for some time ; on standing the ethereal solution of the liberated fat rises to the surface, and is to be carefully decanted into a weighed porcelain dish. Some more ether is to be added to the alkaline milk, and after vigorous agitation it aLso is to be transferred as before to the capsule. The same process may be repeated several times if necessary. The ethereal extract is now evaporated over a water bath, and after having been dried in an air bath at 110° the weight of the residue is to be ascertained ; this multiplied by .5 gives the pei'contago. With cow's milk it varies between 2 and 5 per cent., but the normal minimum for- fats is about 2-75 (Cameron). THE AyALY.SLS OF MILK. 397 (ij) An ajijiroximative deter tnination may also bn made bj means of a graduated narrow glass cylinder or lactometer divided into 100 degrees from at)ove downwards. The milk, well shaken, is poured into this vessel until it stands at 0° ; the whole is then laid aside for 24 hours at a temp, of 10° to 12°. The cream rises to the surface and forms a layer, the thickness of which is to be read off at the end of this time. Good milk should yield from 10 to 1.5 2)er cent, of cream. (iij) Determination hij the Ojytical Method. — Both the following processes are founded on the determination of the degree of opacity of milk, which depends on the number of globules present. (rt) With the (jnldctoscope of Donxe the light of a candle is examined in a dark room through a variable length of column of milk until the light is occluded, and from the length of column at which this occurs the richness of the milk in corpuscles is estimated. {h) Vogel's milk test consists in the addition of small measured portions of milk to 100 c.c. of water, until a portion of the mixture transferred to a glass test vessel with parallel walls 0'.5 cm. apart renders it opaque to light. The percentage of fat is obtained by the 23-2 formula x =■ — + 0'23, n being the number of c.c. of milk re- H Cjuired to produce the opacity. A cylindrical bottle is nsed in which to mix the milk and water. 100 c.c. of water is first placed in this bottle, and then by means of a finely graduated pipette 3 c.c. of milk added, and the two shaken together. The glass test vessel is then filled with the mixture and placed in a darkened room, about a metre in front of a stearin candle. If the image of the flame can be seen through the layer of liquid, then return it to the bottle and add 0"5 c.c. more milk to it ; shake the bottle and repeat the experiment. This is to be continued until the outlines of the flame can no longer be seen through the layer of fluid in the test vessel. G c.c. pure cow's milk forms a mixture with 100 c.c. water which completely obscures the flame of a candle in a darkened room. When more milk than this is required dilution with water is indicated : thus when 12 c.c. are needed 50 per cent, too much water is jjresent in the milk, and when 8 c.c. about 30 per cent. 3. The Casein and Albumin. — j. (a) Dilute 20 c.c. milk with 400 c.c. water and treat the mixture with very dilute acetic acid added drojy hy drop until a flocculent jyredjyitate begins to appear. Now pass a current of carbonic acid gas through the fluid for 1.5 to 30 minutes, and lay aside for one to two days. Collect the precipitated 398 TISSUES, ORGANS, AND liEMAINING SECRETIONS. casein on a weighed filter, wash it with spirit and then with ether until a drop of the washings leaves no fatty stain on paper; dry at 100° and weigh. Subtract the weight of the filter, and the diflerence multiplied by 5 gives the percentage of casein. In the case of human milk precipitate the casein by saturating with magnesia sulphate. (h) The filtrate from the casein pi'pcipitate is to be concentrated to a small bulk over a water bath, and an acetic acid tannin solution added so long as any precipitation occurs ; and after the precipitate has settled collect it on a weighed filter, where it is to be washed with dilute spirit until the filtrate gives no blue coloration with ferric chloride (indicating absence of tannin) ; dry now at 100° and weigh. The weight multiplied by 5 gives the percentage of albumin. In cow's milk the casein varies between 3*3 and 6 per cent,, and the other albumins from 0*3 to 0'4 per cent. In diseased milk the casein may be as low as 0'2 per cent, and the other albumins as high as 10 per cent. ij. (a) 10 c.c. milk is diluted with 100 c.c. distilled water and well mixed; a copper solution made by dissolving 63-5 grams cupric sulphate in 1 litre of water is then added slowly with stirring until the coagulum begins to settle quickly. The whole mixture, together with half the cupric sulphate solution already employed, is then added to some potash solution (50 grams potash to the liti-e), and after a short interval the clear fluid is filtered off through a filter dried at 1 10° ; the precipitate is Avashcd until the washings amount to 250 c.c, and the sugar is to be estimated in this subsequently. (6) The coagxilum on the filter is next treated with absolute alcohol, slowly dried, and extracted with ether; the ethereal and alcoholic extracts are then to be distilled, and the fatty residue dried and weighed. The coagulum, after having been dried :it 125°, is weighed, then ignited, the ash deducted, and the difference taken as pure albuminoid (Ritthausen). 4. The Surjar. — (j) Take 25 grams of milk, acidify with hydro- chloric acid, boil, and filter, washing the coagulum with water; and to convert the milk sugar into glucose boil the filtrate and washings for an hour or so in a flask to the mouth of which a long tube has been attached. When the liquid cools make its volume up to 200 c.c, and determine the sugar by Fehling's method (p. 76), measuring 20ccFehling's solution into a flask, diluting with 80 c.c. water, and to the boiling mixture adding the diluted filtrate from a Mohr's 1)urette until the copper is entirely reduced. (ij) This sugar determination may be readily effected by the THE ANALYSIS OF MILK. 399 polariscope. Measure 40 c.c. milk into a flask of 100 c.c. capacity, add some carbonate of soda if the milk is not alkaline, and then 20 c.c. moderately concentrated solution of neutral acetate of lead, and shake well ; having next fitted tlie neck of the flask to a long glass tube or to the condenser of a Liebig's still, boil it over a small flame ; then filter and test the filtrate with the polariscope (p, 73). With a 1 -decimetre tube the percentage of sugar is obtained by multiplying the rotation by l'44r. 400 BOOK IV. EXCRETA: THE F.ECES AND UEINE. CHAPTER I. THE FJ<:CES. In the faeces are contained the undigested parts of the food swallowed, as well as the different excreta of the bile and in- testinal secretions ; and accordingly its composition will vary very much according to the nature of the diet. The colour of the faeces also varies, being due to the more or less altered biliary pigments, but depending largely on the nature of the food, having a dark brown colour with an exclusive meat diet, a yellowish brown with a mixed diet, and a yellow with a milk diet. In diarrhoea the faeces are generally light in colour, and in jaundice they may be quite colourless. The smell depends largely on the indol and skatol, and to a less degree on the valerianic and butyric acids and the sulphuretted hydrogen present. The reaction is neutral or alkaline, though occa- sionally acid, but it depends greatly on the character of the food : with an exclusively meat diet the acid reaction continues longer in the small intestine than with a vegetable diet (Bert). Aniovrnt. — In man the faeces form J-th to ^th of the fresh solid foods ingested, averaging about 5^ oz. ( Liebig) ; or the dried faeces with a nitrogenous diet, about -^i\\ to j\th of the food calculated in the dry state, but about ^th to |th with a bread diet (BiscHOFF and VoiT with dogs). The quicker the food passes through the intestine the greater is the absolute amount of faeces. Chemical Composition. I General Com,ponent.) ,S'/>//.>'. — C'liiclU' solul)lo salts of llic alkaline eaillis ; but in diarili(ca, itc, also silts of the alkalies. When the rea^tiuu is alkaline or nential triple phosphate is constantly present. (c) Portions of food (1) undigested, either from being in excess, as in the case of starches, fatty bodies, and crnde albumins ; (2) imjx'r- fectlij ditjrsted or absorbed, as fatty enudsions or fatty acids, leiicin, tyrosin, r(ad and animal diet (Ber- ZELILS). ^Vater 75-3 Tarts soluble in water . . . o'7 Bile 09 Albumin 0-9 Extractives 27 Halts 1-2 Insoluble constituents . . . 21-0 Undigested food . . . .70 Mucus, fat, &c liO II. Ditto (Weiisakg). Fluids .... . 08-3 to 82-6 Solids .... . 31-7 „ 17-4 Ether extractives tl-5 Alcoholic „ 15-6 Watery „ 200 D D 402 EXCRETA: THE F.ECES AND URINE. III. Liorganic ComtiUtents (Enderlin). Earthy phosphates . . 80-37 Silica . 7-94 Calcic sulphate . 4-53 Sodic phosphate . 2-63 Ferric „ ... . 209 Sodic chloride and sulphate . . 1-37 These vary from 16 to 57 grams (4 to 14^ drams) in the 24 hours. IV". Ultimate Percsntaje Composition loith a Meat and a Bread Diet. Meat diet Pieces Bread diet Faces c 51-95 43-49 4.5-41 47-39 H . 7-18 6-47 6-45 6-59 N 14-11 6-50 2-39 2-92 21-37 13-58 ! 41-63 3608 Salts . .5-39 30-01 1 4-12 7-02 V. The loss by the fajces in carbonic acid and nitrogen varies very considerably according to the food taken, thus (E,ubner) : — ■ Carbohy- drates in tlie food Loss per cent. of carbonic acid in the faxjes Niti-ogen in the food Loss per cent, of nitrogen in tlie fseces White bread Rice . Potatoes 891 to 670 493 718 1-4 to 0-8 0-9 7-6 Beef . Milk . White bread Rice . Potatoes 400 to 48-8 12-9 „ 25-8 7-7 „ 13-0 8-4 11-4 2-5 to 2-7 6-5 „ 120 18-7 „ 25-7 25-1 32-2 YI. Fermentation changes, some of which are fflosely allied to de- composition processes, undoubtedly occur in tlie intestine, as proved by the presence of free hydrogen ; we find even that chyme removed from the body, but maintained at the normal temperature, continues to evolve both carbonic acid gas and hydrogen. As will be seen by the following table, the nature of the diet affects the composition of the gases. (ffl) Small Intestine (PLANER). Bread diet Leguminous diet Per cent. Meat diet Per cent. Per cent. fO., . 38-8 47-3 401 N., . 51-2 4-0 45-5 H„ . iV?, 48-7 ]3i> 0, . 0-7 00 0-5 THE F.ECES. (J)) Large Intestine (Planer). 403 With meat diet Leginniiious diet Per cent. Per cent. CO, . 74-2 Gill H 14 21) H,S . . 0-8 N, . . 23fi 5-9 (Huge.) Milk diet Leguminous iliet Meat diet ' Per ceut. Per cent. Per cent. CO.. . I(v8 210 8-4 N., . 38-3 18-9 64-4 CH, . 0-9 55-9 26-4 H.. . 43-3 40 0-7 SHg . traces A small part of the carbonic acid, and possibly the chief part of the nitrogen, come from the swallowed aii-, the lest of the nitrogen being derived probably from the blood or from the splitting up of some of the proteids. Hydrogen is evolved in the butyric acid fermentation, and most likely also in some of the proteid decom- positions occurring in the intestine. Carburetted hydrogen has never been found in the intestinal gases of dogs or cats by Hofmann. The meconium, ov the contents of the intestine of the new-born child, forms a dark gieenish biown, or almost black, viscid mass, genei'ally with an acid reaction; it contains biliary acids more or less altered, bilirubin, biliverdin, cholesterin, and mucus; sulphates also are abundant, and calcic and magnesic phosphates, oxide of iron, and sodic chloride. White cells, generally green-stained, cylindiical epitlielial cells, intermixed with fatty drops and cholesterin crystals, are likewise to be seen under the microscojje. On analjjsis it yields about 20 to 27 per cent, solids, 1 per cent, ash, | per cent, fats, and ^ per cent, cholesterin (Z^yeifel). INDOL, CgHvN or CgH^^^CH.— This body belongs to the aromatic series, and is one of the products of the putrefaction of albumin. It is soluble in boiling water and easily soluble in alcohol and ether. Formed in the small intestine, it is in part excreted in the fjeceg, but part is absorbed and appears in an oxidised form in the urine as indoxylsulphuric acid or indican (C'sHyNSOj). Preparation. — Place in a large tiask 300 grams albumin with 4o litres of water ; add to this 300 grams finely divided ox pancreas, and digest the Avhole over a water bath at 40° to 45° for 70 hours 404 EXCRETA: THE F.ECES AND URINE. continuously. Then strain through linen, acidify with acetic acid, and distil in a tubulated retort over a sand bath to one-fourth the volume of the liquid. The filtered distillate is next to be rendered alkaline with liquor potassre and well shaken with its own volume of ether, and the ether decanted. On distilling the ethereal extract an oily substance remains behind, to which a little water is to be added; it is then boiled and allowed to crystallise. Properties. — It forms large, pearly, colouiless crystals, soluble in boiling water and in alcohol and ether. The dilute solution on the addition of chromic acid gives a voluminous, dark violet brown jirecipitate which is insoluble in ether, chloroform, and benzol, but easily soluble in hydrochloric acid, forming a violet solution. If to a solution of indol in benzol picric acid is added, needles of indol picrate are formed. Under the action of ozone a portion is converted into indigo blue. SKATOL is a constant constituent of the fteces (Brieger), and appears as a putrefaction product of albumin. It can he obtained by extracting fresh faeces with the third of its weight of water, acidifying with acetic acid (30 grams to each kilo, of fteces), and distilling off most of the added water. This distillate is heated with sodic carbonate and well shaken Avitb ether; the ethereal extract is evaporated and the residue boiled in some water. From the hot filtrate almost pure skatol crystallises out in delicate plates that have a well-marked ftecal odour. Treated with a drop of hot, fuming nitric acid, it gives no red precipitate like indol, but a whitish cloudy one ; and from its hydro- chloric acid solution it is thrown down by the addition of picric acid in the fr)rm of red needles. EXCRETIN, C.20H35O (Hinterberger), is a cholesterin-like body that exists in faeces in very small amount. It is prepared by exhausting fresh fseces with boiling alcohol (90 per cent.), filtering after a week, and pi-ecipitating the filtrate with milk of lime. The precipitate is dried and exhausted with a hot mixtvu'e of alcohol and ether ; the extract, after several days, deposits yellow crystalline needles of excretin, which can be purified by r<'Ciystallising them from alcohol (95 per cent.) Pathology. — Different abnormul constituents may be met with in the feces, chiefly abnormal, however, from being in excess. Alhuinin and mucus occur in the evacuations of cholera, typhoid fever, and dysentery, the mucus increasing particularly in catarrh of the intestinal tract and in hfcmonha'dc affections. THE FJX'ES. 405 Hill' may bo absent in jaundice, itc-., causing tlie fa'cos to have a light colour ; or it niay bo present in excess, an/»^///c (CooH^oOj) and hezoardic {(^\^i{^(}^-\-2\^.,0) acids, the latter lieing a tannin derivative, A concretion from a horse had this composition : — Per cent Triple phosphate . 900 Organic constituents . . :s-2 Silica rr2 Earthj- sails 42 Oxide cf iron 10 Sodic chloride . . 0-5 Sulphuric acid . . 0-5 Soda .... . 0-4 Lime .... 0-2 Pliosphoric acid 0-2 Scijhalie consist of masses of mucus mixed with excrement an9^gg.g^ 98-9 c.c. water must be added. The chief complication to which this process is subject is due to the presence of carbonic acid in the caustic soda, as this acid when evolved affects the indicator. Accordingly, to avoid this it is recommended to add at fii'st only as much soda as to render the solution coloui-less, then to boil so as to expel the carbonic acid, after which the titration is to be proceeded with in the usual way. 2. Determination of the Aciditij of Urine. — Take 100 c.c. of the urine and add to it from a graduated burette the normal soda solution (1 c.c. = 0063 oxalic acid\ which had best be diluted with water to one-tenth its strength (1 c.c. == 000G3 oxalic acid). From time to time, after stirring the fluid with a glass rod, narrow slips of I'ed litmus paper are introduced, and the addition of the caustic soda continued until the litmus paper begins to turn blue. Or violet litmus paper may be streaked with a thin glass rod moistened with the mixture, and the addition continued until no change of colour is produced. If, say, 13 c.c. of the diluted soda solution were required, then the acidity of the 100 c.c. urine is 13 x 00003 = 00819 ; and for the total urine of the 24 hours — say 1,.500 c.c. — the acidity expressed as oxalic acid is therefore equal to 1-2185 gi-am. The presence of the acid phosphate of soda in the urine, it should be remembered, renders the result merely approximative. B. Colour. — Normal urine possesses a clear amber yellow colour, that passed in the morning being generally daikest in tint. The colour deepens as the urine stands, and depends on the nature of the 410 EXCRETA: THE F.ECES AXD URINE. food, and in part oii the age and character of the individual. In very young children the tint is very slight, and the larger the quantity passed in adults the paler it becomes. It is pale in colour, as in the iirina pofus of health, in ansemia, chlorosis, and diabetes, and in the reconvalescence after severe acute affections. It is very rich in colour in acute fevers, just as is seen normally in the urina chyli of health and after profuse sweating with little ingestion of water. The presence of bile pigments imparts a brownish coloration accompanied by a greenish tint, that of blood or its pigments a reddish coloration ; in chyluria it is yellowish white, and in melanotic cancer greenish yellow, turning to a dark brown or black. Some- times the surface presents a blue colour, from the jiresence of indigo. Certain drugs and vegetables likewise aifect the colour ; thus the urine is blackish after phenol, dark also after gallic acid, brownish yellow after santonin, intensely yellow after chrysophanic acid, rhubarb (changed to red by ammonia), senna, logwood, madder, beet I'oot, and bilberries. The coloration by these vegetable pigments is changed to a blood red by alkalies, and the yellow tint restored by acids. To remove the colour of urine it may be filtered through animal charcoal, or j)recipitated with basic lead acetate or milk of lime, or digested with zinc and hydrochloric acid, C. Transparency. — Normal urine is always clear, but occasionally, and particularly in abnormal conditions, it is turbid. For the first four or five days after birth a child's urine is somewhat turbid, owing to epithelium, mucus corpuscles, urates, and occasionally oxalate of lime. Urine may be turbid when passed, and this indicates an excess of mucus, or the pi^esence of renal epithelium, pus, blood, chyle, semen, bile, or phosphate or urate of soda in excess, tfec. A turbidity shortly subsequent to the passage of the urine is generally the result of the precipitation of phosphates or urates, or it may result from fermentation or decomposition. But even normally a turbidity may show itself some hours after the urine has been passed. D. Quantity.— In the 24 hours 1,500 to 1,700 c.c. (about 521 to 59^ oz.), increasing with general functional activity and diminishing during .sleep. It may be increased to 2,000 or even 3,000 c.c. when much fluid has been ingested, or it may sink to 800 or 900 c.c. Women also secrete, as a rule, less than men. The amount depends considerably on the l>lood pressure in the kidneys. This, we know, is raised by increased force and frequency of the heart's beat, and by constriction of the vessels supplying other parts of the body, as the skin, particularly if accompanied Ijy a relaxation of the renal artery; THE URINE. 411 Avhile it is diminished by a lowering of the general blood pressure either from diminished cardiac activity or by a dilatation of other vascular nveiG of the body. Section of the spinal cord below the medulla leads to an arrest of the secretion by causing a general vascular dilatation ; in-itation of the spinal cord effects the same thing, but by causing a general con- striction of the vessels, the renal arteries included. Section of the renal nerves likewise leads to polyuria, also section of tin; splanchnics, but to a less extent, possibly through divi.sion of the vasomotor nerves of the kidney ; while stimulation of the splanchnics an-ests the flow (after Foster). Different names have been given to the urine voided at different times of the 24 hours. Thus urina j)otus is that passed after much fluid has been drunk, as in summer ; it is pale in colour and of low sp. gravity. The iirina cihi is that excreted soon aftei- a meal ; it is darker in coloxu' and of high sp. gravity. The uj-b/n saajnlnis is that formed during the night and voided in the morning. The quantity is affected by the food and fluids ingested, and b}' the secretive energy of the skin and lungs, being always increased after meals and nervous activity, and diminished by sleep. The influence of age is considerable. At the end of the first month the daily excretion of urine is about 200 to 300 c.c, and from three to five years a mean of 750 c.c. in boys and of 70(J c.c. in girls. While in the child (from three to seven years) the amount of m-ine in the 24 hours for each kilo. (2*2 lbs.) of body weight averages about 59 c.c, in middle age (30 to 60 yeai-s) a healthy adult drinking abund- antly of fluids only secretes about 24 c.c. per kilo. ; that is, the activity of the .secretion is about 2"5 times greater in the early period. Urine of Cldldrcn (ScHABANOWA). Age Quantity Sp.gr. 2 to 4 years . . 175 oz. 1011 5 » 9 ,, • . 3fv.5 „ 1013 .0 „ 13 „ . . .'50 „ 1012 In certain conditions the urine is greatly increased in amount, constituting iiolijuria,, which is present in diabetes insipidus and mellitus, in granular contracted kidney with cardiac hypertrophy, in the early stages of waxy kidney, and it may occur after the absorption of cedematous fluids or exudations, in the convalescence of fevers {epicritical jwlt/uria), and in certain disturbances and alterations of the nerve centres, as in cases of hysteria, chorea, epilepsy, &c. On the other liand it is diminished, or even occasionally absent [anttria. 41i> EXCTiETA: THE F.ECES AND TJlilNE. vli(/i(ria), iu cases of ^veakened heart action from degeneration, or in valvular disease leading to passive congestion of the kidney; iu emphysema, itc, of the lung in which the circulation is retarded; also in all acute indammatory processes, profuse sweating, &c., and cases wheie there is excessive discharge of water l)y the intestine, as in diarrhoea, enteritis, and cholera. Further, a diminution has been noted in the following : lead poisoning ; eclampsia parturientmm depending on spasm of the renal arteries (Cohnheim) ; mechanical compression or closure of the ureter ; filling up of the renal tubes with casts, itc, as in nephritis, a diminution being present in the last stage of all forms of Bright's disease; during the collapse of cholera, and in cirrhosis of the liver. It should be remembered that for accurate quantitative analyses the whole urine passed in the 24 hours must be preserved in the same vessel, and a specimen of this used ; for the amount passed, say in an hour, cannot be taken as a guide, as normally in one hour only 20 c.c. may be secreted, and in another hour as much as 200 c.c. Further, in noting the total quantity of urine in the day, the amount of fluids ingested should be recorded, as well as the presence of fluxes from the skin or bowels. E. Specific Gravity. — It is of more importance to ascertain the sp. gravity of the total urine passed in the 24 hours than of a portion of it passed at any one act of micturition. As the sp. gravity depends on the amount of solids present, a high sp, gi'avity indicates a large percentage of solids. Indeed, an ajjproximation to the solids present may be made by multiplying the last two numbers of the sp. gravity by 233. Thus a in-ine having a sp. gravity of 1018 would contain (18 X 2-33 --. 41-94) 41-94 grams of solids in the 1,000 parts. Fairly accurate results will be obtained by substitutiiig • 2 for 2 33, as, besides being easier to use and rememljcr, it is a mean of the different numl)ei\s that have been proposed fur the purpose. I3ut thci-e are cases where the i-esults thus obtained aie very erroneous, and accord- ingly if a correct estimate is required tlie solids obtained by evapo- rating a certain volume of the urine should be weighed. Variations. — Copious ingestion of fluid lowers it greatly, and much vomiting and purging may not only lessen the amount of urine but, also its sp. gravity. After attacks of hysteria it may be temporarily as low as 1003. A low sp. gravity geneially indicates a deficiency in the excretion of tlie waste jn-oducts, as in hydriemia, anwmia, und chloiosis; albuminous urine also is generally of low sp. gravity, 1010 to 1012. A child of a month old has a urine with a .'sp. gravity often as low as 1003. At birth it is about 1010; then THE URINE 413 1000 1005 1010 1015 1020 1025 1030 1035 1C40 ^104 5 it sinks, so tli;it al)Out the teiitli day it may be 1002, wlion it gradually begins to rise again. With the same individual also the proportion oF solids may vary normally as niucli as one-third more or less from day to day. The sp. gravity is generally raised when the urinary secretion is lessened, as in fevers, but the contrary is the case in polyuria. In most chronic diseases the solids are diminished and the sjjcciiic gravity lowered. In the acme of acute in- flammatory processes, while the total solids may be only 40 grams in the 24 hours, yet, on account of the les- sened excretion of water, the sj). gravity is higher than normal. It is also raised in the scanty urine of acute renal dropsy. An increased sp. gravity with an increased excretion of urine should be regarded Avith sus- picion, being generally associated with diabete?, in which disease it is often as high as 1040 to lOoO. With ex- cess of urea it may rise to 1030 or even higher. Little ttrine ivith in- creased sp. (jravitu indicates diminished secretion, other watery effusions, or the presence of some morbid process ; much urine ivith a lovj s]^. gravity/, abundant ingestion of water or absoi'p- tion of exudations or effusions, also some forms of diseased kidney ; little urine with a loio sjj. gravity, ui'femia and some forms of Bright's disease, particularly in the later stages; and quantity much increased ivith a liigh sj). gravity, diabetes. To Take the Specific Gravity. — This is usually done by means of the urinometer. The urine is poured into a long, narrow, cylindrical glass and the urinometer inserted. The latter should be made to sink slowly into the urine, and when it has come to rest read off at the level of the fluid. The cylinder must be sufficiently wide to permit of the urinometer floating freely without touching ; and before f -UUI.XUJlETh.lt. 414 EXCBETA: THE FECES AM) URINE. the urinonielor is inserted it should be carefully dried if necessav}', and if any particles of air adhere to it while in the urine, these aie to be wiped away with a feather ; any froth also on the surface of the urine is to be previously removed Avith a slip of filter paper. The temperature of the urine should be about 15°, as the urinometer is jjenerally constructed to give accurate indic;\tions at this temperature : if below this point the sp. gravity obtained is too high by about 0*1° for each degree down to 7° ; and too low, above 15°, by an average of 0-1° for each degree up to 18°, and from that to 25° by an average of 02° for each degree. If the lU'ine is in too small quantity to admit the use of the lu-inometer, sp. gravity beads or bottles may be employed. To obtain accuratdij the amount of solids is a difficult operation, owing to the hygroscopic character of the residue and to the de- composition of the urea piesent in it when sufficiently heated to expel all the moisture. One of the following plans may be adopted : (1) Evaporate 5 c.c. in a small weighed ])latinum capsule over a water bath, and weigh the residue after it has been dried for some time in an air bath at 115° and then cooled over sulphuric acid. Only a roughly approximative estimate is thus obtained. (2) Remove 5 c.c. of the urine with a pipette, and evaporate it in the receiver of an air pump in a weighed capsule placed over a dish, containing strong sulphuiic acid. Leave for 24 hours in vacuo, then weigh; and the weighing may be repeated after another 24 hours over fresh sulphuric acid in the exhausted receiver. (3) To obtain the ash 50 c.c. urino are evaporated to dryness in a weighed })latinum crucible over a water bath, and then carefully heated in the flame of a Bunsen burner. Add a little water to the capsule when cool, then warm it and throw the contents upon a small filter that has been previously treated with hydiochloric acid and A\ell washed; repeat the washing of the capsule, filter, and collect the filtrate and washings. The filter and its contents are next to be heated to dryness, and the dry filter expo.sed to a red heat in a platinum capsule. The ash will soon te reduced to whiteness, as the alkali salts, which hinder tlic burning of the carbon, have l)een re- moved by the washing. The filtrate and the washings are now to bo added to the same capsule and to be evaporated to dryness ; the diy residue is finally heated to redness, alloAved to cool in an exhausted receiver over sulphuric acid, and weighed. The ratio of the mineral to the organic residue varies somewhat, but in hialthy urine it is generally in the proportion of 1 to 1-2 or 1-7, while in abnormal urine the ratio may be 1 to 2, 2*5, or 4; that is, there i.s a higher j)roportion of organic matter (Wanklyn). THE URINE. 415 F. Odour. — Fresh urine has a faintly aromatic smell, which soon, however, disappears; it hecomes ammoniacal when the urine docoin- poses. Its characteristic odour may be altered by the ingestion of certain foods, as hare, asparagus, garlic, turpentine, saffron, balsam copaiba, cubebs, assafcetida, valerian, etc. CHAPTER III. CONSTITUENTS OF URINE. The secretion of urine is a double process, partly filtration and partly excretion, this last being less dependent than the former upon alterations in the blood pressure. By filtration, which occurs chiefly in the Malpighian capsules of the kidney, the bulk of the water and of certain soluble bodies are eliminated ; and by excretion the great proportion of the solids with only a small part of the water in the tubules by means of their epi- thelial investment, this last process being greatly dependent on the stimulating presence of certain bodies in the blood, such as urea, &c. The urine is the chief means by which the decomposition products of the albumins are excreted. The members of the aromatic series present in it can all be traced back to this source. The sulphur of the albumin is probably in part oxidised, and gives origin to some of the combined sulphuric acid of the urine. Traces also of the decomposition products of the lecithin, nuclein, and glycerin phosphoric acid of the nerve substance show themselves : probably part of the phosphoric acid of the urine is thus derived. In addition there are traces of the decomposition products of the carbohydrates and of sugar itself. Elsewhere reference will be made in more detail to the origin of the different minary constituents, and it will be seen that the true function of the kidneys is chiefly excretory — that is, they are mainly occupied in discharging from the blood certain waste products that have been carried to them from other tissues or organs. These bodies may be classified into — A. Organic. — 1. Bodies belonging to the fatty series — 416 EXCRETA : THE F.-ECES AXD URIXE. urea, urio acid, xanthin, bypoxaiithin, kreatin and kreatinin ; oxalic, oxaliuic, glycerophosphoric, and lactic acids. 2. Bodies belonrjing to the aromatic series — hippuric, ben- zoic, phenolsulplmric, indoxylsulphuric, and skatolsulphuric - acids. o. Such bodies as urobilin, extractives, and organic bodies containing sulphur, &c. B Inorganic. — Sodium chloride, alkaline sulphates and phosphates, phosphates of lime and magnesia, silicic acid, ammonia, iron, nitric acid, and such gases as carbonic anhydride, nitrogen, and oxygen. Of these the important constituents are urea and sodinra chloride, which normally bear to each other the proportion of "2 to 1, but in febrile conditions may be altered to 30 to 1. Normal Urine of the 21 Hours (after LlEBBRMAXs). Constituents Water Sp. gravity Urea Uric acid Kreatinin . Hippuric acid Snlphuric „ Amount in grains 52 OZ. Alterations under pathological conditions 1U20 100 to 600 12 10 „ 18 %\ „ :3S Increased in diabetes, after absorption of effusions, and in contracted kidney, &c. DiininisJied in acute fevers, cliolera, drop- sies, &c. Baiscd in diabetes mellitus, and occasion- ally in diabetes insipidus. Lowered in polyuria and certain cachectic conditions depending on want of food, &c. Increased in fevers to the crisis, in inter- mirtent fever before the cold stage, in diabetes, and after absorption of drop- sical effusions. Diminished in dropsies, in chronic liver diseases, in Briglit's disease, after fevers, and in all conditions in which tissue change is hindered. Increased, in acute fevers, in diseases of the lungs interfering with respiration (as i\ibercular deposit, &c.), acute rlieunia- tism, Icukrcmia. Diminished in diabetes, chronic gout, Addison's disea,se. Increased in acute fevers, pneumonia, &c. Diminished in diabetes mellitus, debility, kidney disease, &c. Increased in fevers, diabetes mellitus, and chorea. Having more or less the same source as urea, it will increase or diminish there- with. CONSTITUENTS OF URINE. 417 Xnrmnl Urine of the 2\ Hours — continued. Amount in Constituents grains Alterations under patliological conditions Phosphoric acid 48 to 54 Increased in fevers, in most acute nerve affections, and in tubercle of the lung. Diminislu-d in many mental diseases, es- pecially mania, and in chlorosis. | Oxalic „ . 0-3 Increased in catarrlial jaundice and in oxalic acid diathesis. Carbolic „ . 0-015 Increased in certain diseases of the intes- tines, causing constipation (ileus, &c.) ; but has been observed to be increased also in certain cases of diarrhcea. Phosphate of 4 to 5 Increased in o.steomalacia, rickets, scrofula, lime carcinoma, long-continued suppuration. Diinbiished in fevers. Phosphate of Magnesium . 7 „ 11 Cliloride of 150 „ 200 Increased in fevers at the outset, and with Sodium fCl = 90 to the reabsorption of dropsical fluids. J 120 Diminished during apyrexia, dropsies, j Na = 60 to cholera, typhus, inflammations generally, I 80 and especially pneumonia. Free acid (cal- 30 to 60 Increased during the acme of acute febrile culated as ox- affections (on account probably of the alic acid) diminished proportion of water present). Diminished in most diseases ailecting the nutrition and leading to a deficiency therein. Indican . 0-07 „ 0-3 Increased with diseases attended by con- stipation, and occasionally also in cases of diarrhoea. Total inorganic salts 200 „ 380 Potassium . B8 „ 48 Sodium 140 „ 180 Calcium 4 „ 5 Magnesium 2 „ 3 The Gases in Urine. — These amount on an average to 15*79 per cent., of which carbonic acid forms 8 7 "5 3 per cent., nitrogen 11*22 per cent., and oxygen 0*62 percent. (Planer). Accord- ing to Pfluger the proportions are the following at 0° and 760 mm. :— Per cent. Carbonic acid, by exhaustion in racno . . \lo to 18'8 „ „ action of phosphoric acid in vacuo 019 „ 0-9 Oxygen 009 „ 010 Nitrogen 115 „ 121 The carbonic acid appears to exist chiefly in a loose state of combination, probably with sodic phosphate. £ £ 418 EXCRETA: THE FJECES AND URINE. Amount of Solids. — Of these the urine therefore contains nearly 42 grams (648 grs.) in each litre ; but they may vary from 20 to 65 grams (300 to 1,000 grs.) In the twenty-four hours the solids average ^6 to 60 grams (840 to 920 grs.) Mean quantity in 1 kilo. (2-2 lbs.) Mean quantity in 24 hours Water Organic constituents Mineral „ Grams 9560 27-18 160 Grains 14.753 419-4 247 Grams 1,243 35-24 20-2 Grains 19,182 644 312 In general the solids increase with the quantity of urine excreted. In all grave diseases the solids diminish in the twenty-four hours, but as the urine is also generally passed in less quantity the proportion remains nearly the same. In acute maladies the volume of urine decreases, but the sp. gi-avity increases ; and as the patient improves its volume rises, and may even pass the normal considerably. In diabetes not only is the volume of the urine but also the solids greatly increased, while in certain states of the system, as hydrsemia, chlorosis, ansemia, hysteria, &c., we may often meet with simple polyuria. CHAPTER IV. REACTIONS AND CHARACTERISTICS OF NORMAL URINE. 1. Acid Reaction. — Dip into the urine a piece of blue litmus paper : it becomes red. 2. Density. — Pour some into a cylindrical glass and insert a urinometer: the sp. gravity should be about 1020 ; if higher than 1025, sugar or excess of urea may be present. 3. Uric Acid and Plfjment. — (a) Add a little hydrochloric or nitric acid: no preci})itate occurs, but the urine evolves a characteristic odour and becomes dark-coloured. (6) When the urine is carefully jtoured over some nitric acid in a test ghiss, at the pf)int of contact of tlie two fluids a reddish layer forms (HELLEii's uropluein ring), and a little above this last often a whitish layer of urates, sharply defined below but less so above. CHARACTERISTICS OF NORMAL URINE. 419 (c) If we add to hydrochloric acid one-third its volume of urine the mixture assumes a pale red, brownish red, or a violet to a deep blue coloration (indican, &c.) {d) Pour some strong sulphuric acid into a beaker, then about twice its volume of urine, and mix rapidly with a glass rod : a more or less dark brown colour is developed. In certain chronic liver affections the colour may be quite black. (e) Saturated solution of picric acid causes no alteration of colour, but the urine remains clear for three or four hours, when a slight yellow-coloured sediment ajipears. 4. Boil a little in a test tube : the urine remains clear, its acid reaction unaltered ; but if it is neutral or alkaline a pre- cipitate of earthy phosphates will occur, which disappears on the addition of a few drops of nitric acid. If the urine is not transparent, but becomes so on boiling, excess of urates is present. 5. Phosphates of the Alkalies and of the Alkaline Earths. — (rt) Add a few drops nitric acid to the urine and boil, then add a little barium chloride solution and boil again for some time: baric sulphate is precipitated. Now filter rapidly and treat the filtrate with excess of ammonia, when haric phosphate is thrown down. (j) Confirm the presence of the alkaline phosphate by boil- ing some nitric acid solution of ammonium molyhdate in a test tube, and then adding to it a little urine, when a canary yellow precipitate of ammonium phosphomolybdate is thrown down. (ij) To a fresh portion of mine add sodic acetate and then acetic acid and a drop of ferric chloride : a yellowish white gela- tinous precipitate is thrown down of ferric phosphate. (6) Add ammonium chloride and ammonia in excess : a white preci})itate of the eaythy phosphates (lime and magnesia) and of oxalate of lime. Filter and add to the filtrate a little solution of magnesia sulphate, and a j)recipitate of the alka- line phosphates occurs as triple ploosphates. (Or the next method may be adopted.) (c) Add to the urine acetate of ammonia (prepared by adding acetic acid to liquor ammonise till the acid is in excess), and to complete the precipitation add oxalate of ammonia : a 420 EXCRETA: THE F.ECES AND URINE. little oxalate of lime is thrown clown. Now boil, filter, and to the filtrate add excess of ammonia, shaking or stirring briskly : a crystalline precipitate of the triple jjhosjpltate. The tests under this head having first been applied to the urine itself should next be gone through luitha solution of the di'y residue. To effect this evaporate about 20 grams of urine to dryness, and incinerate the residue. Then boil this last with a little water and filter: the filtrate will contain the phosphates of the alkalies, and the insoluble residue the earthy phosphates. (j) To the filtrate apply test a; then try test 6, when it will be found that no precipitate is obtained. Next add to a little of the filtrate ammonium chloride, ammonia, and magnesic sulphate, when a precipitate of the triple phosphate will be obtained. (ij) The part of the calcined residue insoluble in water is then to be dissolved in a few drops of nitric acid, a little water added, and the solution filtered (the insoluble residue generally consists of silica). To part of the clear solution add excess of ammonia : pjhospjhate of Urine and ammoniaco-magnesian pjhospjhate are precipitated. To the rest of the solution add ammonia and then excess of acetic acid and oxalate of ammonia : oxalate of lime is thrown down. Shake well, boil, and filter; concentrate the filtrate by evaporation, and when it is cold add ammonium chloride and sodic phosphate, stining well : a crystalline deposit of the trijjle jjhosphate. 6. Soluble Salphates. — Add baric chloride or baric hydrate or nitrate : a white precipitate of baric sulphate, phosphate and urate, which disappears in part on the addition of hydro- chloric acid, the sulphoAe only being insoluble and remaining as a finely pulverulent mass. 7. Urea. — (a,) The phosphates must first be separated before applying the following test ; accordingly add to the urine barium chloride in excess, and filter off the precipitate ; now add to the clear filtrate some dilute solution of mercuric nitrate, and a white flocculent precipitate consisting of a com- bination of urea and mercuric nitrate is obtained. {}}) Evaporate some urine over a water bath to a syrupy con- CHARACTERISTICS OF NORMAL URINE. 