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One among the most distinguished of tue Medical faculty, in noticing the great value of this work to the student and practitioner, says, " We therefore hailed with no incon- siderable pleasure the appearance of the Dispensatory of the United States, convinced from our knowledge of its authors that it would prove a most valuable addition to our Medical literature. We have not been disappointed in these expectations, and feel fully persuaded that it will take the first rank among works of this character." The editors of the Journal of Pharmacy observe, as regards the merits of the work, "We recommend it most cordially to the Medical fraternity, to the practical pharma- ceutist, and especially to the diligent perusal of the student of medicine or pharmacy." 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Professor of Materia Medica and Obstetrics in the Jefferson Medical College, Philadelphia, 2d edi- tion, improved. This is one of the most valuable works on the Practice of Medicine, that has ever issued from the American or English Press. The distinguished editor of the North American Medical and Surgical Journal, speak- ing of this work, says, — "The work of Dr. Eberle is confessedly one of very great merit. It does much credit to his industry and learning, while it places in a yery fa- vourable point of view his abilities as a practitioner. The talents, industry, and variety of research necessary for the production of a system of Practical Medicine, are possess- ed by few, and when we say, as we do with great candour, that the Treatise before us will bear a very favourable comparison with any modern work of the same class, while it is far superior, as well in regard to the soundness of its pathological views, generally speaking, as to the excellence of its therapeutic precepts, to the more popular of the English systems, we confer upon it and its author no mean praise." The April No. of Johnson's London Medico-Chirurgical Review, speaking of this work observes, " That this is a very respectable compilation ; in fine, superior to Tho- mas's Practice of Physic in this country." Although designed chiefly for professional men, it will be found a valuable practical manual for private or domestic reference. If heads of families were to purchase and MEDICAL WORKS. consult this work instead of the empirical and in many respects misleading compounds so common, they would have the satisfaction of being assured, that nothing but sound and well tested practical directions would be offered them, — at the same time they ■would acquire correct notions concerning the character and systems of diseases. Every person of good understanding may comprehend the practical rules laid down in this work. To render this invaluable work particularly useful, as a work of reference for family use, a glossary is added of the technical terms used in the work. A TREATISE OX THE MATERIA MEDICA and THERA- PEUTICS, in 2 vols. Third edition, improved and greatly enlarged. By John Eberle, M. D., Professor of Materia Medica and Obstetrics in the Jefferson Medical College ; Member of the American Philosophical Society; Corresponding Member of the Medico- Chirurgical Society, &.c. THE PHARMACOPOEIA of the United States, revised edition, bv authority of the National Medical Convention, which met in Washington, in January, 1830, in 1 vol. Svo. All persons ordering this work will please say " The Philadelphia edition of 1831." To all country Practitioners and Apothecaries, a copy of this work is indispensable ; not one dose of medicine should be put up unless by the prescriptions contained in it. The government has taken a full supply for the Medical Staff of the Army and Navy of the United States. Resolved, As the opinion of the Philadelphia College of Physicians, and the Phila- delphia College of Pharmacy, that the United States Pharmacopoeia of 1830, as revised by the National Medical Convention which met at Washington, in January, 1830, de- serves the confidence of the Medical and Pharmaceutical Professions; and for the pur- pose of promoting uniformity in Pharmaceutical formula:, the two Colleges do agree to adopt the said work as a standard of Pharmacy, and recommend to their respective members to conform to its directions. THOMAS PARKE, President of the College of Physicians. DANIEL B. SMITH, President of the College of Pharmacy. Philadelphia, March, 1832. VELPEAU'S ELEMENTARY TREATISE OX THE ART OF MIDWIFERY, or the Principles of Toxicology and Embryology, in 1 volume, Svo. Translated from the French, by Charles D. Meigs, M. D. Member of the College of Physicians, Sec. &c. 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With considerable additions and improvements, adapted particularly to this country, by Thomas M. Smith, Veterinary Surgeon, and member of the London Vete- rinary Medical Society, in 1 vol. 12mo. The publisher has received numerous flattering notices of the great practical value of this work. The distinguished editor of the American Farmer, speaking of the work, observes — " We can not too highly recommend this book, and therefore advise every owner of a horse to obtain it." CONVERSATIONS ON CHEMISTRY, in which the Elements of that Science are familiarly explained and illustrated by Experiments and Engravings on wood. From the last London edition. In which all the late Discoveries and Im- provements are brought up to the present time, by Dr. Thomas P. Jones. All preceptors who have a sincere desire to impart a correct knowledge of this im- portant science to their pupils, will please examine the present edition, as the correc- tion of all the errors in the body of the work renders it very valuable. The eminent Professor Bigelow of Harvard University, in noticing this work, ob- serves, "lam satisfied that it contains the fundamental principles and truths of that Science, expressed in a clear, intelligible, and interesting manner. The high charac- ter of the author, as a lecturer, and as a man of Science, will, I doubt not, secure for the work the good opinion of the public, and cause its extensive adoption among Se- minaries and Students." Dr. Pattison's Lecture. Dr. Baudelocque on Puerperal Peritonitis. Miner & Tully on Fever. The Physician's Pocket Synopsis, by Bart- let. Brown's Elements of Medicine. Gregory's Practice. Ducamp on Retention of Urine, &c. Denman's Midwifery. Desruelles & Guthrie on Venereal Dis- ease. 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GROSS, M. D. PHILADELPHIA: JOHN GRIGG, NO. 9, NORTH FOURTH STREET. 182S. Eastern District of Pennsylvania, to wit: BE IT REMEMBERED, that on the twenty-seventh day of Septem- ber, in the fifty-third year of the Independence of the United States of America, A. D. 1828, J. Grigg of the said district hath deposited in this office the title of a book, the right whereof he claims as proprietor in the words following, to wit: "A Manual of General Anatomy, Containing a Concise Description of the Elementary Tissues of the Human Bodv. From the French of A. L. J. Bayle and H. Hollard. By S. D.' Gross, M. D." In conformity to the act of the Congress of the United States, entitled " An act for the encouragement of learning, by securing the copies of maps, charts, and books to the authors and proprietors of such copies during the times therein mentioned;" — And also to the act entitled "An act supplementary to an act entitled 'An act for the encourage- ment of learning by securing the copies of maps, charts, and books to the authors and proprietors of such copies during the times therein mentioned, 5 and extending the benefits thereof to the arts of designing, engraving, and etching historical and other prints." D. CALDWELL. Clerk of the Eastern District of Pennsylvania. Hkkrfcal CoHccSon TO GEO. M'CLELLAN, M. D. PROFESSOR OF ANATOMY AND SURGERY I3J THE JEFFERSON MEDICAL COLLEGE, Whose great skill and extensive knowledge in the va- rious departments of the Medical Sciences, add lustre to the profession, and whose integrity of principle and pri- vate virtues are not less distinguished than his professional attainments, the following pages are inscribed as a testi- mony of the esteem, the gratitude and respectful attach- ment of his friend and pupil, S. D. GROSS. Philadelphia, August, 1828. The Reader is requested to correct the folloiuing ERRATA. Page. Line. 2, 30, for lymph, read chyle. 9, 1, for spungy, read spongy. 17, 5, for anasarca and oedema, read oedema and anasarca. 19, 10, for recrementitial, read excrementitial. 31, 7, for carachus, read urachus. 84, 10, for consists, read consist. 86, 11, for desication, read desiccation. 120, 24, for vertebra, read vertebrae. 163, 28, for on dividing of the ganglia, read on division of the ganglia. PREFACE. General Anatomy is a science of comparatively modern date; and like every other great and important improve- ment, it has gradually arrived at its present degree of per- fection. To Bichat, no doubt, is due the honour of having first established this branch of anatomy into a science, and the work which he has left us upon this subject, is at once an imperishable monument of his great talents and of his ingenious and profound researches. Notwithstanding the importance of a thorough know- ledge of General Anatomy, it is a fact, that it has received less attention in this country, than perhaps in any other part of the globe to which medical science has hitherto found its way. For the truth of this assertion, we appeal to the candid and high" minded student, whether during the course of his attendance upon lectures, he has heard his anatomical professor enter into any minute details on this important branch of his professional studies, or whether he has not merely glanced at it, or perhaps said nothing upon the subject. We shall not stop to inquire into the cause of this neglect; but we fondly anticipate the day when this evil shall be remedied; and ardently hope that the science of general anatomy may soon receive that share of attention from the physicians of this country, which it so justly merits, and which it at present receives in the medical schools of Europe, and particularly in those of France and Germany. VI PREFACE. We have been aware that a work on general anatomy is much wanted in this country; and with these impressions we have undertaken the translation of the Manual of MM. Bayle and Hollard; in doing which we have not scrupled to make a few alterations, but the deviations from the original are trifling. If, however, we have failed in some instances, in doing justice to the original, we ask only the indulgence of those who have the liberality and can- dour to receive with impartiality whatever is intended to facilitate the progress of their studies, while we neither ask nor care for the indulgence or liberality of sentiment of those of an opposite character. S. D. GROSS. INDEX. Page. Dedication, - - , - - - - iii Pheface, - - - - - - - " - y INTRODUCTION, --....-X CHAPTER I. Celluxab. System, - - - - ... 9 Section 1. Cellular tissue, properly so called, - - ib. Pathological Anatomy, - - - 16 Bibliography, - . - - - 19 Section 2. Adipose tissue, - - - -20 Pathological Anatomy, - - - 24 Bibliography, - - - - - 25 1 . CHAPTER H. Vascuiar System, - - - - - - 26 Section 1. General Observations, - ib. Pathological Anatomy, - - - 31 Section 2. Of the Arteries, - - - - 32 Pathological Anatomy, - - - 38 SectionS. Of the Capillary vessels, - - - 42 Pathological Anatomy, - - - 47 Section 4. Of the Veins, - - - - - 49 Pathological Anatomy, - - -55 Section 5. Of the Lymphatic System, - - -57 1. Of the Lymphatic vessels, - - - ib. 2. Of the Lymphatic Ganglia, - - - 63 Pathological Anatomy, - - - 64 Bib liography of the Vascular System, - - 6j VI 11 INDEX. CHAPTER III. Of tub Ssnoca Ststkh, - - - - - - 68 Section 1. General Observations, - - - ib. Pathological Anatomy, - - 71 Section 2. Of the Sero-splanchnic Membranes, - - 74 Pathological Anatomy, - - - 77 Section 3. Of the Synovial Membranes, - - - ib. Pathological Anatomy, - - - 81 Bibliography of the Serous System, - - 82 CHAPTER IV. Of the Fibrous System, - - - - - - 84 First Division. Of the Fibrous System, properly so called, - ib. Section 1. General Observations, - ib. Pathological Anatomy, - - - 87 Section 2. Of the organs composing the Fibrous System, properly so called, - - - - 88 Article 1. Of the Fibrous Ligamentous organs, - ib. § 1. Of the Ligaments, - ib. §2. Of the Tendons, - - - 90 Article 2. Of the Fibrous Envelopes, - - 92 § 1. Aponeurotic Envelopes, - - ib. § 2. Of the Tendinous Sheaths, - - 93 §3. Of the Periosteum, - - - 94 Pathological Anatomy, - - - 95 § 4. Perichondrium, - - - 96 § 5. Of the Fibrous Envelopes of the brain, the Spinal Marrow, and some other organs, .... ib. § 6. Of the Fibro-serous, and the Fibro- mucous Membranes, - - 97 Second Division. Yellow elastic Fibrous System, - - 98 Pathological Anatomy, - - 99 Third Division. Fibro-cartilaginous System, - - ib. Pathological Anatomy, - - - 101 Bibliography of the Fibrous System, - - 102 INDEX. IX CHAPTER V. Cartilaginous Sistem, ------ 103 Section 1. General Observations, - — "-,- ib. Pathological Anatomy, - 105 Section 2. Articular Cartilages, ... - 106 Pathological Anatomy, - - - 108 Section 3. Perichondroidal Cartilages, - - - 109 Pathological Anatomy, - - - 110 Bibliography of the Cartilaginous system, - 111 CHAPTER VI. Of the Osseous System, ------ 112 Section 1. Of the Bones, - - - - ib. Article 1. General Observations, - - - ib. Article 2. Of the long, broad, short, and mixed bones, in particular, - 122 § 1. Of the long Bones, - - - ib. §2. Of the broad or flat Bones, - - 125 §3. Of the short Bones, - - - 127 §4. Of the mixed Bones, - - 128 Pathological Anatomy, - - - ib. Section 2. Of the Articulations of the Bones, - - 136 Pathological Anatomy, ... 140 Bibliography of the Osseous System. - - 142 CHAPTER Vn. Of the Nervous System, ------ 144 Section 1. General Observations, - ib. Section 2. Of the Nervous Centres, - - - 154 Article 1. Of the Cerebro-spinal Centre, - - ib. Pathological Anatomy, - 160 Article 2. Of the Nervous Ganglia, - - - 162 Section 3. Of the Nerves, ----- 167 Article 1. Of the Cerebro- Spinal nerves, - - ib. Pathological Anatomy, - - - 173 Article 2. Of the Ganglionic Nerves, - - 175 Pathological Anatomy, - 179 Bibliography of the Nervous System, - ib. CHAPTER VIII. Tegumentarx System, - .... 182 X INDEX. Section 1. General observations, - - - ib- Section 2. Of the Skin, - - - 188 Pathological Anatomy, - - - 198 Sectiono. Of the Mucous Membranes, - - - 205 Pathological Anatomy, ... 213 Section 4. Of the appendages of the Tegumentary System, 217 Article 1. Of the Hairs, .... ib. Pathological Anatomy, ... 221 Article 2. Of the Nails, - - - - 222 Pathological Anatomy, - - 225 AtiticleS. Of the Teeth, .... ib. Pathological Anatomy, - - - 230 Bibliography of the Tegumentary System, 231 CHAPTER IX. Glandular System, ...... 235 Pathological Anatomy, ... 240 Bibliography, .... 241 CHAPTER X. Muscular System, ...... 242 Section 1. General observations, - - - ib. Pathological Anatomy, - - - 253 Section 2. Of the Exterior Muscles, - - - 255 Section 3. Of the Interior Muscles, - - - 259 Bibliography of the Muscular System, - 263 APPENDIX, containing an account of the Accidental Tissues, - 264 Article 1. Of Tubercles, .... 266 Article 2. Of Schirrus, .... 268 Article 3. Of Encephaloid or Cerebriform Cancel', 269 Article 4. Of Melanosis, .... 270 Bibliography of Pathological Anatomy, - 271 INTRODUCTION. Life is the phenomenon which results from the actions of an assemblage of organs, which are more or less inti- mately connected together according to the ultimate func- tions which they are destined to perform. During a long time the study of the organs in relation to their form, their struc- ture and physical characters, and the study of the same parts in relation to their functions, were always combined, and were made the special object of the science of physiology. But in consequence of the progress of our knowledge of organi- zation, the separation of these two kinds of study has become essentially necessary. Anatomy is the science which treats of the conformation, the situation and structure of the or- gans, while physiology regards in a more especial manner, the funptions of the animal economy. Anatomy is divided into two branches; into special and general anatomy. The former has for its object the par- ticular study of each individual organ enjoying an action peculiar to itself; it describes the physical properties, the form and relative situation, and shows the mutual arrange- ment of the elementary tissues which contribute to its formation. The latter, of which this work is intended to present a summary, treats of the elementary tissues and or- ganic systems, considered in a general point of view, and abstractedly of the organs which they contribute to form. The term tissue is applied to every species of the ani- mal solids having peculiar and distinctive characters. The tissues are the constituent parts of our organs, or in other 2 INTRODUCTION. words, their elements. Each tissue, regarded as a whole, is called system, in whatever part of the body it is found. The human body is composed of solids and fluids, the latter of which, form by far the most considerable share. Before we enter upon the examination of the organic sys- tems, it is necessary to say something of those materials which perform a general and important character in the animal economy — a character, which, after having engag- ed for ages the exclusive attention and study of physicians, was lost sight of by the moderns, who uniformly sought in the solids the seat of every morbid derangement. Of the Fluids. It is impossible to determine with any degree of pre- cision, the relative quantity of the solids and fluids: some believe that the latter are to the solids as six to one; others that their relative proportion is as nine to one. The fluids are contained within the solids, which are more or less penetrated, according to the kind of organ that is examined. Their fluidity is owing more to the vi- tal influence than to the quantity of caloric which they contain. When drawn from the vessels of a living ani- mal, and removed from the heat to which they have been exposed, most of them coagulate. The animal fluids consist, first, of the fluids which are converted into blood; secondly, of the blood itself, which is the source and reservoir of all the other humours; and, thirdly, of the fluids which are derived from the blood. Of the Fluids which are converted into blood. The fluids which are converted into blood are the lymph and the chyle. The lymph is the milk-like fluid which results from the changes which the chymous pulp under- goes in the duodenum. Examined a short time after it has been absorbed by the chyliferous vessels of the intestines, it is slightly coagulable, of a saltish taste, and of a whitish INTRODUCTION. 3 appearance. In the glands of the mesentery, its charac- ters are sensibly modified; it becomes more coagulable, and presents a reddish tint, which, upon the arrival of the chyle in the thoracic duct, is changed to a beautiful red colour. Examined with the microscope, the chyle is found to con- sist of a great number of globules and corpuscles which are precisely analogous to those of the blood, with the excep- tion of their colour, which is much fainter. Lymph is a transparent, viscid and albuminous fluid, whose quantity is much smaller than is commonly sup- posed. It is contained in the lymphatic vessels, and is mixed with the chyle in the thoracic duct. Of the Blood. The blood of a healthy person, is a fluid of abeautful red colour, contained in the cavity of the heart, and blood- vessels, and varying in quantity from ten to twenty-five pounds. When flowing from its vessels in the living anij mal, it is an unctuous liquid of a peculiar odour and saline taste, of the temperature of 98° of Farenheit's thermome- ter, and of the specific gravity of 1050. The microscopic observations of Hewson, Beclard, Pre- vost and Dumas, tend to prove that the blood, while cir- culatingin its vessels, is nothing else than the serum, hold- ing in suspension small, regular, and insoluble corpuscles. These are uniformly composed of a central, colourless spheroid, and of a red, semi-transparent envelope. When the blood has ceased to be under the vital influ- ence, it gradually loses its heat, disengages a considerable quantity of carbonic acid gas, and coagulates. A short time after coagulation, the clot separates into two elements; the solid part is called the crassamentum, the fluid part, the serum of the blood. When the coagulum of the blood is carefully and repeatedly washed in a small stream of water, the colouring matter is gradually disengaged, and a glutinous and fibrous mass remains, which has been termed 4 INTRODUCTION. fibrin or coagulable lymph. This substance is of a grayish colour, of a firm consistence, and has all the properties of the muscular fibre. - The serum of the blood is of a greenish-yellow colour, and of the average specific gravity of 1030. It is alkaline, and when exposed to a temparature of 160°, it is converted into a white coherent mass, from which a fluid, termed the serosity, may be obtained by pressure. According to the analysis of Dr. Marcet, the serum conists of the following ingredients: — Water, .... 900.00 Albumen, .... . 86.80 Muriate of potash and soda, . 6.60 Muco extractive matter, . 4.00 Sub-carbonate of soda, 1.65 Sulphate of potash, 0.35 Earthy phosphates, . 0.60 1000.00 The colouring matter of the blood results from a mix- ture of the disengaged red matter and the serum. It is insoluble in water, and its chemical properties show that it is a peculiar animal principle united with a per-oxide of iron.* Besides these, the blood contains an unctuous substance, and a halitus which is seen to rise from the surface of blood recently drawn, upon the same principle that a sensi- ble evaporation takes place from the surface of other li- quids whose temperature had been considerably elevated. * According to the analyses of Berzelius, the colouring matter of the blood, after being incinerated, affords the following residue: — Oxide of iron, 50.0; sub-phosphate of iron, 7.5; phosphate of lime with a very small proportion of magnesia, 6.0; pure lime, 20.0; carbonic acid gas and loss, 16.5.— 100.0. (a)— S. D. G. (a) Thomas's System of Chemistry, Vol. IV. INTRODUCTION. ^ 5 During life the blood is constantly subject to the im- pulse of the heart, which, with the aid of other causes, pro- duces a continual circulation in its cavities, in the arteries and the veins. In the course which it traverses, the blood undergoes continual changes in its composition and nature; — changes which have for their ultimate object the nour- ishment of the organs. It is renewed and repaired by the chyle, which is carried to it by the thoracic duct; it re- ceives the refuse of all the absorbents, as well as the mole- cules which have ceased to form part of the body; it is vivified during the act of respiration, by which it loses a considerable quantity of serum and of carbon, absorbs oxi- gen, and changes from a dark red colour to a beautiful ver- milion: thus restored, it becomes the source of all the se- cretions and the vital principle of all the tissues with which it is incorporated. 3. Of the Fluids ivhich are derived from the blood. All the molecules which enter into the composition of our organs, or are thrown oflf, are derived from the blood, and are at first in a state of fluidity. These fluids may be divided into three classes: — 1. Into those which are immediately subservient to as- similation, to the growth, and reparation of our organs, or in other words, into those fluids which are especially nu- tritive. 2. Into those which are deposited into certain cavities, and in the intervals of the organs, as the fat, the serum, and synovia, as well as those which are exhaled on the surface of the body, as the cutaneous and pulmonary perspirations. 3. Into those which are the production of a glandular elaboration. They are, the mucus, the sebaceous matter, the lacrymal fluid, the salivary fluid, the bile, the pan- creatic fluid, the milk, the semen and urine. 6 INTRODUCTION. Of the Tissues and Organic Systems. It is difficult to determine the number of the elementary tissues of the body, because some of them are only modi- fications of each other, and also on account of the great dis- crepancy in the opinions of authors in^egard to this sub- ject. Some (Mascagni) regapd the solids as being com- posed entirely of vessels; others as formed of cellular tissue. Haller has admitted the existence of three kinds of primary tissues in the composition of our organs, viz., the cellular, the muscular, and the nervous. To this, M. Chaussier has added the albugineous fibre which enters mtp the composi- tion of the ligaments. M. Richerand also admits these four tissues, besides the horny substance which constitutes the basis of the epidermis, the nails, and the hair. Bichat divides all the tissues into twenty-one, three of which are the generators of the rest. These tissues are: — the cellular, nervous of animal life, nervous of organic life, arterial, venous, exhalent, absorbent, osseous, medullary, cartilagi- nous, fibrous, fibro-cartilaginous, muscular of animal life, muscular of organic life, mucous, serous, synovial, glandu- lar, dermoid, epidermoid and pilous. Beclard, including several of the preceding systems under the same denomi- nation, after Meckel, has described successively the cellu- lar tissue, the serous membranes, the tegumentary mem- branes, the vascular system, the glands, the ligamentous tissue, the cartilages, the osseous tissue, and the muscular and the nervous systems. As regards ourselves, in admit- ting the systems established by M. Meckel,* we have * Meckel recognises ten elementary tissues: — the mucous, serous, vas- cular, nervous, osseous, cartilaginous, fibrous, fib-o-cartilaginous, muscu- lar, and dermoid. M. Adelon divides the textures or systems into twelve classes: — the cellular, vascular, nervous, osseous, cartilaginous, fibrous, muscular, erec- tile, ?nucous, serous, corneous, and parenchimatous . Professor Mayer admits only seven systems.— the lamdkted tissue, the INTRODUCTION. 7 adopted an arrangement somewhat different from those that have been hitherto followed: we have endeavoured to classify the tissues in a manner expressive of their progres- sive complication. Thus we have placed after the cellular and vascular tissues, all those, which, being only modifi- cations of the first, present nothing in their organization but vessels, and appear to be destitute of nerves: — these are the serous, the fibrous, the cartilaginous, and osseous sys- tems. Then commences a second series at the head of which are the nervous system, and those which are com- posed of the tissues that are formed of a cellular net-work of vessels and nerves; viz., the tegumentary, the glandular and muscular tissues. Before we conclude, it is necessary to observe that this work, which we had intended to write together, is almost entirely the labour of M. Hollard, the health of M. Bayle having permitted him to take but a feeble part in it. ceUulo-fibrous tissue, the fibrous system, the cartilaginous tissue, the osseous tissue, the muscular fibre, and the nervous tissue. S. D. G. MANUAL OF GENERAL ANATOMY. CHAPTER 1. CELLULAR SYSTEM, SECTION 1. Cellular Tissue, properly so called. Synonyma: Cellular substance, body, membrane, org-an, mucous tissue, glutinous tissue, areolar tissue, reticular tissue, laminar tissue, fila- mentous tissue. Definition. The term cellular is applied to a soft spungy tissue, which is spread throughout the whole body, con- nects the various organs together, surrounds and insinuates itself between them, and enters into their substance in or- der to contribute to their structure. Division. This tissue forms a complete whole; but in consequence of the different relations, and of the more or less intimate connexions which subsist between it and the various organs of the body, it is necessary to distinguish it into common and special; and all that we have to observe respecting the manner in which the cellular tissue is ar- ranged in the animal economy, being applicable to these two divisions, we shall commence with the description of the first. 1. Common cellular tissue. The common cellular tis- sue regarded as a whole, presents the general configura- 3 10 CELLULAR TISSUE PROPERLY CALLED. tion of the body, forms a complete subcutaneous envelope, and has all the organs, with the exception of the teguments, embedded in its mass. Its quantity is not every where the same: proceeding from the exterior to the interior parts of the bod} T , we find that it abounds under the skin, particu- larly in the face, in the anterior and lateral parts of the neck, the parietes of the thorax and abdomen, the scrotum, in the vicinity of the large joints, and in those places where extensive flexion is performed, especially in the axillae and groins; between the lamina? of the mediastinum, around the large vessels, in the inferior part of the cavity of the abdomen, particularly around the kidneys, between the folds of the peritoneum, but still more around the pelvic viscera; — an arrangement favourable to the changes of volume accompanying the exercise of their functions. This tissue, on the other hand, is thin on the mesian line of the body (except in the neck,) under the teguments of the head, in the cavity of the cranium, and in the vertebral ca- nal, especially between the dura mater and bony case. The common cellular tissue which is spread over the ex- terior parts of the body, communicates with that of the in- terior by all the interstices which are left between the dif- ferent organs, but in a still more remarkable manner by the orifices and inter-organic spaces which give passage to vessels and nerves. This kind of communication takes place in the holes of the cranium and vertebral column, and in the cavity of the thorax, where the cellular tissue of the neck and arms enters in accompanying the vascular trunks and nerves which enter and pass out at the superior part of that cavity. From the thorax it passes into the cavity of the abdomen between the pillars of the diaphragm along with the oesophagus, the aorta and vena cava; and at the crural arch and inguinal ring, it communicates with the cellular tissue of the inferior extremities. 2. Special cellular tissue. Considered in its more di- rect relations with the organs, we observe, that the cellu- CELLULAR TISSUE PROPERLY CALLED. 11 Jar tissue surrounds and envelops them with a particular covering, which forms, according to the happy expression of Bordeu, an atmosphere of insulation, that enters every where into their intimate structure. 1. The cellular tissue which covers our organs is form- ed by a condensation of the common cellular tissue, of which it is a continuation. Its thickness varies in the dif- ferent regions of the body; it is more considerable around the parts which perform extensive motions, and those which are not insulated by a membranous envelope, as the thy- roid gland, the kidneys, &c. The skin, the mucous and serous membranes, the vessels and excretory ducts are lin- ed only at their adherent surfaces, by a layer of cellular tissue. a. Under the skin this layer is not every where equally dense and compact: it is most so in the palm of the hand, the sole of the foot, around the annular ligaments, and on the mesian line of the body; on the other hand, its laxity is remarkable in the eye-lids and scrotum. b. The submucous layer is generally more dense than the preceding: so that it seldom contains any collections of serum: this character is indispensably necessary, in order that the muscular fibres which are inserted into it may have a point of attachment. c. The serous membranes, intended, mostly, to facili- tate more or less extensive gliding movements, are fur- nished, at their adherent surface, with a loose cellualar tis- sue, which is particularly conspicuous in the abdomen: notwithstanding, some parts of the pericardium, the great- est part of the synovial and arachnoid membranes, adhere intimately to their respective organs. d. It forms layers that envelop the blood vessels, lympha- tics and excretory ducts: those around the arteries are ex- tremely compact, condensed, and resisting, in order to pre- serve their cylindrical form when they are insulated; those of the veins and lymphatics are less thick and compact; 12 CELLULAR TISSUE PROPERLY CALLED. while those of the excretory ducts are thicker than those of the veins and thinner than those of the arteries. The organs, which are composed of a substratum of seve- ral membranes, present a more or less compact cellular tis- sue between them, which belongs in part to the submu- cous and subserous layers in the intestinal canal and in a portion of the bladder, and which, considered in relation to their tunics, enjoys the character of the exterior cellu- lar tissue, notwithstanding it must be regarded as interior, when we take into consideration the organs with which it is connected. It forms in fact a transition between the subdivision of which we have just spoken and the follow- ing. 2. The cellular tissue, after having covered the organs, enters every where into their structure, and envelops the most minute parts of their substance. Thus, each fasciculus, every muscular fibre and fibrilla, the glands and every glan- dular particle, are surrounded by a pouch or cellular sheath. This pouch is more delicate in proportion as the organic particle which it surrounds is more minute. A cellular tis- sue, more lax than that which forms these pouches, separates them from each other: in short, the interior cellular tissue is destined to the same uses, in relation to its parts, that the com- mon cellular tissue of which we have just spoken, performs for the organs. We perceive but little cellular tissue in the brain and spinal marrow, in the bones and ligaments; and it can be seen in the cartilages only after a long and tedi- ous maceration. Structure. What is the interior conformation of the cellular tissue? If we examine a portion which has neither been stretched nor distended by fluids, it will present, ei- ther the aspect of a homogeneous, semi-transparent sub- stance, or an appearance of a lamellated and filamentous texture; the first form appertains particularly to the special cellular tissue, the second to the common tissue: moreover, if we separate two bodies that have been united by cellular CELLULAR TISSUE PROPERLY CALLED. 13 tissue, we shall observe that the latter is composed: 1st, Of transparent lamina, especially in those regions where it is of a loose texture, as in the eye-lids and scrotum; and 2d, Of filaments, which are either single, or interlaced with these laminae. Both are soft and whitish, and may be greatly distended before they break. If air or water be Imtrodrrceo^into this tissue, these fluids will permeate it with the greatest facility and occupy the irregular cells, which are formed by the interlacement of the laminse and filaments, to which we have just alluded. The existence of these cells can be rendered evident by freezing an infiltrated limb; numerous little icicles will be formed, and show by their form that of the cells which they occupied. From these facts Haller, Bichat, Beclard and M. de Blainville, of the present day, as well as most of the English and Ita- lian anatomists, have concluded that the cellular tissue has a lamellated and filamentous texture from which resulted the existence of irregular permanent cells, varying in figure, and communicating with each other. Bordeu, notwith- standing, has asserted that the tissue, now under consider- ation, was merely a homogeneous substance, destitute of form, and of a viscous, gelatinous nature. Adopting this method of observing, Wolff, and more recently Rudolphi, Heusinger, J. F. Meckel, and ethers, have maintained that the laminse, filaments and cells of the cellular tissue do not naturally exist, but that they are produced by distention, and that similar phenomena may be produced by distend- ing a mass of mucus or glue: consequently they have de- scribed the cellular tissue under the name of the mucous tissue.* In answer to these assertions we may observe: first, that the texture of the cellular tissue is evident in a number of places, without previous distention;! secondly. * May we call this tissue an amorphous and perfectly homogeneous substance, as these authors conceive it to be? f Meckel appears to acknov/ledge this fact, by saying 1 , that the opinion opposed to his is at least too common. 14 CELLULAR TISSUE PROPERLY CALLED. that its permeability is too remarkable to belong to a ho- mogeneous and viscous substance,* and that, performing the office of a spongy and cellular tissue, it ought, thus far, to be regarded as such. Our ideas of the nature of cellular tissue are vague and hypothetical. According to Meckel, it consists of a coagulable fluid in a state of coagulation. Ruisch and Mascagni assert, that it is composed of vessels; Fontana, of tortuous cylinders. Be this as it may be, it is certain that it is supplied with a great number of capillary vessels, which it furnishes with coats, and which carry red blood only when they are in a state of inflammation Differences according to age. The cellular tissue, the basis of all the others, is represented in the first periods of gestation, by a viscous substance, in the midst of which the organs are developed — a substance, which diminishes, ac- quires consistence, and after having passed from a state of mucus and gelatine, at length assumes the texture which we have already described. Bichat supposed that the fila- ments and layers existed in the first period of the embryon, and could not be perceived on account of their tenuity and the quantity of the fluid which filled their interstices. As the organs are developed, the mass of the common cellular tissue gradually diminishes; notwithstanding, it continues to be predominant for many years after birth. The same thing takes place during a great part of the life of the fe- male; hence, that rotundity of form common to her and the infant. In the latter, the cellular tissue is more delicate, its serum more abundant, and its vital energy more con- spicuous than at any subsequent period of life. In the adult, it becomes more firm and condensed, is less humid, forms layers of a more compact texture and renders the subcutaneous organs more prominent. In old age, it is dry, * In consequence of wounds of the lungs, air sometimes penetrates into the cellular tissue with a promptitude and facility that could not be explained without admitting the pre-existence of cells. CELLULAR TISSUE PROPERLY CALLED. 15 less elastic, and somewhat withered; — a circumstance to which must be attributed in part, the wrinkles under the skin of old people. Physical and chemical properties. The cellular tissue, almost colourless when distended, presents a grayish white appearance whenever it forms a thin layer; its cohesion, which is in direct ratio with its density, forms a medium between that of mucilage and the fibrous tissues. It is eminently elastic. Exposed to putrefaction, the cellular tissue yields to it less readily than many other animal substances; it resists for a long time the action of the gastric juices, and of ebul- lition; and months are scarcely sufficient for its maceration. It is composed principally of gelatine, with a small quan- tity of fibrin and earthy salts. Vital properties. In the healthy state, the sensibility of this tissue is very obscure; it evidently possesses some degree of contractility of texture, which is more conspicu- ous in youth than old age. Functions. The common cellular tissue serves to con- nect the organs together, and by its pliancy and elasticity, to facilitate their motions. It serves, more immediately, to form around them a kind of atmosphere, which contri- butes to protect them from the diseases of the neighbouring parts; and, in furnishing an envelope for their most minute corpuscles, to determine their extent and configuration. This tissue is the seat of a serous exhalation,* principally composed of albumen, which moistens it continually, and serves to facilitate the motions of the contiguous parts. It is small in quantity, and when the tissue which it lubri- cates is laid bare in a living animal, it appears under the form of vapour: it is continually furnished by the exhalents and taken up by the absorbents. We may observe, that its * Many anatomists suppose that this secretion is produced by an ela- borating - process of the cellular tissue. 16 CELLULAR TISSUE TKOPERLY CALLED. quantity is in an inverse ratio to that of the fat in the dif- ferent regions.* Pathological Jlnatomy. The cellular tissue is the basis of many adventitious pro- ductions, as polypi, fungi, cicatrices, &c. &c. which prove its great plastic energy. When a re-union can not he immediately effected, after a solution of continuity, the denuded surface puts on an in- flamed appearance, and soon after becomes covered with red granules, improperly called fleshy granulations, since they result from a development of the inflamed cellular tissue, and not, as was asserted by Galen, from a repro- duction of flesh. As these granulations grow, they secrete purulent matter, become uneven at their surface, and con- tract; while this is taking place, the secreted matter be- comes thicker, and is at length organized under the form of a thin pellicle, which is continued with the neighbouring epidermis: under this, the depressed granulations are con- verted into a wrinkled tissue, which is analogous to the chorion of the skin, and which gradually loses its reddish tint, and becomes whiter than the original skin. This forms what is called a cicatrix. These phenomena take place from the circumference towards the centre of the wound, whose edges approximate, from this last point, in consequence of the contractions of the granulations. From this it results that the cicatrices occupy less space than the original wound. After the immediate re-union of a solu- tion of continuity, there are neither granulations nor pus; the cicatrix being formed by an effusion of adhesive matter upon the surface of the wound, which becomes at first more * The fatty fluid placed hitherto upon the same line as the serosity in the history of the cellular tissue, appears to be deposited in a particular tissue which has been described separately, as a modification of the cel- lular tissue: as this distinction appears to be well founded, we shall de- scribe the adipose or fatty tissue under a distinct section. CELLULAR TISSUE PROPERLY CALLED. 17 dense than the cellular tissue, but is finally confounded with it. The cellular tissue is frequently distended by collections of the serum, which lubricates it. When this affection is local, it is termed anasarca, and oedema, when it extends throughout the whole system. It is most frequently con- nected with chronic diseases of one or more of the princi- pal viscera, or with an obstruction of the circulation: the most dependent parts of the body are the ordinary seat of oedema. When serum is extravasated into the cells of the cellular tissue, it leaves the part where it is found as soon as their position is rendered less dependent; another proof of the great permeability of this tissue and of the pre-exist- ence of its cells. Air sometimes penetrates into this tissue, in consequence of wounds of the thorax, &c; gas also is disengaged in certain cases; this kind of infiltration is called emphysema. The cellular tissue is frequently the seat of phlegmonous inflammation, which may be dispersed by resolution: when acute, it often terminates in suppuration, that is, by the secretion of a white, inodorous, cream-like fluid, (pus) which, being at first disseminated through the cells in which it is formed, collects into an abscess, .and has a tendency to travel towards the surface; which is readily effected when the inflammation has some degree of inten- sity and the situation of the purulent abscess is not obstruct- ed: under these circumstances portions of cellular tissue are often discharged with the pus. If the disease is somewhat slow in its progress, the parietes of the abscess become lined by a membrane, resulting from the condensation of the cellular tissue, and which has some analogy to the mucous membranes. When the pus is evacuated, these parietes approximate and the cavity of the abscess is obliterated; or if the matter continues to discharge, the course which it takes to arrive at the external surface, is also lined by a mucous membrane, and is thus converted into a fistula. In some instances, the abscesses are intersected by bands and 18 CELLULAR TISSUE PROPERLY CALLED. partitions, which are nothing more than the remains of the cellular tissue which occupied their cavity. The gangren- ous eschars, which often result from acute phlegmonous in- flammation, are soft and grayish, and are called ventriculi furuncu/orum. Those which are formed in some phleg- monous tumours, as furunculus and anthrax, are attributed to a kind of strangulation of the inflamed cellular tissue. Inflammation, after it has passed into the chronic state, often deposits into the cells of the cellular tissue, a kind of concrete matter, which gives rise to the alteration called white induration: this constitutes the granulations which are often exhibited in the subserous and submucous cellular layers. The elephantiasis of Barbadoes consists in a morbid derangement of this kind. The induration of newly formed cellular tissue, which M. Chaussier has called scleremas, is a disease almost ex- clusively confined to infants, and is characterized by a con- siderable degree of firmness and consistency of this tissue, especially of the subcutaneous: incisions made into it pro- duce a discharge of a yellowish fluid, which, according to Meckel, consists of a mixture of fat and serum. By Andry this disease is attributed to a suppression of the cutaneous perspiration; by others, to an effect of syphilitic virus. According to the researches of M. Breschet, it is attended with an opening of the foramen of Botal, and consequently by a very evident imperfection in the function of respira- tion. When foreign bodies are introduced into the cellular system, they cause inflammation in the contiguous parts, and are most frequently discharged by suppuration; though sometimes they penetrate to a considerable distance: intro- duced into the alimentary canal, they often pierce its coats, and are conveyed through the different regions of the body, without occasioning any serious mischief.* The cellular tis- * A case of this kind occurred in a woman who suffered from mania, in consequence of swallowing needles. She died several years after at CELLULAR TISSUE TROPERLY CALLED. 19 sue is sometimes condensed around them and forms a mem- branous covering or cyst (v. Serous System.) The blood, the product of the secretions and the excrements are some- times extravasated into this tissue and act as foreign bodies: the blood, at first diffused through the cells of the cellular tissue, constitutes what is called ecchymosis, and is often brought to a focus before it can be absorbed: hence, it is converted into a coagulum, which, being enveloped in a serous cyst, is soon after more or less readily absorbed. When the pecrementitial secretions are extravasated, they readily enter the circulation; and their presence in the cel- lular tissue often brings on the most fatal inflammations. The cellular tissue is sometimes the seat of organized beings, such as hydatids, &c; the filaria dracunculus of Bremser, and the furia infernalis enter it by piercing the skin. Bibliography. Th. de Borden. Recherches sur le tissue muqueux ou or- gane cellulaire, etc. Paris, 1767 — 1791, et dans les (Euvres completes publiees par le chevalier Richerand. Paris, 1818. Haller. Elem. phys. corp. hum., 1. 1, p. 9. Lausanne, 17S7. X. Bichat. Anatomie generale, tome I, page 100. Ed. de Beclard. Paris, 1821. Br. Hay ward's Trans, of the same, vol. I, page 87. Bos- ton, 1822. P. Ji. Beclard. Elemens d'anatomie generale, 1 vol. in 8. Paris, 1S23, p. 133. J. Fr. Meckel. Handbuch der menschlichen anatomie, c'est-a-dire, Manual d'anatomie humaine, traduit en frangais sous le titre de Manuel d'anatomie generale, de- scriptive et pathologique; par MM. Jourdan et Breschet. Paris, 1825, tome I, page 103. the Hospital of St. Louis, and upon post mortem examination, several hundred of these small instruments were found in the cellular tissue of the different parts of the body. 20 ADIPOSE TISSUE. SECTION 2. Adipose Tissue. Synononyma: Cellulo-fatty tissue, fatty membrane, web (toile, - ) adipose tunic. The existence of the vesicular tissue into which the fat is deposited, has not been acknowledged by all anatomists. Malpighi,Morgagni, and particularly Mr. W. Hunter, and more recently, Proschaska, Mascagni, MM. Chaussier, and Beclard, have described this tissue as distinct from the preceding; but Bichat, adopting the ideas of Haller, as- serted that the fat was exhaled and deposited like the serum into the areolae of the cellular tissue. In our day, J. F. Meckel has described the fatty fluid as contained in small rounded, irregular vesicles, formed evidently by a kind of gluten, which, according to him, constitutes the cellular tissue. The facts upon which the distinction of this and the adipose tissue rest, re-established lately again by Be- clard, have appeared sufficiently conclusive to justify us in describing this tissue under a distinct section., Definition. The adipose tissue consists of small, micro- scopic vesicles joined together in more or less considera- ble masses and filled with fat. Situation. The adipose tissue abounds exteriorly un- der the skin of the face, the neck, the anterior parts of the thorax, the abdomen, the nates, the palms of the hand and the soles of the feet, and in the great interstices between the muscles. It is to the accumulation of a great quantity of this tissue that is to be attributed the enormous devel- opment of the nates of the Hottentot women, of the tail of the Barbary sheep, and the prominences on the backs of some animals, that, for instance, of the camel. Interiorly, the adipose tissue occurs chiefly around the great vessels, on the surface of the heart, around the kidneys, between ADIPOSE TISSUE. 21 thefolds of the mesentery and the omentum. It exists more- over under the denomination of the medullary substance, in the bones where it occupies the cells of the spongy and reticular substance, the microscopic interstices of the compact substance and the medullary canal of the long bones: here the adipose vesicles are deposited into the cells of a cellulo-vascu- lar membrane, of which we shall speak more particularly in the history of the osseous system. The interior of the cra- nium, the globe of the eye, the eye-lids, the penis and the scrotum, the submucous cellular tissue, the lungs, &c. are in general destitute of fat.* In persons of ordinary plump- ness, the fat is generally wanting in those organs where its presence would interfere with the exercise of their functions. Differences of situation and quantity, according to age and sex. — It is not until about the fifth month after conception, that the foetus presents some insulated adipose vesicles, and then only under the skin. After birth, it becomes more abundant, is seen in the more deep seated parts, and finally in the visceral cavities. Its quantity is much greater in adult age, than in the subsequent periods of life, and in woman than in man. In old age, it occurs almost exclusively around the viscera of the thorax and the abdomen. Form. The adipose tissue is sometimes seen under the form of considerable laminae, as under the skin; sometimes, under that of pelatons, as in the orbits; and at others, un- der that of bands, as in the epiploons, &c. Structure. In examining the texture of a portion of adi- * "If the cellular membrane," says Dr. W. Hunter, "had been adi- pose in the eye-lids, fat people must have been blind; if in the substance of the lungs, they must have been suffocated. Had it been adipose within the skull, fat people would have been as liable to apoplexies as to ruptures; and if it had not been reticular in the penis, fat men would have been much incommoded." Med. Obs. and Inq. v. ii. p. 31, Lon- don, 1762.— S. D. G. 22 ADIPOSE TISSUE. pose tissue, it will appear at first sight to be composed of small, oblong masses which result from an assemblage of military granules, formed by the agglomeration of a multi- tude of small round and transparent vesicles, which are somewhat compressed and visible only by the aid of the microscope. The coats of these vesicles, which probably result from a modification of the cellular tissue, are indis- tinct, yet their existence can noibe doubted for the follow- ing reasons; 1st, When a portion of adipose tissue is ex- posed to a temperature capable of melting the fat which it contains, it does not run out, which would take place were the fat not confined within the cells of the cellular tissue. 2d, Although fluid during life it never gravitates, however abundant it may be, toward the more dependant organs, and 3d, it is not like the cellular tissue, spread throughout the whole body, a fact, which would at least indicate some difference of organization. The adipose vesicles are con- nected together by very fine cellular tissue, and are sup- plied with blood vessels that may be readily injected.- These ramify at first between the small oblong masses, forming there a kind of net-work which sends to each grain a pedicle composed of an artery and a vein, whose ramifi- cations are distributed, like so many smaller pedicles, to each vesicle in which they appear to terminate. There is but little known with respect to the lymphatic vessels of the adi- pose tissue, and we are yet entirely ignorant whether it re- ceives any nerves. Physical and chemical properties. The extreme tenui- ty of the adipose vesicles is the reason that we know no- thing of its physical and chemical properties, except those which result from the presence of the fat contained in the adipose tissue. Vital properties. In the healthy state, the adipose tis- sue, is entirely destitute of sensibilit} 1 ", and can not be dis- tinguished, even when in a state of inflammation, from that ADIPOSE TISSUE. 23 of the surrounding cellular tissue. Its contractility is very- obscure, but it probably participates in that of the preced- ing tissue. Functions. The adipose vesicles serve as a reservoir for the fat, which is fluid during life, and varies in colour, consistence and odour in the different kinds of animals. Human fat is an inodorous substance, of a yellowish co- lour, ofa faint sweetish taste, specifically lighter than wa- ter, and fusible at a temperature of 15° cent.* It is insolu- ble in water, and less soluble in cold than boiling alcohol. At an elevated temperature it is decomposed, and affords hydrogen, oxigen and carbon in various degrees of combi- nation. Its combination with the oxigen of the air gives rise to the sebacic acid. By distillation, it yields Celtic acid and a considerable quantity of defiant gas; and by treating it with the alkalies we obtain the margaritic and oleic acids and the sweet principle, (Chevreul.) These last products do not exist naturally, but are the results of new combina- tions. The experiments of M. Chevreul have shown, that the fat contains two proximate principles, to which he has given the names of elaine and stearine; the former, solu- ble in alcohol, fluid at 7° cent, the latter less soluble in al- cohol and fluid at a little below 3S° cent. The degree of fusibility of every kind of fat is in proportion to the rela- tive quantity in which these two principles are combined. Various are the hypotheses that have been advanced re- specting the manner in which the fat is secreted, and the organic agents upon which it depends. Malpighi believed for a short time, that the vessels of the adipose tissue were accompanied by a small secretory apparatus; but this great anatomist soon abandoned an idea which was utterly desti- tute of foundation, and which has since given way to others. Riegel asserted that the glands, and particularly the capsu- Ise renales, were the secretory organs of the fat. Haller supposed that it circulated with the blood; that it floated * The harder varieties of fat fuse at about 120° Fah.— S. D. G, 24 ADIPOSE TISSUE. upon its surface on account of its specific levity, and escap- ed through the coats of the vessels; but the most common- ly received opinion of the present day, is, that the fat is ex- haled from the parietes of the adipose vesicles. This ex- halation is sometimes remarkably abundant, especially af- ter protracted abstinence; it is also favoured by sedentary habits, a farinaceous diet and castration. It is here, as every where else, continually counterbalanced by absorp- tion, which frequently exceeds it, particularly in some of the chronic diseases of the principal viscera, in cases of pro- tracted or profuse suppuration, diarrhoea, and some other af- fections. The fat appears to be useful in the animal economy, prin- cipally by protecting certain parts from the inconveniencies of habitual pressure to which some of them are exposed; such is its use in the soles of the feet, the nates and some other parts. As a bad conductor of caloric, it contributes in some degree to the preservation of that of the body; but its most important office appears to be nutrition, and it may be re- garded, if we may be allowed the expression, as aliment in reserve. Examples of this kind are furnished us in hy- bernating animals. The fat in the bones appears to answer no other purpose than that of the other organs. It was falsely asserted by Haller that it renders the bones less brittle, that it was subservient to their consolidation after fractures, to their nutrition, &c. &c Pathological Jlnatomy. Obesity, or polysarcia, as it is technically called, results from the excessive development of the adipose tissue, and may be regarded as a morbid derangement which impedes the functions of the other organs. When this extraordina- ry growth is local it is termed lipoma. It is often sur- rounded by a kind of cyst, and generally presents one or more peduncles. Tumours of this description have been seen that have weighed from thirty to forty pounds. They ADIPOSE TISSUE. 2o are all of an irregular spheroidal figure, and are most com- monly seated beneath the skin; sometimes, however, they are found in the cavities of the thorax and the abdomen, particularly in the omentum: when they pass out through the inguinal ring, &c. they are called fatty hernias. In- flammation of lipomatous tumours and of the cellular tis- sue in general, frequently terminates in gangrene: this morbid state, also, may bringon schirrous and carcinomatous affections. The adipose tissue is often developed in the ovaries, in the submucous cellular tissue, and in other parts where it is seldom found in the healthy state. The muscles and some other organs are subject to fatty produc- tions, which according to Beclard belong only to the for- mer. Of these we shall speak in the history of those or- gans in which they are developed. — Traumatic inflamma- tion of the adipose tissue produces an evacuation of the vesi- cles and an effusion of the fat upon the surface of the wound, which is soon covered with cellulo-vascular granu- lations, and is cicatrized in the same manner as we point- ed out in the preceding section. In the infiltrations of the cellular tissue, the serum is ex- travasated between the granules and the adipose vesicles, so as to separate them from each other, and to render them very distinct. Bibliography. Malpighi. De omento, pinguedine, etc., m Epist. anat. London, 1686, p. 33. W. Hunter. Remarks on the cellular membrane, etc., in Medic. Obs. and Inq. vol. 2. p. 26. London, 1762. Biclard. Op. Cit. p. 156. ChevrenZ, dans les Annales de Chimie, tome xciv, et les Annales de chimie et de physique, tomes n — vn. J. e/2. Sayssi. Secherces experimentales anatomiques, chi- miques, etc., sur la physiologie des animaux mammife- reshibernas. Paris, 1808. 26 VASCULAR SYSTEM. CHAPTER II. - VASCULAR SYSTEM. SECTION 1. General Observations. Definition. — The vascular system is composed of an as- semblage of membranous tubes or vessels, which are uni- ted together so as to present an arborescent arrangement, and are traversed by the fluids which are subservient to nutri- tion and secretion. Division. — This system presents three orders of vessels: two convey the blood, and are called arteries and veins; the third comprehends the lymphatic vessels, which carry to them the lymph and chyle, white fluids, the first of which is derived from all the organs, and the second, the product of digestion, is absorbed on the internal surface of the intestines. Considered in their relations with the heart and the nature of the blood which traverses them, the arteries and veins have been distinguished into those of the pulmonary and those of the general system; but Bichat, struck with the analogy of their functions rather than their anatomical cha- racters, united the vessels which correspond to the same lateral halves of the heart, and obtained the most beautiful results from this division of the sanguineous system into the circulation of red and that of black blood. General conformation. — The three divisions of the vas- cular system form an uninterrupted whole, which is called VASCULAR SYSTEM. 27 the circulatory apparatus, because its arrangement is such, that the fluids which traverse it, return to the cen- tre where they began their circuit: let us give a general idea of it. An artery, called the aorta, arises from the left ventri- cle of the heart,and carries, by its numerous ramifications, the red arterial blood to every part of the body; hence, arise a multitude of small veins which are continuous with the minute extremities of the arteries, and which, uniting successively, terminate, after having received the lympha- tic vessels, by the two venae cavse and coronary vein, which pour the dark venous blood into the right auricle of the heart. From the right ventricle of the heart originates the pulmonary artery, whose divisions, multiplied ad infini- tum, distribute this black blood through the lungs, where, by the act of inspiration, it is converted into a beautiful red colour, as it passes from the minute arterial extremities into those of the venous: these last form, by their successive junctions, small ramifications, then branches, and termi- nates by the four pulmonary veins, in the left auricle of the heart. We have already said, that the heart is the point of uni- on of the great vascular trunks: in proportion as these re- cede from their origin, they divide into branches, these branches into smaller ones, and these progressively into more and more minute ramifications. All the vessels are of a cylindrical form, and preserve a uniform diameter from the place of their origin to that in which they ramify. This, for instance, is the case with the spermatic artery, which traverses a long course without changing its dimensions. If any of the smaller branches be less than the branch from which they arise, their united caliber will be greater than that of the original branch; so that the vascular system re- ally increases as it becomes more remote from the heart: it is in this way that anatomists, by reflecting on the divi- sions of this system, have compared it to a cone, the apex 28 VASCULAR SYSTEM. of which is formed by the heart, and the base, by the ex- tremities of the smaller vessels. The s} r mmetry of the vascular system is by no means so • uniform as that of the nervous system. The heart and great trunks are not placed exactly on the median line, and the vessels that correspond are not all given off in the same manner; thus, the arteria innominata gives origin on the right side, to the subclavian and primitive carotid, which, on the left side, arise separately from the aorta; in general, however, the origin of the trunks is pretty uni- form; while that of the branches is so variable that hardly any two subjects present the same arrangement. Differences of vascularity in the different organs. — The organs do not all possess the same degree of vasculari- ty; those which are the most plentifully supplied with blood-vessels are: first, the lungs, the tegumentary system, the pia mater and choroid membrane, the glands, the folli- cles, the cortical substance of the brain, the nervous gan- glia, the muscles and glandiform bodies; secondly, those which are most abundantly supplied with lymphatic ves- sels are: the lymphatic ganglia, the serous membranes, the cellular tissue and glandiform bodies. — No vessels have hitherto been demonstrated in the cartilages and appenda- ges of the skin. The azygos organs, which are divided into two lateral halves by the mesian line, receive the same num- ber of vessels from either side; but there are but few organs^ with the exception of the eye, the testicles and kidneys, that receive many vessels of each kind. Examined in those parts in which they are distributed and pass out, the vessels present a great number of divisions which form fre- quent anastomoses wjth each other. The most minute vessels, known by the name of capil- laries, are spread throughout every part of the body, as may be demonstrated by microscopic inspection and injec- tions. The smaller, less delicate branches, are found more particularly on the superficjes of the body; while the VASCULAR SYSTEM. 