421 sistence ; place a little of this syrup in a watch glass with an equal volume of pure nitric acid, and float the watch glass on cold water : a crystalline mass of nitrate of urea will soon form. Digest the rest of the syrup with spirit, and then evaporate the extract obtained ; dissolve up the residue in a little water, and place a few drops on two microscopic slides ; insert a fine thread in the fluid on each slide, and then apply cover glasses, leaving part of the thread uncovered. To the outer part of one thread apply a drop of nitric acid, and a drop of strong oxalic acid solution to the other thread, and note the formation of crystals under the microscope. 8. Precipitates luith Lead. — Add some solution of acetate of lead : a thick precipitate falls, consisting of chloride, plios- l)hate, urate, and sulphate of lead, as also most of the pigment present. Filter and note the clearness of the filtrate. 9. Chlorides. — Add silver nitrate : a white precipitate of chloride and phosphate of silver ; add a few drops of nitric acid, and the phosphate dissolves ; filter and note that the silver chloride forms a white, cheesy mass that is soluble in ammonia and becomes darker on exposure to the light. 10. Salts of Lime, Magnesia, and Ammonia. — {a) Add a little sodic acetate in excess and then oxalate of ammonia : a slight white precipitate of oxalate of lime, which becomes more evident on boiling and is insoluble in acetic acid. Now filter and add ammonia to the filtrate, when the magnesia will be thrown down as ammonio-magnesian phosphate. (6) To 50 c.c. of urine add some milk of lime, then boil in a small flask and test the vapours given off with a glass rod that has been dipped in hydrochloric acid, when white fumes will be formed if ammonia is present ; note the smell also, and test the reaction of the vapour with a piece of red litmus paper : ammonia will be indicated by its pungent odoiu- and by the blue coloration of the litmus, 11. Hijjptiric Acid.— It is advisable to use cow's urine for this experiment. Boil it for some time to remove excess of pig- ment, and filter ; evaporate rapidly to a syrnp, allow it to cool, and then acidulate with hydrochloric acid ; lay aside, and after 24 hours decant from the deposited crystals. These are gene- 422 EXCRETA: THE FMCES AND URINE. rally much coloured from admixture with pigment. Place some of the dry crystals in a small reduction tube and heat, when a sublimation will occur of benzoic acid, an odour of fresh hay or nitrobenzol being evolved and oily red drops formed. Also examine the crystals under the microscope ; they generally form fine needles. 12. Kreatinin. — To 100 c.c. urine add some milk of, lime, and then some solution of chloride of lime to complete preci- pitation ; tilter after some time and evaporate the filtrate to a syrup ; add to this about 30 c.c. absolute alcohol, and after mixing well lay aside for 5 hours or so in a small beaker ; then add 10 to 15 drops of alcoholic solution of chloride of zinc, and lay aside again : a precipitate of kreatinin chloride of zinc occurs by degrees. Examine the deposit under the microscope, and note the prismatic crystals or fine needles arranged in rosettes or bundles. . 13. Normal urine decolourises a weak amvioniacal cupric oxide solution. Tannin gives no precipitate with it. The addition to urine of three times its volume of alcohol (90 per cent.) causes a precipitate due chiefly to earthy phosphates. If this precipitate is dissolved in water a solution is obtained which can change starch into sugar (Bi^champ's nephro- zymase). CHAPTER V. UREA. The formula for this body is CONgH^ = CO j™^. its mole- cular weight is 60, and it contains 46*6 per cent, nitrogen. It is found in small proportion in the different animal fluids, tissues, and organs, being absent, however, from muscle, but especially rich in theliver (0*20 toO*4Gper cent.), although this last is denied by Hoppe Seyler. In hnman blood there is present 0-142 to 0-177 per cent., though" it may be as low as 0-02 per cent. ; but in Pjright's disease it has been found as high as 1-5 per cent. In the blood of the dog the proportion is 0-0192 ]jer cent. (Wurtz), or 0*014 to 0-085 per cent. UltEA. 423 (PEKFXiiARiNCx), Urea is the principal element of the urine, this fluid containing 2 to 4 per cent., or an average mean of 2-5 to 3-2 per cent. Preparation. 1. From Urine— {n) Evaporate the filtered urine to a syriijiy consistence, then allow it to cool, and it is advisable to suiTOund the vessel containing it with a freezing mixture ; next add colourless nitric acid in excess, or in about the same volume as the concentrated urine, and lay aside for 24 hours. Decant and collect the precipitate on a linen filter; spread it out from this upon a porous earthenware plate, and after some time dissolve it in hot water. If it is much coloured shake the solution for some minutes with animal charcoal and filter. To the filtrate add baric carbonate to neutralisation, then a little caustic baryta, and pass a current of carbonic acid gas through the fluid for a few minutes [2(CON2H4.HN03) + BaCOg = 2CON"oH4+ Ba2N03 + H20 + C02]. Filter again, evaporate the filtrate, and having dried the impure urea thus obtained by spreading it out between sheets of filter paper, boil it in absolute alcohol, filter, and from the filtrate allow the urea to crystallise out. (A) The urine, particularly that of the dog, may be thus treated : Add 1 vol. baryta mixture [saturated solution of baric hydrate (2) and of baric nitrate (1)] to 2 vols, of the urine, shake together, and filter ; evaporate the filtrate to dryness, and treat the residue with boiling alcohol ; filter the alcoholic solution, and from the filtrate the urea is allowed to separate. If not transparent it is dissolved vp again and filtered through animal charcoal, and the clear solution finally evaporated. 2. Artificial Preparation. — Powder some potassic ferrocyanide, dry it over a water bath, and I'ub 100 grams of it well together witli 50 grams black manganic oxide ; then heat the mixture to redness on an ii-on plate. Before it has quite cooled break the mass up in a mortar and shake it well with a warm solution of 50 grams sulphate of ammonia, heat for a few minutes, filter, and evaporate the filtrate to dryness. The urea present is separated from the alkaline sulphates mixed with it by warming the residue with a small quantity of absolute alcohol (90 per cent.) The alcoholic extract is distilled, and the urea left behind is recry stall ised from boiling absolute alcohol. General Characters. — Urea in the pure state forms long flattened fom'-sided prisms that are striated, translucent, and silky, and terminated by oblique surfaces. Eapidly formed 434 EXCRETA: THE FMCES AND URINE. m pure a higher crystals are generally in the form of long, fine, white, glittering needles. These crystals dissolve readily in cold ■water and alcohol, being about twice as soluble in these fluids when boiling, but are almost insoluble ether. Urea melts at 130° and decomposes at temperature. Chemical Relations. — Urea is isomeric with ammonium cyanate (NH^CNO), this body undergoing spontaneous con- version into it, and it may therefore be readily prepared there- from. In the transformation energy is evolved, so that the cyanate with its molecular energy may be regarded as a type of vitally active nitrogen, and the urea as that of dead nitrogen (Pfluger). Urea is generally considered to be an amide of carbonic anhydride : OC -' -.tj carbonic acid; OC- ^tt^ carbamic acid ; OC 1 TVTTT^ carbamide. (NH, Combinations. — Behaving in some respects like an organic base, urea combines with acids, bases, and salts. The nitrate, CON,H4,HN03, is formed if nitric acid is added to a moderately concentrated solution of urea, generally appearing as very thin rhomboid al or hexagonal tables, although from some urines (as occasionally in Bright's disease, &c.) it may show itself in tufts of fine needles. The crystals are in water, less soluble in and insoluble in ether and nitric acid. The oxalate, (CON2H4)2C2H204 + H20, is also readily formed by the addition of a strong solution of the acid to a moderately concentrated solution of urea. The crystals form rhomboidal tables or long thin prisms, and are very variable in shape. They are slightly soluble in water, and less so in alcohol. Nitrate of 'mercury combines with urea, and according to the concent lation of the solutions three combinations may be formed (LiEiU(i) — Vie. 29.— NiTHATE OF Urea Crystai-s. Crystals of nitrate of ur'>a— rliombic tables SOluble 071(1 pix-siiled plates (furnicd in plow crj-s- i i i tallisation). alcohoi, TJREA. 425 (l)(C0N,Hj,.Hg-,(N03).,; (2) (CON,H,),.Hg3(N()3),; (3) (CON,H,),.Hgrm)3), + 3HgO. The last is produced when a dilute solution of the nitrate is added to a dilute (about 2 per cent.) urea solution. Mercuric chloride gives a white gelatinous precipitate with an alkaline solution of urea. Sodimii chloride also combines with urea, CON2H4,NaCl + 2H20, forming brilliant rhombic prisms when a solution of the two bodies is evaporated. From such a solu- tion the urea is not completely precipitated by nitric acid. Compound ureas are formed when the hydrogen atoms of urea are re})laced by alcoholic or acid radicles ; as, CNOH (cyanic acid) + NH3(C2H,) (ethylamin) = C0.NH„.NH(C2H,) (ethyl urea); CNOH (cyanic acid) + NH(C2Hg)2 (diethylamin) = (CO.NH2N(aH,)2 (diethyl urea) ; CON^H, + C.HgO.Cl (acetyl chloride ) = CONH2.NHC2H30 (acetyl urea) + HCl. Decompositions. — Urea decomposes readily under the in- fluence of strong alkalies and acids, organic ferments, bacteria, &c., and even by the simple heating of watery solutions — slowly at boiling point, but rapidly if heated in a closed tube to 230°, or under pressure at 100° if mixed with baryta water — the elements of water being taken up and ammonium carbonate formed : — ^^JNH2 + -^2^^-^^(ONH, Nitrous acid, chlorine gas, and hypochlorite and hypo- bromite of soda decompose urea with the formation of carbonic acid, water, and nitrogen : — ^^-^{nh! + ^A-C02 + 2H20 + 2N2 C0J^^2 + H,0 + 3Cl2=C0,H-N2 + 6HCl ^^ Inh' + ^^^'^^^ = CO2 + ^2 H- 2H2O + 3NaBr. The nitrous acid reaction can easily be shown by adding a few drops of nitric acid to a globule of mercury in a test tube, when pungent red fumes of nitrous acid are evolved ; but if now a little urea is added only a colourless gas will be given off. If dry chlorine gas is passed over melted urea the latter 426 EXCRETA: THE FALCES AND URINE. is decomposed into cyanuric acid and nitrogen, hydrocliloric acid and ammonium chloride also bein^ formed : — 3C0|^j[j2^. 3CI2 = C3N3H3O3 (cyanuric aeid)+ N^ + 5HC1 + NH,C1. When heated with a mixture of caustic potash and potassic permanganate it is decomposed into carbonic acid and am- monia. If the ammonia is distilled off it can be determined in the distillate by Nessler'S process, and the amount of urea thus estimated. Potassic permanganate oxidises urea in acid, but not in alkaline solutions, while the inverse holds good with ozone. Derivatives. — When melted with sarcosin urea builds up TVHPO methyl hydantoin, CO^^//-,^ xprr , which is closely related to kreatin ; and when melted with leucin, uramido-caproic acid is formed. Other derivatives are biuret (C202N3Hg + H20), which is obtained by heating dry urea up to 150° and extract- ing the cooled mass with cold water; cvanamid (0H2N„) and guanidin (CN3H,). Urea Reactions and Tests. — Make a strong watery solution of urea, and perform most of the following tests with drops placed on microscope slides : — 1. Allow a drop to evaporate ; when nearly dry place a cover glass upon it, and examine under the microscope : note the white silky needles formed by the crystals, generally in the form of four-sided prisms terminated by oblique facets, or as delicate six-sided superimposed plates. 2. Place a short length of thread in a drop of the solution, then cover so as to leave part of the thread outside the cover glass ; now moisten the outer part of the thread with a drop of nitric acid, and under the microscope note the formation of crystals on each side of the thread, hexagonal tables or six- sided prisms being ultimately formed, the character of the crystals, however, being affected by their more or less rapid formation, &c. 3. Note in the same way the formation of crystals of oxalate of urea, re])lacing the nitric acid by a strong solution of oxalic acid. 4. Note the white ])ieeipitate with solution of 'mercuric UREA. 427 nitrate, and the absence of any precipitate when rnercuric chloride is added to an acid solution. 5. Place a few drops of a solution of sodic carbonate or bicarbonate in a test tube, then add a little mercuric nitrate, and a yellow precipitate is formed of mercuric hydrate. Now to another test tube add a little solution of lu'ea and some carbonate of soda ; then pour in a few drops of the mer- curic nitrate, and the white curdy precipitate is produced, owing to the urea, but no yellow colour at first ; after adding a little more of the nitrate, however, a yellow colour appears. So long, therefore, as there is urea jjreseiit to combine luiththe mercuric nitrate no yelloiv colour appears, this occurring only with excess of the mercuric salt. 6. Cover a large crystal of urea with a drop of a saturated watery solution oi furf urol (C4H3C).COH) and immediately add a drop of hydrochloric acid (sp. gr. I'l) : a rapid play of colours occurs from yellow, through green to purple violet, sometimes passing into brownish black. 7. Pour a few drops into a small test tube and add a little hypohromite of soda : the urea at once decomposes, bubbles of gas being given off. Use hypochlorite instead of hypobromite, and it will be seen that the decomposition does not occur readily till the mixture is heated. The process is seen best by using a small test tube which is nearly filled with the hypo- chlorite solution, then a little urea added, and the test tube rapidly inverted over water or mercury : the nitrogen evolved collects in the tube, the carbonic anhydride being absorbed. 8. Substitute nitrous acid for the hypobromite, and pro- ceed as in the last experiment : the urea is decomposed as before and gas evolved. 9. To separate the urea from urine for examination, evaporate about 15 c.c. in a water bath to a syrupy consistence, and digest this with an equal volume of alcohol. The alcoholic extract is then evaporated, and to the watery solution of the residue tests 2 and 3 are applied. If the urine is albuminous it is better first to separate the albumin by boiling and filter- ing after the addition of a few drops of acetic acid. If an excess of urea is present, in which case the specific gi-avity is generally high, mix equal volumes of the urine and of pure nitric 428 EXCRETA: THE FMCES AND URINE. acid in a watch glass, which is to be floated in cold water, and nitrate of urea soon appears. If an excess of urea is not present an equal volume of pure nitric acid may be added to the condensed urine, when the latter will soon become semisolid from the formation of nitrate of urea. 1 0. Detection of Urea in the Blood, &c, — The fresh-drawn blood or the serum of coagulated blood is mixed with four times its volume of alcohol, by which the albumins are precipi- tated. Filter, evaporate the filtrate to dryness, and exhaust the residue with absolute alcohol ; evaporate this in turn, and dissolve the residue in water. Add to the watery solution some baric hydrate to precipitate any phosphates present, filter, and pass a current of carbonic anhydride through the filtrate to separate any baryta, filter, and evaporate to a syrupy consistence. Divide this syrup into three parts ; add a drop of nitric acid to the first, of strong oxalic acid solution to the second, and test the third with mercuric nitrate. Then examine the first and second with the naked eye and under the microscope, and note any appearance of crystallisation. If the crystals are sup- posed to be compounds of urea, it is well to compare them with some freshly formed crystals of the nitrate and oxalate, so as to avoid the mistake of confounding them with the crystals that frequently form of alkaline nitrates, especially in presence of ex- tractives. Incinerate also : there is a residue with the alkaline salts, none with those of urea. CHAPTER VI. SOURCES AND AMOUNT, AND INFLUENCES AFFECTING THE LATTER. Source and Seat of Urea Formation. — The urea is most probably derived from the decomposition of albuminous bodies ; the amount of it excreted in the urine may therefore be taken as indicating tlie amount of albumin decomposition occurring in the body. According to Pakkes 9"/ per cent, of the nitrogen of the food is thus eliminated by the kidneys. P.kcmamp, many years ago, described the formation of urea from albumin SOURCES AND AMOUNT OF UREA. 429 through direct oxidation by the action of potassic permanganate in alkaline solutions, and although his statements have not been fully confirmed, he still maintains the accuracy of his former view ; and in this he has been supported by Ritter, who obtained in the same way 0"3 per cent, from white of egg, 0'33 per cent, from fibrin, and 0*7 per cent, from gluten. It has long been established (Prevost and Dumas) that after extirpation of the kidneys urea does not cease to be formed, but accumulates in the blood and tissues ; and modern opinion is in favour of the view that instead of being formed in the kidneys it takes its origin in the blood and in the different organs of the body, particularly the liver and spleen. But it is possible that the kidneys, besides merely excreting the already formed m-ea, may also assist in transforming some of its direct antecedents into urea. There is evidence of a continual formation of kreatin in different parts of the body, as in nervous tissues, muscles, spleen, &c., and it is probable that this kreatin is an antecedent of urea. Urea, although present in the blood, is not generally to be found in the parts just referred to as seats of kreatin formation. The urea is always increased by a diet rich in proteids. In this ease it is probable that an abundant formation of leucin and tyrosin takes place in the intestine, owing to a breaking down of peptones, and by their absorption and further decom- position in the liver (of the leucin at any rate) urea may be formed. In the liver much urea has been found (Meissner), and probably many of the metabolic processes resulting in the formation of urea here find a centre of activity. Schultzen is of opinion that in the normal metabolism of the proteids carbamic acid (CO.NH2.OH) and ammonia are the ultimate products, and that these by their subsequent dehydration form urea, C02N,Hg or CON^H^.H.jO (ammonium carbamate) — HgO = C0N2H^. It is thought probable, however, by others that all the nitrogen of urea comes to it in the form of ammonia, and that this is directly united to carbonic acid instead of carbamic acid, and subsequently dehydrated (Salkowski). When an animal is fasting the tissue waste supplies the urea. Thus lOOgi'ams of muscle substance contain about 3"4 430 EXCRETA: THE F.ECES AND URINE. grams of nitrogen, corresponding to 7*286 grams of urea ; every gram of urea accordingly represents 13*72 grams of muscle substance, and in a fasting animal, when a day or two have elapsed, every gram of urea in the urine is equivalent to 13*72 grams of muscle waste. After fasting about four days a dog weighing 20 kilos, excretes about 9 to 12 grams urea. 12 grams X 13*72 = 164*6 muscle — that is, about 165 grams of daily muscle waste. If now we give to the dog about 165 grams of flesh daily, as a result the loss of weight will cease, but the excretion of urea is increased : 12 4-9 = 21 gi-ams is about the amount of urea discharged, showing the urea due to tissue waste to be equal only to | of the amount previously derived from that source. If the food is doubled, and say 165 grams X 2 = 330 grams of flesh given, the excretion is 12x2 + 6 = 30 grams, indicating a decrease in the tissue waste. But this holds good only up to a certain point. In cases of fevers, inflamma- tion, &c., where the food ingested is comparatively small in quantity, and frequently not equivalent to more than 5 grams urea, a great pait of the excreted urea must be due to tissue waste. Thus, take a case of pneumonia with a daily excretion of 28 grams urea ; 28 — 5 = 23 grams would then arise from waste of tissue, and calculating this as muscle waste would give 13*72 x 23 = 315*56 grams of daily muscle waste. Amount ofUrea Excreted. — Among different individuals the difference in the amount excreted in the twenty-four hours is so great that it is almost impossible to strike a mean. The follow- ing estimates have been given for the twenty-four hours: — 17-5 to 23-5 grams, or 270 to 360 grains (Flugge). 300 „ 350 „ 4(;0 „ 540 „ CVoit). 250 „ 400 ., 390 „ 620 „ (Vogel). 34-8 „ 537 „ (Oppenheim and Meyer). The ivflup.nces nffcctmfj the ariumnt are various. 1. Constitution, Sex, Age, and Body Weight. — According to most aiitlioritics the mean for healthy men may be taken as 34 grams (o25 grains) in the 24 hours, or 0'5 gram for each kilo, of body weight; and for women, a mean of 25 grams (386 grains), or 0*4 gram per kilo. Calculated after TJhi>e's data the urea is excreted at the rate of about 3^ grains to each pound of body weight. In children the excretion of urea in proportion to the body weight is nearly double that of the adult period ; but up to one month it is SOURCES a:nd amount of urea. 4yi said only to be 0"23 gram for each kilo, of boily weight (Pahrot and Robin). In old wje it sinks again nearly to the half (Uule). While, it should be observed, an increase in body weight is attended with in- creased excretion of urea, the two do not bear a direct proportion to each other. 2. The character and amount of the food has the greatest effect on the amount, this reaching its maximum some six hours after the meal, and sinking to a minimum in the early morning. The dis- charge of urea is in propoi'tion to the amount of nitrogenous food ingested, and witli the urea thus discharged it would appear that one-seventh of the latent or potential energy of this kind of food escapes in an unexpended state. Fasting lowers the urea by 10 to 11 grams ; excessive consumption of water may raise it by 5 grams. Grams in the 24 hours With pure auimal diet . . 51 to 92 „ mixed „ . . 36 „ 38 „ vegetable „ . . 24 „ 28 „ non-nitrogenous diet . 16 (Frank). In a series of experiments made by Oppenheim upon himself he found that on a diet consisting of 400 grams bread, 300 grams meat, and 9.50 grams milk the urea eliminated after four days became very constant. The mean of seven days gave 34-6 grams=16"2 grams nitrogen; I'l gram was passed in the faeces. The total nitrogen in the food was=18*9 grams, and the nitrogen excreted 17*3 grams, the difference, 1'6 gram, being retained in the body. The maximum corresponded to the time of taking the largest amount of albuminoids as food. In the first four hours after the midday meal 2 4 gram was eliminated per hour in excess of the average ; during the night the excretion fell below the average. A 24 hours' fast caused an elimination of 10 to 11 grams below the usual amount. The quantity was raised by the ingestion of large quantities of fluid and of quinine. Coffiee exerted little effect, and the same was the case after excessive perspiration. 3. The varying organic metamorphoses occurring in the body dependent on the physical and mental activity, d'c, affect the urea considerably. But the weight of evidence is noAv entirely in favour of regarding muscle work as not tending to increase the amount of urea excreted (Voit), or to do so only to a very slight extent (Parkes), and that only after excessive muscular exertion (Noyes, Engelmann) ; so that it is most likely that the muscle works at the expense of the carbohydrates and fats ingested instead of the albu- 432 EXCRETA: THE F.ECES AND URINE. mins. It is possible that when the urea is increased daring muscular exertion it may be due to some accompanying dyspnoea, and dyspnoja, according to Fraenkel, causes an increased decomposition of albumin. Kellner's investigations with horses, however, show that an increase in the daily work led to an increase in the nitrogenous materials excreted in the urine — an increase that disappeared when the work was lessened, and that tliese results ensued with food rich or poor in proteids. But it may be stated generally that muscle work does not produce ani/ increase in the elimination of nitrogen unless the supply of carbohydrates for the purpose fails. During the day there is an average excretion of 1"4 gram per hour, and during the night 1"07 gram (E. Smith). An elevated temperature lowers the amount of urea ; on the other hand, an hour's immersion in a bath at 39"5° increased the urea one-third (Schleich). 4. Influence of Drugs. — While diuretics increase the amount of water they do not necessarily augment the urea. Thus alcohol and digitalis in sufficient doses diminish the urea. A similar diminution is effected by mercurial prejjarations. Phosphorus in poisonous doses lessens the urea, producing, after a time, fatty degeneration of the kidney. Arsenic and alcohol are said to produce a similar result, but the action is both slower and weaker. Plbosjihorus as well as arsenic probably induce a temporary increase, for after a svibcutaneous injec- tion of phosphorus in olive oil the urea is found augmented (Caze- neuve). SidphoM of qicinine first lessens the uric acid and then the urea ; but the ingestion of 2 grams in 24 hours I'aised the elimination by 4 grams (Meyer and Oppenheim). The urea is also increased by the mineral acids and by excess of the alkaline chlorides. 5. Pathologically it is both diminished and increased, a diminu- tion indicating either a lessened activity in protein metamorphoses or a retention of urea in the body. (a) The amount is diminished in profuse sweating, diarrhoea, cholera, or any prolonged discharge from the body; in certain diseases of the kidneys, specially in the later stages of chronic Bright's disease ; in most chronic maladies or cachectic conditions, as in anaemia, leukaemia, osteomalacia, gout, and chronic rheumatism ; during the period of remissions of high fevers ; in severe neuralgia and certain other neuroses, as melancholia, liysteria, and catalepsy ; in some diseases of the liver, especially acute yellow atrophy ; and in lepra, pemphigus, &c. (b) It is increased at the beginning of the crisis in fevers, more or less in proportion to the elevation of temperature — this is well marked in typhus. In intermittent fevers the ui-ea and extractives increa-se before the .setting in of the cold stage, and attain their SOURCES AND AMOUNT OF UREA. 433 maxiiiiuiii iit the beginning of the hot stage. In pneumonia it increases timing the febiile period, tO to 70 grams being cHniinated daily, but after al>out the Ofth day the amount generally falls to 25 to 28 grams. In diabetes more urea is excreted than by a healthy person on the same diet, and in an amount containing more nitrogen than can be accounted for by the food ingested ; an increased con- sumption must therefore occur in the albumin of the tissues, and the urea may rise to 150 grams (2,315 grs.) An increase is also seen in meningitis, pleurisy, acute tuberculosis, acute rheumatism with endocarditis, pytemia, and hepatic congestion ; temporarily also during the absorption of transudations and after bleeding. In phthisis moie niti-ogeii may be eliminated in the urea than is present in the food consumed (OrPENiiEiM). When the mine is not secreted, or if secreted is retained in any way, either from removal of the kidneys or occlusion of the ureters, kc, its constituents accumulate in the blood and organs. After a time the condition termed uroniiia is develoj)ed, not solely, be it remembered, as the result of the retention of urea or its factors in the system, but also in part from the retention of the extractives and salts, such as the i»hos])hates and sulphates of potash, kc. In uraemia the muscles and neives are affected, a sense of fatigue, muscular debility, and great drowsiness being established, and finally coma terminating in death, these symptoms being generally accompanied by vomiting, cramps, and convulsions. Zaleskv's experiments appear to show that the muscular debility and somnolence are the only constant symptoms, and that these are not dependent on the change's resulting from the decomposition of urea into ammonium carbonate, as suggested by Munk. Instead of an accunuilation of urea or excess of carbonic acid or ammonic carbonate in the blood and tissues Oppler and Zalesky found a marked accumulation of kreatin or kreatinin. But other observers have noted an increase of the urea in the 24 hours of 0026 to 0'206 and 0-276 per cent. ; the results being the same whether the kidneys were removed or the ureters tied, as the distension of the tubules in the latter case soon rendered the epithelium incapable of performing its functions (Grbhant, Gscheidlen). Part of the urea that is ponred out in some of these cases into the intestine is very pi-obably decomposed into ammonic carbonate, and possibly accounts for the cramps and vomiting. In the vomit and stools of cholera carbonate of ammonia, most likely derived in this way, is often present in abundance. F F 434 EXCRETA: THE F.ECES AND URINE. CHAPTEK VII. Q UA XTU\ 1 TI \ 'E DETERMINA TION OF UR EA . In any quantitative or volumetric analysis of the urine, as " tliis fluid varies so much in composition at different times of the day and night, owing to the varying conditions of alimen- tation, exercise, &c., the experiments to be of value should be made with portions of the mixed total urine passed in the 24 hours. To collect the urine, vessels of two litres' capacity are generally sufficient, unless in cases of diabetes mellitus. If sediments form the supernatant liquid is employed. A. Liebig's Method {Titration luitJi Mercuric Nitrate^. In this method the mixture of urine and baryta is not neu- tralised during the addition of the mercuric nitrate, and the end of the reaction is determined by allowing a drop of the mix- ture to run into a drop of saturated solution of sodic carbonate on a white tile, 10 c.c. of Liebig's solution — made by dissolving 71 '5 grams mercury in nitric acid and diluting up to a litre — being equivalent to 0*1 gram urea. A. Principle of the Method. — If to a dilute solution of urea (about 2 per cent.) a weak mercuric nitrate solution is added, an abundant white precipitate is formed, having the composition (CON2H4)2Hg(N03)2-r3HgO, and containing urea and mercuric oxide in the proportion of 10 tOj72 : — (CON^HJ^ = 120 Hg(N()3)2 = 216HgO 3HgO = 648. Accordingly a solution of 72 grams of mercuric oxide in nitric acid and diluted to 1,000 c.c. should exactly precipitate a solution containing 10 grams of urea. 2CON2H^4-4Hg(N03)2 f SH./) = [2CON^II,(N03)2Hg + 3IIgO] + GHNO3. A solu- lioi) of sodic carbonate gives a yellow precipitate with mercuric oxide. If therefore a portion of the mixtm'e of the urea and mercuric nitrate is removed and tested fiom time to time with the sodic carbonate, only a white precipitate will be obtained until the whole of thi' ui'ca has been com])i)icd witli the QUANTITATIVE DETERMINATION OF UREA. 435 mercuric nitrate, and an excess of tlic latter is present ; when this occnrs a little of the mixture tested with .sodic carbonate will give the yellow precipitate. To obtain this reaction, how- ever, a slight excess of the mercuric nitrate must be present, according to LiEHUf 5*2 milligrams for every c.c. of the mercuric solution, or 5*2 grams for thosed. — 1. It is said that much better results are obtained by first mixing the solution of urea with caustic soda and then adding the bromine so as to form the hypoljromite in presence of the urea. Experimenting in this manner 99'02 to 9991 per cent, of the whole nitrogen has been obtained (Duggan). The I''iG. 31.— Simpson's Ukea Appakatls. soda solution is made by dissolving 20 grams caustic soda in 100 c.c. water, and with every 20 c.c. of this liquid there should be used 1 c.c. bromine. The measuring out of the bromine is facilitated by intro- ducing a few drops of water into the tube containing it, which will float on the top and prevent to a great extent the escape of the bromine vapour. 2. WoRMLEY prepares the reagent fresh : 100 grams soda being dissolved in water 250 c.c, and 25 c.c. bromine added when the mixture has cooled ; this reagent is to be diluted before use with a volume and a half of pure water, and the urea solution is to be added to the reagent in small portions at a time, all effervescence being allowed to cease before any further addition of the urea ; the amount of urea also is not to exceed 1 part to about 1,200 parts of the diluted rea:fent. 448 EXCRETA: THE I.ECES AM) UEiIXE. With Simpson's appjinitus I have obtained most satisfactory result's, pai-ticuhirly with freshly prepared hypobromite solution, C. Arnold finds that Hufnee's apparatus yields as good results as Simpson's onh' when tlie solution contains 1 per cent, of urea: and that, compared with a direct estimation of the urea in urine by soda lime, Hiifner's method yields results 7 per cent, too low, and Liebig's process only 0"5 per cent, too low. C. Other methods have been employed for the estimation of urea, but only some of these will be referred to, and that in tlie briefest possible way. (a) Bunsen's process, which is very accuiate, and depends on the decomposition of urea effected by barium chloride at 220°, ammonium carbonate being first formed, which combines with the barium chloride. The carbonate of baryta is insoluble, and can be removed by filtration, dried, and weighed ; or dissolved in hydro- chloric acid and precipitated from its hot acid solution in tlie form of sulphate, which is to be washed, dried, heated on platinum foil, and weighed. 233 parts of the sulphate correspond to 60 parts of urea. (h) By the Will-Yaerentrap method some of the urine is mixed with caustic soda and heated so as to evolve its nitrogen in the form of ammonia, which is collected in sulphuric acid of known strength. From the loss in acidity, ascertained Vjy titration, the amount of urea is calculated. (c) Heixtz and Ragsky determined the urea by heating the urine with strong sulphuric acid, by which means sulphate of ammonia was formed and carbonic acid evolved. The ammonia was then precipitated with platinic chloride, and from the weight of the double chloride fonned the ammonia present calculated. (d) By the process of Ne'slerisiwj the urea can be determined, 10 c.c. of a 1 per cent, solution of urine being heated to dryness over an oil bath at 1 50° in a small retort with caustic potash, and then again aft'.T 20 c.c. ammonia-free water have been added to it. The distillate is diluted up to 60 c.c. and then Nesslerised (Wanklyn). CHAPTEK Vlll. URIC A (JIT). URIC ACID, O.H^N^O.,; molecular weight 1G8 ; containing 33"33 per cent, nitrogen. — It exists in the blood as a urate and is separated as such, but a decomposition of this urate occurs in the kidneys or bla^ldfr, or more frequently after emission. URIC ACID. 449 Normally also it is met with in the spleen, and traces of it have bean found in the brain, pancreas, liver, lungs, and heart. It is very rich in the urine of birds and reptiles, in which it re- places urea, but only in small amount in human urine, although occasionally presenting itself as a sandy sediment or orange- coloured crystalline powder. Although mic acid can be made by its decomposition to form urea, and may therefore be re- garded as a less oxidised product of proteid metabolism, it cannot be regarded as a necessary antecedent of urea ; indeed, it would rather seem that its formation is the result of a different metabolism to that which normally results in the pro- duction of m"ea. In the organism of the domestic hen the amido-acids pass into uric acid, as has been established in the cases of leucin and tyrosin (Knieriem); and here experiments appear to show that uric acid is not a dkect decomposition pro- duct of albumin, but rather the result of a synthesis that has its seat probably in the spleen (Eanke). In mammals too it is still doubtful Avhether the uric acid is a decomposition pro- duct preceding urea, although it seems probable that part of it at least is thus derived. Quantiti/ Excreted. — In the new born the quantity is pro- portionally greater than in the adult, forming 0*13 per cent, of the urine passed in the first week, then decreasing up to 0*04 per cent., an adult secreting on an average 9^ to 10^ grs. (Eanke) in the 24 hours, or about 0-03 to 0-05 per cent, of the urine (Parkes). Its excretion is somewhat less in women than in men, but the difference among different individuals, and even in the same individuals is very great. Its amount depends somewhat on the activity of the skin, with profuse perspirations the uric acid diminishing, but when the skin is comparatively inactive, as in winter, the uric acid increasing (Fourcroy). It is increased by animal food, particularly with insufficient exercise, and diminished by vegetable food. It is also increased by muscular fatigue (Eanke), although active outdoor exercise lessens it. Large doses of quinine and sodic carbonate (Seegen) reduce its discharge, as also inhalation of oxygen (Eckart), G G 4.30 EXCRETA: THE F.ECES u-LND URINE. Preparation. — (1) Excrement of serpents, Peruvian gumo, or uric acid calculi can be used. Powder finely, and after having ex- tracted with dilute hydrochloric acid boil with dilute caustic soda (1:20 water) as long as ammonia is evolved ; filter hot, dilute, and add some warm hydrochloric acid in excess, or pass a curi'ent of carbonic acid to complete neutralisation ; the uric acid separates as a tine white powdei', which is to be well washed with water and dried. By redissolving it in caustic soda and precipitating again with hydro- chloric acid it is obtained comparatively pure, when it is to be well, washed in water and then dried. The product thus obtained is yellow-coloured, but it can be rendered colourless by dissolving it in strong sulphuric acid and then precipitating with water. (2) To prepare it from human ui'ine add to this one-fifth its volume of hych-ochloric acid, which decomposes the urates, lay aside in a cool place, and decant after two or three days ; dissol ve the deposit of crystals on the walls of the vessel in sulphuric acid, and pi^ecipitate with water. As the uric acid is in such small quantity, it is generally advisable to concentrate the urine, particularly if of low sp. gravity, to half its volume before adding the hydrochloric acid. Properties. — Uric acid forms, when pure, a white crystalline powder that is devoid of taste or smell, but when impure it is generally of a yellow or brown colour ; it is almost insoluble in cold water and only slightly soluble in hot water (1 in 1800), very slightly soluble in alcohol and ether, easily soluble without decomposition in strong sulphuric acid and reprecipitated again on dilution with water ; likewise easily soluble in nitric acid, but with attendant decomposition; soluble in caustic soda and potash, but less so in ammonia ; soluble likewise in alk;iline solutions of lactates, acetates, carbonates, phosphates, and borates forming neutral lu'ates ; moderately soluble also in boiling glycerin, but more so in a boiling solution of sodic phosphate. Under the microscope uric acid is seen to assume a multi- plicity of c)-ystallinc forms. The most constant appeal's to be the rhoiiihic, frequently with the two obtuse angles rounded. The f«irm is affected by the strength and quantity of the acid added, and by the presence of other bodies (Ord). When i)re-- cipitated from an alkaline solution by means of hydrochloric acid it forms small transparent rhombic tables, with a few URIC A cm. 4ol elliptical and oljlong i»latps. Anioiig tlic forms occnrriiig in urinary de^onts the oblong or large hone-shaped form is charac- teristic. They may also occur as rhombic prisms or derivatives thereof, or in doubly convex, lozenge-shaped ])lates, elongated flat plates with excavated ends, rectangular quad- rilateral prisms, and dumb-bell-like bundles. The crystals may be separate or arranged in stellate groups. They are nearly always co- loured. Indeed, every crystalline urinary de- posit of a distinct yel- loiu, broion, or red colour may be said to consist of uric acid. The urine de- positing uric acid is also generally high-coloured and acid. Combinations. — It constitutes a weak dibasic acid, funiisLing acid (C'.r,MH3N403) and neutral salts (C.5M2H2N4O3) ; the latter are more soluble than the foriuer. These are a few of its soda salts : — Fig. 32.— Crystals of Tkic Acid. At (I arc crystals formeci by the arldition of hydrochloric acid to a sohition of uric acid in caustic potash. The rest are different fomis of spoutaiieously separated crystals. Urate of sodium Acid „ „ Quadriurate ., Na.X'gHsN^Oa + H.O 2(NaC5H3N403) + H20 NaC,H3N403-hC,H4N403 The acid urates are more permanent lluiii the neutral urates. There are similar urates of potass, ammonia, lithia, and lime. The urate of lithium is the most soluble in water, and that is why salts of lithia are prescribed Avhen an excess of uric acid is supposed to exist in the system ; and the sodic urates are more soluble than those of potash or ammonia ; the normal also are more soluble tbaii the acid, salts. As uric acid is a weak acid its combinations are readily decomposed even by acetic acid, but it possesses the power of de- composing the alkaline phosphates, forming a uiate and an acid phosphate. Decompositions. — These are most interesting as indicating some of the important relationships of uric acid. 452 EXCRETA: THE F.ECE.S AND URINE. 1. Uric acid is easily oxidised. By means of potassic perman- ganate it forms methyl allantoin and carbonic anhydride : C5H4N4O3 + + 2H,0=C,H5(CH3)N403 + CO^. 2. If the decomposition occurs at a high temperature oxalic acid and urea also appear, while if heated some time with plumbic oxide allantoin, virea, oxalic acid, and carbonic anhydride are formed. 3. Treated with cold nitric acid it furnishes alloxan and ui'ca : C5H4N4O3 + O + B.^O=0^-R^^^O^ + CON2H4. 4. Heated with nitric acid, carbonic anhydride and nitrogen gas ai'e given off, and alloxan, alloxantin, and urea are left behind. 5. By oxidation with alkalies allantoin and carbonic anhydride are formed: CJl4N,03 + H20 + 0=C4HoN"403 + C02. By further hydration allanturic acid and urea are obtained : C4H6N4O3 + H20=CON2H4 + C3H4N2O. In nearly all these decompositions of a molecule of uric acid it Avill be seen that two molecules of urea and a carbon acid of some kind are formed. 6. Heated in a sealed tube with strong hydrochloric acid it is decomposed into glycocin, carbonic anhydride, and ammonia : C.^H4N403 + .5H.,0=C,H5N02 + 3C02 + 3NH3. The converse syn- thesis of uric acid by fusing together glycocin and urea at a tempera- ture of 200° to 230° has also been effected by Horbaczewski. 7. By reducing uric acid with a weak amalgam of sodium xanthin (C.jHjNjOo) and then hypoxanthin (C5H4]Sr40) are ob- tained. 8 Heated with hydriodic acid to 170° uric acid is decomposed into glycocin, ammonium iodide, and carbonic anhydride : C,H4N403 -I- SHI -1- 5H20=C2H,N'02 -h 3NH4I -f SCOg. Tests and Reactions. 1. The Murexid Test. — Place the uric acid in a small porcelain dish, cover it with a few drops of nitric acid, and dissolve with the aid of heat, taking care not to let the temperature rise too high ; a yellow or reddish residue is soon obtained, wliich is to be moistened with a drop of ammonia, when a beautiful 'purple red colour appears. The body thus formed is named pnrpurate of ammonia {C^\{^{'^\{^)'^^0^), but it may be observed that the so-called purpuric acid has not been obtained free. If the uric acid is present in small amount add very little URIC ACID. 453 ammonia ; if is safer in sncli a case to expose tlu? residue to its va[)Our or to use a diluted ammonia (1 to 10). If the residue is treated with caustic potash or soda instead of ammonia a beautiful violet l)lue colour is obtained. The colour is dissipated by heat. (Caffein produces a somewhat similar reaction.) 2. Dissolve a little on a glass slide in a few drops of caustic potash with the aid of heat, and add a drop or two of hydro- chloric or acetic acid : note the transparent rhombic tables that are formed. The crystals of uric acid are so varied in shape that when in doubt it is always advisable to treat them as above, and obtain easily recognisable forms. 3. Dissolve a little uric acid in caustic soda, and having added a few drops of Fehling's solution, or of ammonia and dilute cupric sulphate solution, boil : the white cupric urate separates out ; after a time it takes a greenish tint. The cupric oxide must not be in excess ; otherwise the red cuprous oxide may appear. 4. Dissolve a little uric acid in as little sodic carbonate solution as possible, and, after moistening a piece of filter paper with solution of silver nitrate, by means of a glass rod bring a little uric acid solution down upon the filter paper : a dark spot of reduced silver immediately appears (Schiff). 5. If to a little of the solution in the sodic carbonate ammo- nium chloride is added, a gelatinous precipitate of urate of ammonia is obtained. G. Add a little solution of uric acid to some sodic hypochlorite in caustic soda : a rosy red coloration is produced, which dis- appears in excess of the soda (Dietrich). To Deter7)iine the Presence of Uric Acid in Urine and Aftcertain its Amount ajjjjroximately, cOc. — 1. The presence of uric acid or a urate in an animal fluid may be thus detected : Place the fluid in a watch glass and add a few drops of glacial acetic acid. A few fine filaments of flax or silk are immersed in it, and the whole laid aside under a glass shade for 24 to 48 hours ; the filaments are then to be removed and examined microscopically in a little glycerin (Garrod). The separation of the uric acid can be readily effected by boiling the fluid or extract to coagulate an}' albumin that may be present, then 454 EXCRETA: THE E.ECES AND URINE. filtering, and evaporating to dryness. The dry residue is to be repeatedly extracted with boiling water, and this extract acidified with acetic acid and laid aside for 24 to 48 hours. In gout the uric acid is generally present in sufficient quantity in .the blood to be obtained in the above way in the fluid taken from a blister, but while it accumulates in the body in chronic gout its excretion in the urine diminishes. This is frequently the case in many other diseased conditions in which the uric acid in the urine is diminished ; thus in Bright's disease the uric acid in the blood may rise as high as 0*12 to 0-55 (Garrod). 2. In most cases it may be separated by filtering TOO c.c. of the fluid, adding to it 5 c.c. hydrochloric acid, and laying the mixture aside for 24 hours. A deposit of uric acid gene- rally occurs, but the amount cannot be accurately estimated from the quantity of deposit present, although approximative results may be thus obtained. {a) After Heintz's method 200 c.c. urine are treated with 10 c.c. hydrochloric acid and left in a cool place for 48 hours. The crystals are then collected on a weighed filter, well washed with cold water, dried some hours between watch glasses, and weighed. Too low a result is generally obtained, but, in order to make up for the loss by the uric acid held in solution, to this should be added 0'0038 gram uric acid for every 100 c.c. of fluid that has been employed. (h) Evaporate one-fourth of the ui'ine p.assed in the 24 hours to 40 or 50 c.c, having first neutralised it with hydrochloric aciSOg + H2O), adding a little hydrochloric acid, boiling some minutes, and collecting the crystalline deposit of fine needles on cooling. The thionui'ate is obtained by passing a current of sulphurous acid for some time into a cold saturated solution of alloxan, then adding ammonium carbonate and boiling for half an hour. On cooling the thionurate separates. It is to be washed, dissolved in hot water, the boiling solution pre- cipitated with acetate of lead, and the thionurate of lead collected, washed, suspended in cold water, and decomposed with hydric sulphide. The filtrate is concentrated at 140° to a small bulk until crystals begin to separate. Purpuric Acid and Murexid. — The acid is not known in the free state, but it exists in murexid, which is the acid purpurate of ammonia. The murexid can be obtained by the electrolysis of alloxan, by heating ammonium dialuiate, by the action of ammonium carbonate on warm solution of alloxantin or alloxan, by heating dry alloxantin at 100° with ammonia gas, and by evaporating a solution of uric acid in nitric acid and heating the residue with ammonia : C5H„N,03 + 1I.,0 H- 0=C4H,N20, + C0(NH,)2 ; (■alloxan) 304N2H,O,=C«N,,H„O- + C3N JI,03 + CO.; (alloxantin) fpanibanii' aciil) CsN.H.O, + 2NH3=C JT«N,0, + IL.O. (niuiexid) Murexid can be best j)rej)ared by heating uramil ( t) and meicuric oxide (1) in water (30), adding a few dropsof ammonia, heating gently up to boiling point, and, after boiling a few minvxtes, filtering. Murexid forms four-sided tables or columns that are of a rod garnet hue with transmitted and n niciallic lm'omi with reficcted URATES A.SD URIC ACID DERIVATIVES. 450 light. Its .S()liiti()n in l>oiling water lias a purple tint; in alcohol aiul ether it is iusoluble. When warmed with acids it decomposes into iiramil, alloxan, and ammonia, and the alloxan still further into alloxantin and urea. Parabanic Acid, C^H^N^Oa. — It is prepared by rapidly transfer- ring uric acid (1 part) in small jiortions at a time to G parts nitric acid (sp. gr. 1-3) heated up to 70°. When effervescence has ceased the solution is evaporated to a syrupy consistence at the same tempe- rature. On cooling crystals separate, which are to be collected on a filter and dissolved in hot water (H pn.rt), from which pure para- banic acid is deposited. It forms thin, colourless, six-sided prisms, and its solution gives a white granular precipitate with silver nitrate, which is soluble in ammonia: CgAgoNaOg-l-IIgO. Allantoin (04115X40;)). — This body is found in the human allan- toic fluid and in the urine of young sucking calves; it occurs in very small amount in normal human urine, particularly in that of a new-born child for the fii-st few weeks after birth, during pregnancy (GussEROw), and after the ingestion of tannic acid. It has also been found in the lu-ine of dogs after the administration of uric acid (Salkowski), and in respiratory obstruction (Frekichs). It is gene- rally abundant in the urine of cats. In the placenta of both dogs and cats crystals of allantoin are found, often associated with hsematoidin and occasionally htemoglobin crystals, and also biliverdin. It is prepared by rubbing up uric acid (3) with water, and adding to it potassic permanganate (1), taking care not to let the tempera- ture rise ; filter rapidly, and having saturated the filtrate with acetic acid, leave aside 24 hours to crystallise. Its deiivation from uric acid may be thus expressed : C,H4N403 + + H20=04H6N40.3 4- CO,. It also may be obtained by evaporating allantoic fluid, the crystals being washed in water, and their solution in hot water decolourised with animal charcoal. To separate it from urine precipitate with lead acetate, filter, and, having passed hydric sulphide through the filtrate, evaporate it to a syrup and let it stand for several days. The crystalline mass is to be washed in cold and dissolved in hot water, from which the allantoin is allowed to separate. It crystallises in small, colourless, glistening prisms, and is slightly soluble in cold and more soluble in hot water, but insoluble in cold alcohol and ether. Its solutions are neutral, giving no precipitate 460 J'JXCBFTA: THE F.F.CES AND UEINE. with mercuric chloride, but a precipitate with mercuiic nitrate (2[C4N4H505]o-Hg+3HgO) ; silver nitrate also gives a white crys- talline precipitate. It is decomposed by concentrated alkalies : 3(C\H6N403)fl3H20=12NH3 + 6CO, + 2(C2HA) + C2H402. CHAPTER X. Ill P PUBIC ACID. HIPPURIC ACID, C9H9NO3, may be regarded as benzuyi glycocin, Qj^^Q.'^XT)^0^^ a glycocin in which an atom of hydrogen is displaced by the radical benzoyl CgH,.CO. It is a more important constituent of the mine of herbivora than of camivora, though it exists in considerable amount in animals living on a mixed diet. It is probably present in com- bination with one of the alkalies. Orifjin and Amount. — It arises in part from the oxidation of albumins, and in part also from such acids as the benzoic and cinnamic, &c., when absorbed. A vegetable diet, and par- ticularly fruit like greengages, blackberries, and plums, which contain benzoic acid, increase its amount in the mine ; the use of different balsams also has a similar effect. In the urine of different individuals it averages from 0*02 to 0*06 per cent. In starvation its elimination does not appear to be affected, for in a c»se where the urea excreted amounted only to 6'G grams and the uric acid to 0*07 gi-am the hippuric acid was J '16 gram. Occasionally its discharge undergoes a great increase, and Bouciiardat has described such a condi- tion under the name hippuria. Benzoic acid, when ingested, is changed in the liver, kidneys, or alimentary canal into hi})puric acid. But this power of changing benzoic into hippuric acid seems to be reduced in certain affections of the kidney, such as amyloid degeneration and acute and chr(^)nic inflammations. Occasionally in jaundice hippuiic acid has not been found even after the administration of benzoic acid. In some cases of diabetes it is increased, but in others it has llirPUIlIC ACID. 401 been noticed to be diminished, and in icterus and some kidney atfecti< ns it is diminished. It has been met with in the sweat also, especially after the use of benzoic acid and certain balsams. Lehmanx was of opinion that the increased acidity of the urine of fevers was due to this body, but recent investigations are ojiposed to this idea. Preparation. — 1. Boil the fresh urine of a horse or cow for some minutes with milk of lime in excess to remove the pigment, filter the hot fluid, and evaporate it rapidly to -j\jth its volume ; when cold, acidulate with hydrochloric acid. After 2-1 hours decant the fluid from the deposited brownish yellow crystals ; dissolve them up again in boiling milk of lime, tilter, to the hot filtrate add hydrochloric acid, and crystallise as before. The crystals may be rendered colourless by the action of animal charcoal or by heating their solution in excess of caustic soda with potassic permanganate solution, adding this body diop by drop to the boihng liquid until a little of the solution, when filtered, gives a pure white precipitate with hydrochloric acid. The whole fluid is then filtered and supersaturated with hydrochloric acid. 2. Treat the fresh urine with zinc sul])hate, evaporate to one-sixth the volume, filter, and decompose the zinc hippurate with hydro- chloric acid, and separate the hippuric acid by crystallisation. 3. To obtain it from liiinuin iirine give 30 grams benzoic acid to a patient in the evening, and the next morning collect his urine. Evaporate it to a small volume, and when it has cooled treat it with hydrochloric acid and lay it aside in a cool place. After some houi-s the deposit is collected on a filter and washed with cold water and alcohol. The crystals thus ohtained may be purified still further as in the first method. Properties. — Hippuric acid forms brilliant hard white anrj translucent four-sided rhombic prisms or needles, generally taking the form of prisms when deposited from a dilute, and of needles from a satmated, solution. The crystals are moderately soluble in hot water, and easily .soluble in alcohol and benzol, the solutions having an acid reaction ; soluble also in sodic phosphate, and in alkalies and their carbonates; but almost insoluble in ether and chloroform. Hippm'ic acid reduces an alkaline solution of cupric sulphate. It is monobasic and forms neutral salts that are generally 4G2 EXCREl'A: THE F.ECES AND URIXE. soluble in water and crystal] isable, tlie iron liippurate alone being araorpbons. Derivatives. — Wben boiled with strong mineral acids and alkalies it is split up into benzoic acid and glycocin : CH, (hippuric acid) (benzoic acid) (gljcociii) Ferments produce the same ejEfect; and a watery solution of hippuric acid to which sodic phosphate has been added, after a few days at a temperature of about 30°, undergoes a similar change. Heated strongly in a small tube it gives a sublimate of benzoic acid and ammonium benzoate, evolving, at the same time, an odour of new hay or bitter almonds, hydrocyanic acid and benzo-nitril being formed, and oily red drops deposited in the tube. Tests. — 1. Boil a little hippuric acid with a few drops of nitric acid, evaporate to dryness, and heat the residue in a small tube or porcelain capsule : an intense odour of nitro-benzene is evolved. Benzoic acid gives the same odour; but hippuric is distinguished from benzoic acid by its insolubility in ether and its non-volatilisation on being heated, also by the shape of its crystals. 2. Boil a little with strong hydrochloric acid, and the hippuric acid will break up into benzoic acid and glycocin. Add an excess of caustic potash and a drop of cupric sulphate solu- tion, fmd a deep blue coloration is produced, not destroyed by boiling: this is due to the glycocin. .3. To Detect in Urine. — (ft) Treat the urine with chloride and rnilk of lime to separate the phosphates, neutralise the filtrate with hydrochloric acid, and treat with nearly neutral ferric chloride, when a brown hippiuate is thrown down. By neutralising with sodic carbonate before filtration, then filtering, washing, and boiling the ]>recipitate with alcohol, thehi]»purate may be removed, and by lieat ing this with hydrochloric acid hippuric acid can be separated. (h) Evaporatf,' a litre of urine abnost to dryness: rub up the residue with baric sulphate, acidify with hydjochloric acid, and Ill IT URIC ACID. 4(}:j exhaust completely with alcohol ; neutralise the alcoholic ex- tract, distil off the alcohol, and having added a little oxalic acid evaporate to dryness. Exhaust the dry mass with ether to which some alcohol has been added, and eva[)orate the ethereal solution. Treat the residue with warm milk of lime, filter, and evaporate the filtrate to a small volume, which is finally to be acidified with hydrochloric acid. The hippuric acid crystallises out. HIPPURIC ACID DERIVATIVES— Benzoic Acid and Glycocin. Benzoic Acid, C7H502=CfiH5COOH.— This body exists ready formed in several balsams and resins, particularly gnm benzoin, and is found in the urine of tlie herbivora as a consequence of hippuric acid fermentation. It is occasionally met with also in the smegma pr.'eputii, sweat, and suprarenal capsules ; but it does not appear normally to be preformed in the organism. It can be produced by boiling a Vv'atery solution of hippuric acid with strong hydrochloric acid for an hour : C,H,(C7H,0)N02 + H20=C2H5N02 + CyHeOo. (hippuric acid) (glycociu) (benzoic acid) Properties. — Benzoic acid volatilises without decomposition at 240°, and is deposited in the form of fine elongated needles or thin, flexible, pearly plates. When ingested it passes out in the urine as hippuric acid. It dissolves readily in alcohol, ether, and ammonia, but only to a slight extent in boiling water. Pei'chloride of iron gives with benzoic acid or alkaline benzoates a brown precipitate of benzoate of iron. Solutions of free benzoic acid or its salts with the alkalies are not precipitated by a mixtui-e of alcohol, ammonia, and bai'ic chloride, thus differing from succinic acid, which is thereby l^recipitated. Derivatives. —If benzoic acid is moistened with nitric acid and evaporated in a small capsule it will give off the smell of nitro- benzol. Heated to redness with the caustic alkalies it evolves c-arbonic acid and lienzol. When acted on with sodium amalgam a solution of benzoic acid yields benzyl alcohol, O^H.^.CHa-OIE. By the distillation of ammonium benzoate with phosphoric anhy- dride a colourless oily fluid is obtained, benzonitril, CgH^.CN. Glycocin {Glycocol, Ghjcin), C2H.5NO, = CH2NH2COOH, ciys- tallises in large rhombohedra which are soluble in water, but insoluble in cold nlcohol and ether. It is a decomposition product formed by 464 EXCRETA: THE F.ECES AXE URIXE. the action of acitls or alkalies upon such animal substances as glue, gelatin, fibrin, and hippui-ic acid ; obtained also by the decomposition of glycocholic acid by boiling it with hydrochloric acid : Cj,H9N03 + H20=C2H5N02 + C7Hg02. (hippuric acid) (glyciii) (benzoic acid) It may be regarded as amido-acetic acid, as it is built up by the action of ammonia upon chloracetic acid : It appears to be allied to the cyanogen compounds, and a substitu- tion glycocin is sarcosin or methyl glycocin. Glycocin is not found preformed in the organism, although some regard it as a constituent of the liver ; but it can easily be formed there by the decomposition of such bodies as albumin and gelatin, a change that probably occui's in the liver ; for when benzoic acid is injected into the portal vein it is excreted by the urine as hippuric acid, but when rapidly injected into the jugular vein it passes into the urine unchanged (Kuhne). It is probable, however, that the conversion is not effected solely in the liver, but that the kidneys also assist (Sheppard). In the duodenum also it is possible that a similar decomposition occurs under the action of the pancreatic j uice. Preparation. — Boil impure hippuric acid for an hour with four times its weight of strong hydrochloric acid, and then evaporate nearly to dryness. Extiact the residue with a little water, boil this watery extract for a few minutes with freshly precipitated hydi'ated plumbic oxide, and separate the precipitated plumbic chloride by filtration ; pass hydric sulphide through the filtrate to complete the separation of the lead ; this final filtrate contains the glycocin, and is to be evaporated to a small bulk till crystallisation sets in. Also obtained by the action of acids or alkalies on gelatin. Derivatives. — Under the action of nitrous acid glycocin is changed into glycocollic acid (C2II4O3), water and nitrogen being evolved at the .same time. When heated with baryta it is decomposed into carbonic anhydride and methylamin : CH2.NH2.COOH + Ba(OH),=NH2CH3 + BaC03 + H,0. ((,'lycociii) (niotliylainiii) Ammonic permanganate in an ammoniacal solution oxidises it, there being formed carbonic acid, oxalic acid, oxamil (C'O.NHj.COOH), carbamic acid, and water. 40."5 CHAPTER XI. KREATIKIN. Of the remaining organic constituents we cannot do more here than refer to a few, such as kreatinin, indican, and the urinary pigments. 'CN KEEATININ, C4H„N30 orN^jJ^^^ (c,H,or This is a constant constituent of urine. It forms brilliant colomiess, oblique, rhombic prisms, and is supposed to be derived from the kreatin of muscle, as it is simply a dehydrated form of that body. An alkaline solution of kreatinin, for ex- ample, left to itself for some time changes into kreatin. Amount. — A grown man excretes in the 24 hours 0*5 to 1*3 gram, or a mean of 1 gram (Hofmann). Women excrete a little less than men ; infants on a pure milk diet excrete little or none; boys (10 to 12 years) excrete a mean of 0'387 gram, and old people a mean of 0*5 to 0*6 gram. Its proportion is increased by a rich flesh diet and diminished by abstinence. Pathologically it is increased in acute febrile processes, as typhus, pneumonia, and intermittent fever, and diminished during the convalescence of the same (Munk), being also lessened in anaemia, chlorosis, diabetes, chronic Bright 's disease, and tetanus. Preparation. 1. From Kreatin. — It can easily be prepared by evaporating to dryness a mixture of kreatin (1), water {?>), and sul- pliuric acid (1), then boiling the residue with freshly precipitated baric carbonate to separate the acid, filtering and evaporating; or by boiling the kreatin for half an hour with dilute hydrochloric acid, adding hydrated plumbic oxide, filtering, evaporating the filtrate to isnuith or lead, as these would produce a cloudiness in the liquid while being titrated, and thus interfere with the exact ending of the reaction being readily recognised. Pure mercury must therefore be employed, or, what will be better, pure red mercuric oxide. 18"42 grams of this oxide are 4S4 EXCBETA: THE F.FX'ES AXD URINE. placed in a be^iker with sufficient nitric acid to dissolve the oxide with the aid of a gentle heat, and when a clear solution is obtained it is evaporated to a SArupy consistence to expel excess of free acid. It is next diluted with water, and if the preliminary operations have been properly carried out a yellow precipitate of basic nitrate of mercury will be deposited, which must be allowed to settle ; the clear super- natant liquid is poui'ed off, and a few drops of nitric acid added to the precipitate to redissolve it. An excess of acid must be carefully i^uarded against, as it would materially interfere with the accuracy of the titration. The two fluids are then mixed and the solution (iraduo terl . 10 c.c. of the standard sodium chloride are poured into a beaker, and to this 3 c.c. of a 4 per cent. solvitioT of urea and 5 c.c. of saturated solution of sodic sulphate are added. The mercuric solution is now allowed to drop slowly into this mixture, the fluids being agitated with a glass rod, and the addition continued until a permanent precipitate is formed, any temporary opalescence being disregarded. If now, to produce this result, say 7 c.c. of the mer- curial solution were required, it is too strong and must be diluted with its own volume of water. Let the solution thus diluted be again titrated; and suppose 14 c.c. are required by the 10 c.c. of the sodic chloride solution to form a permanent precipitate, then to every 140 c.c. of the mercurial solution 60 c.c. of water must be added, so as to obtain a solution of which 20 c.c. shall be equal to 10 c.c. of the standard sodium chloride solution, and 100 c.c. exactly indicate 1 gram NaCl, or 1 c.c. = O'Ol or 10 milligrams. Before the urine can be titrated the "phosphoric acid present in it, which would precipitate the mercuric nitrate, must he removed. This is done by the addition of a haryta mixture thus prepai'ed : — Saturated solution of barium nitrate . . .1 volume Baryta water (saturated) . . . . .2 volumes Process. — 100 c.c. of the urine are mixed w-ith 50 c.c. of the baryta mixture, well shaken, and filtered. As the filtrate is alkaline it must first be cMrefully acidulated with a few drops of nitric acid, and 1.5 c.c. (= 10 c.c. urine) are taken and titrated with the mercuric solution. If the urine contains albumin this must first be removed by boil- ing the urine after it has been acidified with acetic acid. II. Mohr'.s Process. — To this process also there are many objec- tions in the case of urine, particularly when the chloride is present in Bmall amount, as in the urine of fevers ; but it serves very well when the chlorides are abundant. If nitrate of silver is added to a solution containing sodic chloride, neutral chromate of potash, and an alkaline phosphate, the chlorides THE INORGANIC CONSTITUENTS OF FlilNE. 485 will fii'st be precipitated, then the chromate, and lastly the phosphate, the production of a red coloration (due to the formation of chromato of silver) indicating the completion of the precipitation of tlie chloii'h?. This process of Moiir's lias been applied by Neubauer to the volu- metric analysis of chlorides in urine, neutral potassic chromate being used as the indicator. 1. Standard Silver Xilrate. — Dissolve 29 075 grams fused nitrate of silver in 1,000 c.c. distilled water : 1 c.c. = 0-01 NaOl. 2. Saturated Solution of Nexhtral Potassic Chromate. Process. — 10 c.c. ui-ine are diluted with 100 c.o. distilled water, and a few drops of potassic chromate added. The silver solution is now allowed to drop in slowly until the appearance of a trace of orange indicates the end of the reaction. Only in cases where the urine is not highly coloured can it be titrated direcilij as above. An excess of the silver solution is required, as the urine contains certain compounds more readily precipitable than the chromate ; accordingly 1 c.c. should be subtracted from the total number of c.c. of the silver solution used before making the cal- culation. But if the urine is high coloured, or at all decomposed, or contains excess of uric acid, mucus, or albumin, one of the following processes is to be adopted so as first to remove these organic com- pounds : — 1. Measure 10 c.c. of the urine into a platinum capsule, add to this 1 to 2 grams pure nitre, evapoi-ate to dryness, and then heat the residue carefully till the ash appears white ; allow to cool, dissolve iip the ash in water, and filter; acidulate the filtrate with dilute nitric acid, and having neutralised with carbonate of lime, add 2 or 3 drops of the ])otassic chromate and titivate with the silver solution. 2. Boil 10 c.c. of the urine with 5 c.c. of potassic permanganate solution (3"16 grams per litre), filter, and titrate as before. The pre- cipitate consists of organic matter and manganous salt, and enough permanganate should be used to give a slight rose tint to the filtrate : this is removed before titration by the addition of a few drops of solu- tion of oxalic acid. III. Folhard's Method as Modified hy Salkowski. — This is the most accurate process for the quantitative estimation of chlorides in urine. Principle. — If a little nitrate of silver solution is acidified with nitric acid, and some rhodium ammonio-chloride added, a white flocculent precipitate is thrown down ; while if an iron salt, such as iron ammonia alum, is also present, a red colour will appear imme- diately the whole of the silver has been precipitated. Now, if the rhodium solution is of kno^n strength, the amount of silver present 4SG EXCRETA : THE F.ECES AND URINE. can be readily calculated. Accordingly, if this method is employed in the estimation of chlorides, an excess of a titrated silver solution is added, and the amount of this excess determined by the I'hodium solution. Preparation of Solutions. 1. Silver Solution. — Dissolve in dis- tilled water pure fused nitrate of silver 29 '075 grams and make up to a litre. 1 c.c. = 0-01 gram NaCl. 2. Iron Solution. — Make a cold saturated solution of iron am- monia alum. This salt should be free from chlorides; if not, purify it by crystallisation. 3. Rhodium Solution. — The strength of the solution should bo such that 2.5 c.c. = 10 c.c. silver solution. Make a watery solution of commercial rhodium ammonio-chloride, about G'5 to 7 grams in 1,100 c.c, water. Dilute 10 c.c. of the silver solution to 100 c.c. with distilled water, add 4 c.c. pure nitric acid and 5 c.c. of the iron solution. Then titrate this mixture with the rhodium solution till a faint permanent led coloration is produced. If, say, only 23'8 c.c. instead of 25 have been required we must dilute accordingly : 23-8 : 2.5 = 1000 : x. X z= 1050'4. Therefore 50'4 c.c. water must be added to the litre. Process. — 10 c.c. urine are placed in a small glass-stoppered ilask, graduated .so as to contain 100 c.c. u]) to a mark in the neck. Add 50 c.c. water and then 4 c.c. pure nitric acid (1'2 sp, gr.) Now pour in 15 c.c. silver solution and shake vigorously until the precipi- tate settles. Next make up to the mark with distilled water and filter the contents of the flask into a dry test glass or a small flask which has a mark on its neck indicating 80 c.c. capacity. The 80 c.c. of filtrate are to be poured into a beaker of about 250 c.c. capacity, 5 c.c. iron solution addeil, and the mixture titrated with the rhodium solution until the first trace of a ^>er?».ftneni blood red coloration appears. Let us suppose that 6-8 c.c. rhodium solution have been required for 80 c.c. of the filtrate, therefore 85 c.c. for 100 (80 : 100 =G-8 : 8-5). Now the 15 c.c. silver solution added to the urine are equivalent to 37-5 rhodium solution (10 ; 15 = 25 : 37-5); but only 8-5 have been required; therefore 37-5 — 8-5 = 29 c.c. correspond to the silver solution that has combined with the chloride, and 29 c.c. are equivalent to 11-G silver solution (25 : 10 = 29 : 11-0). 1 c.c, silver solution = O'Ol NaCl; therefore 11-0 = 0-116 NaCl. As only 10 c.c. urine were em])loyed, this would give a j^ercentage of MGNaCl. The percentage is readily ohtiiiufil In (hu fullovviug formula, THE INORGANIC CONSTITUENTS OF URINE. A9>7 which will easil}'- be comprehended from the preceding calcula- tion : — (37 5— (rhodium solution requii-ed in c.c. x 4)} X y^^. IV. C. Arnold, so as to obviate any difficulty in noting the end of the reaction by means of the red coloration of the iron, first treats the urine with an equal volume of baryta mixture (see under I.), and adds to 10 c.c. of the filtrate, or even to 10 c.c. of the urine direct, as many drops of nitric acid as are necessary to give a strong acid reaction, then 2 c.c. of the iron solution and 3 or 4 drops of per- manganate of potash solution (1 : 30). The silver solution is next added in excess, the whole made up to 100 c.c, thrown on a dry filter, and 50 c.c. of the filtrate titrated with the ihodium solution as in III. to determine the excess of silver. CHAPTEK XVI. THE SULPHATES. SULPHURIC ACID (H,S04 = 98) exists in the urine com- liined with organic and inorganic bases, but chiefly in the form of sulphates of potash and soda. The sulphates are present in only very small quantity in the fluids of the body with the exception of the urine. But the urine also contains sulphur in a state of incomplete oxidation, and this in the urine of patients suffering from certain diseases of the liver may form as much as 40 per cent, of the total sulphur present. This sulphur, oxidised with difficulty, is generally regarded as arising from biliary compounds in the urine, particularly de- rivatives of taurin, the amount varying under different circum- stances, being generally large in constipation. To obtain this sulphur it is not sufficient to treat the urine with zinc and sulphuric acid and estimate the hydric sulphide evolved ; only by the use of such powerful oxidising reagents as nitric acid and potassic chlorate can the total amount be obtained (Lepine). The Origin of the Sulphuric Acid. — It arises chiefly in the decomposition of albumin in the system, as the sulphates taken in the food are very shght in amount. It is difficult to say. 488 EXCEKTA: THE F.ECES AXD URINE. however, how much is derived from tissue albumin and how much directly from food albumin. When the albumin of the food falls in amount, so also does the sulphuric acid of the urine ; in high fevers with much decomposition of organic albumin the sulphuric acid is likewise increased proportionally. The excretion of this acid woidd therefore appear to maintain a close relationship to the excretion of urea ; but it must be remembered that while the nitrogen of albumin is more or less a constant quantity (16 to 17 per cent.) the sulphur varies considerably (l*2o to 1*6 per cent.); also a part of the sulphur is excreted by the intestine, while the whole of the nitrogen of the decomposed albumin passes away by the urine. Further, the whole of the sulphur is not in the form of sulphates in the urine; only '6c) per cent, may be reckoned as such. Amount. — Adult men excrete a mean of 2 to 2*5 grams sulphuric acid, of which tlie potash salt forms about 4*3 grams and the soda salt 3"55 grams, or 0*032 gram of sulphuric acid per kilo, in the 24 hours : for women the mean is about l-9() gram. The quantity, however, varies even in the same indi- vidual from day to day, occasionally as much as 45 per cent, above or below the average mean. The elimination is increased when the minerals of the food are augmented ; an increase generally shows itself some hours after a meal, especially of animal food ; also after prolonged exercise (Engelmann, denied by Voit), and after ingestion of soluble sulphates, sulphuric acid, or bodies containing sulphur, and also temporarily after copious draughts of water. It is diminished by vegetable diet, and less is excreted during the night and during pregnancy. A ^pathological increase occurs after the ingestion of sulphur combinations, phenol, thymol, salicin, and liquor potassa? ; also in delirium tremens and in other deliriums (Bence Jones), in acute inflammatory diseases of the nervous structures, and in acute inflammations generally, as pneumonia and acute rheu- matism ; in some cases of diabetes insipidus, and occasionally in some forms of skin disease. The sulphates are slightly in- creased in fevers, but diminished considerably diu-ing conva- lescence (ZiJLZER), though according to some authorities they are diminished in all acute and many chronic febrile attacks ; THE ISIJLV HATES. 489 indeed, it ina_y be stiid that the sulphates are diminished to some degree in acute and chronic affections, probably on account of the lessened amount of food then absorbed. Like- wise diminished in leukccmia, diabetes mellitus, eczema; also in inflammatory affections with much nxudatiun, in chlorosis, and often in diseases oi the nervous system. Tests. — 1. Add some drops of hydrochloric acid to the urine, and then baric cJdoride. : a white precipitate of baric sulphate, insoluble in acids. 2. By acidifying the urine strongly with acetic acid, add- ing baric chloride, and then boiling, the preformed inorganic sulphates are thrown down ; but the filtrate, wlien strongly acidified with hydrochloric acid and boiled, gives a further pre- cipitate of sulphur, due to the organic sulphates. This separa- tion may be better effected thus: Mix equal volumes of urine and baryta mixture [cold saturated solution of hydrate of baryta (2) and nitrate of baryta (1 )] ; filter, and having acidulated the filtrate with hydrochloric acid, boil, and the second precipitate is thrown down. To avoid the difficulties encountered in the filtration of barium sulphate, silver nitrate should be added immediately after the precipitation of the sulphuric acid by the barium chloride ; a flocculent precipitate is thereby obtained, which can readily be filtered. Removal of the silver chloride is effected afterwards by ammonia without any loss of the sulphate. 3. Sulphuric acid gives a precipitate with chloride of lime in moderately concentrated solutions, the resulting sulphate, however, being soluble in a large volume of water ; also a white precipitate with lead acetate, soluble with difficulty in water and dilute acids. Quantitative Estimation. I. Gravimetric, (n) Of the Total Sulpliitric Acid. — Mix 100 c.c. clear filtered mine with 5 c.c. hydro- chloric acid (sp. gi\ 1'12), boil, and then add baric chloride to complete precipitation ; continue to boil for some time until the supernatant liquid is clear, and throw it upon a small filter of Swedish paper that has been washed with dilute hydrochloric acid, collecting all the precipitate upon the filter with the help of a glass rod tippeil with gum elastic. A little of the filtrate should early be tested with a drop of sulphui'ic acid, to ascertain the presence of 400 EXCRETA: THE F.ECES AAD URINE. excess of barium chloride. If this is the case wash the precipitate thoroughly with hot water, then with hot spirit, and afterwards with ether. Now dry the filter and its contents, and transfer them to a platinum capsule, where they are to be covered, heated to redness till quite white, allowed to cool, and then weighed. A slight loss occurs. (b) Estimation of the Hidpliv.ric Acid Comhined with Aromatic Organic Bases. — 100 c.c. urine and 100 c.c. baryta mixture {see under Urea) are mixed in a diy beakei', well shaken, and then thrown on a dry filter. Acidify 100 c.c. of the clear filtrate (=50 c.c. urine) strongly with hydrochloric acid, and boil for some time over a water bath until the precipitate is well settled down. Then proceed as above. C'rtZcM^aeiow.— 233BaSO4=98H,SO4=80SO3=32S. If we reckon as H2SO4, multiply the weight of BaS04 by ^=0-4206 ; if as SO3, then multiply by |^=0-3433 ; and if as S, by ^ =0-1373. lloo Zoo Example. — 100 c.c. mine gave 0'490 BaS04, then the H2SO4 =0-490 xO-I206=0-206 per cent,, and the 8 = 0-490x0-1373 =0-0672 per cent. II. Volumetric, (a) Standard Baric Chloride. — Some crystallised bai'ic chloride is powdered, dried between folds of blotting-paper, and 30-5 grams taken and dissolved in distilled water, the solution being made up to a litre, 1 c.c. =001 gram SO3. \b) A dilute solution of sodic sulphate is also prepared. Process. — Measure 100 c.c. mine into a beaker, acidify with a little hydrochloric acid, and boil in a sand bath ; let the baric chloride solution next flow gradually in so long as the precipitate distinctly increa.ses. Then lay aside to allow the precipitate to .subside ; let a drop of the baric chloride now flow down the side of the beaker, and if a precipitate occurs continue to add the baric cliloi-ide until the whole of the sulphuric acid appears to be thrown down, and let it settle as before. Instead of waiting until the pre- cipitate subsides, a little of the fluid may be filtered into a watch glass and tested with the baric solution, the whole being returned again to the beaker. This filtration may readily be eflected by dipping into the beaker a wide open tube, over whose lower end a piece of filter paper has been tied, and removing it after a short interval. Care must be taken that an excess of baric chloride is not added. Tliifl is ascertained by testing a drop of the filtrate upon a piece of gla-ss lying over a dark background with the sodic sulphate; if a pie- THE SULPHATES. 401 cipitate is obtained then too much baric chloride has been added, and the titi'ation must be repeated. Suppose 18 c.c. have been added to obtain complete precipitation, then 0-18 gram SO3 is present in the 100 c.c. urine. CHAPTER XVII. THE PHOSPHA TES. The phosphoric a,cid of the urine is in part (two-thirds) in com- bination with alkalies, and in part (one-third) with the alkaline earths, lime and magnesia. Of these there are the acid phos- phate of soda, NaHgPO^ + 11,0, to which Liebig ascribes in great part the acidity of the urine ; the alkaline phosphate, Na^HPO^, possibly only in small proportion, for although this phosphate is generally met with in all the animal fluids it is the acid salt that is found principally in the urine. A potash phosphate is present in small amount. But the composition of the phosphates in the urine is liable to considerable varia- tion : in acid urine the salts NaH2P04 or Ca(H2P04).3 are generally present ; when the urine is neutral, in addition to the above acid salts, we have NajHPO^, CaHPO^, MgHPO^ ; while in alkaline urines the combinations NagPOj, Ca.j(P(),,).^, Mg3(P04)2 may also be present. The alkaline phosphates are soluble in water, and are not pre- cipitated from their solutions by ammonia or the alkalies, so that when ammonia is .added to healtliy urine the alkaline phosphates are not thrown down. The earthy pho.tphates are insoluble in water, but readily soluble in such weak acids as carbonic and acetic ; albuminous bodies and njucus have likewise some power in dissolving these phosphates. They are precipitated from their solutions by ammonia. The ordinary phosjjhafe of soda is soluble in water and alcohol ; its aqueous solution has an alkaline reaction and absorbs carbonic anhydride very readily. When heated it melts, loses its water of crystallisation, and ultimately changes into the pyrophosphate. The acid phosp/iate, on the other hand, is changed by heat into the 492 EXCRETA ; THE FAECES AND UEINE. Tnetapliosp]iate, and is easily soluble in water, but insoluble in al- cohol. Uric acid has the power of decomposing the alkaline phosphates, a ui-ate and an acid phosphate being formed. The ainmoniaco-maynesian or triple 'phosphate (NH4MgP0, + GII2O) is met with in the urine and in the animal fluids when these are undergoing alterations. The crystals are generally well marked, being most fre- quently found as vortical, rhomboidal, or triangular prisms with obliquely truncated ends ; but if deposited rapidly from urine by the addition of ammonia, this phosphate may assume a stellate form, the crystals consisting of four or live feathery rays. Fk;. 