29 branches are situated more deeply, and are embedded in a quantity of cellular tissue, which fills up the great interstices of the organs, particularly in those regions where flexion is performed. The vascular trunks are found exclusively in the cavities of the thorax and abdomen. Mode of Division. — The mode of division of the vessels varies in the different parts of the body. Sometimes it consists in a bifurcation, and forms branches that correspond with each other in length and diameter; it is in this way that the aorta terminates in the abdomen; most frequently, however, a branch is separated from a trunk, which con- tinues its course; in this case we observe no uniform pro- portion between the volume of the first and that of the second. The origin of the vessels is commonly near their place of destination, and it is seldom that we see them run *%iy considerable distance without furnishing divisions: the spermatic artery is of the small number of those which form exceptions to this rule. When they divide, the vessels form various angles, but, most generally, they are acute, especially in the extremi- ties. The divisions of the great trunks, however, present many examples of right angles, while the superior inter- costals, and recurrent arteries of the extremities are given off at a very obtuse angle. Mode of communication. — The different kinds of ves- isere communicate with each other, not only because they result from the ramifications of the. same trunks, but also from the connexions called anastomoses, which we shall describe in a subsequent part of this work. Two vessels sometimes meet and unite to form an arch, from the convexity of which small branches are given off, especially in the neighbourhood of the joints, the intestinal canal, the hand, the foot, &c; at other times, the commu- nication is effected by means of, an intermediate branch, as in the two anterior cerebral arteries, the vena cava and umbilical vein, &c. Two equal trunks sometimes unite at an > 30 VASCULAR SYSTEM. acute angle, and form but one, which takes a middle direc- tion between that of the original trunks. It is thus that the two vertebral arteries unite and form the basilar. All the different kinds of anastomoses come under the head of one of the varieties which we have just noticed. They are more frequent in proportion as the vessels are smaller, more nu- merous and superficial. The anastomoses of the lymphatics are more numerous than those of the veins, and those of the veins than the arteries. Their principal object is, to facilitate the circulation of the fluids, and to maintain it by means of collateral passages, when one of the principal vessels has been obliterated: it is in this manner that the cir- culation is performed, although some of the larger branches shall have shrunk and even become obliterated. Surfaces. — The vessels adhere by their external surfac to the surrounding cellular tissue, which is condense around them so as to form a sheath. Their internal sur- face is smooth, even, and slippery, continually moistened by a serous exhalation, and marked by semicircular projec- tions, which correspond to the angles that are formed by the branches in separating from their trunks. Structure. — The parietes of the vessels are formed of several cylindrical membranes, whose structure and other characters differ in the different kinds of vessels; we shall describe them in treating of the history of each order of vessels in particular. Their coats are thicker in propor- tion as their caliber is smaller; they receive minute branches of blood vessels and lymphatics (vasa vasorum,) and their nerves, which are derived from the cerebro-spinal centre and the great sympathetic, form a kind of reticulum around their external surface. Physical and vital properties. The physical and vital properties of the vessels, as well as their functions, differ much, in the different kinds of vessels, as we shall remark in the following sections. VASCULAR SYSTEM. 31 Mode of development and differences according to age. — The mode of development of the vascular system has not hitherto been examined, either in man, or in the mammi- ferse, and all the knowledge that we possess on this subject has been derived from examining the eggs of birds. The vitelline membrane, which appears to correspond to the earachus of mammiferous animals, exhibits at first, small, isolated fissures, which are filled with a thin, transparent fluid, and which, as they increase in number, assume the form of a small tree whose trunk appears in a short time after, and forms the omphalo-mesenteric vein, which at this period contains red blood. It passes from below upwards, Aon the anterior surface of the embryon, dilates and forms mhe heart; the arteries are formed soon after, and finally lhe veins. These circumstances would induce us to believe "at the embryon of the mammiferous animals is develop- ed in the following order: that the umbilical vein is formed first, and that the development of the arteries of the belly precedes that of their corresponding veins; in short, that the order of appearance of the vessels is in proportion to the increasing quantity of the fluids which traverse them. The organs are at first mere hollow canals, embedded in the surrounding substance, which is gradually condensed around them so as to form distinct parietes; so that they acquire their proper texture only by slow degrees. In old age, the coats of the vessels, especially those of the arteries, become very condensed and brittle. As to the number of vessels, it is during foetal life that it is the most considera- ble; and it is at this period that we find different branches which are obliterated after birth; such are the umbilical vessels, the ductus venosus and ductus arteriosus. Pathological Jinatomy. The anomalies of origin, situation and form, are frequent in the vascular system; we shall have occasion to point out some of them in speaking of the different kinds of vessels, o2 Of THE ARTERIES. We observe in the tissues, which have their analogies in the animal economy, as well as in cicatrices, adhesions and pseudo-membranes, vessels which are at first develop- ed separately, like those of the urachus, and which com- municate afterwards with those of the contiguous parts. The pathological anatomj- of the vessels varies so much in the different kinds of vessels, that it can not claim our at- tention on the present occasion: we shall revert to it in the following sections. sectiox 2. Of the Arteries. Definition. — The arteries are the vessels which carry the blood from the heart to every part of the body. Division. — There are two arterial trees, the pulmonary and the general; the first carries black, the second red blood. General arrangement. — The arterial system consists of two principal trunks which arise from each ventricle of the heart. The one, called the pulmonary artery, arises from the right ventricle, and, as it ascends, it divides into two branches, one on either side of the aorta, the right to b*e ramified on the right lobes, and the left on the left lobes of the lungs; the other, called the aorta, arises from the left ventri- cle, passes upwards towards the superior part of the thorax, furnishes large branches, which are distributed on the neck, head, and superior extremities; after which, it forms a great curve, descends along the anterior part of the left side of the bodies of the vertebrae, furnishes branches to the vis- cera of the abdomen, and divides, between the fourth and fifth lumbar vertebras into two secondary branches, which are distributed, after having sent branches to the pelvic viscera, on the inferior extremities. The arteries, after a certain number of divisions, (twen- OF THE ARTERIES. 33 ty-one according to Haller and Bichat,) terminate in the capillary system, where they are continuous with the ra- dicles of the veins.* Situation. — The arteries are generally situated more deeply than the veins and lymphatic vessels. Form and diameter. — The form of the arteries is more uniformly cylindrical than that of the other vessels, and their diameter, ordinarily less than that of the veins which ac- company them, diminishes in proportion as they recede from the heart; a circumstance not always observable in the veins and lymphatic vessels. Relative number. — The number of the arteries is also much smaller than that of the veins and lymphatic vessels; thus, each artery of a middle size is generally accompanied by two corresponding veins and ten lymphatics. These differences, however, only relate to the general system, and, consequently, do not exist between the pulmonary arteries and veins. Course. — In their course, the great arterial trunks, generally, follow a straight direction; the arch of the aorta and the internal carotid in the interior of the osseous canal, by which it enters the cavity of the cranium, form, how- ever, exceptions to this rule. The small arterial branches and ramifications are generally more tortuous than the veins. r Anastomoses. — The anastomoses of the arteries are less numerous than those of the veins and lymphatic vessels; and this is particularly true with regard to the arteries that have a large caliber; the ductus arteriosus, between the aor- ta and pulmonary artery, in the foetus, being the only in- stance of this kind of communication in the body. Not- withstanding, the anastomoses of the arterial system are sufficiently numerous to maintain the circulation by means * Some are still visible after they have changed from vasa efferentia into vasa afferentia. 6 34 OF THE AttTERIES. of collateral passages, after the great trunks, such as the abdominal aorta, the iliac and carotid arteries, &c. have been obliterated by the application of ligatures. Surface. — The external surface of the arteries is sur- rounded by a loose sheath which is formed by the conden- sation of the surrounding cellular tissue, and which is par- ticularly firm and dense in those parts which are subservient to locomotion. In several parts of the visceral cavities, this sheath is wanting, and its place is supplied by folds of the serous membranes. It is in this manner that the pericar- dium is spread over the origin of the arterial and venous trunks. The internal surface of the arteries is smooth and slippery, and, as we have already said, continually mois- tened by a serous exudation. At the entrance of the ven- tricles, it presents several valves, the only ones of the arte- rial system, and which we shall presently describe. The parietes are stronger in the small than in the large arteries, in proportion to the size of the caliber, hence aneurisms are much less frequent in the former. Structure. — The parietes of the arteries are formed of three cylindrical coats. External coat. — The external coat is formed by the condensation of the laminae of the cellular tissue which sur- rounds the arteries and connects them to the neighbouring parts. It admits of considerable extension, is the most re- sisting of the three, and the only one that is not divided when an artery is tied. Middle coat. — This coat, which is sometimes called the fibrous or proper coat of the arteries, is formed by a yel- low, very elastic tissue, analogous to that which is found in the trachea and yellow ligaments of the vertebras. (See hist, of the yellow fibrous tissue.) It consists of spiral fibres, which but imperfectly surround the arteries; they cross each other in various directions, and are arranged in layers that maybe easily separated. These fibres are strong, very elastic and their firmness is sufficient to maintain the OF THE ARTERIES. 35 caliber of the arteries when they are empty. The middle coat adheres more intimately to the external than to the in- ternal; and at the ventricles of the heart, it gives origin to three semi-circular festoons which correspond to the semi- lunar valves that they support. Internal coat. — The internal coat, called also the com- mon coat of the arteries, because it extends into the cavi- ties of the heart, is thicker in the arteries of the general system than in those of the pulmonary, and has no apparent fibres; it is thin and diaphanous, eminently brittle, smooth and even on its internal surface, which is lubricated, and, adhering by its external surface to the middle coat. At the entrance of each ventricle, it forms three folds, which ad- here to the circumference of the festoons that are formed by the middle coats of the arteries, and their floating mar- gins, the centre of each of which is guarded by a corpus sesamoideum,* present in the direction of the course of the blood, and meet as tense chords, describing three radii of the circular aperture of the vessel. These folds are called the sigmoid or semilunar valves, and are of use in pre- venting the return of the blood from the arteries into the ventricles. We see, from the preceding observations, that the cavi- ties of the heart are lined by a continuation of the internal membrane of the arteries, and also, that this membrane is there confounded with the venous trunks in such a manner that the heart, composed in man of two lateral halves, may be regarded as a double portion of the vascular system, which differs from the others only in that its exterior en- velopes, instead of being fibrous and cellular, are a net- work of muscular fibres. The arteries are supplied with nerves, blood-vessels and * This body serves to fill up the space which is left between the free margins of the valves, where they unite to close up the caliber of the vessels. (See the Works on Descrip. Anat.) 36 OF THE ARTERIES. lymphatics. The nerves are larger and more numerous in the arteries of the pulmonary than in those of the general system, and proportionably in the small than in the larger branches. They are derived from the great sympathetic and spinal nerves. Characters and physical properties. — The arteries are less dense and resisting than the veins, but they are thicker and enjoy a greater degree of elasticity, which is owing to their fibrous tunic. This property of the arteries is more appreciable in the direction of their length than in that of their circumference, and in the large than in the small arteries. Vital properties. — The sensibility of the arteries is very obscure; and their power of vital contractility has been denied by a number of physiologists, especially by Haller, Bichat, Nysten, and lately by Magendie, who pretends that these vessels manifest no more signs of irritability un- der the influence of mechanical and chemical agents than under that of galvanism. But the facts, recorded by Zim- mermann,Verschuir, Soemmering, Hunter, Hastings, Parry, Ginglio, Rossi and others, prove incontestibly the incorrect- ness of the opinions of those who have denied the vital con- tractility of the arteries; and at the present day, most physio- logists arc of opinion, first, that the arteries contract; se- condly, that this action is more remarkable in proportion as their caliber is smaller and their elasticity less. The contractility of the arteries is rendered evident by their beats or pulsations, which constitute what is called the pulse; a phenomenon resulting not only from the motion or slight displacement of these vessels, caused by the shock which the blood receives from the sudden impulse of the ventricles, but also from the dilatation and contraction of their parietes in consequence of the intermittent afflux of this fluid.* Each of these two kinds of movements has • By attentively observing each pulsatory motion, it can be demon- OF THE ARTERIES. 37 been considered, in its turn, as the exclusive cause of the pulsations of the arteries, but it has been demonstrated that they are the result of the combined actions of both, and that the first predominates in the great trunks, and the se- cond in the branches and ramifications. The pulsations of the arteries correspond, in general, with the contractions of the heart; and it is from these circumstances, that the pulse has furnished us with one of the most important sources of diagnosis in the examination of diseases. Its fulness, its development, its frequency, its quickness, its regularity, its equality, as well as its opposite qualities, afford us the means of judging of the danger and degree of intensity of the different diseases with which man is liable to be afflicted. In some inflammations, especially in those of a phlegmonous character, the pulsations of the arteries of the part affected, are generally somewhat accelerated, in- dependently of the actions of the ventricles. We observe also, that in paralytic patients, the pulse is more feeble in the limbs that are deprived of motion than in the other parts; another proof of the contractility of the arteries. Functions.— r-The arteries receive the blood from the heart and carry it to every part of the body. The motion of the blood is by no means uniform; each cantraction of the ventricles gives a propelling motion to its mass, which may be readily observed when an artery is divided; the blood then, it is true, will be seen to flow without inter- ruption, but by jets and jerking motions, which are syn- chronous, like the pulse, with the contractions to which we have just alluded. When the collateral branches of a large artery receive a larger quantity of blood than is natural, their calibers be- come considerably enlarged, not only by the dilatation of their parietes, but by an actual increase; for it must be re- stated that there is a simultaneous elongation and dilatation, followed by a shortening- and contraction of the arteries, 38 OF THE ARTERIES. membered, that the parietes of an artery do not necessarily diminish on account of their development. On the con- trary, the artery which has ceased to be traversed by the blood, shrinks, and is finally obliterated and converted into a kind of ligamentous cord: we shall not say that this is the result of its contractility, but a consequence of the ces- sation of its functions, the chief effect of which is, a dimi- nution in the activity of nutrition. Differences according to age. — The arteries are pro- portionably more elastic and more fully developed in in- fancy and youth than at any other period of life. In the decline of life, they lose their elasticity and become more and more brittle, and their ossification, which takes place at this period, may be regarded as a normal state, intend- ed by nature to give strength to their middle coat, which is its ordinary seat. In old age, the parietes of the great trunks are thin and brittle, especially those of the general system. Anomalies of origin. — Bichat, and since his time, Meckel and Beclard have observed that the anomalies of origin of the arteries are, in proportion to their number and volume, at least as frequent as those of the veins.* Meckel has seen ten anomalous origins from the arch of the aorta, while he has known but one from the vena cava superior. This author has made a similar remark with re- gard to the arteries and veins of the extremities. Pathological Anatomy. The arteries are subject to changes of form without lesion of their tissue. Thus, their volume may enlarge, either throughout their whole length, as parts that have been a long time inflamed, present examples,! or only in a part of * Haller, Soemmering, and the Walthers, have asserted the contrary, f In this case, the thickness of the parietes corresponds to the dilata- tion as in the deyelopment of the collateral branches. OF THE ARTERIES. 39 their extent. When the dilatation is local, (the true aneu- rism of the ancients,) it occupies either the entire circum- ference of the vessel, or, as is most frequently the case, only a part of it. The arteries are also subject to mor- bid contractions, which may be either general or partial; the first may be observed to take place, particularly in those parts where the vital action is languid and feeble; the second, more common in the great trunks, are some- times the result of a local alteration of the tissue of the ar- tery. Inflammation of the arteries is characterized by red- ness, and sometimes a thickening of their internal coat, and an effusion of coagulating lymph, which produces an adhesion of their parietes when they are brought in contact by compression, ulceration, gangrene, &c. ' The internal coat is the most subject to inflammation; the external re- sembles it in this respect, and when inflamed, it is ren- dered exceedingly brittle. Fungous growths are not unfre- quent on the surface of the internal coat, especially in the neighbourhood of the valves. There are sometimes small encysted tubercles between this and the middle coat of the arteries, which terminate either by suppuration or ossifica- tion, so as to obstruct the caliber of the vessel. Ossification, so frequent, as we have just remarked in old people,* may also be observed sometimes to occur in adults; it is often confounded with earthy concretions, which are form- ed between the middle and internal coats, and enter the caliber of the artery by penetrating its internal membrane. In consequence of the local dilatation of a part of the circum- ference of an artery, but more frequently without any pre- vious dilatation, the internal coats being weakened from the constant impulse of the blood, or altered in their texture, give way and break. The cellular coat then becomes distend- ed, and forms a tumour on the sides of the artery, with * It is to this circumstance that must be attributed the ordinary cause of the spontaneous gangrene known under the name of gangrena senilis. 40 OF THE ARTERIES. which it communicates by a ragged, and irregular open- ins. This constitutes what is termed the true aneurism — one of the most dangerous diseases of the arteries, and even of the animal economy. The ancurismal cavity contains coagula of blood, and its parietes are frequently lined with fibrous layers and pseudo-membranes. The tumour some- times remains stationary, after having attained to a cer- tain size; but more frequently it goes on gradually in- creasing, and demands the interference of the surgeon. It is seldom, indeed, that we see it diminish in consequence of spontaneous obliteration, and to induce this effect it is almost always necessary to obtain surgical aid. This dis- ease presents so many varieties, that we shall necessarily be obliged to pass some of them unnoticed on the present oc- casion. The great trunks, and the large branches, espe- cially those of the inferior extremities, are the most ordi- nary seat of this affection. False aneurism is a tumour formed by the effusion of blood into the adjoining cellular tissue, either immediately after a wound, or in consequence of the rupture of a cicatrix, (primitive false an. — consecu- tive false aneurism.) — Ligatures applied around healthy ar- teries, divide the internal and middle coats, whilethe exter- nal resists the cause of rupture, by dilating, and forms a tu- mour: — the blood is next arrested in its progress, and forms a coagulum between the ligature and the nearest collateral branch; inflammation supervenes, and at the end of forty- eight hours it determines the adhesion of the coats of the artery by means of an effusion of coagulating lymph, then the division of the tissues that embraced the ligature, its separation and removal, and finally the absorption of the clot, followed by the obliteration of the part of the artery which it filled. In cases where the external coats are bro- ken, and the internal coat alone remains entire, cicatriza- tion is also produced by the effusion of coagulating lymph, which increases the thickness of the parietes of the artery, and gives additional strength to its internal membrane; at OF THE ARTERIES. 41 other times, the internal coat is distended, forms a tumour across the solution of continuity of the others, and consti- tutes what is called the internal mixed aneurism. From the beautiful experiments performed upon dogs, by Jones and Beclard, with a view to determine the rela- tive degree of danger resulting from wounds of the differ- ent coats of the arteries, it appears, first, that a very small puncture of an artery is followed by a slight degree of hemorrhage, by the formation of a coagulum which closes up the mouth of the wound, and by a complete cicatriza- tion; secondly, that all other wounds of the arteries are fatal, if the cellular coat has been destroyed, excepting in the following cases: 1st, a longitudinal wound heals like a simple puncture, but there remains a linear cicatrix; 2d, a transverse wound embracing only one fourth of the cir- cumference of the vessel, is susceptible of healing; 3d, when it occupies one half, it is followed by too great a separation of the edges of the wound, to permit of the forma- tion of a cicatrix; it must then necessarily prove fatal; 4th, when it occupies three fourths of the vessel, it may heal, if the retraction of its extremities is sufficiently strong to ac- complish a solution of continuity; 5th, when this is com- plete, the extremities retract within their cellular sheath, and after a profuse hemorrhage, syncope ensues, a coagu- lum is formed, and cicatrization takes place. In the human subject, the treatment of wounds of the arteries has hither- to been attended with little success; both on account of the difficulty of checking the hemorrhage, and of the want of firmness in their cicatrices. Gun-shot wounds, and those resulting from severe burns, however, seldom bleed pro- fusely, the blood being retained by the eschars, which are not detached until after the obliteration of the artery. We shall say but little of lacerated wounds, in which the rup- ture of the coats of the arteries having taken place in suc- cession from the internal to the external, gives a conical form to the extremity of the vessel, which, added to the 42 OP THE CAPILLARY VESSELS. retraction by which the division of the artery is followed, presents a sufficient obstacle to the hemorrhage to allow of the formation of a coagulum. section 3. Of the Capillary Vessels. Definition. — The capillary vessels are formed by the termination of the arteries and the commencement of the veins. The smaller ramifications of the vessels take the name of capillaries the moment that their tenuity becomes such as to be invisible to the naked eye. The most delicate that can be distinguished with the aid of the microscope present the diameter of a globule of blood, which, according to the ex- periments of Messrs. Prevost and Dumas, is equivalent to the 1-2S00 part of an inch. Division. — The capillary vessels may be divided into those of the pulmonary and those of the general system; the first being between the termination of the pulmonary arteries and veins, is distributed on the surface of the air-cells of the lungs, where the blood which circulates through it is changed from venous to arterial; while the second, which is between the terminations of the aortic arteries and the origin of the veins ofthebody,is disposed in different proportions to the compound solids of the body, and the blood which cir- culates through it is changed from arterial to venous. We shall speak more particularly of the physiological functions which belong to each of these two divisions, in a subsequent part of this section. Besides the two divisions just men- tioned, there is a venous capillary system, which is form- ed by the terminations of the vena porta? and the com- mencement of the hepatic veins. General conformation. — The capillary vessels form a large and beautiful net- work in the tissues of our organs; OF THE CAPILLARY VESSELS. 43 and in proportion as they divide, they present a successive decrease in their small arterial ramifications, and a corres- ponding increase as they unite to form the commencement of the veins. Situation. — The capillary vessels are spread through- out every part of the body, and form, by their union, the most extensive part of the vascular system. Many phy- siologists, during the last centuries, have supposed that our organs were formed exclusively of capillary vessels; but this opinion has not yet been proved, nor completely re- futed, since we have no other means of proving the exist- ence of the sevessels than injection — an art which has not hitherto been fully adequate to demonstrate them in every part of the body. Inflammation, it is true, may afford us some aid in elucidating this important question, since it is attended even in some of those tissues which can not be in- jected, such as the cartilaginous, &c. with a red and striated appearance, though it is doubtful whether these striae are any thing else than simple hollow canals, formed accident- ally in the substance of the organ that is inflamed. It re- mains then for us to examine the differences which exist between the different tissues in regard to the extent and number of the capillary vessels that can be demonstrated by injection. We may arrange them in the following or- der: first, into those tissues that can not be injected, which are; — the cellular tissue, the cartilages, the epidermis and its appendages. Secondly, into those that can he but partially injected, viz: the medullary substance of the brain and nerves, the fibrous system, except the periosteum and dura mater, the serous membranes and bones; thirdly, into those that can be readily injected; these are the adi- pose vesicles, the cineritious substance and neurilema of the nerves, the nervous ganglia, the muscles, but particularly the teguments, the glands and glandiform bodies. The lungs are, of all the organs, those which are the most abun* dantly supplied with capillary vessels. 14 OF THE CAriLLARY VESSELS Mode of communication. — The beautiful and well-con- ducted experiments of Leuwenhoeck, performed upon the mesenteries of frogs, the tails of fishes and other transpa- rent organs, have fully and satisfactorily demonstrated the continuity of the arterial and venous capillaries: it has also been proved by injections, which may be readily thrown from the one into the other. The parenchymatous or spongy tissue, supposed by the ancients and some of the modern physiologists to intervene between the extremities of the arteries and the origin of the veins, has never been demon- strated, and all that has been said concerning it appears to be without foundation. We find in the reciprocal relations of the arterial and venous capillaries, the three kinds of communication, which we pointed out in speaking of anas- tomoses in general. If we examine an injected serous sur- face, whose capillaries have been carefully and minutely filled, we shall see that this system presents a complete net- work with fine meshes, in which no vessels run a distance of more than two lines without anastomosing with others. — The lymphatic vessels anastomose freely with the veins; but it is as yet doubtful whether they form any anastomoses with the arteries. Structure. — The parietes of the capillary vessels can scarcely be distinguished from the substance of the sur- rounding organs, and all our knowledge of their texture consists in the mere supposition that they are formed by a continuation of the internal membrane of the arteries and the veins. They are interwoven with nervous filaments which are derived from the cerebro-spinal system and the great sympathetic nerve; and, it is from an assemblage of these, that the papillas of the skin and mucous membranes are formed. Hypotheses of different authors with respect to the ex- istence of serous vessels, &>-c. — Boerhaave, and those who embraced the idea that our organs were entirely composed of vessels, have thought, as well as many anatomists, such OV THE CAPILLARY VESSELS. 45 as Haller, Soemmering, Bichat and Chaussier, that there was a set of vessels that were more delicate than the visi- ble capillary terminations with which they were continu- ous, and which admitted only the serum of the blood. Boerhaave even went so far as to classify them into several orders. The facts upon which this opinion rests have been drawn from the following observations: first, from the cir- cumstance that we can not form any idea of the manner in which nutrition takes place in those organs that can not be penetrated by injections; and secondly, from the fact that those parts which are naturally white, become red the mo- ment they are in a state of inflammation. Bleuland is said once to have seen a set of pellucid vessels that arose from the terminations of the arterial capillaries. — To the obser- vations advanced by the above physiologist, it will be suffi- cient to remark; first, that with the aid of a powerful mi- croscope, the terminations of the vessels can be rendered sufficiently apparent, inasmuch, that if there were even a set of vessels more minute than the capillaries, they would necessarily be rendered evident; secondly, that we can perceive the vascularity of an organ by coloured injec- tions, since the capillaries which admit only a single glo- bule of blood at the time, appear perfectly transparent; whence it is natural to conclude, that if a trasparent organ becomes red when inflamed, it is owing, in part, to the irri- tation which increases the capacity of the capillary vessels, so as to admit, consequently, a greater number of globules at the time; thirdly, that the inflammatory blush is often the result of the injection of the whole substance of an organ. In summing up the facts of the preceding observations, it will be seen, that the serous vessels have been observed but a single time, and that they ought not, from the expe- riments of Bleuland, to be considered, in the present state of our knowledge, as a separate system. Many anatomists admit the existence of extremely fine vessels, endowed with the power of transmitting from the 46 OF THE CAPILLARY VESSELS. arteries, the materials of nutrition, and of exhalation, and of other capillaries equally delicate, whose office it is to take up and carry into the veins the exhalations and organic par- ticles which are destined to re-enter the circulation. The first of these are called the exhalent and nutrient vessels, and the second the absorbejits; but the existence of these intermediate agents has never been demonstrated by ex- periment, nor the open mouths of the capillary vessels, ad- mitted by some anatomists, who have attributed to them the functions to which we have just alluded. None of these hypotheses are, however, necessary to the theory of absorption, and of exhalation; these being performed to a greater or less extent in all the tissues of the animal econo- my, and are a natural consequence of their hygromitricitL Physical and vital properties. — The capillary vessels are exceedingly permeable; their sensibility varies in the different organs in which they are found, and their con- tractility is greater and more conspicuous than in the other parts of the vascular system. Functions. — The circulation of the blood in the capilla- ry vessels is performed by the immediate action of the heart, and by their own contractile power. Having al- ready pointed out the differences that exist between the pulmonary and the general capillary systems, with regard to the change of colour which the blood suffers in traversing them, it may not be amiss to speak a little more in detail. In its passage through the capillaries of the lungs the blood is brought into contact with the atmospheric air, absorbs its oxigen, and exhales a small quantity of serosity, which is discharged during the act of expiration. Moreover, the capillaries which arise from the ramifications of the aorta, carry red blood, deposit into all the organs the materials of nutrition, losing in some of them those parts, which, be- ing separated by simple exhalation, or by glandular secre- tion, either re-enter the vascular systems (recrementitial fluids,) or are thrown off from the economy (excrementitial OF THE CAPILLARY VESSELS. 47 fluids;) then becoming venous capillaries, for the circula- tion of black blood, they absorb the recrementitial pro- ducts which result from the functions just mentioned, and, the remains of nutrition. Erectile tissue. This tissue, which Beclard and several modern anatomists, have described separately, under the name of the erectile tissue, is nothing but a variety of the vascular reticular tissue, and is formed by a net-work of veins which are continuous with the arteries, and which, by their frequent anastomoses, form cells which communicate with each other. This tissue is well developed in some of the organs, especially in the corpus cavernosum penis, the clitoris, the nymphse, the nipple, the papillae of the tegu- mentary membranes, the spleen, &c; it is plentifully sup- plied with nerves, and is supported by an elastic fibrous envelope. When its sensibility is exalted, it becomes the seat of a sanguineous fluxion, which lasts as long as the excitement that induced it continues to exist, and consti- tutes what is termed temporary erection: this phenomenon is produced in the sexual organs by the venereal desire, by degustation in the papilla? of the tongue; and by the cold stage of intermittent fevers, and a variety of other causes in the spleen. Pathological Anatomy. The caliber of the capillary vessels greatly enlarges whenever they are called to perform, by their anastomoses, the functions of an obliterated vessel. They are found every where in the accidental tissues, as in the pseudo- membranes and cicatrices, &c. In some parts, especially under the skin, they are developed so as to form masses, varying in size, configuration, and colour, resembling the vascular meshes of the erectile tissue, and, like them, are susceptible of temporary fluxion. This affection, termed te- langiectasia, or aneurism by anastomoses, is generally of a congenital nature; and is vulgarly attributed to the 48 OF THE CAPILLARY VESSELS. longing of the mother during pregnancy. To these pre- ternatural dilatations may he referred those which consti- tute what are called hemorrhoidal tumours. As soon as the capillary vessels are irritated, there is an afflux of blood which distends their caliber, and imparts a red colour to the affected tissues, whose volume becomes sensibly augmented. Sometimes these vessels are ruptured, and produce considerable hemorrhage, as the blood is ef- fused into the surrounding substance, and forms what is termed a spontaneous ecchymosis; at other times, the red- ness and swelling become more considerable; the tempera- ture of the part is elevated, and is accompanied with con- siderable pain and throbbing: this assemblage of pheno- mena constitutes inflammation — a morbid state which va- ries in its effects and termination. Inflammation of the ca- pillaries sometimes terminates: first, either in resolution, or by an effusion of lymph, which remains either fluid, or coagulates so as to form false membranes, or it combines with the surrounding cellular tissue, and gives rise to tho white induration, and to all the changes of tissue which this kind of induration is capable of producing; secondly, by an effusion of pure blood which, by its intimate union with the parietes of the capillary vessels, and the neigh- bouring tissues, produces the alteration of structure called the red induration (induration rouge;) this morbid altera- tion is often found in the lungs, organs which are essential- ly vascular, and where, from its resemblance to the sub- stance of the liver, it is called hepatization; thirdly, by the secretion of pus, possessing all the properties and dis- tinctive characters which we pointed out in speaking of the cellular tissue. Inflammation also terminates sometimes in gangrene of the capillary vessels, and of the organs in which thev are found. Fungous tumours and most of the diseases said to be organie are owing to long and constant irritation of these vessels. OP THE VEINS. 49 SECTION 4. Of the Veins, Definition. — The veins are the vessels which return the blood from the capillaries of the different parts of the bo- dy to the auricles of the heart. Division. — Besides the two trees, that correspond to those which compose the arterial system, the veins have a third, called the vena port se which is formed by the union of the veins of the spleen, and of the whole digestive apparatus, and is ramified in the substance of the liver like an artery. The general venous system may also be divided into the superficial and deep seated. General Conformation. — The veins, like the arteries, represent the figure of a tree whose trunk is the heart. Comparative situation. — The situation of the veins is generally more superficial than that of the arteries; — striking examples of this remark are afforded by the sub- cutaneous veins, and even by some of the deep-seated, as in those of the brain. Course. — The course of the veins is not so tortuous as that of the arteries — a circumstance which materially contributes to facilitate the course of the blood, which traverses most of these vessels against its own gravity. Number. — The arteries are almost universal- ly accompanied by two veins, seldom by one, which tra- verse with them the same osseous openings, and the same interstices of the soft parts. * We have already seen that the number of the veins is much greater than that of the arteries; this observation, though true in a general point of view, is not, however, applicable to the sanguineous vessels of each organ considered separately; for the intestinal ca- * In the lungs, the intestines, &c. the small veins are folded upon the arterial ramuscles with which they are continuous, and follow for a con- siderable distance their mode of "arborisation." 8 50 OF THE VEINS. nal, the kidneys, the testicles, &c, have each an equal num- ber of arteries and veins, while the penis, the clitoris, the gall-bladder, and the umbilical cord, have each two arte- ries and only one vein; in these cases, however, the size of the veins is much greater than that of the arteries and com- pensates for the inferiority of number. Origin and vol- ume. — The veins, arising in every part of the body, by in- numerable microscopic radicles, which are continuous with the arteries," 5 unite in succession and form ramifications, then branches, and finally large trunks. When two veins meet, they unite and form one that is smaller, compared with each of the original branches, than a bifurcated artery, considered in relation to one of its divisions. Sometimes, there are even veins whose caliber is not greater than the branches from which they are derived; — a kind of anomaly more common in the most dependent parts of the body, be- cause there the blood, circulating slowly and against its own gravity, exerts a greater degree of force on the parietes of the veins, naturally very extensible, in proportion as the co- lumnwhichisseparatedfromtheheart, is more considerable. Capacity. — The capacity of the venous tree is greater than that of the arterial, but not in the same proportion in every period of life; for in infancy, their capacity is nearly equal, while as we advance in life, it becomes more and more re- markable, and extremely great in old age. This difference probably exists only in the general system of the sanguine- ous vessels, and not in the pulmonary. Anastomoses. — The anastomoses of the veins are ex- tremely numerous, and may be observed to take place even between the large trunks; thus the two vense cavse commu- nicate with one another by means of the azygos. They * The transudation on the internal surface of the intestines, of the mat- ter of injection in the veins, has led to the opinion entertained by some physiologists, that there are venous radicles that originate in open mouths. The reality of this anatomical fact, however, has by no means been proved. OF THE VEINS. 51 are more frequent in those parts where the circulation of the blood is the least favoured, and where it maybe interrupt- ed by external agents, as in the subcutaneous veins, which communicate so often as to form a kind of net-work with large meshes.* There are also anastomotic communica- tions between the superficial and deep seated veins, which, according to Bichat, " are more necessary in man, than in any other animal, on account of the pressure of his clothes," &c. Form. — The veins are less uniformly cylindrical than the arteries, a circumstance which must be attributed in a great measure to the facility with which they can be distended. On the external surface of some of them there is a kind of aponenrotie rings , which correspond to the internal folds or valves, which we shall presently describe. Structure. — The parietes of the veins are thinner than those of the arteries, and like theirs are composed of three coats, which are contained in a sheath common to all the vessels. The sinuses of the brain, which, until the time of Bichat, were regarded as being entirely composed of du- plicatures of the dura mater, were proved by this great anatomist to be lined by a continuation of the internal membrane of the veins. External coat. — The external or cellular coat is less dense and resisting than that of the arteries, and when isolated, does not, like theirs, retain its cylindrical form; it is intimately united to the middle coat, in the thickness of which it sends prolongations which extend as far as thg in- ternal membrane. Middle coat. — The middle coat of the veins is so thin and indistinct, that its existence has been denied by some very able and skilful anatomists; it is most conspicuous in the subcutaneous veins and in the great venous trunks, especially in the venae cavse; is of a loose texture and is com- * The spermatic veins and those of the pelvis also present a retiform arrangement. 52 OF THE VEINS. posed of longitudinal reddish fibres, which admit of a con- siderable degree of distention, are difficult to break, as was proved by the experiments of Wintringham, and can be distinguished only in the larger veins near the heart. The middle coat appears to be wanting in the veins within the bones; and in the sinuses of the brain, its place is supplied by duplicatures of the dura mater. Its chemical compo- sition shows that it consists principally of fibrin. Internal coat. — The internal or common coat is thin, smooth, and polished, of a filamentous texture, and much more extensible and resisting than that of the arteries; it is a mere continuation of the membrane which lines the cavities of the heart, and alone constitutes the veins within the bones and the sinuses of the dura mater. On its internal surface it presents a great number of paraboli- cal folds that are called valves, whose convex edge is at- tached, and presents towards the origin of the veins, while the other, which is straight or slightly concave, is directed towards the heart. The valves are applied against the in- ternal surface of the vein by the motion of the blood that is contained in its canal: whenever there is a retrograde motion of this fluid, it escapes between the membranous folds, and the parietes of the veins, so that the valves be- come almost perpendicular to the vessel, and form a species of bag, whose cavity, being directed towards, the heart, receives the blood, and prevents its return. They are generally large enough to close the canal of the vessel; but sometimes they are imperfect, and are mere projections, or transverse bands, as we see examples in the femoral vein and in the sinuses of the dura mater. Sometimes, the veins also present anomalies, such as fissures, on their free edges, a reticular structure, &c. — anomalies which are either congenital, or, as is most frequently the case, a con- sequence of the mechanical action of the blood. They are generally found in pairs, and are placed oppositely to one another; in the smaller veins, however, they are single; or THE VEINS. 53 and sometimes, instead of two, there are three or four. The existence of the valves is generally uniform, but in some veins, as in the minute ramifications, and the great visceral trunks, they are entirely wanting; they exist chief- ly in the superficial veins, especially in those of the extremi- ties, and are more numerous and nearer each other in the small than in the large veins. They are generally found at the junction of the ramifications with the branches, and of these with the trunks. The valves prevent the retrograde flow of the blood, facilitate its progress towards the heart, and are chiefly situated in those parts where its circulation is most difficult The veins receive but a small proportion of vasa vaso- rum, and of nerves, and these are principally derived from the ganglia. The nerves which supply the pulmonary veins are chiefly from the anterior pulmonary plexus. Characters and physical properties. — The veins are of a whitish, semi-transparent colour, very extensible, and susceptible of a considerable degree of dilatation; they are less elastic than the arteries, and their parietes have not sufficient firmness to retain their caliber, when empty, unless they adhere by their external surface to the sur- rounding parts. Vital properties. — The veins enjoy but an inconsidera- ble degree of sensibility, and their contractility of texture can be distinguished only in" the larger trunks. Differences according to age. — We have already seen, that the capacity of the venous system is about equal to the arterial in infancy, but it is greater in the adult, and still more so in old age. This difference shows, that in proportion as we advance from the cradle to the grave, the circulation becomes more languid, and that the decay of our organs exceeds their growth; two causes, which by accumulating a greater quantity of blood in the veins, deter- mine their dilatation with a diminution of their parietes. Ossification and depositions of earthy phosphates, so com- 54 OP THE VEINS. mon in the coats of the arteries, seldom take place in those of the veins. Functions. — The veins bring back the blood to the au- ricles of the heart, after it has furnished the materials of secretion and nutrition, and receive the fluids which have been absorbed by the lacteals and absorbents. The circula- tion of the veins is rendered evident: first, by the pheno- mena which attend the application of ligatures, viz. by the obliteration of their caliber between the heart and the liga- ture, and their distention between this last and the venous capillaries; secondly, by the direction of the valves; third- ly, by microscopic observations. The motion of the blood in the veins is uniform and uninterrupted. The veins pre- sent no pulsations, except in those cases, where in conse- quence of impeded respiration, or an organic affection of the heart, the contraction of the right auricle causes a reflux of a portion of the blood into the vena; cavse, while the other passes into the right ventricle.* The motion exerted up- on the parietes of the veins by the blood thus repelled, constitutes the venous pulse, which can be distinguished only in the great branches, near the heart. The circula- tion of the blood in the veins is produced; first, by the contraction of the left ventricle, which has a considerable influence on the course of the blood in the veins; secondly, by the specific action of the parietes of the veins; thirdly, by the contraction of the surrounding muscles; fourthly, by the suction of the blood of the venas cavas, which is pro- duced by the dilatation of the right auricle of the heart, and is more remarkable, when, from the tendency to a va- cuum, the lungs are called into greater action. t Finally, * This reflux also takes place in health, especially during expiration, but it is not sufficient to be appreciated on the exterior of the body. fDr. Barry, in a work which he has published on the causes of the circulation of the veins, states a number of recent experiments, by which he tends to prove, that the blood traverses the veui3 only during inspiration: but it appears to us that he has exaggerated the influence OF THE VEINS. 55 the direction of the valves and the great number of anasto- moses favour the circulation of the blood in the veins. — All these causes^ however, are by no means capable of pro- ducing a force equal to that which the arterial blood re- ceives from the action of the heart, and are not sufficient completely to neutralize the laws of gravitation.* M. Magendie and some modern physiologists have per- formed a great number of experiments on the veins, and have clearly and satisfactorily demonstrated that they are absorbents. This opinion, entertained by Galen and his successors until the time of T. Bartholine, combined with that which denies to the lymphatic vessels any other office than that of mere absorbents of the chyle, will be more ful- ly discussed in the history % qf the lymphatic system. Pathological Anatomy. The veins are frequently subject to dilatations, which oc- cupy either the whole or only a part of their circumference, and constitute what are termed varices. These affections are generally produced by the pressure of the blood against the parietes of the veins, and are consequently more com- mon in those parts where the blood circulates against its own gravity, and where it is impeded in its course, as in the veins of the inferior extremities, the pelvis, &c, vari- cose veins often present a serpentine direction, which in- dicates an increase not only of their caliber, but also of their length. — Instances have been related where the whole venous system was in a varicose state, t which inspiration has on the motion of the blood, in regarding it as its essential cause, and as the cause of the dilatation of the auricles. * According to M. de Blainville, the dilatory progress of the blood in the veins, allows the elements of this fluid a longer time to favour the modifications which they undergo by their mutual reaction; modifica- tions, which are not, as has been hitherto supposed, the result of an organic action of the parietes of the vessels. f Puchelt, author of a German work on the diseases of the veins, 56 OF THE VEINS. The aneurismal varix is a tumour, arising from a pre- ternatural and direct communication between a vein and an artery. It is generally caused by wounds or by the ulce- ration of the contiguous parietes of the two vessels. When a consecutive false aneurism is formed in the intermediate tissue between two injured vessels, it is termed varicose aneurism. Morbid contractions of the veins are more uncommon than dilatations, but when they do occur, they depend most frequently, either on an obstruction of the circulation, or a chronic inflammation, which produces a thickening of their parietes, or an effusion of a plastic and membraniform matter, which lines their internal surface. In some instan- ces the venae cavae and the jugular veins are thus complete- ly obliterated, without causing an interruption of the cir- culation. This alteration may be either general or local. Wounds of the veins heal more readily than those of the arteries; and their cicatrization, though not imme- diate, is produced by an effusion of coagulating lymph, which closes up the lips of the wound. When a vein has been completely divided, the two extremities retract, like those of an artery, but the coagulum which closes up their caliber is smaller, and the part of the vessel which has ceased to perform its functions, is obliterated and con- verted into a cord. Wounds of the veins are more frequent- ly followed by inflammation and ulceration than the arteries. Ligatures applied around them divide the internal coat only secondarily, and through the medium of the inflam- mation which they create. Phlebitis or inflammation of the veins is a frequent dis- ease, and generally arises from one of the following causes; 1st, from wounds of the veins; 2d, from the application of ligatures; 3d, from inflammation of the surrounding tis- strongly insists upon this general dilatation, which, according - to him, constitutes an important character in many diseases. OF THE LYMPHATIC VESSELS. 57 sues; 4th, from a varicose state of these vessels. The anato- mical characters of inflammation, are, a considerable de- gree of redness of the internal membrane, accompanied by a thickening of the other coats; by collections of purulent matter on the external surface of the vein, and an effusion of coagulating lymph on its interior. Inflammation of the veins generally travels in the direction of the heart, and sometimes even extends as far as that organ, and destroys the life of the patient. The parietes of the veins seldom ossify, but sometimes there are small inorganic concre- tions, of the size of a millet seed, or a small pea, which occur more particularly in the veins of the pelvis, and in those where the course of the blood is most difficult. These productions, called phlebolithes, sometimes adhere to the internal surface of the veins, are commonly situated in the dilatations of these vessels, and are covered by a very thin membrane. They consist of several layers, and often ap- pear to be fibrous. section v. Of the Lymphatic System. 1. of the lymphatic vessels. Definition. — The lymphatics are small transparent ves- sels, which originate in every part of the body, and unite to form several trunks, which terminate in the general venous system. The lymphatics which arise on the surface of the intes- tines are denominated the lacteal or chyliferous vessels, while those which originate in the substance of the organs are called the true lymphatic vessels. General conformation. — The lymphatic system pre- sents rather a reticular than arborescent arrangement, and consists of a multitude of vessels which communicate with 9 58 OF THE LYMPHATIC VESSELS. each other by numerous ramifications, and terminate in two principal trunks. Situation. — All the organs, with the exception of the brain, the spinal marrow, the eye, the internal ear, and the placenta, contain lymphatic vessels. Like the veins, they are distributed in superficial and deep seated: — this arrange- ment exists not only in the extremities and in the parietes of the visceral cavities, but also in the organs that are con- tained within these last. Volume. — The volume of the lymphatic vessels is smaller than that of the veins; but in this respect they present less difference between their ramifications and branches, and remain small, notwithstanding their successive union. The lymphatic vessels of the head are the smallest in the body; those of the superior extremities are a little larger; while those of the trunk and the inferior extremities are the most voluminous. Number and capacity. — The number of these vessels is much greater than that of the veins, there being on an average ten lymphatics to a venous or arterial trunk; which accounts for the fact that their united capaci- ty is equal to that of the venous system, notwithstanding the exiguity of their volume. Form. — The form of the lymphatic vessels is that of small tubes intersected by nu- merous nodosities, which correspond to the valves on their internal surface. Origin. — The origin of the lymphatic vessels has hitherto eluded all our researches; and all the knowledge we possess upon this point, is involved in the mazes of hypotheses. The continuity of their roots with the arterial capillaries is still doubtful, and has been proved only by the single fact that matter of injection has sometimes been found to pene- trate from the arteries into the lymphatics. This pheno- menon, attested only by a small number of experiments, does seldom take place unless there be a rupture of the small arteries. Be this as it may, it is certain that the lym- phatic vessels arise in the interior of the organs, and, ac- OF THE LYMPHATIC VESSELS. 59 cording to some anatomists, on the surface of the tegumen- tary and serous membranes. The most delicate lymphatic roots that can be discovered, anastomose so frequently with each other, as to form complete meshes, sufficiently com- pact to constitute the basis of some of the organs, such as the serous and tegumentary membranes, &c. Their larger branches communicate together at more considerable dis- tances, yet their anastomoses are always more numerous than those of the veins, and present every where a reticu- lar arrangement. Course. — On the course of these vessels are found every where the absorbent or lymphatic glands, which are entered on the side remote from the thoracic duct by numerous ramifications of the absorbent vessels, termed vasa inferentia; which escape on the near side by a smaller number, termed vasa efferentia. Most of the lymphatic vessels pass in this manner through several glands, especially those of the mesentery, where these glands are more numerous than any where else; while those of the extremities run a considerable distance, and even several feet, without meeting them. Termination. — The lymphatic vessels terminate in two principal trunks; the one, termed the thoracic duct, commences at the reservoir of Pecquettii, opposite to the second lumbar vertebra, and terminates in the left subclavian vein, after having received the lymphatic vessels of the inferior extremities, the ab- domen, a great part of the thorax, the superior left ex- tremity, and of the left lateral half of the head and neck. The other, termed the vena lymphalica dextra, is formed by the union of the lymphatic vessels of the superior right extremity, by a part of the chest, and the right lateral half of the head and neck; and terminates, after a very short course, in the right subclavian vein.* A great number of * An anatomist of Florence, Doctor Rigolo Lippi, has lately discover- ed several other lymphatic trunks of a large size, and three smaller ones, terminating in the vena cava inferior, near the third lumbar vertebra; a GO OF THE LYMPHATIC VESSELS. the lymphatics terminate directly in the neighbouring veins. This fact, well known at the present day, accounts for the rapidity with which substances that have been ab- sorbed, enter the circulation. Surfaces. — The external surface of the lymphatics is uneven, and adherent to the surrounding parts; the interval is smooth and furnished with a great number of valves. Structure. — The parietes of the lymphatic vessels are composed of two membranous layers, and of the cellular sheath common to all the vessels. The external membrane is strong and firm, and from its filamentous texture, has been supposed to consist of muscular fibres; the internal is extremely thin and brittle, and forms the numerous valves which are found on the interior of the lymphatic vessels. These folds are arranged, as in the veins, either in pairs, or single, and are generally of a parabolical form, but in some of the lymphatics, as in those of the liver, they are annular. They are very numerous in the branches, and still more so in the ramifications, while there are but few in the trunks. — There is a pair of these valves at the union of the lymphatic trunks with the subclavian veins, to pre- vent the regurgitation of their contents. — The parietes of the lymphatic vessels are supplied with arteries, veins, and lymphatics, but no nerves have as yet been discovered in them. Physical properties. — In proportion to the thickness of their parietes, the lymphatic vessels have more resistance than the arteries and the veins. — They enjoy a great de- gree of extensibility, and are susceptible of retraction after death; — a fact which proves their elasticity. On these pro- perties depend the astonishing variations of volume of the lymphatics, accordingly as they are full or empty. Vital properties. — The vital contractility of the lym- fourth terminates in the primitive iliac, and some others, which are dis- tributed to the renal veins. OF THE LYMPHATIC VESSELS. 61 phatic vessels is sufficiently evident; but their sensibility is so obscure that it can be distinguished only when they are in a state of inflammation. Differences according to age. — Our knowledge of the lymphatic system is too limited to enable us to say any thing decisive with regard to the varieties of form, capa- city, &c, of these vessels, in the different periods of life. Pathological observations would induce us to believe that they are more fully developed, and enjoy a greater share of vital energy in infancy and youth than at any other pe- riods of life. Functions. — The office of the lymphatic vessels is to take up in every part of the body, and on the surfaces of all the membranes, the substances which enter the circula- tion; — to furnish the blood with the chyle and lymph, to convey them to the thoracic duct, and evacuate them in the venous system. As some of these functions, however, have been denied to the lymphatic vessels, we shall here enter into a brief detail of some of the facts that have been advanced in favour of their absorbent powers, as well as some of those of an opposite character. The ancients, who were entirely ignorant of the existence of the lymphatic vessels, regarded the veins as the sole agents of absorption. This opinion prevailed until the time of Hunter and Cruikshank, who ascribed the power of absorption to the lymphatics, which, from that period, received the name of absorbent vessels, and retained it ex- clusively until 1809. At this period M. Magendie, the celebrated French physiologist, published several experi- ments which tended to prove: 1st, that an animal would survive several days after the thoracic duct was secured by means of a ligature; 2d, that it would neither accele- rate nor retard the effects of, poison; 3d, that poison ex- posed to a surface which communicated with the rest of the body only by an artery and a vein, would prove equal- ly fatal to the animal economy; 4th, that colouring and 62 OF THE LYMPHATIC VESSELS. odorous substances could be detected in a very short time in the veins, but not in the lymphatic vessels. From these facts M. Magendie concluded, that the veins possess the faculty of absorption, that the chyliferous vessels absorb chyle only, and that the rest of the lymphatic system is devoid of this function. This manner of ex- plaining absorption was adopted by the most celebrated German physiologists, who, with M. Ribes repeated and modified the experiments of Magendie. The researches of M. Ribes led him to suppose that a certain propor- tion of the veins commence in open mouths, or in the pores of the laminous tissues of the organs, and that he saw traces of pus and fat in the venous system, while he searched for them in vain in the lymphatic vessels. In the further investigation of this subject, M. Segalas submitted poisonous substances to the action of a portion of intestine, having previously insulated it, and carefully secured its vessels, with the exception of an artery and a correspond- ing vein, which were left uninterrupted to preserve the life of the part: the presence of the poison was not evinced in the system, nor did it prove fatal to the animal until after another vein was untied. All these experiments, and others of nearly a similar nature and with the same results, gave rise to the opinion, adopted by a great number of phy- siologists of the present day, that the veins are the sole agents of absorption. The discovery of Mr. Fohmann, an anatomist of Heidelberg, of a communication of the lymphatic vessels with the veins, and of a great number of lymphatics in the lymphatic glands, and in the substance of the organs, appears to be sufficient to account for the re- sults of the preceding experiments. The important dis- covery of Dr. Lippi, and the researches of Mr. Lauth ju- nior, concur to support the observations of Fohmann. Mr. Lauth asserts, that the veins are continuous with the arteries, and that they do not, as has been supposed by some, originate in open mouths, and also that they are des- OF THE LYMPHATIC GANGLIA. 