3-1.— TrYSTAT.S of TIUPLK O j.- xl • IT 1 • r 1 J.1 PHdSPHATK. bometnnes a thm pellicle is lormed on the surface of urine, consisting of organic matter with numerous crystals of the triple phosphate. Fhosphute of lime is usually deposited in an amorphous condition, generally in minute transparent granules, but the deposit after a time may assume a crystalline form and appear as minute spherules or dumb-bells, or as fine needles grouped in globular masses. These cry.stals can be formed artificially by dissolving a little calcium chloride in a drop of glycerin, and a little phosphate of soda in another drop, and allowing the two drops to mix slowly under a cover glass : crystals will appear in a few days. Also by adding a little calcium chloride to normal urine, and nearly neutralising it with caustic soda, crystals of the calcic phosphate may be obtained. The urine from which one of these deposits occurs Ls generally alkaline. If uric acid, urates, and oxalate of lime are associated with the triple phosphate in a urinary sediment, they are thus dis- tinguished : — 1. Warm the urine: the urates dissolve. 2. Add acetic acid : the phosphates dissolve. 3. Add caustic j)otash : uric acid dissolves. 4. Examine the deposit microscopically and apply the mnrexid test. 5. Dis.solve in acetic acid and test with uranic nitrate for phos- phoric acid, and with oxalate of ammonia in excess for lime; filter and add ammonia to the filtrate, and magnesia is precipitated as the phosphate. Origin of Phosphoric Acid.— This acid is generally dist.ri- bnt(.-d iij the tissues of the body; it is also contained in the THE niOSrJfATES. 403 food, and it is probable that tlio greater part of the pliosphoric acid eliminated conies from the food ingested, partly as ])hosphates taken as such, and partly from phosphorus and phosphates previously combined with the proteids. About one- third to one-fourth, if not more, of these phosphates contained in the food, however, is excreted by the intestine. Another source of the phosphates is the decoinposition of such bodies as nuclein and lecithin, which contain phosphorus ; but the amount formed in nervous tissue is comparatively small. ZiJLZER estimates the proportion of phosphoric acid to every 1 00 parts by weight of nitrogen in the tissues as follows : blood 4, muscle 15, brain and nervous system 45, while in the urine the i)roportion varies from 18 to 20. Amount of Phosphoric Acid Excreted. — In the urine from 2'5 to 3'5 grams are excreted in the twenty-four hours, though it may rise to 5*5 ; the mean, however, may be taken as 2*8 grams, or 0*04 to 0*05 gram per kilo, of body weight, though it is given by Vogel as high as 3'5 grams for well-fed healthy adults, or 0*064 gram per kilo. It forms about 3'22 per cent, of the urinary solids. Of the earthy phosphates the mean is 1*1 gram, the calcic salt — 0-4 and the magnesic = 0"6 gram. The faeces also contain a variable proportion of phosphoric acid — a mean of 0-666 gram in the twenty-four hours, that is, one-fourth to one-fifth of the amount excreted in the urine (Haxthausen) — but the elimination by the f?eces is increased by an abundant ingestion of carbonate of lime, the effect only, however, lasting a couple of days or so (Kiessell). Variations. — Great difference of opinion exists as to the ehects of different physiological and pathological conditions of the body upon the elimination of phosphoric acid ; it is very probable that the amount excreted is not constant, but subject to considerable variation. (j) The food has an important influence, the phosphoric acid increasing for some hours after a meal, and diminishing during starvation or abstinence. The nature of the food has also an important effect, the phosphoric acid being more abundant after animal than vegetable food. A man upon a mixed diet elimi- nated in the urine the total phosphates contained in the food (Beale). 494 EXCRETA: THE F.ECES AND URIXE. An abundant ingestion of calcic carbonate increases the earthy phosphates ; and the excretion of these phosphates may be said to run more or less parallel with the decomposition of albumin, an animal diet greatly increasing their amount and abstinence diminishing them. A mixed diet gives of earthy })hosphates in a healthy man a mean of 0-944 to 1-012 gram (Neubauer), or 1*2 gram (Bencke) in the twenty-four hours. The presence of much soluble phosphates or of phosphorus- holding bodies in the diet increases the elimination, as also much consumption of fluids. The food further greatly in- fluences the proportion of the phosphoric acid to the nitrogen in the urine and faeces ; with much animal diet the proportion is 1 : 8-1, while with bread diet it is 1 : 3-3. Indeed, it is very probable that the altered diet in diseased conditions accounts largely for much of the alteration in the amount of phosphates excreted. (ij) Active exercise increases the phosphates (Hammond, Exgelmann, Pavy, Moslek), though this is denied (Pettkn- kofer, VoiT, Byasson). (iij) Cerebral activity increases it, but there is much difference of opinion as to this. While Mosler, Byasson, &c., maintain that the elimination of the acid in the urine is in- creased by brain work, Hodges Wood asserts that the total phosphoric acid remains constant, although the alkaline phos- phate increases and the earthy phosphate diminishes. (iv) Tirae of Day. — In the same individual the amount ex- creted exhibits considerable variation during the day. It increases after dinner, attaining its maximum in the evening, diminishes slightly during the night, and arrives at its mini- mum in the morning (Vogel). Its amount seems affected more or less by the same conditions as influence the amount of urea. (v) Sex appears to exercise little or no effect, but the amount is greatly diminished in pregnant women. (vj) Afje. — Children in the first eight days after birth excrete about 0-014 to 0-032 per cent. ])hosphoric acid as com- pared with 0*19 to 0-23 per cent, in the adult. The proportion also is mucb less in growing children than in adults. In young infants the f|iiantily of caitliy phos])hates is very small. TUB niOSniATES. 405 Reactions and Tests. — 1. Baric chloride or niirrtfe gives a. white preci[)itate of baric phosphate, which is soluble in hydro- chloric and nitric acids. To obtain this precipitate the acid phosphate must first be neutralised. 2. Add a little aniTnoniuiii chloride to some solution of sidphate of inarjnesia^ and then aniriionia in excess ; no pre- cipitation of the magnesia occurs in presence of the ammonium chloride. Now add this mixture to the phos])hate solution, and a white crystalline precipitate of the triple phos})hate will be formed, soluble in acetic acid. If the solutions are very dilute the precipitate takes some time to appear. 3. Nitrate of silver gives a yellow precipitate of the phos- phate of silver, easily soluble in nitric acid or ammonia. If a chloride is present this salt will be preci})itated first ; the same also occurs with a chromate, so that if silver nitrate is added to a solution containing sodic chloride, potassic chromate, and a phosphate, the chloride is precipitated first, then the chroTnate, and lastly the phosphate. 4. Molybdate of ammonia dissolved in nitric acid gives with a phosphate a yeUow, finely pulverulent precipitate, whose formation is favoured by a gentle heat. 5. Acidify the urine with a few drops of acetic acid, and add ferric cMoride: a thick yellowish white precipitate of ferric phosphate, which is easily soluble in the mineral acids, in the perchloride in excess, or in ammonia. If any free acid is present in the urine add acetate of soda and free acetic acid before adding the ferric chloride. 6. Acidify as before and add some uranic nitrate, preferably to boiling urine : a dirty white precipitate of uranic phosphate is formed, that is easily soluble in the mineral acids. 7. The earthy johosp hates in urine are precipitated by the addition of ammonia, stellate crystals being formed; filter and test the filtrate Avith ferric chloride after having acidified with acetic acid: a whitish yellow precipitate appears, indicating the presence of sodic phosphate. In the ammoniacal precipitate phosphate of lime and the triple phosphate are present. To separate the lime from the magnesia dissolve the precipitate in acetic acid, and add ammonium chloride and ammonium oxalate, when the lime will be thrown down ; while the magnesia is 408 EXCRETA: THE F.ECES AND URINE. separated from the filtrate in the form of triple phosphate by adding to it ammonia. To separate all the j^hosphates contained in urine add to the latter a solution containing sulphate of magnesia (1), dis- tilled water (8), ammonium chloride (1), and ammonia (44). They are deposited as the triple phosphate. Quantitative Estimation. I. Volwnetricalli/ hy viemos of a Standard Uranic Solution.— li to a solution of sodic phosphate' (NaoHPO^) acidified with acetic acid a solution of nitrate or acetate of uranium is added, we obtain a yellowish white precipitate, the \\hole of the phosphoric acid being thrown down as ru'anic phosphate : 4(UrO.NO.O + 2Na2HPO, = 2{Ur.,0.,)F,0r, + 4NaN03 + H2O. This precipitate has a molecular weight of 368 (Ur=120, H=l, 2(grO)=272, P04=95), corresponding to 71 PgOj or 98 H3PO4. Any excess of lu-anic salt is easily detected by testing a drop of the mixture with a drop of potassic ferrocyanide on a white porcelain plate, wbich gives a leddish brown precipitate with any uranic salt not combined with phosphoric acid. This body is therefore used as the indicator of the terminal reaction. To eflect the analysis a solution of known strength of the uranic salt is made, which for accuracy is titrated with a standard solution of sodic phosphate ; and to ensure the free acid of the urine being acetic, in which the precipitate is insoluble, this fluid is first treated with a solution of acetate of soda containing free acetic acid. But in presence of sodic acetate it should be noted that the reaction of the ferrocyanide with excess of uranic salt is not so sharp as with the pure salt, the production of the chocolate colour also being retai'ded. Preparation of the Solutions. — (a) The ferroci/anide solution con- sists of 1 of the salt in 20 of water freshly dissolved, (tj) The Acetate of Soda SoliUion. — Dissolve crystallised sodic acetate 100 grams in water, add strong acetic acid 100 c.c, and make up to 1,00 'J c.c. with watei'. (c) The Sodic Phosphate Solution. — Houghly powder some pure crystals of the phosphate (Na.^HPO^ + I2H.2O), and dry them between sheets of filter paper. Now Aveigh 10-085 grams and dissolve in 1 litre water. This solution will contain 0*2 P20r, in 100 c.c. (d) The firanic Solution. — This is best prepared so that 20 c.c. correspond to 50 c.c. of the sodic phosphate solution, and therefore to 0-1 gram Po'-'.-,- Accordingly the litre should contain 20"3 grams })ure uranic oxifle. THE PHOSPHATES. 497 Dissolve 33 grams yellow uianic oxide in nitric acid (sp. gr. 1"2), or in dilate acetic acid, and dilute up to 1,100 c.c. (An approxima- tive solution may also be obtained by dissolving 40 grams of the uranic acetate or nitrate in a litre of water to which 25 c.c. pure glacial acetic acid have been added.) Fill a burette with this solution ; measure 50 c.c. of the standard phosphate into a small l)eaker, and add to it 5 c.c. sodic acetate solu- tion ; some drops of the ferrocyanide ai-e next to \ic placed upon a white porcelain plate. Now boil the phos])hate solution in the small beaker, and allow about 18 c.c. uranic solution to flow into it ; boil again, and having stirred well, bring a drop of the mixture in contact with one of the drops of ferrocyanide (or biing a drop of the ferrocyanide into the centre of a drop of the mixture placed on the porcelain plate) : if a faint brown colour appears in a few seconds then an excess of the uranic .^alt has been added, but if no brown colour shows itself then more of the uranic solution is to be dropped in ; this addition must be made very gradually, and the mixture tested with the ferrocyanide after each addition. As soon as ever the reddish brown colour ap- pears lx)il the whole mixture again with frequent stirring, and repeat the ferrocyanide test. A second, and even a third, experiment should be made with the fiist as a guide, and great care taken with the final addition of the uranic solution, so as to have the least possible excess. Suppose instead of 20 c.c. only 19 "2 c c. were required, then the ''O solution must be diluted in this proportion : -'-— = 1-04166 litre, or to 1,000 c.c. of the ui-auic solution 41 '66 c.c. water added. It is better, however, to add less water than this at first, and to titrate again. 20 c.c. of the solution thus jnepared = 0-1 PjO.,. Titration of the Urine. (A Mohr's burette, a piece of white porcelain, and two pipettes, one for delivering 50 c.c. and the other 5 c.c, are required.) (j) To Obtain the Total Phosjyhoric Acid. — Heat to boiling 50 c.c. of the filtered urine to which 5 c.c. of the sodic acetate solution have been added ; then titrate with the uranic solu- tion as above, boiling and stirring well after each addition and testing a di-op from time to time with the ferrocyanide; continue to add the uranic solution so long as a precipitate is seen to occur, and till the brownish yellow colour is obtained as above with the ferrocyanide. Two 4eterminations must l^e made. If 22-5 c.c. uranic solution were required for the appearance of the terminal reaction, then (20 : 22-5 = O'l : 01125) 50 c.c. urine contain 01 125 gram P2O.5, or 2-25 grams in the litre. K K 498 EXCRETA: THE F.ECES A^'D URINE. It may be interesting and advantageous to know the amount of tlie phosphoric acid combined witli lime and magnesia ; this is done as follows : — (ij) I'd Estimate the Phosjjhoric Acid Combined with the Alkaline Eartlis. — Take 200 c c. filtered urine, render it freely alkaline with ammonia, and lay aside for 12 hours. Collect the precipitated earthy phosphates on a filter, where they are to be washed with ammoniacal water (1 to 3) ; and after having made a hole in the filter wash the jjrecipitate thi*ough with water containing a few drops of acetic acid into a small beaker, in which they are to be dissolved in as little acetic acid as possible with the aid of heat. Now add 5 c.c. of the sodic acetate solution, bring the volume up to 50 c.c, and titrate as before. If, for example, 10 5 c.c. of uranic solution have been required, then, as 10 c.c. of this solution = 0-0.5 P^O.,, 105 c.c. = 0-0525 gram '1*2^)5 in every 200 c.c. of the ui-ine, or 02625 P2O5 in the litre. (iij) To Obtain the Phosphoric Acid C omhined with the xilkalies . — Subtract the phosphoric acid of the earthy phosphates from the total phosphoric acid obtained, and the difference will be equal to the acid combined with alkalies. Thus- Total phosphoric acid ...... 2-25 Phosphoric acid combined with the alkaline earths . 0-262.5 „ „ „ alkalies . . l-!)875 II. Quantitatively by Precipitation loith Molybdate of Ammonia. — Teissier has employed a solution of molybdate of ammonia, made by dissolving 100 grams in 100 c.c. ammonia and adding the solu- tion slowly to 1,000 c.c. nitric acid. 5 c.c. urine are evaporated and the residue dissolved in 6 c.c. pure nitric acid ; to this 5 c.c. water are added and the solution filtered. Pour this into 5 c.c. of the molybdate solution contained in a capsule. The precipitate, having been allowed to settle, is collected, washed, dried, and weighed. The weight x 1-63 gives the phosphorus in 1 litre, or x 3-735 gives the phosphoric acid. The process is difficult but exact. 111. Teissier has also proposed the following method for the approximative determination oj the phosphoric acid by the volume of tlie tripU phospJiate jn'ecipitate obtained. It gives very fair resvUts and is easy of application : — If the urine is not acid add a few drops of nitric acid, in order to dissolve up any precipitated phosphates. Into a gi-aduated cylinder pour 50 c.c. of the urine, and saturate it with a solution containing fculphate of magnesia (1), ammonium chloride (1), ammonia (1), and THE PHOSPHATES. 409 distilled water (4). Shake well r.iid lay aside for 24 hours. All the |)hosphoric acid is precipitated as triple phosphate. The precipitate settles, and its height is to be read off in the graduated cylinder. 1 CO. of the precipitate cori-esponds pretty closely to 0*30 gram phos- phoric aciensator then turned till the two halves of the double plate are again coloured alike, or till the same teinte de passage is obtained as existed before the urine was inserted between the prisms. The zero of the vernier is now on the left side of the zero of the scale. Read off the number 510 EXCRETA: THE F.ECES AND VRINE. of divisions ; each division corresponds to one gram albnmin for 100 CO. urine, and each division of the vernier representing -^^ gram. If a decimetre tube is used instead, then multiply by 2 the degrees of the sciile and vernier. More correctly the percentage will be found by the formula — j;=56— ^^=the weight of substance in 100 c.c, urine. si s=the specific rotatory power. Z=the length of tube. «=indication of the scale. 3. Esbach's Method of Deposits. — The reagent employed is p)-epared by mixing 950 c.c. of a solution of picric acid containing 10 grams in the litre with 50 c c. acetic acid (sp. gr. 1007) ; shake Avell and lay aside. Specially prepared tubes of glass about 6 inches high, 0"6 inch wide, and graduated in grammes, are required. There are two marks engraved on each tube, and up to the level of the lower mark it is to be filled with the urine, and up to the higher mark with the reagent. Process. — If the urine has a higher sp. gravity than 1006 to 1008, dilute it, noting the amount of water required, and if it is not acid add a few drops of acetic acid and stir well. Then fill the graduated tube with the urine and the reagent as just described ; close the tube with the finger and turn it upside down several times, so as to mix the two fluids. The tube is next to be laid aside for 12 hoiu'S and the level of the deposit of albumin read off, which will give the number of grams of albumin present. If the urine has been diluted on account of its density, of course this ndtust be taken into consideration. For clinical puiposes the indications are sufficiently exact, as I have found by comparison with Scherer's gravimetric method. It is also very easy of application. 4. Rourjh Clinical Method of Deposits. — As a means of compari- son as to the relative amount of alljumin discharged fiom day to day, the ready method is fiequently adopted of boiling daily in the same sized test tube the same amount of urine passed about the same hour of the day, and then adding 3 or 4 drops of acetic acid ; the tube is laid asifle, and the height of the deposit as compared with the volume of the urine noted ; or, if no deposit, the degree of opalescence or cloudiness. Oidy by u.sing urine secreted as nearly as possible under similar conditions as to time, &c., testing equal amounts, boiling for a definite time, and noting the height of the deposit after a certain ABNORMAL CONSTITUENTS. CI] period has elapsed, caw any even widely apjjroximative results be obtained. 5. Roberts's D'dulion Method. — When an albuminous urine is progressively diluted with water and tested at frecjuent intervals with nitric acid after Heller's method, it will be noticed that the result- ing precipitate or opacity becomes less and less, until at last it vanishes; when this happens less than 00014 per cent, albumin is present. With the increasing dilution the opacity also takes a longer time in appearing. Acting on this Dr. Roberts dilutes the urine until it gives no opalescence fur 30 seconds after the addition of the acid, btit shoivs it at the ioth second. The urine is first tested in the ordinary way, so as to form an estimate of the albumin present. It is then diluted 10 to 100 times, as deemed necessary, and a test tube about ^ inch wide is filled to the depth of an inch or so with the diluted fluid. With a pipette a definite quantity of nitiic acid (about 10 to 12 minims) is next allowed to flow into the obliquely inclined test tube, so as to form a layer below the urine a qviarter of an inch deep. The time of the addition of the acid should be exactly noted, and also the time in which the opacity appears, which may be more readily seen by hold- ing up the test tube to the light against some dark background. The experiment should be repeated with more or less diluted urine until the reaction appears in not sooner than 35 and not later than 45 seconds after the addition of the acid. The degi'ee of dilution is then noted. If, say, to arrive at this result, 5 c.c have been diluted up to 500 c.c. the urine is considered as having 100 degrees of alljumin, each degree corresponding to 0*0034 per cent. [0 008 (MuscuLus), 0*0033 (Ham.marsten)] ; and each volume of water required to be added being termed a degree, the zero being the state of dilution necessary for the terminal reaction. 6. Bodeker's Method : Prcci]ntatio7i with a Standard Solution of Acetic Acid and Potassic Ferrocyanide. — This gives fairly approxima- tive results when the albumin is not less than 1 to 2 per cent. The precipitation occurs in tlie proportion of 211 of the ferrocyanide to 1,612 albumin. Dissolve 1309 gram pure ferrocyanide in 1 litre distilled water : 1 c.c. = 0*01 gram albumin. Process. — Mix 50 c.c. of the albuminous urine with 50 c.c. ordi- nary acetic acid, and transfer the mixture to a burette. Five or six small filters are placed in as many funnels, and after having been moistened mth a little acetic acid are filled with boiling water. Now measure 10 c.c. ferrocyanide solution into a beaker, and add to it 10 c.c. of the mixture of urine and acetic acid; shake well and filter ; test the filtrate, if bright clear and yellow, with a drop of uiine 512 EXCRETA: THE F.ECES AND URINE. and note if any cloudiness is produced. If the filtrate is turbid, and gives an increased turbidity on the addition of the ferrocyanide, then the albumin has not been all precipitated. The experiment is then to be lepeated with more or less of the ferrocyanide, according to the lesult of the first experiment ; and this is continued until a neai'ly exact result is obtained. 7. Tanret's method is founded on the precipitation of albumin by potassio-mercuric iodide in presence of acetic acid. It is thus prepared : — Grams Potassic iodide . 3-32 Mercuric chloride . . 1-35 Water . . 64-0 Acetic acid . 20 c.c. 1 c.c. of this precipitates yV^h of a gram of albumin. It is to be added carefullj' and slowly till all jjrecipitation is completed, which can be determined by allowing the precipitate to settle and adding a drop of the reagent to the supernatant liquid or to a few drops of the filtrate. CHAPTER XX. PATHOLOGY OF ALBUMINURIA. The cases in which albuminuria appears are very numerous. 1. Renal Affections. — In a great number of the cases of albuminuria the kidneys have undergone stmxtural alteration. Langhans and others have detected changes in the epithelium of the iSIalpighian capsules ; lesions of the epithelial lining of the tubes also frequently occur, but degeneration of this epithelium as well as casts in the tubes may be present without any con- sequent albuminuria (Schachowa). It is probable that amyloid degeneration of the kidney not involving the capsules may exist for a long time without any albumin in the urine (LiTTEN). Albuminuria may therefore be the direct conse- quence of renal disease, as in acute inflanvi nation or con- f/estion and in the different forms of Brighfs disease of the kidneys. As a temporary phenomenon it may be noted in the congestion often resulting upon paralysis of the vasomotor nerves of the kidneys, and occasionally recurring in specific and inflammatory fevers, Rttem\('(] with :i high temperatuie, PATJIOLOGY OF ALBUMINURIA. 513 as in scarlatina in an early stage, and during convalescence in typhus, typhoid, variola, erysipelas, and diphtheria ; and in meningitis, pneumonia, peritonitis, acute rheumatism, espe- cially when accompanied by pericarditis, pneumonia, or pleu- risy ; and in puerperal fever, particularly when attended with puerperal convulsions. If the temperature should continue high for some time (above 104° F.) peptones may also be pre- sent. In some individuals there is a great tendency to this occurrence of albuminuria in the course of different febrile attacks ; but albuminuria is a recognised sequela of scarlatina, and a frequent occurrence in variola, typhoid, erysipelas, ma- lignant pustule, and diphtheria. The congestion of the kidneys leading to the presence of albumin in the urine may also result from the irritation of powerfid diuretics, cantbarides, carbolic acid, &c. Ketention of the urine through closure of the ureters may likewise lead to allnuninuria, the epithelium lining the tubules becoming granular and fatty, casts also sometiines presenting themselves. Occasionally in advanced and unfavourable cases of diabetes albuminuria may set in. 2. A Dhtiirhance of the. Renal Ciroalatlon produced hy an Extrarenal Cause, leading to Redaction or Increase of the Blood Pressure in the Kidneys. — Diminished blood pressure in the glomeruli, as when brought about by pressure on the arteries, may cause albininnuria (IvUXE15EKg); but the experiments of GoTTWALT would make it appear that the higher the arterial pressure the greater should be the percentage of albumin. As LuDWiG has pointed out, ligature or compression of the renal veins causes a great swelling up of the venous bundles in the marginal layer of the medulla of the kidney, which leads to a closure of the urinary tubules in the neighbourhood. The disturbed circulation in the kidney may be produced by (a) compression of the renal veins by tumours or otherwise, or occlusion of these veins or of the vena cava ascendens by thrombi or emboli, or by an enlarged pregnant uterus (7th to 8th month, but occasionally in the 3rd or 4th month, 1 in 56 -Arsdale) ; (6) temporary compression of the renal artery ; (c) increased arterial blood pressure in one kidney, caused by extirpation of the other or by compression of the aorta btloiv L L 614 EXCRETA: THE F.ECES AND URINE. the origin of the renal vessels; {d) compression of the aorta above the origin of the renal vessels (Overbeck) ; (e) inter- ference with the circulation from distension of the heart ; ( f) compression of the bronchi leading to convulsions, weaken- ing of the cardiac beat, and suffocation ; ((/) great reduction of temperature (Lassar) ; (A) reduction of blood pressure, the quantity of the urine being at the same time diminished, as in cholera, in new-born children, in eclampsia parturientium, and occasionally in cases of epilepsy, tetanus, lead colic, and in many cases of chronic bronchitis, croupous pneumonia, j)hthisis pulmonalis, emphysema, pleurisy, and peritonitis : in many of these cases it would be difficult to state the true pathological cause and to say whether the renal pressure is reduced or raised. The congestion of the kidney may be active, as in the tem- porary tvu'gescence of the renal capillaries occasionally occurring in inflammatory and other fevers, after exposure to cold, in some forms of nerve irritation, and consequent on the passage of irritants through the kidneys ; or 'passive and secondary to general venous engorgement of the kidneys, as in the venous obstruction resulting from cardiac, pulmonary, and hepatic disease, and in thoracic aneurism and mediastinal, ovarian, and other tumours. 3. Disturbed Innervation. — Bernard found that lesions of different parts of the brain and spinal cord, as well as stimu- lation of the renal nerve S; caused an appearance of albumin in the urine, the results being probably due to the alteration in the diameter of the blood vessels and in the blood pressure. In some nervous diseases the nervous symptoms may be asso- ciated with the renal disease, as in the hemiplegia resulting from cerebral haemorrhage in contracted kindey with cardiac hypertrophy ; or it may be a direct effect of the nervous disease itself, as in the temporary albuminuria occasionally observed after epileptic or other nervous fits, or in tumour of the brain or other cerebral lesions, as meningitis, tetanus, and delirium tremens (Huppert, FUrstner, &c.) 4. Alteration in the Gonstitution of the Blood, brought about possibly by certain modifications in the tissue meta- morphoses occurring in different febrile and inflammatory affections, as in a liydriemic condition of the blood with atony PATHOLOGY OF ALBUMINURIA. 615 of the tissues, as occurs in purpura, scurvy, pyemia, or after exhaustive illnesses and extensive alteration of important organs. — The injection of diluted and filtered white of Qgg into the veins of an animal is followed by its excretion by the kidneys ; a siniilar injection of much water often leads to the same result. Want of common salt in the food, and an excess of a diet rich in albumin, especially after fasting, may also be succeeded by albuminuria, and occasionally in nursing women after sudden suppression of the secretion of milk albumin may appear in the urine. Certain poisons may likewise lead to albumin in the urine, as the long-continued use of large doses of morphia, after deep chloroform narcosis, and the inhalation of arseniuretted hydrogen. and carbonic oxide, &c., and in lead and phosphorus poisoning. The albuminuria occurring in cholera may depend on the in- creased sp. gravity of the blood resulting from the profuse alvine discharges. In many chronic and constitutional atFections albuminuria may be noted, as in leukaemia, syphilis, cancer, scrofulous sup- purations, &c., occasionally also in cases of chronic indigestion with constant alkaline urine or oxalate of lime deposits. 5. Admixture of Blood, Pus, or Semen "with, the urine may render it albuminous. The blood and pus may be derived from the kidney or the urinary passages, bladder, &c. Look for blood or pus corpuscles, sj^ermatozoa, threads of fibrin, and haemoglobin. When a purulent urine is treated with liquor potassge the deposit is rendered glairy or gelatinous. Diagnosis. — It will readily be seen that in many of these cases the albuminuria is only temporar^y, as in zymotic diseases when there is a specific poison and a higli temperature, and often in the course of such diseases as tubercle, cancer, and necrosis, &c. In all cases of albuminuria it should accordingly be care- fully noted whether or not the condition is a temporary or per- manent one ; an estimate should then be formed as to its amount ; concurrent evidence should also be looked for, and note taken as to the quantity of the urine, its sp. gravity, the presence in it of renal epithelium, tube casts, blood, pus. crystalline deposits, parasites, &c. 61 G 2-XCliJSrA : THE F.ECE8 AND UlilAE. Above all the student must not conclude, luhen he finds albumin in the urine, that its lovesence there is necessarily due to renal disease. A large amount of albumin in the 24 hours points to renal disease, and this is more likely to be the case if the urine is pale in colour and of low sp. gx. (under 1012), and about 3 or 4 pints in quantity. As a rule a small amount of albumin and a dense and high-coloured urine point to pyrexia, or to some interference with the renal circulation. Casts or renal epithe- lium are indicative of renal mischief. Therefore, if the urine is peiTnanently albuminous, casts and renal epithelium present, and no other abnormal condition capable of producing the albuminuria to be detected, the probability is that the disease is renal. It is of importance also in cases of albuminuria to deter- mine the amount of urea passed, as the prognosis would, as a rule, be much more unfavourable if the excretion of this body fell considerably below the normal. CHAPTER XXI. HJUMATURIA—BLOOI) IX THE URINE. Blood is present in the urine in many diseases, the corpuscles and haemoglobin, or in some cases the haemoglobin alone. Fibrin or the fibrin generators may show themselves, in which case spontaneous coagulation would set in ; but this is a very rare occurrence except in tropical countries. Properties, — Urine containing blood, unless the amount is very slight, is either of a blood red or brownish colour with a black, smoky, or greenish tint, and generally deposits a red or reddish brown sediment after standing. If the source of blood is other than the kidneys, as the ureters, bladder, or urethra, the colour is of a brighter red, and clots are often present. Tests. — 1. Presence of Blood Corpuscles, Casts, Renal Cells, &c. — When ])loo(l is suspected to be present the urine should be allowed to stand at rest for some time, to allow a ILEMATURIA— BLOOD IN THE URIXE. h\l deposit to be formed. The viicroscope detects blood corpuscles that may be almost unaltered, or much swollen, decolourised, and deformed ; also blood and fibrin casts. At times micro- scopic examination fails to detect the corpuscles, on account of the changes they have undergone ; recourse must then be had to the other tests. Much alteration in the corpuscles is likely to occur when the urine is ammoniacal or of very low sp. gravity ; otherwise, with the exception of some decolourisation, they may retain their form for several days, and appear as cir- cular, non-nucleated, somewhat flattened disks, which must not be confounded with sporules, discoid crystals of oxalate of lime, or renal epithelium. In cases of doubt, after examining the deposit upon a elide with the microscope, irrigate it with a strong watery solution of magenta (about 1 per cent.), which stains the nuclei of the renal epithelial cells and also the sporules ; and irrigate in the same way another specimen with a solution of eosin (eosin 1, alum 1, alcohol 100), which imparts a rosy orange tint to the coloured corpuscles, if they have not been completely deprived of their hgemoglobin. When the presence of the corpuscles has been satisfactorily established, it should be noted whether the blood is associated with calculi, parasites, or much mucus ; and at the same time the obser- vation carefully made whether or not the blood is intimately mixed with the urine, and blood, fibrin, or epithelial casts, or pus or cancer cells present. 2. Presence of Hcemoglobin.— The urine, according to HOPPE Seyler, seldom contains oxyhaemoglobin, but instead methaemoglobin ; with pathological urine containing blood, how- ever, I have generally been able to obtain the absorption bands of oxyhgemoglobin, and sometimes that of the so-called methoemofflobin as well. The unfiltered urine should be examined directly. (a) A layer of the urine is examined in a small glass vessel with parallel walls, the narrow slit of the spectroscope being brought into close proximity with it. Sometimes only the band near d is visible. (b) If no absorption bands are seen add acetate of lead in excess to a considerable volume of the urine, filter, and shake up the precipitate thus obtained in a little water, where it is to 518 EXCRETA: THE F.ECES AND URINE be decomposed with sodic carbonate, then tlie precipitated lead carbonate removed by filtration, and the filtrate examined spectroscopically (Hoppe Seyler). (c) Mix in a test tube equal volumes of spirits of turpen- tine and tincture of guaiacum, freshly prepared by dissolving in alcohol (83 per cent.) small fragments detached from the interior of a large piece of the gum that has been broken in two. Shake this tincture and the spirits of turpentine well together, so as to form an emulsion ; and add a little of the mixture to some of the urine in a test glass, pouring it slowly down the side of the tube upon the urine : if blood is present the resinous precipitate lias more or less of a blue coloration (Almex). Or the test may be thus made : Place a few drops of the urine in a test tube, add a drop of freshly prepared tincture of guaiacum, then a little ozonic ether, and shake well. If the ether rises to the surface of a blue colour, blood is present. 3. Presence of Hcematin. — (a) The urine is rendered strongly alkaline with caustic soda and boiled : the precipitated phosphates will be coloured of a blood red by the contained hfC matin. A somewhat similar reaction may be obtained with urine containing chrysophanic acid or the pigments of rhubarb or senna ; but the deposit, when treated with caustic potash, is not dichroic ; and mineral acids, instead of brightening the colour, as is the case with blood, render it less vivid. (6) Acidulate the urine containing the blood with acetic acid and boil it, when a brownish coagulam of albumin and ha;raatin is precipitated. Decant the urine from the coagulum, and having washed the latter with a little water, shake it up with some alcohol containing sulphuric acid : a red or reddish brown solution is thus obtained, which is to be filtered. If sufficiently concentrated it will show on spectroscopic examina- tion a dark band midway between c and D, and another lighter and less decidedly marked but broader band extending from midway between d and e to F. Sometimes, however, with a certain degree of dilution this latter band may appear as two, one near F and the other near d. If now the alcoholic solution is evaporated to dryness and the residue incinerated, ILEMATUlilA—nLOOn IX Till: I/L-IXK r,iu the presence of iron in the ash may be detected by dissolving it in a few drops of dilute hydrochloric acid, and adding a little ferrocyanide of potassium, when a blue precipitate is formed. This is best effected on a slide under the microscope. 4. Presence of JItemin. — (a) By adding a few grains of chloride of sodium to the alcoholic solution obtained as in the last process, and evaporating it carefully, hflemin may be formed. (6) Render the urine alkaline with ammonia or potash, then add some solution of tannic acid, and acidify with acetic acid. A dark precipitate is obtained, which is to be collected and washed on a filter, dried, and a little of it rubbed up in an agate mortar with a trace of sodic chloride, and then transferred to a test tube to which some glacial acetic acid is added, and the whole boiled ; next filter into a watch glass, and dry the filtrate at a moderate temperature. Now heat the residue on a glass slide with some drops of glacial acetic acid, and having applied a cover glass heat again after the addition of more acetic acid; when cool examine under the microscope, and if blood has been present in the urine dark brown rhombic lamellae of hgemin or flattened rhombic needles frequently crossed are to be seen (Sthuve). To Distinguish hetiveen Hoematiiria and Albuminuria. — Bloody urine necessarily also contains albumin ; hence it is often of importance to know, when blood is found in the urine, whether the whole of the albumin present comes from this source — whether, in short, the case is hsematuria plus albu- minuria or ha^maturia alone. This can be ascertained by com- pletely separating all the albumin from a definite volume of the urine, weighing it after it has been dried, and then incinerat- ing and determining the iron present in the ash, from which the corresponding quantity of blood can be calculated. Pathology. — The presence of blood in the mine indicates a hpemorrhage fi"om some part of the uroi)oietic tract. Its causes and consequences vary gi-eatly. It sliould be carefully noted "whether or not the condition is permanent or temporary, in the former the prognosis being very unfavourable, as in cases of intense scurvy, septic fevers, »tc. Sources. 1. Kidneys. — Calculi, tubercle, cancer, or abscesses; in acute and occasionally in chronic forms of nephritis; aneurism and 5-20 EXCRETA: THE F-ECES AND UlilNE. emboli of the renal arteries, and thrombosis of the i-enal veins ; falls and blows leading to rupture ; parasites in the mvicous membrane of the pelvis, as in the endemic hfematuria of hot climates, and in some cases of pyelitis ; in the congestions at times occurring in the eruptive fevers, in which it may occur from the whole urinary tract; or as the result of exposure to cold, or after the use of cantharides, turjientine, and other powerful diuretics ; occasionally also in a paroxysmal form, and in the hsemorrhagic diathesis often noted in scurvy, purpura hsemorrhagica, and malaria, 2. Bladder. — Diphtheritic and acute cj^stitis, calculi, carcinoma, congestion, fungoid growth, varicose veins, &c. 3. Prostate. — Structural disease. 4. Urethra. — After catheterisation, kc. Hsemoglobinuria. — Urine containing ligemoglobin without any blood coipuscles is of a very dark red colour, coagulating on boiling and a brown scum forming on the surface. If it is now well shaken up with alcohol containing sulphuric acid the haemoglobin is dissolved, and the alcoholic extract gives the absorption spectrum. This would point to haemoglobin existing free in the sertim of the blood, owing to a considerable destruc- tion of the corpuscles in the blood vessels; and, indeed, it is possibly owing to the excess of haemoglobin set free that it is excreted in the kidneys, for a small amount of this body is constantly being liberated under normal conditions. That this is very probable is shown by the result of experiments in which, when only small quantities of haemoglobin were injected into the blood, no elimination of it occurred, whilst the injection of large quantities produced haemoglobin uria (Ponfik). This condition has been noticed after ingestion of excess of arseniuretted hydrogen, hydrochloric, phosphoric, lactic, sulphuric, and pyrogallic acids, and potassic chlorate and sodic bicarbonate ; also at times after jaundice, fat emboli, burns, typhoid fever, scarlatina, scurvy, putrid fevers, pernicious inter- mittent, transfusion of lamb's blood, &c. ; and it has even appeared after long-continued cold baths and severe exercise. 3IethcKmoglohin is said to be frequently found in urine, appearing if much destruction of the coloured corpuscles is induced in any way, as by injection f)f wat^ pints in the twenty-four hours, but it varies generally between 8 and 15 pints, although it may be much greater. The occurrence of fevers or inflammations diminishes it greatly. 4 per cent, is the average amount of sugar present, rarely rising much above this, but it may form 12 per cent. Sugar of milk may be found in the urine when the secre- tion of milk or its discharge is suddenly arrested ; this is a regular occurrence 24 to 48 hours after weaning. An acetone body is also occasionally present in diabetic urine, which gives a brownish red coloration with ferric chloride ; such patients frequently emit an odour of acetone in the breath. Tests. 1. Tro.m.mer's. —Add to the urine one-fourth to one- third its volume of caustic soda solution, then drop by drop a solution of cupric sulphate (1 : 10) until the precipitate formed appears to have dissolved completely ; heat the upper third of the mixture in the test tube, and a yellowish red jjrecijjitate is formed before the boiling point is reached. Or apply the test by dropping the urine slowly into a little boiling diluted Fehling's solution until rather less than an equal volume of the urine has been added. If very little sugar is pre- sent 5 to 20 minutes may elapse before the suboxide is deposited ; the boiling, however, is not to be prolonged. But a milky ap- pearance is very suspicious, and generally indicates sugar. SUGAR IX THE UliiyE. 523 Uric acid, hypoxanthin, and mucus, &c., possess a reducing action on cupric oxide ; the reduction also by sugar is more or less hindered by the presence of albuminous bodies, peptone, pepsin, kreatin, kreatinin, and to a less degree by the urinary pigments in excess. Sometimes the reaction fails unless the urine is diluted before being tested (Kulz). The presence of reducing agents in the urine other than sugar may give rise to a strong yellow coloration after the urine has been boiled with the cupric oxide and set aside for a few minutes. In case of doubt lay aside a similar mixture in the cold for twenty- four hours, and the sub- oxide will separate if sugar is present. Or, where there is very little sugar present and some doubt as to the cause of the reduction of the cupric oxide, the urine may be precipitated with plumbic acetate and the filtrate tested with the Fehling's solution. If there is very little sugar it is advisable to filter the urine through animal charcoal several times, and the resulting lim})id filtrate will give the sugar reactions more sharply, although a little of the sugar is retained by the charcoal (Seegen). 2. Ciixular Polarisation. — A urine containing even 0"3 per cent, sugar will give a marked polarisation to the right. Diabetic urine is generally sufficiently clear for the purpose ; but if too highly coloured it should be filtered through animal charcoal, although charcoal is not to be highly recommended, as it holds back some of the sugar ; better therefore to precipitate the colouring matter with neutral lead acetate, and to pass the urine through an unmoistened filter into a dry beaker. If albumin is present it must be separated, as it polarises the light differently to sugar — that is, to the left. Take 100 c.c. urine, add a drop or two of acetic acid, and boil for some time ; filter and wash the precipitate with water until the filtrate occupies exactly 100 c.c. When cold test with the polariscope. The use of chloral and of certain aromatic bodies interferes with this process, on account of their presence in the urine causing polarisation to the left. 3. Fermentation Test. — Add a little washed yeast to a long, narrow, closed tube, then fill this up with the urine and invert over water or mercury. Lay aside for 12 hours in a moderately 624 EXCRETA: THE FMCES AND URINE. warm place, and then note tlie accumulation of gas in the tube and the consequent displacement of the urine. The gas may be shown to be carbonic acid by its extinguishing a burning taper when dipped in it, and by forming an opalescent fluid when shaken up with lime water. 4. Bismuth Test. — According to Bottger no other body present in urine except sugar reduces the bismuth salt. Make a solution of carbonate of soda (1 to 3 water) ; mix a little of this and the urine in equal volumes, and then add a pinch of basic bismuthic nitrate ; now boil for a few minutes : the presence of sugar is shown by the bismuthic salt becoming reduced and a greyish or blackish deposit or coloration produced (see p. 65). If much pigment or albumin is present separate the latter by acidifying with acetic acid and boiling, and the former by filtration through animal charcoal. 5. When only traces of sugar are present Seegen's plan of repeatedly filtering the urine through animal charcoal until it is colourless, then washing the charcoal with a little distilled water, and testing the washings with a little Fehling's solution, may be adopted with advantage. 6. In case of doubt, and if we wish positive proof of the presence of sugar, filter the urine through animal charcoal and evaporate to a syrup ; digest the residue with alcohol (82 per cent.), evaporate the alcoholic solution, and apply Trommer's test to the residue dissolved in water* Test also the washings of the charcoal as above. 7. Toruke are developed in diabetic urine, the yeast fungus and the penicillium glaucum. A white scum, due to these bodies and liighly characteristic of the presence of sugar, soon accumulates on the surface. They generally occur as minute oval vesicles that change their shape by growing and developing new vesicles. 8. Clinical Method (Pkatesi, after Koj{SI.ey).— Dissolve caustic potash 2*5 grains in (JO grams very concentrated li(iuid potassic silicate, and then add 2 grams potassic bichromate. Preserve this solution in a well-str)ppored bottle. Now fut a piece of lin iulo slri|)s :ili<»iij, three iiK^hos long and a liHle more than oiie-lhinl inch \\i(h'. W'ilh a glass rod place a drop SUGAR IN THE URINE. 526 of the above solution on tlit; end of one of tlie sdip.s of tin and dry it there at a gentle heat ; two, three, or more drops are also to be dried at the same spot. To test for sugar one of these prepared slips is to be taken and the deposit heated, when it swells up and takes a canary-yellow colour. Drops of the urine are now to be placed over the yellow deposit one at a time, heating after each addition, so as to evaporate almost to complete dryness. If sugar is present and in a proportion not less than 0'4 or O'o per cent., a green coloration shows itself, owing to the reduction of the chromate by the deconip)osition products of the sugar. 9. Picric Acid Test. — Add to the urine an equal volume of a saturated watery solution of picric acid, and after the sub- sequent addition of a little caustic potash heat gently, when a 'inarhed reddish hrotcn coloration w411 show itself. Tliis change of colour is due to the formation of picramic acid. By means of this colour test Dr. G. Johnson makes a quantitative estimation of the suirai- present in a diabttic urine. A standard of coaiparison is tirst prepared by adding to a lon^' test tube one drachm of a solution of gr;qio sugar containing one grain to tlie Huid ounce, half a drachm of liquor pntas!-te (B. P.), ten drops of a satui-ated eolu- tion of picric acid, and distilled water uj) to half an ounce ; this mix- ture is then raised to boiling point, and the boiling continued for a miniite. A claret red colour is developed, and its depth of tint indi- cates a quaiter grain of sugar to the fluid ounce. But, as the tint becomes paler after a few hours, it is advisable to imitate it by addin^ acetic acid to a solution of ferric chloride, and to enclose the resulting fluid in a stoppered bottle, so as to serve as a permanent standard of comparison. The process consists in boiling for a minute a mixture of a drachm of the saccharine urine, half a drachm of liquor potasste, and twenty drops of a saturated solution of picric acid, the whole being made up to half an ounce with distilled water. According to the amoxint of sugar present will be the intensity of colour produced. Two small vertically arranged tubes are now to be placed in a good licLt on white papsr ; into one of them is poured some of the standard of comparison, and into the other the more or less diluted coloured solution obtained by boiling the urine as above with the picric acid and potash. The dilution is to be made in a graduated tube, and it is to be repeated until equal columns of the diluted solution and of the standard of comparison exhibit the same tint when examined 52G EXCTxETA : THE F.ECE.S AND URINE. vertically in a good light. After each comparison the coloured urine uiiist be returned to the graduated tube in which the dilution is effected, until the process is completed ; and from the amount of dilu- tion required the proportion of sugar present is calculated. To Separate the Sugar from the Urine. — Evaporate the urine to a syrupy consistence and let it stand aside, when after a time yellow, friable masses of sugar will crystallise out— a process that may be favoured by treating the syrup with ether and then letting it evaporate. Digest the residue with al)solute alcohol to remove the urea and extractives, and separate any sodic chloride present by dissolving the crystals of sugar in water and precipitating with sulphate of silver ; then filter, evaporate, and digest the residue with spirit to dissolve up the sugar. Quantitative Istimation. I. />'// Feiiling's Method. — See p. 75. The method has thus been modified and greatly simplified by Dr. DunoJiME : Two small pipettes, graduated to deliver 1 and 2 c.c. respectively, are required, as well as two or three test tubes. A pre- liminary experiment is first required to ascertain the number of drops in a c.c. of the urine to be tested : this is readily effected by drawing up a c.c. of the urine into the graduated pipette and then allowing it to escape in drops. 2 c.c. of Fehling's solution are diluted in a test tube with an equal volume of liquor soda3 and boiled. Titiation is next performed with the diluted urine as in Fehling's process. The number of drops found to be contained in 1 c.c. of the urine multiplied by ten, and the product divided by the number of drops of the urine required in the titration, equals the amount of glucose per litre in grams. II. Ji// Circular Polarisation. — Fill the two-decimetre tube of the polariscope with the filtered urine, and having rendered the tint alike in both halves of the double i)late, read upon the scale and vernier the deviation in degrees. When the two-decimetre tube is used the percentage in grams is obtained by dividing the number of dcrees by 2, while with the one-docimetre tube the number of degrees represents directly the percentage of sugar in the urine. (For full details of the process see p. 70.) If alhurain is present it must first be removed by adding a drop or two of acetic acid and boiling some time, or before boiling adding an equal volume of saturated sodic sulphate solution in addition to the acetic acid ; the filtrate is ready for testing. The estimations by circular polarisation do not always agree with those obtained by FEHMN(i's method, which is due pi(jl>;ibly to the piesence of other Ijodies allied to sugar. SUGAR IN 'HIE UlilXF. r>27 III. Aj'proxiniative Estimation from the Deiisitij (Bouciiardat). — Having ascertjiined the presence of sugar, determine the density of the urine exactly with a urinomcter, and ascertain how much is passed in the 24- hours ; or it is better to collect the whole urine passed in that time, and take the density of this. Suppose the total amount to be 4 litres, and the density at 15° = 103G. An approximation to the amount of solids in urine is obtained (sec p. 412) by multiply- ing 36 by 2, and for 4 litres this would be 3G x 2 x 4 = 288 grams solids; and taking 50 grams as the average weight of solids of healthy urine, 288 — 50 = 238 grams of sugar would accordingly be present in the 4 litres passed in the 24 hour^. As, however, the urea as well as some of the other urinary constituents are also greatly in- creased in diabetes, this estimation can only be regarded as a very rough approximation. If in the determination of the density the temperature of the urine is above or below 15° (for which temperature the urinometer is generally gr:)duated) a correction must be made as follows ; — Subtract fi" om tlic degree Ol) .linpil Ada to the degree obtained Temp. Temp. 0°1O.o° . i:5 14° . 02 6° . 1-2 l(i° . 0-2 7° . 11 17°. 0-4 8° lo 18° . or, 'y ()-9 T.)° . OS 10° ()-8 20° . 1-0 11° 0-7 21°. 1-2 12° . OC 22° . 1-4 13° . 0-4 23° . 24° 25° . l-fi ID 2-2 This method serves better when there is an abundant secretion of urine rather than when it is comparatively scanty. Pathology. — When sugar has been detected with certainty in the urine the next important step is to ascertain if its 'presence there is only temporary or if it is constant ; then it is desirable to find out the amount daily excreted and also the quantity of fluid discharged. Permanent glycosuria constitutes diabetes mellitus. In this disease not only is sugar present in the urine, and occasion- ally in the sweat and other secretions, but there is generally also an increased discharge of water, urea, and phosphates, the fixed salts like sodium chloride and the like being generally 528 EXCRETA: THE F.ECES AND URINE. diminished, while less carbonic anhydride is expired and less oxygen absorbed than in health (Voit). While heredity seems to be a prominent factor, mental distress, an excessively saccha- rine diet, and gout appear to act as determining causes. In many cases where the quantity of urine passed is small there is abundant perspiration. A diminution in the amount of sugar often coincides with an increase in the phosphates and oxalates. The albumin sometimes present in the urine is frequently an evidence of renal disease (Rayer), its amount often having been observed to be related inversely to that of the sugar (ScHMiTz). The muscular weakness that is often present is said to be due to a general alteration in the muscular fibres, extendino- even to the cardiac muscle. Death may therefore be due not only to diabetic coma and acetonajmici, but also to cardiac weakness. Transitory glycosuria, on the other hand, may show itself in the early stages of tetanus, cerebrospinal meningitis, cases of cerebral apoplexy, tumours of the medulla oblongata and of the pia mater, particularly in the fourth ventricle ; in chronic inflammatory changes in the calamus scriptorius, carcinoma of the pituitary gland, cerebral softening and atrophy of the grey substance ; in myelitis, general paralysis, and sometimes after epileptic fits or direct injury by blows or shocks to the brain and sympathetic, and occasionally after over-work; in some heart and lung affections, as pneumonia and phthisis, after paroxysms of whooping cough and spasmodic aslhma; occasion- ally in cirrhosis of the liver, as a result of different disturbances of the abdominal circulation, and frequently when the secretion of the mammary glands is hindered (Sin^ty) ; at times also when carbuncles are present, and in the urine of pregnancy, cholera, intermittent fever, gout, and Bright's disease. Artificial Production of Diabetes — The appearance of sugar in the urine can be brought about by puncturing the medulla ol)]ongata in the vasomotor area, a little above the point of the calamus scrip- torius and behind the corpora quadrigemina, but for this to be success- ful the olivary fasciculi should be injured (Bernard). The same result can also be produced by puncturing other parts of the nerve centres, as by desti-oying the spinal cord at the oiigin of the bradiial nerves and opposite thr- second dorsal vertt^bia (Sc'IIIFf), by division of the sympathetic in the thorax ; also by inq>i.Hliiig the respiration SUGAR ly THE URINE. 520 (Pavy), or injecting diflorcnt bodies, such as dilute phosphoric acid, much 1 por cent, sodic chloride solution, inulin, or arterial blood (Pavy), into the portal vein. INIost of the injuries that are followed Ijy sugar in the urine ajipear to produce hypenemia of the liver. Further, sugar may appear in the urine after large doses of strychnine, morphia, curara, chloral, amyl nitrite, spirits of turpentine (Almkn), deep chloroform or ethei- narcosis, carbonic oxide poisoning, siibcutaneous injection of nitrobenzol or uitrotoluol, and coi)ious ingestion of lactic acid. In arsenical and phosphorus poisoning, although the liver becomes diseased and is said to contain no glycogen, yet sugar is found in the urine. Ligature of the bile ducts also causes the glycogen to disappear (Lego). Temporary glycosuria may likewise be induced by an alimentation too rich in starch and sugar, especially after long abstinence ; and this is more liable to occur with a diminished alkalinity of the })lood and an enfeebled respiration ; an injection of concentrated solution of sugar of milk into the stomach leads to the same result. The reducing body found in the urine in all these cases, however, may not always be sugar. The different cases given above of IraDsitory glycosuria may, from their nature and results, be classified into — 1. Temporary or incidental, as in those occurring after deep chloroform narcosis, after excessive ingestion of saccharine and amylaceous food, in asthma, epilepsy, and in the convalescence of cholera, &c. 2. More or less permanent, rs in true diabetes : (a) flow of urine increased, with abundance of sugar, and associated with thirst, debility, emaciation, &c. ; (6) sugar slight or consider- able, persistent or intermittent in its appearance, but without any serious attendant symptoms. Alkapt(»>. and ]>i/rocntfichiu are occasionally, V)ut larely, present in urine ; they give some of the same leactions as sugar, but they do not reply to the bismuth or fermentation tests. Alkapton is obtained by precipitating the urine with acetate of lead, filtering, precipitating the filtrate with basic lead acetate, and collecting the precipitate; this precipitate is washed, suspended in water, and decomposed with hydric sulphide ; the filtrate is evaporated to dryness and extracted with ether. It is a golden yellow, resinous body, very deliquescent, and soluble in water and spirit ; it becomes brown when exposed to the air, and the urine containing it may produce brown stairs on linen. -M M 530 EXCRETA: THE F.ECES AND URINE CHAPTER XXIII. BILIARY URINE. The biliary acids being generally in great part reabsorbed and disposed of in the blood under normal conditions, most pro- bably being chiefly oxidised to the state of carbonic acid and water, we can easily understand that obstruction to the escape of the bile produces a greater effect from the retention of the pigments, of which normally so much is excreted with the fteces, than from the retention of the biliary acids ; so that we may only expect to meet with them when there is a hyper- secretion of bile. But according to Dragendorff, Nauyn, and A^OGEL the biliary acids in minute proportion, as well as traces of the pigments, are normal constituents of ludne ; but they are often entirely absent (Hoppe Seyler, KiJLz). The amount of biliary acids excreted is very slight, for while Ranke calculated that about 10 grams are formed in the 24 hours, not more than one-third of a gram has been found in the urine passed in that time in cases of jaundice. Whether or not the biliary pigments are generally present is doubtful, but they are certainly occasionally present in the urine of healthy persons in summer time (Scherer) ; in jaundice they are a common constituent of the mine, while in intense forms of this disease they may be present in all the fluids of the body. Properties. —The urine is of a yellowish brown to a greenish tint, the colour becoming darker on exposure to the air ; it froths readily, and the froth is of a characteristic deep yellow colour. The ingestion of santonin and chrysophanic acid give a somewhat similar colour to the urine. Tests. A. The Biliary Acids. — The detection of the biliary acids is much more difficult than that of the pigments ; and the presence of much pigment, of oxidising substances, or of albumin, &c., interferes with Pettenkofer's reaction. 1. Pettenkofer's Test. — {a) Shake a little of the urine with a drop of syru]), and tlien allow the sulphuric acid to trickle down the side of the inclined test tube. Note the purple band at the up}>er margin of the acid. BILIARY URINE, 531 The sulphuric acid must not cor.tain sulphuious acid, and the temperature must not be allowed to rise much above 38° C. ; albiunin also must be separated if present. The presence of different essential oils may produce the same coloration (see p. 209). (1)) Dissolve a little cane sugar in the urine and dip into it a piece of filter paper, which is then removed and left to dr}'. A drop of strong sulphuric acid is added to this by means of a glass rod, and in a (juarter of a minute a violet red spot gene- rally shows itself. The method is delicate (Sthassiuirg). (c) The froth test may also be applied (Charles). See p. 202. 2. It is always advisable, in case of doul)!, to isolate the biliary acids before applying the tests. [a) HoppE Seyler tliiis proceeds : Precipitate the urine with acetate of lead and a little ammonia, wash the precipitate on a filter with water, and tlien, liaving boiled it with alcohol, filter hot. The hot alcohol dissolves the lead salts of the biliary acids. This hot filtrate is treated with some drops of carbonate of soda solution and evaporated to dryness over a water bath : the residue is extracted with boiling absolute alcohol ; this last extract is to be collected in a closed flask, and a little ether added, the alcoholic solution being first concentrated to a small volume if necessary. A resinous precipi- tate soon falls, which may become crystalline if allowed to stand long enough under ether, hut a solution of the resinous precipitate serves for the tests. [h) Another plan of isolation is Salkowski's. The urine is first evaporated and the residue extracted with spirit, the spirituous extract diluted, and the precipitate taken up again with absolute alcohol. By diluting the last alcoholic extiact a precipitate is again obtained, which is to be dissolved in water and treated with acetate of lead and a little ammonia, as in Hoppe Seyler's process. (o) Evaporate the urine, treat the residue with alcohol, and evaporate the alcoholic filtrate. A few drops of water are then rubbed up with the dried extract, and a solution of sugar in water (1 in 3) mixed with it. Strong sulphuric acid is next added drop by drop, and a purple colour will soon a]»pear, which, however, quickly fades. Too much water and a temperature above 60' interfere with the reaction. {d) Hoppe's 2Ie(hoiI. — Treat the suspected urine with excess of milk of lime and boil for half an hovir or so ; fiber, evaporate the >t M li 532 EXCRETA: THE F.ECES AND URINE. filtrate nearly to dryness, add excess of hydrocliloric acid, and boil f n- another half-hoar, adding fresh acid from time to time. Dilute ■when quite cold with five to six times its volume of water, filter, and wash the resinous mass obtained, which is then to be dissolved in absolute alcohol, treated with animal charcoal, again filtered, and the filtrate evaporated to dryness. Choloidic acid, a derivative of the biliary acids through cholic or cholalic acid, is thus obtained. It is dissolved in a little caustic soda and warm water, a drop or two of syrup added, and a few drops of sulphuric acid allowed to trickle slowly into the mixture : a dark violet colour is produced. B. The Biliary Pigments. — The urine must not be allowed to decompose before the examination for pigments is made ; otherwise hydrobilirubin may have replaced the bilirubin or biliverdin. 1. GtMELIN's Test, which depends on the play of colours produced by the oxidation of the pigment by means of nitric acid, can be performed after many methods. (r<) That commonly employed is to spread a few drops of the urine on a white plate, and then to bring a drop or two of yellow nitric acid in contact with the margin of the thin layer of urine or into its middle : the play of colours that appears at the ])oint of contact com- mences with green and ends with red and yellow. The nitric acid should contain a little nitrous acid, which is easily effected by heating it with a piece of stick or a fragment of sugar ; biit too much nitrous acid is to be avoided. {h) Pour some strong yellow nitric acid into a test tube, and let tlie urine trickle down the side of the tube upon it; a green band first appears at tha point of contact of the two fluids, which extends higher and higher, and is succeeded inferiorly by a blue, a reddish violet, and a yellow layer, and of these the green and the red are most character- istic (KDhne). (c) After filtering the uriiie pour the nitric acid over the inner side of the filter : the play of colours is well marked. If the filter is allowed to dry the reaction succeeds better. Merely dipping the filter psiper in the urine produces less intensity of colour (Rosenbach). (d) Mix the urine with very dilute nitric acid, and then let strong sulphuric acid run down the side of the test tube : the coloured rings .spread from the upper surface (Brucke). (e) Add a little albumin to the urine before the nitric acid : the albumin is precipitated of a dull green or bluish colour (Heller). (f) Tested with an alcoliolic solution of lu'omine (.5 per cent.) and BILIARY UliiyE. 533 with aqueous cliloric and iodic acids (20 per cent.), three stages of coloration are obtained — green, blue, and violet — after which there ensues a change of colour to reddish, yellow, and finally decoloration. Fallacies of Gmelin's Test. — The presence of alcohol and indican may give indications that are liable to be mistaken for those of bile, Init note that with indican only red and violet zones will show themselves, while with bilo pigment, unless the solution is very dilute, the zones are all present in the order already given, gi-een appearing first. To avoid any diffi- culty from indican add to a little of the urine some drops of a solution of potassic nitrite and a few drops of sulphuric acid : a beautiful green colour is produced by traces of bile; but the colour rapidly disappears, becoming yellow. 2. If a solution of violet of raethylan'diii is pom-ed into normal urine, a blue ring will be formed at the surface of the liquid, but if the urine is icteric the ring is of an intense carmine colour. This only occurs with icteric urine, and not with normal urine to which bile has been added, nor with urine containing other colouring princi})les (Paul). 3. Sometimes bile pigment may be present in urine, and yet not give the colour reaction ; this is more frequently the case with the urine of patients whose temperature has con- tinued high for some time (Peussak). In such urines we therefore require to separate the pigments before testing. This may be effected by one of the following processes, to one of which in cases of doubt it is advisable to have recourse, as by doing so we avoid any mistake from the presence of methae- moglobin, urobilin, or indican, &c. : — {a') Precipitate the urine with milk of lime and transfer a piece of the precipifcite, the size of half a hazel nut, to a test glass ; wash it here several times with water to remove any indican that may be present; then half fill the tube with absolute alcohol and render distinctly acid with dilute sulphuiic acid. It is next warmed and filtered, and on boiling the filtrate the biliary pigment will show itself by the appearance of a dark green to a blue coloration, though in some cases it remains yellow or greenish yellow (here choletelin only may be present (Heynsius), so we must acidify with hydrochloric acid and examine spectroscopically). The bilirubin is precipitated by the lime, from which combination it is liberated by the sulphuric acid, and is then dissolved up by the acidulated alchohol (Htppeht). 534 EXCRETA: THE F.ECES AND URINE. (6) HOPPE Seyler precipitates with milk of lime as above, but to eflect complete precipitation be passes a current of carbonic acid through tlie liquid. The precipitate is let stand several hours, then collected on a filter and shaken up in some water to which chloroform and acetic acid have been added. The chloroform solution is either yellow or green, according to the excess of bilirubin or of biiiverdin, and to it Gmelin's test can be applied. (c) Salkovvski proceeds thus : Render the urine alkaline with a little sodic carbonate, and add calcium chloride solution drop by drop and with rej^eated shaking nntil the supernatant liquid is of the colour of normal urine. Collect the gelatinous precipitate, wash it well, and having- transfei-red it to a small flask, cover it with alcohol, and dissolve it by shaking well with a little hydrochloric acid. On boiling the clear solution it will become of a green to a blue colour, changing to a Violet or red on the addition of nitric acid. ((?) The pigments may be precipitated with basic lead acetate, the precipitate decomposed with hydric sulphide, then washed with water, and the pigments finally extracted with chloroform. (e) An easy method, which succeeds often when the urine gives no evident reaction of biliary pigment, is to place the urine in a freezing mixture for some time until the ui-ates have separated, then to collect these on a filter and dissolve them in hot water ; this solution will give the characteristic pigment reaction. (f) Acidify a large quantity of the ui-ine with a little acetic acid, and then shake it up well with chloroform added a little at a time ; allow the urine to stand and decant the su2>ei-natant chloroform, which can bo used to extract fresh quantities of urine until it is well coloured. The chloroform is next thrown on a filter and washed with water; it passes through, and even with traces of bilirubin presents a yellow colour. Test portions of this chloroform extract as follows : — (1) By shaking with carbonate of soda we obtain an alkaline solution of the pigment, to which tlie ordinary nitric acid test may be applied, or the chloroform solution may be tested directly. (2) Dilute the chloroform solution or evaporate a little on a slide, and bilirubin will be obtained in microscopic crystals. The colour reaction can jilso be well seen inidur the microsco])e by treating the ciystallinu rosiihic with nitric acid. {?>) Carefully [)oiir a few drops of yellow nitric acid over a little of the chloroform oxti-act iu a test glass : the play of colours is •seen. (4) Treat with ozonisi-d sjiirifs of tiu-jK-ntine or with a trace of watei'y solution of iodine in puUtssic iodiile : a green colour appears. BILIARY UmXE. 535 (5) Shake a little some time with caustic potash, and a greenish solution of biliverdin is obtained. (6) The addition of strong sulphuric acid gives a green coloration. (7) Treat a little with l)romine water, and a series of coloured rings will be formed. {;/) By shaking the urine with ether the latter is coloured yellow. Pour this ether into a test tube and hold it over the mouth of a flask filled with strong bromine water : the ether will gradually assume a blue colour. Pathology. — The presence of the biliary acids in urine has been denied by several chemists, but HOPPE 8eyler has found them in more than 30 cases of jaundice, a fact which has so frequently been substantiated since that we may look on it as proved. But undoubtedly to obtain characteristic evidence of their presence in urine they must first be separated. These biliary acids are present and increased in some cases of jaundice and acute atrophy of the liver, and occasionally in pneumonia ; but their presence or absence is not of so great importance as some authors (Harley, &c.) have supposed, although their presence may at least indicate an accumulation of them in the blood, and consequently, if excessive, a tendency to paralysis of the nerves, particularly those of the heart (Eitter, &c.) The biliary pigments in excess will accompany the biliary acids after obstruction of the bile ducts, and especially when the jaundice coincides with acute inflammation or atrophy of the liver ; in certain disturbed states of nutrition also, as in starvation, diabetes, and after phosphorus poisoning and snake- bite, both bodies may present themselves in the urine, but with the pigments biliverdin and biliprasiu generally predominating (Vogel). If the liver is at all inactive in its functions, from disease or otherwise, it can easily be seen that an accumulation of pig- ment is likely to occur. This retention of pigment is often to be seen in degenerative changes of the liver and weakening of its blood stream ; as the result of the ingestion of ether, chloroform, or arseuiuretted hydrogen ; also in severe infective diseases, as in typhus, malaria, pyaemia, septic poisonings, and multiple abscess of the liver. The different forms of jaundice may be classified according 53o EXCRETA: THE F.ECES AND URINE. to their origin into ab'^jrptlon, asplrdt'ton, and suppression, icterus, together with what has been called blood icterus. 1. By a closure of the bile ducts the bile accumulates, followed by its reabsorption {cibsorjjtion icterus). This may occur in catarrhal jaundice, carcinoma of the liver, nutmeg and sj^philitic liver, cirrhosis of the liver, closure of the ducts by calculi, &c. 2. In other cases a sinking of the blood i)ressure in the liver leads to the same result {cvsjiiralion icterus), as in pylephlebitis and icterus neonatorum. The reabsorption may arise either from diminished pressure in the blood vessels, as in this form of jaundice, or from increased pressure in the bile ducts, as in jaundice from absorption. 3. The term suppression icterus is applied to the jaundice due to the cessation in the production of the biliary constituents in the liver and their accumulation in the blood through a deficient excretion. 4. In the form of jaundice to which Virchow has applied the term blood icterus there appears to be an increased decomposition of the corpuscles and a liberation of haemoglobin, which forms the source of a greatly increased production of bilirubin. From hfemoglobin is derived the hfematoidin of old extravasations, and this latter body is regarded as identical with bihrubin (.Jaffe, Heidenhain). A solution of hremoglobin injected into the blood causes jaundice and a separation of biliary pigment in the urine. Injection also of bodies that tend to dissolve the corpuscles, such as water, ether, chloroform, and biliary acids, effects the same thing. CHAPTER XXIV. MUCUS AND PUS; CIIYLURIA. Mucus in small quantity is a common constituent of the normal urine, forming a faint, flocculent, transparent cloud that deposits after a time. Vesical mucus is semitransparent and rich in corpuscles and epithelium, and, if the urine is alkaline, also in oxalate of lime and triple phosphate crystals. It is frequently found in urinary sediment and must not be confounded with albumin ; nor must the long cylinders or filaments of mucus that are often to be met with be mistaken for urinary casts. MUCUS is precipitaterl by the mineral acids, but it is soluble MUCUS AXD rUS; CIIYLUItlA. 637 in excess. It differs from pus in not being precipitated by neutral acetate of lead, wliich precii)itates tlie jtyin of pus. To detect ii in urliic treat a portion of that Huid with twice its volume of alcohol (95 per cent.), filter off the precipitate, and wash it in water. The urine is also rendered slightly cloudy by tlie addition of acetic acid, in whicli mucin is not soluble. A simple filtration of urine will not remove all the mucus, as mucin, it sliould be remembered, is soluble in a large quantity of water as well as in a slight excess of the mineral acids. To determine its amount dilute the urine (about 300 grams) with twice its volume of water and acidify strongly with acetic acid ; then cool to 5° or 6°, filter, and wash the precipitate with a little dilute acetic acid. It can thus be separated from albumin ; but if any pus or blood is present redissolve the precipitate in water slightly acidulated with hydrochloric acid, and saturate the solution exactly with caustic soda ; then re- precipitate the mucin by adding a few drops of acetic acid, and weigh it on a tared filter after it has been washed with alcohol and ether and dried. The thick glairy deposit occasionally formed by pus must not be mistaken for mucus. In the former case the urine is alkaline and crystals of triple phosphate are present. Mucus is specially abundant in catarrh or inflammation of the bladder or urethra ; numerous imperfectly formed mucus cells are then present with much epithelium. PUS may show itself in the urine in very small amount or as a bulky deposit resembling urates. The urine containing it is generally turbid when voided, and it soon deposits a dense yellowish white sediment. Some time after the urine has been passed the pus often assumes a slimy, ropy, viscid, and tenacious character, swelling out against the sides of the vessel, and capable of being drawn out into long tough strings. This ropiness is generally due to the action upon it of ammonia developed by the decomposition of urea. The same thing can also be effected by the addition of caustic potash. This reagent serves at the same time to distinguish it from pale urates, which are thus dissolved. When examined under the microscope the corpuscles 538 FXCliETA: THE F.ECES AND VBINE. appear as little granular globules, varying somewhat in appear- ance with the reaction of the urine ; they are cleared up by dilute acetic acid, a folded or cleft tripartite nucleolated nucleus coming into view at the same time. Blood corpuscles and triple phosphate crystals may also be present, and croupous shreds, especially after irritant diuretics. Source of the Pus. — Pus may appear in the urine in renal embolism, renal abscesses, suppuration of the pelvis of the kidney, discharge of pus from pelvic, perinephritic, and other abscesses, inflammation or cancer of the bladder, and suppura- tion of the prostate or urethra. In women the pus may have a vaginal origin and be due to leucorrhoea. The character of the admixed cells should be carefully ascer- tained, and the way in which the pus comes away should be noted — whether more abundant at the beginning of the act of micturition, as in urethral disease, or towards the end, as in cystic disease. When the pus comes from the kidney the urine is generally acid when passed, but when it is derived from the bladder the reaction is usually ammoniacal, especially if the suppuration is of old standing. In vesical pus too blood, if present, is mixed up with the mucus and pus, while in renal suppuration the blood lies usually on the top of the pus. Albumin can always be detected in the urine if much pus is l^resent, as by boiling, precipitation with mercuric chloride, acetic acid and potassic ferrocyanide, but generally only a haziness on the addition of nitric acid. It is therefore sometimes a matter of difficulty to decide as to its origin, for albumin m:iy be present also as a result of kidney disease. The diagnosis must here depend on the amount of the albumin relative to the quantity of pus, on the presence of casts, calculi, crystalline deposits, &c. CHYLTJRIA. — In this condition a milky and fat-holding urine is excreted. The quantity and sp. gravity of the urine remain about normal, the colour, however, being milky white to yellowish red, the reaction neutral or weakly acid, but easily becoming alkaline ; on standing a white layer may accumulate on the surface, or a coagulum may show itself. The white supernatant layer consists of very finely divided fatty particles, as can l)e shown with ether nnd acetic acid ; and in the sediment MUCUS AND PUS; CHYLURIA. 639 a few lymph cells or blood corpuscles may be met with. The presence of fine embryonic worms {filar'ui sanguinis) was dis- covered by Lewis not only in the urine, but also in the blood and the tissue of the kidney. Some have maintained the existence of abnormal communi- cations between the lymjihatic vessels and the urinary passages. The blood has also been seen to be very rich in fine free mole- cules (Scriba), which are said to find a passage through the membrane of the glomerulus. Very characteristic is the alteration often presented by the urine, the chylous aspect occasionally disappearing and re- appearing very rapidly. In addition to the ordinary urinary constituents, fat, lecitliin, cholesterin, and albumin have been obtained in chylous urine. The fat is generally under 1 per cent., though more may be jDresent. Different observers have also detected the presence of small qviantities of glycerophosphoric acid, peptone, sugar, phenol, and indican in different specimens. Fat and fatty matters, it may be said, are ex- tremely rare in the urine ; but, in addition to chylui-ia, an admixture of a large quantity of pus with the urine may lead to their presence ; fat is also occasionally present in fatty degeneration of tlie kidney and in acute phosphorus poisoning, but rarely in fatty degeneration of the epithelial cells of the urinary passages. To separate fatty bodies from urine a large quantity of this fluid is treated with ether, with which it is well shaken, then rendered alkaline with caustic soda, and again shaken up with more ether; this ethereal extract is distilled and the residue taken up in pure ether. The amount may be determined in this way by Aveighing the residue of the last ethereal extract. The presence of cholesterin in this I'esidue may easily be recog- nised by shaking it up with an alcoholic solution of caustic potash and then with ether, which latter dissolves the cholesterin and only a little of the soap formed. By evaporating the last extract we obtain the characteristic thin rhombic tables, to which the tests for cholesterin can be applied. 