63 titute of inorganic pores; whence he concludes, that the lymphatics possess the faculty of absorption, and that there is no proof that the veins perform this function, since foreign substances, found in the blood, are carried directly to the circulation, their elimination being hastened by the numerous lymphatic branches which communicate with the veins in the interior of the lymphatic glands, and in other parts of the system. Such is the present state of our knowledge with regard to the true agents of absorption. No doubt this faculty does not belong exclusively to the lymphatics and the veins, since it takes place to a greater or less extent in all the tissues of the body. 2. OP THE LYMPHATIC GANGLIA. Definition. — The conglobate glands or lymphatic gan- glia, are small oval bodies, situated on the course of the lymphatic vessels. Form and volume. — These ganglia are more round and globular in proportion as their volume is smaller, and more flattened and elongated in proportion as it is more consi- derable. Their size varies from a lentil to that of an al- mond. Situation. — The lymphatic ganglia are found chiefly in the neighbourhood of the great joints, especially in the arm- pits, the groins, &c. but they are still more numerous in the thoracic and abdominal cavities, and, in general, in the vicinity of the lymphatic trunks and the surface by which new substances are introduced into the animal economy. Structure. —These glands appear to consist of a soft, fleshy, porous substance, contained in a membranous cap- sule, which is derived from the condensation of the cellu- lar tissue in which they are embedded: they are essentially composed of the vasa inferentia, of blood vessels which anastomose with them, and of filaments of nerves. 64 OP THE LYMPnATIC GANGLIA. Physical characters. — The lymphatic ganglia are firm and resisting, and vary in colour in the different regions in which they are found. They are of a yellowish tint in the neighbourhood of the liver, white in the mesentery, and of a dark brown colour around the bronchia and the spleen. Vital properties. — The vital properties of these glands are too obscure to be appreciated in the healthy state. Differences according to age. — The lymphatic ganglia are larger, more soft, and of a deeper colour, and enjoy a greater degree of vital energy in infancy than in the sub- sequent periods of life. In old age, they sometimes waste to such a degree, as almost entirely to disappear. Functions. — The lymphatic and lacteal vessels all pass through these glands, by which the lymph and chyle are supposed to undergo certain changes, and to begin to be mixed with the blood. They are probably also of use in entangling noxious and acrid particles, and in preventing them from entering the circulation. Pathological Jlnatomy. Congenital anomalies are frequently met with in the lymphatic system; thus the thoracic duct is sometimes double, or it splits into two branches, one of which enters' the subclavian vein, and the other the internal jugular. The lymphatics, like the veins, are subject to dilatations, which are produced by mechanical causes, and are termed cirsus. Sometimes we see a portion of a lymphatic vessel filled with a number of small vesicles which have been considered as hydatids by some authors, and have been re- ferred to alternate enlargements and contractions between the intervals of some of the valves. The lymphatic system is often affected with inflammation, which is generally slow in its progress, and gives rise to various morbid pheno- mena which may be attributed to a scrofulous diathesis. It may terminate in suppuration, the effusion of albumin- BIBLIOGRAPHY OF THE VASCULAR SYSTEM. 65 ous matter, or in the obliteration of the parietes of the vessel. The lymphatic ganglia also, present many varieties both as regards their form and situation: they are subject to in- flammation, to schirrous, carcinomatous and tubercular af- fections. Ossification,. or the deposition of earthy matter, is more frequent in these glands than in the. lymphatic ves- sels, and may be observed to occur sometimes even at a very early age. Inflammation of these glands terminates more frequently in induration than in any other tissue. Bibliography of the Vascular System. The treatises on general and pathological anatomy al- ready cited. 1°. Arteries. Haller. Oper. minor., torn. I, page 60—241. Rolando. Memoire sur la formation du Coeur et des Vais- seaux arteriels veineux et capillaires: insere dans le Jour- nal compl6mentaire du Dictionnaire des Sciences m6di- cales, torn. XII, page 34. Corvisart. Essai sur les maladies du Coeur et des gros vaisseux. Paris, 1806. Hodgson. Maladies des Arteres et des Veines, trad, par M. Breschet. Paris, 1809. , Berlin. Traite des maladies du Coeur et des gros vaisseaux, redige par J. Bouillaud. Paris, 1824. D. Belmas. Structure des Arteres, leurs proprietes, leurs fonctions et leurs alterations organiques. in 4o. Stras- bourg, 1822. Fr. Tiedemann. Tabulae Arteriarum corporis humani. Carlsruhse, 1822. Scarpa. M6moire sur l'Anevrysme, traduit par M. Del- pech. Paris, 1809. Jl. Biclard. Sur les blessures des Arteres, Memoires de la Soci6t6 medicale d'Emulation, torn. VIII, Paris, 1817. Voy. sur la ligature de 1'aorte les CEuvres chirurgicales 10 66 BIBLIOGRAPHY OF THE VASCULAR SYSTEM. de Jf. Cooper et B. Travers, traduites de l'anglais, 2 vol. in 80. Paris, 1S23. 2°. Capillaries. Malpighi. Epist. II, in oper. omn. Leuwenhoeck. Exper. et contempl. arcan. natur. detect. epist. 65 — 67. Spallanzani. Experiences sur la circulation, p. 255. Trad. de l'italien par J. Tourdes. In 80. Paris, an S. Proschaska. De vasis sanguin. capill. in disquisit. anat. physiol. organismi corp. hum. Viennae, 1812. 3°. Veins. We possess no special information on the anatomy of the veins, considered in their healthy state, but what is found in the treatises of general anatomy. On the diseases of the veins consult the following memoirs: — M. J. Bouillaud. Recherches cliniques pour servir a l'his- toire de la Phlebite, etc. , deuxieme article, Caracteres anatomiques, dans la Revue medicale, juin 1825. M. F. Ribes. Expose succinct des Recherches sur la Phl6- bite, meme recueil, juillet 1825, et Memoires de la So- ciete medicale d'Emulation, torn. VIII, 1816. M. J. Bouillaud. De l'obliteration des veines et de son in- fluence sur la formation des hydropisies partielles, dans les Arch, gener. de Med., juin 1823, pag. 188, et mai 1824, pag. 194. 4°. Lymphatics. Cruikshank. Anatomie des Vaisseaux absorbans, trad, de l'anglais par Petit-Radel. Paris, 1787. Lauth fils. Essai sur les vaisseaux lymphatiques. Stras- bourg, 1824. The persons who are desirous of having a knowledge of the recent works on the organs of absorption, will find the greater part in the following memoirs: — Magendie, Me- moire sur les organes de l'absorption chezles Mammiferes (Journ. de Physiol, exper., torn. I, p. 18,) — Voy. aussi son Precis 61em. de physiol., torn. II, pag. 179, 192 et 257. BIBLIOGRAPHY OF THE VASCULAR SYSTEM. 67 2e. edit. Paris, 1825. — Segalas. Note sur Pabsorption in- testinale. (Recueil precite, torn. II, page 11.) — Ribes. Mem. de la Soc. med. d'Emul., 18' 7, torn. VIII, p. 604 et suiv. — Tiedemann et Gmelin, Recherches sur la route que prennent diverses substances pour passer de l'estomac et du canal intestinal dans le sang, trad, de l'allemand. Paris, 1821. — Fodera, Recherches experimentales sur l'ab- sorption et l'exhalation. Paris, 1824. — Vertrumb, Mem. ins. dans le Journal complementaire du Dictionnaire des Sciences m6dicales, torn. XVI, page 225, Seller et Ficinus, Experiences sur le pouvoir absorbant des veines, meme recueil, tome XVIII, p. 318, et tome XIX, p. 125. Mard. De ^inflammation des vaisseaux absorbans lympha- tiques, dermo'ides et sous-cutanes, 2e. edit. Paris, 1824. S. Th. Soemmering. De morbis vasorum absorb, corp. hum., in So. Traj. ad Mcen. 1795. 68 OF THE SEROUS SYSTEM. CHAPTER III. OF THE SEROUS SYSTEM. SECTION 1. General Observations. Synonyma: Simple villous membranes, diaphanous membranes, &c. Definition. — The serous system consists of an assem- blage of cystiform membranous organs, insulated from each other, and presenting two surfaces; one of which is free, every where contiguous to itself and continually moistened by the exhalation of a fluid, which resembles the serum of the blood; the other rough and adherent to the surround- ing parts. Division. — The serous system is divided into two parts, the splanchnic and the synovial; the first comprehends the tunica vaginalis testis and the serous membranes contain- ed in the visceral cavities; the other the synovial mem- branes of the joints, the bursse mucosae, &c. Conformation. — The different membranes of which the serous system is composed, represent shut sacs, which may be compared, according to Bichat, to " those night caps which are folded within themselves, " The peritoneum, however, differs somewhat from this characteristic confor- mation of the serous membranes. The fallopian tubes penetrate into its cavity~, and furnish by this arrangement the only example of continuity between the serous and mucous membranes. OF THE SEROUS SYSTEM. 69 Surfaces. — The serous membranes adhere by their ex- ternal surface to the surrounding parts, very intimately in some places, and very loosely in others. Thus it is extreme- ly difficult to separate them from the lungs, the spleen and the testicles, as well as from the articular surfaces, except where they begin to be folded on themselves. The first may also be very readily separated from the subjacent parts in the neighbourhood where they pass from one or- gan to another. The external surface is somewhat rough, rugose, and covered by a layer of cellular tissue, whose density varies in the different parts of the same membrane. This surface constitutes, by its reflections, numerous folds, of which the omentum and the mesentery are well marked examples. The internal surface, every where contiguous to itself, is smooth and shining, continually moistened by a serous exhalation, and presenting numerous villi, which can be distinguished only with the aid of the microscope. Texture. — The serous membranes are formed of a sin- gle layer, whose texture is more compact in proportion as it is examined near their free surface. Their tissue may be regarded as a modification of the cellular; indeed, when a portion of serous membrane is powerfully distended, we may perceive a great number of layers and filaments, which are irregularly interwoven with each other. Besides, when the serous membranes are inflamed they become red, a character which belongs also to the cellular tissue. This, as well as the first, is the seat of a serous exhalation, whose properties are nearly of the same nature. Add to this that accidental serous membranes (cysts) are sometimes formed in the cellular tissue by its simple condensation; that, ex- posed to putrefaction, both tissues resist for a long time its action, and that their maceration is equally slow and tedi- ous. Most authors regard the serous membranes as being very abundantly supplied with pellucid vessels, which do not carry red blood in their healthy state; while Rudolph i 70 OF THE SEROUS SYSTEM. and Ribes, relying upon the results of the most minute dis- sections, assert that the serous membranes are destitute of every kind of vascularity. Characters, physical and chemical properties. — The serous membranes are white and transparent, and enjoy some degree of elasticity, which is chiefly appreciable by the facility with which they recover their original state, after they have been considerably distended. Although very extensible, they are not so much so, as the enormous distention of which they are capable in certain dropsies, would induce us to believe. It ought not to be forgotten also, that the folds which these membranes present in their healthy state, are effaced by these diseases, and that they are susceptible of considerable displacement, when the cause of distention operates only on a portion of their ex- tent. Maceration renders them opake; desication, on the contrary, increases their transparency. Subjected for a long time to the action of ebullition, they furnish gelatine and albumen. Vital properties. — In their healthy state, the serous membranes are destitute of sensibility, and that which is observed when they are inflamed, probably belongs to the subjacent tissues. Their nutrition supposes that they are possessed of some degree of vitality, inappreciable in any other manner. Differences according to age. — The serous system is extremely delicate in the fcetus: the arachnoid membrane and the omentum, which remain the most thin and delicate through life, have, in the foetus, scarcely the thickness of the parietes of a soap-bubble. The density of these mem- branes increases with the age of the individual, and is in an inverse ratio with its elasticity. In old age, the adhe- sions of these organs become stronger and more resisting, while in infancy they are loose and feeble. The serous membranes accommodate themselves to all the changes of OF THE SEROUS SYSTEM. 71 form, and the normal displacements of the organs upon which they are spread. Functions. — The serous membranes serve to line the visceral organs, and to insulate them from each other. This insulation is rendered more complete by the presence of the serum which lubricates their free surface, and which serves to facilitate the motions, and prevent adhesions of the contiguous parts. As to the separation of this fluid, Ruisch has demonstrated, that it is not derived from a glandular elaboration, as was supposed by many before his time. At the present day most physiologists are of opinion that it is a perspiratory secretion, an organic action of the serous tissue, or only of the vessels which are distributed in its texture: some very distinguished physiologists, how- ever, suppose that this texture performs no other part of the exhalation of which we are treating, than that of a hy- grometric substance.* The nature and quality of this per- spiration vary in the different kinds of serous membranes; it re-enters the circulation in proportion as it is exhaled, and undergoes probably, during this double process, a modi- fication which renders it more fit for nutrition. Bichat, in demonstrating that the extent of the serous surfaces, in- dependently of the synovial membranes, was equal to the tegumentary membranes, showed the great importance of the serous exhalations and absorptions. Pathological Anatomy. The serous membranes are sometimes thickened at the same time that their extent is increased. This phenome- non, which is often observed in hernias and dropsies, re- sults from a hypernutrition (sarcroit.) The solutions of continuity of these organs are followed by a linear cicatrix, * Rudolphi, who denies every kind of vascularity to this system, thinks that the serous exhalation is derived from the subjacent vessels, and that it traverses the serous membranes to arrive at their free surface, in the same manner as the cutaneous perspiration traverses the epidermis. 12 OF THE SEROUS SYSTEM. which is almost imperceptible when the reunion has been immediate, and by the formation of a new portion of serous membrane, when immediate reunion has not been effect- ed: this portion remains always more thin, and more ex- tensible than the rest of the membrane. The first effect of inflammation of the serous membranes is a suspension of the serous exhalation, which soon after increases, and be- comes altered in various ways. Sometimes it is changed in- to a lactescent fluid, holding in suspension small, albuminous flocculi; at others, it is of a more consistent nature and of a gelatinous appearance, and is deposited on the free surface of the membrane in the form of small particles, which are converted into layers of greater or less extent. These pseudo-membranous productions become frequently organ- ized, and establish permanent adhesions between the dif- ferent parts of the organs of which we are now treating. In cases of this kind, they at first assume the firmness of cellular tissue, and finally that of serous membrane; ves- sels may also be observed to form in their centre, and to inosculate, by their ramifications, with those of the surround- ing parts. Their mode of adhesion to the original mem- brane, as well as their disposition, their form and thick- ness, presents a great number of varieties. They are some- times found under the form of bands, filaments, fringes, &c. They are most frequent in the pleura, and the peri- toneum; and in the synovial membranes they sometimes result from the effects of rheumatism; they are liable to be converted into cartilaginous and osseous transforma- tions. It should also be observed, that inflammation some- times terminates in the secretion of purulent matter, which, according as it is more or less thick, and more or less abundant, remains spread on the free surface, or forms it- self into a collection in the most dependent parts of the cavity. The chronic phlegmasia, sometimes, convert portions of the serous tissue into the fibrous, cartilaginous and the osseous, which are ordinarily observed under the OF THE SEROUS SYSTEM. 78 form of layers, either on the adherent surface or in the thickness of the membrane. The serous surface of the pericardium often presents examples of this kind. Concre- tions of the same nature as the preceding, either pedunculous or entirely unconnected, are sometimes found in the serous cavities, and especially in the synovial. Tubercles also occur sometimes in this system. The formation of the accidental serous membranes, known under the name of cysts, is generally owing to a sub-inflammation, or at least to a constant irritation of the cellular tissue. These cysts, which have been demonstrat- ed by Bichat to be analagous to the serous membranes, mostly result from the condensation of the cellular tis- sue around an effusion of blood, a collection of matter, serum, foreign bodies, &c. &c. Some are owing to the development of a pre-existing sac, such are the cysts which result from the dilatation of the ovarian vesicles, and of the spermatic cord, produced by the partial disten- tion of the tunica vaginalis testis, &c. These cysts may present all the grades of organization of the serous mem- branes, and all the alterations to which they are subject: they exhale and absorb the same fluids. Hydatids are a kind of cysts which are distinguished from the others in this, that they do not adhere to the neighbouring parts. They are found in greater or less numbers in some organs, such as the brain, the liver, the uterus, &c. In the serous membranes, and the true cysts, they are filled and sur- rounded with serum, and appear to result from the organi- zation of this fluid: — the consistency of their parietes re- sembles concrete albumen. These productions have been placed amongst the entozoaria, by M. Laennec, who has described them under the name of acephalocystes, while Cuvier, Rudolphi and Meckel have denied them a plaee in their zoological table. The accumulation of serum in the cavities of the serous membranes — a kind of affection which constitutes dropsy, 11 74 OP THE SERO-SPLANCHNIC MEMBRANES. is owing to a want of equilibrium between the exhalation and absorption of this fluid. The first exceeds its ordina- ry tyP e > an d constitutes what is termed active dropsy; it depends most frequently on inflammation, which may be either ephemeral or chronic: when the exhalation remains normal and the absorption is languid, it is called passive dropsy, and often results from a disorder of the circulation and an engorgement of the venous system, — a frequent consequence of some deep-seated alteration of some of the viscera. section 2. Of the Sero-Splanchnic Membranes. Definition. — The sero-splanchnic membranes are those which line the visceral cavities, and cover more or less completely the organs that are contained within them. Division. — The sero-splanchnic membranes are divided into two classes; the first comprehends the tunica arach- noides, the pericardium, and the peritoneum; the second consists of the two pleura?, and the two tunicas vaginales of the testes. General conformation and arrangement. — These, like the other serous membranes, form shut sacs;* and in their general arrangement they resemble "those night caps which are folded within themselves/' in such a manner as to form an external and an internal lamina, which are continuous where they are reflected the one upon the other, and con- tiguous by one of their surfaces. The external or parietal lamina adheres to theparietes of the splanchnic cavity; while the internal or visceral lamina is spread upon the organs con- tained within it, and envelops them more or less complete- * It must not be forgotten that the peritoneum forms an exception to this general character of the serous membranes, by the fallopian tubes penetrating into its cayity. OF THE SER0-5PLAXCHNIC MEMBRANES. IO ly. It is in this sense that we distinguish the pleura eos- talis from the pleura pulmonalis, though they both form really but one serous membrane in each lateral half of the chest The arrangement of the external la3~er of these membranes presents nothing remarkable: while that of the internal is more complicated, especially in the tunica arach- noides, and the peritoneum; the first furnishing a sheath to the encephalic blood-vessels and nerves, and the second being in connexion with the various organs of the abdomen and pelvis. The parietal layer is sometimes suddenly re- flected to form the visceral, and to cover an organ that it does not ordinarily envelop completely, as for instance, in the ascending and descending portions of the colon. Sometimes, also, the membrane leaves the wall of the ca- vity, runs a short distance before it covers the organ to which it is sent, then envelops it completely, except where its blood-vessels and nerves enter, lines these, and regains the point where it was given off. From this arrangement result a number of folds, which derive their names from the organs with which they are in contact, &c. The vis- ceral layer differs considerably in its arrangement from the preceding; after having covered a part of an organ, it is extended to the parietal layer, then is reflected on itself, and envelops the other portion. The folds which are formed by the visceral layer are either loose and floating, as the omentum, or maintained firmly in their situation by the continuity of their lateral parts with the parietal layer, as is the case with the broad ligaments of the uterus. In general, the layers of the duplicatures to which we have just alluded, are connected by loose cellular tissue to permit their separation, when the organ to which they corres- pond increases in volume. Surfaces. — The external surface is every where adhe- rent to the parietes of the splanchnic cavities, to the different viscera, to their blood-vessels and nerves, and to itself in the folds of which we have just spoken: the tunica arachnoides 76 OP THE SERO-SPLANCIINIC MEMBRANES. affords the only example, and that only in a small part of its extent, where the external surface of a serous membrane does not adhere. We have already pointed the manner, in which the serous membranes are connected to the dif- ferent parts which they cover, and we have only to add, that their union is less firm and intimate where the parietal layer is reflected upon the organs. With regard to their free surface, we have nothing to add to what was said in the preceding section. Texture. — The sero-splanchnic membranes are really nothing but large meshes of cellular tissue, modified with regard to its density. Their fibrous appearance is not so well marked, nor are they so abundantly supplied with pellucid vessels, as the synovial membranes. No nerves can be traced into them, and the red vessels which appear to penetrate them, belong to the subjacent parts, and are par- ticularly numerous between their duplicatures, where there is also more or less adipose tissue. Physical and vital properties. — The extensibility of the sero-splanchnic membranes is greater than that of the synovial, but their other physical properties and their vi- tality present nothing peculiar. Functions. — In the healthy state, the quantity of fluid which is exhaled on the free surface of the sero-splanchnic membranes, is so small that it merely moistens them. It is composed principally of albumen, and when exposed to a slightly elevated temperature, most of it coagulates; ac- cording to the experiments of Beclard the incoagulable part consists of gelatinous mucus. The sero-splanchnic membranes serve to insulate the viscera from each other and the splanchnic parietes, at the same time that they fa- cilitate their reciprocal motions by the polish and smooth- ness of their free surface. They also strengthen and pro- tect a great number of blood-vessels in the visceral cavities by giving them an additional sheath, and line most of the membraniform organs. OF THE SYNOVIAL MEMBRANES. 77 Pathological Anatomy. The form of these membranes, as well as their relations with the neighbouring organs, are frequently altered by- collections of serum. These alterations are also sometimes owing to displacements of the viscera, particularly to those which result from hernias— a kind of affection to which all the organs of the abdomen, and especially the intestinal canal, are subject. The organ that passes out of the splanchnic cavity, being generally covered by a layer of serous membrane, pushes with it a portion of the parietal sac which is placed before the opening through which it escapes, and which furnishes thus a second envelope that is contiguous to the first, and constitutes the herniary sac. This sac is often formed by the distention of the parietal layer — as in cases of umbilical hernias. — The alterations of texture of the sero-splanchnic membranes having already been pointed out in the preceding section, it is only neces- sary to add, that they are more frequent in these than in the synovial membranes. section 3. Of the Synovial Membranes. Definition. — The synovial membranes are those which line the surfaces of the articular cartilages, and are inter- posed between the surfaces that move upon each other in the different parts of the body. Division. — These membranes are divided into the sub- cutaneous bursae mucosas, the synovial membranes of the tendons, and those of the articulations. Form anal arrangement of the subcut. bursae mucosse. — The subcutaneous bursse mucosse are small spherical bags, which are interposed between the skin and certain osseous parts or cartilaginous projections. They are of different sizes and firmness, and are connected to the sur- 78 OF THE SYNOVIAL MEMBRANES. rounding parts by cellular substance; they often commu- nicate with the tendinous capsules; are contiguous to them- selves by their internal surface; and some of them are di- vided into several cavities by septa, which are more or less complete.* Form and arrangement of the synovial membranes of the tendons. — The synovial membranes of the tendons may be arranged under two classes, the spherical and the vaginal. The spherical are placed most frequently be- tween the tendons of muscles, and between the tendons and some of the bones, &c. They embrace these organs more or less completely, and are veiy intimately connected to them by their external surface, which often communi- cates with the subcutaneous bursas, or the synovial mem- branes of the joints. Within some of these bursas are small folds with fimbriae appended to them, and covered by a continuation of the internal membrane of the bursas. The vaginal bursas, so called from their forming complete sheaths around the tendons, consist of two cylindrical mem- branes, which are continuous at their two extremities, and are connected to the surrounding parts by cellular sub- stance. In some regions, one of the extremities of these tendinous sheaths is divided into several portions in the form of small bands, which are continued upon different tendons. Form and arrangement of the synovial membranes of the articulations. — These membranes form shut sacs of the finest texture, are of a spherical form, and line the sur- faces of the diarthrodial joints, their ligaments, and the parts which immediately surround them. Their number, form and arrangement, differ in the different joints; thus in some of the articulations, such as the ileo-femoral, the synovial capsule is reflected upon the inter-articular liga- * To Beclard is due the honour of having given the first good descrip- tion of these small organs. OF THE SYNOVIAL MEMBRANES. 79 ment, which gives it a kind of vaginal appearance. In the knee-joint, its reflections are still more complicated on ac- count of the great number of ligaments, and the tendons to which it furnishes more or less complete sheaths. The synovial membranes adhere to the ligaments and perios- teum, which they cover in such a manner that they can not be separated without difficulty: and their connexion with the articular cartilages is so intimate that they scarcely ad- mit of being detached; so that several anatomists, and amongst others, M. Magendie, have denied its existence in the central portions of the cartilages; but a careful ex- amination, as well as facts derived from pathological anato- my, such particularly as pseudo-membranous adhesions on the centre of the articular surfaces, will at once convince us of the incorrectness of the opinions of those who would deny its existence. The synovial membranes of the joints have loose folds which are analagous to those of the sero- splanchnic membranes, and are called fimbriated pro- longations. These duplicatures contain cellular tissue and blood-vessels, as well as small masses of fat, which Havers improperly described as glands, and which have been named by his successors in honour of him, glandulse Haveri. Texture. — The tissue of the synovial membranes, es- pecially that of the first two varieties, can be distinguished from the cellular tissue only by its greater density. Some of the synovial membranes of the joints appear to have lym- phatic vessels; but no nerves can be traced into any of them, and their vessels, which do not carry red blood in the healthy state, can be seen only when they are inflamed. Characters and physical properties. — All the synovial membranes are whitish, semi-transparent, soft and thin; and their sensibility appears to be less than that of the sero-splanchnic membranes. Vital properties. — The vitality of the synovial mem- 80 OF THE SYNOVIAL MEMBRANES. branes, like that of the other serous membranes, is ren- dered evident only by inflammation. Differences according to age. — The subcutaneous bursas can easily be distinguished at the period of birth; their synovia being then more abundant than at any other period of life. Their extent and density augment, in proportion as the parts where they are found are exercised. Accord- ing to the observations of Beclard, Bogros, Breschet, and Villerme, the synovial membranes of the tendons are de- veloped subsequently to the friction of the tendons of the neighbouring parts. They are formed, indeed, in every part where the skin becomes the seat of habitual pressure, as for instance, in the stumps of amputated limbs. Soem- mering observes, that the bursas diminish in number as we advance in life, by uniting with those with which they are contiguous. Finally, the synovial membranes, very fine and delicate in the foetus and infant, become more dense and compact in the adult; in old age, they acquire a certain degree of rigidity, exhale less synovial fluid, are dry, and contribute not a little by the state in which they are, to the slowness of motion which marks this period of life. Functions. — The synovial membranes serve to facilitate the reciprocal motions of the parts between which they are situated, both by the smoothness of their surface, and the presence of the synovial fluid, which is constantly ex- haled and absorbed. This fluid is more abundant on the fimbriated prolongations, and is derived from the numer- ous blood vessels which are distributed between the reflec- tions of these membranes, and not, as was said by Havers, from the elaboration of a glandular apparatus. The syno- vial fluid exudes from every part of the free surface of the synovial membranes — a fact, which in itself is sufficient to overthrow the hypothesis of Haver:,. — It differs both in quantity and properties in the different kinds of synovial membranes. In the bursas mucosas it is merelv sufficient OF THE SYNOVIAL MEMBRANES. 81 to lubricate the membrane, and to render it unctuous to the touch; in the tendinous pouches, it is more abundant, of a thick viscid consistence, and of a yellowish red tint, composed of albumen and mucus. In the articular mem- branes it is equally viscid and ropy, of a saline taste, com- posed of water, albumen, fibrin, mucus, of some of the salts of soda and lime, and, according to the analysis of Fourcroy, of a small quantity of uric acid. Pathological Anatomy. Dropsy of the subcutaneous bursas, {hygroma), and of the synovial sheaths of the tendons (ganglion) is by no means a rare disease; while that of the articular synovial membranes (hydrarthrosis) is seldom found to occur. The synovial fluid sometimes accumulates in considerable quantities, and preserves its normal character; at others, it is altered in various ways. In the first two varieties, it fre- quently resembles currant-jelly, both in colour and consist- ence. Inflammation of the synovial membranes often ter- minates by the secretion of puriform, or purulent matter, produces ulceration, or fungous growths, and converts the articular capsules into a gray striated, pultaceous substance,, which gradually invades the whole joint. It also some- times terminates in a thickening of the membranes, and in the formation of pseudo-membranous adhesions, which vary in form like those of the other serous membranes. Some- times there are small bands, or cords, which, by their num- ber and direction, represent a kind of cellular appearance; at others, there are membraniform layers which unite the free and contiguous surfaces, and produce permanent ad- hesions. All these affections impede the motions of the parts between which the membrane is interposed, and con- stitute a variety of false anchylosis — a disease which also frequently results from a thickening and induration of the articular synovial membrane and the adjacent tissues. When the contiguous parts of a joint adhere, the synovial 12 82 BIBLIOGRAPHY OF THE SEROUS SYSTEM. capsule and the articular cartilages are gradually absorbed; the extremity of the bones unite, and constitute what is termed true anchylosis. Foreign bodies, such as cartila- ginous concretions, &c, are not unfrequent in the synovial membranes, especially in those of the tendons, which also, now and then, contain small bodies of the size and shape of a pear-seed, which have been falsely supposed to be en- dowed with life. — The synovial membranes of the joints are sometimes subject to fibrous, cartilaginous, and osseous concretions, which are either loose, or adherent, or lodged in the thickness of the articular cartilage; — saline concre- tions, composed principally of the urate of soda, are some- times found in the articulations; and under certain circum- stances new synovial membranes are formed, especially between the fragments of a broken and disunited bone. Bibliography of the Serous System. 1. Sero-splanchnic system. Bichat. Traite des Membranes. Paris, an VIII; pag. 73; III, 202—292. Anatomie generale, torn. IV, pag. 108 et suiv. edit. citee. J. F. Meckel. Ouv. cit. P. Ji. Bkclard. Ouv. cit. Bonn. De continuationibus membranorum. Amst. Batav., 1763. Langenbeck. Commentarium de structura peritonii, etc. cum tabulis. Gottingen, 1817. 2. Synovial System. Fourcroy. Six Memoires pour servir&l'Hist. anatom. des Tendons, dans lesquels on s'occupe specialement de leur caps, muq,; dans les Memoires de l'Acad. royale des Sciences. Paris, 17S5 — SS. Koch et Eysold. De bursis tendinum mucosis. Witten- burg. 1789. BIBLIOGRAPHY OF THE SEROUS SYSTEM. 83 Ch. M. Rosenmuller. Icones et descript. bursar, mucos. corp. hum. Leipsig, 1799. Jl. Hdvers. Osteologia nova. Londres, 1691. Brodie. Traite des maladies des Articulations. Paris, 1819. Margueron. Annales de Chimie, torn. IV. J. Cloquet. Notes sur les Ganglions. (Arch, gener. de med., torn. IV, pag. 23.2.) S4 OF THE FIBROUS SYSTEM. CHAPTER IV. OF THE FIBROUS SYSTEM. FIRST DIVISION. OF THE FIBROUS SYSTEM, PROFERLY SO CALLED. SECTION 1. General Observatio?is. Synonymu: Albugineous tissue, tendinous tissue, aponeurotic tissue, ligamentous tissue. Definition. — The fibrous system consists of an assem- blage of organs, which present various forms, serve differ- ent purposes, but are all composed of a white shining tis- sue, which is firm and strong, and consists of more or less distinct fibres. Division. — The fibrous tissue, may be distinguished in- to several classes: 1st, into the fibrous ligamentous or- gans, which comprehend the tendons and the ligaments properly so called; 2d, into the fibrous envelopes, which consists of the aponeuroses of the muscles, the periosteum of the bones, the perichondrium of the cartilages, the dura mater of the brain, the sclerotica of the eye, the tunica albu- ginea of the testis, the glandular coverings, &:c. &c. General conformation. — There are two principal forms in the fibrous system, the fascicular and the membranous; the first belongs exclusively to the tendons and the liga- ments; the second to the fibrous envelopes, and in part, also OP THE FIBROUS SYSTEM. S5 to the ligaments and tendons. From the fact, that the ten- dons, the ligaments and aponeuroses, as well as the dura ma- ter, and the fibrous envelope of the corpora cavernosa, are connected with the periosteum, Bichat has represented this membrane as the basis of the fibrous organs; but as some of the glandular envelopes, which belong, like the preceding organs, to the fibrous system, have no relation of continuity with it, we are not warranted in admitting this distinction. Texture. — All the fibrous organs are composed of an assemblage of fibres, which are more distinct in some parts than in others; they are either disposed in fasciculi which are almost parallel with each other, or they are inter- woven in different ways, and form thin and cross layers, as in the aponeuroses. These fibres consist of white fila- ments which are more fine and delicate than hairs, and enjoy all the physical properties which belong to the tissue which they compose. In his classification of the elementary tissues, M. Chaussier has applied the name of albugineous fibre to the tissue of which we are treating; but most phy- siologists of the present day, consider it as merely a very condensed variety of the cellular tissue. This tissue surrounds and connects every fasciculus, every fibre, and furnishes a sheath, or covering to the organs which they form. No nerves have as yet been traced into the fibrous tissue; it contains but little adipose substance, and its degree of vascularity differs in the different classes of fibrous organs; thus the periosteum and the dura mater are abundantly supplied with blood-vessels, while some of the tendons, especially the large ones, appear to be destitute of them. There are some, which receive lym- phatics. Characters, physical and chemical properties. — The fibrous tissue is of a brilliant white, argentine colour, firm and resisting, and stretched with difficulty. When this, however, takes place suddenly, the cause of resistance is sometimes overcome, and the organ is torn; often, howev- S6 OP THE FIBROUS SYSTEM. er, this resistance is greater than that of the bones &c, to which it is attached. The fibrous tissue, having but little ex- tensibility, is sometimes subject to accidents, known under the name of strangulations, which consist in the insupe- rable obstacle which the fibrous organs present to the de- velopment of the parts which are ordinarily surrounded by them, and whose volume is suddenly augmented by violent inflammation or other causes. It possesses but lit- tle elasticity, at least in its fresh state; it retracts with a degree of slowness proportionate to that of its distention. By desication, it becomes somewhat elastic, transparent, of a yellowish red colour, and almost homogeneous; but by submitting it to the action of water, for a short time, it re- covers all its original characters. After long maceration, its fibres separate, and are changed into a soft, whitish pulp, which, by the action of ebullition, is resolved into gelatine. It is very difficult of digestion, and when expos- ed to putrefaction, it resists its action for a considerable time. Vital properties. — In the healthy state, the sensibility of the fibrous tissue, as we have already seen, is rendered evident by violent distentions, such as sprains, which pro- duce excessive pain, and often give rise to the most in- tense inflammation.* Nevertheless, if a fibrous organ be punctured, divided, or submitted to the action of chemical irritants, the animal will not evince the least symptom of pain: though sometimes, these causes may be capable of acting upon this tissue in such a manner as to excite in- flammation. The fibrous tissue is destitute of contractility of texture; and when injured, it is often readily repaired. Mode of development, and differences according to age. — The fibrous tissue can be distinguished about three months after impregnation: in the infant, it is of a pearly, * Many persons, and we amongst the rest, believe, contrary to the generally received opinion, that this pain ought to be attributed rather to the nerves of the injured part, than to the ligaments themselves. OP THE FIBROUS SYSTEM. 87 white appearance, and yields readily to the extensive mo- tions which are performed at this period, and being more extensible, it breaks less easily. At this period, the peri- osteum, the dura mater, and the sclerotica, are .compara- tively more developed than in the subsequent periods of life. In old age, the fibrous tissue becomes more compact and inflexible, more yellow and less shining than in the adult. Notwithstanding its hardness, it seldom ossifies, except in those regions where it is exposed to the friction of the bones, or in the neighbourhood of the cartilages. Functions. — The functions of the fibrous system vary in the different fibrous organs, and are all purely me- chanical. pathological Jlnatomy. When a fibrous organ has been extended, it becomes elongated and thickened, and with difficulty recovers its former state. Wounds of these organs heal by the effusion of adhesive matter which closes up their lips, and acquires the density of fibrous tissue. Inflammation seldom termi- nates in gangrene or suppuration, but most frequently by resolution or a thickening of the organ. The chronic phlegmasia? of the fibrous organs often produce cartilaginous and osseous growths, the development of fungous polypi, and carcinomatous tumours. The fibrous tissue is some- times accidentally developed around cysts, tumours, false anchyloses, and in the pseudo-membranous adhesions of the serous membranes. The cicatrices of the liver and the skin consist of a tissue analagous to the fibrous, and the development of some polypi and subcutaneous tumours, especially those that occur between the rectum and the vagina, and between it and the bladder, may also be refer- red to it. Fibrous bodies are also sometimes found in cer- tain parts of the body, especially in the uterus and the ovaries, which are often confounded with schirrus, though they are entirely different. They are more or less numer- ous, are round and lobulated, small and soft, and gradually 88 OF THE FIBItOUS SYSTEM. increase in volume and density. They arc formed of two layers; one of which is fibrous, the other of a homogeneous texture, and consists, according to the researches of J. F. Meckel, of fibro-cartilage. They are frequently organized, and are sometimes converted into cartilaginous and osseous substances: the calculi which occur in the uterus are often nothing but lobes of these bodies'. SECTION 2. Of the Organs Co7?iposing the Fibrous System, Pro- perly so Called. ARTICLE 1. Of the Fibrous Ligamentous Organs. The fibrous ligamentous organs comprehend the liga- ments of the bones and cartilages, and the tendons which unite the muscles to the hard parts. § 1. Of the Ligaments. Definition. — Ligaments are strong fibrous organs, \2.vy- ing in form, and adhering to the bones or cartilages. Division. — The ligaments are divided according to their situation: 1st, into articular, or those which are attached to the ends of the articulating bones; 2d, into non-articu- lar, or those which pass from one part of a bone to ano- ther, either to convert a fissure into a foramen, as the coraco-acromion ligament of the scapula, or to obliterate an osseous aperture, as the sub-pubic ligament, for the pur- pose of giving origin to muscles; 3d, into mixed, or those which supply the place of bones, and increase the extent of surface for the attachment of muscles; as the inter-os- seous peroneo-tibial, the radio-cubital, and the saero-sciatic ligaments. OF THE FIBROUS SYSTEM. 89 Conformation and arrangement. — All the different classes of ligaments have the two general forms of the fi- brous organs, the fascicular and the membranous. The fasci- cular ligaments are generally of an irregular quadrilateral form, seldom triangular, composed of white fasciculi, ar- ranged in parallel lines, and connected by cross fibres. The articular ligaments are termed external or internal, accord- ingly as they are situated in relation to the joint. Most of the external ligaments are situated laterally, and in such a manner as to confine or prevent lateral motion; internally they adhere to the synovial membrane, externally to the tendons, &c. which surround the joint. The internal liga- ments are white fibrous cords, which are situated within the knee and the ilio-femoral articulation, and are attached by their extremities to the centre of the articular surface, and adhering in the rest of their extent to the synovial membrane, which is reflected upon them so as to form a sheath. The membranous ligaments vary in form, and are composed of distinct fasciculi, which are more or less inti- mately connected with the periosteum. The capsular liga- ments form large fibrous sacs, which surround some of the moveable joints, and are attached by each of their extre- mities to the circumference of the osseous parts, which enter into the composition of the joints. They adhere firmly by their internal surface to the external surface of the synovial membrane, and by the other, to the peri-articular tissues. In infancy, the ligaments are almost exclusively inserted into the periosteum, and their connexion with the bones and cartilages is loose and feeble, while it becomes more firm as we advance in years, and extremely intimate in old age. Texture. — The ligaments are of a firm compact texture, of a yellowish colour, and composed of fibres which are more distinct in some than in others. They receive blood- vessels and lymphatics, and have a small quantity of fat, 13 90 OF THE FIBROUS SYSTEM. which it is difficult to distinguish at first sight. They pos- sess but a small share of elasticity and sensibility, though according to some anatomists, nerves may be traced into their substance. Functions. — The functions of the ligaments differ in the different classes of ligaments; thus the articular liga- ments connect the extremities of the moveable bones, while the non-articular and mixed serve to convert certain bony fissures into foraminse, and to increase the extent of surface for the attachment of muscles, &c. Alterations. — The ligaments, especially the capsular, are often ruptured, — inflamed, — relaxed, — thickened, — reduced to a lardaceous spongy substance, and ossified. § 2. Of the Tendons. • Definition. — The tendons are the fibrous, ligamentous organs, which unite the muscles to the bones or cartilages, or even two portions of the same muscle. Division. — They are divided according to their form, into funicular and aponeurotic tendons. Situation and relations. — The tendons are most com- monly situated at the extremities of the muscles, and are connected to them by one extremity, and by the other to the bones, or the aponeurotic envelopes. The tendons sometimes interrupt the continuity of the fleshy fibres, and give the muscle a digastric appearance, &c. In some in- stances, the funicular and aponeurotic tendons occur on the same muscles, and when this is the case, the first is attach- ed to the more moveable part, and the second to that which serves as the fixed point. The union of the tendons with the fleshy fibres is every where firm and intimate. In some places the muscular fibres run from both sides obliquely downwards or upwards, to a tendon in the middle of a muscle and form an arrangement analogous to the plumage of a feather; or the tendinous fibres follow the direction of OF THE FIBROUS SYSTEM. 91 the muscular, with which they appear to be continuous. In some instances the tendons are more or less completely surrounded by synovial bursas; are contained in fibrous sheaths, and are in relation with loose cellular tissue. Conformation. — The funicular tendons are elongated, rounded or flattened cords, some being single in their whole extent, others divided at one of their extremities into several distinct portions. The aponeurotic tendons, like the funicular, are either single or divided; in some in- stances they form arches for the passage of blood-vessels and nerves, and are inserted by their extremities into the bones; others are partly funicular, and partly membrani- form. In some instances the muscles terminate in very short, separate fasciculi, which are connected to one or the other kind of tendons to which we have just alluded. Texture. — The tendons are of a firm compact texture, are composed of condensed cellular tissue, and their fibres, which are white and small, are intimately united to each other by cellular tissue. They have but few blood-vessels, and neither nerves nor lymphatic vessels have been traced into their substance. Characters, physical and vital properties. — The ten- dons are of a pearly white appearance, dry, tough, and inextensible; their vitality, especially that of the funicular, appears to be less than that of the other fibrous organs. Functions. — The tendons serve to unite the muscles to the bones and cartilages, and, by atfording a more exten- sive surface of insertion to the muscular fibres, to facilitate their action. Alterations.— The tendons are seldom inflamed; but when they are bruised or otherwise injured, they become affected with indolent swellings, which continue for a long time. They participate in the softing of the ligaments in cases of white swelling, and when exposed to the air and deprived of their cellular tissue, they mortify and exfoliate. 92 OF THE FIBKOUS SYSTEM. ARTICLE 2. Of the Fibrous Envelopes. The fibrous envelopes comprehend: 1st, the aponeuroses, or fibrous envelopes of the muscles; 2d, the sheaths of the tendons; 3d, the periosteum; 4th, the perichondrium; 5th, the dura mater, the sclerotica, albuginea, &c. &c. § 1. Aponeurotic Envelopes. Definition. — The aponeuroses are fibrous membranes which cover more or less completely one or more muscles. Division. — They are divided into general and partial; the first belong to the extremities, the second to the trunk. Conformation and arrangement. — The general enve- lopes represent the form of the extremities whose muscles they surround. By their internal surface they are in con- tact with the muscles, and send membranous elongations between them, which, in separating them from each other, furnish points of attachment to some of their fibres, and go to be inserted into osseous eminences. The external surface is united by loose cellular substance to the tegu- ments, the adipose tissue, and the subcutaneous vessels. At their extremities, the general aponeuroses are confound- ed with the periosteum or cellular tissue, and form fibrous rings for the passage of tendons. The partial aponeu- roses vary in form, and serve to envelop but incompletely the muscles of the parietes of the splanchnic cavities. There are some which cover but one muscle, as the tem- poral, while others envelop several; some correspond by their internal surface to the muscles which they cover, and by the external to the subcutaneous cellular tissue: others are in contact with the muscles on both surfaces, and consist of several layers which contain these muscles OF THE FIBROUS SYSTEM. 93 between them, as in a kind of pouch; an example of which is seen in the aponeuroses of the recti muscles of the ab- domen. The aponeuroses have generally one or more tensor muscles that are inserted into them, either in whole or in part, which are destined to give them a degree of tension or relaxation proportioned to the state of the surrounding muscles. This arrangement is remarkable in the insertion of the tensor vaginas femoris into the fascia lata of the thigh; of the biceps brachialis into the anti-brachial apo- neurosis, &c. Texture. — The aponeurotic envelopes- are composed of one or more layers of fibres, which pass in various direc- tions. Physical characters. — The aponeurotic envelopes are of a pearly white appearance; their thickness is in direct ratio with the number, force and activity of the muscles which they envelop. Their fibres are more inflexible and resisting than those of the tendons, and yield less readily to maceration and the action of ebullition. Functions. — The aponeuroses serve to maintain the subjacent parts in their natural situation; to cover and in- sulate the muscles; to facititate the circulation of the ven- ous and lymphatic fluids, and, by their want of extensibi- lity, to prevent their accumulation. § 2. Of the Tendinous Sheaths. Definition. — The tendinous sheaths are the expansions of the fibrous tissue, which form, either alone, or in con- junction with the neighbouring parts, a kind of canal for the passage of one or more tendons. Division. — The tendinous sheaths are divided into gene- ral or partial, according to the number of tendons which they receive. Situation. — The tendinous sheaths are seen principally in the extremities, especially in the sense of flexion — a dif- 94 OF THE FIBROUS SYSTEM. ference which is owing to the number of flexor muscles being greater than that of the extensors. Thus, besides the strong sheath which the flexors of the fingers have in com- mon with each other, each of them receives a proper one, while the extensors are maintained in their proper place merely by some of the tendinous fibres of the interoseous muscles. Form and arrangement. — The sheaths of the tendons are so arranged, that some of them form complete canals for the passage of the tendons, while others form only a part, the other part being formed by the bones which give insertion to the extremities of the tendinous sheaths. In some instances, they form true canals, while others consti- tute only a kind of rings, and are hence called annular ligaments. When these sheaths receive more than one tendon, they are either simple or compound, that is, they are divided by fibrous prolongations into as many canals as there are tendons. They are continuous with the aponeuroses of the extremities where they are found. Their internal surface is lined by a vaginal synovial pouch, which, in the compound sheaths, sends reflections between the tendons, so as to form more or less complete septa. Texture. — The tendinous sheaths are of a very dense and compact texture, and are composed of transverse or oblique fibres, which are more apparent in some than in other places. Functions. — They give strength and firmness to the tendons, maintain them in their proper situation, and di- rect their force. § 3. Of the Periosteum. Definition. — The periosteum is the fibrous envelope of the bones. Form and arrangement. — This membrane represents the form of the bones which it surrounds and covers. It is wanting on the cartilaginous surfaces of the moveable OF THE FIBROUS SYSTEM. 95 joints where its continuity is of course interrupted; in the immoveable articulations it passes without interruption from one bone to the other. — In infancy it is thick, and can be easily separated from the bones; while in the adult it is more firm and compact, and is intimately connected with the short bones and the extremities of the long ones, and, in short, every where, where they present a spongy texture. The periosteum gives off numerous prolonga- tions which accompany the vessels that enter every where the spongy substance of the bones. Texture. — The direction of the fibres of the periosteum is analogous to that of the long and the short bones; but its arrangement is different in the flat bones. It receives a great number of blood-vessels, and some lymphatics; and when subjected to continued pressure, it is converted into a fibro-cartilaginous substance. Differences according to age. — In the foetus, the perios- teum is soft and spongy, moistened by a gelatinous fluid, and possessed of but little vascularity. As we advance in years, its fibres become more* distinct, and the membrane ' increases in firmness, consistence, and vascularity; in old age, it has extreme tenacity, and even becomes ossified on its internal surface. Functions. — The periosteum defends the bones which it covers from the impression of the organs that move upon its surface, and strengthens the parietes of their vessels. In infancy, it unites the epiphyses to the bodies of the bones, and serves for the insertion of the ligaments and tendons, which subsequently and in consequence of the os- sification of this membrane at their points of attachment, adhere to the bone itself. Pathological Jlnatomy. Wounds of the periosteum are followed by a cicatrix which resembles it in texture, and when a small portion of it has been raised or detached, it is generally reproduced. 96 OP THE FIBROUS SYSTEM. Inflammation of this membrane seldom terminates in gan- grene, but most frequently in suppuration, which detaches it from the bone, and has a tendency to produce periostosis, osssification, soft cancer, and the development of fungous growths, § 4. Perichondrium. The perichondrium is the fibrous membrane which covers the non-articular cartilages; it is less intimately connected to them, than the periosteum is to the bones, and does not send to them as many fibrous elongations. It contains fewer blood-vessels than the periosteum, has less vitality, and diners from it also in some of the characters which we have just pointed out. § 5. Of the fibrous envelopes of the brain, the spinal marrow, and some other organs. These membranes are, 1st. The dura mater, (meninx of Chaussier), a very dense, and vascular membrane, composed of tendinous-like fibres, running in various di- rections, and situated within the cranium and the ver- tebral canal, to the former of which it forms an internal peri- cranium. It is intimately united with the tunica arachnoides, covers the brain and spinal marrow, and sends elongations in the form of sheaths upon the nerves which pass out at the base of the cranium, and through the verte- bral holes. This membrane forms a number of folds or duplicatures within the cavity of the cranium, which may be distinguished into those which separate the different parts of the brain, as the falx major, the tentorium cerebelli, and the falx minor; and into the sinuses of the dura mater, or those which perform the offices of veins, and are lined by a continuation of the internal membrane of the veins. 2d. The sclerotica, an opake, white, elastic, fibrous membrane, of unequal thickness, possessed of little vascu- OF THE FIBROUS SYSTEM. 97 larity, and serving as a covering to the eye, determining its shape and supporting and defending the more delicate and useful parts within it. 3d. The tunica albuginea, a strong, dense, in-elastic membrane, varying in thickness, possessed of but little vascularity, and serving to surround and defend the testes. — Under this head may also be included the fibrous en- velopes of the ovaries. 4th, and lastly, the fibrous capsules of the kidneys, which surround them, and send prolongations into the interior of their substance. It remains to bs remarked, that none of the organs which are surrounded by coverings of the non-elastic fibrous tis- sue, are destined to undergo any temporary changes of volume, as are those which are surrounded and enveloped by the elastic fibrous tissue. § 6. Of the fibro-serous and the fibro-mucous mem- branes. Every where, where the fibrous membranes are found in relation with the serous or the mucous, they are so firm- ly united to them, that it is impossible to separate them by dissection; so that they appear to form a single membrane, fibrous on its external, and mucous or serous on its inter- nal surface. The pericardium and the tunica vaginalis, are, in a part of their extent, true fibro-serous membranes; the union of the dura-mater and the arachnoides is also very intimate every where, where these envelopes are applied, the one upon the other. We see examples of the fibro- mucous membranes in the trachea, where the fibrous tunic is inseparably united with the mucous; in the periosteum and perichondrium, wherever the internal teguments lie immediately upon them, as in the nasal fossae, the meatus auditorius externus, the larynx, &c. 14 98 OF THE FIBROUS SYSTEM- SECOND DIVISION. Yellow elastic fibrous System. Definition. — This system comprehends a great number of membranous, ligamentous parts, &c, formed of a tissue analogous to the preceding in texture, but differing from it by its great elasticity. Situation. — This tissue is found in every part of the body, where it is necessary that there should be a continu- al or intermittent resistance to the impression of weight, to the action of the muscles, &c. In the human subject, the principal organs in which this tissue occurs, are, the yellow ligaments of the vertebrae, the proper coats of the vessels, especially those of the arteries, the excretory and aereal ducts, the covering of the spleen, and of the corpora cavernosa.* Conformation. — The fibrous elastic tissue is found un- der three forms; 1st, under that of fasciculi, as in the yel- low ligaments; 2d, under that of tubes, as in the vessels and excretory ducts; and 3d, under that of membranous capsules, with interior reticular elongations, as in the cov- erings of the spleen, and the corpora cavernosa. Structure. — This tissue is formed of fibrous fasciculi, parallel with each other, or nearly so, but never interlac- ed, and easily separable; it contains little cellular substance and but few vessels. Characters, physical and chemical properties. — In the living subject, the elastic fibrous tissue is firm and opake, and of a white yellowish colour, which becomes more dis- tinct after death; it has less tenacity, and more extensibili- ty than the other fibrous tissue, is more tenacious than the * In quadrupeds, this tissue constitutes the ligamentum nucha:, or the posterior cervical ligament, and the ligament which is inserted into the claws of some of the feline species. OP THE FIBROUS SYSTEM. 99 muscular, in the dead than the living subject, and bears a greater resemblance to it, than the preceding tissue. It contains a great quantity of water, upon which depends its most remarkable physical property — elasticity — by vir- tue of which, it immediately recovers its original state, when it has been distended or compressed. When this tis- sue is dried, it loses half its weight, and assumes a cor- neous appearance, but a few days maceration is sufficient to recover its elasticity and original characters. The yellow fibrous tissue resists for a long time the ac- tion of boiling water, the acids and alkalies; and macera- tion scarcely produces any alterations. — It is composed prin- cipally of albumen and fibrin. Vital properties. — This tissue appears to have neither sensibility nor contractility. Functions. — The yellow fibrous tissue serves the pur- pose of ligaments or envelopes to certain organs, yields by its extensibility to their changes of volume or situation, and recovers its natural form as soon as the cause, which in- duces these changes, has ceased to act. Pathological Jlnatomy. — The anatomical history of the diseases of this tissue, having been included under that of the fibrous tissue, properly so called, we shall only remark here, that this tissue very seldom ossifies, and that it has a tendency to lose its elasticity from too frequent, excessive, or continued distention. THIRD DIVISION. Fibrocartilaginous System. Definition. — This system comprehends those organs, which, by their texture and tenacity, participate in the cha- racters of the fibrous tissue, and by their density and whiteness in those of the cartilages.* , * Bichat has placed in this system the membraniform cartilages which 100 OF THE FIEROIJS SYSTEM. *"*» Division. — The fibrocartilaginous organs are distin- guished; 1st, into the inter-articular, or those which are free on both surfaces; 2d, into those which have one sur- face free and the other adherent; these are the fibro-carti- lages of the tendinous sheaths and of the circumference of the articular cavities; 3d, into those, which adhere by their two surfaces to the bones to which they serve as a bond of union. Situation, conformation, and arrangement. — 1. The inter-articular fibro-cartilages, are situated in the articula- tions of the knee, the inferior maxillae, and the clavicle. They are lamelliform, free on their surfaces, connected by their borders to the synovial capsules or the articular car- tilages, and sufficiently moveable to adapt themselves to the motions of the joints in which they are placed; 2, The fibro- cartilages, adhering by one of their surfaces, consist, 1st, of those of the tendinous sheaths, which facilitate the glid- ing of the tendons, and protect them from the impression of the bones; and 2d, of those which surround the glenoid and cotyloid cavities; 3, The fibro-cartilages which are ad- herent by their two faces, are placed between the surfaces of the bones, to which they serve as bonds of union: these vary in form, being circular in those which connect the bodies of the vertebrae, almost quadrilateral between the symphysis pubis, &c. Structure. — The fibrous and cartilaginous tissues are not combined in the same proportion, nor disposed in the same manner in every part of the fibro-cartilaginous sys- tem, nor every where in the same fibro-cartilage. Thus, the fibrous substance predominates in the inter-vertebral ligaments, where it forms concentric layers; it is less abun- dant, and consists of circular fibres where it surrounds the are regarded by Meckel, Beclard and other anatomists, as true cartilages. We shall see in the following chapter, that this manner of observing the membranif'orm cartilages is preferable to that of Bichat. OP THE FIBROUS SYSTEM. 101 glenoid and cotyloid cavities; still less abundant in the in- ter-articular fibro cartilages, and often scarcely distinguish- able in the sheaths of the tendons, where it is formed at the expense of the periosteum, which is almost entirely converted into cartilage. In general, the fibrous substance is more apparent in proportion as the fibro-cartilage is ex- amined near its external surface; and the cartilaginous, in proportion as we approach nearer to the centre of an organ where the fibres disappear. In some instances there is alternately a layer of the fibrous tissue and one of the car- tilaginous. The fibro-cartilaginous system, like the two of which it is composed, has but little vascularity. Characters, physical and chemical properties. — The fibro-cartilages are of a whitish appearance, and unite to the tenacity of the fibrous system, the elasticity of the car- tilages. It has been observed, that during pregnancy, the fibro-cartilages which unite the bones of the pelvis are sen- sibly softened, and become more humid. The fibro-carti- lages resist, for a considerable time, the action of boiling water, but dissolve at last into gelatine. Vital properties. — In the healthy state, the fibro-carti- lages appear to have neither sensibility nor contractility. Differences according to age. — In infancy, the fibro-car- tilages are soft, and appear to be composed principally of ahomogeneous substance, and as their consistency increases, their fibres become distinct, and more fully developed. They seldom ossify in old age. Functions. — The fibro-cartilaginous organs differ in their uses in the different parts of the body: some facilitate the motions of the tendons, giving them a point of attach- ment at once solid and elastic; others favour the mobility of the articular surfaces between which they are situated, either as a kind of cushion, or as elastic ligaments. Pathological Anatomy. In consequence of their small degree of vitality, the 102 BIBLIOGRAPHY OF the fibrous system. fibro-cartilages are seldom subject to diseases; when wounded, they inflame, and after a considerable time they cicatrize and heal. Inflammation of these organs is slowin its progress and is characterized by redness, which is either uniform or striated, and often passes to a brown colour; it often terminates in the effusion of a kind of ichorous matter, which is either deposited in their substance, or exhaled upon their external surface. They seldom ulcerate, though this has been observed to take place. In many ricketty sub- jects, and in some of those who suffer from mal-conforma- tion of the vertebral column, the inter-vertebral fibro-car- tilages tumify, and become softened and engorged with fluids. Amongst the preternatural fibro-cartilaginous pro- ductions, we may cite those which are developed in the fibrous tissue in consequence of accidental friction, and those which occur in some cysts, or in certain tumours, and cicatrices, as in tubercles of the lungs, and in many other fibrous bodies. Bibliography of the fibrous System, Besides the works already cited, the reader is referred particularly to the excellent articles by Beclard in his ad- ditions to the Anatomie Generale de Bichat, and to those in his own work, Chap. VII. (vas. sys.) p. 328, et seq. For an account of the pathological anatomy of the fibrous and fibro-cartilaginous systems, see l'Histoire Anatomique des Inflammations de M. le docteur Gendrin, p. 322, et seq., and the articles by Laennec, in Dictionnaire des Sciences Medicales; tome XV. CARTILAGINOUS SYSTEM. 103 CHAPTER V. CARTILAGINOUS SYSTEM, SECTION 1. General Observations. Definition. — The cartilages, or the organs which com- pose this system, consist of hard whitish substances, some- what flexible and elastic, having apparently neither texture nor organization, independent of each other, and generally in connexion with the osseous system. Division. — The cartilages are divided into two great classes; into those which are temporary and those which are permanent. These last are again subdivided into two classes; the first comprehends the articular cartilages, or those which are not covered by the perichondrium; in the second are included all those which receive a covering from this membrane, viz. the membraniform cartilages, the cartilages of the ribs, the larynx, &c. Conformation and relations. — The cartilaginous or- gans present a great variety of form; some are long and narrow, others thin and broad and spread out like a kind of membrane; all are more or less flattened. We shall enter more into detail with regard to their form in the following sections. The articular cartilages are firmly united to the articular extremity of the bones, either by their two sur- faces, as in the synarthrodial joints, or by one only, as in the moveable articulations. Those of the second subdivi- * 104 CARTILAGINOUS SYSTEM. sion adhere to the bones, as those of the ribs, the ear, the nose, &c. or they are in relation with the soft parts, as those of the larynx, &c. Texture. — At first sight, the cartilaginous tissue appears to be composed of a homogeneous substance, but upon a more minute examination, small fibres may be discovered, whose direction varies in the two subdivisions of the per- manent cartilages, as we shall see when treating of each of them separately. When macerated for a long time in water, this tissue exhibits the appearance of a cellular net- work: no nerves can be traced into it; nor does it appear to have any blood-vessels, unless we consider as such the reddish or striated appearance which it sometimes ex- hibits. The cartilages are, nevertheless, penetrated by the fluids of the system; this fact, which the nutrition of these organs supposes, is rendered evident by the yellow colour with which they are tinged in some cases of jaundice. Characters, physical and chemical properties. — The cartilages are of a pearly white colour, very elastic and smooth, and when divided into thin layers, they present the semi-transparency of horn; they are divisible by the scalpel, and are the only substances which are exceeded by the bones in hardness and density. 1 The cartilages may be greatly distended without rupture of their tissue; they con- tain a great quantity of water; when dried, they assume a transparent, yellowish colour; but upon exposing them to water for a short time, they recover their former aspect: a long time is required for their maceration, and when ex- posed to putrefaction, they yield to its action less readily than many other animal substances. When boiled, they become brittle and indented, and the articular ones are alone dissolved and converted into a kind of gelatine; while the others remain insoluble and afford no gela- tine. Chemical analysis has hitherto afforded us no posi- tive data with regard to the composition of the cartilages of the human subject. According to the experiments of A CARTILAGINOUS SYSTEM. 105 Hatchett and Davy, they are composed of albumen and phosphate of lime, and according to Mr. Allen, of albumen and a small proportion of carbonate of lime. Mr. Gendrin regards the gelatinous substance, obtained by boiling arti- cular cartilages, as a compound of albumen, animal mucus and phosphate of lime; according to this author, the carti- lages of the larynx contain gelatine, formed in great mea- sure of fibrin in combination with water. Vital properties. — The cartilages have little sensibility in their healthy state, and their vital action is very ob- scure: they are slowly developed, except at the period of puberty, when those of the larynx suddenly increase, and form one of the most remarkable characteristics of that age. Differences according to age. — The cartilages have at first the appearance and consistence of thick mucilage; but they gradually increase in density, until they at length ac- quire their proper degree of solidity. In adult life, they are more elastic than at any other period; in old age, they become more dry, increase in colour and opacity; and sometimes, in consequence of the greater proportion of calcareous substance, they become hard and ossified either in part, or entirely. The cartilages of the diarthrodial joints are the only ones which are not subject to this trans- formation, which sometimes affects the others at a very early age. Functions. — The use of the cartilages is to facilitate the motions of the bones, to connect them together, and to form the basis of certain parts, either in part or entirely. Pathological Jinatomy. When the cartilages are divided without loss of sub- stance, the surfaces of the solution of continuity remain in juxta-position, but do not contract adhesions, and the peri- chondrium alone, when it exists, cicatrizes and forms an osseous callus which closes up the wound. When detached from the surrounding tissues, they do not unite with them. 15 106 CARTILAGINOUS SYSTEM. Inflammation of these organs, though not well characteriz- ed, sometimes terminates in ulceration, tumefaction, and softening, and the development of lardaceous productions, especially in some of the diseases of the joints. We shall speak more in detail concerning these alterations, when treating of the different kinds of cartilages. In some instances, cartilages are accidentally developed in the animal economy: Mr. Laennec has divided them into perfect and imperfect — a division which has been re- jected by Meckel, who made his observations at different periods of the development of similar productions. The accidental cartilages occur under the form of layers in the thickness of the parietes of the arteries, the subserous tis- sue of the spleen, the lungs, the testicles, &c. ; in irregular masses in the substance of some organs, as the thyroid glands, the ovaries, &c, and finally, in some schirrous and lardaceous tumours under the form of small, flattened bodies, which are either attached or free on the exterior or in the interior of the synovial membranes, but seldom in the se- rous. The ureters, the vagina, and the prepuce, are all sometimes the seat of a cartilaginous transformation; and sometimes, though very seldom, even the bones them- selves. section 2. Articular Cartilages. Definition. — The articular cartilages are those which cover the articular surfaces of the bones. Division. — The articular cartilages are divided into the diarthrodial and synarthrodia!, or into those of the movea- ble and immoveable articulations. Conformation and arrangement. — {a) The diarthro- dial cartilages are in the form of flattened lamellae, which are more thin at the circumference than at the centre CARTILAGINOUS SYSTEM. 107 of the convex articular surfaces; more thick, on the contra- ry, at their borders than at their centre on the concave ar- ticular extremities, spread upon the osseous diarthrodial surfaces, which they cover in every part of their extent, and to which they are firmly united by one of their sur- faces, while the other is lined by the synovial capsule which separates it from the corresponding surface of the opposite articular cartilage, (b) In the immoveable joints, the articular cartilages are lamelliform, and adhere to the bones by their two surfaces, and to the periosteum by their borders. * Texture. — By long maceration, the action of ebullition, &c. , it can be satisfactorily shown that the tissue of the articular cartilages is of a homogeneous nature, and com- posed of fibres. These fibres are small, and are disposed perpendicularly on the osseous surface which they cover, and to which they are very intimately united; those of the diarthrodial cartilages appear to become soft at their free extremity, where the cellular tissue which enters into their composition is modified, so as to perform the office of the synovial capsule which lines the cartilage. The blood- vessels, nerves, and lymphatic vessels of the articular car- tilages are so small as to elude observation, but there can be no doubt of their existence, as is clearly shown by the phenomena of disease. Chemical characters. — The articular cartilages are the only ones that can be reduced into gelatine by the action of ebullition. Differences according to age. — To what we have al- ready said upon this subject in the preceding section, we may add that the diarthrodial cartilages become very sen- sibly thinner in old age, and that they ossify less readily * The synarthrodial cartilages of the bones of the cranium are more thick on its convex surface than on its concave; so that the sutures are less distinguishable on the interior than on the exterior of that osseous vault. 108 CARTILAGINOUS SYSTEM, and more seldom than any other; and that, on the contrary , those of the immoveable articulations belong; rather to the class of temporary cartilages than to that of permanent. Functions. — The articular cartilages counteract, by vir- tue of their elasticity, the efforts of compression and the shocks which are experienced by the articular surfaces; they facilitate, also, by virtue of the same property, the motions of the diarthrodial joints. Pathological Anatomy. In the phlegmasia? of the joints, the articular cartilages are sometimes swollen and softened, so that their fibres be- come apparent on their interior as well as on their free sur- face, which assumes a velvety appearance. These cartilages, especially those of the diarthrodial articulations, are seldom subject to inflammation; sometimes, however, it takes place, and terminates in suppuration, in ulceration, and the destruction of the cartilage.* In some instances, the articular cartilages are replaced by a hard, ivory substance, which, according to Meckel, consists of the urate of soda. It sometimes happens that the diarthrodial cartilages be- come thinner than natural — a phenomenon which Mr.Laen- nec has attributed to the incomplete reproduction of a part of a cartilage that has been destroyed by ulceration. The cartilaginous or osseous incrustations which are sometimes found in the articular cartilages, are new productions which enter the joint by traversing the synovial membrane, and are lodged in depressions of the cartilaginous layer. In the false articulations which are found between the two fragments of a broken bone, there is generally a tissue which is more or less analogous to that of the diarthrodial cartilages, but which ought to be considered merely as an imperfect callus. * This destruction is followed by the union of the denuded surfaces of the bones which are then brought in contact, and constitute tnu anchy- losis. (V. Path. Anat. of the Oss. Sys. p. 167.) CARTILAGINOUS SYSTEM. 109 SECTION. 3. Perichondroidal Cartilages. Definition. — The perichondroidal cartilages are those which constitute the basis of certain organs, either in part or in whole; are covered by the perichondrium, and may be reduced into gelatine by the action of ebullition. These cartilages, are those of the ribs, the larynx, the auricular canal, the septum nasi; and those of the alas nasi, the eye- lids, the pavilion of the ear, the tongue, the epiglottis, the trachea and bronchia, which Bichat has improperly ar- ranged under the head of fibro-cartilages. Form and connexions . — The perichondroidal cartilages vary in form; some, as the thyroid, &c, are membraniform; others, as those of the ribs, are in the form of thick nar- row bands; while others again, as those of the trachea and bronchia, represent incomplete rings. In some instances they adhere to the bones by their borders, or their extremi- ties are intimately united to them like the articular car- tilages, as the cartilages of the ribs, the septum nasi, &c, while others are in relation only with the soft parts, as those of the eye-lids, the larynx, and the trachea. Some of these cartilages, as those of the larynx, form true articula- tions, and are united together by ligamentous capsules. — • For a more minute account of the form and connexions of these organs, the reader must consult the works on de- scriptive anatomy. Texture. — (a) The costal cartilages consist of elliptical plates, united together by transverse fibres: according to Herissant, they have a spiral arrangement. Whatever it maybe, it is certain that they can be decomposed into fibres, and reduced finally to cellular tissue; but to analyze the tex- ture of these cartilages, it is necessary to macerate them for a long time in water, followed by their desiccation or 110 CARTILAGINOUS SYSTEM. the action of the acids. By maceration and ebullition, the other cartilages of this class may at first be reduced to short and very delicate fibres, and afterwards to cellular tissue. Those of the eye-lids, of the ear, and all the membraniform fibro-cartilages of Bichat are less dense, and offer less re- sistance to maceration, &c, than the other cartilages. They are covered by a thick perichondrium, which sends fibrous elongations into the interior of their substance, while the fibrous envelope of the preceding cartilages is united to them merely by cellular tissue. Physical properties. — The perichondro'i'dal cartilages, especially the membraniform, are more or less flexible, and very elastic; they contain more earthy matter than the diar- throdial, and can not be resolved into gelatine by the ac- tion of boiling. Differences according to age. — Some of the perichon- dro'i'dal cartilages, and especially those of the ribs, the larynx and the trachea, after they are fully developed, be- come hard, and ossified either in part, or in whole, and ac- quire a soft and spongy texture in their centre. In the cos- tal cartilages, this normal transformation is accelerated by phthisis pulmonalis, and in the larygeal, by phthisis laryn- gitis. Functions. — The cartilages, of which we are treating, constitute, either alone or in conjunction with the bones, the basis of certain parts of the body, determine their form, and perform the offices of bones wherever the movements of dilatation and contraction, &c, require an elastic and more or less flexible structure. Pathological ,/lnatomy. The form of the perichondro'i'dal cartilages is sometimes altered by the action of mechanical agents; thus tumours of the neck, such as goitre, &c, give the tracheal and bronchial arches a flattened or triangular form by the com- pression which they exert upon them. CARTILAGINOUS SYSTEM. Ill The solutions of continuity of these cartilages are not followed by their cicatrization; but the perichondrium forms a cartilaginous or osseous ring, which surrounds the fragments and maintains them in contact. This ring is smaller in proportion as the corresponding extremities of the fragments are maintained in apposition. If ossification of the cartilage has already taken place, it forms a true cal- lus between the fractured extremities. (V. Path. Anat. of the Oss. Syst.)— Inflammation of these cartilages ordinarily terminates in ossification. The cases of caries and necrosis that occur in the cartila- ginous organs, particularly in the larynx, affect only those parts which are subject to osseous transformations. Amongst the small number of congenital anomalies that have hitherto been observed in these cartilages, we may notice the absence of some of them, and particularly those of the ribs. Bibliography of the Cartilaginous System. Besides the works already cited: Hirissant. Sur la structure des cartilages des cotes de Phomme et du cheval; dans Mem. de Paris, 1748, page 355. Delassone. Sur l'organization des os; dans Mem. de Paris, 1752, page 253 — 258.— In this memoir are contained some very interesting details on the texture of the ar- ticular cartilages. J. G. Haase. De fabrica cartiligium, Leipsig, 1767. Doerner. De gravioribus quibusdam cartiliginum muta- tionibus, Tubing. 1798. Cruveilhier. Observations sur les cartilages diarthrodiaux et les maladies des articulations diarthrodiales; dans Jirch. ghiir. de. Med., fevr. 1814, pag. 161. Gendrin. Hist anatom. des inflammations, torn. I, pag. 322 et seq. 112 OF THE OSSEOUS SYSTEM. CHAPTER VI. OF THE OSSEOUS SYSTEM. SECTION 1. OF THE BONES. ARTICLE I. General Observations. Definition. — The osseous system is composed of an as- semblage of hard organic pieces, which are united together in various ways and in such a manner as to form a kind of frame, which serves as the basis upon which the whole fabric is built; determines the general configuration of the body, the motions of its several members, and regulates its attitudes. Situation. — The bones are always situated in the cen- tre of the soft parts, under the teguments and the muscles that cover them. Division. — Accordingly as one or two of their dimensions predominate, or as all three are nearly equal, the bones are divided into long, broad and short: when they have the dimensions of any two of the preceding kinds, they are called mixed. These varieties differ not only with regard to their dimensions, but also in some other characters, as we shall see when speaking of each in particular. Conformation. — As the osseous system presents in its whole the general configuration of the body, it is evident that that of the individual bones themselves presents many OF THE OSSEOUS SYSTEM. 113 varieties in the different regions in which they are situa- ted — a fact which indicates the division which we have just established: we shall revert to this subject in the history of the different kinds of bone; while we speak here of the protuberances and depressions which are presented on the surfaces of all the bones, and which modify their confor- mation. 1. Of the eminences. — The eminences are either arti- cular or non-articular: the first are incrusted with cartilage, and enter into the formation of the joints; the second are destitute of cartilage, are more or less rough, and are des- tined for the most part to give insertion to muscles, &c. The varieties of form, which are presented by these emi- nences, have induced anatomists to distinguish them into several species, known under the generic names of apo- physes, processes, and rami, when they are long and very salient; by those of jjrotuberances and tuberosities, when they are short, rough and unequal; by those of crests, when they are very salient, narrow, and extended; of spines, when they are small, thin and acute; of lines, when they are long and slightly projecting. 2. Of the depressions. — The depressions, or cavities, are also distinguished into articular and non-articular: the first only, like the corresponding eminences, are incrusted with cartilage. (See History of the Articul.) The second, which will alone occupy our attention on the present occa- sion, are either external or internal. The external cavi- ties are generally mere depressions, but sometimes they constitute true cavities: both present many varieties of form; thus, when the depressions have a large and wide cavity, they are termed fossae, or digital impressions. When the cavities are deeper, narrow at their origin, and wide in the rest of their extent, they are termed cells or sinuses, according to their number and capacit}', which are in an inverse ratio; the former being predominant in the cells; the latter in the sinuses: they are lined by a mu- 16 114 OF THE OSSEOUS SYSTEM. cous membrane, and contain atmospheric air. The third class comprehends, under the names of furrows, grooves, &c, the depressions which are more or less narrow and elongated, and which generally receive blood-vessels and nerves; in the fourth class are included the foramina, fis- sures and canals, which pierce through the substance of the bones, and are more especially destined to give passage to vessels and nerves. The osseous eminences and cavities are formed either by a single bone, or, as is most frequently the case, by the union of two or more of these organs. Many of the bones, also, present rough, uneven surfaces, which serve for the attachment of muscles, ligaments, &c. Besides the cavities which communicate on the exterior of the bones, there are some which are completely internal, and which modify in a considerable degree, the interior conformation of these organs. On the internal surface there are small cavities which are single, and in the form of ca- nals in the bodies of the long bones, and under the form of cells, varying in number, size and figure, in all the other parts of the osseous system. These cavities, which result immediately from the texture of these organs, are always more developed in the centre of the bones than at their extremities: they sustain the marrow and prevent one part of it from compressing another. Texture. — The bones are composed of a nbro-lamellated tissue, very compact at their exterior, more spongy at their interior; this difference of texture has induced anato- mists to distinguish in them a compact, a reticular, and spongy tissue. In the first, which serves always as a co- vering to the others, the fibres and lamellae are applied upon each other in such a manner as to give the bone a fibrous appearance. The fibres being very irregular, and in juxta-position, leave mere microscopic interstices be- tween them of the form of small canals, being composed of lamellated layers, united together by transverse or ob- OF THE OSSEOUS SYSTEM. 115 lique fibrillae. The reticular tissue is less compact and con- stitutes the most internal layers of the bone. In the spongy tissue, the fibres and lamellae leave small spaces or cells between them, which resemble those of sponge or of inflated cellular tissue, and form the second kind of the small osse- ous cavities to which we have just alluded. Modern re- searches have ascertained that the osseous texture is nothing but cellular tissue, hardened by its combination with a ge- latine- calcareous substance, but which preserves the inte- rior form of its primitive state until the fat is deposited into its cells. Besides the osseous tissue, there are other parts that en- ter into the composition of bones, and these are: 1st, a fi- brous membrane which serves as an external envelope, and which has already been described under the name of peri- osteum (v. page 94); 2d, the marrow, or the adipose tis- sue of the bones, which is lodged in the cells of the spongy and reticular substance, and even in the compact tissue, as well as in the large interior canal, of the long bones, where it is contained in a cellulo-vascular membrane peculiar to that canal. The fat of bones consists, if not every where, at least in the most spacious lacunas, of small spheroids fill- ed with an oily substance, more fluid and of a more yel- lowish colour than that of the general adipose tissue; 3d, blood-vessels, which have been distinguished by anatomists into three orders: the first comprehends the small arterial branches, which are derived from the vascular net-work of the periosteum, and which enter the microscopic orifices, and are distributed to the compact substance. The second order consists of the vessels which penetrate into the spongy substance by the foramina, which are observable upon the surfaces of the short and at the extremities of the long bones: in the third order are included the vessels known more particularly under the name of nutritient, which tra- verse, without ramifying, the hollow canals in the compact substance, and are distributed to the membrana medullaris. 116 OF THE OSSEOUS SYSTEM. The corresponding veins of the first two orders do not pass out at the orifices which receive the arteries, while the ar- teries of the third order are generally accompanied by veins which exactly correspond to them in number and volume. The parietes of the veins of the compact and spongy tis- sues are formed merely of the internal membrane of the venous system; they present a cellular arrangement, which establishes an analogy between them and those which con- stitute the erectile tissue of the corpora cavernosa, &c, being formed, like them, merely of the internal mem- brane of the venous system — a character which belongs also to the small venous ramifications of the compact sub- stance. As yet, no lymphatic vessels have been traced into the substance of the bones; and the nerves, which accompany the vessels of the medullary membranes of the long bones, can not be discovered in the osseous tissue itself. Characters, physical and chemical properties. — The bones are of a white, yellowish colour, very hard, compact and resisting, possessed of a very small degree of flexibili- ty and elasticity, and susceptible of slow extension, follow- ed, when the cause of extension is removed, by the return of these organs to their primitive dimensions; (as in some of the osseous cavities, such as the nasal fossae, the orbit, &c. which are sometimes temporally enlarged by the pre- sence of tumours, and which regain their original capacity as soon as these tumours are removed). The solidity of the bones depends upon their chemical composition, which, according to the analysis of Berzelius, consists of the fol- lowing ingredients: — Animal substance reducible into ge- latine, 32.17; insoluble animal substance, 1.13; carbonate of lime, 1 1.3; phosphate of lime, 51.4; fluate of lime, 2.00; phosphate of magnesia, 1.16; soda, and phosphate of soda, 1.20. The analysis of Fourcroy and Vauquelin differs somewhat from the preceding; for, besides the ingredients already enumerated, these chemists have detected the pre- OF THE OSSEOUS SYSTEM. 117 sence of a small quantity of iron and silica. The composi- tion of the bones varies also according to the age of the individual, the state of health or disease, and the kind of bone that is examined. The gelatinous parts of bone are extracted slowly by boiling water, and the saline part is readily decomposed by some of the acids. Vital properties. — The bones, in their healthy state, possess but a small share of sensibility; they are destitute of contractility, and the slowness with which they are formed and repaired, sufficiently proves that they are en- dowed with but a small degree of vitality. Mode of development, and differences according to age. — The bones, which are at first liquid like all the other parts of the body, become gradually gelatinous, and pass suc- cessively (at least the majority of them,) into the cartilagin- ous and fibro-cartilaginous states, and from these into the osseous. At the commencement of embryotic life, the os- seous system is merely of the consistence of mucus, and forms an uninterrupted whole, which is soon after divided into a great number of parts. Ossification begins about a month after the time of conception, and is not fully com- pleted before the twelfth, and in some accessory parts, not until the eighteenth year of age. Ossification does not appear to result uniformly from the change of cartilage into bone. According to Howship, some parts of the os- seous system, such as the bodies of the long bones and the broad bones of the cranium, pass immediately from the mucous to the osseous state. The formation of bone is accompanied by some very remarkable and curious pheno- mena: in the centre of the temporary cartilage, which is formed about two months after conception, and which has already the configuration of the bone, may be observ- ed small canals, and vessels which are lined by a vascular membrane, filled at first with a viscous, and subsequently with a sanguineous fluid: the appearance of this fluid is IIS OF THE OSSEOUS SYSTEM. soon followed by that of the first osseous point.* The car- tilage, being injected with red around the transformed part, presents a homogeneous aspect in proportion as it is examined near its circumference. Ossification thus ex- tends gradually from within outwards, and finally termi- nates by the complete removal of the cartilage. The canals to which we have just alluded, being large at the com- mencement of ossification, diminish progressively, and in proportion as the process of ossification is completed: and instead of the homogeneous substance of the temporary cartilage, there is a complete bone, having distinct fibres and blood-vessels. Though numerous hypotheses have been advanced in explanation of the conversion of the cartilaginous into the osseous tissue, our information of the nature of this nutri- tive phenomenon is still involved in doubt and uncertainty like that of every other part of the animal economy; and all the knowledge we possess upon this subject is, that the formation of bone results from a change of nutrition of the cellular net-work, in consequence of the afflux of blood to the cartilage, and by virtue of which, the albuminous, ho- mogeneous substance is converted into a lamellated tissue, composed of gelatino-calcareous fibres. In many of the bones, ossification takes place in several points; thus, in some instances, the two symmetrical halves of the azygos bones are developed separately, coalesce from the opposite sides, and are confounded with each other on the mesian line, as in the frontal and inferior • Every normal or accidental ossification is preceded by the develop- ment of a small, red, vascular apparatus, in the point of the cartilage or fibro-cartilage which is about to be changed into bone. From the moment that ossification takes place (always in the centre of this appa- ratus,) the formation of vessels, or at least their development and colo- ration, continue to increase, and in such a manner that the ossified part is always separated from the surrounding parts by another portion in- jected with red. OF THE OSSEOUS SYSTEM. 119 maxillary bones; while, in some of the other symmetrical bones, as in the sphenoid, the vertebras, &c, ossification commences by lateral and mesian points. The symmetri- cal bones differ from each other, both with regard to their number, and the respective arrangement of their primitive osseous points. The trace of union of some parts of the same bone, originally distinct, sometimes remains during the whole period of life, as in the bones of the sacrum. Many of the articular and non-articular eminences are form- ed by distinct points of ossification, which appear at very different periods, from the fifteenth day after birth to the fifteenth and sixteenth year of age. These osseous points are termed epiphyses, and are separated from the bone, by cartilage: when this cartilage is converted into bone, the epiphyses are changed into apophyses. We shall endeavour to express, in a general manner, the order in which ossifi- cation takes place in the different bones of the skeleton, though these rules do not always obtain. The two fo 1-1 ow- ing are those which present the least exceptions; 1st, in the human subject, the bones are developed by degrees, and run through the same stages of organization as may be observed in the animal scale; 2d, The long bones are form- ed before the flat, and these before the short* * The following being" the order in which the different parts of the skele- ton ossify, we shall perceive how difficult it is, after having- read these details, to establish general rules with regard to this point. Ossification begins at the end of the first month in the clavicle, and successively in the inferior maxilla, femur, tibia, humerus, inferior maxilla, and in the bones of the fore-arm, where it commences about the thirty- fifth day. Ossification begins about the fortieth day in the fibula, scapu- la, palate, and subsequently in the central portions of the occipital and frontal bones, the arches of the first vertebrae, the ribs, the great wing of the sphenoid bone, the zygomatic apophysis, the phalanges of the fingers, the bodies of the middle vertebrae, the nasal and zygomatic bones, the ilium, metacarpal bones; the phalanges of the toes, the occipital condyles,. and theninits basilar portion, the squamous part of the temporal; the pa- 120 OP THE OSSEOUS SYSTEM. The formation of bone then takes place, as we have al- ready said, from within outwards, by the deposition of new osseous substance around the primitive nucleus: besides, the periosteum being more vascular at the period of ossifica- tion than at any other time, secretes and deposits upon its internal surface, osseous layers, which are united to the bone and add to its thickness.'* It is then by a kind of juxta- rietal and the vomer: in all these bones ossification commences about the middle of the seventh week. In the course of the same week, it begins in the orbitar process of the sphenoid, and finally, in the metatarsal bones and phalanges of the toes, and in the last joints of the fingers. During the ten succeeding days, ossification commences in the body of the sphe- noid, in those of the first sacral vertebra:, and in the circle of the tym- panum. About two months and a half after conception, it is manifested in the costiform appendix of the seventh vertebra; before the end of the third month, in the labyrinth, and about the end of the third month in the ischium, and internal pterygoid apophysis; about the middle of the fourth month, in the small bones of the tympanum; at half .the term of uterine life in the pubis, os calcis, the last joints of the toes, in the lateral portions of the ethmoid, and in the spongy bones of the nose; and somewhat later in the first pieces of the sternum; about the sixth month, the body and processus dentatus of the second cervical verte- bra, and the anterior and internal masses of the pelvic or sacral verte- bra, and subsequently, the astragalus begin to ossify. About the sev- enth month, the ethmoidal pyramids ossify; then the crista galli; and at the period of birth, the first coccygeal vertebra, the os cuboides and the anterior arch of the altas. About the twelfth month, the coracoid process, os magnum and unciforme of the carpus are solid; about the third year, the first cuneiform bone, the patella and the triquetral bones are ossified; at the fourth year, the second and third cuneiform; about the fifth, the scaphoid of the tarsus, the trapezium and lunare; at eight, the scaphoid of the carpus ossifies; at nine, the trapezoides, and finally the pisiforme, about the twelfth year of age. Beclard, Anat. Generale, p. 496. * The depressions and cavities of the bones are determined at the mo- ment of ossification, either by the presence of some organ upon which the bone is modelled, or by active pressure, which is opposed to the de- velopment of the parts, where ossification takes place; there being no \ OF THE OSSEOUS SYSTEM. 121 position that the first development of the bones is effect- ed; but, when once formed, they increase by an interstitial nutrition, which becomes gradually less active, until at a certain age, (about the time when all the epiphyses are completely ossified and are united to their respective bones,) it is no more than sufficient to nourish the bone and keep up its preservation.* In the adult, the nutritive process continues to become more slow; the number and volume of the vessels diminish, and the bones, beingless pervaded with blood, become more dry and calcareous, lose their elasticity, and diminish in thickness; hence the remarkable enlargement of their interior cavities and their brittleness in old age. In the female, the bones retain a much longer hollows in the osseous tissue as we might be led at first sight to suppose; the bones of the cranium are moulded upon the brain, the articular sur- faces upon the eminences whicli receive them, &c. &c. * The knowledge of the property of madder in colouring the bones of animals that have been fed with it for a long time, has led several learn- ed physiologists to experiment with this plant, with the view to deter- mine the mode of nutrition and growth of the bones. As those of Du Hamel are the most interesting, we shall sum up his principal results. The bones of young animals that have been fed with madder, soon be- come red, while those of old animals, on the contrary, scarcely undergo any sensible change, even after protracted feeding. If a young animal be fed with madder for some time, and then on ordinary food, the bones become red and white in alternate layers, which indicates a juxta-position, and not an interstitial nutrition. This does, probably, not take place after the epiphyses are fully united to the bones. Du Hamel does not, however, admit this juxta-position, but is of opinion, that the bones in- crease in length and breadth, merely by extension. To refute this theory, J. Hunter performed the following experiment: having perforated the two extremities of the body of one of the long bones of a young animal, it was killed some time after, and upon examination it was found that the distance which separated the two foramina, was the same as at the time of the operation. From the results, therefore, of this experiment, which was several times repeated, Mr. Hunter concluded that the bones are not subject to elongation. 17 122 OF THE OSSEOUS SYSTEM. time than in man, the characters which they possessed in youth. Functions. — The bones form an essential part of the or- gans of locomotion, performing the office of levers for the action of the muscles and their tendons, which arise and are inserted into them; they also protect from external in- jury the brain, heart, lungs, and other organs on which life more immediately depends; as well as the larger and more important blood-vessels and nerves. ARTICLE 2. Of the long, broad, short, and mixed bones in particular. § 1. Of the long Bones. Definition. — B}- the long bones we understand those elongated, osseous pieces, which contain a medullary canal.* They comprehend the humerus, the ulna, and radius; the femur, the tibia and peroneus; the metacarpal and metatar- sal bones, and the phalanges of the fingers and the toes. Situation. — All the long bones are situated in the ex- tremities, which they occupy throughout their whole ex- tent, with the exception of the carpus and the tarsus. Conformation and arrangement. — Thick and volumi- nous at their extremities, where we observe apophyses of insertion, eminences and articular cavities, the bones gra- dually diminish and form imperfect cylinders: this inter- mediate part to the extremities is termed their body or dia- physis. On the body of the bone are ridges for the attach- ment of muscles, generally three in number, directed ob- liquely, and in such a manner as to give the bone a twisted * It is from this character alone that we ought to draw the generic name of the bones of which we are treating; the other denomination be- ing too general and equally applicable to the bones without a medullary canal, as for instance, those of the ribs. OF THE OSSEOUS SYSTEM. 123 appearance. The long bones of each extremity, taken as a whole, represent a broken column, whose pieces, being ar- ticulated in various ways, as we shall hereafter see, dimin- ish in volume, and increase in number in proportion as they recede from the trunk. Structure. — There is a great difference with regard to their interior form, between the body and the extremities of the long bones. The first is composed of compact sub- stance, which is somewhat rarefied, and becomes reticular towards the centre of the bone; hence there is a canal which is lined by a cellulo-vascular membrane, which sends numerous prolongations into its interior, supported in some instances by others that are derived from the os- seous substance, and forming, by their mutual interlace- ment, a great number of cells, which are destined to receive the adipose vesicles which are deposited in their interior, or the marrow properly so called.* The medullary mem- brane appears to result from a net-work of the blood-ves- sels, lymphatics and nerves, which are derived from the ramifications of those which enter the canal through the nutritient foramina; and are strengthened and defended from injury by cellular tissue. This membrane is com- monly considered as the internal periosteum of the long bones: the quantity and consistence of the fat which it con- tains are in relative proportion to the exterior state of the individual: it is small in quantity, and almost entirely aqueous in emaciated persons, while in those who enjoy an ordinary degree of embonpoint, its proportion is more considerable. Towards the extremities of the bone, the compact substance greatly diminishes, and is finally reduced- to a mere plate which covers the spongy substance of which the extremities are composed. The medullary canal is not continued into the extremities; and, although there is some- • In birds, the medullary canal is filled v/ith air which comes directly from the lung's. 124 OF THE OSSEOUS SYSTEM. times a small quantity of marrow in the cells of the spongy substance, there is never any distinct membrane. Characters and physical properties. — The long bones unite to the physical characters, which they possess in com- mon with the rest of the osseous system, the property of resisting, in a very great degree, such forces as have a ten- dency to break them, by virtue of the compact texture of their bodies, and of the medullary canal which occupies their centre: indeed, in consequence of this arrangement, the bones have a greater diameter, without increase of sub- stance, and consequently of weight. Vital properties. — The osseous part of the long bones affords nothing peculiar with regard to its vitality; but the medullary membrane which lines their interior canal is endowed with true sensibility: for when this membrane is irritated after the bone has been divided, the animal im- mediately evinces symptoms of pain. It is also endowed with a small share of contractility, analogous to that of the cellular tissue. Mode of development and differences according to age. — The long bones are developed by three points of os- sification; one for the body and two for the extremities. The former appears before the other two, about two months after conception, without passing to the cartilaginous state; there being already a hollow which is occupied by the principal nutritient artery. The temporary cartilages hav- ing already the form of the extremities of the bone, are united to the ends of this cylinder, and at the period of birth, ossification begins in the centre of these terminal parts; from this mode of ossification result the epiphyses which, as we have already seen, remain several years se- parated from the body of the bone by means of cartilage. The bones gradually increase in length by the addition of new osseous substance to the extremities of the diaphysis, and by the union of this with the epiphyses. The medul- lary canal, which is at first nothing but a mere narrow ca- OF THE OSSEOUS SYSTEM. 125 nal filled by the nutritient artery, gradually enlarges, and becomes filled with a soft viscid substance; as the canal in- creases in size, the cellulo-vascular membrane becomes apparent, which, in the foetus and new-born infant, contains nothing but a very aqueous fluid, which by degrees acquires the properties of marrow. The medullary canal continues to enlarge with the age of the individual, Without encroaching upon the parieles of the bones, which themselves increase on their external sur- face; but in proportion as these cease to grow, their parietes become progressively thinner; so that in old age they form but a small share of the diameter of the body of the bone. In proportion also as the medullary canal enlarges, the quantity of marrow increases. Functions. — The long bones constitute essential parts in the articulations of the extremities, and form solid, though flexible columns, capable of being moved in various directions, by the muscles and tendons which are attached to them. § 2. Of the broad or flat Bones. Definition. — The class of bones which we are about to describe comprehends those pieces which vary in thick- ness, but are nearly equal in their length and breadth; as the frontal and parietal bones, the scapula and os ilium. Situation. — The broad bones form, in part, the parietes of the cranium, the thorax and pelvis. Conformation. — They are lamelliform, quadrilateral, semicircular, &c, more or less curved, or contorted in va- rious directions, so that the same side may be entirely con- vex or concave, or alternately the one and the other; while the opposite sides are concave and convex. The flat bones are thicker at their circumference than in the centre, hav- ing inequalities of different kinds, which are more promi- nent upon their articular borders than upon those which give attachment to muscles. 126 OF THE OSSEOUS SYSTEM. Structure. — The flat bones are uniformly composed of two laminae or tables of solid and compact substance: in the flat bones of the cranium the internal layer is thinner and more dense than the external, and is hence called ta- bula vitrea. In some instances these tables are in contact with each other, especially in the centre of the bone, and in others they are separated by a layer of intermediate spongy substance called the diploe. This is exceedingly vascular, having a great number of veins, and containing a small quantity of marrow without any distinct membrane. Mode of development, and differences according to age. — The broad bones are developed by two or more points of ossification, which become manifest in the mu- cous substance at the end of the second month of pregnan- cy, between the periosteum and the dura mater for the bones of the cranium, and between the two lamina? of the periosteum for the other flat bones. The osseous fibres issue in rays from the centre towards the circumference, and finally form laminae with radiated fibres, which are still separated by the mucous substance. It has been observed by Bichat, that we ought to refer the origin of the su- tures, which unite some of the flat bones with each other, to the interspaces which are left at this period between the fibres of these bones. Soon after the laminae of which the flat bones are composed, are united, their substance be- comes more conspicuous, and the tables, which were at first confounded, become more distinct in proportion as they increase in density; leaving between them, as they sepa- rate, an intermediate spongy substance formed at the ex- pense of the internal fibres of their contiguous surfaces. In old age this substance is absorbed, the two tables are again brought in contact, and the bone becomes sensibly thinner and weaker: to this circumstance ought to be at- tributed the sinking of the parietal protuberances observa- ble on the skulls of old people. Functions. — The flat bones serve to defend from exter- OF THE OSSEOUS SYSTEM- 127 nal injury the organs which are contained in the cavities which they contribute to form, and participate in the func- tions of locomotion, either by furnishing immoveable ful- cra for the action of the muscles, or in performing the mo- tions which these organs impress upon them. § 3. Of the Short Bones. Definition. — Under this class are comprehended all the bones whose length, and breadth, and thickness, are nearly of the same dimensions. Situation. — The short bones are generally collected in groups, and are situated in the hand and foot, &c, and in the vertebral column, which is formed exclusively by them. Conformation. — The short bones present too many ir- regularities to enable us to point them out in a general de- scription. Their form is generally determined by the parts around and between which they are situated: they are globular, tretroidal, cuneiform, cuboidal, &c. : all of them are furnished with eminences and depressions, either for their articulation or for the attachment of the soft parts. Structure. — The internal substance of the short bones consists of a soft, spongy, and areolar texture, which is covered and defended exteriorly by a layer of firm com- pact substance: they are supplied with blood-vessels, and contain a small quantity of marrow without any distinct membrane, like all the bones that have no medullary canal. Mode of development, and differences according to age. — The short bones ossify slowly, and pass from the mucous to the cartilaginous state; and the temporary carti- lages in which they are formed have the shape and volume of the bone long before it is completed: ossification of the short bones also takes place from the centre towards the circumference, and is attended with the same phenomena as the ossification of the other bones. Some of the short bones are developed in the thickness or in the continuity of some of the tendons or ligaments, and pass successively 128 OP THE OSSEOUS SYSTEM. from the fibrous to the fibro-cartilaginous state, and finally to the osseous. The patella and the sesamoid bones are formed in this way; so that they do not appear to be es- sential parts of the skeleton, and are considered by some as accidental bones. Functions. — Nature has placed the short bones in every place, where it is necessary to combine a great degree of solidity with that of mobility. To attain this double pur- pose, it was necessary that they should be small and ar- ranged in groups. Indeed, we know, that an instrument, formed of several pieces which are firmly united together, is more solid than one that is composed of a single piece, because such efforts as have a tendency to break it are lost at their point of union, and that the principal motion of a series of organs occupying a given extent, is also much greater in proportion as these organs are more numerous, and consequently smaller. The short bones of the verte- bral column, moreover, form a kind of bony case for the spinal marrow, which is thus defended from external in- jury. § 4. Of the Mixed Bones. Definition. — The mixed bones are those which combine the form and characters of the preceding classes, and ap- pear to result from the union of the bones of two or even three of them; as in the sphenoid, the ethmoid, the tem- poral, the occipital, the ribs and the sternum. Situation. — Most of them belong to the head and the thorax. Conformation. — Their form is very variable, and re- sults most frequently from the union of a broad, a short, and a thick part. Structure. — The mixed bones present the same struc- ture as the bones with which they are connected. It is in this class that is comprehended the hardest and most com- OF THE OSSEOUS SYSTEM. 129 pact osseous part of the skeleton, viz. the petrous portion of the temporal bone. Mode of development.— -These bones are formed by- several points of ossification, and possess in each of their respective parts the mode of development of the kind of bone with which they are connected. Functions. — The mixed bones perform different func- tions in the animal economy; they contribute to form the cranium and the thoracic cavity, surround and defend the organs which they contain, the encephalic nerves and some parts of the organs of sense, and give attachment to muscles. Pathological Anatomy. The bones are often subject to mal-formations, which are either congenital or accidental. The first are frequently observed on the vault of the cranium, less often on the pa- rietes of the thorax and abdomen, and seldom in the ex- tremities. They consist either in a defect, or in an excess of development of the osseous parts where they are found, and are most frequently accompanied by congenital ano- malies of the viscera which they surround. The mal-for- mations which are consequent upon the development of the bones, depend sometimes upon accidental hypertrophy or atrophy, as may be observed in some of the chronic dis- eases. Sometimes also they result from inflammation and swelling of the periosteum, accompanied by the secretion of osseous matter, which is deposited upon the internal surface of that membrane, and which, uniting with the bone, constitutes what is called external exostosis: this morbid development is presented either under the form of a circumscribed nodosity, and is then termed node, or under that of a tumour, varying in extent, and composed of large and superadded layers. When treating of inflammation of the bones, we shall have occassion to point out some of the IS 130 OF THE OSSEOUS SYSTEM. various alterations which it is capable of producing in the osseous system. The solutions of continuity or fractures of the bones, de- serve our particular attention in relation to their mode of healing. In the following; exposition of the different the- ories of the formation of callus (cicatrix,) that have been hitherto advanced, we shall see the great discrepancy in the opinions of some of the most learned and experienced physiologists, with regard to this highly interesting and important subject. The ancients were of opinion, that the extremities of the fragments of a broken bone secreted a kind of osseous fluid or coagulable lymph, which gradually acquired con- sistency, and glued the extremities together. Haller af- terwards extended this theory, and asserted that the fluid, exhaled by the extremities ot the fragments and the mar- row, was effused around them, and became successively mucous, then cartilaginous, and finally osseous; passing thus through all the different stages of the original ossifi- cation. According to Haller the periosteum is entirely passive in the formation of callus. By Mr. John Hunter the formation of callus is referred to the organization and ossification of the blood which is extravasated around the broken fragments. In the present day, Mr. Howship, embracing the ideas of M. Dupuytren, has added addi- tional proof to the theory of Hunter, and asserts that the periosteum becomes cartilaginous at the extremities of the fragments; that the matter of callus is deposited successively upon the surface of the bone, the circum- ference of the extremity, and in the medullary cavity; — in a word, that the fragments are firmly re-united at their exterior parts before they are cicatrized at their extremities. The theory of Du Hamel, published before the time of Haller's, tends to prove, that the periosteum and the medullary membrane, and sometimes the first only, are elongated and united to those of the opposite frag- or THE OSSEOUS SYSTEM. 131 ments, and ossified in such a manner as to surround the fracture by a kind of osseous ring. This re-union, in which, according to Du Hamel, the extremities of the fractured bone themselves did not participate, was regarded by him as definite. According to the opinions of Bordenave, Bi- chat and Rieherand, fractures, that are attended by lacera- tion of the soft parts, have their contiguous extremities re-united by the development of fleshy granulations. Not- withstanding the theories already stated, little was known with regard to the phenomena of osseous cicatrization, un- til the researches of Dupuytren, Breschet and Villerme, threw new light upon this subject, and gave us more cor- rect and satisfactory information. We shall find in the ideas of these gentlemen some of those of Du Hamel, of Haller, and of Howship. According to the new theory, there are three distinct stages for the formation of callus. In the first stage, the small quantity of blood, that escapes and is effused between the fragments at the moment the frac- ture occurs, is soon followed by the exhalation of a viscid serum; the blood gradually loses its colour, and the peri- osteum, the medullary membrane, and the divided soft parts are re-united. The second stage is characterized by inflammation and swelling, accompanied by the secretion of coagulating lymph in the thickness of the periosteum, and between it and the bone: this matter is gradually ossi- fied, as well as the medullary membrane: externally, the ossification extends to the surrounding cellular tissue, and even to the muscles. Finally, & provisional callus is form- ed, a kind of osseous incrustation on the surface of the contiguous extremities, which may be compared to the osseous rings (virole,) observable in a great number of bones, and which, in the long ones, is completed by the formation of a kind of osseous pin (eheville) in the me- dullary cavity, in consequence of the ossification of the medullary membrane. The provisional callus is nothing more than a kind of solid, retentive apparatus, which serves to maintain the fragments in contact. As soon as 132 OF THE OSSEOUS SYSTEM. this is formed, commences the third stage — that of the permanent callus. Until now the bone itself has experi- enced no sensible changes; but at this period the substance that was effused between the fragments acquires consist- ency and firmness; vessels are developed which communi- cate with those of the bone and the periosteum, and finally ossification is effected, and the two extremities are thus firmly re-united. When this consolidation is perfect, the provisional retentive apparatus is gradually absorbed, and the medullary canal is re-established. When the fragments however, can not be maintained in their natural relations, after they have been brought in contact, the medullary canal remains obliterated, and the exterior callus, instead of being merely provisional, becomes permanent. When the fragments are not properly reduced, and maintained perfectly in contact, they are re-united by a kind of fibrous cicatrix, which generally happens in fractures of the patella and cervix femoris, on account of the difficulty of pre- venting the separation of the fragments. Sometimes the extremities of the fragments are rounded, becoming firm and compact, and even incrusted with car- tilage, and covered by synovial membrane: hence the ano- malous articulations which either prevent or greatly im- pede the motions of the injured parts. It sometimes happens that the epiphyses are separated from the bones by mechanical causes, or morbid changes, such as inflammation; and in these cases re-union is effect- ed in the same manner as in fractures. In cases of com- minuted fractures, the disorganized parts are re-united by callus. Wounds of the bones, with loss of substance, are generally followed by mortification, and exfoliation of the external laminse, and subsequently, by fleshy granulations and the restoration of the exfoliated substance. '* In gene- * When the periosteum alone has been injured, and the soft parts are immediately brought in contact, re-union often takes place without pre- vious exfoliation. OF THE OSSEOUS SYSTEM. 133 ral, wounds of the bones are rapidly repaired, and show the great recuperative power of the osseous tissue. The bones are often rendered thin by the pulsations of aneurismal tu- mours, and are even sometimes perforated, especially when they are thin and soft and in contact with the tumour. After amputations, the extremity of the osseous frag- ment of the stump inflames, unites with the surrounding soft parts, and is rounded and covered with a compact osseous plate, which closes up the mouth of the medullary canal. If there be lesion of the bone or the periosteum, beyond the extremity of the fragment, slight exfoliation takes place, but the cure is afterwards effected as in ordinary cases. Primary inflammation of the bones is a very rare disease; but it is often propagated to them by the surrounding parts, and always in consequence of mechanical injuries; and un- der these circumstances it is that we can best observe in them the anatomical characters of this morbid state. When the osseous tissue inflames, it swells, becomes more spongy and rarified than in its normal state, and its vessels are highly injected with blood. These phenomena are accom- panied by the secretion of a gelatinous or red serous fluid, which is deposited into its cells; the calcareous salts are gradually absorbed, and the gelatinous substance itself is evi- dently altered; the medullary canal disappears in the neigh- bourhood of the affected part; and the membrana medul- laris, whose interior elongations are red and thickened, is filled in its interstices with a fibrous substance. Inflam- mation of the bones often terminates in mortification or necrosis: their compact portions are more especially subject to these morbid derangements, on account of their small degree of vascularity. The necrosed part is uneven and of a reddish brown colour; and sometimes, when mortification succeeds to gangrenous inflammation, the es- char is brown and spongy, and emits the smell that charac- terizes gangrene of the soft parts: most frequently the gelatinous substance of the bones disappears, and even 134 OF THE OSSEOUS SYSTEM. sometimes, the calcareous salts themselves are decomposed. The hospital gangrene also extends to the osseous tissue, and reduces it to a soft, grayish, foetid, and pultacious sub- stance. In necrosis of the long bones there are some interesting peculiarities, which are important to be understood by the surgeon, and which afford another example of the recu- parative powers of the tissue of which we have been treat- ing. When the body of one of the long bones is mortifi- ed, either in part or in whole, nature sets up her restorative efforts, and forms around it another osseous portion equal to the original, and pierced by several apertures, by tra- versing which by means of a stylet, we may perceive the dead bone, and readily distinguish it in the interior of the new, by its mobility.