540 EXCRETA: THE F.ECES AND URINE. CHAPTER XXV. ADDITIONAL ABNORMAL CONSTITUENTS. Excretion by the Kidneys of many Oeganic and Inorganic Substances, and the Mode op Detecting some op Them. A sulphocyaoiide is said to be present in the mine of smokers. Sulphuretted hydrogen has been noticed in cases of tuber- culosis, variola, cancer, and enlargement of the bladder. Lactic acid has been met with in acute atrophy of the liver, and in leukaemia, rickets, osteomalacia, and trichinosis ; sarcolactic acid in acute phosphorus poisoning. Such fatty acids as formic, propionic, and butyric have likewise been observed. A great many bodies when taken are excreted by the kidneys almost unaltered, while others may be only slightly changed. I. Inorganic Substances. 1. The neutral alkali salts, as the chlorides, bromides, and iodides, appear unaltered in the urine. 2. The alkaline carbonates diminish the acidity of the urine, or render it alkaline. The carbonate of ammonia appears as urea, and does not influence the reaction. Salts of cossiuni, rubidium, lithium, &c., also a])pear quickly in the urine ; likewise potassic ferrocyanide. 3. The alkaline earths are discharged in the urine only in small proportion. 4. Salts of the heavy metals, as of lead, copper, mercury, antimony, and iron, and arsenious and arsenic acids pass into the urine only in small amount. The excretion of lead suits is favom'ed by the administration of potassic iodide. Prolonged use of salts of silver leads to a deposition of the metal in the glomeruli of the kidney, as well as in the rete Malpighii of the skin. 5. The acids appear as neutral salts. 6. Iodine appears as iodide, sulphur as a sulphate. AI)I)iriO.\AL ABNORMAL CONSTITUENTS. 541 II. Organic Substances. 1. Alcohol, uulcs.s ingested iu large amount, is generally completely oxidised, only traces appearing in the urine (Heubach, Binz). 2. After long administration of ddovoform the urine be- comes possessed of strong reducing properties, and urochloralic acid is found in it. The sodium salt of this latter body crystallises best, and has the formula CgH,„Cl3Na07 ; this acid appears to be a homologue of Jaffe's uronitrotoluic acid. Chloral also appears as urochloralic acid, the urine reducing sugar and polarising to the left. 3. The organic acids are generally oxidised, and their alkaline salts render the lu'ine alkaline ; but gallic, pyrogallic, picric, and hippuric acids are very slightly changed ; tannic appears as gallic acid, benzoic as hippuric. 4. The amido-acids go in part to form urea. 5. Uric acid appears as allantoin and urea, or as carbonic anhydride, oxalic acid, and urea. 6. The different vegetable pigments, and the odorous 2'jrhiciples of valerian, assaftetida, castor, saffron, and turpentine appear in the urine. 7. The alkaloids, as quinine, morphia, strychnia, &c., pass over in great part unoxidised into the urine. 8. Of aromatic bodies, such as the benzols and the like, some undergo simple oxidation, others reduction, and others again effect combinations with glycocin in the organism. Benzol appears as phenol and phenol sulphiuic acid ; carbolic acid as phenol sulphate, hydrochinon, and brenzcatechin. When phenol in any form is administered to a patienf internally the whole amount may appear in the urine, sometimes causing it to assume a greenish brown colour, especially in cases of poisoning; the colour, however, is not proportional to the phenol present. An absorption of phenol takes place when applied to the uncut skin as well as after operations, a precipitate of coagulated albumin sometimes separating in the latter cases on distilling the urine. In passing through the organism it is capable of combining with sulphuric acid, forming an ethereal sulphate, wliicli is afterwards eliminated by the urine as a o42 EXCliETA: THE F.ECES AND URINE. potassic or sodic salt. In the urine, especially of herbivora, it is constantly present, and it is possible that it has its source here in the decomposition of tyrosin. Glycocin, leucin, and sarcosin appear as urea; indol as indican ; Jcreatin as kreatinin ; and thein, theohromin, alloxan- tin, and allantoin as urea. Most of these changes are analytical as well as synthetical, water being eliminated, and the requisite oxygen supplied from the blood. Blood containing hippuric acid passed through a pig's or dog's kidney, when the renal artery is tied, gives rise to benzoic acid, the change being due to a soluble ferment or 'histozym' and not to the action of bacteria (SCHMIEDEBERG). Methods for Detecting some of these Heterogeneous Elements {after Salkowski, cix.) Potassic Iodide. — Add some drops of fuming nitric acid, then a few c.c. of chloroform, and shake well : the iodine is liberated and gives to the chloroform a violet tint. Potassic Bromide. — If miicli is present, on heating the urine as in the case of the iodide, the chloroform will attain a yellow colour. Lithia. — Evaporate the urine to dryness and incinerate the resi- due on a platinum cruciVjle ; treat this with water and a drop or two of hydrochloric acid, and evaporate the extract obtained ; this last residue is to be exhausted with strong alcohol, this diluted, and a clean platinum wire inserted in it and then placed in the colourless flame of a Bunsen lamp : a purple red colour will he given to the flame, and on spectroscopic examination a carmine red line will be seen at b and a second between c and d. Chloroform (GHCI3). — Draw a stream of air through the mode- rately warmed urine, and then through a red-hot porcelain tube filled with fragments of porcel;iin, and finally through a set of Liebig's potsish bulbs containing silver nitrate solution acidified with nitric acid. The chloroform is decomposed, and the hydrochloric acid gas generated is precipitated by the silver solution. When the freshly-passed urine is boiled with an alcoholic potash solution and anilin a penetrating and characteristic smell is evolved : CHC]3-h3KH04-CV,H,NH2=3H20-f-3KCl-|-CV,II,NC. Chloroform may also be detected by proceeding as in the next panigi'Mph Iodoform (CIIl-j). — Distil tho mine with steam until 50 c.e. have pas.sed over ; then mix the distillate \\itli a little potash ley and ADDITIONAL AByORMAL CONSTITUENTS. 543 shake it with ether in a tap funnel ; the ethei-Gil solution is evapo- rated to dryness, the residue treated with absolute alcohol, and the alcoholic solution tested by pouring it into a short test tube in the bottom of which is a very little alkali phenate ; cautiously heat the mixture over a small flame, and in a few seconds a red deposit appears that dissolves with a crimson colour in a few (hops of dilute alcohol. Phenol (C,;H,iO). — Acidulate the urine with sulphuric acid and distil; test the distillate with ferric chloride, which gives a blue colour, or with bromine water, which gives a white crystalline pre- cipitate of triln'omophenol. Salicylic Acid (CyHgO^).— Shake about 30 c.c. of urine, that has been acidified with sulphuric acid, with an equal volume of ether; then decant the ether and treat it with a little ferric chloride, when a violet colour appeals. If much salicylic acid is pi'esent the blue . colour may be obtained by testing the urine directly. The presence of free mineral acids in any quantity hinders or pi-events the reaction ; organic acids also hinder, but to a less extent. Pagliani therefore recommends the addition of the ferric chloride to the filtrate from the precipitate caused by lead acetate, and the gradual addition of sul- phuric acid until the red colour due to acetic acid just disappears, when the violet coloration due to salicylic acid will be seen. Chrysophanic Acid (CigHigO,) appears in the urine after its ap- plication to the skin, and also after the use of rhubarb and senna. The urine is generally of a strong brownish yellow colour, and be- comes a permanent purple red on the addition of caustic soda. Santonin (CigHjgOa). — After its use a decomposition product is present in urine, owing to which this fluid generally acquires a yellow colour, which is transitorily reddened by the addition of caustic soda or ammonia. To distinguish between the urine coloured by it and by chrysophanic acid the following reactions will suffice : — C 1 1 ry f ophanic acid S an t on i n 1. Alkalies give a permanent red A cheriy or purple red colour, which colour. disappears after 24 hours. The tint is more of an orange after rhubarb or senna. 2. AUuiline carhonatcs give a rapid The red colour appears slowlj' and red coloration. gradual] v. 3. Reducing agents in the urine ren- The colour remains. dered alltaline remove the colour. 4. Precipitate with baryta water and The colour of the tiltrate is not re- tilter : the tiltrate is decolourised. moved. ftuinine (CaoHoiNaO,).- — Part appeals in the urine unaltered, part as oxychinin (Kerner). The urine turns the polarised ray from o4i IJXCIiErA: THE F.ECES jyi) URIXE. 0-3 to O'-t to the left. Add a few drops ammonia to the mine, shake well with some ether, remove the ether with a pipette, and evaporate the ethereal extract. The residue is to be dissolved in a little slightly acidified water and again precipitated with ammonia. Dissolve nj) this last residue with water and treat it first Avith chlorine water and then with ammonia : a green colour is obtained ; or if ferrocyanide of potassium is also added, a red colour. To detect very small quantities precipitate the lu-ine with tannic acid and wash the precipitate by decantation ; then treat it with caustic lime and evaporate to di-yness ; digest the residue with hot chloroform, and evaporate the chloroform extract. The quinine can be dissolved up from this last residue by means of acidulated water (Persoxxe). Morphine (OiyHigNOg). — Only a part of the morphine taken into the stomach is aljsorbed, some being lost in the fa-ces ; even when in- jected subcutaneously it is partly destroyed by the alkaline blood, so that only very minute traces, or at the most the products of its de- composition, can be detected in the urine (Landsberg). Borntkager could not discover any morphine in the urine of a pei'son who daily took it in large doses ; but it always appeared there when it was sub- cutaneously injected. In a patient into whom a considerable amount was daily injected, one-fourth was found unaltered in the urine, and some was likewise discovered in the fteces (Marme). Evaporate the urine to a syrup, and extract it several times with aVj.solute alcohol ; evaporate this alcoholic extract to dryness, and dissolve the I'esidue in a few drops acetic acid and water, shaking up the watery solution with warm amyl alcohol (70°) until it is colour- less • then concentrate it over a water bath, and having rendered it strongly alkaline with ammonia shake it two or three times with hot amyl alcohol, which takes uj) the morphine and yields it on evaporation. 1. Dissolve a little in .strong ,viil|.]jiiiic acid, add a drop of water and a small fragment of red jKHassic chioniate : a mahogany colora- tion is produced. 2. Heat the solution in siilphnric acid in au air bath at aliout 150° for 10 minutes or so, let it cool, and then add nitiic acid, when a V>eautiful dark violet or blood red colour is produced. The other alkaloids are examined for in the same way. Test their action on frogs, and note if the pupils are dilated (atropin) or the muscles tetanised {ulrych aiv), itc. Lead, Silver, and Mercury. — In poisoning by /eruZ the metal may V)e detectetl iu the urine and all the organs of the body. In rabbits to which lead had been given in do.'-esof 3 to 4 milligrams daily traces ADDiriONAL ABNORMAL CONSTITUENTS. 64o were found in tlio urine after tlie first tliiy. The lead is best detected by treating the residue of the evaporated urine, or of any organic fluid, by first destroying all organic matters with hydrochloric acid and potassic chlorate, and testing the dissolved residue with sulphu- retted hydrogen in an alkaline solution ; or the lead can be separated by electrolysis, the solution, freed from organic matter and acidulated with hydrochloric acid, being placed in a bell jar closed below with parchment ]ia])er and floated in very dilute sulphuric acid. The positive electrode of a small battei-y lies on the parchment diaphragm and the negative electrode on the other side. The electrodes are platinum foil, and in 24 hours the lead deposited on the positive electrode is dissolved in boiling nitric acid, the solution evaporated to dryness, redissolved in water with the addition of caustic soda, and tested with hydric sulj:)hide. To detect silver evaporate the urine and destroy the organic matter in the residue by fusing it with potassic nitrate and sodic hydrate ; extract with water, and dissolve what remains in nitric acid ; this last solution is to be filtered, evaporated, dissolved in water, and precipitated with hydrochloric acid. In the case of mercury the residue of the urine is freed from oi-ganic matters by means of potassic chlorate and hydrochloric acid, the filtrate subjected to electrolysis, the mercui-y being deposited on a gold electrode. The deposited mercury is then converted into iodide, the electi-ode being introduced into a glass tube, which is then drawn out into a capillary tube at one end and sealed at the other. On heating the bulb the mercury sublimes and passes into the capil- lary portion of the tube. Cut off part of the bulbous portion of the tube and seal it up again after having enclosed a fragment of iodine ; the iodine vapour penetrates the capillary tube and converts the mercurial suljlimate into iodide. Or the urine may be diluted with water or a 2 per cent, sodic chloride solution, mixed with slaked lime, and some potash solution introduced, the whole being enclosed in a large flask. To the latter a U tube filled with glass wool moistened with silver nitrate is attached, and the whole then heated in a calcium chloride bath to 130° to 140°. The glass w^ool is next to be con- verted into iodide, as described above. N X .-)4G EXCRETA: THE F.ECE.S AXlJ UlilNE. CHAPTER XXVI. TABLE FOR THE EXAMIXATIOX OF MORBID URIXE. 1. Qiiantity. — Collect in a clear vessel the total urine passed in the 24 hours (normally 1,500 to 1,700 c.c. = 52 to 59 oz.) 2. Density. — Ascertain this with a urinometer (the normal is 1018 to 1025 ; to get it with any degree of accuracy, and so as to be really of service clinically, a sample taken from the whole mixed urine passed in the 24 hours should be tested). To obtain approximately the solids in the 1,000 parts from the density multiply the last two numbers of the latter by 2 or 2-33 (Trapp). [Normally 40 to 60 grams (617 to 925 grains) of solids in 1,000, or 4 to 6 per cent., of which urea = 370 grains, and inorganic salts, about the half of w*hich are chlorides, = 300 to 350 grains.] 3. Note the Colour, whether pale, yellow, brown, red, or black ; the clecirness or turbidity ; the presence or absence of a sediment; and the reaction (of the fresh urine), whether acid, neutral, or alkaline. (If the litmus paper has been reddened and turns blue again on drying, the acid is free carbonic ; while if the litmus has been coloured blue but reddens again when the paper dries, or is gently heated on a slip of glass, the alkalinity is due to ammonium carbonate ; but if it remains blue, then the alkalinity is due to fixed alkali.) 4. Test for Albumin by boiling the clear acid urine ; if it is not already acid add a few drops of acetic acid, and then note if any precipitate appears on boiling. (When albumin is present the sp. gravity is generally low and the urine pale in colour.) (a) If it is ivhite and disapijears on the addition of nitric acid it consists of earthy phosphates. (The nitric acid should not be added too sparingly.) {b) If it is ivhite and does not disappear on the addition of nitric acid it is albumin. But instead of appearing white it may lie fp'ee a- coloured, from the presence of Inliary pigment ; or reddish broivn, from tlic presence of blood. I^ay the test tube aside for 24 hours and then note the TABLE FOR THE EXAMINATION OF MORBID URINE. Gt7 amount of the deposit. Roughly, if the precipitate is insignifi- cant, the loss of albumin in the 24 hours is under 2 grams ; if moderaie, from G to 8 grams ; if considerable, from 10 to 12 grams ; wliile if very large, about 20 grams. If a more accu- rate determination is required see pp. 507-510. To confirm the presence of albumin, paiticukirly if it is in small amount, or if there is any doubt as to its existence in the urine, pour some pure nitric acid into a test jar, and allow the urine to flow slowly down the side of this vessel, held inclined at a considerable angle, and to spread itself out upon the nitric acid ; then note the appearance of a white cloud at the line of juncture of the tiuo fiuids. Or a saturated solution oi picric acid may be used in the same way. Another confirmatory test is to boil the urine with a few drops of Millon^s reagent, when an intense; red coloration will be produced ; or add to the urine a little jjliosphotungstic acid, which precipitates even very dilute solutions of albumin if a little time is given. In slight cases of albuminuria the albumin may be absent from the urine passed before breakfast and present in con- siderable proportion after a large meal, such as dinner or break- fast. It is advisable, therefore, in cases of doubt or difficulty, to test samples of the urine of the early morning, of that passed after dinner, and of the urine voided at night. 5. Test for Sugar. — The urine is pale, abundant, and of high sp. gravity (1030 to 1050) if sugar is present. The urine should be free from albumin : if not, acidify it strongly with acetic acid, boil for some time, and separate the precipitate by filtration ; or if much pigment is present filter the urine through animal charcoal. (ft) Add a little gf the alkaline solution of bismuth (see p. 65) to the fresh urine and boil for a few minutes : a broivn or 6^ac/»; coloration or precipitate is indicative of sugar ; a white precipitate is due merely to bismuthic oxide. (b) Confirm the presence of sugar. (1) Add to it one-fourth its volume of caustic soda solution and then, drop by drop, a solution of cupric sulphate (1 : 10) until a blue solution is obtained ; now heat, and a yellowish red precipitate is thrown down. Better results will be obtained by diluting a little U N 2 518 EXVliETA: THE F.ECES AM) UJiiyE. Feliling's solution with water, boiling tlie mixture, then adding the urine gradually, heating after each addition. If sugar is present in not too small amount an orange or red precipitate makes its appearance. Also, for the sake of avoiding any possibility of reduction of the copper by other reducing bodies than sugar, it is advisable, if any uncertainty exists, to mix a little Fehling's solution with the urine and lay it aside for 12 to 2i hours : sugar alone, of any of the probable urinary con- stituents, effects the reduction in the cold. G. Test for Bile. a. Bile Pigment. — The presence of albu- min does not interfere with the pigment reactions. If, indeed, in the previous testing for albumin a greenish precipitate was obtained, then the presence of bile pigment is indicated, (a) Pour a little yellow nitric acid into a test tube, then in- clining the test tube let the urine trickle slowly down its side, so as to form a layer over the acid ; at the point of contact a green hand first appeal's, which spreads upwards, and is suc- ceeded inferiorly by a blue, a reddish violet, and a yellow layer. (6) Spread a drop of the urine upon a white plate and bring a drop of yellow nitric acid into the middle of this drop : a play of colours is produced, beginning with green and ending with red and yellow. (c) A delicate plan is to filter the urine, dry the filter, and then allow a drop of yellow nitric acid to fall down the inside of the filter: the play of colours is well marked. The presence of indican or the pigments df rhubarb, senna, santonin, &c., may lead to some difKculty. With the indican, however, the appearance of the first green band, so charac- teristic of bilirubin, is wanting, while the play of colours is absent with the other pigments. {d) With only traces of pigment the above methods may fail ; the following then is to be tried : Acidify the urine with acetic acid and shake well with a little cliloroform ; if pigment is present the chloroform assumes a yellow tint. Kemove the chloroform with a pipette, allow a drop of it to evaporate on a microscope slide, and look for bilirubin crystals. Shake the rest of the chloroform extract with carbonate of soda, and an alkaline solution of the pigment is obtained, which is to be treated with nitric acid a.s in (a) or (b). tault: for Tin: exam ixat ion of Monnin urine. 549 u. Biliary Acids. — («) Add a few dro})s of cane sugar sjrup to the urine, and then a little gum mucilage or a scraping of hard soap ; shake for some time until a good froth is ob- tained ; now incline the test tube and allow a drop or two of strong sulphuric acid to flow down into the froth ; if the biliary acids are present a beautiful purple will show itself in the froth along the line of the sulphuric acid, either at once or after the side of the tube has been gently warmed. (?>) Dip a piece of filter paper into the urine in (a) after the addition of the cane sugar, and lay it aside to dry ; then bring a drop of strong sulphuric acid in contact with it by means of a glass rod, and in a short time a violet red spot will appear. (c) It is best, in case of doubt, to isolate the biliary acids as follows : Precipitate the urine with acetate of lead and a few drops of ammonia ; collect the precipitate on a filter and wash it with water; next boil it with alcohol and filter hot; add some drops of sodic carbonate solution to the filtrate and evaporate to dryness. Extract the dry residue with boiling absolute alcohol, which is to be placed in a flask, and after having been evaporated to a small volume ether added to it, the flask corked, well shaken, and laid aside : a resinous pre- cipitate soon appears, which is to be separated and a watery solution of it tested as in (a) or {h). 7. Test for Earthy Fliosphates. — Add to 15 to 20 c.c. urine in a test tube 5 to 15 drops of a solution (1 : 12) of carbonate of soda : the urine becomes opalescent or gives a precipitate. This indication is readily confirmed by adding a drop of nitric acid to another specimen of urine, and dipping into it a piece of ammonium molybdate paper, when the latter assumes a yellow colour, which is more marked if the acidified urine has been previously boiled. The precipitate that an alkaline or faintly acid urine may give on boiling, and which disappears on the addition of nitric acid, is due to earthy phosphates. Approximately the amount may be determined by noting the character and amount of the precipitate with the sodic car- bonate (Benecke). If no cloudiness even is produced the phos- phates are below 0-02 per cent. 550 EXCRETA: THE F.ECES ANT) URINE. A slight opalcsccMicc ..... A stronger „ . • . . . A mai-ked ,, ..... A „ turbidity ..... A moderate jjrecipitate gvadually ajjpearing A strong ,, appearing immediately A precipitate occupying nearly the whole lluid {Aoniial amoitiit ...... Per cent. = 0-04 tc . 0-06 = 0-07 „ 0-00 = 0-10 „ 0-12 = 0-14 „ 0-15 = 0-lG „ 0-18 = 0-li) „ 21 = 0-20 „ 0-2(; = O-Ofi „ , 008) 8. Test for Uric Acid. — Filter 200 c.c. urine, add 10 c.c. hydrochloric acid, and lay aside for 24 hours : a reddish or brownish yellow crystalline precipitate on the sides of the tube. Collect these by decanting the urine and filtering. Place a few of the crystals thus obtained on a microscope slide, and dissolve them in a drop or two of caustic potash with the aid of heat ; stretch a piece of linen thread through the drop and apply a cover glass ; now let fall a few drops of hydro- chloric or acetic acid at the side of the cover glass over the uncovered part of the linen thread ; examine under the micro- scope in a few minutes, and note the appearance of transparent rhombic tables in the neighbourhood of the thread. The murexid test can also be applied, if required, to .some of the crystals placed in a small porcelain capsule. Add a drop or two of nitric acid, warm, and evaporate at a gentle heat ; moisten the reddish residue with ammonia, and it will become purple red, or with caustic potash, and a purple blue colour will be produced. If excess of urates is present the urine will not be clear, but it will become so on boiling, and will respond to the above tests. 9. Ttst for Blood if the urine is of a red, brown, or brown- ish black colour, and particularly if there is a reddish-coloured deposit. (a) Boil a little of the urine with some strong caustic potash, and let it stand for a short time : earthy phosphates will be precipitated, coloured brown to a blood red and exhibiting marked dichroism with reflected light. Urine containing ciiryso})hanic acid or the pigments of rhubiirb or senna gives a similar reaction ; but there is no dichroi.'^iri, and instead of Ihc coldui- of the precii)itate being TABLE FOR THE EXAMINATION OF MORBID URINE. 551 brightened by the action of mineral acids, as is the case with blood, it is somewhat darkened. In cases of doubt aj*}*!}' the following tests in addition : — (6) Boil the urine with acetic acid, collect the brownish red coaguluin on a filter, wash it, and then warm it with a little alcohol acidified with su]})huric acid: a red or- brownish red alcoholic solution is obtained, which is to be filtered and examined with a spectroscope ; if sufficiently concentrated it will give the absorption bands of hiematin, a dark band between C and D, and another lighter but broader band extending from midway between D and E to F, though sometimes this latter may appeiir as two bands instead of one. (c) Add a little freshly prepared tincture of guaiacum to an ecjual volume of spirits of turpentine in a test tube, shake so as to form an emulsion, and pour the urine down the inside of the inclined test tube, so as to form a layer: if blood is present the resinous precipitate takes a blue colour. (d) A little of the deposit should be transferred to a slide and examined under the microscope. Look for the non- nucleated flattened discs, which may be more or less swollen and decolourised ; then, if corpuscles are to be seen, and there is doubt as to their identity, irrigate with strong solution of magenta, which stains sporules and nuclei of epithelial cells ; or with a solution of eosin, which imparts a rosy orange tint to the coloured corpuscles. (Where blood is present it is often of importance to get the patient to micturate into two clean vessels, so that the urine first passed may be examined separately from that passed later.) 10. Test for Indican. — Mix 40 drops or so of urine with about 4 c.c. fuming hydrochloric acid ; then agitate with some chloroform, which on settling to the bottom will be of a blue coloiu' if indican is present. Or wann the urine with twice its volume of nitric acid, and then shake with a little chloroform : a blue chloroform layer is obtained, that gives an absorption band between c and d. 11. Test for Excess of Urea. — The urine is of a deep colour and a high sp. gravity (1030 to 1040). Add to some lu'ine in a large watch glass an equal voluuie of pure nitric acid, and 552 EXCRETA: THE F.ECES AND URINE. float the glass on cold water. If the urea is in much excess crystals of nitrate of urea will make their appearance inside half an hour, or much earlier, according to the amount of urea present. 12. Crystalline Constituents. — Evaporate some urine to a thick syrup, place drops of this upon several glass slides, and apply thin cover glasses ; after crystallisation has gone on for some time examine under the microscope. Add a drop of acetic acid to one of the droj^s of the syrup and insert a fila- ment of flax or silk therein : let this slide stand under cover for twelve to twenty-four hours, when it is to be examined. CHAPTER XXVII. URINARY SEDIMENTS OR DEPOSITS. Certain extraneous matters may be found in examining urinary deposits, and the student should in the first place make himself familiar with their appearance, so as not to mistake them for true urinary deposits. The most common of these extraneous deposits are fibres of cotton or flax, hairs of different animals, portions of feather, wool, oil globules, granules of starch, pieces of vegetable tissue, splinters of w^ood, chalk, sand, &c. It is ahvays desirable to examine the deposits early, as some of them are liable to undergo perceptible changes in a comparatively short time. A light cloudy deposit after the urine has stood a few hours is normal ; it generally consists of epithelium or a little mucus from some jjart of the urinary tract. When the urine is turbid and acid on emission, the turbidity is due to the presence of pus, blood, or mucus; but if alkaline, to the presence of phosphates. The deposits rnay be classified into organic and inorganic. The organic consist of epithelial cells, casts of the uriniferous tubules, pus, blood, oil globules, &e. ; while the inorganic are UlilNARY SEDIMENTS OR DEPOSITS. 553 such bodies as uric acid, urates, oxalates, phospliates, and carbonates, chiefly of the alkalies and alkaline earths, leucin, cystin, and tyrosin, &c. Pus varies in appearance according to the reaction of the urine. When it is acid the pus tends to sink to the bottom of the vessel as an opaque, creamy, greenish yellow layer, diffusing readily on being agitated and subsiding again slowly and gelatinising when mixed with an equal volume of caustic potash. When the urine is alkaline the pus is viscid and ropy, very tenacious and stringy, not diffusing readily on agitation, and generally mixed with earthy phosphates. Mucus also tends to sink to the bottom of the vessel, and is very tenacious and ropy ; earthy phosphates are frequently deposited. The deposit should be alloivedto settle, and the supernatant urine decanted, or the sediment removed by means of a pipette ; and as a general rule portions of the deposit, if a copious one, should he examined at different levels. By using a conical glass sufficient deposit may be obtained for examination even from a small amount of urine. The character of the deposit should then be noted— whether it is (1) light, fioccitlent, and transparent, consisting of mucus, epithelium, or other bodies, such as sarcinte, spermatozoa, casts, &c., in small quantity : (2) dense and opaque and of con- siderable bulk, as urate of soda, forming a lateritious nut- brown sediment ; phosphates, urine usually alkaline ; pus, forming a creamy deposit rendered glairy by potash : (3) crystalline or granular, occupying a small bulk at the sides or bottom of the vessel containing the urine, and coloured or transparent, as uric acid, generally of a mahogany brown colour ; blood and other corpuscles and cells ; oxalate of lime (seldom forming a deposit visible to the naked eye), cystin, &c. (Beale). We generally find that the deposit varies with the reaction of the urine ; thus from an acid urine we may have a deposit of urates, uric acid, tyrosin, or cystin ; from an alkaline urine, urate of ammonia, phosphate of lime or magnesia, triple phos- phate, or carbonate of lime ; and from a nearly neutral urine, oxalate of lime. 654 EXCRETA: THE FAECES AND URINE. Removal of Deposit. — Plunge a pointed pipette, whose upper orifice is closed with the forefinger, into the deposit at the bottom of the vessel holding the urine, and then raise the forefinger slightly, upon which some of the deposit will enter ; now press the forefinger tightly down and remove the pipette. If the deposit is present in but small amount, or if only a small quantity of urine can be obtained, the precaution should be adopted of attaching a piece of indiarubber tubing provided with a clip to the upper end of the pipette. Then on removing the pipette from the urine lay it aside suspended for some time. As a preliminary examination it is expedient to proceed as follows (after Eobin) : — 1. Warm a little of the deposit in a test tube with some of the urine itself : urate of soda or am^monia readily dissolves. 2. Add to a little of the deposit half its volume of caustic potash : urates are dissolved and a clear solution obtained ; pus becomes transparent, glairy, and viscid ; phospjhates remain un- changed. If the deposit is rendered viscid without being cleared up, then pus and phosphates are probably both present. 3. If the deposit does not disappear when heated, add a few drops of acetic acid : earthy phosphates are dissolved. 4. If insoluble in acetic acid add to a fresh portion a few drops oi dilute hydrocldoric acid: a clear solution which gives a white precipitate when neutralised with ainriionia probably indicates oxalate of lime. 5. If still insoluble, to a fresh portion add a few drops of liquor ammonice : if it dissolves, and the solution on evapora- tion leaves hexagonal crystals — cysiin. 6. Also, if insoluble in the hydrochloric acid, test for uric acid by adding a drop or two of nitric acid to a little of the deposit on a small porcelain dish, heating to dryness over a spirit lamp, and adding a drop or two of ammonia : a purple coloration indicates uric acid. 7. Test the solubility of the deposit in ether: if soluble, and the ethereal solution yields an oily residue, fatty viatter is present. A partial clearing up occurs with chylous urine. 8. Examine the deposit under the microscopje, and note URINABY SEDIMENTS OR DEPOSITS. 555 whether it is crystalline or amorphous, or consists of rounded or organised particles. (rt) GrystalUne in Whole or in Part. — Uric acid in lozenge- shaped crystals, but the form varies immensely. This is the most frequent form of deposit. Khombs and rectangular prisms are the most com- mon forms, and they are usually of a reddish yellow colour. In case of doubt it is always advisable to dissolve a little of the deposit in a drop of potash on a slide, and then add excess of acetic acid ; cover and examine in a couple of hours, when if uric acid is present small colour- p,^, 35._ oxalate of lime less rhombic crystals will be obtained. ^i-L"" voids. ^''''''' '"''''"'' Triple -phosphate occurs in stellate, feathery, or obliquely truncated triangular prisms, soluble in acetic acid ; phosphate of Ihne in granules and occasionally in radiating crystals ; oxalate of lime in octohedra or dumb- bells; cystin in rosette-like tables; cholesterin in rhombic plates. (h) Rounded or Amorphous Particles. — Oil globules as spherical, very refractile bodies with dark borders ; chylous 'matter as very minute fatty granules in an opaque and milky urine : fatty matter is generally in globules, chylous matter in a molecular condition. Alilk can be detected by its character- istic globules, and by the urine clearing up after the addition of a few drops of acetic acid and ether, chylous urine clearing up on addition of ether alone. Urate of soda or anvmonia occurs in amorphous form or in small rounded masses, and is readily soluble when heated ; phosphate of soda is soluble in dilute acids : on adding acetic acid the phosphates and car- bonates disappear, also the urates, but uric acid crystals will appear in the place of the latter. (c) Organised Particles. — Corpuscles of mucus, pus, or blood, epithelial scales, casts, sarcinse, &c. Irrigate with dilute acetic acid and stain with magenta. Pus, as we have seen, is- rendered glairy by potash, and it is generally associated with crystals of triple phosphate. A little albumin also can be de- tected in the urine when pus is present, derived from different 556 EXCPxETA: THE F.ECES AXD URIXE. parts of the genito-urinary iimcous membrniie, even from the kidney itself ; but to determine its exact seat of formation is difficult; some idea, however, may be gained by noting the character of the epithelial cells mixed with it, and the presence or absence of different crystals; thus pus from the bladder generally contains crystals of triple phosphate, but these are often absent if the pus comes from the pelvis of the kidney or the kidney itself. When blood is present the urine has gene- rally a smoky tint, and if the urine is acid the deposit is brownish, but if alkaline the colour is brighter and redder. The corpuscles will vary in their appearance according to the reaction and density of the urine ; in dilute and alkaline urines they very soon loose their characters. The opportunity may be taken here, Lefore tabulating the differ- ent deposits, to examine one of these deposits in a little more detail. Cystin very occasionally occurs as a greyish crystalline deposit. Urine containing it is generally faintly acid, yellowish-green coloured, and turbid when voided ; the addition of acetic acid increases this turbidity by causing more cystin to be deposited. It occurs mostly in the urine of children or j'oung adults, at times as much as 0-.393 gram being excreted in the 24 hours, and is supposed to result from some dei'angement of the liver, the sulphates being generally increased at the same time unless much cystin is discliarged, in wdiich case the absolute amount of sul- phuric acid is lessened. In some cases this cystinuria runs in fami- lies, and seems to be hereditary. In very small amount, it may be said, it has been regarded as a normal urinary constituent (LoBiscn and Ebstein). Cystin forms transparent six-sided, or occasionally rhomliohedral, plates. It is soluble in mineral acids, oxalic acid, and caustic alkalies, "from which it is readily precipitated as a white powder, from the acid s>lutions by ammonium carbonate, and from the alkaline solu- tions by acetic acid ; l)ut it is insoluble in water, alcohol, and ether. Heated on platinum foil it hums with a grcriiish-ljluc lh\mo, giving Fio. 3G.— Crystals of Cysti*?. URINARY SEDIMENTS OR DEPOSITS. 657 off a charjji/fir acid [C„II„N03]. 1. Granules round or oval in shape, contour decided and dark, either isolated or united in groups of three or four, arranged in lines, &c. ; or granules very jjale, small, transparent, and difficult to dis- tinguish, united in irregular flakes. (This body may also appear as wedge-shaped crystals with ob- liquely cut bases, and may be arranged in rosettes ; the crystals may likewise form needles, or prisms collected into radiating clusters, &;c.) 2. Granules rounded, isolated, with concentric or radiated stria!, and more or less opaque and dark. (Only rarely found, and then gene- rally accompanying the earthy phosphates in an alkaline urine ; it may occasionally form imperfect dumb-bells.) 3. Little reddish or 3'ellowish granules, sometimes very snuiU and disposed in a ramified serie.-^ rplious R'idh's. Action of acetic acid Soluble without Phu-iphtite af Jhiie evolution of [t^^iaCf'^^JJ- gas. Soluble with evo- lution of bub- bles of gas. Soluble, with the ap pea ranee after a time of Carhonafr of lime [CaCO,]. Urates [C,H.,(NII,).,N\03] [CiHjNajN.Og]. 600 EXCRETA: THE F.ECES AMJ URINE. (recent sediments); sometimes more voluminous in the form of globules with black contour and yellow centre, united eii masse, or else isolated and covered with points (old sediments). (Urate of ammonia is found only in alkaline urine, the other urates generally in acid urine.) 4. Very fine isolated granula- tions with molecular movement. 5. Rounded gi-anulations of variable size and strong refracting power, soluble in a mixture of al- cohol and ether, especially after the addition of a little caustic soda. Action of acetic acid colourless rhombs of uric acid. Insoluble. Insoluble. Molecular [irauula' tio/is. Fatty particles. B. Organised Deposits. \. Of a Cellular, more or less Ruanded Form. Action of acetic aci(i Swollen and decolour- ised by dilut e acetic acid ; not stained by carmine. 1. Globules circular with smooth and crenated margins, without nuclei, centre depressed, isolated, and often surrounded by threads of fibrin or mucus ; the urine contains albumin. 2. Round or oval globules wiih faintly marked outlines, of a faint grey colour, finely granular and nucleated ; isolated or grouped, and often surrounded by strings of mucus. At first the pus corpuscles are sepa- rate, but they soon run together, so as to form a considerable grey or yellowish white sediment ; and if the urine is alkaline the corpuscles appear much swollen up and transparent, often only their nuclei being visible. 3. Very small round or oval re- fracting globules, presenting brilliant nuclei or warty expansions on tbeir sur ace ; isolated or in strings. 4. Little vegetaVjle organisms in tlie form of cubes {sarciiif/<), or as cellular threads forming fungus growths (orthallus), often with fruc- tifying spores (sugar fungus, y;t'//i- cilliuin /jlaucHiii). Become pale, nuclei being brought into view, which are stained by carmine. Not affected ; not stained by carmin, but the nuclei are coloured yellow by iodine. Colenred cor- puscles of the hluod. L e a cuci/tes (mucus and pus corpus- cles). Spores. Fungi. I URINAHY SEDIMENTS OR DEPOSITS. 5G1 Action of acetic acid 5. Very small oval, li^aline, and Not cbaracteristicall}' highly refractilc corpuscles, each modllicd by re- furnished with a l(ing and slender tail. fi. Cells with thick walls, fre- quently tailed or spindle-shaped, often forming small brownish de- posits in which blood corpuscles are numerous, and shreds of tissue, luumatoidin crystals and rosettes of calcic oxalate crystals occasionallv agents. Elements rendered more distinct, par- ticularly the nuclei. Sjjermatozoa. Cells and co?'- puiclcs of cancer and tubercle. ^P ^s '9^ I I'lG. 37.— ErnBtUAL Cells in Uiunary Dei-osits. Ejiithelhim of difftrcnl kinds fcvnd in winai~y dtposits: «, from ureter ; 6, from urethra ; c, frcm pelvis of kidney ; ithelial). (c) Yellow, glistening, outlines regular and well defined ; insoluble in water, lime water, or dilute acetic acid; soluble in strong acids and alkalies ; and do not shrink in alcohol or tannic acid (hj/aline). 