* The sequestrum or dead part is discharged, either by the efforts of nature, or those of sur- gery, through the apertures to which we have just alluded: after the removal of the sequestrum, the openings gradual- ly close; and the new bone, assuming the form of the origi- nal, unites with its terminal portions, and, finally exceeds it in density: — it is furnished with a medullary canal and membrane. In cases where the entire thickness of the body of the bone is necrosed, the restoration is effected by the periosteum: in some instances, the internal laminae alone are mortified, and then the reproduction consists merely in an increase of the external plates, accompanied, as in all other cases of new formation, by the phenomena which are necessary for the removal of the sequestrum: in necrosis of the flat and short bones, and in the extremities of the long ones, restoration is less frequently effected than in the bodies of the long bones. Caries, or softeningand ulceration of the bones,is another * The probe penetrates as far as the sequestrum by traversing the fis- tulous opening's, which nature has established in the soft parts, to favour its elimination. OV THE OSSEOUS SYSTEM. 135 effect of inflammation: it is characterized by a softening of the osseous tissue, accompanied by a great degree of fria- bility, and a fetid ichorous discharge; when the quantity of this fluid is small and inconsiderable, the disease is term- ed dry caries — a variety which seldom occurs but in the flat bones and in old people. This ulcerative inflammation attacks more particularly the spongy bones, so that the short bones are more liable to be affected by it, than the others. When the inflammation has continued for some time, the oseous tissue becomes swollen and assumes a lamella- ted appearance; its fibres separate, and contain in their in- terstices a thick reddish matter, of the intermediate con- sistence of indurated cellular tissue and tubercles: this mat- ter is often converted into fibro-cartilage, and finally into an osseous substance constituting a kind of exostosis, charac- terized by a simultaneousswelling and increase in the densi- ty of the bone. In the exostoses, which are derived from the bone itself, there are all the characters, that are presented in the sub-inflamed osseous tissue — facts which amply prove that these tumours are the result of phlegmasia?. It is in- deed, to inflammation that we ought to look for the cause of spina-ventosa, and of osteo-steatoma, in which the swell- ing of the organ is combined with the condensation of its tissue and the alteration of its chemical composition. The bones often experience tuberculous, schirrous and cerebri- form degenerations, &c : they are also subject to a re- markable softening, which arises from an absorption of the earthy part of the osseous system, while the animal matter remains. When this disease arises during the growth of the individual, it constitutes what is termed rickets. The bones of ricketty subjects are of a reddish appearance, spongy, and easily cut with the bistoury; and those which are naturally spongy, become more rarefied and volumi- nous than the others; as in the extremities of the long bones, whose size induces the vulgar to say that the subject is i 136 OP THE OSSEOUS SYSTEM. ricketty. This state is generally only temporary; but as they acquire their natural density and solidity, the bones retain the deviations and curvatures which the pressure of the body and the action of the muscles produced dur- ing the disease. The mollities ossium is a disease aris- ing from a softening of the bones, and is generally attended by a greater degree of absorption of the earthy salts, than in the disease called rickets: it often supervenes after the formation and growth of the bones are complete; when it is accompanied by a softening and fleshy appear- ance of the osseous tissue, it is called osteo- sarcoma. In some instances, the bones are soft and brittle, at the same time that they retain their cellular texture. All the tissues, whether normal or adventitious, are sub- ject to accidental osseous productions: in the first, they result ordinarily from the effects of old age, and are sel- dom perfectly similar to the osseous tissue. Sometimes, these productions consist in mere incrustations, having a greater quantity of calcareous matter than bone, as in the arteries; at others, they consist of a soft, friable, chalk-like substance, composed of animal matter, and earthy salts, as well as a kind of ebony-like substance, as is sometimes found to occur in the cartilages of the diarthrodial joints. Ossification of the cartilages and fibro-cartilages presents all the characters of the osseous tissue. SECTION 2. Of the Articulations of the Bones. The bones are connected together through the medium of other substances, and in such a manner as to form an en- tire whole called the skeleton, which determines the ge- neral configuration of the body, and constitutes the basis upon which the whole fabric is built. The bones are all so admirably arranged, that the extremity of every one is OP THE OSSEOUS SYSTEM. 137 perfectly adapted to the end of the bone, with which it. is connected; and this connexion is termed their articula- tion. Every articulation has its articular osseous parts and the media by which they are united. The articular surfaces, generally, present inequalities, which determine the different kinds of joints, as well as the extent of mo- tion of the moveable articulations. The long bones are ar- ticulated by their extremities, the broad ones by their bor- ders, and the short ones by different points of their surfaces. All the bones are united through the media of cartilages, fibro-cartilages, or, fibrous ligaments. In consequence of the variety of form of the articular parts; of the differences of their mode of union, and their immobility or mobility, anatomists distinguish three kinds of articulation; the first is called synarthrosis, the second amphiarthrosis, and the third diarthrosis. 1. Synarthrodial Articulation. — All the bones of the head, except the inferior maxilla, are connected by the synarthrodial articulation, and are immoveable with regard to each other. The articulatory parts present many varie- ties as regards their form and relations, but they are all united by an intermediate cartilage which adheres firmly to them, and by the periosteum which covers it in its pas- sage from one bone to the other. In old age, the synarthrodial articulation is often oblite- rated by the immediate continuity of the two bones which it connects, in consequence of the ossification of the synar- throdial cartilage. Synarthrosis is divided into several varieties: lsjt. Thetruesuture is that kind of articulation which ex- ists between the bones of the cranium, where the articular surfaces present a great number of indentations, which cor- respond to an equal number of proportionate depressions, into which they are received. Owing to the trifling dif- ferences which exist in the form of the indentations, this 19 13S OF THE OSSEOUS SYSTEM. suture has been divided into three varieties, viz., the den- tata, serrata, and limbosa. 2d. The false or harmonic suture, in which the bones arc connected together by means of rough margins; in this manner the bones of the nose are connected together. 3d. The scaly suture, when the corresponding bones overlap each other, by the separation of their borders, which are sharp and unequal, as in the temporo-pari- etal articulation. The scaly suture is said to be double or reciprocal when the bones do not correspond by the same surfaces throughout their whole extent: the spheno- frontal articulation is an example of this variety. 4th. Schindylesis, when a thin lamella of bone is re- ceived into the narrow furrow of another, as in the articu- lation of the vomer with the ethmoid and sphenoid. 5th. Go?nphosis. — This term is expressive of the mode of articulation of the teeth with the alveolar cavities, if the first be considered as bones. 2. Jlmj)hiarthrosis. — Amphiarthrosis is nothing but a mixed or synarthrodial articulation, with large, smooth, ar- ticular surfaces connected together by an intermediate fibro-cartilaginous substance, which adheres firmly to them, and has sufficient suppleness and elasticity to admit of an obscure motion. Thus the bodies of the vertebras are unit- ed, and move upon each other by turning upon their axes, or in bending forwards. The fibrous ligaments which are situated around the amphiarthrodial articulations also add to their solidity; though, they are subject at the different periods of life to the changes dependant upon those that are experienced by the intervertebral fibro-cartilages. (See Fibro-Cart. Syst.) 3. Diarthrosis. — Diarthrosis or moveable articulation/re- sults from the contiguity of osseous surfaces which are in- crusted with cartilage and lined by synovial membrane. This kind of connection takes place between the bones of the extremities and the trunk; between the os occipitis and the OF THE OSSEOUS SYSTEM. 139 vertebra dentata, and between the ribs and the vertebral column, &c. &c. The diarthrodial surfaces are sometimes plain, more frequently convex or concave, or both at the same time; but their configuration is always such that they adapt themselves readily to their corresponding parts. When the convex eminences stand out in a roundish ball and constitute the entire articular surface, they are termed heads; when they are rounded, elongated and flattened, they obtain the appellation of condyles. When the heads and condyles rise narrow, and then become larger, the nar- row or small part is termed cervix or neck, as in those of the femur and humerus. — When the depressions are deep, are more or less concave, and constitute the entire ar- tioular surface, they are denominated cotyloid and gle- noid cavities: sometimes they are designated by the names of pulleys or trochlea. The diarthrodial articulations are connected by means of fibrous ligaments, which are gene- rally attached around their circumference, and sometimes to their centre, and always in such a manner as to admit or prevent different kinds of motion. The firmness of the diarthrodial joints is less than in the other classes of articu- lations, and is generally in an inverse ratio to their mo- bility. Diarthrosis is sub-divided into several species, which differ from each other by the form of their articular sur- faces, their means of union and their quantity of motion. 1st. Planiform Diarthrosis* is the articulation where the articular surfaces are nearly plain: are connected by strong and firm ligaments, and are susceptible of vague, but obscure motions, as in the junction of the ossa cunei- formia with the os naviculare; of the articular processes of the vertebrae, &c. 2d. Jirthrodia. — When the articular surfaces are more round, less firmly united, and susceptible of more extensive motions than in the preceding. * The amphiarthrosis of Meckel and some other anatomists. 140 OF THE OSSEOUS SYSTEM. 3d. Enarthrosis, when a large head is received into a deep cavity, and is maintained there by a capsular liga- ment: this species of union admits of motion to all sides. 4th. Lateral ginglymus. — When the articular surfaces are convex in the one and concave in the other, and have a part of their circumference formed by an osseous cylinder, and the other by a ligament; as in the articulation of the radius with the ulna. 5th. Angular ginglymus, or ginglymus, properly so called. — In this articulation the surfaces present eminences and depressions, by means of which they move the one upon the other; and where, by the arrangement of these projections and the ligaments which connect the joint, the motions are confined to flexion and extension, as in the ar- ticulations of the elbow and the knee. Pathological Anatomy. The diarthrodial articular surfaces are often displaced in consequence of such efforts as have a tendency to extend or rupture the ligaments which connect them: these dis- placements are termed luxations; and, when they super- vene in consequence of organic alterations of the ligaments, they receive the appellation of spontaneous. The articu- lations are more subject to these displacements in propor- tion as they are more moveable, and their articular surfaces are smaller, and less intimately connected. Besides the accidental articulations which are sometimes established, as we have already seen between the two frag- ments of a broken bone, there are others, which are termed supplementary , and which are consequent upon irreduci- ble luxations: thus, when the articular head of a bone is removed from its cavity, it is applied against another bone, and produces a depression whose circumference is strength- ened by a fibro-cartilaginous or osseous border, while its bottom is lined by a substance analogous to fibro-cartilage: — in fact, we generally find these kinds of articulation pos^ OF THE OSSEOUS SYSTEM. 141 sessed of fibrous and capsular ligaments, &c, and of syno- vial membranes. The natural cavity becomes obliterat- ed, and assumes the form which it would have receiv- ed originally from the free development of all its os- seous points: it is in this manner that the cotyloid cavity, which is developed by three points of ossification, becomes triangular after the complete displacement of the head of the os femoris. In some instances the synarthrodial articulations become swollen and relaxed: it is in this manner that the symphy- sis pubis is separated during the last stages of pregnancy, in consequence of the swelling and softening of the inter- mediate fibro-cartilage. * In some cases this separation of the articular surfaces amounts to a considerable extent, as is observed in some of those cases which result from hy- drocephalus and the effects of external injury. The bones are sometimes firmly articulated together, either in consequence of acquired stiffness and rigidity, and the ossification of the connecting ligaments; or in con- sequence of adhesions between the contiguous parts of the synovial membrane; or in consequence of the synovial membrane, and cartilages of the articulation having been destroyed by inflammation or some other cause, the spongy extremities of the bones are brought in contact, and are united with each other: in the last case, which constitutes what surgeons have called true anchylosis, the motion of the joint is completely destroyed, while, in the preceding, * This separation of the pubes being- of very rare occurrence in the human subject, should by no means be regarded as a provision of nature intended to facilitate the delivery of the female; but as purely accidental, and as a consequence of some morbid derangement of the intermediate fibro-cartilage. In some animals, however, as the Guinea pig, this separation of the bones of the pelvis during the latter stages of pregnancy, does actually take place, and seems to be an operation of nature intended to facilitate the parturient efforts. — S. D. G. 142 OF THE OSSEOUS SYSTEM. which constitute false anchylosis, the motion is always less than in the natural state, and is also, sometimes, totally destroyed. The articulations of the elbow and the knee are more frequently affected with anchylosis than any other joints in the body. The diseases known under the name of white-swelling, depend most frequently upon chronic inflammation, and affect, either alone or simultaneously, both the soft as well as the hard parts of the articulations. Bibliography of the Osseous System. Besides the works already quoted: Malpighi. De ossium structura in op. posthum. B. S. Jllbinus. De constructione ossium, in annotat. Acad., Lib. VII, cap. 17. Delasone. Memoire sur l'organ. des os; dans les Me- moires de l'Acad. royale des sciences. Paris, 1751. J. G. Courtial, J. L. Petit et Limery. Description ex- acte des os, comprise en trois traites. j3. Scarpa. De Penitiori ossium structura commentarius. Lips., 1795, Paris, 1804. V. Malacarne. Auetuarium obs. et icon, ad osteol. et os- teopath. Lugduwigii et Scarpa?; Patav. 1801. On Osteogeny consult the following: H. Eysson. De oss. infant, cui tractatui annexus est V. Coiter ossium infantis historia. Groning., 1659. Th. Kerkring. Osteogenic foetus. Lugd.-Bat, 1717. Albi- nus. Annot. Acad., lib. VI, VII. — Id. Icones oss. foetus hum. accedit osteogenic brevis historia. Lugd.-Batav. 1737. — Duhamel, Mem. de l'Acad. royale des sciences, ann. 1739 — 41 — 43 — 46. — Haller, experimenta de oss. formatione, in op. min.II. — Hirissant, Mem. de l'Acad. royale des Sciences; 1768. — Biclard, Mem. sur l'osteose, dans le Nouv. Journ. de med., vol. IV, 1S19. — Serres, Des lois de l'Osteogenie; analyse des travaux de l'Acad. royale des Sciences, ann. IS19. — Dutrochet, observa- OF THE OSSEOUS SYSTEM. 143 tions sur l'Osteogenie, dans le Journ. de physique, sept. 1822. On the history of Callus, consult, Duhamel. Memoires de PAcad. royale des Sciences; Paris, 1741. — P. Camper, Observat, circa callum ossium frac- tor.; in Essay, and obs. phys. and litter., vol. III. Edimb., 1771. — Bonn, de ossium Callo, etc.; Amstel. 1783. — Macdonald. De Necrosi et Callo; Edimb. 1799. — Bres- chetf quelques recherches historiques et experimentales sur le cal; Paris, 1819. — J. Sanson, Expose de la doc- trine de M. Dupuytren sur le cal; dans le Journal univ. des Sciences medic, tome XX, p. 131. On the pathological anatomy of the bones, consult: Tenon. Trois memoires sur Pexfol. des os, in Mem. et ob- serv. sur Fanatomie, la pathologie et la chirurgie, etc. Paris, 1816. J. L. Bracket. Mem. de Physiol, pathol., sur ce que devi- ent le fragment de l'os apres une amputation; in Bull, de la Soc. medic, d'emul. de Paris, 1822. Chopart et Robert. De Necrosi ossium theses anat.-chir. ; Paris, 1765. — Troja, de nov. oss. Paris, 1775. — Char- meil, de la Regeneration des os. Metz. 1821. Reichel. De Epiphysium ab ossium diaphysi diductione. Lips., 1769. Jl. Bonn. Descriptio thesauri ossium morbosorum Hoviani. Amstel. 1783. — Sandifort, de ossibus di verso mo do a solita conformatione abludentibus; in obs. anat. path., lib. Ill et IV. Lugd.-Batav., 1777—81. The following works on accidental ossification may be consulted with much advantage: J. H. Van Heckern. De Osteogeni prseternaturali; Lugdu- ni-Batav., 1797. — P. Bayer, Mem. sur Possification morbide; dans les Arch. gen. de medec, tome I; Paris, 1823. 144 OF THE NERVOUS SYSTEM. CHAPTER VII. OF THE NERVOUS SYSTEM. SECTION 1. General Observations. Definition. — The nervous system is an assemblage of organs which are continuous with each other, are formed by one of the secondary elements of the animal organiza- tion — the nervous substance; and are composed, first, of masses or ganglia of different sizes, and secondly of fasciculi and cords; some of which establish communications between the different masses, while others extend from them to the different parts of the body. Division. — From remote ages to the present day, anato- mists have regarded the nervous system as composed: 1st, of a central unique part — the spinal marrow, according to Praxagoras and Bartholine, and the brain according to Ga- len and most of his successors; and 2d, of prolongations, by which they understood the nerves and all the other parts of the nervous system. Bichat, in unfolding the theories of Winslow and Reil, established the distinction of two nervous systems: the one, which he called the nervous sys- tem of animal life, consists of the spinal marrow, the brain and the nerves which are given off by them; the other, termed the nervous system of organic life, com- prehends the ganglia and the nerves which form the great sympathetic or trisplanchnic nerve. With regard to the OP THE NERVOUS SYSTEM. 145 latter, Bichat has proved that it does not consist of a sin- gle system, but of a combination of small distinct sys- tems, communicating together, and with the great cerebro- spinal system. Thus, Mr. Gall asserts, that the encepha- lon and spinal marrow are an assemblage of ganglia or in- dependent nervous systems, united by filaments of commu- nication, and susceptible of being brought under three groups. The first comprehends the nervous apparatus of the voluntary motions and of the tactile sensations, or those which form the spinal marrow; the second consists of the nervous apparatus of sense, comprehended under the name of medulla oblongata, and the third, of the cerebrum and cerebellum, or those of the faculties of the mind. A fourth group, composed of the ganglia and the trisplanchnic nerves, completes the grand nervous apparatus. The plurality of the nervous system is generally admit- ted at the present day; but many anatomists, in adopting this capital doctrine, have modified its application, and especially M. de Blainville, who, founding his opinion up- on profound study of comparative anatomy, has defined the nervous system, considered with regard to the whole scale of animal beings, to be " a number of ganglia of differ- ent sizes, each of which sending off nerves, some to be dis- tributed to the organ which it is to animate and endow with its appropriate life, and others to communicate with the other ganglia and the central ganglion (when it exists) to establish its general life." The central ganglion exists only in the higher classes of animals, and establishes, in the most complete manner, the individuality of being. M. de Blainville, in applying these ideas to the nervous sys- tem of man, represents it as being composed of a central part — the spinal marrow — at the extremities and upon the sides of which are placed ganglia that perform entirely dif- ferent functions. At its superior extremity and on the me- sian line, there are seven ganglia composing the encephalic mass, and being subservient, some to the intellectual facul- 20 1 J:i OK THE NERVOUS SYSTEM. ties; others to the senses, the partial motions of the head, and to the functions of respiration and digestion. On each side of the spinal marrow is another set of ganglia which give origin to the spinal nerves: — finally, in the splanch- nic cavities are the ganglia which are subservient to the functions of nutrition, and are situated near the organs to which they distribute their nerves; these ganglia are, the cardiac ganglion in the thorax, and the semi-lunar plexus in the abdomen. The trisplanchnic holds the same cha- racter here as was assigned to it before the time of Bichat, being an intermediate nerve to all these apparatus, and des- tined to establish communications between them, and in a word, to be a true sympathetic nerve. We repeat here, that the doctrine of the plurality of the nervous system is generally admitted in the present day, and that authors differ only in regard to the application of this capital idea. The manner in which M. de Blainville regards the grand apparatus of which we are treating, is undoubtedly that which is the most expressive of the ge- neral laws of organization. Although the ideas of this anatomist are not as yet generally adopted, it becomes us, in a work of this kind, to adopt the division of the nervous system into the cerebrospinal and the trisplanchnic, a di- vision, which will at once facilitate the description of this system, and enable us to give an account of the different opinions of the physiologists that have written upon this subject. Situation. — The nervous system is spread throughout every region of the body: its central parts are situated in- teriorly, while its large cords are more superficial, and ap- proach nearer towards the periphery in proportion as they ramify: we shall have occasion to see, however, in a sub- sequent part of this work, that there are some important differences with regard to the situation of the two divisions of the nervous system. Form and general arrangement. — The nervous sys- OF THE NERVOUS SYSTEM. 147 tern may be represented as a grand net-work, whose fila- ments, being interrupted by the small ganglia in the dif- ferent regions of the body, and united together by fre- quent communications, extend from the periphery of the body to the brain and spinal marrow, diminishing in num- ber, and acquiring, generally, a larger volume, and a more completely symmetrical arrangement in the two lateral halves of the body: this arrangement is more perfect in the brain and spinal marrow than irPany other part of the ner- vous system. Texture. — The nervous system is far from having the same organization in every part, notwithstanding in this respect it presents the same common characters. Every part is formed of a peculiar substance called the nervous fibre, which has been regarded by M. de Blainville as a secondary element, resulting from the modification of the primary or cellular element of our bodies. This nervous substance is presented under two principal aspects, which has led to the distinction into the white and gray sub- stance. We shall presently see that this distinction does not merely rest upon the difference of colour indicated by these denominations. 1. White substance. — The white substance of the ner- vous system forms a continuous whole, and is generally surrounded by the gray substance; but this is not the case everywhere, as the term medullary, which is also some- times used to designate it, would appear to indicate. If its consistence be increased by immersing it in alkohol, or in weak solutions of the nitric or muriatic acids, upon di- viding it, it will exhibit a very remarkable fibrous struc- ture, apparent in some parts, as in the nerves without pre- vious preparation. The fibres are disposed in parallel or oblique fasciculi, which can be readily separated into capilli- form fibrilke; but the mechanical division can not be carri- ed so far as to enable us to say whether these filaments, which are very intimately united together, are themselves 14S OF THE NERVOUS SYSTEM. composed of other still more minute fibrillae. The white substance is plentifully supplied with blood-vessels, but not so much so as the gray. 2. Gray substance. — The gray substance is generally situated externally to the white; so that it is often called cortical — a term which is by no means always applicable, as we shall see in the next section. It does not, like the white substance, form a continuous whole; but is always found in insulated portions; This substance occurs at the central extremities or points of origin of the nerves, and is there more abundant in proportion as the nerves are larger and more numerous, as in the superior part of the brachial plexus: it is found, also, every where where the white sub- stance is most abundant and more fully developed. From this disposition, many physiologists have inferred that the gray substance produces the other, and is the matrix of all the nerves. If this were true, the appearance of the first would necessarily precede that of the second, which is not the case, as we shall presently see. The fibrous texture of the gray substance being difficult to be distinguished, even when prepared as we shall hereafter direct, is not admitted by all anatomists, though its exist- ence does not appear to be doubted at the present day, at least not in the encephalo-rachidian mass. The gray sub- stance is generally very vascular; but variously in the dif- ferent parts of the system. Examined with the microscope, the nervous substance appears to be composed of small, semi-transparent globules, connected together by a viscid substance, irregularly dis- posed according to some, (as in the brain;) and according to others, in linear orders, (as in the nerves,) so as to form extremely delicate fibres. Anatomists are not perfectly agreed as regards the volume of these globules; some assert that they differ in the different parts of the nervous system, and agree to locate the largest in the encephalon; while others, equally positive, affirm that their diameter is every- OF THE NERVOUS SYSTEM. 149 where the same. According to the late researches of M. H. M. Edwards, their diameter is equivalent to 1-3000 part of an inch. As to the nature of the globules, the Wenzells, who have made a great number of observations, regard them as vesicles containing a white or grayish substance, accord- ing to the parts in which they are situated; but all our knowledge upon this subject is still involved in doubts and hypotheses. The globules appear to be connected together by extremely delicate cellular tissue, which also connects, and in a very intimate manner, the small delicate fibres which result from their linear disposition. The cellular tissue, which is more compact on the surface than in the interior of the nervous organs, forms a thin membranous layer, having different names, and varying in different parts, as we shall have occasion to point out in the following sec- tions. This membrane is exceedingly vascular, and the vessels which are distributed upon it, penetrate the nerv- ous substance, and are, as we have already said, more nu- merous in the gray than in the white substance. The nervous system appears to be destitute of lymphatic ves- sels. Characters, physical and chemical properties. — The nervous organs are very excellent conductors of the elec- tric fluid. The two substances do not everywhere pre- sent the same shades of their respective colours; the grayish substance, especially, varies so much, that in some places it is yellowish, ash-coloured, and even black; these differ- ences of colour, however, depend uniformly upon the de- gree of vascularity of the part. The consistence of the medullary substance is by no means the same in every part of the nervous system; but it is always in relative pro- portion to that of the cortical: both, but especially the medullary substance, are slightly elastic, retractile, and more resisting in the direction of their fibres than in any other. When macerated, the nervous substance resists for a long time the action of water, and its first effect is a 150 OF THE NERVOUS SYSTEM. softening and slight discoloration of the cortical substance. The effects of the dilute acids and of alkohol, upon the cortical and medullary substances, have been already pointed out. By desiccation the former is rendered brit- tle and pulverizable, and both are rendered hard by solutions of the bi-chloride of mercury. According to the analysis of M. Vauquelin, the nervous substance is composed of the following ingredients: — a white fat, 4 53; a reddish brown liquid fat, called cerebrin,* by M. Chev- reul, 0.7; water, 80; albumen, 7.0; osmazome, 1.12; phos- phorus, 1.5; phosphate of potash, muriate of soda, phos- phate of lime, and phosphate of magnesia, 5.15. The quantity of albumen is in an inverse ratio to that of the fatty matter, which is most abundant in the spinal marrow, less in the brain, and quite small in the nerves: the phos- phorus appears to exist only in the medullary substance. The analysis of Vauquelin has no reference to the grayish substance of the ganglia of the great sympathetic. Order of development and differences according to age. — We have no positive knowledge with regard to the time in which the nervous system begins to be perceptible, nor of the state in which it is at its origin. It appears, however, to be one of the first of the systems that are de- veloped. Its different parts are not formed simultaneous- ly, but in a gradual and successive manner;! and though authors are not agreed upon the order of this succession, it would appear sufficiently evident that the nerves and their ganglia appear first; then the medulla spinalis, and finally, the different parts of the encephalon. This general order, and that which we shall point out hereafter, when speaking of each part of the central masses in particular, correspond to that in which the nervous system is pro- * According 1 to M. Chevreul, this substance also exists in the blood. t This progress of the development of the nervous organs is not, as the ancients thought, the result of a vegetative elongation of the pri- mary parts of this system. OF THE NERVOUS SYSTEM. 151 gressively complicated in the animal scale, in ascending from the inferior to the higher classes. This fact consti- tutes the principal anatomical proof of the plurality of the nervous system. Mr. Gall is of opinion that the grayish substance is formed previously to the medullary; but ac- cording to M. Serres, this is true only with regard to the encephalon. According to the researches of Tiedemann, and other anatomists, the medullary substance appears al- ways before the cortical; and this opinion appears to have the most probabilities in its favour.* Be this as it may, it is certain that the nervous substance passes through all the intermediate gradations between fluids and solids, being soft in infancy, and acquiring consistency by degrees. The growth of the nervous organs is effected by interstitial nu- trition, and by the deposition of layers upon their surfaces, which are, apparently, secreted by the cellulo-vascular mem- brane by which they are covered. This growth, which is extremely rapid during foetal life, becomes gradually slow- er after birth, until it is finally converted into a simple nutritive process, which itself diminishes, so that at length in old age the organs of which we are treating, have sensi- bly lost a share of the volume which they had acquired in adult age. Vital properties and functions. — The nervous system is essentially sensible, but in such degrees and conditions as vary according to the different parts of which it is com- posed. It is to its presence in the other organic systems that are owing the phenomena of the sensibility which they enjoy. This sensibility of the organic systems is nothing but a modification of a property belonging exclusively to the nervous system — a property, which physicians have designated by the names of vital energy, nervous power, * The circumstance which has led physiologists into error as regards this subject is, that in the foetus, the medullary substance is slightly co- loured, which is owing to its being more penetrated by the fluids dur- ing pregnancy than at any other period . 152 OF THE NERVOUS SYSTEM. and by virtue of which, it animates the whole animal economy, and performs the most important functions. Physiologists have at all times endeavoured to ascertain the nature of this property : how far they have succeeded will appear from the statement of the principal hypotheses, after we shall have described, in a general manner, the ac- tions which depend upon it. The nervous system is the apparatus of innervation, a multiple function, at least as to its results, by which it ani- mates all our organs, presides over all their vital actions, both voluntary and involuntary, transmits and receives the sensorial and affective impressions, and is the agent of the operations of intelligence. Every part of the nervous system has its determinate function. In the inferior animals, the small apparatus which compose this system, are independent of each other, and their actions are less rigidly specified; but in ascend- ing the scale to the higher classes, we find the functions are multiplied in proportion as the nervous system becomes more complicated; at the same time that these functions, though always distinct, become less and less independent, and are placed, moreover, under the influence of a centre of action, whose integrity is necessary to their perform- ance and regularity. This physiological centre of action, to which we have just alluded, is the encephalon, and par- ticularly the medulla oblongata, upon which depend all the other parts of the nervous system, as well as the functions which they perform, in proportion as they have less for their object the nutrition of the individual. The grayish substance of the nervous tissue, as has been demonstrated by Mr. Tiedemann, increases the activity of the medullary, by concentrating a greater quantity of blood towards the parts where this activity is more essen- tially necessary: thus the substance of which we are speak- ing is very abundant in the medulla spinalis, at the origin OF THE NERVOUS SYSTEM. 153 of the nerves, and more so in proportion as these are larger. Physiologists have not been contented with merely re- ferring the faculty of the senses and innervation to a peculiar property of the nervous system, but they have also endea- voured to ascertain the nature of these functions. The hy- potheses that have been advanced upon this subject, may be reduced to two principal ones, both very old. Accord- ing to the first, which has had the smallest number of sup- porters, the nerves perform their functions by the centri- petal and centrifugal transmission of vibrations, excited in the one case by external agents, and in the other by the brain, the point of egress of innervation and volition. In- dependently of the fact that this hypothesis is founded upon no direct experiment, it would be entirely inadmis- sible from the circumstance, that the nerves are too soft to perform the office of vibrating cords. The second suppo- sition has had by far the greatest number of partizans, and ranks amongst its number, the most celebrated physicians of both ancient and modern times, and amongst others, the immortal Galen, Baglivi, Boerhaave, Haller, &c. This hypothesis consists in the admission of a subtile fluid which is secreted by the brain, and is designated by the names of nervous fluid, animal spirit, and pervades the nerves with the greatest rapidity, from their cerebral to their periphe- ral extremity, and vice versa-, transmitting to the centre of the nervous system the impressions which are received by the sentient extremities of the nerves, and carrying to the organs, the volitions and the nervous influx emanating from the brain. Some have even gone so far as to imagine there are two fluids, destined, each to one of these motions, and so subtile, that they might traverse the same nervous cords, in an inverse direction at the same instant: while other physiologists, to explain the differences of the sensa- tions in the brain, and of the volitions, &.c, which are de- rived from it, have combined the two hypotheses, and have 21 154 OP THE NERVOUS SYSTEM. attributed the first to vibrations, and the second to animal spirits. Finally, this association of hypotheses, has been inverted, and the hypothesis of animal spirits has been modified in various ways. No sooner was this admitted, than physiologists, anxious to ascertain its nature, advanc- ed the most absurd and ill founded propositions; so that the only one, which is at all plausible and worthy of our attention, is that which compares the nervous agent to the electric fluid. In the present day, physiologists are contented with ob- serving the laws of innervation, and, if they go beyond this, it is with the view of drawing conclusions from the remarkable analogy which exists between certain effects of electricity upon the animal organization, either dead or liv- ing, and the vital phenomena, which allow us to presume the existence of an imponderable agent, which presides over, and regulates the functions of the nervous system. section 2. Of the Nervous Centres. ARTICLE 1. Of the Cerehro-Spinal Centre Definition. — By the term cerebro-spinal, we under- stand, with most modern authors, the mass of nervous sub- stance which is contained within the cavities of the cra- nium and the vertebral column.* * We must recollect that this mass comprehends, according' to Messrs. Gall and de Blainville, a series of ganglia, so many centres of small sys- tems or nervous apparatus, and having, according to the latter physiolo- gist, a common centre — the spinal marrow: these divisions, however various they may be, are not in contradiction with the ancient denomina- tion of cerebrospinal centre, — a collective denomination which is applied to every division of this continuous mass. OF THE NERVOUS SYSTEM. 15.5 . Division. — The cerebro-spinal centre is composed (a) of the medulla spinalis; and (b) of the encephalon, which comprehends the medulla oblongata, the cerebrum and cerebellum. Situation. — (a) The medulla spinalis is situated within the vertebral canal which is formed by the vertebrae of the neck, the back, the loins, and the sacrum; but in the hu- man subject, it extends only from the superior part of this canal to a level with the second lumbar vertebra. (b) The encephalon is situated at the superior part of the medulla spinalis, with which it is continuous, and fills com- pletely the cavity of the cranium. Form and arrangement. — (a) The spinal marrow is a large nervous fasciculus, irregularly cylindroid, divided into two lateral symmetrical halves, by two fissures which ex- tend throughout the whole length of its anterior and pos-ii terior surfaces. Each lateral half comprehends two fasci- culi, an anterior and a posterior, whose line of demarcation is marked out by the insertion of the ligamentum denticu- latum. The spinal marrow is more voluminous superiorly than inferiorly, but its decrease is by no- means uniform: it enlarges where it gives off the nerves, and this in propor- tion to the size of the nerves which are separated sym- metrically from its lateral parts, to the amount of thirty pairs. Superiorly, the spinal marrow enlarges considera- bly in entering the cranium, where it begins the encephalon under the name of the medulla oblongata. Here it presents three pairs of lateral and symmetrical fasciculi: the anterior, which is disposed on the sides of the mesian fissure, con- stitutes the pyramidal fasciculi, which, after having inter- changed fibres, form the peduncles and hemispheres of the cerebrum;*the second pair comprehends the middle fasciculi, * We ought not to understand by the word " to form" a real vegeta- tive growth; it is merely expressive of the order of development and of the connexion of the different parts of the encephalon. 156 Or THE NERVOUS SYSTEM. which are situated on the outside of the preceding, and which, being reinforced by the corpora olivaria, terminate in the tubercula quadrigemina; the third pair or the pos- terior fasciculi, are strengthened by the corpora restiformia, and form the cerebellum and tuber annulare, which em- braces the base of the medulla oblongata. All these fasci- culi give rise to smaller ones which communicate with, and establish relations between, every part of the encephalon. — The encephalon, regarded as a whole, constitutes a ta- bulated mass, irregularly hemispherical, composed of sym- metrical portions, presenting depressions and correspond- ing eminences, and, in short, a very complicated struc- ture, for a minute description of which, we must refer to descriptive anatomy. The medulla oblongata is the only part of the encephalon that gives origin to nerves. — The ^encephalo-rachidian mass is surrounded and protected by three kinds of membranes; the external belongs to the fibrous system and is termed the dura mater; the middle is a kind of serous membrane, and is called the tunica arach- noides; the internal is the pia mater, a very delicate cellulo- vascular net-work, applied immediately upon the nervous masses, lining all the sinuosities upon the surface of the encephalon, and dipping into the anterior and posterior furrows of the spinal marrow. We must recollect that Mr. Gall considers the medulla spinalis and the encephalon as a series of ganglia connected together by intermediate fasciculi, and that M. de Blainville professes a nearly simi- lar opinion, with the exception that he regards the spinal marrow as a single ganglion — the centre of all the others; and reduces the encephalic ganglia to seven pairs, as we have already seen in the preceding, section. Texture. — It is only in the cerebro-spinal mass that we observe the two kinds of nervous substance, the white and the grajash. Their relations of situation and quantity vary in the different parts of this mass; thus, in the spinal marrow, the grayish substance is interiorly and surround- OF THE NERVOUS SYSTEM. 157 ed by the white, which is disposed around it in the form of a layer: — the grayish substance is most abundant at the points where the large nerves are given off. In the ence- phalon, on the contrary, the grayish substance forms the exterior and cortical layer of the hemispheres of the cere- brum and cerebellum, while the white, which is surround- ed by it, composes the whole interior of these parts. Be- sides, in the medulla oblongata, the peduncles of the cere- brum and cerebellum, &c, we meet with masses of the grayish substance, which are enveloped by white fibres, (origin of the encephalic nerves), and alternate layers of both substances, &c. In this variety of arrangement, there is but one general law — that of the continuity of the white substance throughout the whole encephalo-rachidian mass, and the insulation of the different parts of the grayish. The fibres of the medullary substance, the only ones that are at all conspicuous, are much less apparent in the cere- brospinal mass, than in the nerves; they are parallel in the two fasciculi of the spinal marrow, which are connected together by transverse fibres, and not, as some anatomists have asserted, by a decussation of their filaments. There is nearly the same arrangement with regard to those of the medulla oblongata, with the exception that they are more divergent, and that those of the two anterior or pyramidal fasciculi are interlaced upon the mesian line. The fibres of the peduncles of the cerebrum and the cerebellum proceed in radii to form the hemispheres of these organs, and, if we may credit Mr. Gall, these diverging fibres, after hav- ing reached the grayish substance that forms the cortical layer of the hemispheres, are reflected upon the mesian line, under the name of the converging fibres, to form the corpus callosum and the commissures. This manner of observing has been disputed by Mr. Tiedemann, who re- gards the cerebral commissures and the corpus callosum as being derived from the cerebral peduncles. The cortical substance of the cerebrum and the cerebellum is so abun- 15S OP THE NEltVOUS SYSTEM. dantly supplied with blood-vessels, that, when well inject- ed, it appears to be almost entirely composed of them. To judge of the vascularity of both the white and the cor- tical substances, it will be sufficient merely to tear them; we shall then observe that they are covered with small reddish points, which are more or less conspicuous, and are more numerous in the grayish than in the medullary sub- stance: these points are the extremities of the small blood vessels that have been ruptured. Characters, physical and chemical properties. — To what we have already said upon this subject in the gene- ral observations of the nervous system, we have only to add, that the consistence of the encephalo-rachidian mass is much less than that of the nerves. Order of development, and differences according to age. — The spinal marrow is developed before the ence- phalon, and amongst its different parts, the medulla ob- longata is the first that comes into existence; this, which is nothing but the superior portion of the spinal marrow, has added to its fasciculi in a gradual and successive manner, the cerebellum, the tubercula quadrigemina, and the cere- brum. The cerebellum and the cerebrum are much larger, com- pared with the spinal marrow, in proportion as the subject is farther advanced in age; while the tubercles are much larger compared with the brain, as the foetus is younger, and are bigeminous before they are converted into the quadrigemena. The hemispheres of the cerebellum are at first equal to the middle lobe (vermiform process), but as they increase, they greatly exceed it in size. The cere- bral hemispheres form by far the larger portion of the en- cephalon, and project farther backwards in proportion as the nervous system is more perfectly developed. All that we have just observed with regard to the human foetus is equally applicable to the different classes of vertebral ani- mals. OF THE NERVOUS SYSTEM. 159 The encephalo-rachidian mass is at first nothing but a semi-fluid substance, which subsequently and by degrees, assumes the characters of the white nervous substance, and finally unites with the grayish substance which is se- creted by the pia mater. In old age the spinal marrow and the encephalon become more dense, and there is a very sensible diminution of volume. Vital properties and Junctions. — Although the ence- phalon and the spinal marrow enjoy the highest degree of nervous energy, there are not wanting some who have en- deavoured to deny the sensibility of the brain. This error would not have been committed, if physiologists had been aware of the fact that, though there are some organs which can not be rendered painful by external irritants, they may be all excited by internal causes, whether physiological or .pathological. We have already seen, that modern anatomists, in ad- mitting the plurality of the nervous system, recognize an assemblage of distinct masses or ganglia in the cerebrospi- nal centre, and attribute to each of them a determinate function, which it exercises in virtue of its nervous energy, and which is placed under the influence of a common cen- tre. By thosfe (Magendie) who do not consider with M. de Blainville, that the spinal marrow is the central part of the nervous system, it is regarded as the seat of general sensibility. The posterior part of the spinal marrow, some parts of the medulla oblongata, and according to some, the cerebellum, appear destined especially to the external sen- sations. The anterior portion of the spinal marrow, that of the medulla oblongata which gives rise to the motor nerves of the face, and, according to Magendie, the cere- bellum and some parts of the base of the cerebrum, preside over the voluntary motions. Finally, the cerebrum is the seat of the internal or affective sensations and of the intel- lectual faculties. The spinal marrow is really nothing but an organ of transmission; perceptions and determinations 160 OF THE NERVOUS SYSTEM. belong to the cncephalon. The portion of the medulla ob- longata from which originate the peduncles of the cerebrum and the cerebellum, appears to be the physiological centre of the encephalo-rachidian mass, and consequently, of the Avhole system. Nevertheless, physiologists have come to very different conclusions with regard to the parts of this mass which correspond to the different functions of inner- vation. Pathological Jinatomy. There are observations which would induce Us to believe that the brain is susceptible of undergoing a diminution of volume before old age, but it does not appear that it is ever subject to hypertrophia. The conformation of the cerebro-spinal masses, is sometimes altered by the pres- sure of tumours situated in their neighbourhood. The spinal marrow is often compressed by curvatures of the spine, and altered in its form, though most frequently without creating any disturbance in its functions. The solutions of continuity of the encephalon and the spinal marrow, when they do not terminate fatally, heal, like those of the other organs, either by immediate re-union, or by the formation of a brain-like substance, which is depo- sited upon the points that have been left open from the loss of substance, or by the simple separation of the lips of the wound. In cases of apoplexy and in certain cerebral dis- turbances, where there is an effusion of blood or serum into the nervous tissue, if the subject be young, the fluid is soon surrounded by a cyst, and is gradually absorbed;* and its parietes approximate and form adhesions so as to com- pletely obliterate its cavity. The organs of which we are treating are very frequent- ly subject to sanguineous congestions, which can be readi- * In tliis case, the blood is decomposed into its two elements, the clot and the scrum, and becomes really a foreign bod}-. OF THE NERVOUS SYSTEM- 161 ly explained by the great quantity of blood which they receive, and by the facility with which it exalts their ac- tivity. Inflammation of these organs is by no means a rare disease, and is generally accompanied by that of the meninges. Inflammation of the encephalon and medulla spinalis is characterized by the redness and softening of their substance, and sometimes, by suppuration, ulceration, and even gangrene. The sub-inflammatory state of the nervous central masses may also give rise to the secretion of purulent matter, which is sometimes collected in a sin- gle abscess, in the substance of the organ, and excites the formation of a cyst in which it remains for a variable time; at other times, the secretion is nothing but serum, which is collected either in the ventricles of the brain, or in the nervous substance itself, or between the organ and its en- velopes: when this is the case, it constitutes what physicians call acute hydrocephalus, a disease which diners from chro- nic hydrocephalus, inasmuch as the latter, which is most generally congenital, is not accompanied by any inflamma- tory process. When this affection attacks the spinal mar- row and its coverings, it is termed hydro-rachitis, of which the disease termed spina-bifida is a remarkable variety. In consequence of the chronic phlegmasia, the cerebro-spinal centre is also sometimes affected with tuberculous, schir- rous and carcinomatous degenerations, fungous growths, and fibrous, fibro-cartilaginous, and osseous transforma- tions. Hydatids are also found in some instances in the ventricles of the brain, and even in the substance of the encephalon and the spinal marrow. These organs are often subject to considerable softening, attended with a very va- riable change of colour; in many cases this alteration is evidently the result of chronic inflammation. Induration of the encephalo-rachidian mass is another disease which exists either by itself, or in union with the preceding. The indurated substance, sometimes perfectly homogeneous, and, in appearance, inorganic, resembles coagulated albu- 22 162 OB' THE NERVOUS SYSTEM. men; at others, however, it is more evidently fibrous. This alteration appears to be more peculiar to the white sub- stance. The brains of idiots, epileptics, &c. are frequently- indurated and softened to a greater or less extent. The encephalon and spinal marrow are by no means ex- empt from mal-conformations: the entire absence of these organs, especially of the encephalon or some of its parts, is not an unfrequent occurrence. From the existence of the rest of the nervous system, under these circumstances, it is evident, that every part of it is independent as regards its development and origin. In the early age of the foetus, the spinal marrow presents a longitudinal groove on its posterior surface, and subsequently a central canal*, some- times we observe the one or the other of these arrange- ments at birth; at others, this organ is entirely wanting, and in its stead, the pia mater forms a canal which is filled with a fluid, and gives insertion, as it naturally does, to the roots of the spinal nerves. Amongst the defects of symmetry which are sometimes, though rarely observed, between the different parts of the nervous central masses, we may notice the disproportions which occur between the lobes of the cerebrum. article 2. Of the Nervous Ganglia. Definition. — The nervous ganglia are small masses, ir- regularly rounded, and situated on the course of the nerves.* * We have seen that Gall and De Blainville have also applied the term ganglion to the divisions of the cerebo-spinal masses; this generali- zation, a natural consequence of then- manner of regarding the nervous system, gives this expression an exclusively physiological sense: but it should not be used when we consider the ganglia in a less exclusive point of view — under that of their structure. OF THE NEKVOUS SYSTEM. 163 Division. — The ganglia are divided into two classes; the first comprehends those which belong to the cerebro- spinal nerves, and the second those which occur in the course of the trisplanchnic nerve: the latter may again be subdivided into those which form a double series upon the sides of the vertebral column, and into those which are more immediately upon the mesian line. Situation. — The nervous ganglia are found exclusively in the head, the neck, and in the cavities of the thorax and abdomen; there being none in the extremities. The ganglia of the first class occur near the central extremity, or origin of some of the encephalic, and at the posterior roots of all the spinal nerves. Amongst the ganglia of the second class or of the trisplanchnic nerve, some are lateral, and placed in a double series upon the sides of the anteri- or part of the vertebral column, and are designated by the names of the cervical, the thoracic, the lumbar and the sacral ganglia; in this enumeration ought to be included the small coccygean ganglion, which, though it is single and situated upon the mesian line, belongs to this series. The other ganglia of the second class are more immediately upon the mesian line, and are termed the cardiac and semi-lunar. Form and volume. — All the spinal ganglia are of an oval form; amongst the others, some are oblong, others ir- regularly globular, and, in a word, of a very different form. Their volume varies from that of a lentil to that of an al- mond. Structure. — On dividing of the ganglia, their tissue appears at first sight to be homogeneous; but after they have been subjected to maceration for some time, we find that there are two substances, that contribute to their composi- tion: the one is white or medullary, and is disposed in fila- ments in the same manner as in the nerves; the other is of a grayish red, somewhat pulpy, different from the grayish substance of the encephalo-rachidian mass, deposited in cells, and firmly adherent to the medullary filaments, and 164 OF THE NERVOUS SYSTEM. more consistent in the ganglia of the trisplanchnic than in those of the medulla spinalis. The medullary filaments are evidently the continuation of those which constitute the nerves upon whose course the ganglia occur. In entering the ganglia, the cords are deprived of their neurilema. and are divided into filaments, which, after having plunged into the grayish substance with which they are intimately connected, especially in the ganglia of the trisplanchnic, are separated from each other to re-unite and anastomose in such a manner as to present a very complicated arrangement in the ganglia of the second class, and sufficiently simple in those of the first. The medullary filaments, being again united with the cord, issue from the cerebro-spinal ganglia by the ex- tremity opposite to that by which they entered, while, in the ganglia of the trisplanchnic, the points of entrance and of egress of these filaments are in very different rela- tions of situation. All the nervous ganglia are enveloped by a more or less dense membrane which, in the spinal, has the solidity of fibrous tissue, while in the other ganglia it is merely a membraniform layer of cellular tissue. The blood vessels of the ganglia are exceedingly numerous, and most of them send branches to their envelopes before they enter the ganglia themselves.* Characters, physical and chemical properties. — The ganglia are of a grayish red colour, which is most conspi- cuous in those of the trisplanchnic, which are also harder than the others. When exposed to the action of the acids and of boiling water, they are at first hardened and final- * In comparing these details upon the structure of the ganglia with what we shall hereafter say with regard to the nervous plexus, we shall see whether the relations which exist between them will justify the opinion of Scarpa, and other authors who regard the terms ganglia and plexus as synonymous. The texture of the first is evidently more com- plicated than that of the second, and their uses, moreover, do not appear to authorize this approximation. OF THE NERVOUS SYSTEM. 165 ly softened; they are slowly dissolved by the alkalies. They resist for a long time the putrefactive process; and, according to Lobstein, are converted into a kind of adipose substance after long continued maceration.— The reddish substance of the ganglia does not consist of fat, as has been asserted by some who have adopted the opinion of Scarpa upon this subject. According to the chemical researches of Wutzer and Las- saigne upon the composition of the ganglia, they contain less adipose substance than the nerves, and much less than the brain, but on the contrary more albumen and gelatine. Development and differences according to age. The spinal ganglia come into existence before any of the others, and even before the rest of the nervous system, with the exception of the nerves which belong to them. The gan- glia of the trisplanchnic are not perceptible before the third month of uterine life: they are all from the beginning of nearly the same consistence which they present during the course of life. In old age and decrepitude they become smaller, harder, and of a fainter colour. Vital properties and functions. — All the ganglia, both of the cerebro-spinal and of the trisplanchnic order, are desti- titute of contractility, and the nervous energy appears to be distributed to them in the same manner as to the other por- tions of the nervous system; though it seems to be more energetic in the spinal ganglia than in those of the second class, at least, if we may judge from the severe pain which accompanies their mechanical or chemical irritation; while those of the trisplanchnic are entirely free from pain when they are the seat of irritation brought on by some internal cause. The history of the functions of the ganglia is still involv- ed in the greatest obscurity. According to some, such as Meckel and Scarpa, they are destined to collect and blend the nerves or the nervous filaments; others, such as Vieus- sens, Winslow, Reil, Bichat, and others, regard them as fo- cal centres of the nervous action, presiding over those func- 166 OF THE ISERVOUS SYSTEM. tions of innervation which are independent of volition, that is, over the actions of vegetative life. This opinion, which does not concern the ganglia of the trisplanchnic, is that which is most generally adopted at the present day. Many suppose, also, that the ganglia arrest, to a cer- tain degree, the impression which they receive from the nerves which traverse them; that they concentrate for dis- tribution, the nervous energy emanating from the medulla spinalis, and that in this manner the trisplanchnic sys- tem is rendered independent of the cerebro-rachidian masses: we ought not, however, as the authors to whom we have just alluded, exaggerate this independence, which is merely relative. As yet we are entirely ignorant of the functions of the encephalic and spinal ganglia; M. de Blainville considers them as the centres of the nerves to which they belong. Alterations. — This part of the history of the ganglia is still involved in the mists of obscurity. Several authors, and amongst others Mr. Lobstein, have observed inflamma- tion of these organs in several diseases, such as tetanus, pertussis, and in some of the abdominal neuroses. Bichat once found the semi-lunar ganglion more dense, and in another instance more voluminous than natural: this last anomaly was accompanied by the presence of a cartilaginous substance in the centre of the small organ: the subject that presented it had died in consequence of a periodical ma- nia. Anatomists have also observed cases of hypertrophia and atrophia of the ganglia of the trisplanchnic; and, indeed, it would appear probable that most of the abdominal neu- croses depend upon an alteration of these organs. OF THE NERVOUS SYSTEM. 167 SECTION. 3. Of the Nerves. ARTICLE 1. Of the Cerebro-Spinal Nerves. Definition. — The cerebro-spinal nerves are the white cords, which are connected by their central extremities to the substance of the encephalon or the spinal marrow, and terminate, after successive ramifications, in certain organs which are more or less near the periphery of the body. Division. — We may divide the nerves, according to the seat of their central extremity, into encephalic and rachi- dian; according to the manner in which they are detached from this extremity, into nerves with a double, and into those with a single root; and, finally, according to their functions, into the sensitive, motor, and mixed. Each of these last divisions is again subdivided before it comes un- der the last term of specification: this subdivision can not be pointed out on the present occasion without anticipating some of the subjects of this article. Situation. — The central extremity of the nerves of which we are treating, is situated within the cavities of the cranium and the vertebral column; and the other approaches the periphery of the body in proportion as the nerves ramify. Conformation. — In consequence of their numerous anas- tomoses, the cerebro-spinal nerves, considered as a whole, represent the form of a grand net- work, which is much more symmetrical in its two lateral halves, in proportion as it approaches the nervous centres. Their particular in- dividual form is generally cylindrical; some of them, how- ever, are flattened and ribband-like. Examined with a 168 OP THE NERVOUS SYSTEM. magnifying glass, their surface presents small spiral folds, which belong, however, merely to the neurilema. Central extremity ', improperly called the origin of the nerves. — All the encephalo-rachidian nerves communicate by their central extremity with the spinal marrow, or the medulla oblongata; there being none detached either from the cerebellum or from the brain properly so called-. The nerves are always implanted in the grayish substance of the spinal marrow, and the medulla oblongata, and may be traced farther than the point where they are separated. They do not intercharge filaments at their origin, as has been supposed by those who have endeavoured to explain in this manner the symptoms of paralysis, and partial con- vulsions in the lateral half of the body opposite to that in which the lesion occurred.* By the root of a nerve we understand its central extremity, and, according as it is single or bifurcated, we say that the nerve has one or two roots. All the encephalic nerves belong to the first class, with the exception of the trigeminus, which, together with all the spinal and the sub-occipital nerves, is comprehended in the second. — The nerves with double roots are attached by the one, to the anterior fasciculi, and by the other, to the posterior fasciculi of the spinal marrow. It is to the pos- terior roots alone that the spinal ganglia belong — the ante- rior roots being simply appended to them. Course. — In receding from their central extremity, the nerves are successively divided into branches, smaller branches and filaments, by the simple separation of the fasci culi and the cords, by the union of which their trunk is com- posed. In their course, the nerves form connexions either between themselves, or with the neighbouring nerves, by simple anastomoses, or by a kind of complicated interlace- ment, termed plexus. The anastomoses take place by the * The optic are the only nerves which decussate, and this only in a partial manner, and after their separation from the encephalon. — In fishes this decussation is complete. OP THE NERVOUS SYSTEM. 169 junction of two nerves, which are very intimately united by the continuity of substance, and are finally confounded with each other. The plexuses are anastomotic unions be- tween several nerves which converge towards one com- mon point: these anastomotic junctions are formed in such a manner, that the nerves which issue from the plexus con- sist of filaments which are derived from all the nerves that enter into the formation of the plexus. The cervical, lum- bar, sacral, and sciatic plexuses are the principal of the cerebro-spinal system. The nerves generally retain the same volume from their origin to the place where they are divided j and the aggregate of their divisions presents a greater volume than that of the trunk from which they are derived. Peripheral extremity ', or termination. — After repeated and numerous ramifications, the cerebro-spinal nerves ter- minate in the integuments, in the organs of the special senses, in the exterior muscles, in the arteries of the parts which are subject to the influence of volition, &c. When they have arrived at their termination, the nervous filaments are deprived of their neurilema, and become sensibly en- larged: and this is all that we know positively upon this subject. Amongst the anatomists that have endeavoured to penetrate farther, some have supposed, but have never de- monstrated, the existence of a kind of fusion of the nerve in the substance of the organ in which it terminates; others have said, that the nervous filaments, after they have ar- rived at their termination, are reflected upon themselves, and return to the branch from which they have been derived. Structure. — At first sight, the nerves seem to be compos- ed of a certain number of cords which are divisible into fila- ments of great tenuity: these are composed, 1st, of a white nervous substance, disposed in parallel fibres;* and 2d, of a * According 1 to the recent observations of Prevost and Dumas, the nerves are composed of a very greatnumber of parallel filaments which are of equal size, and are flat and continuous throughout the whole length of 23 170 OF THE NERVOUS SYSTEM. membranous sheath or envelope termed neurilema. All the filaments which enter into the composition of the nervous cords, have, besides their proper neurilema, a common one; and in the same manner all the cords which enter into the composition of the nerves have a general neurilema. The nervous cords are placed upon each other, give off filaments of communication, and present a plexiform union : the same arrangement is found between the filaments, which, by their union, constitute the cord; so that neither the one nor the other retain the same situation throughout the whole extent of the nerve. Towards the central extremity of the nerves, the neu- rilema leaves first the filaments, then the cords, and where the nerve is continuous with the pia mater, the gene- ral neurilema alone remains. It results from this arrange- ment, that when a nerve is torn from the central mass, its interior part will break before those which are strengthen- ed by the general neurilema, and leave a projection, which is believed by some to be destined for the insertion of the nerve. We have already seen that the neurilema leaves the nerve entirely at its peripheral extremity. The nerves are surrounded by a layer of cellular tissue, which penetrates between their cords and filaments, so as to unite them mutually together. The neurilema itself is nothing but a condensed cellulo-vascular tissue, which some anatomists have placed in the fibrous system. No lym- * the nerve. Each filament consists of four elementary fibres; two external, and well marked, and two middle and less distinct. These fibres are form- ed each of a series of globules, like those of every part of the nervous system. Bogros asserts that he has demonstrated by minute injections, which do honour to his skill, that the nervous pulp is hollow in the cen- tre of the nerves. His experiments have been repeated by other anato- mists, but not uniformly with the same results. We are therefore at present unable to decide, whether the canal admitted by Bogros, does really exist before the injections which render it obvious, or whether it is merely the result of these injections. OF THE NERVOUS SYSTEM. 171 % phatics can be traced into the substance of the nerves; but their blood vessels are very numerous and penetrate the * neurilema as far as the nervous filaments. Characters, physical and chemical properties. — The cerebro-spinal nerves possess but a slight degree of elasticity, are of a faint rose colour, and owe to their neurilema the slight degree of tenacity which they enjoy. The dilute acids, especially the nitric, dissolve the neurilema, and expose the nervous pulp, while the alkaline solutions destroy it and leave the neurilema untouched; it is this knowledge of the modus operandi of the acids and alkalies upon the nerves, that has furnished Reil with the means of analysing and detecting the anatomical elements which contribute to their structure. The medullary substance of the nerves yields a greater quantity of albumen, but less of the fatty sub- stance, than the encephalo-rachidian masses. Development. — The cerebro-spinal nerves, are the first parts of the nervous system of the embryo that are brought into existence. In the foetus, they are proportionably more vascular than they are subsequently, but their struc- ture is indistinct, and their neurilemic part appears to ex- ceed the medullary, which is nothing but a mere liquid. The volume of the nerves is much greater in proportion to that of the encephalo-rachidian centre, as they are exam- ined near the period of conception. In old age, they are smaller, more dry and firm, than in adult life, at the same time that their vitality is less energetic. Vital properties and functions. — The nervous energy of the organs of which we are treating, is rendered evident by the violent pains and the muscular contractions which are occasioned by their artificial or morbid irritation. This power is inherent in the nerves, and is merely called into action by that of the medulla spinalis, and the encephalon; for, when we irritate a motor nerve, that has been sepa- rated from these centres by the knife or ligature, the mus- cles to which it is distributed are agitated with convulsive 172 OP THE NERVOUS SYSTEM. motions. Anatomists have hitherto heen unable to trace the least sign of vital contractility in the cerebro-spinal nerves. The nerves are the organs which transmit to the centre of perception, the impressions which they receive in the or- gans to which they are distributed, and carry to every part of the body the nervous power upon which depends the muscular contractility. They are thus conductors of sen- sibility and of motion by a double action, from the centre to the circumference, and from the circumference to the centre, during which they manifest neither the vibrations nor the oscillations that have been admitted by some au- thors to explain the mechanism of the functions of trans- mission. The rapidity with which they are performed has induced many to believe, that there is an imponderable fluid, analogous to that which produces the phenomena of electricity, and of which the nerves are the mere conduc- tors. Several physiological experiments give support to this hypothesis. Be this as it may, however, we ought to distinguish, amongst the en cephalo-rachidian nerves, those which are exclusively devoted to the transmission of mo- tion, or the mptor nerves; those which belong merely to the functions of the external sensations, or the sensitive nerves; and those which are at once conductors of sensi- bility and of motion, or the ?nixed nerves. The first two classes comprehend all the nerves of the head, with the exception of the fifth pair, which, together with all the spinal nerves is included under the class of mixed nerves. Magendie, however, has satisfactorily demonstrated, that even in the spinal nerves, the two orders of functions have, to a certain degree, their distinct seat; that the anterior root is destined to motion, and the posterior to sensibility.* * Mr. Charles Bell has lately .performed a great number of experiments with the view of specifying the functions of the nerves, and has obtained very important results to physiology. He divides the nerves into regu- lar and irregular: the first, which are common to all the vertebral ani- OF THE NERVOUS SYSTEM. 173 Pathological Anatomy. The nerves sometimes increase in volume, in conse- quence of serous, gelatinous, or fatty infiltrations of their tissue; they are often compressed, flattened, or displaced, from the development of tumours in the surrounding parts, and their atrophy, which sometimes depends upon the same cause, may also be the result of the cessation of their func- tions, (paralysis.) When a nerve has been divided, the two extremities, if they have been separated but a small distance, are re-united by a nervous cicatrix, and the mo- tions of the nerve, at first interrupted between the solution of continuity and the peripheral extremity, are perfectly re-established. The manner in which this re-union is ef- fected, may be comprised under the following observations. The superior extremity of the divided nerve, in conse- mals, preside over the general sensibility and voluntary motions, and comprise the spinal nerves, (including the sub-occipital,) the trifacial, or fifth encephalic pair, and all the nerves with a double root; the second are the nerves with a single root, and being connected with the preceding, in proportion as the organism is complicated, are distributed to the organs which are amply provided with the former, and preside over the special functions. Mr. Bell, having divided the branches of the facial nerve of an ass, (the portio-duro of the seventh pah' of "Willis) which are distributed to the nostrils, paralysed the muscles of the parts, but those only which are subservient to respiration, and the expression of the face: on the contrary, when he divided the superior maxillary branch of the fifth pair, the skin of the face was deprived of sensibility, and the subjacent muscles lost their contractility, with the exception of those which perform the motions of respiration and expression, whose nerves were left undivided. From these facts, and others of a similar nature, Mr. Bell concludes that the presence of several nerves in a part coming from different origins, has not for its object the accumulation of a great quantity of the nervous influence, but the performance of seve- ral distinct and peculiar functions. From these researches, we perceive also how favourable are the results to the doctrine of the plurality of the . nervous svstem. 174 OK THE NERVOUS SYSTEM. quence of the afflux of blood becoming the seat of the ex- halation of coagulating lymph, begins to swell in a short time after the division, and forms a kind of firm, elongat- ed, grayish nodule; the inferior extremity presents, in its turn, the same phenomena as the preceding; and as the tu- mefaction increases, the extremities approximate, and are finally agglutinated together, by means of the plastic sub- stance which they exhaled. The enlargement which re- sults from the junction of the two nodules remains some time; but it gradually diminishes and finally disappears. There-union is perfectly re-established in about six weeks or two months. In this process, there appears to be a re- production of the medullary part of the nerve, and several anatomists have asserted that they have even traced the medullary filaments into the interior of the cicatrix. What proves this fact is, that the cicatrix acquires the conduct- ing power of the organs of which we are treating, and that when submitted to the action of nitric acid, far from being decomposed, it assumes more consistence, as is the case under similar circumstances with the nervous substance. The restoration of the functions of a divided nerve does not take place, if the separation of the extremities be too consid- erable, and where there-union is effected merely by means of cellular substance. If, on the contrary, the separation is so inconsiderable as scarcely to be perceived, the action of transmission may take place, to a certain degree, from one part of the nerve to the other, from the moment the divi- sion has been effected. Inflammation of the nerves (neuritis) appears to be a more common disease than is generally be- lieved; it is often observed in oases of neuralgia — a disease which, however, frequently presents no appreciable alter- ation of the nervous tissue. It is in part to a sub-inflam- matory state of these organs that we must attribute their softening, and the tuberculous and schirrous tumours, de- signated collectively by the name of neuroma. To the •same cause may also be referred the cartilaginous and osse- OF THE NERVOUS SYSTEM. ous metamorphoses of the nerves — a kind of alteration, which is sometimes, though rarely observed, and is confin- ed to some insulated points of these organs. ARTICLE 2. Of the Ganglionic Nerves. Definition. — The ganglionic nerves are those which constitute, with the ganglia of the second class, the system of the great sympathetic or trisplanchnic nerve, — those, in other words, which being situated exclusively within the trunk, form with the ganglia just mentioned, a particular order of nervous apparatus, communicating with each other and with the spinal nerves by intermediate branches, and distributing numerous ramifications to the arteries and the organs of vegetative life: hence, the distinction of the nerv- ous system of organic life, given by Bichat to the assem- blage of this apparatus. Division. — The ganglionic nerves are distinguished into three varieties: the first comprehends those which form the communications between the ganglia, the second, those which are intermediate between the ganglia and the cere- brospinal nerves, and the third, those which are ramified within the organs. Situation. — The intermediate ganglionic nerves are mostly situated upon the sides of the vertebral column, parallel with its axis, and between the double series of the lateral ganglia, which extend from the head to the os coc- cygis. The others extend from the lateral to the mesian ganglia. The ramifications of the second variety are placed, most of them, transversely upon the sides of the vertebral column, between each lateral ganglion and the corresponding spinal nerve. The situation of the ramifi- cations varies in each organ to which they are distribut- 176 OP THE NERVOUS SYSTEM. ed; but, like the preceding, they belong exclusively to the trunk. Conformation. — Considered as a whole, the ganglionic nerves by no means exhibit the symmetry of those which issue from the encephalo-rachidian masses. Beclard has justly compared the system of the great sympathetic " to a subterraneous stem or articulated root (rhizome,) which, upon one side of each bulb presents small roots, and upon the other, small branches, all of which are separated at right angles, or nearly so." As to their peculiar form, the ganglionic nerves are not all alike: those of the second variety are rounded, and re- semble, in this respect, the spinal nerves: those of the other varieties are flattened, and, besides, those of the third present this peculiar character, that instead of diminishing in vo- lume in proportion as the)'' ramify, they augment or dimin- ish in different ways. All are larger in the neighbourhood of the ganglia than in the rest of their extent. Origin. — Many anatomists have disputed whether the ganglionic nerves arise from those of the cerebro-spinal system, with which, as we have already seen, they com- municate, or whether the ganglia ought to be regarded as their centres of origin. Neither of these propositions, however, is properly admissible, for the development of the ganglionic nerves is perfectly independent of that of the other parts of the nervous system; but in applying, as we have already done, to the term origin, the signification of central extremity , we ought to place it in the ganglia of the great sympathetic, and consider the nerves which pass from them to the organs, as forming with the first so many small nervous apparatus, which communicate with each other and with the encephalo-rachidian nerves. At this central extremity, the medullary filaments of the ganglion are continued with those of the nerve, and moreover, the envelope of the first being extended upon it, adds firmness to their mutual adhesion, and, bv covering the second to a OF THE NERVOUS SYSTEM. 177 small extent, gives it the appearance of a part of the gan- glion, elongated in the form of a cord. Course. — The ganglionic nerves of the first variety pass directly, and without presenting any thing peculiar, to the cerebro-spinal nerves. The same arrangement obtains with regard to the cords which form the communications between the ganglia, and especially with those, which, be- ing placed at each side of the vertebral column, form with these what is called the trunk of the great sympathetic nerve. As to the nerves which pass from the ganglia to the arteries, and to the different organs of the head and neck, and to those of the chest and the abdomen, they are ramified in their course and form more or less intricate plexuses, either before they have reached their destination, as in the cardiac and solar plexuses, or after they have ar- rived upon the parietes where they decussate with the fila- ments coming directly from the ganglia. In their course, as well as in the plexuses, these nervous filaments are con- nected with the ramifications of the encephalic nerves, and particularly with those of the pneumo-gastric. Organic extremity or termination. — The ganglionic nerves (and we speak here only of those of the third varie- ty,) terminate in the parietes of the arteries of the trunk, in the heart, the digestive canal and its appendages, and in the urinary and genital organs. Structure. — The ganglionic nerves of the first variety, and even those of the second, are formed of small medullary fibres, and of a neurilemic envelope, which is more dense at their extremities, where it is sometimes continuous with the envelope of the ganglia, more thin and delicate at their middle part, and more intimately connected with the small fibrillar than that of the cerebro-spinal nerves. These last are very difficult to be separated from each other, and are, moreover, plunged into the peculiar grayish red substance, which we have already described as # belonging to the gan- glia. Notwithstanding the differences which we have just 17S OF THE NERVOUS SYSTEM. pointed out between these nervesand those of the cerebro- spinal system, both resemble each other with regard to form, colour and structure: the branches which connect the ganglia with the spinal nerves, resemble these in par- ticular, and much more in proportion as they approach them. As to the nerves of the third variety, we can not distinguish in them any fibrillar, and they appear to be entirely formed of a soft reddish pulp, around which we can not demonstrate the existence of a neurilema. Characters and physical properties. — The nervous cords which pass from the ganglia to the cerebro-spinal nerves have a whitish appearance, are less firm and resist- ing than these, and appear to be destitute of elasticity. Those which connect the ganglia together are of a grayish colour, have more of the bulbous substance, and are some- what less tenacious and consistent than the preceding. The ganglionic nerves which are distributed to the organs are, with some very few exceptions, of a reddish colour, very soft and brittle. Vital properties and functions. — The nervous energy of the ganglionic nerves appears to be less active than that of the cerebro-spinal nerves, and this in proportion as they are more frequently intersected by the ganglia. In their healthy state, this nervous power of the ganglionic nerves is not manifested, either by sensibility or contractility; but in certain diseases, they are the seat of a peculiarly painful affection. The ganglionic nerves serve to transmit the nervous in- fluence to the organs of the involuntary functions, but they do not convey to the ©entre of perception the impressions which are received by these organs; these being, under or- dinary circumstances and unless the action of the nerves be stimulated by disease, arrested by the ganglia. All the ganglionic nerves, at least those of the first two varieties, contribute to the phenomena of sympathy, by establishing communications between the ganglionic and the cerebro- OF THE NERVOUS SYSTEM. 179 spinal system; but it is doubtful whether they are, as was asserted before the time of Bichat, the essential organs of the sympathies. All the nerves are, by reason of their con- tinuity, susceptible of producing these phenomena. The action of the nerves of which we are treating, though more independent than that of the cerebro-spinal nerves, is, how- ever, subordinate to them, inasmuch as it ceases as soon as these nerves are separated from the cerebro-spinal. The nervous influence, which is transmitted to the ganglionic nerves by the centres above mentioned, arrives in the organs only after it has been, probably, diminished, diyided and modified by the ganglia, which distribute it. It is, therefore, to this character which we attribute to the ganglia that ought to be referred the independence of the portion of the nervous system to which they appertain. Pathological Anatomy. — Few anatomists have paid attention to the study of the pathological anatomy of the ganglionic nerves. They have been known to be inflam- ed in cases of neuroses of the abdominal organs, and in subjects who have died from pertussis: they are also some- times affected with atrophia and hypertrophia, especially when the organs to which they are distributed present the same pathological conditions. Bibliography of the Nervous System. Vicq-d'Jlzyr. Recherches sur la structure du cerveau, etc, dans les Mem. de l'Acad. des Sciences, 1781-83. Traite d'Anatomie et de Physiologie, gr. in fol., avec pi. Paris, 1786. Gall et Spurzheim. Anat. et Physiologie du systeme ner- veux en general, et du cerveau en particulier. Paris* 1810-19. Fr. Tiedemann. Anatomie du cerveau, trad, de l'allem. par Jour dan. Paris, 1823. Serres. Anatom. comparee du cerveau dans les quatre ISO OF THE NERVOUS SYSTEM. classes des animaux vertebres, 2 vol. in So. avec atlas. Paris, 1824 et 1826. Desmoulins. Anatomie des systemes nerveux des animaux a vertebres, etc. Paris, 1S25. Rolando. De la veritable structure du cerveau de Phomme et des animaux, et des fonctions du systeme nerveux; trad, de l'italien et insere dans le Journal Physiol, ex- perim. torn. III. • J. et Ch. Wenzell. De penitiori structura cerebri. Tubing. 1812. H. M. Edwards. Mem. sur la struct. el6m. des principaux tissus organiques des animaux vertebres. Paris, 1823. Proschaska. De structura nervorum anat. in opera minora. Reil. Exercitationes anatomicse de structura nervorum. Halle, 1797. Pr&vost et Dumas. Mem. sur les phenomenes qui accom- pagent la contraction musculaire. (Journal de physiol. experim., torn. III.) In this memoir are contained some very interesting de- tails upon the structure of the nerves, a concise account of which will be found in a note in the third section of this chapter. Bogros. Note sur la structure des nerfs (dans la Revue medec, mai 1825, p. 237.) Haase. De gangliis nervorum. Leipsic, 1772. Scarpa. De nervor. gangliis et plexubus. Modene, 1779. Lobstein. De nervi sympathetici humani frabrica, usu et morbis. Paris, 1823, in 4o. avec pi. Bracket. Memoire sur les fonctions du Systeme nerveux ganglionnaire. Lyon, 1825, Ch. Bell. Recherches anat. et physiol. sur le systeme ner- veux (Journal de physiol. experimentale, torn. I. et II.) Bell on the Nerves. Legallois. Experiences sur le principe de la vie. Paris, 1812 OF THE NERVOUS SYSTEM. 181 Georget. De la physiologie du systeme nerveux. Paris, 1821. Breschet. Art. Acephale, et Anencephale du Dictionn. de Medecine en 18 vol. Geoffroy-St. Hilaire. Philosoph. anatom., torn. II. Pinel fils. Recherches sur Pendurcissement du systeme nerveux. Paris, 1822. Lallemand. Recherches anatomico-pathologiques sur Pen- cephale et ses dependences: quatre lettres. Paris, 1820, 1823. Rostan. Recherches sur le ramollissement du cerveux, 2e. edit. Paris, 1823. Ollivier (d'Angers). Traite de la moelle epiniere et de ses maladies. Paris, 1823. Rochoux. Recherches sur l'apoplexie. L. G. Descot. Dissertation sur les affections locales des nerfs. Paris, 1822. Magendie. Exper. sur les racinesdes nerfs qui naissent de la moelle epiniere (Journal de Physiologie experimen- tale, torn. II.) Breschet, M. Edwards et Levasseur. De Pinfluence du systeme nerveux sur la digestion stomacale (Arch, gener. deMed.,aout 1823.) Wilson Philipp. De Pinfluence du galvanisme sur la di- gestion, la respiration, etc. (Arch, gener. de Med., mai 1823.) Humboldt. Resultat d' experiences sur les actions galva- niques, etc. (Arch, gener. de Med., octobre 1823.) Flourens, Recherches experimentales sur les fonctions et les proprietes du systeme nerveux dans les animaux ver- tebres. Paris, 1824. 1S2 TEGUMENTARY SYSTEM. CHAPTER V1H. TEGUMENTARY SYSTEM. SECTION 1. General Observations. Definition. — The tegumentary system is composed of a large membrane which covers the entire surface of the body, and enters it so as to line all the cavities which com- municate with the exterior world. Division. — The tegumentary system is divided into two secondary systems, the cutaneous and the mucous. Situation. — The teguments are placed upon the surfaces of the animal which communicate more or less directly with exterior objects: thus, after having covered the whole exterior surface of the body, it lines the mouth, the oeso- phagus, the stomach, the intestines, and all the excretory ducts that empty into them, the aerial passages, the nasal fossae and all their sinuses, and the urinary and genital or- gans. General conformation. — The tegumentary system, re- presents, by its situation, all the other organs of the body, and its general form may be. compared with that which re- sults from the union of two hollow cylinders, which are continuous by their extremities and are separated at their contiguous surfaces by an intermediate substance. This comparison is applicable only to the skin and to the mu- cous membrane which extends from the mouth to the anus; TEGUMENTARY SYSTEM. 1S3 it will include, however, all the teguments, if we add to the cylinders which we have just mentioned, certain pro- longations or appendages, which are plunged in different points of the intermediate substance, and line the aerial passages, the excretory ducts of the glands, the genito- urinary organs, &c. Surfaces. — The tegumentary membrane presents two surfaces, one of which is free, the other adherent: the first, which is external to the skin, and internal to the mucous membrane, is in relation in a continuous or interrupted manner with the substances that are actually foreign to the organization. The free surface presents small granular eminences, porous depressions, and horny or calcare- ous productions, either situated together, or scattered in different points: the adherent surface, which is internal to the skin, and external to the mucous teguments, corres- ponds immediately with the layer of cellular tissue, which we described in the first chapter, and, through the medi- um of which, this surface is connected with the subjacent organs. The adherent surface has small eminences, which are more or less prominent and correspond to the depres- sions on the free surface. Structure. — In the organization of the teguments, we are to consider: 1st, the different layers of which they are composed and upon which their form depends, and 2d, their small secretory organs. The layers which form the tegumentary membrane are five in number: they vary in a very sensible manner, in the different parts of this organ, and especially, in its two grand divisions: we shall enumerate them in pointing out their most general characters. 1st. The dermis or chorion constitutes the basis of the teguments, is the thickest of the layers of which we are treating, and is situated underneath them: it is formed of compact cellular tissue, which permits numerous blood ves- sels and nerves to ramify between its fibres. 1S4 TEGUMENTARY SYSTEM. 2d. The vascular retiform layer, which is placed upon the dermis, is extremely thin and delicate, and results from the interlacement of the small arteries, veins and lympha- tics which traverse it. 3d. The small papillx, are formed by the peripheral extremities of the nerves which traverse the preceding laminae. It is probable, that the nerves of these small nerv- ous papillae, which are situated upon the surface of the teguments, belong, like most of the others, to the dermis itself; and are only invested by the extremities of the nerves which traverse it with the vessels, and terminate upon its surface. These last two laminae are not well marked, and ought to be regarded rather as the most superficial parts of the first. 4th. The rete mucosum of Malpighi consists of a layer of semi-organized mucus which contains the pigment or colouring matter of the skin, and is situated between the epidermis and the superficial laminae of the chorion. The existence of the rete muscosum, first described by Malpighi, and since by many anatomists, has been denied by Bichat and M. Chaussier; while some, and amongst others, M. Gaultier, founding their opinion upon observations on the skin of the negro, assert that it consists even of several layers. 5th. The epidermis or scarf-skin, is the most superfi- cial of the tegumentary laminae, and is by no means dis- tinct in every part of the system of which wc are treating. The epidermis, considered by some as formed of several laminas, endowed with a certain degree of vitality, which diminishes progressivel)' from the most internal to the most superficial, and by others, as having a squamous structure, is a whitish, semi-transparent, membraniform substance, which is moulded upon the prominences of the chorion, and is generally regarded in the present day as destitute of life, and as deposited upon the surface of the teguments by an excretory process. TEGUMENTARY SYSTEM. 185 The small secretory organs that are observed in thetegu- mentary system are known under the names of folliculi, cryptse, &c. and consist of a species of very small, oblong or rounded cyst, terminated by a more narrow part, — a kind of neck, which performs the office of excretory duct, and opens upon the free surface of the teguments: hence, the small porous depressions which are observed upon this surface. The follicles appear to result from a simple de- pression of the tegumentary membrane, and are formed of the same anatomical elements, that is, of a dense capsule similar to the chorion, surrounded and pervaded by nume- rous vessels; of a vascular nervous net-work spread upon the concave surface of the dermis, and of excretory parts which vary according to the kinds of follicles, and which sometimes contain a pigment or colouring matter, as that which is observed in the hairs, &c. The follicles may be divided, according to the nature of their secretions, into two kinds: the first comprehends those which secrete a more or less fluid substance, and carry it to the surface of the tegu« ments: these are the cryptae or the follicles properly so called, whose secretions vary accordingly as they belong to the skin, or to the mucous membranes. They occur in every part of the teguments; but they are not every where equally numerous. We find them sometimes in- sulated, sometimes in groups, and sometimes again in regu- lar orders. The second is composed of the follicles which are designated more particularly under the name of bulbs, and which M. de Blainville has called phaneres*, because their secretions, being always solid, remain apparent on the surface of the animal: these productions are, the hairs, the nails and the teeth. The bulbs occur only in certain parts of the tegumentary tissue, and are almost always col- lected in groups. Characters, physical and chemical properties. — The * From Qavtfor, evident, S. D. G, 25 186 TKGUiMENTARV SVSTEJM. colour of the tegumentary membrane varies accordingly as it is owing to the presence of blood or to that of pigment; there being in this respect remarkable differences not only between the external and the internal teguments, (the latter have no pigment,) but also between the different parts of the same membrane. The internal membranes also vary in regard to their density and thickness; but it may be said as a general rule, that their density is intermediate be- tween the cellular and the fibrous tissues. The teguments are susceptible of considerable extension, after which they re- cover their original dimensions, either suddenly, or slowly, accordingly as the distension has been ancient or recent, and accordingly as its cause disappears slowly or with rapidity. The elasticity, or rather the retractility of the tissue of the tegumentary membranes, is moreover rendered evi- dent by the rapid separation of the borders of the solution of continuity, at the moment of an operation. — Exposed to the action of ebullition, the chorion is almost entirely reduced to gelatine, and this principle, together with a small quantity of mucus, appears to be the principal ingredient in the composition of the reticular body of Malpighi. The epi- dermis is insoluble in water. M. Vauquelin regards it as indurated mucus; Hatchett as coagulated albumen.* At the commencement of putrefaction, the subjacent laminse to the epidermis spontaneously separate; and the epidermis it- self is detached a few days after death by the fluids which transude through the chorion. Vital j)roperties. — The teguments enjoy a very active vitality. The numerous nerves which are distributed to them render them extremely sensible, but in such a man- ner, and in such degrees, as vary greatly according to their * The human epidermis possesses the same properties as horn: it con- sists of — fatty matter, 0.5; animal matter, soluble in water, 5.0; concrete albumen, 93 to 95; lactic acid, lactate, phosphate, and hydrochlorate of potash, sulphate, and phosphate of lime, an ammoniacal salt, andiraees of iron, 1.— John Ecrits, Chim. VI, 92.— S. D. G. TEGUMENTARV SYSTEM. 187 different parts. Their vital contractility is equally remark- able. Differences according to age. — Wolff, Ocken, and Mec- kel, regarding the vitelline membrane of birds as analo- gous to the urachus of the marnmiferi, are of opinion, that the intestinal canal arises from the umbilical cord at the beginning of the human ovum, and that the tegumentary membrane of this canal exists before any of the other or- gans. According to the same manner of observing, the in- ternal tegument is formed before the external. These con- clusions are far from being satisfactory, and we possess as yet no positive information with regard to the time in which theformation of the teguments begins to take place. It would appear natural to suppose, however, that they do not pre- cede in their development the organs which they are des- tined to cover: thus, the skin, which at first forms onl}- a demi-canal, is open at its anterior surface, because the an- terior parietes of the trunk present an interruption at the same time. The skin approaches successively to the mesian line, in proportion as the parietes of the abdomen them- selves approximate, so that the interruption only ceases after these are fully united. The teguments pass succes- sively from their semi-liquid state to their proper consist- ence. Their thickness is in direct ratio with the age of the individual. The differences which exist between the external and the internal teguments, scarcely observable in the early stage of foetal life, become more prominent in proportion as the individual advances in life. Functions. — The tegumentary system envelops the en- tire mass of the body, protects it from external injuries, and establishes its relations with the exterior world: 1st, as an organ of general sensibility, and of special sensations, and 2d, as an organ of absorption, and of exhalation. The functions of this system vary in the different parts of the body — a difference which results from a difference in their organization. 188 TEGl'MENTARY SYSTEM. The extent of the tegumentary organ, and the importance of its functions render its state of integrity of the highest consequence to the general health. The intimate sympathy which exists between the different parts of the teguments, renders it necessary to the health of the individual, that there should be the most perfect anatomical and physiolo- gical integrity; thus, the suppression of the cutaneous ex- halation, is almost invariably followed by an increase of exhalation of some of the mucous membranes, and this su- perabundance of activity, or rather, the humoural conges- tion which takes place, may be followed by inflammation: such are the most frequent causes of bronchitis, pneumonia, and some other affections. section 2. Of the Skin. Definition. — The skin is that part of the tegumentary membrane which covers the whole external surface of the body. Division. — The external teguments consist of the skin and its appendages, which are, in the human subject, the nails and the hairs. — These will be described with the ap- pendages of the mucous membranes in the fourth section of the present chapter. Conformation. — The skin represents the form of the body which it covers, enters into its cavities, such as the mouth, the nostrils, the anus, the urino-genital organs, &c, and becomes mucous membrane, without interruption of continuity. The skin often presents rugas or folds which depend upon this membrane, which, not being susceptible of con- tracting as much as the subjacent tissues, becomes pucker- ed so as to accommodate itself to their retraction, and some- times, also, owing to the loss of a portion of its elasticity in TEGUMENT ARY SYSTEM. 189 consequence of age, the membrane can not retract when the organs which it covers diminish in volume and cease to sustain it. The other folds are those which are observ- ed upon the skin of the articulations, and are the result of the intermittent extension which it experiences in conse- quence of the motions of the joints. Surfaces. — The external or free surface of the skin is in relation with the exterior world. It is smooth and even, especially in the female, and is moistened by the perspira- tory and sebaceous exhalations. We observe upon the free surface of the skin, besides the folds of which we have al- ready spoken, and which extend through the entire thick- ness of the membrane, small papillary prominences, and several kinds of depressions. The prominences are either insulated, or arranged in linear order, accordingly as their direction varies; the most numerous and remarkable by the regularity of their disposition, are those in the palm of the hand and the sole of the foot. This surface also presents the orifices of the sebaceous bursse, which are more nu- merous and conspicuous in the face, especially on the wings of the nose, than any where else. Finally, the external surface of the skin presents, in cer- tain parts, the excretions of the bulbous or phaneric folli- cles, that is, the hairs and the nails. The internal or adherent surface of the skin is connected with the subjacent parts by cellular tissue, which is either loose, or very compact, accordingly as the skin is destined to perform more or less extensive gliding motions. We have already seen, in a preceding part of this work, that there are synovial capsules interposed between different organs and the tegumentary membrane to facilitate their motions. The skin is most frequently in contact with the adipose tissue; sometimes, however, it is intimately con- nected to the fibrous organs, and at others, to the suhcu- 190 TEGUMENTARY SYSTEM. taneous muscles, which are more generally found in ani- mals, and are more important in them than in man.* The internal surface of the skin presents numerous, ob- lique, areolar depressions, containing adipose tissue, and having their base pierced by small foramina, for the passage of blood vessels and nerves: these depressions, which are al- most invisible in some parts, as in the dorsal part of the hand and the foot, the scrotum, &c, are remarkably large in the palm of the hand, the sole of tbe foot, the back, the abdo- men, &c. We observe also upon this surface, numerous small prominences, or secretory organs, which are formed by the base of the follicles of this membrane, and appear, as we have already said, to result from a depression of the chorion. Structure. — We shall here enter into a more minute detail with regard to the laminae of which we treated in the preceding section. 1st. The dermis, or the principal lamina of the cutaneous organ, is formed of a peculiar cellulo-fibrous tissue, which some anatomists have supposed to be analogous to the mus- cular fibre; but it appears to result from a modification of the generative tissue, less characterized than that which constitutes this fibre. The fibrous structure of this tissue is most evident in the palm of the hand, the sole of the foot, and in those parts where the dermis is connected with a layer of the fibrous tissue: we may then regard it as the most superficial part of the fibrous tissue, from which it is almost impossible to separate it. The fibres of the dermis are indistinct on the greatest part of the trunk and the extremities, nor are they at all distinct upon the dorsum of the hand and foot, the fore- head, &c. The tissue of the dermis is less compact on its internal, than upon its external surface, where it is cover- * The platysma-myoides is the only muscle of tliis kind in the human subject. — S. D. G. TEGUMENT ARY SYSTEM. 191 ed by the vascular net-work, and presents the papillary prominences which we have just pointed out on the exter- nal surface of the skin, and which are more conspicuous upon the dermis where it is denuded of its subjacent laminae, which have a tendency to obscure them. The internal surface lies almost every where upon a layer of adipose tissue, which varies in thickness, penetrates the interstices of the dermis, and contains a great number of blood ves- sels and nerves: these insinuate themselves into the cells of the dermis, distribute filaments to its tissue, and terminate, most of them, upon its external surface, where they form by their interlacement the second layer of the skin. The dermis is generally white; when its vessels, however, ad- mit much blood, it presents a faint red colour. It is very thick on the posterior part of the trunk, the external sur- face of the extremities, the palm of the hand, and sole of the foot, upon the cranium, &c; more thin and smooth on the anterior part of the trunk, the internal surface of the extremities, the face, and still more delicate on the eye- lids, the genital organs, the nipple, &c The thickness of the dermis varies in these different parts from about a sixth to a twentieth of an inch. It is supple, extensible, and retractile. By desiccation it is rendered elastic like horn; by the action of ebullition it is resolved into gelatine:* un- der the influence of cold, of certain moral affections, &c, it exhibits true vital contractions. The papillae upon the external surface, appear to favour the tactile sensibility of the skin; at least, they are more developed where this sen- sibility is more exquisite. 2d. The vascular retiform layer is merely, as we have already said, the external surface of the dermis, and not a dis- * It is the gelatinous nature of the chorion which renders it fit for the purposes of the arts. In effect, the gelatine combines with the tanin, and forms an insoluble compound, which the tanner obtains by putting the dermis in contact with different kinds of bark (those of the oak, the fir, &c.,) which contain the principle to which we have just alluded. 192 TEGUMENTARY SYSTEM. tinct layer. Notwithstanding this, it is well developed in those parts where there is constantly a bright florid colour, as in the cheeks, and enjoys there a kind of erection, as is proved by some of the moral affections. — It is this part of the skin which is the true seat of the cutaneous exhalation and absorption. 3d. The small papillse, are also indistinct from the su- perficial part of the dermis: they are situated on the exter- nal surface of the dermis, and are in part composed of the vascular retiform layer. The sense of touch being in di- rect ratio with the number of these small prominences, it is supposed that the nervous substance is more abundant there, than in the other parts of the skin; this, however, can not be demonstrated. 4th. The rete mucosum, which has eluded the observa- tions of Bichat and Chaussier, notwithstanding the most minute dissections, is spread, as is asserted by those who have seen it, under the form of a mucous lamina, upon the preceding parts, and is moulded exactly upon the papillae. This lamina, which is the seat of the colour of the skin, is much more conspicuous in proportion as the colour is more prominent. It is generall} 7 regarded as a simple lamina, but several anatomists, and particularly M. Gaultier, assert that it consists of several layers. This physiologist, drawing his conclusions from a number of experiments performed upon the skin of the Negro, asserts that the rete mucosum con- sists of four laminae: the internal is vascular, and secretes the colouring matter of the skin; the second, placed imme- diately upon the first, is white, inorganic, and is termed albuginea 'profunda; the third is composed, like the first, of small arteries and veins united in clusters, and is im- pregnated with the colouring.matter of the skin; the fourth, or the albuginea super Jicialis, is inorganic like the second, is secreted by the third, and covered by the epidermis. M. Dutrochet admits the existence of the last three of these laminae, and regards the first as identical with the vascular TEGUMENT ARY SYSTEM. 193 retiform layer on the surface of the dermis. Be this, however, as it may, the colouring matter of the skin, lo- cated by many anatomists in the dermis, and especially in the epidermis, is really intermediate to these two laminae, without their being, however, completely foreign to it. This matter, called pigmentum nigrum, is disseminated throughout the rete mucosum under the form of globules: it may be separated by long maceration, which, in dissolv- ing the semi-organized mucus in which it is plunged, separates it without alteration. These experiments have been made only upon the skin of the negro:* that of the European, contains but little of the pigmentum nigrum; and in the Albinoes, it is entirely wanting. The thickness and consistence of the rete mucosum are in direct ratio with the quantity of this matter: it is almost entirely composed of carbon, and appears to be of use in defending the ex- ternal teguments fror/i the rubific action of caloric, by ab- sorbing its rays, and preventing them from entering the small papillae: the Albinoes, therefore, are very sensible to the impressions of the solar rays, even sometimes to such a degree as to produce the vesication of their skin. 5th. The epidermis, the most superficial laminse of the skin, is a very delicate membranous layer, which is per- fectly moulded upon the preceding, and adheres to them intimately, first, by the hairs which traverse it; and which it furnishes with a cortical expansion; and secondly, by the small filaments which are perceived between the epider- mis and the chorion, after they have been detached by pu- trefaction, or by immersion in boiling water. These fila- ments have been hypothetically regarded by some anato- * In the negro, the rete mucosum may be deprived of its black pig- ment, by immersing' the foot or hand for some time in water impregnat- ed with chlorine gas: in a few days, however, the original colour will re- turn with all its former intensity. This experiment was first made by Dr. t3eddoes, and has since been repeated by many physiologists. S. D. G. 26 194 TEGUMENTARY SYSTEM. mists as exhalent and absorbent vessels. Beclard has just- ly thought that we might consider them as mucous tractus, formed by the intermediate substance between the chorion and the epidermis, and rendered more fluid by the incipient stage of decomposition. The epidermis covers the entire surface of the skin, like a kind of dry varnish, and penetrates, by becoming more thin and delicate, into the sebaceous and phaneric follicles. The structure of the epidermis has been a cause of much dispute amongst anatomists. While some, as M. Mo- zou, of Turin, Mascagni, Gaultier, and others, have attri- buted to it a more or less intricate organization; others have supposed that it is composed of scales, which are arranged so as to overlap each other; but neither of these opinions, however, appears to be well founded. M. de Humboldt, who examined the epidermis with a very powerful microscope, was neither able to detect the vessels of which some phy- siologists have asserted it was formed, nor the least appear- ance of organization. The epidermis appears to be a con- crete substance exhaled upon the surface of the rete muco- sum, or, if we wish, the most external part of it. Is the epidermis porous? This we might at first sight be induced to believe, by looking at the drops of sweat which are discharged from certain points of this layer, and which are depressed so as to assume the appearance of perfora- tions, and which are, moreover, much more transparent than the parts which separate them, if a portion of epider- mis be placed between the eye and the light. Leuwenhceck believed in the existence of these perforations; Bichat thought that they were oblique, and that in consequence of this only they were imperceptible; but repeated obser- vations, and amongst others, those of M. de Humboldt, do not justify this opinion; nor can there beany pores dis- covered either by inspection or direct experiments, and the epidermis appears only to be more thin and delicate in the points to which we have just alluded than any where TEGUMENT ARY SYSTEM. 195 else. Besides this difference of thickness, common to the epidermis on every part of the surface of the body, we shall find that there are others, if we compare this layer in the different regions; thus, it is more thick in the palm of the hand, and especially in the sole of the foot, — a difference which ought not to be attributed exclusively to the con- stant pressure which these parts experience, because it ex- ists already, though in an inferior degree, in the foetus. Wherever the epidermis is very thick and firm, it appears to be composed of several laminae: it is white in the Eu- ropean, grayish in the Negro, semi-transparent, supple, and less elastic than the chorion, and this in direct ratio to the humidity which penetrates it. The epidermis is faintly hygrometric, and by immersing it in water, it be- comes opake and thickened, — changes which take place more rapidly when this fluid is hot. It resists, for a long time, the putrefactive process, and completely the action of ebullition: by treating it with the nitric acid, it becomes yellow, and is afterwards reduced to a pulpy substance; and by exposing it to the action of the salts of potash and soda, it is converted into saponaceous compounds. These chemi- cal characters have induced anatomists to regard it as an al- buminous substance. The epidermis is completely destitute of vitality, and enjoys a mere mechanical character in the organization, in diminishing, by its interposition between the dermis and surrounding bodies, the impressions of these upon the nervous part of the skin. Notwithstanding its feeble hygrometricity, the epidermis gives passage to the perspiratory fluids, and allows, to a certain extent, foreign substances, either liquid or gaseous, to enter the system. The skin is supplied with a great number of sebaceous and bulbous follicles: we shall speak of the latter when treat- ing of the solid parts which they produce. As to the first, we do not know whether they are spread throughout the whole extent of the skin: be this, however, as it may, they occur in great number on the face, around the alae nasi, in 19G TEGUMENTARV SYSTEM. the groins and axilla?, around the anus and on the most hairy parts of the body. The sebaceous follicles are, as we have already said, very small vesicles which open on the surface of the skin, are destitute of epidermis, and ap- pear to result from the simple depressions of this mem- brane. They secrete an unctuous substance, which often accumulates, becomes inspissated, and may be discharged by pressure, under the form of small worms: in the meatus auditorius externus this fluid is termed cerumen.* This unctuous fluid protects the skin from the action of the fluids applied upon its surface, and performs, in this respect, the same character as the epidermis. Characters, physical and chemical properties. — The different lamina? which compose the skin, constitute, by their union, a membrane whose colour varies according to the different races of the human family, from white to black, passing through all the intermediate grades; being supple, elastic, more thick in people of colour than in the European, and being with difficulty penetrated by the fluids which are in contact with its free surface, and composed in great measure of gelatine and a certain quantity of albu- minous mucus. Vital properties. — The skin enjoys an exquisite sensi- bility, which is owing to the great number of nerves which are spread upon the external surface of the dermis, and is more conspicuous in those parts where the papilla? are very numerous, and, caeteris paribus, in those where the epidermis and the rete mueosum are thinner than in the other parts. The external tegument is susceptible of very sensible vital contractions, which give it the peculiar ap- pearance vulgarly known by the name of wrinkles. Differences according to age and sex. — The skin is not * According- to Vauquelin, the cerumen cf the ear is composed of the following 1 ingredients: 1st, albumen; 2d, an inspissated oil; 3d, a colour- ing' matter; 4th, soda; 5th, phosphate of lime. — F„ourcroy, ix. 373. S. D. G. TEGUMENT ARY SYSTEM. 197 distinct until about the end of the second month of pregnan- cy, at which period the epidermis is already visible. At first the skin is destitute of colour, and of such tenuity as to render it perfectly transparent, but it soon assumes the faint red colour which it exhibits at birth. The sebaceous cryptae appear at half the term of uterine life; during the whole period of which, the external surface of the skin, being in contact with the amniotic fluid, is covered by an unctuous layer. As we advance in age, the skin, which at birth is nearly of the same colour in all the different races, assumes the characteristic and distinctive colour of each. The colour of the skin is first observed on the genital or- gans, around the nipple, the eyes, the nails, and finally, at the end of the first week, it extends over the whole body. This membrane, which is very delicate and smooth in the infant, becomes more thick and consistent as the individual advances in life. In the male, it becomes dry, and loses its retractility with age; while, in the female, it retains almost entirely the delicacy and smoothness which it possessed in infancy. Functions. — The skin is the organ of the tactile sensa- tions and of touch. It exhales two kinds of fluid, which are eliminated by its free surface; the one is the sebaceous fluid which we have already described; the other is more thin and is continually discharged under the form of va- pour, and sometimes under that of fluid, constituting what is termed sweat: this fluid is probably discharged through the points of the^epidermis, which, in consequence of their thinness, have been considered by some physiologists as pores. The cutaneous vapour or insensible perspiration is remarkably abundant, and is, in this respect, to the pul- monary transpiration, as eleven to seven: it contains car- bonic acid gas and an odorous animal principle. When it becomes too abundant to evaporate on the surface of the skin, and is presented under the form of small drops, its composition appears to be somewhat different and more 198 TEQTTMENTARY SYSTEM. complex.* According to the analysis of M. Berzelius, sweat is composed of the hydrochlorate of potash and soda, of the lactic acid, the tartrate of soda, and a small proportion of animal matter. The sweat emits a peculiar odour which differs in different individuals, and is stronger in infancy than at any other period. There are some facts which would induce us to believe that the subcutaneous fat is also exhaled by traversing the skin, if not constantly, at least when the temperature of the body is considerably elevated. The skin absorbs, but slowly and in small quantities, the fluids which are put in contact with it; so that it is impro- per to regard it as an important organ of absorption. The small degree of permeability of the epidermis presents an obstacle to this function, which is exceedingly active when the epidermis is removed. In man, the skin can scarcely be considered as an organ of defence; though it performs this function by means of its epidermic layer, the hairs and the nails. Pathological Anatomy. When the skin suffers considerable and long continued distention, as happens during pregnancy, the fibres of the dermis are not only elongated and separated, but some of them are actually torn. When the membrane recovers its original state, these fibres cicatrize: hence the white strias which are constantly found on the skin of the abdomen of women who have had children. Another effect of distention is the production of folds and wrinkles, which vary in size according to the degree of elasticity of the skin, and conse- quently, also, according to the age of the individual. * Perspiration, whether sensible or insensible, is a very important means of depuration, the suppression of which produces some of the most fatal diseases. It has for its object the equilibrium of the tempe- rature of the body, by carrying off the superabundance of caloric which protects the system: so that those persons who perspire but little are more frequently affected with head-aches than others. TEGUMENTARY SYSTEM. I#9 The free surface of the teguments often presents different kinds of growths, which vary both in volume and form. They are generally termed warts, and are most frequently seated in the dermis, of which they are merely an unnatu- ral development: the secondary syphilitic affections ap- pear rather to be seated in the vascular retiform lamina, than in any other part of the dermis. The horny produc- tions of the skin, of which there are several varieties, are sometimes met on the tissue of the subcutaneous cicatrices: they have also been known to arise from the sebaceous follicles; but the most common are those, which, in con- sequence of continual pressure, are formed in the epider- mis, or rather they are a preternatural development and harding of the epidermis. In this manner are corns pro- duced, which are small, hard, rounded, horny elevations, and which, being placed at first on the surface of the der- mis, create the most severe pain by compressing the vascu- lo-nervous layer, sinking often in its thickness and even in the subjacent tissues. When the sebaceous matter collects merely in small quantities, the excretory ducts of the folli- cles of this name present a black appearance, and the mat- ter may be readily discharged by means of pressure. When the accumulation becomes more considerable, the orifice of the follicles still remains open, and the small tumour which results is termed a pimple; but if it enlarges, and the ori- fice becomes obliterated, the pimple forms one of the kinds of wen known under the names of meliceres, steatoma, and atheroma, names which refer to a single disease, and are merely expressive of the nature and consistence of the matter which the wen contains, and accordingly as it may be compared to honey, suet, or a kind of soft pultacious substance. In protracted diseases accompanied with marasmus, the skin appears to participate in the general decay, and pre- sents a remarkable rugoseness, a disagreeable sallow aspect, which is very common in phthisical persons. It also, some- 200 TEGUMENTAKY SYSTEM. times, appears to be affected with a kind of local hypertro- phia, in consequence of prolonged irritation. The solutions of continuity of the skin are re-united either immediately in consequence of the effusion of co- agulating lymph, or by the formation of a new tegumenta- . ry membrane on the denuded surface. When a portion of skin has been removed, the cellular tissue becomes the seat of the cicatrization, the whole process of which may be ob- served to take place in the same manner as we have describ- ed in the first chapter. When the cicatrization is completed, the skin is replaced by a tissue sufficiently analogous to its own, but which differs, however, in some respects, and is always readily distinguished. In effect, this tissue is more dense, and less vascular than the original; has generally no papillae, though its external surface, which is ordinarily smooth and polished, presents, sometimes, honeycomb-like (ganfries) inequalities. As to the colour of the cicatrices, it is more pale than that of the skin in the European; but in the negro it is at first of a white reddish colour, and gra- dually converges into that of the neighbouring teguments which it is finally confounded. When the epidermis alone has been removed, it is speedi- ly reproduced, unless the subjacent laminae are so much irritated as to suppurate, a circumstance which materially retards the formation of the new epidermis, and may even modify it in such a manner as to give it the appearance of a new tegument. Inflammation of the skin assumes a variety of forms, according to the part in which it is seated; its intensity, its cause, the nature of its secretion, 6cc. Hitherto, physicians have paid but little attention to the study of the anatomi- cal characters of the cutaneous phlegmasia^; their exterior forms have almost alone been observed; and it is after these and an often hypothetical etiology, that they have ■fied this order of diseases. It is on this account, there- TEGUMENTARY SYSTEM. 201 fore, that we possess no satisfactory information with re- gard to their true pathological anatomy. The erythematous inflammations of the skin,* that is, those which constitute erysipelas, the irruptions of scarla- tina, the first stages of a burn, the action of rubefacients and of vesicatories, are characterized by a vascular injec- tion, which affects either the superficial laminae, or the en- tire thickness of the skin, and remains evident during life by its bright red and sometimes purple colour, and by the uncircumscribed swelling of the affected organ. When the inflammation is slight, the redness disappears upon pressure, and returns as soon as the cause is removed; the disease is dispersed, and the epidermis falls off in furfura- ceous scales; or, if the patient dies in consequence of other accidents, there is not the least discoverable trace of phlegmasia. When, however, the disease is more intense, the dermis, (and chiefly its most superficial parts) is pene- trated by a great quantity of blood, becomes swollen and bright, and exhales a yellowish serous fluid, or pus, accord- ing as the inflammatory state is more or less intense or protracted. It is this which is observed especially in the cutaneous inflammations brought on by vesicatory medica- ments; the first effect of the inflammation which they occa- sion is the secretion of serum, which raises the epidermis; hence, phlyctaenae and blisters. The epidermis breaks spontaneously or artificially, falls off in shreds, and ex- poses the inflamed dermis, whose secretion now becomes purulent. In cases where the inflammation is intense or protracted, it leaves traces after the death of the individual, that is, the dermis is more or less injected, thickened and indurated in the dead body, and is sometimes penetrated, and as it were combined with the blood which fills its vessels: in certain cases, the cells of the dermis are filled with a gelatinous fluid, and its most internal ones are deprived of * From tpiQtftx, ruber. 