2. Very short and minute trans- parent rods or cylinders, in great numbers, and often presenting a molecular or undulatory movement. Action of acetic acid Rendered transparent. Uiinary casts. Not modified by acetic acid, which, however, .slackens or arrests their movements. Vibnoncs URINARY SEDIMENTS OR UEI'OSITS. 5G3 III. Flalies 01- Filaments. Action of acetic acid Filaments very fine and {a) Not modified by acetic acid. Fungi. often intersecting. (J>) Rendered transparent by acetic Clots of Jibria. acid, the fibrillary aspect dis- appearing and giving place to a swollen, transparent, amor- phous mass, which again assumes its fibrillar appearance after the action of caustic potash. * (f) Rendered more distinct by Mucus. acetic acid, which gives it a striated or punctated aspect. Action op Caustic Potash (10 per Cext.) ox Deposits Examined UNDER the Microscope. 1. Deposit disappears : Urates — the older the period of formation the slower the solution. Uric acid — slow and progressive disappearance. Blood corpuscles— ^swell and dissolve. Leucocytes — become transparent and dissolve rapidly. Fjnthelial nuclei — clear up. Urinary ca.sts „ Fibrin and mucus — the granules present are dis- sociated. 2. Deposit modified : Epitheliums— tha xxudai gradually disappear, the cell swelling up into a transparent vesicle with indis- tinct outline. Pavement epithelium resists the action longest. 3. Deposit not modified : Triple pho.-^phate. Phosphate, carbonate, and oxalate of lime. Spores, vibriones, bacteria — movements arrested. Spermatozoa. Vegetable filaments. In the table j)recediiig the last it will be seen that after the action of acetic add the deposit disappears, as with the phosphates ; is modified by being rendered transparent, «&:e. {epitheliay &c.) i is not afl'ected, as with nric acid, oxalate of lime, &c. ; or new appearances present themselves, as crystals of uric acid, &c. Hippuric acid may present itself in the form of long, rhomboidal, four-faced prisms, which may be confounded with the triple phosphate, but is distinguished by its insolubility in 5U4 EXCRETA: THE FJiCEH AND URINE. dilute acids and its solubilit}^ in warm alcohol. It is a very rare deposit, but it may present itself after the administration of benzoic or succinic acids and after the ingestion of large quantities of fruit, &.c. CHAPTER XXVII r. PHYSIOLOGICAL AJVI) PATHOLOGICAL CONDITIONS IN WHICH DIFFERENT SEDIMENTS OCCUR. 1. Mucus and Ejpitheliwdi in blenorrhoea, catarrh of the urinary organs, &c. 2. Pus in suppuration in the urinary tract, as kidneys, ureters, bladder, urethra, &c. ; also, in females, from uterine and vaginal discharges. If the cells are round and smooth and show double or treble nuclei readily on the action of acetic acid, the discharge is of a more or less laudable kind, and more likely to be produced by a simple catarrh, than if the action of acetic acid brinsfs into view irregular or ill-defined nuclei. 3. Phosphates. — Especially in chronic diseases and in alka- line urine. The presence of the triple phosphate is not signi- ficant unless present in freshly voided urine ; it then points to the occurrence of decompositions in the contents of the bladder and to the possible formation of stone. Crystalline phosphate of lime is said frequently to accompany the waste of tissue occurring in phthisis, diabetes, paralysis, &c. Amorphous phos- phates, if persistent, indicate a low state of health, and may precede the formation of urinary calculi. 4. Uric Acid and Urates. — In acute fevers or exacerba- tions of chronic febrile conditions these are frequent. In a state of health a deposit often occurs after excessive bodily exertion, profuse sweating, excess of food, late hours, &c. A sediment of uric acid alone is very infrequent, but it has been met with in leukjcmia. If the uric acid is deposited early in fresh urine it points to a uric acid diathesis, gravel, or the formation of a calculus. The occasional appearance of urates or of ujic acid is of no importance; it is only tlieir constant or frequent occurrence that indicates some error in one or more DIFFF.IiEXT .SEDIMENTS. 505 of the body functions. The de^wsit is frequently present in derangements of the digestive and hepatic functions. Very red urates are commonly associated with disease of the liver. 5. Oxalate of Lime. — Sciiultzkn states that there is a daily excretion of 0*1 gnim of the oxalate, but it is increased after certain foods, drugs, or iiTegularities of diet ; thus after sugar in excess, tomatoes, rhubarb, sorrel, gentian, valerian, &c. ; also after excesses of carbonated drinks, such as champagne, seltzer, or soda water, &c., or of alkaline bicarbonates or alkaline salts of the vegetable acids ; likewise in disturbed respii-ation, hindering absorption of oxygen, and thus leading to incomplete oxidation of certain of the non-nitrogenous constituents of the food, as in chronic pleurisy, tubercle of the lung, emphysema, and in dyspepsia, &c. It may show itself also in subacute rheumatism, diseases of the spinal cord, pityriasis, or sperma- torrhoea ; and Meckel is of opinion that a deposition of the oxalate occurs in the mucus of the urinary tract under certain specific catarrhal conditions. A deposit of this body is frequently found associated with a series of nervous and dyspeptic symptoms indicating what is termed an oxalic acid diathesis, and consti- tuting oxaluria ; a modified form of this may also accompany many diseased conditions, as anaemia, cancer, and jaundice. Excess of acid in the system, moreover, is said to cause an increase in the discharge of the oxalate, together with an excess of phosphate of lime — a condition frequently associated with flatulent dyspepsia. In most of these diseases in which the oxalate is abundant there is probably more or less of an increased tissue metabohsm, the urine at the same time containing an excess of urea, urates, and phosphoric acid. The crystals of this body are soluble in a solution of acid sodic phosphate ; after the urine has been passed this phos- phate gradually diminishes, and accordingly the oxalate is deposited. 6. Hippuric Acid. — After the use of fruit, particularly cranberries, after the ingestion of benzoic acid, and in cases of diabetes and chorea. 7. Tyrosin indicates a great decomposition of protein sub- stances, but at the same time the occurrence of some break in 5G0 EXCRETA: THE F.ECES AND URINE. the continued downward metamorphosis, as in acute atrophy of the liver. 8. Xanthin and Hypoxanthin have been observed in leu- kaemia and after the use of sulphur baths. 9. Cholesterin has been found accompanying purulent dis- charges and in old inflammations of the kidney and its pelvis. 10. Sarcinoi are frequent in spinal cord affections, together with pus, phosphates, and ammonic carbonate (Heller). 11. Alfjce and Fungi appear particularly in diabetic urine. CHAPTER XXIX. URTNAIiY CASTS. In most cases of renal disease, such as congestion, inflammation, and the like, in which albumin makes its appearance in the urine, we also find casts of the uriniferous tubules, but the casts appear later than the albumin (Overbeck). With the appearance of albumin in the urine a diseased condition of the epithelial lining of the urinary tubules sets in (Senator) ; but Perls has obtained casts by compressing the renal veins, without any diseased condition of the epithelium showing itself; the occurrence, nevertheless, of a primary disease of the glomeruli in these cases is very probable (Nussbaum). Some of the fibrin-formers in the blood transude into the tubes, and there undergoing coagulation form casts of these tubes, and according to the condition and character of the tube at the time the appearance of the cast will vary. When the cast is dis- lodged and forced onwards it may carry with it the epithelium that lined the tube, or it may be a mould of the lumen of the tube alone ; of course when the cells are discharged with the cast their character may often afford evidence of the condition of the kidney : thus, should the epithelium be degenerating, the altered cells will give evidence of this ; so also the presence of blood corpuscles would indicate haemorrhage, and that of pus cells the existence of sup})uration. It is difficult, however, to imderstand how a cast of a con- URINARY CASTS. 507 voluted tiil)e could find its way into the urine if it has first to pass tlirough the narrow-looped tube of IIenle, unless this had previously undergone dilatation, which is just possible ; and, on the other hand, it does not appear probable that all the casts found in the urine come from the collecting: tubes alone, although ViRCiiow was long of opinion that almost constantly. Fig. 38.— Eenal Ca^t.-;. Uena! Casts. — 1. Epithelial casts : the middle one of tlie tliree is highly magnified ; In that to the right the cells are scattered. 2. Granular casts : iu the higliest one there are blood corpuscles. 3. Hyaline casts of large and small diameter. 4. Fatty casts. Rendl Cells.— a in a normal and 6 in a state of fatty degeneration ; c, free fatty granu'es. Bodies that may be mi5tal<;en for casts : (1) mucus and (2) spermatic casts ; (3) liuman liair ; (4) wooUen hair ; {[>) flax and (6) cotton fibres. if not invariably, the casts were formed in these tubes. It is possible also that small casts may grow larger by successive deposition of new layers on their exterior. Classification of Casts. — Casts are of various kinds, of which the following are examples : — I. 1. Epithelial, which indicate a dcfquaniation of the urinary tubules. 563 EXCRETA: THE F.ECES AND URINE. 2. Hyaline, mostly long and narrow, and often so trans- parent and homogeneous as to escape observation miless the deposit has been treated with some iodine or magenta solution. Most of these hyaline casts swell up in pure water, and dissolve in it between 30° to 40^ or at 60°. They are also soluble in 10 per cent, solutions of carbonate of soda or ammonia, in the mineral acids and the caustic alkalies ; they shrink up in alcohol, and in solutions of tannic acid and the salts of the heavy metals ; and when heated with Millon's reagent are coloured violet. These may be the so-called fibrin cylinders or the amyloid casts, the latter of which glisten like wax and are perfectly homogeneous, but giving the blue reaction with iodine and sulphuric acid. 3. Brownish yellow nucleated or gramdar casts are generally wider in diameter than the hyaline casts, and often present fatty particles or degenerated epithelial cells in their interior. They do not swell up in water or in solutions of sodium choride or carbonate, nor shrink in alcohol or tannic acid ; but they dissolve in hydrochloric ( 1 per cent.) and glacial acetic acid, and in alkaline solutions. 4. FoMy Casts. — The fatty particles may be studded over a transparent cast or collected in dark granular masses. 5. Blood Casts may appear, sometimes consisting almost entirely of blood corpuscles closely adherent and not much altered in appearance, or presenting a few scattered corpuscles along a fibrinous cast, or of corpuscles that have been as it were crushed together. 6. Pus Casts have also been described. Reddish brown cylinders, made up of collections of urates or accumulations of bacteria, may make their appearance in urine. II. Cornil admits four varieties of casts — mucous, alhu- niinous or hyaline, epithelial, and fibrinous. (1) The mucous are pale, with ill-defined outline, and occasionally with a finely granular aspect ; they are not stained by carmine. (2) The albuminous or hyaline possess well-marked outlines, and are often very long and twisted ; they are soluble in caustic potash, insoluble in acetic acid, and coloured by iodine and carmine. (3) The epithelial present swollen epithelial cells, that are UJtlNAllY VASTS. £60 generally very granular in appearance and indlt rated \vi(li fatty particles. (4) The fibrinous are finely striated or granular, often containing blood corpuscles and swelling np and be- coming more hyaline in acetic acid. III. Leube gives the following : — 1. Blood casts, consisting of coagulated blood. 2. Hyaline casts, mostly very small and colourless, and may be homogeneous, slightly striated, or molecular in appear- ance ; they may contain leucocytes or epithelial cells, and are strongly coloured by gentianin. These are generally regarded a.s fibrinous, but more correctly they should be looked on as albuminoid in their nature, as they do not give the reactions of fibrin (Rovida). That they arise as the result of a coagulation of some kind, under the influence of dying leucocytes, there seems every reason to believe ; and it may be possible that the fibrin has been metamorphosed in some way. 3. Epithelial. — («) Simple unaltered — the cells distinct. (6) Metamorphosed epithelium — generally yellowish in colour ; the epithelial characters not always very evident ; sometimes the appearance may be almost homogeneous. They are generally broader than the hyaline casts, and may present in their interior more or less altered epithelial cells, fatty particles, micrococci, wandering cells, crystals, or precipi- tates of uric acid, &c. The cells of the epithelial casts either break up into a finely granular mass, which later assumes a hyaline appearance, or they may swell up, run together, and become homogeneous at once. Examination of Casts. — The specimen of urine should be laid aside in a small conical vessel and allowed to settle. With a pipette a little of the sediment is removed and examined under the microscope. On account of the transparency of some of the casts the examination should be made, in case of doubt or diffi- culty, with a comparatively faint illumination through a small diaphragm, and sometimes it is advisable to stain the deposit with a little magenta; and where there is very little sediment it is often advantageous to allow the deposit to form in a pipette whose upper orifice is closed. 570 EXCRETA: THE F.ECES AND UltlNE. Pathology. — In many affections, such as fevers, severe inflamma- tions, and the like, Gists may appear iu the urine, and probably result from some affection of the kidneys (congestion or the like) dependent upon the primary disease ; but simple hjrperajmia of the kidneys, it should be remembered, does not necessarily produce casts. Casts are generally present in albuminuria of renal origin ; but in some forms of renal affection they are very scanty, and accordingly difficult of detection. Casts are found in (1) acute nephritis, either idiopathic or as a seqiiela of scarlatina, cholera, typhus, or variola ; and in (2) chronic Bright's disease. Althoiigh, therefore, casts point to renal affection, we must not at once conclude the existence of Bright's disease. The irritation, for example, of a renal calculus may induce their formation ; and in the urine of jaundice they may be found without any renal disease : indeed, it is possible for an occasional cast to be found in perfectly healthy urine. Signijicance of Casts. — We must not expect to find in one case epithelial casts alone, in another only granular casts, in ar.ofcher fatty casts, and in another large waxy casts, and so on ; but several varieties may be met with in the same case, and the diagnosis must be founded upon the relative i)roportion of the different casts and of other deposits, as no one form can be regarded as pathognomonic of any particular disease of the kidneys. Thus the presence of uric acid crystals, blood corpuscles, and renal cells points to the case being acute, while the occurrence of a number of oil casts renders it probable that the case is chronic (Beale). Epithelial and blood casts as a general rule are typical of a disease of recent origin ; transparent, large, waxy casts, mixed with dai-k granular casts, point to a chi'onic disease ; and epithelium and casts containing much fat indicate fatty degeneration (Roberts). Hyaline cylinders are found in all cases of albuminuria, whether of nervous or organic origin, and in urine of fevers, and they are especially frequent in glomerular nephritis and contracted kidney, although in this last epithelial casts are also present. The few casts that are met with in amyloid kidney are mostly hyaline ; but as this latter condition is frequently associated with chronic inflammation other forms of casts may be present, as also leucocytes and blood corpuscles. In chronic nephritis especially the number of casts is particularly great, and there may be nucleated epithelial casts, or hyaline casts very broad and long, pale or dark yellow ; and together with the casts blood corpuscles, fatty detritus, and degenerated fatty cells are present. In acute croup)ous nephritis the number of tlie casts is also considerable, and they may be of the hyaline or epithelial variety; they are associated with a copious deposit of blood corpuscles and epithelial cells from the kidney. 671 CHAPTER XXX. CALCULI. In the following chapter, for the sake of convenience, bib'ary as well as urinary calculi, &c., will be considered. The substances that go to form these bodies are comparatively few in number. They are uric acid and urates, 2)hosphate of lime and magnesia, oxalate and carbonate of lime, carbonate of magnesia, cholesterin, xanthin, cystin, biliary pigments, and coagula. Occasionally calculi may consist entirely of one constituent, but it is more frequent to find two or more arranged in layers ; but although most usually consisting of several constituents, one generally predominates, and the calculus is named accord- ingly. The combinations most commonly met with are uric acid and urates ; uric acid, urates, and earthy phosphates ; oxalate of lime and earthy phosphates ; uric acid, urates, and oxalate of lime ; uric acid, urates, oxalate of lime, phosphate iind car- bonate of lime, and triple phosphate. These calculi are usually formed of layers, generally concentrically arranged around a nucleus of some kind, which may be a small calculus of renal origin, a clot of blood, some mucus, epithelium, or a foreign body ; and in the case of uric acid calculi oxalate of lime very frequently forms the nucleus, while for other calculi the most frequent nucleus is uric acid itself. In 80*9 per cent, urinary calculi the nucleus consists of uric acid or urates, in 8*6 j)er cent, of earthy phosphates, in 5-6 per cent, of calcium oxalate, in 3-3 per cent, of foreign bodies, and in 1*4 per cent, of cystin (Ultzmann). The following is the frequency 'per cent, of the different uiinary calculi (Fourcroy and Vauquelin) : — Uric acid Oxalate of lime Urate of ammonia and earthy phosphates Oxalate of lime and uric acid in laj'ers . Oxalate of lime and earthy phosphates . Eartliy phosphates All other calculi, as cvstin, xnnthin, &c. Per cent. 25-0 200 11-7 50 2-5 2-5 57-2 EXCllETA: THE F.ECES AND URINE. To see the concentric layers of a calculus divide it equa- torially with a fine saw, then grind the cut surface on a hone with water, and having washed and dried it, apply a coat of varnish. In the case of small brittle calculi it is better to grind half the calculus away. No definite crystalline structure is usually to be seen unless occasionally on the surface. DiflEerent Forms of Calculi, witli their General Characters. — 1. The most frequent urinary calculi are those consisting of iiric acid. To other calculi they may be said roughly to stand in the proportion of two to three, or according to some authorities they form only one-fourth of all calculi. They are hard, generally of a flattened ovoid shape, and of all sizes from a pin's head up to a goose's egg ; in colour they are reddish or yellowish brown, smooth or slightly tuberculated on the surface, and crystalline or earthy in structure, consisting of a series of con- centric layers. The calculus evolves an odour of burnt horn when heated on platinum foil, and is soluble in a dilute warm solution of caustic potash, from which it is precipitated by carbonic or acetic acid. 2. Urates. — These calculi usually contain soda, ammoniaj and lime, and commonly oxalate of lime is also present. (a) Urate of ammonia calculi are rare, being occasionally met with in young children. They are small, rounded, smooth or slightly tuberculated, and of a pale slate or clay colour, but in the fresh state of a dull, opaque white. (6) Simple urates of soda and lime are not found forming calculi of themsel ves,but they are often present with other bodies. 3. Oxalate of lime calculi are frequently met with, according to some authorities forming one-fifth of all calculi. They have most commonly a nucleus of uric acid or urate of lime, and are often of considerable size, brownish in colour or of a dark olive or dirty purple tint (mulberry calculi), and possessing a very irregular and rugged surface, by which they can be recognised. They may also be met with in the form of small oval or rounded bodies, smooth and even polished on the exterior — the so-called hemp-seed calculi. The white crystalline variety is compara- tively unfroquent. An oxalate stone with a plios])]iatic crust is a frequent form. Most mixed calculi contain more or less of the calcic oxalate. CALCULI. 673 The powdered calculus is insoluble in acetic acid, but readily soluble in dilute mineral acids, and precipitable therefrom by ammonia in excess. These calculi may begin to be formed in the kidney, and when they arrive in the bladder fresh oxalate may be depo- sited, or uric acid or phosphates, according to the condition of the urine. 4. Calculi of the j)hosphates are common. Less than 10 per cent, of all calculi have a nucleus of mixed phosphates, but they enter into the composition of at least 34. per cent. They are generally light in colour and earthy in appearance. While the phosphates are very often deposited on other calculi it is rare to find uric acid, urates, or oxalate of lime deposited on the phosphates. The mere presence of deposits of the earthy phosphates in the bladder, without the presence of some binding material like mucus or blood, is insufficient to give rise to a calculus (Thudicuu.m). (a) Phosphate of lime calculi are usually smooth on the surface, and their lamelke are, as a rule, very regularly arranged, separating readily in thin crusts. They are almost infusible before the blowpipe. These calculi are easily soluble in nitric acid, and are precipitated in a gelatinous form from this solution by excess of ammonia. If the precipitate is dis- solved in acetic acid the solution will give a yellowish white precipitate of phosphate of iron on the addition of a drop of ferric chloride, and a white precipitate of oxalate of lime on the addition of oxalate of ammonia. These calculi are sometimes found in the kidney. (6) The triple, or aramioniaco-tnagnesianphospJiate is some- what rare as the sole constituent of a calculus, but it consti- tutes a large bulk of the mixed forms. It is of a drab or stone colour and its surface is rough. It is easily soluble in hydro- chloric acid and precipitated therefrom by neutralisation with ammonia ; boiling with caustic potash decomposes it, causing ammonia to be evolved and magnesia to be precipitated. This calculus swells up, gives off ammonia, becomes grey, and ulti- mately fuses in the blowpipe flame. (c) The fusible calcidas is a mixture of the triple phos- 574 EXCRETA: THE F.ECES AND URINE. phate and of the phosphate of lime, with a considerable ad- mixture of mucus and organic matter. Next to uric acid it is the most common component of calculi. This calculus is generally oval or irregular in shape and resembles chalk in appearance and consistency, the hardness being nearly inversely proportional to the amount of triple phosphate present. It is easily fusible before the blowpipe without being consumed, a property that characterises it and has given to it its name, evolving ammonia and watery vapour in the process, and leaving behind a mixture of calcic phosphate and magnesic pyrophosphate. The powdered calculus is readily soluble in mineral acids, and is reprecipitated in stellate crystals by neutralising with ammonia. 5. Xanthin and cystin calculi are extremely rare, parti- cularly those of xanthin. The xanthic calculus (CgH^N^Og) is of a light or dark yellowish brown colour, with occasional scat- tered white spots glistening like wax on friction. It is almost insoluble in water, alcohol, and ether, but soluble in alkalies and in warm hydrochloric acid ; its solution in nitric acid leaves a bright reddish yellow residue on evaporation, which becomes a violet red (not a purple colour, as in the case of uric acid) when treated with caustic potash. Xanthin solutions give a voluminous yellow precipitate with phosphomolybdic acid. Xanthin belongs to the uric acid group of bodies and is closely related to sarkin. It has also been found in very small amount in the spleen and liver and in muscle. The cystin calculus is more or less transparent and waxy in appearance and crystalline in structure. Cystin calculi scarcely form 1 per cent. ; they are generally small and may consist of pure cystin, when they are of a yellowish white or a pale greenish grey colour, or of cystin combined with earthy phos- phates, when they are dirty greenish blue or grey, or of a fawn Ijrown. Cystin dissolves readily in ammonia, and the solution on evaporation leaves pure cystin in six-sided plates. 6. Fibrinous calculi, probably only the residues of altered blood clots, resemble yellow wax, and are soluble in acetic afid and caustic potash, l)ut iiisohibk; in water, alcoliol, and ether. 7. Concretions of blood and of fatijj or sapo7iaceous sub- CALCULI. 675 stance (^iivosteaUlh) are occasionally met wilJi, as also calculi of silica and carbuitate of lirae. The carbonate of lime cal- culi are often found in the herbivora, and they may show themselves in great numbers in the kidneys of these animals. They are mostly white, but at times of a brown or violet colour. 8. Calculi of cholesterin, generally mixed with more or less bilirubin and calcic phosphate, which are frequent in the gall bladder, have also been met with in the urinary bladder, in which case there is generally a layer of uric acid. But there is some doubt as to this form of calculus, and in one of the cases in which it was found a communication existed between the gall bladder and the urinary bladder through a patent urachus. 9. Prostatic Calculi. — These are found in the follicles of the gland ; they vary much in size, and are more or less rounded, with flattened sides, consisting of phosphate of lime with traces of carbonate of lime and organic matter. 10. Calculi may also be met with in the nasal fossae, in the bronchial tubes, in the salivary glands, and in the intestines. These consist generally of mucus, epithelium, albumin, and earthy phosphates and carbonates, and sometimes also a little fat. Indigo has been found in a reual calculus (Ord). Preliminary Examination of a Urinary Calculus. — Make a section through the centre and scrape some of the substance off oiie of the cut surfaces ; sometimes it will be advisable to make independent analyses of the different layers, in which case, of course, portions of these layers will be collected. A. Some of the j^ovxlered calculus is calcined on platinum foil. The foil is heated to redness in the flame of a spirit lamp, and if a carbonised mass lemains the red heat is to be continued until it disappears or forms a white ash, (1) If it is carbonised, then bui'ns, and leaves no sensible residue, it most pro- bably consists of loric acid, urate of ammoniaj, or such rare bodies as cystin, xanthin, or fibrin. (2) If it carbonises at first, then burns, and leaves a sensible residue, it contains both organic and mineral constituents. Uric acid is the most frequent organic constituent; accoi'dingly it should be looked for, and some of the jwn-'dered calculus should be boiled vnth excess of ivater and filtered while hot. Let the filtrate cool, and a deposit indicates urates of soda, lime, or potash ; or evaporate the filtrate to the sixth of its volume, and mic acid and any urates present will be thrown down. Ammonia, lime, and 576 EXCRETA: THE FAECES AND URINE. magnesia may also be present, and these can be detected as follows : Boil a little of the filtrate with a few drops of caustic potash, and test the vapour given oft" with a rod moistened with hydrochloric acid ; the presence of ammonia will be indicated by white fumes as well as by the smell. Then add to the rest of the filtrate some chloride of ammonium and carbonate of soda : a white precipitate indicates lime ; filter, and add to the filtrate a little ammonia and sodic phosphate : a precipitate indicates magnesia. The 7'esidus insohthle in the boiling ivater may contain phosphates or oxalates. Treat it with acetic acid and filter. The filtrate will contain the earthy 'phosphates. Wash the residue and dissolve it in hydrochloric acid : if it dis- solves without effervescence, and the solution supersaturated with ammonia gives a crystalline precipitate, oxalate of lims is present, (3) If the calculus leaves a residue and undergoes little or no blackening under the heat, it is composed of inorganic substances, of which the most frequent are oxalate of lime and the phosphates. B. Digest some of the powd.ered calculus with caustic ammonia^ filter, and evaporate the filtrate, when, if cystin is present, micro- scopic hexagonal tables will be obtained, which dissolve in caustic potash, and when boiled with an alkaline solution of plumbic oxide give a deposit of lead sulphide. C. Dissolve a little of the calculus in nitric acid and evaporate the solution to dryness : {a) a yellow residue rendered orange by caustic potash in the cold, but violet when heated, indicates xanthin ; while (Jj) a p>inh I'esidue which gives a 2^urple colour with ammonia marks ^lric acid. Examination of a Biliary Calculus. — Biliary calculi (see Bile) may contain any of the following : cholesterin, pigments, biliary acids, mucus and epithelium, earthy salts, particularly carbonate of lime, and fats, like palmitin. Cholesterin is the most abundant ingredient, and often it occurs alone or combined with a variable amount of biliary pigment. Analysis. — Powder the calculus, digest with hot alcohol, and filter : the filtrate contains fat and cholesterin ; the latter will separate in crysbils on the alcohol cooling, and the fat will be obtained by evaporating the alcoholic solution after the separation of the choles- terin. 8ome of the resinous products of the decomposition of bile may also be found with the fat. The residue left after the action of the alcohol is to be treated with dilute hydrochloric acid, which dissolves up the inorganic salts, and any effervescence will indicate the presence of carbonic acid. The undissolved residue consists of biliary pigments, which are to be tested with nitric acid. CAI^CULI. 577 The following method may be adopted : Digest a little of the powdered calculus with hot benzole and filter; thLs removes the cholesterin. Wash the i-esidue with alcohol, then dry it and treat it with ether and a few drops of nitric acid ; the f itty acids are thus removed. What is left on the filter is now washed with water, when the phosphates and nitrate of lime and magnesia ai-e extracted. The final residue contains the biliary pigments mixed with a little earthy salts (Thudichum). So far, then, as the action of heat is concerned we find that calculi may be arranged in three classes. 1. Combustible — uric acid, urate of ammonia, cystin, xan- thin, cholesterin, biliary pigments, and coagula. 2. Partially combustible — urates of soda, potash and lime, and oxalate of lime. 3. Incombustible — inorganic constituents alone. By means of the following table (Salkovvski) a calculus can be readily identified. Powder the calculus finely and burn a little on platinum foil, noting whether it consumes away completely or only partially. I. Com,pletely Combustible. — Digest a little of the powder with dilute hydrochloric acid and warm gently. a. The powder dissolves completely or nearly so : cystin, xanthin. (1) Treat a little of the powdered calculus with ammonia and filter : on evaporating the 61trate cystin crystals are left behind. Cystin stones are generally small, smooth, and yellow. (2) Dissolve a little of the powdered calculus in a porcelain dish with nitric acid and evaporate : a bright yellow xanthin residue, that becomes violet red when treated with caustic potash. Xanthin stones are very rare. h. The powder dissolves imperfectly or not at all. Filter, and wash the insoluble residue. (1) The residue : uric acid. Confirm by the murexid test. The stones are variable in size, moderately hard, and reddish yellow or bi'ownish in colour. (2) The filtrate may contain ammonium chloride, xanthin, or cystin. Try for ammonia by warming a little cf the solution with sodic carbonate or hydrate, and testing the va[)our by the smell, with red litmus, and with hydrochloric acid fumes. r P 578 EXCltETA: THE F.ECES AND URINE. Stones of lu-ate of ammonia are mostly very friable and of a dirty greyish or yellowish white colour. A mixture of xanthiu and cystiii is lare. II. The calculus blacke.ns, hut is not combustible. A slight blackening indicates the presence of an organic urinary con- stituent. Dio'est some of the finely powdered calculus with dilute hydro- chloiic acid over a flame : a rapid escape of bubbles indicates carbonic anhydride. a. Solution complete : absence of uric acid. b. Solution incomplete. Filter : the residue may be uric acid or an albuminous body. The presence of uric acid is easily determined by the murexid reaction. Render theJiUrate weakly alkaline with ammonia, and let the test tube containing it stand in some cold water for a short time ; then boil it and acidify with acetic acid : either a clear solution is obtained or a white jndverulent jjrecijntate. (Yellowish white flocks occasion- ally present are due to ferric phosphate. By filtering them off, dissolvina; in hydrochloric acid, and testing the solution with potassic ferrocyanide a blue precipitate is obtained.) c. The white jjulverulent precipitate, insoluble in acetic acid, consists of oxalate of lime. Collect it on a filter, wash, dry, and io-nite it on platinum foil : cai-bonate of lime is obtained, mixed with a little caustic lime; it has an alkaline reaction, and efiervesces on the addition of hydrochloric acid. d. The filtrate may contain phosphoric acid, lime, magnesia, potash, or soda. (1 ) Test a portion with uranic solution or a drop of ferric chloride : a yellowish white precipitate indicates j^hosplioric acid. (2) Treat the rest of the filtrate with oxalate of ammonia : a white precipitate indicates lime. Warm the fluid slightly and filter. (j) To a part of the filtrate add a little sodic phosphate and ammonia : a crystalline precipitate, that forms gradually, is triple phosphate and indicates magnesia. (ij) Examine another part of the filtrate for ammonia by boiling it with carbonate of soda and testing the vapour with litmus, &c. (iij) Test a third part for soda and potash (although this is scarcely necessary) as follows : Evaporate to dryness, ignite, and then dissolve up the residue in water to which a few drops hydrochloric acid are added ; now stir well in a white porcelain dish with a little platinic chloride, and a yellow crystalline i^rccipitato indicates jwtash. CALCriJ. 579 If the precipitate is transferred to a slide and examined under the microscope it will be seen that tlie crystals of the potash salt are octohedral and do not i)olarise, while the crystals of the sodic salt are acicnlar and do polarise. The flame also is to be examined spectro- scopically, when a clean platinum wire moistened with the fluid is inserted in it ; note also if the flame is blight yellow, or if it shows a violet tint when looked at through a piece of cobalt glass. In phosphatic stones we generally find both lime and magnesia, although the crystalline phosphate of lime may occur alone; phos- phatic stones are also more or less white and earthy-looking. CHAPTER XXXI. SYLLABUS OF PRACTICAL COURSE. I. Hydrocarbons. Starch. — 1. Prepare a solution (p. 2). 2. N"ote the precipitation of this solution by tannic acid (p. 47), 3. Add a few drops of solution of iodine (p. 2) to a little of the stai'ch solution, and a hhie coloration will be produced; also irrigate the scraping of a sliced raw potato upon a glass slide with some of the same solution, and note, under a high power of the microscope, the dark blue staining of the starch granules. 4. Add to some gelatiuous starchy mucilage a little lukewarm watery infusion of malt, and warm gently for a few minutes, when a thin fluid will be obtained containing sugar. Lay this aside, and test it aftei-wards for sugar (p. 46). 5. Starch is a colloid. Show this by means of a small dialyser (p. 47). Dextrin. — 1. Prepare by boiling a little starch paste with dilute sulphuric acid (p. 48). 2. Test with iodine solution, and note the red coloration ob- tained. 3. Note its precipitation from aqueous solutions by the addition respectively of alcohol, lime water, and a mixture of ammonia and basic acetate of lead, but not by the latter salt alone. Glycogen. — 1. Prepare by Brucke's method (p. .50). The pre- sence of glycogen in the liver has thus been demonstrated. 2. Show the i:iresence of sugar in the liver, Avhich has been derived from a conversion of the glycogen (p. 54). p r 2 680 EXCRETA: THE FJilCES AND URINE. 3. Prepare the liver ferment (p. 5G). 4. Test the glycogen with iodine solution, and note the reddish coloration (p. 56). 5. Test also with caustic potash and cupric sulphate, and note that the blue coloration does not disappear on boiling (p. 56). 6. Convert glycogen into sugar according to the methods given in paragi-aphs 3, 4, and 5, p. 56, and lay aside to be subsequently tested for sugar. 7. Precipitate a watery solution with acetate of lead. Grape Sugar. — 1. Prepare from cane sugar and honey (p. 61). 9. Boil a solution with half its volume of liquor potasste, and note the brown tint acquired by the liquid. 3. Apply the copper tests on p. 63. 4. Test with cupric sulphate and caustic potash (p. 64). 5. Boil a little of the solution with some alkaline solution of oxide of bismuth (p. 65, iij), and note the brown or black coloration due to the metallic reduction. 6. Apply the fermentation test according to method a or d, p. 66, and examine the growing yeast under the mici^oscope (p. 68). 7. Determine quantitatively the sugar in a solution, or in diabetic urine — [a) with a saccharimeter (p. 74); (h) by Feeling's method (p. 75) ; (c) and by the differential density method (p. 80). Pats. — 1. Shake up a little oil in a test tube with some white of eo'o' and note the formation of an emulsion ; then examine a drop of this under the microscope, when the oil will be seen to be broken up into small globules, varying in size and shape, w hich are maintained, apart by their albuminous coatings. 2. Shake up a little oil with some caustic potash, and the oil will be saponified. 3. Apply the delicate test (p. 87, i) for the presence of a fatty body. II. Nitrogenous Bodies. Albumins. — 1. Prepare an albumin solution (p. 97). 2. Carefully perform test i, p. 98. 3. Test with nitric acid as in 2, p. 98, using a very dilute albumin solution. 4. Test with picric acid in the same way. 5. Add some acetic acid to the albumin in solution and then a little potaasic ferrocyauide. SYLLABUS OF I'liACIICAL COURSE. 5S1 6. Add some acetic acid and tlien an excess of a saturated solu- tion of sodic chloride or sulphate. In all the ahove precipitates will be obtained. 7. Separation of Albumin from itx Solutions. — Mix equal parts of the albumin solution and of a solution of grape sugar ; acidify the mixture with acetic acid and add an equal volume of a saturated solution of sodic sulphate; then boil for some time and filter. The sugar will be found in the filtrate. Albuminates. — 1. Prepare an alkali albuminate (jx 101, a, \), and note that its sokition is not coagulated by boiling. 2. Neutralise a solution of alkali albumin with acetic acid, and observe the precipitate that appears. 3. Boil a little solid alkali albumin with water; divide the solu- tion into five portions, and proceed as follows : — (rt) Pass a current of carbonic acid gas through one of the specimens, and a precipitate will form. (b) Saturate another with powdered magnesic sulphate, and a precijjitate will likewise appear. (c) Add alcohol to a third, and no precipitate will show itself. {(I) Neutralise a fourth specimen with dilute acetic acid, and a precipitate will be thrown down. {e) Add a little sodic phosphate and a few drops of litmus solution to another specimen ; then netctralise with dilvite acetic acid, and it will be seen that no precipitate occurs until a considerable excess of the acid has been added. 4. Prepare an acid albuminate as in J, 1, p. 101 ; also by gently warming a dilute solution of albumin with a little dilute hydrochloric acid. The same result may often be readily obtained by rinsing ont a test tube Avith nitric acid, and then pouring into it a little very dilute albumin solution ; the whole is then to be very gently wai-med for a few minutes. {a) Boil a little of the albuminate thus obtained, and it will be seen that if the conversion has been complete no pre- cipitate will appear. {!>) Neutralise a little of the solution with dilute caustic potash, and a precipitate will show itself, which will occur even after the addition of sodic phosphate. Prejxiration of Certain Other Albumiyis. — 1. Separate serum albumin from a little blood serum or hydrocele fluid by the addition of acetic acid drop by droj) till a flocculent precipitate is obtained (p. 103). 582 EXCRETA: THE FAiCES AXD UEIXE. 2. Prepare vifeUin by digesting some yolk of egg with, water and ether so long as any yellow coloration is extracted. The residue is vitellin. Dissolve it in sodic chloride (10 percent.), and precipitate it therefrom by adding an excess of water acidulated with a few drops of acetic acid (p. 106). 