27 202 TEGUMENTARY SYSTEM. the fat which the}' contained, by the intensity of the in- flammation. Finally, the subjacent cellular tissue becomes generally cedematous, and sometimes even inflamed and penetrated by a purulent fluid (phlegmonous erysipelas). The cutaneous inflammations often terminate in gangrene, especially when they have been very intense or brought on by aseptic cause: in this case the surface of the affected skin presents a livid or purple colour, and is surrounded by a yellowish tint; it is now covered by pblyctsenae, and after these have broken, the denuded dermis exhibits small gangrenous spots, which invade, in the course of a few hours, a more or less considerable extent of the affect- ed part, and even of the subjacent tissues. Scarifications of the skin, performed with the view of discharging exces- sive cedematous infiltrations, very readily and frequently bring on gangrene.* We ought also to refer to the gangrenous inflamma- tions of the skin, the disease called authrax, a circumscrib- ed inflammation, which is owing to a peculiar contagious agent, and is characterized by the presence of a hard, red- dish, homogeneous, gangrenous eschar, situated in the thickness of the skin, and having a tendency to extend by invading the adjacent tissues. The skin of the part affect- ed is livid, cedematous, and has a number of small blisters upon its surface, which contain a kind of sanious fluid. Furunculi are also, according to the common opinion, a cutaneous gangrenous inflammation, characterized by the presence of a whitish eschar termed the ventriculns furun- culi, (bourbillon) which is situated in the dermis, or even in the subcutaneous cellular tissue, and results from the * It appears, according - to the observations of M. Andral, Jr., that venous congestion of the dermoid tissue is sufficient to bring- on gan- grene, when the skin is very slightly inflamed, or even when it exhibits not the least sign of phlegmasia, as was observed by this author in some diseases of the heart where the difficulty of the venous circulation was excessive. TEGUMENTARY SYSTEM. 203 mortification of a portion of skin or of the cellular tissue, which has heen strangulated in consequence of the inflam- mation and swelling of the surrounding parts. — It seems difficult to admit the gangrenous nature and strangulation of the ventriculus furunculi; for as M. Gendrin observes, it does not present the characters of the eschars of the cel- lular tissue, and it occurs, moreover, when the inflammation and swelling are so slight, as to be unable to occasion the pretended strangulation to which we have just alluded. It is more probable that the ventriculus of furunculi and of authrax, results from a peculiar secretion, which is de- posited into the areolae of the dermis. The skin is often affected with peculiar acute inflamma- tions, which are characterized by the development of more or less numerous pustules, and are chiefly confined to the different kinds of variola, vaccina, and rubeola. The pustules of the genuine variola occupy the thickness of the dermis, which is of a red colour around their circum- ference, and is sometimes infiltrated with serum: during their stage of development, they present a flattened um- bilical form, and an areolar spongy disposition. If the pustules now become dry and detached, they generally leave no trace of a cicatrix, or at all events it is small and superficial, as in the distinct variet} 7- of small-pox, where the pustules are insulated and not very numerous. When the pustules, however, pass to the suppurative stage, their base is converted into a small ulcer which leaves a depress- ed reddish cicatrix, which is more red at first, but finally becomes more pale than the surrounding teguments: this forms the confluent variety of small-pox in which the pus- tules are exceedingly numerous and approach each other, and finally coalesce; the skin is swollen, often cedematous, and presents sometimes gangrenous points. Before the pustules of small-pox suppurate, they contain a limpid se- rous fluid, which by degrees becomes more thick and as- sumes a whitish appearance. This disease may be com- 201 TEGUMENTARY SYSTEM. municated by inoculation. When the pustules are conical or flattened, are situated merely upon the superficies of the dermis, and leave no cicatrices, they constitute the pseudo- variolic or varicellic eruptions, and the varioloid or modi- fied small-pox of vaccinated subjects, and of those who have had the genuine variola. Inoculation with vaccine matter by means of a lancet in- troduced under the epidermis, is followed by the develop- ment of a round pustule, sunk within the epidermis, pro- jecting upon the surface of the skin, depressed in its cen- tre, and surrounded by a red areola. This pustule contains a limpid serous fluid, disseminated through small cells which are separated by radiating and concentric septa. After a certain length of time it dries, is converted into a crust, and retains its circular and umbilical form; when it falls off it leaves a superficial and dotted cicatrix, which is more red at first, but gradually becomes whiter than the surrounding skin. When the vaccine matter has been bad, the puncture is followed by the development of a simple vesicle, destitute of an areola, having a small tubercular eminence, and disappearing without a trace of the punc- ture. In subjects that have been vaccinated, the vaccine inoculation frequently produces pustules, which differ merely from the true pustules by their situation upon the surface of the dermis; the fluid which they contain being proper for vaccination. In rubeola, the vascular retiform lamina of the dermis, presents a phlogose appearance around the pustules, which are very small and sensible to the touch. The different species of herpes all arise from chronic cu- taneous inflammation. They vary in form, and most of them appear to have their seat in the superficial or epider- mic laminse of the skin. M. Gendrin is of opinion that they originate in the sebaceous follicles. — The different kinds of tinea appear also to attack at first, the superficies of the skin, and to be propagated by degrees to the thick- TEGUMENT ARY SYSTEM. 205 ness of this membrane. It has long been known to physi- cians that the tinea favosa has its seat in the sebaceous follicles and the bulbs of the hair. The skin is susceptible of undergoing fibrous and cartilaginous transformations; of the excessive development of the retiform lamina, giv- ing rise to certain congenital stains (nsevi,) which are of a red or purple colour, and of an alteration of the pigmen- tum nigrum. In those persons termed Albinoes the pig- ment is entirely wanting, in consequence of which the skin presents a whiter appearance than naturally, with a slight shade of red, owing to the presence of blood. section 3. Of the Mucous Membranes. Synonyma: Glandulous membranes, internal membrane of the intestinal canal, of the nasal fossae, Sec, pituitary membrane of the nasal fossae, villous membrane, villoso-papillary membrane, &c, in the digestive apparatus. Definition. — Under the generic name of mucous mem- branes are comprehended all those parts of the tegumentary system, which being continuous with the skin, dip into the interior parts of the body and line all the cavities which communicate with the exterior world. Division. — The internal tegumentary system consists of two non-continuous parts, the g astro-pulmonary and the genito -urinary. Situation and arrangement. — The gastro-pulmonary mucous membrane lines the mouth, where it is continuous with the skin of the lips, and successively the pharynx, the oesophagus, the stomach and intestines at the extremity of which it is again continuous with the skin: during this course the gastro-mucous membrane sends different pro- longations to the excretory ducts of the glands which communicate with the intestinal canal. In the fauces, 206 TEGUMENTAHF SYSTEM. the gastro-pulmonary membrane sends prolongations, un- der the name of the pituitary membrane,* to the nasal fossas and their sinuses, presenting an exterior communica- tion on the margin of the nostrils where it meets the skin, penetrating superiorly into the nasal canal, lining a part of the globe of the eye and the internal surface of the eye- lids, at the free margins of which it gives place to the skin: in the posterior part of the mouth it enters the Eustachian tube, lines the cavity of the tympanum and the mastoidean cells; in the inferior part of the pharynx it dips into the larynx, the trachea, the bronchia and all their ramifica- tions. The genito-urinary mucous membrane of the male sub- ject, begins at the corona of the glans penis, enters the urethra, lines the internal surface of the bladder, the ureters, the infundibula, and even the calices of the kidneys. In the female it commences at the internal surface of the labia pudendi, and, after having lined the clitoris and the vulva, it sends prolongations into the urinary passages, which it lines in the same manner as in the male, invests the vagina, extending as far as the cervix uteri, is reflected upon its external surface, but is so indistinct in the cavity of this organ that its existence is dubious.t • Also called the Sckneiderian membrane, in honour of Professor Schneider, a German anatomist, Mho published about the middle of the seventh century. S. D. G. •j- The opinion of the non existence of the mucous membrane in the cavity of the uterus, entertained by some anatomists, has no doubt arisen from the fact that this membrane, in lining' the uterus, becomes exceed- ingly soft, delicate and vascular. At the cervix uteri it is tucked up in the form of transverse rugse, which have sometimes been described as being disposed in a foliated direction, and, in the cavity of the womb, there are a few smaller rugre, arranged longitudinally, in respect to the body of the uterus. Between these rugs there are several follicles which secrete a mucous fluid. From the cavity of the womb, the mu- cous membrane extends to the fallopian tubes, invests them completely, TEGUMENTARY SYSTEM. 207 Conformation. — The form of the mucous membranes, like that of the whole system to which they belong, results from the conformation of the parts which they cover. Nevertheless, this form is modified by the numerous folds which are presented by this membrane in several parts of its extent. The largest of these folds form true valves, composed of two laminae, contiguous at their adherent sur- face, and containing between them cellular tissue, blood- vessels, and muscular fibres, as in the velum pendulum palati and the ilio-ccecal valve. Many of these duplicatures occur on the internal surface of the small intestines, but they are much smaller than the preceding, and are known under the name of valvulse conniventes. Finally, these duplicatures occur on the internal teguments in the form of simple rugse, which add to the size of the organ which they cover: in the stomach they are distinguished by their volume; in the vagina, by their regularity. Surfaces. — The mucous membrane presents two sur- faces, one of which is free, the other adherent; the first presents small inequalities, formed, some by the small pa- pillary eminences and villi, others by the small depres- sions which constitute the mucous and phaneric follicles. The papillae are small conical eminences, which are con- spicuous only in some parts of the mucous membranes, and particularly on the superior surface of the tongue, on the corona of the glans penis, and the clitoris; they are formed of all the laminae of the mucous membranes. The villi belong probably exclusively to the gastro-intestinal membrane, and are particularly conspicuous in the stomach, the duodenum, and the jejunum. They consist of small foliaceous eminences, varying in form, and being generally larger at their free extremity than at their point of inser- tion, and formed by the entire thickness of the membrane, on the surface of which they unite and present a velvety ap- and projects, according 1 to some anatomists, beyond their broad extre- mities so as to form their fimbriated processes. S. D. G. 20S TEGUMENTAL SYSTEM. pearancc. These small prolongations are short and large in the stomach and duodenum; long and narrow in the jejunum and the commencement of the ilion: they are dis- posed in nearly parallel lines. Some anatomists are of opinion, that the free extremities of the villi are provided with small orifices, which, according to them, are the open mouths of the capillary vessels. The follicular depressions, which are ohserved on the free surface of the mucous mem- branes, consist either of simple porous orifices or of small lacunae; but, besides these follicles, there are others, which, though unimportant in the human subject and only observ- able in his alimentary canal, with the aid of the microscope, are very well developed in the second stomach of rumina- ting animals, where they constitute the large cells and al- veoli of the mucous membrane. The adherent surface of the mucous membranes presents numerous small eminences, which are formed by their folli- cular depressions, and is firmly united with the sub-mucous layer of the cellular tissue, to which we alluded in the first chapter. This layer, which forms one of the tunics of the hollow organs, and which has been improperly termed the nervous coat, gives attachment to the fibres of their muscular tunics, adheres sometimes to the periosteum or the perichondrium, and in some instances, as in the aerial passages, to the fibrous or fibro-cartilaginous organs. In these cases, the adhesion is generally so intimate that it is often impossible to separate the mucous membranes from the subjacent parts: hence, the name of the fibro-mucous membranes. The adherent surface of the mucous mem- branes is in relation with a great number of vessels and nerves, and, we have already seen, that in the duplicatures which they form, the external surface is contiguous to it- self, and has interposed between its two laminae, a layer of cellular substance, and sometimes a plane of muscular fibres. Structure. — There are not only great differences in the TEGUMENTARY SYSTEM. 209 organization of the external and of the internal teguments, but also in the different parts of the latter. Thus, the mu- cous membranes do not by any means, and in a very evi- i dent manner, present all the laminse which enter into the composition of the skin; and besides, the number of lami- nse which it is possible to distinguish in them, is not the same in the different parts of these membranes, nor are their anatomical characters everywhere alike. In regard to their organization, it is to be observed, that the mucous mem- branes do not present a distinct retiform body, and that we can distinguish in their composition only two layers, the chorion and the epidermis. Under the second point of view we may observe, that the epidermic layer, which is here known under the name of epithelium, is only appre- ciable in certain parts of the mucous membranes, viz. from the mouth to the cardaic orifice of the stomach, from the vulva to the cervix uteri, and generally, to a certain ex- tent, in those parts where the mucous membranes are con- tinuous with the skin. As to the differences which exist between the two laminse composing the internal tegu- ments, and the layers which correspond to those of the skin, the following description will suffice to give an idea. The chorion, or mucous dermis, alone constitutes the mucous membranes of the mastoidean and frontal sinuses, the conjunctiva of the eye, of all the excretory ducts, of the stomach and intestinal canal, and of the whole uri- nary apparatus, except in the neighbourhood of the ex- ternal orifice of the urethra. The chorion is presented under the appearance of a soft, spongy substance, appa- rently destitute of texture, except in the neighbourhood of the skin; the layer which it forms is generally much thinner and denser in proportion as it recedes from the skin, being remarkably tenuous and delicate in the pro- longations which line the excretory ducts. The mucous dermis is extremely vascular, and its vascularity is in di- rect ratio with the number of the different follicles, the 28 210 TEGUMENT ARY SYSTEM. papillae and villi which it presents in the different organs. As to the nerves of this layer, they can only be traced to certain parts of its extent, as to the papillae, the pituitary membrane, &c. The papillae of the mucous dermis are « formed of the capillary vessels and nerves which are upon its surface, and are defended by cellular tissue: the dispo- sition of the capillary veins of these small eminences is such as to render them erectile, a property which is very conspicuous in the papillae of the tongue during degusta- tion.* The villi are composed of lymphatic and sanguine- ous capillaries, which project upon the free surface of the mucous dermis, and are accompanied and protected, like the papillae, by cellular substance. The epidermis of the mucous membranes is, as we have already said, found only in certain parts of the internal tegumentary system. Wherever it does not exist, and par- ticularly upon the villi of the intestines, there is a layer of diffluent substance which covers the chorion, and appears to fulfil the office of the epidermis, which itself is perhaps nothing more than this substance in a state of desiccation. In other respects, the epidermis, which is more thick where it covers the papillae, and especially upon the tongue, than anywhere else, becomes gradually more and more thin and delicate as it recedes from the skin. The mucous follicles or glandulas mucipersn are form- ed, like those of the skin, by the depression of the inter- nal tegument: they consist of very small cysts with a nar- row neck, and open upon the free surface of the mucous membrane by a funnel-like orifice. They are generally found in every part of the mucous system; but on account of their volume they can not be every where readily per- ceived: they occur either separately or in clusters, and * Between the dermis and the epidermis of the lingual papillae, there is a kind of diffluent substance, which is probably analogous to the rete mucosum of Malpighi. It is destitute of the pigmentum nigrum. TEGUMENTARY SYSTEM. 211 where this is the case, they open separately upon the sur- face of the mucous membrane, or they terminate in one or more small cavities, which are commonly called lacunas, and which perform the office of excretory ducts: the amyg- dalae are nothing but a mere cluster of follicles, and the same obtains, with regard to the glands of Cowper, the pros- tate, and the caruncula lacrymalis. In the fossa navicu- lars of the urethra, the base of the tongue, &c, they are smaller and less numerous, and the lacunas upon which they border are sufficiently well developed. The mucous follicles receive numerous blood-vessels and nerves, and wherever the epidermis exists, it penetrates into their ex- cretory ducts. Characters, physical and chemical properties. — The colour of the mucous membranes varies from a beautiful red to a faint rose or grayish. The former generally occurs in the neighbourhood of the skin, particularly on the lips, the tongue, the fauces, the internal surface of the eye-lids, the glans penis, the vulva, &c; the latter is found in the greatest part of the teguments of the alimentary canal of the genito-urinary apparatus, &c. The mucous membranes which are in relation with the bile, commonly receive a yellowish tint, which is more conspicuous after death than during life, on account of the greater activity of the imbi- bition of the fluids in the dead body. The thickness and density of the mucous membranes are extremely variable; they are generally at their maximum in the neighbour- hood of the skin, (if we except the conjunctiva, which is exceedingly delicate,) and, in proportion as they recede from this, they become gradually thinner: the mucous mem- branes of the minute ramifications of the bronchia, of most of the excretory ducts of the glands, and of the frontal and maxillary sinuses, are at the minimum of the two charac- ters to which we have just alluded. In general, the inter- nal teguments are of a soft, spongy consistence, have but little tenacity, but a great degree of hygrometricity, 212 TEGUMENTARY SVSTEM. They are essentially gelatinous, and when exposed to pu- trefaction, they yield readily to its action. By the con- centrated sulphuric acid, they may be converted into a soft, pulpy mass; while the nitric acid imparts to them a yellowish orange colour before it dissolves them, especial- ly to those of the lips, of the pharynx and the oesophagus. This is an important character to be known, because it con- stitutes one of the signs of poisoning by this fluid, though it produces the same effects in the other organic solids of the body. Vital properties. — The mucous membranes are slightly contractile; and although they are generally sensible, this property is obscure in the greatest part of their extent; it is more remarkable in the neighbourhood of the external teguments, particularly in the mucous membranes of the mouth and nasal fossae, which are supplied with the nerves of taste and of smell, and in the tegumentary membranes of the glans penis and of the vulva. Differences according to age. — In the foetus, the mu- cous membranes are extremely thin and soft, and their pa- pillae are indistinct; their adhesion to the subjacent parts is readily broken, and their colour is rather violaceous than red. The mucous membrane of the intestinal canal, at the same time, contains a brownish matter, which resembles the juice of the poppy, and is hence called meconium. After birth, the internal teguments retain for a long time, their softness and delicac)\ They are generally of a faint reddish colour, which is more distinct in infancy and youth than at any other period. In adult age, they gradu- ally lose their reddish appearance and become grayish: in old age, they become more dense, and lose their vel- vety character. Functions. — The mucous membranes are organs of ab- sorption, a function which they enjoy in a very high de- gree, in consequence of the softness and delicacy of the epidermis, and on account of the absence of this lamina in TEGUMENTARY SYSTEM. 213 the greater part of their extent'. In the digestive canal, this function is rendered extremely vigorous by the pre- sence of the small vascular papillae. The mucous membranes are also organs of serous and mucous secretions: the latter of which belongs chiefly to the mucous follicles. The mucous fluids vary in the dif- ferent parts of the internal tegument, though they every where contain animal mucus, which forms their basis.* Some of the mucous membranes are the seat of particu- lar sensorial impressions, by virtue of the nerves which they receive; thus, the sensation of hunger is referred to the mucous membrane of the stomach, that of taste to the mucous membrane of the mouth, and especially to the pa- pillae on the surface of the tongue, and that of smell to the mucous membrances of the nasal fossse. There is also a very remarkable connexion between the mucous membranes and the skin, the circulatory centre, the nervous system, &c. Pathological Jlnatomy. The mucous membranes participate in the congenital or acquired mal-conformations, as well as in the displacements of the organs which they cover: they are also subject to peculiar deformities, as in cases of hernia. . When a mucous canal ceases to be traversed by the fluids to which it gives passage, it undergoes a more or less con- siderable contraction: on the contrary, however, when the fluids are more abundant than usual, the mucous mem- brane becomes much dilated, and recovers but slowly its primary dimensions after the cause of its distention has ceased to act. Inflammation of the mucous membranes is a very fre- quent and often a very troublesome disease. It is general- ly characterized by a coloration which varies from a rose * It is impossible to give a correct anafysis of these fluids, on account of their being- more or less mixed with the other secretions, such as the lacrymal fluid, the saliva, the bile, the pancreatic fluid and the urine. 214 TEGUMENTARY SYSTEM. to a deep brown, and is presented either under an arbores- cent form, or under that of small red points disseminated over a pale or reddish base, (as when the villi alone are in- flamed,) or again under that of regular uniform spots, which are most frequently of a red colour, sometimes violaceous or livid, and sometimes again argillaceous or brownish.* Besides its change of colour, the mucous membrane aug- ments in thickness at the same time that it loses its re- sistance, becomes more soft, and is easily detached from the subjacent tissues. Its secretion, which is more active at the beginning of the inflammatory stage, furnishes a kind of viscid fluid, which is more or less puriform, but often only more abundant or serous than natural; when, however, the inflammation has attained its height of intensity, the mucous secretion is completely suspended until it begins to decline: the secretion now becomes often puriform, and even purulent, without there being any ulceration of the part affected; at other times, however, the inflamed mucous membranes secrete a substance which is deposited and in- spissated upon their free surface, under the form of false membranes. — The presence of similar productions in the larynx characterizes the species of laryngitis known under the name of croup. Pseudo-membranes are also formed in certain cases of angina pharyngea and trachialis, in some of the phlegmasise of the mucous membranes of the bron- chia and intestinal canal, and sometimes, though extremely seldom, in the other mucous membranes. These produc- tions are susceptible of becoming organized like those of the serous membranes, yet this is of rare occurrence, be- cause they are ordinarily thrown off by the efforts of vo- miting, by stool, &c, or because the subject succumbs in the incipient stage of the organization; at other times, the in- flammation diminishes, and the internal tegument again * The arborescent inflammatory coloration is the only one which yields to washing and maceration; all the others do not undergo the least diminution of intensity. TEGU.MENTARY SYSTEM. 215 secretes a fluid, which raises the false membrane and de- taches it completely; or the secretion not taking place, the morbid production gradually diminishes, becomes semi- transparent, and finally entirely disappears. The acute inflammations of the mucous membranes sometimes termi- nate in ulceration: in this case their edges are somewhat jutting, extremely red, and covered, like their base, with a mucous puriform substance. These phlegmasia also sometimes terminate in gangrene, either by reason of their violence, or because of their essentially phagedenic cha- racter, as is the case in the anginose gangrenous epide- mics; the development of small vesicles upon the affected part often indicates this termination. The eschars of the mucous membranes vary from a grayish to a blackish- brown colour, and commonly present the appearance of a putrid deliquescence. In many subjects who die with croup there are symp- toms of mucous fever, an inflammation of the cryptse of the internal gastro-intestinal tegument, which produces genuine pustules, of a grayish or whitish colour, and filled with a mucoso-purulent fluid; in the centre of these pus- tules we observe a small depression or black point, which indicates the orifice of the crypta. This affection has been chiefly described by Rcederer and Valger. M. Bretonneau, of Tours, however, has paid much attention to the pustu- lous inflammation of the follicles of the mucous membrane of the intestines, and has given it the name of dothinente- ritis, — a disease which readily assumes a chronic cha- racter, and often terminates in ulceration of the affected cryptse. In small-pox the mucous membranes are some- times affected with pustulous inflammations: in these cases, the pustules, ordinarily superficial, though sometimes situated in the thickness of the chorion, are not constantly depressed, nor do they appear to have the areolar disposi- tion of those of the external tegument. The chronic phlegmasiae of the mucous membranes are 216 TKGUMENTAKY SYSTEM:. generally characterized by a bright red,-livid or copper-co- lour, and by a thickening and hardening of the affected parts, whose tissue is of a more homogeneous nature than in the normal state. — The growths, which are sometimes observed on the surface of the mucous membranes, result from a morbid development of their capillaries, occasioned by a protracted irritation or chronic inflammation. The ulcerations, which are produced by chronic inflammation, are characterized by hard, elevated, jaggy edges, while the base of the ulcer is rugose, and of a red, livid or copper-co- lour: this morbid state is generally accompanied by the se- cretion of puriform or purulent matter, even where there is no ulceration. Polypi of the mucous membranes and the erectile productions, which are sometimes accidentally de- veloped in their thickness, as well as the cartilaginous and osseous metamorphoses, may also be referred to protracted irritation or chronic inflammation. The mucous mem- branes are often the seat of sanguineous congestions, which may be either active or passive, accordingly as they are oc- casioned by the irritation of their tissue, or by an obstruc- tion in the circulation. In these cases the thickness, density, and consistence of the membrane are in no wise altered, nor is there any mor- bid secretion upon its surface. These congestions may bring on hemorrhage and even inflammation. The mu- cous membranes are sometimes, though rarely, the seat of pilous and corneous productions; when these are exposed for a certain time to the atmosphere they assume the cha- racters of the external teguments. The membranes which line fistulous openings, certain cysts, and most of the puru- lent abscesses, may be referred to the order of mucous membranes. TEGUMENT ARY SYSTEM. 217 SECTION 4. Of the Appendages of the Tegumentary System. The appendages of the tegumentary s) 7 stem are the solid parts which are produced by the bulbous or phaneric folli- cles, and project upon the free surface of the teguments. These parts are: — the hairs and the nails for the external tegument, and the teeth for the internal. — Before we enter upon the particular history of each of these products, we shall endeavour to give a general idea of the generative part — the bulb. The bulb is a small vesicle, which is situated in the thickness of the dermis, opens upon its free surface, and is continuous by the margins of its orifice with the tegumentary membrane, of which it is really a mere de- pression: in fact, the small organ of which we are speak- ing is composed, 1st, of a lamina which is analogous to the dermis, and which, being in relation with the sub- cutaneous cellular tissue, gives passage to blood-vessels and nerves which ramify principally upon its concave surface; 2d, of a pulpy substance which is formed, as it were, of the termination of the blood vessels and nerves of the chorion, and represents the retemucosumof Malpighi; 3d, and lastly, of the dead inorganic product, which is analogous in this respect, and sometimes also in its chemi- cal composition, to the epidermis. article 1. Of the Hairs. Definition. — The hairs are the filamentous inorganic parts, which project upon the free surface of the external tegument, and are of variable length, fineness and delicacy. 29 218 TEGUMENTAUY SYSTEM. Division and situation. — The hair is distinguished by different names according to the part where it is situated, as capillus, on the scalp; supercilium, on the eye-brows; cilium, on the eye-lids; circi'inus, on the temples; barba, on the chin, and mystax, on the upper lip. The generic name of hair, moreover, is applicable to all the pilous pro- ductions which occur upon the surface of the trunk, and the extremities. There are no hairs in the palm of the hand and the sole of the foot; and they are extremely thin and delicate in some parts of the face, the internal parts of the extremities, and on the back: they generally occur in considerable abundance on the sternal parts of the thorax, and the external parts of the extremities, particularly in the male. Form. — The generative part, or pilous bulb, represents a small ovoid vase, which is open on the free surface of the teguments. The hair, properly so called, is of a conical form, being more delicate at its free than at its bulbous ex- tremity. It is either straight, twisted, or curled. Structure. — The bulb of the hair is really nothing but a small oblique depression of the skin, and consists of the same number of lamina?. The pigment itself exists in the part which represents the rete mucosum. The greater part of the bulb is filled by a cone of pulpy substance; and upon this papilliform body is implanted the inorganic part, or the hair properly so called. At its adherent part, the pilous follicle has capillary vessels and nerves which stimulate its small roots. The hair itself embraces, by its hollow and diffluent base, the pulpous cone of the bulb; and the surrounding epider- mis, after having invested the orifice of the bulb, is reflect- ed upon the base, and is confounded with the hair.* — The * This double mode of union of the hairs with the skin, renders the ad- hesion of these two organs so intimate, that it can not be broken without a certain degree of difficulty and of pain. All such efforts as have a ten- TEGUMENT ARY SYSTEM. 219 hair is a white epidermic sheath, containing a colouring matter which is disposed in numerous filaments, between which there is a liquid substance for the purpose of con- necting them with each other, and with the sheath. This interior coloured part represents the rete mucosum of the skin, and upon it depends the colour of the hair. — Neither blood vessels nor nerves can be traced into the substance of the hair itself, the bulb being the only part which re- ceives them. Characters, physical and chemical properties. — The colour of the hair varies in different individuals from white to jet black, passing through a number of intermediate shades of pale yellow, reddish, auburn, &c: it is never of a blue, green, or yellow colour, &c. In the Albinoes the hairs are of a white appearance. Their colour is generally the same in the different parts of the surface of the body; yet there are many exceptions to this rule. The thickness or diameter of the hairs is very different in the different parts of the same individual; thus, the hairs of the pubes are the thickest; and in regular succession those of the ax- illaa, the head, the eye-brows, the eye-lids, the beard, &c. The medium of this diameter is about the six hundredth part of an inch. Fair hair is generally the most fine and delicate; black, the most rough. The hairs greatly resist such causes as have a tendency to rupture them transverse- ly, but they are easily divided in a longitudinal direction. They are dry and solid externally, fluid at their adherent extremity, and soft within: they evidently absorb humidi- ty, and enlarge.* The hairs resist for a great number of years the action of putrefaction. By long continued boiling in Papin's diges- ter, they are gradually dissolved, and are finally converted dency to detach the epidermis from the subjacent laminae, have the same effect with respect to the hair of the scalp. * It is to a knowledge of this fact that we are indebted to the hy- grometer of M. De Chaussier. 220 TEOUMENTAUY SYSTEM. into mucus, after having disengaged a quantity of hydro- sulphuric acid gas. According to the analyses of Vauque- lin, black hair contains a large proportion of an animal sub- stance, similar in all respects to mucus, a white inspissated oil, a small quantity of thick oil of a greenish black colour, traces of the oxides of manganese and iron, of silica, sul- phur, phosphate and carbonate of lime, and sulphate of iron. According to this chemist, the colour of the hair de- pends upon the presence of the greenish oil, and the sul- phate of iron. This oily matter is either of a greenish black colour, red, yellow, or nearly colourless, according as the hair is black, red, yellow, or white. Vital properties. — The bulbs of the hair, and particu- larly the pulpy portions, are the only parts which enjoy any evident sensibility; the hair itself being completely destitute of vitality. The motions which are sometimes observed in the hairs depend upon the contractions of the cutaneous tissue. Differences in the different races of men. — The varie- ties of colour which we have just pointed out belong al- most exclusively to the individuals of the Caucasian race; and amongst them we may observe that those who inhabit the northern countries, have generally a fairer and lighter pilous system, than those of the southern regions. In all the other races the hair is black. In the Caucasian and Malay, the hair is generally long, fine, thick, and often curled; it is fine and thin in the American, short and coarse in the Mongolian, crisped and woolly in the Ethiopian. Differences according to age and sex. — At about half the term of pregnancy, the skin of the foetus is covered with an external soft and delicate down, which falls off sometime after birth, and of which traces may be found in the liquor amnii. The hair of the head, the eye-lids, and eye-brows, appear in the latter months of gestation, and are the first amongst the permanent pilous parts which are developed. The other hairs do not appear until after the TEGUMENT ARY SYSTEM. 221 age of puberty. In infancy the hair is generally more fine and soft, and of a lighter colour than in adult age. In the decline of life, (and sometimes before) the hairs become white and fall off: in old age they are white and thin. In the female, we generally observe neither beard,* nor whisk- ers, and the hair upon the chest and the external parts of the extremities are very thin and delicate. Functions. — The pilous bulb secretes the substance which forms the hair. — The hair is an organ of protection of the skin, and is subservient to the tactile sensations by the facility with which its generative pulp receives the im- pressions from such bodies as touch the hair. Pathological JLnatomy. When the hairs are plucked out, they are always repro- duced, provided the bulb, has not been destroyed: the same thing takes place in the diseases of the bulb which occasion the falling off of the hair, The bulb is sometimes com- pletely altered by a protracted inflammation, its pilous se- cretion ceases, and the hairs lose their colouring matter. This phenomenon, as we have already said, is a natural con- sequence of the progress of age, in which case the change of colour of the hair takes place in regular progression; but often, and chiefly, in consequence of moral impressions, such as fear and grief, they become suddenly hoary be- fore the ordinary period. In these cases they sometimes, though seldom, recover their primary colour. We are ignorant in the present state of our knowledge, of the changes which supervene in the follicles of the hairs after their removal or discoloration. In the disease called plicaj the hairs of the scalp acquire an extraordinary * There are some individuals of the female sex, however, who have a sort of beard, especially on the upper lip, which comes on either about the period of puberty, or after the cessation of the menses. f This disease, generally termed plica polordca, is almost peculiar to the inhabitants of Poland, Lithuania, and Tartary. — S. D. G. 222 TEGTTMENTAKY SYSTEM. length, and become entangled in a very intricate manner: some have even asserted that they become vascular and sensible; but perhaps there is nothing real in this opinion, which at least has been exaggerated. Beclard has endea- voured to account for the facts upon which this opinion rests, (the hemorrhage and pain which accompany their cutting,) by supposing, that in consequence of the irritation which the bulb experiences in the disease to which we have alluded, the pulp which secretes and embraces the hair tumefies, becomes raised above the level of the tegu- ments, and is then entangled by the instrument with which the affected part is shaved. Hairs are sometimes accidentally developed in conse- quence of inflammations of the skin, and even in those parts where they do not ordinarily occur. Numerous cases have been related in which hairs are said to have been found in the organs which are lined by mucous membranes; but in most of them they appeared to have been intro- duced. They have also been sometimes found in certain cutaneous cysts, and in the ovarium, in cases of extra-uterine pregnancy : in these instances the hair is extremely delicate, and of a whitish appearance. The hairs, which some au- thors, such as Bonet, and Amatus Lusitanus, are said to have found upon the heart, were probably nothing but mere pseudo-membranous filaments. ARTICLE 2. Of the Nails. Definition. — The nails are the hard, transparent lamellae, which cover the dorsal parts of the last phalanges of the fingers and the toes. Form and disposition. — The nails are oblong, and curved in such a manner as to be moulded upon the parts which they cover. They are divided into a root, body, TEGUMENTARY SYSTEM, 223 and free extremity. The root is posteriorly and is placed within a duplicative of the skin; it is the most soft and delicate part of the nail. The body is continuous with the root, which it exceeds in thickness; it presentsposteriorly a white semi-lunar part with the convexity before, which is called the crescent; in the rest of its exent, the body of the nail is of a faint red colour, and its transparency is such as to permit the colour of the subjacent cutaneous tissue to be seen. The anterior or free extremity, which is more thick than the preceding portion, projects more or less beyond the dorsal part of the finger. When nothing prevents its growth, the free extremity becomes long and crooked and acquires an increase of thickness. The nails present two surfaces, one of which is convex, the other concave; both are adherent at the posterior part, and free at their anteri- or extremity; at the middle part, the concave surface is adherent, but the convex surface is free. The nails adhere to the subjacent cutaneous laminae, throughout the whole extent of their circumference, by means of the surrounding epidermis which serves to unite them, without, however, its being confounded with them; and, besides, their root, which is lodged within a kind of furrow of the skin, is there intimately connected with it. Under the root of the nail, the dermis is of a whitish appearance, from which re- sults the semi-lunar spot called the crescent; under the mid- dle part, on the contrary, the dermis is very vascular, and furnished with small papillae. Structure. — The nails have been regarded by some anatomists, particularly by Bichat and J. F. Meckel, as being formed of a substratum of epidermic laminae, whose extent diminishes successively from behind forwards, in such a manner, that the most exterior layer forms the length of the nail, and the most internal its shortest part. This, in fact, appears to be the only true explanation of the differences in the thickness of the nails in the different parts of their extent. According to others, however, such 224 TEGUMENTAItY SYSTEM. as Blancardi and M. de Blainville, the nails are pilous pro- ductions, which are agglutinated together, and are derived from bulbs similar to those which we have described in the preceding article. Indeed, the longitudinal striae which are observed upon the two surfaces of the nails, would appear to indicate an analogy between them and certain corneous productions, which very evidently result from the aggluti- nation of a great number of hairs.* Notwithstanding, however, the plausibility of these opinions, we are una- ble to decide whether the nails are merely a thick corne- ous epidermic layer, or whether they are secreted by pi- lous bulbs. Characters, physical and chemical properties.- — The nails are whitish, t semi-transparent, hard, flexible and elastic, and, like the epidermis, they are principally com- posed of concrete albumen. Vital properties. — The nails are destitute of vitality. % Differences according to age. — The nails are brought into existence about the fifth month of foetal life. Their thickness and consistency, at first inconsiderable, gradual- ly increase, so that in old age they become very hard and firm. At birth, the nails do not always reach the extre- mity of the finger, and seldom jut beyond it. Functions. — In man, the nails serve merely to defend the free extremities of the fingers: the habit of paring them, common to most people, renders them unfit for la- ceration. * According to some anatomists, these stria: are owing to the linear disposition of the papilla; of the dermis. f In the coloured races, the pigmentum nigrum is situated in the sub- jacent parts, and the blackish appearance of the nails is entirely owing to their transparency. + The fact that so much pain is felt when the nails grow into the flesh, and that the operation of tearing them out is so extremely painful, is no doubt owing to the lesion of the surrounding parts. — S. D. G. TEGUMENTARY SYSTEM. 225 Pathological Jinatomy. When a nail has been torn out, or has been detached in consequence of a disease of the subjacent dermis, it is re- placed by another, which bears more or less resemblance to the first, accordingly as the generative part is healthy or altered; in the latter case, it may even happen that there will be no reproduction at all. The nails are often sub- ject to excrescences, or a preternatural thickening. In scro- fulous subjects, or those who are affected with chronic diseases, such as phthisis, &c, they often become more brittle, thin and convex, than in the healthy state. When the nails grow into the surrounding tissues, it often gives rise to a very painful affection, which may be attended even with inflammation of the skin which is in contact with • the sharp edge of the nail. This affection is almost exclu- sively confined to the great toe, and is occasioned by the wearing of tight shoes. ARTICLE 3. Of the Teeth. Definition. — The teeth are the small, hard, calcareous'or- gans which are fixed in the alveoli of the superior and in- ferior maxillse, and are produced by the follicles which are dependant on the mucous membrane of the mouth. Division. — Each tooth consists of a body and a root, or that part which is fixed in the socket. The boundary be- tween these two is called the neck of the tooth. Texture. — The teeth present two well marked and dis- tinct parts, one of which is organic, the other inorganic. The organic part consists: 1st, of a membrane which co- vers the root of the tooth and is continuous with the mu- cous membrane of the gums; 2d, of a neuroso-vascular pul- py substance which represents the form of the tooth, and is 30 226 TEGUMENTARY SYSTEM. surrounded by it on all sides, except in one or two points where it communicates with the preceding membrane by- blood-vessels and nerves. The inorganic part is exactly moulded upon the pulp, and is composed of two substances; one of which consti- tutes almost the entire tooth, and is called the osseous or ivory substance; it is disposed in laminae and has neither cellular tissue, blood-vessels nor nerves, nor the areolar tex- ture of the bones. The other substance is termed the ena- mel, and forms a layer which covers the preceding; it is of a white, milky, brilliant, semi-transparent appearance, more hard than the ivory part of the tooth, upon which it is exactly moulded, and becomes thinner as it approaches the neck of the tooth. The enamel has no trace of organiza- % tion; it is disposed in undulating fibres, which are united with each other in a very exact manner, and are directed obliquely in respect to the axis of the tooth. We see, then, that on account of their organization, the teeth could not have been included in the osseous system. Be- sides this distinctive character, and that which is drawn from the peculiar situation of the body of the teeth, we shall readily distinguish, in the remainder of this section, all the other differences which exist between the dental apparatus and the passive organs of locomotion. The den- tal apparatus is naturally placed upon the same line with the hairs, since it consists, like them, of a follicular part, a • generative pulp, and an exterior dead part; their chemical composition being the only difference which exists be- tween these two productions. Comparative anatomy throws but little light upon this subject, except by show- ing that the beaks of birds are analogous to the teeth of mamiferous animals. Characters, physical and chemical properties. — The teeth are of a white, very slightly yellowish appearance, especially in their alveolar part: the crown is more or less brilliant, on account of the enamel which covers it. The TEGUMENTARY SYSTEM. 227 hardness of the teeth exceeds that of the hardest and most solid bone in the body, (the petrous portion of the tempo- ral bone,) a property which they owe to their containing a greater quantity of calcareous matter. — According to the analysis of M. Berzelius, the osseous substance of the teeth is composed of phosphate of lime, 51.04, fluate of lime 2.00, carbonate of lime, 11. 30, phosphate of magnesia, 1.16, soda, 1.20, and a trace of the hydro-chlorate of soda, and,accordingtoMr. Pepis,of a small proportion of gelatine. According to the first named chemist, the enamel consists of the same salts as the osseous part, but in different proportions : the phosphate of lime, amongst others, being much more abundant in the latter than in the enamel, which, according to Hatchett, Fourcroy and Vauquelin, is composed of the phosphate of lime, in combination with a very small quan- tity of gelatine. Development, and differences according to age. — The changes which the dental apparatus experiences during the course of life are very remarkable and curious. Under this point of view, therefore, we may divide the teeth into two classes, the temporary and the permanent: the first, which have also been called the milk teeth, are twenty in number, are shed between the age of seven and fourteen, and are supplied by the permanent teeth. The temporary teeth are: eight incisores, four canini, and eight molares, to which are added, between the fourth and sixth year, four other molares, which do not fall out, like the preceding, and may be considered as permanent teeth. At the age indicated above, the twenty milk teeth are shed and are succeeded by an equal number of corresponding perma- nent teeth. The number of these organs, which is then twenty-four, (counting the four molares which remained,) afterwards amounts to thirty-two by the development of eight other large molares; four of which do not appear un- til between the age of eighteen and thirty, and are hence called denies sapientias. 22fc> TEGUMENTARY SYSTEM. The dental follicles begin to be apparent about the tenth week of uterine life, but they do not appear all at the same time. They consist at first of small, round, shut sacs, lodged in the alveoli and composed of two layers, an ex- ternal and an internal; the former of which is thick and in- timately adherent to the gums; the other, very vascular and delicate, is a kind of net-work which contains at first a reddish fluid, that is gradually changed to a pale yellow. About the fourth month, the bottom of this small sac con- tains the generative pulp, which in a short time assumes the form of the future tooth. About half the term of utero- gestation, this pulpy nucleus is covered by small laminoe of ivory substance, which are soon after succeeded by others, secreted in like manner upon the surface of the pulp. So long as this pulp is covered with earthy matter only in a small proportion of its extent, it is easily to be conceived, by the facility with which it can be separated, that their bond of union is merely inorganic, and is completely destroyed at a subsequent period, though they can not be possibly separated, because the ivory substance embraces every part of the original nucleus. The part of the nucleus which corresponds to the triturating surface of the tooth, is the first that is encrusted with the ivory sub- stance, so that its laminae are more numerous here than in any other part: the roots are formed after all the other parts of the teeth, of which they are mere prolongations, are fully developed. The enamel of the teeth is secreted and deposited upon the surface of the crown by the inter- nal lamina of the sac, and is easily separated in the foetus from the ivory substance. About six or seven months af- ter birth, the milk teeth pierce the sac which contains them, and finally the mucous membrane of the gums, with which the margins of the orifice of the sac or follicle be- come in a short time confounded: it is at this period that the root is developed. The different kinds of teeth are by no means formed simultaneously, nor do they appear ex- TEGUMENTARY SYSTEM. 229 teriorly at the same time. According to J. F. Meckel, the following general rules may be established in respect to the development and appearance of the teeth: " 1st, the different stages are regulated by the same laws, so that the follicle of the tooth, whose germ appears first, is also that which is first developed, ossified and pierced; 2d, the homonymous teeth of the same jaw generally correspond; 3d, the infe- rior teeth are developed before the superior, and the ante- rior before the posterior; 4th, the gradual development of the human teeth corresponds to the permanent forms which are found in the scale of mammiferous animals." The follicles of the permanent teeth begin to appear successively after the eighth month of fcetal life, and are at first situated in the same alveoli as those of the tempo- rary teeth, upon which they are then placed, and are united with them by their external lamina. These follicles are soon after removed from the milk teeth, are placed at their posterior part, and are subsequently observed to be lodged within particular alveolar cavities, which result from the slight depressions at the posterior paries of the primary cells: these depressions are converted into the true alveoli, by the development of a partition between the follicles of which we are speaking, and the parts which are occupied by the milk teeth. — The milk teeth are shed in consequence of the destruction of the vessels and nerves which connect them to the jaw; a destruction which is produced by the permanent teeth, which, during the progress of their de- velopment, compress these bonds of union, and destroy in regular succession all the adhesions of the temporary teeth, The pulp of the teeth, whether permanent or temporary, is much larger in proportion as it is examined near the pe- riod of dentition; subsequently, its vitality gradually di- minishes, and is finally completely destroyed: the shed- ding of the teeth in advanced age, is a more or less imme- diate consequence of this complete atrophy of their living part, On the other hand, the continual friction of the 230 TEGUMENTARY SYSTEM. teeth destroys by degrees their enamel, and exposes the ivory substance. Under these circumstances it sometimes happens that the osseous part itself is worn away to the dental pulp, which, in this case, secretes a new osseous sub- stance, which is more soft than the first, and serves the purpose of filling up the cavit) r of the tooth. Function. — The incisores and canini serve to seize and to rend, the mokres to triturate the food; neither of them can, however, exclusively perform one of these functions. Pathological ./inatomy. The form of the teeth is often very variable, and far from being in relation with the normal type: the eminences which surmount the crown may be more numerous and projecting than ordinary; and the roots themselves may present the same kinds of anomaly, or their distribution may be unnatural,* so much so, that the fangs of two con- tiguous teeth may become united. The number of teeth is often less, and sometimes, though rarely, greater than that which we have indicated; in some instances, there is even a double row of these organs. In general, the supernu- merary teeth are more common to the superior than to the inferior jaw. In some instances there is a third dentition a very long time after the second: the teeth are also some- times transposed; for example, a molar tooth may occupy the place of a canine, &c. The development of the teeth often takes place in a preternatural order; and we not un- frequently observe the persistence of one or more of the milk teeth, after the corresponding permanent teeth have been already developed, and issued from their sockets. When a tooth has been fractured, it does not become con- * In the anatomical museum of the celebrated Albinus, is an instance of the body of a molar tooth growing into the antrum highmorianum, the direction of the roots being reversed. Mayo's Outl. of Physiology, p. 125.— S. D. G. TEGUMENTARY SYSTEM. 231 solidated, if it is the crown that has been affected; if the root, however, be injured, its proper membranous en- velope secretes an osseous substance which re-unites the fragments. Inflammation of the dental pulp is by no means of rare occurrence, and occasions the most severe pain. It some- times terminates in suppuration or gangrene, and very often in caries of the affected tooth : this last disease attacks particularly the teeth which have been deprived of their enamel, and more frequently the molar teeth than any other. The diseases of the gums and the jaws may also influence, in a very considerable degree, the health of the teeth. There are sometimes adventitious dental productions, especially in certain ovarian cysts. Bibliography of the Tegument ary System. The works already quoted. Hebriard. Memoire sur l'analogie qui existe entre les Systemes muqueux et dermo'ide; Memoires de la Societe medicale d'Emulation, vol. VIII, p. 153. Bonn. De continuationibus membranorum. 1763. On the skin in particular. Malpighi. De exter. tact, organ, in Epist. Londres, 1686, p. 21—33. Gaultier. Recherches sur l'organisation de la Peau de l'homme, et sur les causes de sa coloration. Paris, 1805), Recherches sur l'Organe cutane. Paris, 1811. Dutrochet. Observations sur la structure de la Peau, dans le Journal complem., vol. V. Meckel. De la nature de l'Epiderme et du Reseau qu'on appelle Malpighien; dans les Memoires de l'Academie de Berlin. 1753- Les OCuvres &\<2lbinus renferment plusieurs travaux sur 232 TEGT7MENTARY SYSTEM. Panatomie ties diverses couches cutanees, sur les causes dc leur coloration, etc. Ch. Th. Reus. De glandulis sebaceis dissert, etc. Tu- bingse, 1807. Hintze. De papillis cutis tactui inservientibus. Leyde, 1747. Meckel. Nouvelles observations sur Pepiderme, dans les Memoires de Berlin, ann. 1757. Ducrotay de Blainville. Principes d'anatomie comparee, torn. I. Paris, 1S22. Gendrin. Histoire anatomique des inflammations, t. I. Paris, 1826. Bateman. Abrege pratique des Maladies de la Peau, tra- duit de Panglais par S. Bertrand, in-8vo. Paris, 1S20. Jllibert. Description des maladies de la Peau, etc., gr. in- fol. Paris, 1S06. Precis theorique et pratique sur les maladies de la Peau, torn. I et II. in-8vo. Paris, 1S22. P. Bayer. Traite theorique et pratique des maladies de la Peau, fonde sur de nouvelles recherches d'anatomie et de physiologie, torn. I. in-8vo., avec atlas idem. Paris, 1S26. On the Mucous Membrane. Peyer. De Glandulis intestinalium. Amstel., 1681. Brunner. De glandulis duodeni. Francofurt., 1715. Helvttius. Mem. de l'Academie royale des Sciences. Paris, 1721. Liebernkuhn. De fabr. et act. villos. intestin. horn., in-4to. Lugd. Bat, 1744. H. Buerger. Examin microsc. villos. intestin. cum icon., in-8vo. Halae, 1819. Leuret et Lassaigne. Recherches physiologiques et chim- iques pour servir a Phistoire de la digestion, in-8vo. Paris, 1826. Billard. De la Membrane muqueuse gastro-intestinale TEGUMENT ART SYSTEM. 233 dans l'6tat sain et dans l'6tat inflammatoire, etc., in-8vo. Paris, 1825. Gendrin. Ouvr. cite, torn. I. On the Appendages of the Tegumentary System. 1. The Hair. P. Chirac. Letter a M. Regis sur la structure des Che- veux. Montpellier, 1688. Malpighi. De Pilis observationes, in op. posth. Daverney. (Euvres anatomiques. Paris, 1768. C. Jls. Rudolphi. Diss, de Pilorum structura. Grisps- wald, 1806. Gaaltier. Ouvr. cite. Heusinger. Remarques sur la forme des Poils, dans Jour- nal complementaire du Dictionn. des Sciences medicales, torn. XIV; et sur la regeneration des poils, idem, idem, p. 339. Plenck. De morbis capillorum, in doctr. de morb. cut. Meckel. Memoire sur les Poils et les Dents qui se devel- oppent accidentellement dans le corps; in Journ. com- plementaire du Dictionn. des Sciences medicales, torn. IV, p. 122—217. 2. The Nails. B. S. Mbinus. In Annot. acad. Lib. II, cap. XIV, de un- gue humano, et cap. XV, de naturS unguis. Ludwig. De ortu et structure unguium. Lips. 1748. Haase. De nutritione unguium. Lips., 1774. Plenck. De morbis unguium; in op. cit. 3. The Teeth. «/?. Serves. Essai sur l'anatomie et la physiologie des Dents, ou nouvelle theorie de la Dentition. Paris, 1817. Geoffroy-St.-Hilaire. Systeme dentaire des Mammiferes et des Oiseaux, embrassant sous de nouveaux rapports les principaux faits de l'organisation dentaire chez l'homme. Paris, 1824. 31 234 TEGUMENTARY SYSTEM. J. Fr. Meckel. Essai sur le developpement des Dents chez Phomme; dans Journal complementaire du Diet, des Sciences medicales, torn. I, p. 365. F. Cuvier. Des Dents des Mammiferes, ets. Paris, 1822 a 1825. Onze livraisons in-8vo., avec figures. J. Fox. Histoire naturelle des maladies des Dents de l'es- pece humaine, traduit de l'anglais par Lemaire. Paris, 1821. J. Lemaire. Traite sur les Dents. Paris, 1822. OF THE GLANDULAR SYSTEM. 235 CHAPTER IX. OF THE GLANDULAR SYSTEM, Definition. — The glandular system consists of a certain number of organs, furnished with numerous excretory ducts which unite in one common trunk, in order to terminate upon the surface of the teguments and to evacuate the fluids which are separated from the blood in the interior of these organs. The glands which properly belong to this system are, the three salivary, the lacrymal, the liver, the pancreas, the mammas, the testicles and the ovaria. * * The sebaceous and mucous follicles, as well those which are isolat- ed as those which occur in groups, as the muciperous glands of Peyer, (in the ilion) or rather those which open upon the tegumentary surface by common ducts (lacunse,) may be placed under the same head as the glands that have just been enumerated, and from which they differ merely in being less complicated, but being, like them, mere prolonga- tions of the teguments. Indeed, is not a slight degree of attention suf- ficient to convince us that there is no essential difference between the amygdala or the prostate, &c, and the lacrymal or salivary glands? On the other hand, the term gland is sometimes applied to a number of parts which have only some resemblance as regards the more gross relations of form or texture. And without speaking here of the tongue, which, on account of its rounded contour, might be placed in the glan- dular system, we shall notice: 1st, the lymphatic ganglia, which are called conglobate glands, in contra-distinction of the true organs of se- cretion, which are termed conglomerate glands,- 2d, certain rounded or- gans, which are enveloped by a membrane which varies in thickness, and sends prolongations into their interior: these organs, which Bichat has 236 OP THE GLANDULAR SYSTEM. Situation and arrangement. — The glands are found exclusively in the trunk, and are either in symmetrical pairs, and situated upon each side of the mesian line, as the lacrymal, the salivar) 7 , the mammary, the kidneys, the testicles and the ovaries, or they are single, and are placed upon the mesian line, or upon one side, as the pancreas and the liver. •■ Conformation. — The form of the glands is very varia- ble; but they are always more or less rounded, and often flattened in one or more directions. They differ also still further in respect to their volume; what a difference is there between the size of the liver, one of the largest or- gans of the body, and the lacrymal gland? Structure. — The anatomical composition of the glands results, 1st, from a purely cellular, or fibrous envelope, which is' in relation by one of its surfaces, either with cellular or adipose substance, or with a serous membrane, and is confounded by the other with the tissue of the glands; 2d, from vessels, nerves, and excretory ducts, whose most minute ramifications are united by cellular tissue and form the proper parenchyma of the organ. In all the glands, except the liver and the kidneys, the parenchymatous sub- stance is divisible into lobes and lobules, which result from the union of whitish, homogeneous particles. On the con- trary, the organs to which we have just alluded, are com- posed of two substances, which are easily distinguished by separated from the glandular system, are essentially vascular, are desti- tute of excretory ducts, and are, according 1 to modern anatomists, true sanguineous ganglia, which are analogous to the lymphatic ganglia, and in which the blood that circulates in their interior is destined to under- go a process of perfection. The thyroid and thymus glands, the spleen and the capsulx renales, compose the group of these organs, which have received the name of adenoid or glandiform bodies, and of which we can not give a general description, on account of the diversity of their form, their structure, and the obscurity in which their true character is still involved. OF THE GLANDULAR SYSTEM. 