3. Separation of paraglohulin ivom. the lens. Rub up a crystal- line lens in a mortar with a little washed sand, then with some water, and filter : paraglohulin is present in the filtrate, and is thrown down by the passage of a current of carbonic acid gas, or by the cautious addition of dilute acetic acid (pp. 106, 296). 4. Prepare mi/osin by washing some finely divided muscle in water, and rubbing the washed mass in a mortar with ammonic chloride solution (12 per cent.) ; strain through muslin after 4 hours, and then filter, allowing the filtrate to fall drop by drop into a tall cylinder nearly full of distilled water. The myosin separates in small flocks (p. 108). 5. Prepare fihrinoplastin by diluting blood serum with ten times its volume of distilled water and passing a stream of carbonic acid gas through the diluted fluid for half an hour (p. 110). Show also its precipitation by the addition of a little dilute acetic acid, or of an excess of powdered sodic chloride. 6. 'Pve\)?iYQ jihrinogen by diluting hydrocele fluid with ten volumes of water and then passing a current of carbonic acid gas through the diluted fluid for an hour or so (p. 110). 7. Dissolve separately the fibrinogen and fihrinoplastin thus pre- pared (the latter contains blood ferment mixed with it) in some dilute solution of sodic sulphate, and mix the solution together : fibrin will thus be generated. 8. Prepare _^6H?i by washing some blood clot (p. 114). 9. Prepare casein by diluting milk with ten times its volume of water, then acidifying with acetic acid, and subsequently passing a current of carbonic acid gas (p. 117). 10. Prepare syntonin by digesting for a few hours finely minced muscle in dilute hydrochloric acid (^ per cent.) and neutralising the diluted filtrate therefrom with sodic carbonate (p. 118). 11. Test some purified amyloid substance with iodine, and with iodine and sulphuric acid ; also with anilin violet (p. 123). (Iddii'ii,. — 1. Boil small pieces of skin, bone, or tendon in water for several hours, skim off the oil on the surface, then filter, and note that the filtrate sets on cooling (pp. 130 and 134). 2. Te.st portions of a hot-water gelatin solution with — ■ {fi') mercuric chloride, tannic acid, and alcohol, and note the slimy precipitates obtained with each reagent ; SYLLAIiUS OF I'liACTICAL COURSE. 68.} (J>) nitric acid, acetic acid, acetate of lead, alum, acetic acid and potassic ferrocyanide, and note the absence of all precipitation (p. 130). Chondrin. — To a solution apply the following tests : — {a) Dilute nitric and acetic acids give precipitates. (h) Tannic acid gives no precipitate, (c) Alum gives a pi-ecipitate. Mucin. — 1. Prepare from tendon and bile as on p. 1.33. 2. Repeat the distinguishing tests for gelatin, chondrin, and mucin given on p. 134:. III. Some Albumin Derivatives. Leucin and Tyrosin. — 1. Prepare from shavings of horn or a mixture of fibrin and pancreas (pp. 136-138). 2. Add a drop of nitric acid to a few crystals of let(cin on a piece of platinum foil, evaporate at a gentle heat; when cool, cover the colourless residue with a few drops of caustic soda, and heat again : a brownish yellow oily drop is obtained (p. 137). A shining brownish yellow residue is obtained with crj^stals of tyrosin, which becomes brown on the addition of caustic soda, par- ticularly when evaporated to dryness (p. 140). 3. Cover a few crystals of tyrosin in a small porcelain dish with a few drops of sulphuric acid ; heat gently and lay aside for half an hour ; then dilute with water, rub up with a little chalk, filter, and evapoi'ate the filtrate to a small bulk ; if necessary filter it again : the clear filtrate gives a violet colour on the addition of a very little dilute solution of ferric chloride. 4. Examine under the microscope the crystals deposited from boiling watery and alcoholic solutions and from ammonia, and compare their appearance with the drawings given on pp. 137 and 139. 5. The ui'ine of a patient suffering from acute yellow atrophy of the liver, malignant jaundice, severe typhus, or small-pox, if it is available, should be examined according to the directions given on p. 137. The leucin will also be readily obtained by evaporating some of the urine to a syrup, which on cooling deposits the leucin in the form of circular yellowish discs ; but if these ai-e separated and then dissolved in boiling alcohol, the solution on cooling will de2:»osit white shining crystalline plates which are insoluble in ether. lY. The Digestive Juices and Digestion. Saliva. — 1. Collect some in a small beaker as in p. 154. 2. Boil a little saliva, and note the slight turbidity produced from 5S4 EXCRETA: THE F.ECES AND VRINE. the precipitation of albumin ; show the albumin also by the nitric or picric acid test (p. 98, 2 and 3). 3. Place a drop of saliva upon a strip of filter paper that has been dried after immersion in an amber-coloured solution of ferric chloride to which a few drops of hydrochloric acid have been added, and note the red stain produced. This is due to the sulphocyanide present in human sali^•a. The stain is removed by mercuric chloride, but not by hydrochloric acid (p. 174). 4. Prepare starch mucilage (p. 163). 5. Convert starch into sugar by the addition of saliva, as in p. 163, 2; then test for starch and sugar, and note the influence exerted by temperature, acids, &c., on the conversion (p. 163). Gastric Juice. — 1. Prepare some artificial juice from the mucous membrane of a pig's stomach (p. 154, a or b). 2. Make a glycerin extract of the dried and finely minced mucous membrane of the cardiac end of a pig's stomach (p. 160, 2), and precipitate the pepsin from this by the addition of absolute alcohol in excess. 3, Carefully repeat the experiments given on pp. 164, 165, and 166 (1 and 2), noting the gradual conversion of the albumin into peptone and the preliminary stage of an acid albumin; then apply the distinguishing peptone tests to the terminal digestive products (pp. 165, 166). Pancreatic Juice. — 1. Prepare the juice according to the directions given on p. 156, .3, a, mincing up a fresh pancreas, covering it with absolute alcohol, and rubbing up the dried mass with washed sand ; the dilute acetic acid is then added, and, after mixing well together for 15 to 20 minutes, the whole is laid aside in a jar and covered with glycerin. Decant the glycerin extract in 3 days and filter. 2. Digest fiagments of boiled fibrin in a one per cent, sodic carbonate solution to which a little of the above glycerin extract has been added (p. 167). 3. Prove a partial decomposition of the peptone formed into leucin and tyrosin (pp. 167, 168, 2, a and h). 4. Add a little of the glycerin extract to some stai-ch mucilage and warm gently (p. 164) ; test for sugar after a few minutes. 5. Mince up some fresh pancreas very fine, and digest it with a little warm water, filter, and neutralise the filtrate, if necessary, \\ith carbonate of soda. (rt) Pi-ub up a little olive oil or melted lard with 3 or 4 times its volume of the watery infusion in a small warm mortar, and note the creamy emulsion formed. (I)) Shake up in- a test tube a few drops of olive oil with a H I'LL A BUS OF PRACTICAL COUIiSE. 585 little of the same neutral infusion, and warm gently, taking care that the temperature does not rise very much. In about 5 minutes or so bring a droj) from the bottom of the tube ujjod a piece of blue litmus paper, and note the red coloration produced, owing to the liberation of the fatty acid by the saponification that has occuiTed (p. 169). V. Bile and Blood, &c. Bile. — 1. Repeat the two experiments given on p. 169, and show the emulsifying of oil by bile, and the more ready penetrability by oils of a membrane moistened with this fluid. 2. Apply Pettenkofer's reaction to some bile in a test tube, as in 1, p. 202 ; also apply the modifications h and d given on the same page. 3. Place a drop of diluted bile on a white plate, and allow a drop of yellow nitric acid to flow into it : at the line of contact a series of coloured bands will make their appearance. 4. Examine with the spectroscope some fresh bile, some altered bile, and a filtered dilute hydrochloric acid extract of bile (p. 203, 3). 5. Prepare the biliary acids according to method l, p. 206. 6. The Pettexkofer reaction should be repeated with some of the biliary salts prepared as above (p. 209). 7. Prepare hiUruhin from biliary calculi according to method 1, p. 212; or, if dog's bile is proem-able, according to method 3, p. 213. 8. Dissolve a little bilirubin in ammonia ; to the solution thus formed add nitric acid di-op by drop, and note the marked play of colours (p. 214), the final product of the reaction being choletelin. 9. Dissolve a little bilirubin in caustic soda contained in a small flask, add some fragments of sodium amalgam, and lay aside loosely corked for 2 or 3 days. Note the gradual disappearance of colour. Decant after a time, and to the decanted liquid add hydrochloric acid drop by drop until a brownish flocculent precipitate of hydrohiliruhin makes its appearance (p. 214). 10. Spread out a thin layer of a caustic soda solution of bilirubin upon a plate, and expose it to the air; the colour will soon become intensely green, owing to the formation of hiliverdin. 11. Separate cholesterin from some powdered pale biliary calculus by boiling it with some spirit to which a few drops of caustic potash have been added ; filter hot, and when the filtiate cools crystals of cholesterin will be deposited. Note that these crystals are easily soluble in ether. (a) Place a few crystals on a glass slide, add to them a drop 586 EXCBETA: THE FA^X'ES AND URINE. of sulphuric acid, mix with a glass rod, and heat the slide gently ; apply a cover gl;\ss, and note under the microscope the carmine tinting of the edges of the crystals (p. 217). {h) Dissolve some crystals in a little chloroform and mix with an equal volume of strong sulphuric acid, when a red solution is obtained, which rapidly changes colour, becoming blue, green, and finally yellow (p. 218). (c) Cover a few crystals lying in a small porcelain dish with a drop of nitric acid, and evaporate to dryness at a gentle heat ; on touching the yellow residue with ammonia a deep red colour is produced, which is not altered by the addition of caustic potash. Blood. — 1. Examine blood under a high power of the microscope, and carefully note the appeax^ance of the corjiiiscles. This should be done w^ith human blood as well as with the blood of a frog, a bird, and a dog or cat ; the blood also should be examined alone and after the addition of sodic chloride solution (0-75 per cent.) 2. Prepare crystals of hcemoglobin from the blood of a guinea pig and of a rat (i and 2, pp. 233, 234), and examine them microscopically (p. 237). 3. Prepare crystals of hanrnin as in method 1, pp. 249, 2G2, and examine them under a high power. 4. Apply the ozone or guaiacum test for haemoglobin (pp. 240, 260). 5. Add a few drops of blood to a small test tube nearly filled with water, and examine with the spectroscope : the two absorption bands between Band E will be seen (pp. 238, 241). 6. Add some reducing agent to the diluted blood in the small test tube, and rapidly examine again, when it will be found that in place of the two stripes a single broad band is to be seen, due to reduced haemoglobin (pp. 241, 238). 7. Now try to get the oxyhsemoglobin bands by spectroscopically examining in a dark room the rosy light that passes between two of the fingers held together in front of a bright light ; and, when this has been accomplished, look in the same way for the single band of reduced haemoglobin after both fingers have had the circulation in them arrested by the application of an elastic ligature at their bases (p. 258). 8. Take a piece of rag that has been stained with blood, scrape the spot, and digest the scrapings in water to which a little ammonia has been added ; examine the coloured solution thus obtiiined with the spectroscope, and look for the absorption bands of oxyha;moglobin SYLLABUS OF PRACTICAL COURSE. 587 (p. 238) ; then add a little reducing reagent and look for the single band of reduced haemoglobin ; note also that by shaking the red solution in the air the two bands reappear. If much ammonia is now added to some of this coloured solution a broad band of alkaline hajmatin will generally be found between c and D. Next add glacial acetic acid in excess to the rest of the red solu- tion, and transfer the mixture to a small stoppered bottle, where it is to be well shaken with an equal volume of ether. The ether soon separates on standing, and it will have a reddish brown colour ; it is then to be decanted into a small glass vessel with parallel walls and examined with the spectroscope (pp. 248, 259, and 261). 9. Leave a blood-stained rag in water for a couple of hours, and note that the ding}^ red solution obtained gives a dirty red coagulum when boiled and on the addition of nitric acid, also that with dilute hydrochloric acid and potassic ferrocyanide a bluish precipitate ap- pears (p. 258). Leave another piece of stained rag in some wat«r in a test tube for an hour or so ; then add a few drops of ammonia and boil, when a dirty grey turbidity is produced, which disappears on the addition of a drop or two of caustic potash, a solution, gi-een by transmitted and red by reflected light, remaining behind. 10. Repeat the six tests for blood given on p. 263 with a single spot of blood on a piece of linen rag. Lymph and Chyle.— \. Examine microscopically some lymph ob- tained by plunging a capillary glass tube into one of the dorsal lymph sacs of a frog. Note the character of the corpuscles, kc. (p. 274). 2. Examine in the same way some of the chyle obtained from the intestine of a rabbit. Note the corpuscles and the molecular basis, and then iiTigate with ether and caustic potash (p. 278). VI. Certain other Secretions and Tissues. Pus and Mucus. — 1. Examine drops of both fluids under a high power, noting the corpuscles, free molecules, and fatty granules, &c. After having looked at them without the addition of any reagent, exairine them in sodic chloride solution {| per cent.), and then liti- gate with dilute acetic acid. In the case of the mucus threads of miicin will be seen (p. 283). Bone. — The practical exercises commencing at p. 307 should now be performed, with the exception of the quantitative analysis. Muscle. — 1. A piece of living muscle from an animal just killed is to be compared with a piece of muscle that has entered into a state of rigor (p. 315). 2. Prepare kreatin from Liebig's extract of maat by process 2, p. 538 L'XCJiETA: mi: F.ECES AND URINE, 319. The crystals, when separated, are to be examined microscopi- cally and their characters noted (p. 318). 3. With a watery extract of Liebig's extract of meat make the analysis givea on p. 329, C. Milk. — Repeat the tests given on pp. 394, 395 (l, 2, 3, 4, and e), first examining a drop of milk under a high power of the microscope, then taking the specific gravity, separating the casein and butter, and detecting the sugar ; also determining the percentage of solids (p. 396, l), and making an approximative determination of the cream present (p, 397, 2, ij). VII. Urine. 1. The reactions and characteristics of normal urine are to be carefully noted in detail (pp. 418-422). 2. Repeat the tests (l-5, 7, and i)for urea given on pp. 426, 427. 3. Determine the urea in urine quantitatively by Liebig's mercuric nitrate method, as detailed on pp. 434-438, and also by its conver- sion into nitrogen gas with Russell and West's or Simpson's appa- ratus (pp. 445-447). 4. Perform the first four tests given for uric acid on pp. 452, 453. 5. Determine approximately the uric acid in a specimen of urine by adding a little hydrochloric acid to it and laying aside for 24 hours (p. 454). 6. Test for indican by acidifying strongly with hydrochloric acid and then shaking up with a little chloroform (p. 475). 7. Determine the sodic chloride present in urine by Mohr's or Folhard's process (pp. 485-486). 8. Separate the organic and inorganic suljihates present in uiiue by method 2 on p. 489. 9. Determine the sulj)hates of urine volumetricallij by means of standard baric chloride (p. 490). 10. Examine a urinary deposit containing uric acid, urates, and phosphates : warm part of it up with a little of the ui-ine, when the urates will disappear, causing a partial clearing up ; now add some acetic acid, and the pho.sphates will dissolve ; filter, and the residual uric acid will dissolve on the addition of caustic potash. Some of tlie deposit sliould be fui-ther examined under the microscope, when tlie yellow, brown, or xeddish-coloured crystals of uric acid will be seen scattered amidst the i-homboidal or triangular ])ri8ms of the phos- phates and the abundant amorphous granules of the urates (p. 492). 11. Separate the phosphates from urine by magnesia mixture (p. 496) and by baryta mixture (p. 437). 12. Determine the amount (f phosjihoric acid by means of stan- SYLLABUS OF PL'ACTICAL COURSE. 589 (lard ur;niic solution (p. 496), and also approximately by Teissier's method (p. 498, III.) 13. Test some alhiminous urine by boiling and by nitric and picric acid (pp. .504-507). 14. Detect the presence of hlood in bloody nrii;e liy the te. t.s on pp. 517, 518. 15. Test some diabetic urine for siKjar by the first four methods given on pp. 523, 524. 16. Estimate the sugar in a specimen of diabetic urine by Fehling's method (p. 76), and also by Bouchardat's approximative method (526, III.) 17. Test for biliary acids and jngment in a specimen of biliary urine (pp. 530-535). 18. Examine a specimen of morbid urine according to the table given on pp. 546-552. VITI. Urinary Deposits fiid Calculi. Deposits. — 1. Examine a little of the deposit according to the method given on p. 554, coniirming the results obtained by the tables on pp. 558-563. 2. Note the action of caustic potash on the deposit when examined microscopically (p. 563). 3. In specimens of albuminous urine casts are to be looked for under the microscope (p. 570). Calctdi. — Several specimens of powdered calculi are to be ex- amined according to the method given on p. 575, and the results obtained confirmed by the table given on p. 577. INDEX. ABN p Abnormal inorganic constituents of urine . 540 organic constituents of urine 541 Absorption spectra of bile . I'JG blood .... 238 hsematin 247 haemoglobin . 241 Acetons 144 Acid, acetic .'58 butyric 3;) caproic . 40 carbolic 43 formic . 38 lactic . 40 oleic 42 oxalic . 41 palmitic 40 propionic 3'.» stearic . 40 succinic 42 valerianic 3i) Adipose tissue 298 Aerobia 387 Albumin yr, detection of . 102 general tests 98 of egg . 104 preparation of a S( jlution of . 97 separation of , 102 Albuminates . 100 acid '. 101, 117 , 122 alkali . . 101 , 111 Albuminoids 89 Albuminous urine 503 amount of . 504 characters . 503 pathology of . 512 quantitative estimation o e the albumin in . . 509 by Bodecker's method 511 by clinical method of de - posits . . 510 by Esbach's method . 510 by polariscop e . 509 AMY PAGE Albuminous urine — contin ueil. quantitative estimation of the albumin in, by Roberts's dilution method . . .511 by SCHERER's method , 509 by Tanret's „ .512 tests .... 502, 546 to separate albumin from . 508 Albumins, animal . . .26 vegetable . . .27 classification of . . .103 albuminates . . .114 casein . . . 115, 385 coagulated albumin . 124 egg albumin . . . 104 fibrin . . . .113 fibrinogen . . .108 fibrinoplastiu . .109 globulin . . .106 lardacein . . .122 metalbumin , . .124 myosin . . . .107 paralbumin . . .124 peptones . . .119 serum albumin . . 103 vitellin .... 106 in blood serum . . . 226 separation of . .254 table identifying the . .125 Albuminuria . . . .512 Albumose ..... 117 Alcohol, role of . . . .31 Alcoholic fermentation . . 143 Alcohols, chemistry of the . . 34 Alkapton ..... 529 AUantoin ..... 459 Alloxan ..... 457 Alloxantin ..... 457 Ammonic sulphide ... 3 Amniotic fluid .... 278 Amyloid substance . . . 122 tests for . . , .123 to extract .... 123 592 llsDEX. AMY P.^GE BUT ] Amyloses .... 44 Blood Anasarca .... 280 chemical composition . Animal albumins 26 coagulation of . . . Antiseptics .... 147 corpuscles .... in surgery 148 difference in, in different Apparatus .... 3 parts .... Aqueous humour . 270 , 347 distribution .... Arabin .... 59 estimation of constituents . Ascitic fluid 280 albumins ash and water Bacteria . . . 146 coi-puscles Benzoic acid 463 fats .... derivatives . 463 fibrin . . . . properties . 463 salts .... Bile 196 sugar .... absorption spectrum 196 , 203 urea .... actions 200 uric acid amount 196 ferment . . .111, chief constituents 198 functions .... composition . 197 gases of ... . effect of food on . 199 influence of sex, age, food, in digestion . 1.52 &c., on composition . pathology of 204 microscopic constituents properties 196 pathology of role of . 200 alterations in disease secretion 197 table showing dis- solids 198 eases . .source of constituents . 201 types of variations tests and reactions 201 physical characters to analyse 204 practical exercises for the to detect, in vomited matters 204 preparation, separation, Biliar}' acids 206 &c., of constituents . derivatives . 210 quantity . . . . preparation . 206 spectroscopic examination . tests for 202 , 209 tests calculi .... 205 Bloody urine .... examination of 576 properties of . . . pigments 212 tests for . . .517, methods forseparat iono ' .532 Bone urine . . . • 5.30 analj'ses and anah tical exer- pathology of . 535 cises properties 530 composition of . . . tests for 530 as affected by age, &c. . biliary acids . 5.30 ,549 general constitution pigments . 531 , .548 marrow of . r.ilicyanin . . . • 214 pathology . . . . r.ilifulvin . 212 Brain Bilifuscin . . • • 212 chemical composition . Bilihumin . . • ■ 213 isolation of constituents Bilii)h;ein . 212 (Thudichum) . I'ilinibin 212 ultimate analysis . derivatives and cliaractor white and grey substance istics 214 compared preparation . proper! ies 212 Brenzcatechin sulphonic acid 213 Brunner's glands Bilivcrdin 215 Burettes . . . . . preparation . 215 Butter properties 215 PAOE 219 222 250 225 230 221 263 265 264 266 265 265 264 268 267 267 256 219 227 231 221 268 269 271 268 219 254 221 258 257 516 516 5.^0 303 307 304 305 303 306 307 331 332 343 334 335 479 195 4 391 IXDEX. 6J)3 CAB DEO V.KdV. PAGE Cabbages .... 28 Choletelin 214 Calculi 571 Cholic acid . . . . . 210 biliary .... 57(5 Chondrin . . . . . 130 clas.sificatioii 576 derivatives . . . . 131 comparative frequency 571 preparation . . . . 130 forin.s and characters . 571 projjerties . . . . 131 Iiroliminary examination of 575 tests . . . . . 131 .salivary 176 Chondrogon . . . . 301 table for identifying . 576 Chromojihane . . . . 345 urinary 571 Chrysophanic acid in urine, to Cane svifi:ar .... 57 detect 543 Carbohycl/ates •M) Chyle 150 ,275 chemistry of U Composition . . . . .276 Carbonic acid expired 368 examination of . . , 277 circumstances affecting the properties . . . . 275 amount 369 Chyluria 538 Camin .... 322 Chyme . . , .150 180 Cartilages .... 300 Coilee 29 classification of :500 • Coagulated albumin . 124 composition of 30] Coagulation of blood . 2.50 Casein 1 1 ."> , 3H5 theories as to causes 251 digestibility of 392 of milk . . . . 386 Casts, urinary 566 Collagens 128 classification of 567 Colloids 6 examination of 569 Connective tissue 297 significance of 570 classification of . 299 Cataract in lens . 2;'6 composition of . . . 299 Cement of connective tissue 299 structural elements 297 of teeth 311 Contagium . . . . . 147 Cerebral fats 340 Conversion of starch into Cerebric acid 340 sugar. . . 163 173 Cerebri n .... 340 by intestinal juice 164 composiiion . 342 by pancreatic juice 164 preparation . 341 by saliva 163 properties 341 of albumin into peptones 164 Cerebro-spinal fluid 279 by gastric juice 164 Cerebrote .... 837 , 340 by pancreatic juice 167 Charcot-Neumann crystals 358 Cornea 348 Cheeses 26 Corpuscles of blood 225 Chemicals . . . . . 1 enumeration of, Gower's . 267 Chlondes of urine 480 Malassez' . 266 amount . . . . 481 separation of . . . 255 pathological alterations 482 Cresol sulphonic acid . 479 tests 482 Crystallin 106 volumetric determination . 483 Crystalline lens . . . . 295 Arnold's process 487 Crystalloids . . . . 6 Folhard's „ 485 Cystin 556 LlEBKJS „ 483 calculi . . . . . 574 Mohr's ,, 484 preparation . . . . 556 ChLjrine water . . . . 2 Cysts :— Chloroform in urine, to detect 542 echinococcus 281 Cholalic acid . . . . 210 ovarian . . . . 281 Cholepyrrhin . . . . 212 strumous . . . . 281 Cholesterin . . . .216 310 calculi . . . . . 575 Decantation . . . . 7 preparation . . . . 216 Decomposition processes 144 properties . . . . 216 Degenerations . . . . 379 tests 217 amyloid . . . . 380 Q Q 594 INDEX. DEa Degenerations — continnrd. calcareous colloidal fatty . mucous pigmentary Dentine Deposits, action of potash on classitication of . urinary Desiccation .... Detection of blood Dextrin .... preparation . tests .... varieties Dextrose .... Diabetes mellitus artificial production of Diabetic urine properties quantitative sugar in Dialysers Dialysis Diastase Diet, mixed . Dietaries, MolesohotT Playfaie . Easke. Digestion of albumins . GAS estimation of . 150, 164, 179 . 168 150, 168, 173 of fats . of starches pathology of Digestive action of secretions ferments fluids, amount of . Disinfectants Distillation .... Dyslysin .... Egg albumin and serum albumin con trasted Elasticin (elastin) properties Enamel .... Encephalin . . . • Epithelial urinarj' depcsits . Epitheliums Equilibrium between ingestu and egesta .... Ethyl alcohol to determine quantitatively to separate . Evaporation tAGE . .381 . 379 . 379 . 380 . 380 . 312 . .563 . 552 . 552 . 7 . 259 . 47 . 48 . 48 . 48 . 60 . 527 . 528 . 522 . 522 525 6 .5 1.58 23 24 25 24- 149 167, 191 191 191 186 153 157 153 147 9 206 101 97 135 136 312 341 561 292 20 35 36 35 10 Excretion Eye . PAGE . 404 . 344 F^CES analysis of . composition .... gases of .... in pathological conditions . inorganic constituents . ultimate percentage compo- sition .... Fats constitution .... destination .... detection of . determination digestion of . . . 168, distribution in the body properties .... sources of, in the organism . tests . . . . . Fatt}^ acids ..... bodies, to separate, from urine. . . . . degeneration Fermentation test for sugar composition .... Fermentations classified Ferments ..... division of . Fibrin, decomposition products . estimation of . . . generation of . . . preparation of clot Fibrinogen . Fibrinoplastin Filtering apparatus Filtration . Foods .... amount required . classification of . definition of . nitrogenous . salts required in . uses of . value of Fruits .... Fusible calculus . 400 401 401 402 404 402 402 83 83 87 88 88 191 87 85 85 87 38 539 379 66 112 142 141 142 253 265 112 256 256 256 11 10 17 18 24 17 25 12 18 19 28 573 403 402 187 275 317 199 227 changes in, in respiration 229 no, 109, 23 GasEs in the large intestine in the small intestine in the stomacU of lymph of muscle of the bile . pf the blood . IXDILX. oOo GAS PACK Gases — rnutiinied. of the milk .... 384 of tlio saliva . . .171 of triinsudations . . . 281 Gastric juice . . . 150, 177 acid of 1 Sfi nrtiticial .... 1.54 chemical composition . .177 conditions affeci ing . .184 digestive action . . . 17!) quantity . . . .177 secretion of . . . .185 theories as to action . . 1 80 Gelatin 128 chondrin, and mucin con- trasted . . . . \M derivatives . . . .129 preparation . . . .128 properties . . . .129 tests 130 General digestive action of the secretions . , .153 Germ I lieory of disease . .146 Globulins lOfi Glutin 128 Glycerin 36 combinations . . 3(5 detection . . .37 phosphoric acid . . . 3i{8 preparation . . . . 3G Glycin 463 Glycocholic acid .... 208 Glycocin 463 Glycocol 463 derivatives .... 464 preparation . . . .461 Glycogen 49 conversion into sugar . . 53 destination .... 52 in liver ..... 354 in muscle .... 354 preparation .... 50 properties . . .51 sources . . . . .51 tests 56 where found . . . .49 Glycosuria 527 Gmelin's test for biliary pig- ments .... 203, 532 Grape sugar 60 combinations . . .61 decompo.silions . . .62 destination . . . .63 origin in organism . . 62 preparation . . . .61 properties . . . .60 quantitative determination by Feh ling's method . 75 by fermentation pnx-ess 79 IIYD PAGE Grape sugar — continued. quantitative determination l)y Johnson's method 525 by ivNAPf's „ . 78 b}' polarisation ,, .71 by RoBKKT.s's „ . 80 by Sachsse's „ . 78 separation of . . .69 tests 63 Guanin ..... 323 ILematin 216 derivatives .... 247 j)reparation .... 246 Hamiatoidin .... 248 Ha'oiatoporphynn . . . 240 Hajmaturia . . . . .516 pathologj' . . . .517 tests for . . , .517 Hiemin 248 preparation .... 249 tests .... 249, 262 Hfemochromogen . . . 239 Haemoglobin .... 233 crystals 237 derivatives .... 239 estimation of . . . 242 pathologj' . . .245 preparation .... 233 properties .... 236 proportion in blood . . 240 spectra 241 tests 240 Ha^moglobinuria .... 520 Huemolutein .... 378 Hairs 294 Hen's egg, composition of . .104 Hepatic blood .... 230 cells 354 Hippuric acid .... 460 derivatives . . .463 benzoic acid . . . 463 gh'cocin. . . .463 in urinarj' deposits . . 563 origin and amount formed . 460 preparation .... 461 jroperties . . .461 tests 462 to detect, in urine . . 462 Histological chimges in active peptic cells . . .182 in pancreatic cells . .183 Histozym 144 Homocerebrin .... 341 Horny structures . . . . 294 Hvdric suljihide .... 3 Hydrobilirubin . . . 215, 468 prep.nration .... 469 properties . .470 Q g 2 696 INDJEX. HYD Hydrocele fluid . . 281 HjTJOxaQthin . 320 ICTERIS . 535 Incinenitiou . 11 Indican . 472 derivatives . . 477 estimation . . 475 preparation . . 473 quantity . 474 tests 475, 551 Indigo blue . . 477 white . . 477 Indol .... 403, 477 preparation . . 403 properties . 404 test f or . . 168 Inosic acid . . 322 Inosit .... . 81 preparation . . 81 l^roperties . 82 tests . 83 Intestinal conci-etions . . 405 fluxes . . 281 juice 152, 194 actions . 195 artificial . . 156 quantity . . 194 Iodine solution . 2 Iodoform in urine, to detecl I '. 542 Isatin .... . 478 Kephalin . . 338 Keratin . 293 Kidneys . 360 Kreatin . 318 derivatives . . 319 preparation . . 319 Kreatinin . . 465 amount . . 465 characteristics and test s . 466 combinations . 466 preparation . . 46.-> properties . 466 Kryptophanic acid . 480 Lactic acid fermentation . . 143 Lactose 58 preparation . . . .58 to detect, in milk . 59, 395, 39K Lardacein 122 Lecitliin 336 and fats, separation of, from blood corpuscle.'j . . 255 characteis and relations . 336 preparation .... 336 properties .... 337 MIL Leucin .... pathology preparation . properties tests to detect in urine . to separate . Liebig's extract of meal of . Litmus solution , Liver .... ash of . composition of ferment pathology of Lungs .... calculi of concretions of sputa of tubercle of . Lymph. amount. ash composition . gases properties Lymphatic glands PAGE . 135 . 138 . 136 . 136 137, 167 . 137 . 138 , analysis . 329 2 . 353 . 354 . 353 . 162 . 355 . 362 . 363 . 363 . 363 . 362 . 273 Magnesia mixture Maintenance of body weight Maltose Marrow Meconium . Melanin Melituria Metalbumin. Metallic salts in urine, detection of ... . Mcthicmoglobin . Methods fordetecting some of tlie occasional heterogeneous con- stituents of urine . . . 542 Jlicrozymas . . . . .145 Milk 3S1 alterations in, due to age, food, &c 389 amount .secreted . . . 382 analysis of . . . .394 qiuditative . . . 394 quantitative . . . 396 ash of 383 coagulation of . . . 386 ciim]i()sition of . . . 382 condi used milk . . . 384 cow's milk .... 385 gases of .... 384 jiatliological alterations in . ;>93 preservation of . . . 392 273 271 275 273 360 2 15 59 3( i6 403 3.50 521 124 544 239 INDEX. 507 MIL i'A(ii: PlIO PAUK Milk rotitinucd. Nitrogenous foods 25 rel;itive value of (liffereiif Non-striated muscle . 316 kinds of 384 Normal solutions . 12 substitutes for woman's Nuclein 286 milk .... 3t)2 of spermatozoa 376 uterine milk . 3K1 Nutrition 13 woman's milk 385 IMiLLON's reagent 2 Olein .... 85 MoU'Ciilar base of chyle 27(; Organic acids .37 Mol^'bdate of ammonia 1 Osmose 6 Morbid urine, table for examina- Ossein .... 307 tion of ... . r,4r> Ovarian cysts 281, 378 Morphine, to detect, in urine 544 Ovary .... 377 Mucin 132 Oxalate of lime calculi 572 derivatives . . . . 133 in urinary deposits 554 565 preparation . . . . 132 Oxidation the source of energy . 16 properties . . . . 133 Mucous fermentation . 144 Palmitin . 84 Mucus 287 Pancreas 356 buccal 288 Pancreatic juice . 15l' 187 composition . . . . 289 artiticial 155 intestinal . . . . 288 chemical composition 188 properties . . . . 288 dige.stive action . 191 uterine . . . . . 288 ferments 161 189 vaginal . . . . . 288 quantity 188 vesical . . . 536 secretion 188 Murexid . . . . . 458 Parabanic acid 459 Muscle 313 Paralactic „ 324 changes occurring in . 314 Paralbumin . 124 378 composition . . . . 316 Pepsin .... 159 extractives . . . . 318 preparation . 159 gases of . . . . 317 properties 160 general analytical methods . 326 Peptic digestion . 181 inorganic constituents . 324 rapidity of 184 juice . . . . . 108 and tryptic digestion com- nitrogenous bodies in . 317 pared 193 pathology of . . . 325 Peptones . 94 119 plasma, preparation of 107 composition . 94 120 properties of . . . 313 destination . 151 rigor mortis . . . . 315 pancreatic . 189 serum 108 preparation . 120 sources of energy . 325 properties and reac tions 121, INIushrooms . . . . . 28 165 Myelins 338 salts of the . 120 Myosin 107 Pericardial fluid . 279 Plienol .... 43 543 Naphthilamine 168 sulphonic acid 479 Nephrozymase . . . . 480 Phosphates of bone 304 309 Nerve 830 of urine 491 analysis . . . . 334 amount excreted 493 chemical composition . 332 variations in 493 chief constituents 332 origin of 492 general structure . 331 pathological alterations 499 grey and whitish matter 332 335 quantitative estimatio n by Neurin 339 uranic phosphate 496 preparation . . . . 339 by molybdate of am- properties . . . . 340 monia 498 Neuro-keratin . . . . 342 by Teissier's met lod . 498 593 INDEX. PHO I'hosphates —coiitin ued. quantitative estimation of lime and magnesia phos- phates 499 reactions and tests 495 Phosphatic diabetes 501 calculi .... 573 Phrenosin .... 342 Pigment of skin . 350 retinal .... 346 m-inary .... 467 Pigments, relations among the soluble .... 215 Pipettes .... 4 Plasma of blood . 226 256 Plasmin of Denis 111 Pleuritic fluid 280 Polarisation . 70 Portal blood 230 Potassic bromide in urine 542 iodide in urine .542 Potassio-mercuric iodide 50 Pressure bottles . 54 Proportions of the chief ti ssues of the body . . . 21 Prostatic calculi . 376 575 secretion 375 Protagon 337 preparation . 337 relations 837 Protarain 377 Proteids 89 characters 89 combinations 91 composition . 90 derivatives . . . 91 destination of 93 terminal products 95 where found . 89 Protein reactions 96 Protoplasm of pus corpusch JS 286 Ptyalin 158 I'urpurate of ammonia 468 Purpuric acid 458 Purpurin 468 Pus .... 283 analyses of . 284 corpu.scles 286 in urine 537 to analyse 285 Putrefaction 145 Pyin .... 287 Pyloric juice 177 I'yocyanin . 287 J'yoxan those 287 J'yrocatechin 529 PAGK 407 240 388 365 365 Quinine, to detect, in urine 343 SER Reaction of urine Reduced hajmatin Rennet ..... Respiration ..... changes in respired air circumstances affecting the respiratory exchanges . 369 alterations of pressure, disease, &c. . . 373 food, hunger, period of day , . . . 370 rest, &c. . . . 369 sleep, sex, age, size . 371 Retinai 344 Rigor mortis .... 315 Saccharimetee . . .72 yaccharimetry . . . .73 Saccharoses . . . .44 Salicylic acid, to detect, in urine 543 Saliva 154, 169 chemical composition . .170 functions . . . .173 quantity . . . .173 parotid .... 171 pathology of . • . .175 reactions of . . • . .174 sublingual .... 172 submaxillary . . . 1 72 stimuli to secretion of . 172 Salts, distribution of, in body . 22 of the alkalies in urine, to estimate .... 501 of the blood serum, distribu- tion of . . . .254 Santonin, to detect, in urine . 543 Sarkin 320 preparation . . . .320 properties . . . .321 r(!latioDS . . . .321 Sarkosin 319 preparation .... 320 properties .... 320 Schizomycetes .... 146 Scybalaj 405 Sebaceous secretion . . . 351 Sediments, urinary , . . 552 conditions of occurrence . 564 Semen ...... 376 Septic poisons .... 147 Serine 103 Serosities 278 amniotic fluid . . . 278 atpi'ious humour . . 279, 347 cfMX'ljro- spinal fluid . . 279 dropsical fluids . . . 280 echinococcus cyst . . 281 hydrocele fluid . . .281 LMJIJX. V.)i) SER UUE Serositics— cotiti/iiicd. Sulphates of urine — coutinvcd. intestinal lluxes . 281 estimation of . . . 489 ovarian cysts 281 origin of . . . 487 pericardial fluid . 27i) tesis 489 pleuritic lluid 280 Sulphocyanide, determination of 175 strumous cyst 281 in saliva . . . . 174 synovial fluid 279 in urine . . . . 540 table of ... 282 Sulphuretted hydrogen 3 Serous fluids, methods for the Suprarenal capsule 358 examination of 290 Syllabus of practical course 579 Serum of blood . 22G Synovia . . . . . 279 Skatol 404 478 Syntonin .... 108 , 117 Skin a48 Sweat ...... 349 patliology of :{.-32 amount . . . . 350 Slaked lime 1 composition . 349 Sonnexschein's method foi iso- lating alkaloidal principles 344 Tartar of teeth . 176 Specific gravity . 13 Taurin ...... 211 of urine Spectroscopic examination l)loocl of 2;'J8 412 201 preparation . . . . properties . . . . 211 211 bile .'.'.'. Spermatin .... Spernuitozoa 196 203 397 H76 Taurocholic acid . quantitative determination . Tea •Tears 208 210 29 347 Spleen .... composition of functions 3.56 357 356 Teeth Testicle 311 376 pathology Sputa ..... Starch .... 357 363 45 Thymus gland Thyroid Tissue changes and interchanges 359 359 16 Tourmaline jjlates Transudations . . . . in albuminuria pathological 70 conversion into sugar . solution tests .... Starvation .... 46 2 47 33 278 281 280 results of . . . Stearin .... 33 84 physiological table of . . . . 279 282 Stearoconote 340 Trj-psiu 189 Stercobilin .... 215 Tyrosin . . . . . 139 S'rumous cyst 281 preparation . . . . 138 Sugar, cane .... 57 properties . . . , 139 tests .... 140 , 168 grape .... 60 in normal urine . 69 in the liver, demonstration of 54 Uraemia 433 in the urine . 521 Uramil 458 milk .... 58 Urates . . . . . 155 pathology of .527 deposits of . 457 tpiantitative estimation 526 properties of . . . 4.56 by BOUCHARDAT'S den- Urea 422 sity method 526 amount excreted . 430 by circular polarisation 526 influences affecting 430 by DuHOMSfE's method 526 characters . . . . 423 by Fehlixgs method . 75 chemical relations 424 b}^ Johnson's picric combinations 424 acid method 525 decompositions 425 tests for 522, .547 derivatives . . . . 426 to s(!parate . 526 detection in blood 428 Sulphates of urine 487 preparation . . . . 423 amount 488 ipiaiititative determination . 434 GOO IXDL A'. UEE I'.MIK ZYM I'AGE Urea — continved. Urinnry ^\gmG\V %~ eoDfi inird . quantitative (letermination purpurin ■JOS by Bunse.n's and other urobilin 408 methods 448 detection of . 470 by conversion into ni- urochrome 471 * trogen gas 442 preparation . 471 KXOP and HuF- uromelanin . 471 ner's method 44. S urorubrohasmatin . 468 modifications of the uroxanthin 468 gas method . 447 sediments . . . . 552 EUSSELL and tables for examination West's method . 445 of . . . 554 , 558 Simpson and Urine ..... 406 O'Keefe's me- ash and solids, to obtain 414 thod . 44(1 colour 4C9 Liebig's mercuric ni- constituents . 415 trate method 434 gases of . . . . 417 modifications of 4:-58 general characters 406 nece.«sary corres- quantity of . 410 tions . 4:5S in children . 411 reactions and tests 42(i reaction of . 400 source and seat of for- reactions and characteristics 418 mation 428 solids, amount of . 418 Uric acid 448 specific gravity 412 combinations 451 to estimate acidity of . 408 decompositions 451 ti'ansparency 410 derivatives . 457 Urobilin, defection -of . 470 allantoin 459 preparation . . . . 470 alloxan . 457 proiaerties 470 alloxantin 457 Urochrome .... 471 murexid 4.58 preparation . 471 parabanic acid 459 Uromelanin 471 purpuric ,, 4.58 Uterine milk 381 uramil . . . . 458 pathology of . . . 455 Vegetable food 29 preparation . . . . 4.50 Venous blood 230 properties . . . . 4.50 Vision purple 346 quantity excreted 449 Vital capacity 368 tests and reactions . 4.52 550 Vitellin .... 106 to determine its presence and Vitreous humour 347 amount 453 Garrod's method 4.54 Wasting diarrhoea . 34 Heintz's „ 454 Water in the organism 21 Ludwig's „ 454 Petit's „ 4.54 Xanthin .... 321 Urinary calculi . . . . 571 calculus 574 tables for examination preparation . . . 321 of ... . 575 properties and tests 321 casts . . . .562 500 classification of 507 Yeast in fermentation 68 examination of . 509 influence of acids on activity 68 pathology of . 570 pigments 407 Zymogen .... 189 Sjiollijicoode rac- tiiioners and students, and establishes for its author a high position in the department of science and practice which his handbook illus- trates.'— BiUTIsii Medical Journal. 'This is a sound jiractlcal guide to the treat- ment of bodily deformities, based evidently upon personal observation and experience We can cordially recommend the work as a guide to busy praclitioners.who will find in it just what they want, clearly set forth and illustrated." London Medical Record. Loudon: SMITH, ELDER, & CO., 1-5 Waterloo Place. SMITH, ELDER, & CO.S PUBLICATIONS. A SYSTEM nf OBSTETRIC MEDICINE and SURCrERY: Thporctical and Clinical, for the iStnilent nnd tlie PractitioiuT. Jiy ItunKirr Barnes. M.I)., Obstetric Physici.Tii to St. Georifo's Hospital, Coiisulling Plijsician to the (,'hclse.i ItfRpital for \Voinen, &c. ; and Kaxcoikt Baiimcs. M.O., Pliysician to tlie Royal Maternity Chsuity and totfe Jiriiisli Lyinfr-in Hospital, Assi-tant Obstetric Physician to tlie Great Northern Hospital, Physician to tlio Clielsea Hos]iital for Women. The Section on Embrjology contributed by Professor M11..NE8 Maushalu Vol. I. 8vo. profusely Illustrated, price 18.t. 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