237 the difference of their colour. In the kidneys, these sub- stances are disposed in layers, an exterior and an interior, or a cortical and a medullary, but in the liver, they exist every where simultaneously. But in what relations do the most minute ramifications of the vessels and of the excretory ducts stand, so as to form the proper tissue of the glands? Shall we admit with Malpighi that the radicles of the excretory ducts are small vesicles or follicular pouches, in the parietes of which the blood-vessels terminate; or that the excretory ducts are, as was asserted by Ruisch, the immediate continuation of the vessels? Acknowledging that this point of minute anatomy is still extremely obscure, it is to the first of these hypo- theses that we would cede the preference, following in this respect the example of the greatest modern anatomists. Indeed, the study of comparative anatomy teaches us that the glands are the mere agglomerations of numerous folli- cles which belong to the canalicular and ramified pro- longations of the tegumentary membranes. (i The muci- perous glands, which are nothing but simple sacs, form the prototype of the glandular formation. Let us imagine that the branches of this elongated ramified sac unite with those of the vessels, and we shall have the most intricate gland, without there being any immediate communication between the blood-vessels and the excretory ducts." — J. F. Meckel. The excretory ducts, after being successively joined so as to form large branches, finally unite in one or more trunks which terminate upon the surface of the teguments. In their course, which is sometimes very considerable, the trunks often present enlargements, which are small, as those of the mammary glands, or large and cystiform, as those which constitute the gall-bladder and the vesicular semi- nales: the urinary bladder may be considered as an enlarge- ment common to the excretory ducts coming from each of the kidneys. The mucous membrane, which essentially 238 OF THE GLANDULAR SYSTEM. constitutes the glandular apparatus, gradually becomes thinner and more delicate in proportion as the ramifica- tions of the excretory ducts become more numerous. This membrane, however, is strengthened and protected by cel- lular substance which is more or less compact, sometimes even fibro-elastic, and in some parts by a vascular erectile net-work, or muscular fibres. The glands contain numerous blood-vessels and lymphatics; and all, except the liver, re- ceive exclusively arterial blood. This organ receives, be- sides its particular artery, a large venous trunk (vena porta?,) which is ramified in its substance, (See Vas. Sys. ) In general, the veins of the glands do not exceed their cor- responding arteries in capacity, as is the case in the other parts of the system; a circumstance which is owing to the loss which the blood, that is carried to them by the arteries, experiences in these organs. Characters, physical and chemical properties. — Their colour, density and consistence, vary in the different glands, and can not be described in a general manner. The chemical characters of the compound glands depend upon those of the elementary tissues which contribute to their formation. Vital properties. — The glands appear to be destitute of vital contractility, and in their healthy state, they are but little sensible; the testicle being the only one that manifests any considerable degree of sensibility when it is compress- ed. The presence of calculous concretions in the excretory ducts of some of these glands, and especially in those of the liver and the kidneys, generally occasions severe pain and distress. Differences according to age. — The glands in the hu- man embryo are developed in passing through the different stages of complication which are observed in the skin of animals; and this mode of development proves that these organs are nothing but more or less complicated appen- dages of the tegumentary system. Indeed, the parts which form the excretory canals are perceived to be, at first, OP THE GLANDULAR SYSTEM. 239 continuous with the teguments, which are afterwards suc- cessively ramified until the gland is completely formed. In the foetus, these kinds of glands are composed of lobes and lobules, which, in some of them, as in the kidneys, subsequently disappear. The volume of the glands, which concur to the preservation of the individual, is generally comparatively greater in the early periods of life than in after age. On the contrary, the mammae, the testicles and ovaries, which are destined to the preservation of the spe- cies, are usually small before the age of puberty, when they become larger and acquire more vitality: in old age they cease to act and fall into a kind of decay. The testicles and the ovaries, moreover, change their situation some time before birth. Functions. — The glands serve to separate from the blood, which circulates within them, particular fluids which differ in the different kinds of glands, and are conveyed to the surface of the teguments by the excretory ducts. The separation of these products constitutes what is called se- cretioriy which differs from the perspiration and follicular secretion only by the intricate structure of the secretory organ. The manner, however, in which the glandular secretion is effected, is still unknown, and all the knowledge we possess upon this subject is, that the blood, after its ar- rival in the capillary arteries, which are distributed in the proper substance of the organ, has some of its materials com- bined, either by virtue of a simple chemical re-action favour- ed by the dilatory course of this fluid, or under the influence of a vital action, exercised upon it by the tissue of the follicles of the gland. The changes in the vitality of a gland, and the state of its nervous system, have a great influence upon the nature and the quantity of its secretion; and from this combination results a peculiar fluid which is discharged into the excretory ducts, and conveyed by them to the sur- face of the teguments, or retained for a certain time in their cystiform cavities. The blood, which has not been employ- 240 OF THE GLANDULAR SYSTEM. ed in the formation of the humour to which we have just alluded, is taken up again by the radicles of the vascular centripetal system. Pathological Anatomy. There are few organs which present more congenial anomalies pf volume, form and situation, than the glands. They are often larger and again much smaller than usual, either primarily, or, as is most ordinarily the case, acci- dentally: they are sometimes affected with atrophy, which may either result from their compression, or from the ces- sation of their functions. The lobular structure which is sometimes observed to continue in some of the glands, es- pecially in the kidneys, depends upon their imperfect de- velopment. The kidneys are the organs which are the most subject to anomalies of number; thus, there have been instances where there was sometimes but one, and at others, three of these glands. The ovaries and the testicles are sometimes entirely wanting; and their situation also may be anomalous: thus, there have been instances where the ovaries passed out of the abdomen, and where one or both testicles remained in that cavity, after the time when they ought to have descended into the scrotum, and even dur- ing life. The solutions of continuity of the glands cicatrize with difficulty, and have a tendency to become fistulous, because the secretions, flowing continually, prevent the re-union and agglutination of the lips of the wound. The glands are extremely subject to inflammation; and this morbid state is capable of producing different pheno- mena in the different kinds of glands, and even of being propagated to the tegumentary membrane. It suspends, augments, or alters their secretion, and often induces the induration of their tissue by the exhalation of an albumin- ous or sanguineous fluid during the inflammatory process. This induration, which ordinarily accompanies the oblite- OP THE GLANDULAR SYSTEM. 241 ration of at least a part of the excretory ducts, often be- comes schirrous or carcinomatous, when the inflammation continues to exist: these alterations are frequently conse- quences of chronic inflammations of the mammae, the tes- ticles and the ovaries, The glandular tissue is never pro- duced accidentally; but the different transformations and accidental productions are observed in all of them, and par- ticularly in the mammae, the testicles and the ovaries. Bibliography. The treatises on general anatomy already quoted. M. Malpighi. De viscerum structural, cap. II, in op. omn. De gl. conglob. Ep., p. 6. Opera posth. H. Bcerhaave et Ruisch. De structura glandul., etc. ; in Ruisch op. omn. Th. JBordeu. Recherches anatomiques sur les Glandes. Paris, 1751. G. «#. Haase. De Glandularum definitione. Lips., 1804. 32 542 MUSCULAR SYSTEM. CHAPTER X. MUSCULAR SYSTEM. SECTION 1. General Observations. Definition. — This system consists of an assemblage of organs — the muscles — which compose the greater part of the body, are characterized by a more or less evidently fibrous structure, and by extensive contractions, by virtue of which they are the agents of locomotion. Division. — Bichat, struck with differences of form, the organization and functions which exist between the exte- rior voluntary, and the interior membraniform involuntary muscles, established two muscular systems, which he de- signated according to their most prominent and distinctive characters, by the nanies of the muscular system of ani- mal life, and the muscular system of organic life. More lately, anatomists, aware that the relations which exist be- tween these two systems in respect to their organization, their properties, &c, are too important to be separated in an absolute manner, have united them under the common denomination of the muscular system, and have divided the muscles themselves into two classes. Structure. — The muscles consist of an assemblage of primitive microscopic fibres united in fasciculi, which are easily distinguishable by the naked eye (secondary fibres); but these fasciculi form still larger ones, which, by uniting MUSCULAR SYSTEM. 243 with others, form the muscles. In order to perceive the fasciculi, it is necessary to subject a muscle to the action of ebullition; we shall then be able easily to detach them under the form of flattened or prismatic filaments, which extend either throughout the whole length of the muscle, or they terminate before they arrive at its extremity, by uniting with the tendons or the aponeuroses. The fila- ments, or secondary fibres which compose the fasciculi, are always parallel, but this is seldom the case with the fasci- culi which compose the body of a muscle; they being almost always oblique in respect to each other. Ex- amined with the microscope, the fibres, like the fasciculi, present still smaller fibres, which appear to be the ultimate parts of the muscles, and are hence called the elementary or primitive, or simply the muscular fibres. The phy- siologists who have paid particular attention to the struc- ture of the muscular fibre, are Prochaska, the Wenzells, Autenricth, Sprengel, Mr. Bauer, and Sir E. Home, Messrs. Dumas and Prevost, and M. Dutrochett. In the present day these fibres are generally regarded as small, somewhat flattened filaments, having every where the same diameter, and being composed of a series of globules which are exactly analogous to the white globules of the blood, and are united together by a perfectly transparent mucous, or gelatinous substance. Every thing else that anatomists have advanced upon the ultimate structure of the muscular fibre, is of a hypothetical nature. The muscular fibre, and consequently the secondary fibres, and the fasciculi, pre- sent, when they contract, transverse wrinkles, which are nothing but temporary folds that disappear as soon as the cause of contraction is removed. These phenomena are more conspicuous in the belly of the muscle than at its extremities, which are both drawn towards its middle. Besides the proper substance of the muscles, which ap- pears to be formed of globules, and the transparent medium in which they are disposed in linear orders, these organs 244 MUSCULAR SYSTEM. contain cellular tissue, blood-vessels, lymphatics, and nerves. The cellular tissue forms a general covering (or the muscles, dips into their substance, and forms a sheath for each fasciculus, and probably for each elementary fibre: here, however, the existence of the cellular substance can only be admitted by analogy. The tenuity and consistence of this substance gradually diminish, in proportion as its divisions become more minute. (V. His. of Int. C. Tissue.) Adipose substance also occurs in the interior of the mus- cles, between their fasciculi, and even between their se- condary fibres. The number and caliber of the vessels of the muscles are considerable, and are proportionate to the volume of the different muscles which compose the two classes of the muscular system. The arteries having reached the cel- lular envelope of these organs, divide into numerous branches, which are distributed in different directions, be- tween the fasciculi, and terminate by successive ramifica- tions in the cellular tissue, and the secondary fibres, be- yond which they can not be traced: we are still ignorant of the relations which exist between the elementary fibres, and the blood-vessels of the muscles. The muscles have but few lymphatic vessels; and the veins, which are larger and more numerous than the arteries, are divided into su- perficial and deep seated; the latter of which generally ac- company the arteries. It is not, however, to the presence of these numerous vessels, but to another cause, which we shall hereafter point out, that we are to attribute the colour of the muscles; for this is not in relation with the quantity of the blood which penetrates these organs; it remains, not- withstanding the changes which the colour of the blood experiences in cases of suffocation. The nerves of the muscles are exceedingly numerous, and are derived, either from the encephalo-rachidian masses, or from the gan- MUSCULAR SYSTEM, 245 glionic system, accordingly as these muscles belong to the first or to the second class of the muscular system.* In some instances the same muscle receives several nerves from different origins: in this case it appears, ac- cording to the researches of Mr. C. Bell, that the plurality of the nerves is not intended for the accumulation of a greater quantity of the nervous energy in the muscle, but to enable it to perform several kinds of motion. Let this, however, be as it may, it is certain that the nerves general- ly enter the muscles by following the course of the blood- vessels, proceeding either parallel with, or perpendicularly to the fasciculi and muscular fibres, in which they soon be- come undistinguishable. The imagination of the anato- mist has supplied what inspection can not demonstrate in respect to the termination of the nervous filaments, and he has supposed that the substance of the nerves is either lodged in the cellular tissue, and communicates to it its conducting property (Isenflamm), or that a nervous atmo- sphere, emanating from these filaments, extends from the seat of innervation to their termination. According to the microscopic observations of MM. Prevost and Dumas, it appears that the nerves of the mus- cles extend farther than they can be traced by the naked eye; that after a nerve has ramified a certain number of times, it becomes expanded, and that its secondary fasci- culi shoot out, and give off filaments which traverse the muscular fibres at a right angle, and either form a kind of loop and return to the same nerve, or anastomose with the neighbouring branches. These transverse filaments are very numerous and near each other; and, in general, the small nerves which furnish them proceed parallel with the muscular fibres; and in some instances two of them pass together, and in such a manner as to give off an equal num- * We have already seen to what part of the cerebro-spinal masses the nerves correspond which preside over the voluntary motions, 241) MUSCULAR SYSTEM. ber of filaments which intersect the muscular fibres per- pendicularly. From these observations it would really ap- pear, that the nerves have no termination, since their ulti- mate divisions anastomose with the neighbouring branches, or return to join their original trunk. Characters, physical and chemical properties. — The colour of the muscles varies, according to the class to which the} 7 belong, from a grayish white to a deep red; and ap- pears to be much more intense in proportion as the muscle is thick and large; there being scarcely any, where the fibres are isolated. The colour of the muscles does not depend upon their vascularity, but upon the presence of a colouring mat- ter which is analogous to that of the blood: by washing a portion of muscle, the colouring matter will remain sus- pended in the water; it may also be readily separated by boiling, and when a muscle is exposed to putrefaction, it immediately disappears. The muscular fibre is semi-transparent, soft, slightly elastic, endowed with the power of resisting considerably during life, especially during its state of contraction, and enjoying a remarkable degree of contractility. By slow desiccation it is rendered more prominent, transparent, and hard. After death the muscular fibre yields readily to such efforts as have a tendency to break it. The action of ebullition, the dilute acids, alkohol, and the different saline solutions, render the muscles more consist- ent and more evidently fibrous. The chemical analysis of muscular flesh has furnished the carbonate and phosphates of lime, of soda and ammonia, a small quantity of albumen, gelatine, osmazome, and a considerable proportion of fibrin. The marked predominence of the fibrin in the chemical composition of the muscles, establishes a very striking relation between them and the clot of the blood, and tends to prove, that the sanguineous globules and those of the mus- cular fibre, which are already identical by their form, are also bv their chemical nature. MUSCULAR SYSTEM. 247 Vital properties and f mictions. — The muscles possess a middle degree of sensibility in the healthy state, but in certain morbid affections, especially in inflammations, their sensibility becomes considerably exalted. They enjoy the highest degree of vital contractility or irritability (Haller,) a property upon which depends the character which they enjoy in the animal economy. What are the phenomena of this contractility of the muscles, or rather what is contraction? When a muscle acts it becomes shorter and thicker, as well as more dense and hard. The first of these phenomena being the most important, and the others being mere consequences, it is it which has induced physiologists to give to the muscular action the name of contraction. It has been often asked whether, during contraction, the muscles gain exactly in thickness what they lose in length; and whether their vo- lume augments, diminishes, or remains the same. The best conducted and most satisfactory experiments upon this subject, and amongst others, those of MM. Meckel, Prevost and Dumas are favourable to the last hypothesis. When the muscles contract, they become corrugated, but do not undergo any change of colour, as has been supposed by some anotomists. — Having thus briefly pointed out the changes which a muscle experiences when in a state of ac- tion, we shall next inquire what phenomena takes place in the different parts of the muscles? The muscular fibres are drawn in a zigzag direction throughout the whole ex- tent of their length, and this in such a manner that the apaces of the sinuositus. which they form are always the points where the nervous filaments intersect the fibres at a right angle, (Prevost and Dumas) so that the contraction is owing to the sinuous direction of the muscular fibres. Phy- siologists have endeavoured to determine the extent of the shortening which the muscular fibre experiences: during the state of contraction, according to Bernouilli, it is as one third to that of the fibre: while Prevost and Dumas esti- 248 MUSCULAR SYSTEM. mate it at one fourth, according to the extent of the angles formed by the zigzag direction of the fibre, — a fact which is confirmed by direct observation. The possible degree of rapidity of muscular contraction varies in the different muscles; but it is always considerable. In certain muscles, a part of the fibres remain at rest while the others contract: this phenomenon is chiefly observed, as has been proved by the experiments of Mr. C. Bell, in those muscles which receive their nerves from different sources. When the muscles contract, they acquire elasticity, and the force which they sometimes display during this state, is so great as to break their connexions with the tendons and the bones: this force is in direct ratio with the number of their fibres. Physiologists have at all periods endeavoured to explain muscular contraction, and have assigned to this phenome- non, either mechanical or chemical causes, according to the prevailing theories of the time. Haller, after having refuted such explanations as these, thought he had ascer- tained the true cause of contraction, and asserted that it took place by virtue of a peculiar property, which he term- ed irritability, and which since the time of Bichat, has received the name of contractility: but this was merely expressing a fact in an abstract manner, and not explaining it. It is to MM. Prevost and Dumas that we are indebted for the most ingenious hypothesis that has hither- to been proposed upon this subject. These experimenters assert, as we have already had occasion to state, that the nervous filaments, which are distributed to the muscles, in- tersect their fibres at a right angle, and are of opinion, that these filaments are traversed by a current of galvanic fluid which attracts them towards each other, and that this at- traction is the cause of the zigzag direction of the fibres to which the nerves are attached. According to this theory the muscular fibres are passive in the phenomena of con- traction, while the nerves themselves are the true agents. MUSCULAR SYSTEM. 249 Several physiological and pathological facts also go to sup- port this explanation. The analogy which is supposed to exist between the cause of the vital contraction of the mus- cles and that of the phenomena of galvanism, would appear evident by the contractions which a dead muscle, or sim- ply its nerves manifest when they are exposed to the ac- tion of the galvanic pile. These, however, are mere hy- potheses, and in the present state of our knowledge we are still ignorant of the proximate cause of muscular contrac- tion; though it is otherwise with regard to the conditions of the muscles themselves; for we know, 1st, that it is ne- cessary for a muscle, in order to produce vital contrac- tions, to be (a) in a healthy state; (b) that its communica- tions with the heart by means of the vessels, and with the nervous centre by means of its nerves, should not be in- terrupted ; and (c) that when the nervous centre is in a state of disease it suspends its influence upon the muscles. 2d. In order that contraction may take place, it is necessary there should be an exciting cause; this does not always ex- ist, nor is it the same in all the muscles. Thus, the will acts only upon the muscles of the first class, while all those of the second contract under the influence of the moral af- fections, the irritation of the encephalic centre, the stimulus of the internal and the external teguments, the sthenic state of the membranes, or the cellular envelope of the muscles, and under the direct mechanical, chemical, or galvanic ex- citement of the muscles, or of their nerves alone. When the cause of contraction ceases to act, the organ recovers its primary dimensions, a phenomenon which some anatomists consider as a vital action, and not as the simple effect of the elasticity of the fibres; this opinion, which is entertained by J. F. Meckel, does not appear to be more plausible than that of Berthez, who attributes to the muscles a power of fixed situation. Mode of development and differences according to age. — At the commencement of uterine life, the muscles 33 250 MUSCULAR SYSTEM. are confounded in the mucous mass which represents the cellular tissue: their fibrous structure is not distinct until about the third month; but the pulsations of the heart, which begin at a much earlier period, indicate a preco- cious organization of the tissue of this organ. The mus- cles are at first soft, gelatinous, and ver}- pale. According to Bichat, their galvanic irritability is much less during foetal life than in the subsequent periods; while the experi- ments of M. Meckel go to prove the contrary. During infancy, the muscles are still pale and soft, and have a much smaller proportion of fibrin than subsequent- ly; though their movements are more prompt and easy than in the following periods of life.* In the adult, the muscles are^>t the maximum of their colour, their fibrinous composition and vital energy; their form is more distinct; their movements less rapid, but more sure and steady than in the infant. In old age, the muscles become pale and acquire a certain degree of hardness and rigidity, and their contractions also become slow and feeble. In the female the muscles are, cce.te.ris paribus, rounder, more soft, and less powerful than in the male; and their contractions are also more feeble and rapid. There do not appear to be any other differences be- tween the different varieties of the human races, in relation to the muscular system, than those which generally result from the health of the individual and his mode of living: civilized people, therefore, enjoy a very marked superior- ity over savages, in respect to the development and energy of their muscles. After death, the muscles may be observed to contract, during a certain time, under the influence of certain stimu- • Supposing that this circumstance is concomitant with the imper- fection of the organization of the muscular fibre, and with a great sus- ceptibility of the nervous organs, we are induced to regard these last as the true agenis of contraction. MUSCULAR SYSTEM. 251 li; but, as regards this, it is to be remarked, 1st, that the time, during which the muscles remain sensible to artifi- cial excitement, varies in the different muscles; 2d, that all of them cease to be irritable to the action of one stimu- lus, while they are still so to another, and that, in this respect, the organs of which we are treating can not all be placed in the same class; thus, the heart is still irritable under the influence of mechanical agents, after it has ceas- ed to be so by the galvanic action, even after the contrac- tility has been exhausted in every other part of the system: on the contrary, the exterior muscles are still irritable by the action of the galvanic pile after they have ceased to be so by mechanical agents.* The muscular contractility remains until about twenty- four hours after death. The cause of this, and the prior state of the subject greatly influence the irritability of the muscles in the dead subject. When the subject has died suddenly in consequence of violence, or apoplexy, and all other things being equal, the muscles retain their irrita- bility for a much longer time than under ordinary circum- stances. When the passage from life to death has been less sudden, the muscles contract a much longer time un- der the influence of external excitants, in proportion as the disease has been less protracted, and has had less influ- ence upon the assimilative process. In persons who die * Several experimenters have endeavoured to point out the order of succession in which the muscles cease to be capable of contracting 1 . Haller, Frosiep, and Nysten, have left us different results upon this sub- ject. Those, however, which the latter physiologist has obtained from his experiments upon decapitated subjects and upon animals, appear to deserve the most confidence. According- to him, the irritability leaves successively the aortic ventricle, the large intestine, the small intestine and the stomach, the urinary bladder, the pulmonic ventricle, the oeso- phagus, the iris, the exterior muscles of the trunk, those of the inferior extremities, and finally those of the superior extremities, and the right and the left auricles. 252 MUSCULAR SYSTEM. from the action of the deleterious gases, such as the car- bonic, the sulphurous, the hydro-sulphurous, &c, or from the stupifying poisons, the muscular irritability promptly disappears. When the muscles are no longer susceptible of contract- ing under the influence of stimuli, they become rigid and cold. Nysten considers the first of these effects as the last phenomenon of irritability, an opinion which is contradict- ed by that which regards the nerves as the true organs of muscular contractions: indeed, the cadaverous rigidity of the human subject, and in the scale of animals, is much harder and more precocious as the nerves lose more rapid- ly ther galvanic excitability. This fact would induce us to believe that the phenomenon to which' we have just al- luded has no analogy with the true muscular contractions; perhaps we ought rather to refer it to those contractions which are observed by dividing certain tissues in the dead body, and which the immortal Haller has attributed to a vis mortua, and Bichat to the contractility of tissue, both of which are, however, by no means capable of affording the true explanation. The muscular contractions have for their object, either to impart movements to the solids or fluids, or to maintain them in their proper situation. The mode of action of the muscles and the great variety of its results depend upon the number, the disposition and length of the fibres and fasciculi, &c; but chiefly upon the state of firmness or degree of mobility of the points to which they are attached. The muscles are called congeners or antagonists, accord- ingly as they act in the same or in opposite directions. The antagonism is chiefly observed between the muscles of the first, but sometimes also between those of both classes, as for instance, between the sphincters and the muscles of the fecal and urinary excretions. The contraction of one muscle is always accompanied by that of its congeners, and by the relaxation of its antagonists. MUSCULAU SYSTEM. 253 Pathological Jlnatomy. The muscles sometimes present mal-conformations which are almost always congenital, and consist chiefly in an ex- cess or defect of length, divisions, anomalies of attachment &c. They are frequently observed to be in a state of atro- phy and hypertrophy: the first is the result of their want of action, and is chiefly observed in cases of paralysis, or where the muscle has been exposed to protracted compres- sion; the second is the effect of too severe exercise, and is observed only in the interior muscles, and especially in the heart. The displacement (luxation) of the muscles has only been observed in cases where the aponeurotic envelopes of the muscles were divided. The muscles are sometimes susceptible of experiencing transverse ruptures in conse- quence of violent contractions, either of themselves, or of their antagonists, or under the influence of sudden and ex- cessive extension: these solutions of continuity, however, chiefly result from the violent contractions of the muscles at the point of union of the muscular fibres with the ten- dons, or the aponeuroses of insertion. The heart is some- times ruptured in consequence of its violent contractions, in certain cases of dilatation of its cavities (aneurism), es- pecially if its parietes are at the same time thin and weak. When a muscle has been divided transversely, either in consequence of rupture, or by a cutting instrument, the borders of the solution of continuity separate, and imme- diate re-union can not be effected; but the extremities of the organ secrete a fluid which fills up the space between them, becomes organized, and ordinarily acquires the tex- ture and appearance of fibrous tissue. This intermediate tendinous part, at once isolates and re-unites the two parts of the muscle; but we are ignorant whether they both con- tinue to contract. Be this as it may, it is evident that the movements which are produced by the muscles thus re- 254 MUSCULAR SYSTEM. united, are for a long time feeble, and seldom recover com- pletely, their former extent and firmness. It is supposed that in proportion as the separation and the tendinous part of the muscle are more considerable, the longer and the more imperfect will be the re-establishment of its motions. Moreover, as the tendinous part never ac- quires all the firmness and resistance of the muscular fibre, and as it remains extensible, it neutralizes in great mea- sure the effects of the contraction of the muscle. Wounds of the muscles which are attended with denudation and loss of substance, are covered by a cicatrix, which results from a process similar to that which we have described in the first chapter. Inflammation of the proper substance of the muscles is still doubted; but their cellular tissue is often inflamed, as is satisfactorily proved by the collections of purulent mat- ter which are observed between their fasciculi. In some instances, the muscles are remarkably flaccid and pale; and we not unfrequently meet with a gelatinous substance be- tween their fasciculi and fibres, in consequence of rheuma- tism. Are the fatty transformations of the muscles only apparent, as is supposed by Beclard, and do they consist merely in a preternatural development of the inter-fasci- cular adipose tissue of these organs, in those cases, where their pale and shrivelled fibres are easily confounded with the adipose substance? The muscular tissue is seldom affected with schirrous and carcinomatous degenerations; and as to its accidental development, all the cases that have been noticed may evi- dently be referred to morbid productions, whose appear- ance created some illusion. May we consider with some physiologists, the development of the muscular texture of the uterus during pregnancy as a kind of temporary acci- dental production? MUSCULAR SYSTEM. 255 SECTION 2. Of the Exterior Muscles. Synonyma.- Voluntary muscles, muscles of animal life (Bichat), muscles, properly so called. Definition. — The exterior muscles are those which, be- ing spread beneath the external tegumentary, and around the osseous system, are subject to the will. Situation. — The exterior muscles are in relation with the osseous or cartilaginous parts of the skeleton, with the skin, the cartilages of the larynx, the organs of the senses, and with the orifices of the digestive, the genital and urin- ary passages. Most of these muscles are in pairs, and are situated on each side of the body, some, however, are sin- gle, and extend from the mesian line to either side. Number. — Anatomists are not agreed as to the number of the exterior muscles; some include in one the fasciculi, which others regard as so many distinct muscles; according to the differences of their calculations, they vary in num- ber from three to four hundred. Volume, form, and arrangement. — There is a very great difference between the volume of the different mus- cles: to be convinced of this, it is only necessary to com- pare the triceps cruralis, and some of the other large mus- cles of the trunk, with the small muscles of the bones of the ear. The muscles, like the bones, may be divided according to their form, into long, flat, and short. The first belong more particularly to the extremities, and the second to the trunk. The third occur chiefly on the head, the neck, the hands, the feet, and generally around the short bones. The form of the muscles, also, which compose each of these groups, varies very considerably. Most of the exterior muscles present tendinous or apo- neurotic extremities, one of which is termed the head, and 256 MuscuLAn system. the other the tail; while the intermediate or fleshy part is called the belly. The belly of the muscle is either formed of a single fasciculus, or it consists of several very distinct bundles, which are separated by cellular tissue, as in the deltoid, and the glutaeus maximus; at other times, the body of the muscle is interrupted in its length by tendinous fibres, which divide it into several bellies, as in the digastricus of the neck, and the rectus of the abdomen. In some in- stances one of the extremities of the muscle is divided into two, and even into three portions, as is the case with the biceps, and the triceps brachialis and cruralis, &c. To these muscles may be compared the serrated muscles of the trunk: besides all these, there are other muscles which are simple throughout their whole extent, and have a com- mon tendinous extremity, as for instance, the latissimus dorsi, and the teres major, which are inserted by a single tendon into the os humeri. The muscles are always sym- metrical on each side of the mesian line; the diaphragm forming the only exception to this rule. They are almost always attached through the medium of their fibres to the periosteum, to the perichondrium, and to the organs of the senses; the fleshy fibres of the cutaneous muscles, however, furnish an exception to this rule, they being immediately inserted into the dermis, whose tissue, as we have already seen, greatly resembles the fibrous. The muscular fibres are often inserted into the membranous prolongations which are sent between the muscles by the aponeurotic envelopes. Structure. — The bundles and fasciculi which compose the muscles are much more evident in the exterior than in the interior muscles; the fasciculi of some of the former are often so distinct and voluminous that one might consi- der them as so many muscles. The muscular fibres pass in various directions, being sometimes parallel with each other, or in radiating lines, &c. In the first instance, the fibres unite and present a straight direction, or they pass MUSCULAR SYSTEM. 257 obliquely, either between two aponeuroses which are spread upon the muscle in part or in whole, or upon a tendon that is first concealed in the interior of the muscle, which often presents in its free part the appearance of the plume of a feather, either upon one or both sides: hence the names of semi-penniform and penniform muscles. It would be foreign to our subject to point out the different relations which exist between the muscular fibres, or between them and their tendinous parts; they are details which belong to descriptive anatomy: we shall only observe that the adhe- sion of the muscular fibres with the tendons is very firm and intimate. The quantity of the cellular tissue of the muscles is in direct ratio with their volume, the size of the fasciculi, and the interstices which separate them. In the general observations of the muscular system we have al- ready seen the relations which exist between the vascular system and the muscles, and it only remains to observe, that their nerves are extremely numerous, and are derived chiefly from the spinal marrow, and the medulla oblongata; though some of them, as the muscles of the neck and pelvis, are furnished with filaments from the ganglionic nerves. Physical properties. — The colour of the voluntary mus- cles, as every body knows, is of a deep red. The density and power of resistance of these organs are, as is supposed by anatomists, in direct ratio with the number of" their fibres, and exceed those of the muscles of organic life, &c. Vital properties and functions. — The sensibility of the voluntary muscles is scarcely observable in the healthy state*: they contract with much force and rapidity under the influence of the encephalic action; and when they are rem&ved from this influence, they may still be excited to contract by the stimulus of galvanism. The attitude and movements of the skeleton, the motions of the organs of the senses, of the skin, the voice, of speech, and degluti- tion, the retention and expulsion of the excrementitial mat- ters, are all the result of muscular contractions. These 34 258 MUSCULAR SYSTEM. movements are either simple or compound: they are sim- ple when they take place in the direction of the contrac- tion; compound when the muscles which produce them have two or more different directions. The general terms of congeners and antagonists, are applied to the flexors and extensors, the adductors and ab- ductors, and to the elevator and depressor muscles, &c. We generally observe different degrees of power between the antagonist muscles, which can only be studied in those which perform the motions of flexion and extension. Since the time of Borelli, these differences have been considered as being advantageous to the extensors; but it appears that this opinion is correct only with respect to some parts of the body, as for instance, the superior extremities. In the dis- position of the muscles there exist some very important cir- cumstances, which render it necessary that there should be a considerable force on their part'in order to produce mo- tion; these are, 1st, their levers of the third kind; 2d, the very acute angle which they generally form by their in- sertion into the apophyses, or into the extremities of the bones; 3d, the resistance of the antagonist muscles. We shall not include under these circumstances the obliquity of the fibres with respect to the tendons into which they are inserted, since this obliquity increases the number of fibres, and amply compensates for the loss which each of them sustains: as to the frictions of the tendons and of the articular surfaces, they are facilitated by the presence of the sheaths, and of the synovial membranes, in such a man- ner, that they can scarcely be considered as obstacles to be overcome by the muscular power. In relation to the first two circumstances which we have just presented as unfa- vourable to the muscular power, it may be observed; 1st, that if the levers of the third kind are more difficult to move, they are the most favourable to the extent and ra- pidity of motion; 2d, that the facility of motion is confined to the form of the body, and that this form would be very MUSCULAR SYSTEM. 259 unfavourable to locomotion, if the muscles were attached to the bone at a right angle: we perceive, moreover, how the extent of motion would be impaired by such an ar- rangement. section 3. Of the Interior Muscles. Synonyma: Hollow muscles, involuntary muscles, muscles of vegetative functions, muscles of organic life. Definition. — The system of the interior muscles com- prehends the fleshy parts which enter into the structure of the organs of the involuntary functions: these parts are, the heart and the planes of the muscular fibres which enter into the composition of the teguments of the gastro-pulmonary and the genito- urinary passages. Situation. — All the interior muscles are situated deep- ly, and belong, with the exception of the heart, to the in- ternal tegumentary system. Volume, form and disposition. — The volume and form of these fleshy parts generally depend upon those of the hollow organs, to the structure of which they contribute. They form muscular laminae which vary in thickness, and serve to strengthen the internal membranes of the organs to which we have just alluded. These laminae, which are very thin and few in the digestive canal and the urinary bladder, are more numerous and thick in the heart, are al- ways interlaced with each other, and are generally circu- lar: in the oesophagus and the large intestines they are longitudinal and intersect the first, which are exterior to them, at a nearly right angle. Structure. — The fibres which compose the muscles of organic life are sometimes interlaced; sometimes in juxta- position and united in flattened fasciculi: in this case they sometimes form almost complete rings, as may be observ- 260 MUSCULAR SYSTEM. cd in the greatest part of the- intestines. In general, these fibres are short; those even which compose the longitudi- nal fasciculi of the oesophagus and the large intestines, far from having the length of these organs, terminate after a short course, to give way to others: they are more or less distinct according to the organ that is examined; those of the uterus being only slightly manifest during pregnan- cy. The tendinous parts of the interior muscles occur only in the heart, at the extremities of its columnar carneae, at the entrance of its cavities, and in the auriculo-ventricular valves; the fibres of the other interior muscles terminate in the submucous cellular tissue, which we have already de- scribed in the first chapter of this manual. The interior muscles present but little cellular tissue: their vessels appear to be more numerous than those of the exterior muscles; but, as has been already observed, the vascular branches which penetrate into their tissue should not all be regarded as belonging to these, for the most of them are distributed to the internal teguments. The nerves of these are less numerous than those of the preceding muscles: most of them are derived from the ganglia, and anastamose in some of the organs with the cerebro-spinal nerves, — which is observed in the oesophagus, the stomach, the rectum and the urinary bladder. Physical characters. — The muscular fibres which cover the internal tegument are of a pale grayish appearance; those of the heart, however, are of a deeper red than those of the voluntary muscles. Bichat thought that the muscu- lar fibres of organic life were more resisting than those of animal life; but the contrary appears to be the more proba- ble, though if there be any difference in this respect, it has not yet been proved. Vital properties and functions. — The sensibility of the involuntary muscles is very obscure, and can with difficul- ty be appreciated and distinguished from that of the tissues with which they are connected. Harvey has cited the case MUSCULAR SYSTEM. 261 of a man, whose heart, being exposed in consequence of a caries of the sternum, could be irritated without pain to the patient. Bichat supposed that the first sensation of hunger results in part from the long continued state of contraction of the muscular fibres of the stomach. The contractions of the muscles of organic life are physiologically determined by the contact of certain agents, such as the blood for the heart, the aliments, the chyme, the chyle, and the excre- mentitial remains for the muscular planes of the digestive canal, and the urine for those^of the bladder: it ought to be observed, that these different substances stimulate the or- gans to which we have just alluded, only through the me- dium of the mucous or vascular tunic which covers them. These contractions may also be produced by mechanical stimulants; galvanism, on the contrary, operates with diffi- culty, while we recollect with what facility it unfolds the irritability of the voluntary muscles. A great number of morbid states of the economy determine or accelerate sym- pathetically the muscular contractions of the heart and of the submucous fleshy planes; but more frequently those of the first. Violent moral affections give rise to the same result; but, on the other hand, the muscles of which we are speaking are more or less independent of the ence- phalic action: we have no power of suspending the con- tractions of the heart, though Bayle, it is said, had this faculty, and Cheyne refers to a similar case; nor can we by the direct act of our will, contract our alimentary canal; and we can very readily explain, the influence of this last upon the urinary and fecal excretions, by that which it ex- ercises upon the exterior muscles which assist in its func- tions. Notwithstanding this independence, we find that it is" not absolute in many diseases where the cerebrospi- nal centre is injured, without the muscles of organic life be- ing affected, and that many affections of the encephalon and spinal marrow paralyse more or less promptly the organs of which we are treating: this is particularly the case with 262 MUSCULAR SYSTEM. the urinary bladder and the rectum, on account of the nerves which they receive from the spinal marrow; so that when this is injured, it gives rise to paraplegia, occasioning most frequently a simultaneous paralysis of these parts. The contractions of the interior muscles have for their object the contraction and shortening of the hollow organs of which they form a part: the variety which is observed in the direction of their fibres, is necessary, in order that this contraction may accommodate itself to the form of these or- gans, and take place in every direction. From this disposi- tion, the solids or fluids which are contained in the organs just alluded to, receive a motory impression, either for the purpose of propelling these substances from one part to another, or to expel them from the economy. The interior muscles have no antagonists that may-be compared to those of the exterior muscles; though we may, in some measure, consider as such: 1st, the foreign substances which distend the parietes of the hollow organs, of which the interior muscles form a part; 2d, the different portions of the hol- low organs with respect to each other: for instance, the auricles of the heart with respect to its ventricles, the first being at their height of contraction when the second are at their minimum of relaxation, and vice versa; the same also obtains with respect to the neck of the uterus and of the urinary bladder in relation to the bodies of these organs; 3d, the longitudinal fibres of the digestive canal with re- spect to circular fibres, the contraction of the first giving rise to the elongation of the second; 4th, sometimes the voluntary muscles, as for example, the sphincters of the anus and the bladder with respect to the muscular fibres of these organs: indeed, the latter are relaxed while the for- mer contract. In some instances, also, the exterior mus- cles act as congeners of the interior; thus, during vomiting, the act of defecation, of urinary excretion, and of parturi- tion, the abdominal muscles contract simultaneously with the stomach, the rectum, the bladder and the uterus. MUSCULAR SYSTEM. 263 Bibliography of the Muscular System. The general treatises already cited. Proschaska. De carne musculari tractatus anat. physiol. in op. minor.; pars I. Viennae, 1820. Privost et Dumas. Memoire sur les phenomenes qui ac- compagnent la contraction de la fibre musculaire; dans Journal dephysiologie experementale, t. Ill, p. 301 — 339. Dutrochet. Observations sur la structure intime des sys- temes nerveux et musculaires, et sur le mecanisme de la contraction chez les animaux; dans ses Recherches anat. et physiol. sur la structure intime des vegetaux et des animaux, et sur leur mobilite. Paris, 1824. Haller. Mem. sur la nature sensible et irritable des parties Hu corps humain. Lausanne, 1756 — 1759. De partibus corp. humani irritab.; in Comm. Gotting. Tom. II et in Nov. Comm. Gotting. Tom. IV. TVeber. De initiis ac progr. doctrinse irritabilitatis. Hallse, 1783. Borelli. De motu animalium. Leyde, 1500. Barthez. NouVelle mecanique des mouvemens de l'homme. Carcassonne, 1798. Roulin. Recherches sur les mouvemens et les attitudes de l'homme; dans Journal de physiol. experim. vol. I et II. Rites. Diet, des sciences medicales; art. Muscle, Muscu- laire et Myologie. G. Sedillot. Mem. sur la rupture muscul.; dans Mem. et prix du la Soc. de med. de Paris, 1817. Hausbrandt. Dissert, luxationis sic dictse muscularis refu- tationem sistens. Berolini, 1814. Fr. Schnell. De natura reunionis musculor. vulneratorum. Tubingse, 1804. APPENDIX, CONTAINING AN ACCOUNT OF THE ACCIDENTAL TISSUES. To complete the history of the anatomy of the tissues, it remains only to speak of those which are developed ac- cidentally. The accidental tissues are divided into those which have more or less resemblance to the natural tissues, and into those which can not be referred to any of the tis- sues of the healthy organs. The first constitute either the true accidental productions or simple transformations; and, as we have already had occasion to speak of the sys- tems to which they belong, we shall at present treat only of those which recede from the type of the normal organic formations. From the fact, that each of these tissues varies according to the part where, and the time in which it is ex- amined, and also from the fact that they often bear very delicate shades of resemblance to, and are often combined with, other tissues, authors have given very different clas- sifications, which it would be superfluous to enumerate on the present occasion. Confining our attention to the mor- bid tissues that have been most generally admitted, and are the best characterized, we shall successively describe the tuberculous productions, schirrus, cancer or the en- cephaloid substance of M. Laennec, and the melanotic sUb- appendix. 265 stance.* But before entering into the particular history of each of these, we shall point out, in a cursory manner, their general characters, and the principal notions that have been advanced with respect to their cause and mode of develop- ment. The morbid tissues may be developed in every part of the system, but they are more frequent in those parts which possess a considerable degree of vascularity. They occur most frequently in a single point, though sometimes they exist in several simultaneously. The relations of situation of these tissues with the organs, may be referred to two kinds; in one they occupy the interstices of the substance of the organ, which increases in size, and its substance, crowded and compressed by the presence of the morbid production, decays and disappears. In the second kind, they are formed on the exterior of the organ which they displace or destroy by compression, and finally, as in the preceding case, occupy its place. By some authors these morbid productions are consider- ed as degenerations of the normal tissues; while others profess, on the contrary, that they constitute new produc- tions, which are developed amongst the natural tissues. M. Meckel, amongst others, admits, that by an aberration of the nutritive process, analogous to inflammation, the organs become the seat of an effusion of albuminous fluid, which becomes imperfectly organised and assumes the dif- ferent forms of the preternatural tissues. M. Broussais also attributes the production of these accidental formations to inflammation of the capillaries, especially to that of the lymphatics; Bayle and Laennec, on the contrary, regard this phenomenon as the result of a morbid individual dia- thesis; but this opinion is supported by but few persons, the * The other accidental tissues admitted by Laennec, viz. cirrhosis, sclerosis, and the squamous tissue, do not appear to have been hitherto sufficiently studied, to be described with precision. 35 266 APPENDIX. greater number of anatomists and pathologists embracing the theories of MM. Broussais and Meckel. The accidental tissues, which have no analogy with those of the healthy system, do not, in general, present any ap- pearance of texture, though most of them contain blood- vessels and traces of cellular tissue. In proportion as they become appreciable, their consistence undergoes inverse changes of those which are experienced, in this respect, by the normal tissues; that is, instead of augmenting, their consistence progressively diminishes, so much sb, that these tissues, though sufficiently hard in their first crude stage, become soft, and finally, even fluid; they have a ten- dency to escape from the system, and exist only tempora- rily: instead of contributing to some function, they at first, mechanically impede the action of the neighbouring organs or of those into which they are infiltrated, often produce inflammation, and, subsequently, in their stage of decom- position, cause general and serious disorders, particularly emaciation and hectic fever, the precursors of a more or less speedy death. At this stage, also, the productions of which we are speaking, have a great tendency to become numerous, and are developed, sometimes, either simulta- neously, or successively in different parts, so that the sys- tem appears to be the seat of a general infection. article 1. Of Tubercles, Tubercles are homogeneous case i form productions, which are either infiltrated into the areolae of our organs, or are united in rounded masses. They occur chiefly in the lungs, in the tissue of the lymphatic ganglia (scrofulous tubercles,) in the cellular tissue, on the surface of the serous and the mucous membranes; in fact, there is no organ in the body that may not be affected with them. The tuberculous sub- \ APPENDIX. 267 stance is, at first, in a fluid state, and of a whitish appear- ance; but it gradually acquires more and more consistence, becomes yellow and assumes the aspect of cheese, consti- tuting what is called its stage of crudity: at this period, the tubercle is often enveloped by a soft membrane which is subject to various changes. Such is the stage of devel- opment of the tuberculous masses. They have neither vessels, nor cellular tissue, in a word, no trace of organi- zation. After some time, they undergo a softening, which begins at their centre and extends gradually towards their circumference: the tubercles are now reduced efther to an opake, yellowish, homogeneous, semi-fluid substance, or they are observed in the form of flocculi, which resemble the cheesy substance of milk. In this stage, the tubercu- lous substance leaves the point in which it was collected, opens a passage for its escape from the system, and the cavity which it occupied often disappear? in consequence of the approximation and adhesion of its parietes: in other cases, however, the tuberculous matter remains, and the pa- rietes, which are ordinarily formed by the new membrane which serves as a cyst to the tubercle, continue to secrete puriform matter, or this membrane, which is at first some- whatanalogous by its organization to the mucous teguments, becomes cartilaginous or even osseous; a case of which has been lately reported by M. Laennec, to the Royal Acade- my of Medicine. Bayle regarded the tubercles as a production sui generis, different from the grayish transparent miliary granulations, of which he has left an excellent description. Laennec, admitting the peculiar nature of tubercles, and attributing them, in the same manner as Bayle, to a peculiar individu- al diathesis, disagrees with this author in considering the miliary granulations as the first stage of development of the tuberculous masses. M. Broussais does not separate these productions, and asserts that they consist in an alter- ation of the the lymphatic ganglia, produced in conse- 26S APPENDIX. quence of inflammation.* M. Andral, the younger, has been led, after an attentive examination of pulmonary tu- bercles and granulations, both in the human subject and in the horse, and after a minute dissection of the lobules of the lungs, to conclude: 1st, that the granulations of Bayle are not incipient tubercles, but portions of the lobules of the lungs, insulated and inflamed:! 2d, that the pulmonary tu- bercles are not composedof a tissue, since they do notpossess the anatomical characters; 3d, that they are the product of a morbid secretion, preceded by an active sanguineous con- gestion, which does not necessarily constitute inflamma- tion; 4th, that it is probable, but has not been proved, that the lymphatic ganglia of the lungs are often the seat of tubercles, (the lymphatic vessels of the lungs and of other organs sometimes contain a substance which appears to be identical with the tuberculous matter:) 5th, that tubercles occur in several of the tissues which compose the lungs.. article 2. Of Schirrus. Schirrus, which is often confounded under the name of encephaloid cancer, is a very hard tissue, of a whitish or bluish appearance, and is usually presented under the form of irregular masses. It is most frequently observed in the neck of the uterus, the pyloric orifice of the stomach, and in the glands; but there are few organs which may not be its seat. In its state of crudity, the schirrous tissue is of the consistence of fibro-cartilage, and grates under the scalpel. By examining its texture, we may observe traces of the cellular and the fibrous tissues, but seldom any ves- * Morton and Portal had already considered pulmonary tubercles as engorged lymphatic ganglia. | When the lymphatic ganglia are inflamed, they often assume the physical characters of these granulations. APPENDIX. 269 sels; interiorly, it is often cellular and presents regular radii like those of the turnip. This tissue often becomes softened, and is converted into a gelatinous or syrup-like substance, which is of a white, transparent appearance, or of a reddish, yellowish, or greenish gray colour. The schirrous tissue presents many varieties, and amongst others, those which Mr. Abernethy has distinguished by the names of the tuberculous, the mammary, and the pan- creatic sarcoma. The first is distinguished from schirrus, properly so called, by its lobular form. article 3. Of Encephaloid or cerebriform Cancer. The tissue to which M. Laennec has applied the name of encephaloid substance, is one of those which pathologists designate under the name of cancer, and which has been improperly called fungous inflammation (Burns,) fungous hematodes (Hey and Wardrop,) and medullary sarcoma (Abernethy.) This tissue is often found in the uterus, the ovaries, the testicles, the mammas, the brain; and, in fact, in every organ. It is presented under the form of lobular masses with convolutions like those of the brain: these masses are often covered, either in part, or in whole, by a membranous production, which is connected to them by a very loose, vascular substance, and often acquires the consistence of cartilage. In some cases, the cerebriform substance is infiltrated into the tissue of the organs, espe- cially in the uterus. In its state of crudity, the encephaloid tissue is of a white, rose, or purple colour, either partially, or in a uniform manner: it is less consistent than schirrus, and more firm than the substance of the brain. It is traversed by blood- vessels whose parietes are thin and brittle, and are derived from those which are found in the soft cellular tissue which 270 APPENDIX. covers the encephaloid masses. Notwithstanding the anal- ogy which exists between the encephaloid and the cerebro- spinal substances, both with respect to their form and their apparent texture, we ought not to admit the identity of their tissues. The cerebriform cancer soon becomes soft, and is con- verted into a pultacious substance, which is of a reddish white, and sometimes grayish colour, and resembles, in some respects, the softened substance of the brain. It often happens, at this period, that the vessels of the preternatural tissue break, and produce an effusion of a considerable quantity of blood: under these circumstances, the fluid is either discharged from the s)'stem at the moment of the rupture, or it is effused and operates in the same manner as the sanguineous apoplexies of the cerebral tissue, which are not followed by immediate death. The contact of the air greatly accelerates the softening of the cerebriform substance, and its putrid decomposition. article 4. Of Melanosis. This term has been applied by M. Laennec to a black, opake, preternatural production, which had already been described by several pathologists before him, and which has been considered by some authors as a variety of can- cer (Meckel), or of tubercles (Broussais). The melanotic substance occurs either in masses, which vary in number, volume, and form, or it is infiltrated into a great number of organs, and particularly into the lungs, in the cellular, the glandular, and muscular systems, on the surface of the serous and the mucous membranes, in the lymphatic ganglia, &c. When it occurs in masses, they are connected to the surrounding tissues by cellular sub- stance, which is traversed by blood-vessels that do not APPENDIX. 271 penetrate into the melanotic substance: this has no appearance of texture, and receives considerable firmness and tenacity from the membrane which envelops it. By its softening, which takes place in a very short time, the melanosis is converted into a blackish deliquescent substance, which, if it be not immediately discharged from the system, may be absorbed so as to colour the neighbouring solids and fluids. This softening does not influence the general health in so terrible a manner as that of the preceding produc- tions. The chemical analysis of the melanotic substance has shown that it is composed of a great quantity of the fibrin and colouring matter of the blood, a small quantity of albu- men, a considerable proportion of phosphate of lime, of the oxide of iron, of the subcarbonate of soda, and of the chlorate of sodium. Bibliography of Pathological Anatomy. Besides the works cited above: Morgagni. De sedibus et causis morborum. Bonet. Sepulchretum, sive anat. pract. Genevae, 1700. Prost. La Medecine eclairee par l'ouverture des corps. Paris, an XII. J. Cruveilhier. Essai surl'anatomiepathologique en gene- ral et sur les transformations et productions organiques. Paris, 1816. P. Payer. Sommaire d'une Histoire de l'Anatomie pa- thologique. Paris, 1810. Bayle. Sur les indurations blanches des organs; dans le Journal de Med., torn. IX, an VIII. Remarques sur les tubercules; Journal de Corvisart, torn. VI. Recherches sur la phtbisie pulmonaire. Paris, 1S10. Laennec. Journ. de Corvisart, tome IX. — Sur les me- lanoses; dans Bull, de la Soc. de Medecine; 1806. — art. Anatomie pathol. et Encephaloide, du Diet, des Sciences 272 APPENDIX. medicales. — Traite de l'auscultation mediate, 2 fol. 6dit. Paris, 1826. JBroussais. Histoire des phlegmasies chroniques, 4vo. edit. Paris, 1S26. Maunoir. Memoire sur le Fongus nematode. Paris, 1820. Breschet. Considerations sur une degen6rescence organ- ique appelee degenerescence noire. Paris, 1821. Supplement aux Considerations sur la Melanose; dans la Revue medicale, torn. VII, p. 79. +findral fils. Clinique m6dicale. Paris, 1824 — 1826. THE END. I \ . \ \ . / ' r • ? • «« ,-. » r-\-\ •<-| COLUMBIA UNIVERSITY LIBRARIES This book is due on the date indicated below, or at the expiration of a definite period after the date of borrowing, as provided by the library rules or by special arrangement with the Librarian in charge. DATE BORROWED DATE DUE DATE BORROWED DATE DUE C28(846)M25 QH2* Bay] 0» Ui — < g = >■ ■O «/}^^^^ !h- g : ;lo > =h«. z = J = !