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Title: General Anatomy, Applied to Physiology and Medicine, Vol. 2 (of 3) Author: Xavier Bichat Translator: George Hayward Release Date: January 7, 2018 [EBook #56147] Language: English Character set encoding: UTF-8 *** START OF THIS PROJECT GUTENBERG EBOOK GENERAL ANATOMY, VOL 2 *** Produced by Sonya Schermann, Les Galloway and the Online Distributed Proofreading Team at http://www.pgdp.net (This file was produced from images generously made available by The Internet Archive) Transcriber's Notes Obvious typographical errors have been silently corrected. Variations in spelling and punctuation remains unchanged. The various tables used curved braces to indicate groups. For clarity and to adjust to different screen/font sizes, these have been replaced by straight lines. An analytical table of contents for all three volumes was included with volume III. This has been copied into this volume and the appropriate section has been linked to the relevant pages. The outline Table of Contents was added by the transcriber. GENERAL ANATOMY, APPLIED TO PHYSIOLOGY AND MEDICINE; BY XAVIER BICHAT, PHYSICIAN OF THE GREAT HOSPITAL OF HUMANITY AT PARIS, AND PROFESSOR OF ANATOMY AND PHYSIOLOGY. Translated from the French. BY GEORGE HAYWARD, M.D. FELLOW OF THE AMERICAN ACADEMY OF ARTS AND SCIENCES, AND OF THE MASSACHUSETTS MEDICAL SOCIETY. IN THREE VOLUMES. VOLUME II. BOSTON: PUBLISHED BY RICHARDSON AND LORD. J. H. A. FROST, PRINTER. 1822. Table of Contents CAPILLARY SYSTEMS. EXHALANT SYSTEM. ABSORBENT SYSTEM. SYSTEMS PECULIAR TO CERTAIN APPARATUS. OSSEOUS SYSTEM. MEDULLARY SYSTEM. CARTILAGINOUS SYSTEM. FIBROUS SYSTEM. FIBRO-CARTILAGINOUS SYSTEM. MUSCULAR SYSTEM OF ANIMAL LIFE. ANALYTICAL TABLE OF CONTENTS. VOLUME FIRST. VOLUME SECOND. VOLUME THIRD. DISTRICT OF MASSACHUSETTS, to wit: District Clerk's Office. Be it remembered, that on the seventeenth day of April, A. D. 1822, in the forty-sixth year of the Independence of the United States of America, Richardson & Lord, of the said District, have deposited in this office the title of a book, the right whereof they claim as proprietors, in the words following, to wit: "General Anatomy, applied to Physiology and Medicine; by Xavier Bichat, Physician of the Great Hospital of Humanity at Paris, and Professor of Anatomy and Physiology. Translated from the French, by George Hayward, M. D. Fellow of the American Academy of Arts and Sciences, and of the Massachusetts Medical Society. In three Volumes. Volume II." 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 an Act entitled, "An Act supplementary to an Act, 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 extending the Benefits thereof to the Arts of Designing, Engraving and Etching Historical and other Prints." JOHN W. DAVIS, Clerk of the District of Massachusetts. CAPILLARY SYSTEMS. The two great vascular systems, with red and black blood arise and terminate, as we have said, in the capillaries, which form in the lungs, as in all the other parts the limits that separate them, and in which they are changed from one to the other. There are then evidently two capillary systems distinct from each other, and which are even opposite. One, generally spread throughout the body, is the seat of the change of red blood into black. The other, confined wholly to the lungs, exhibits an opposite phenomenon; it is in its divisions that the black blood becomes red. As the capillaries, which serve for the origin and termination of the black abdominal blood, are intermixed on both sides with those of the general capillary system, since in the abdomen they are continued with the arteries and in the liver give origin to the veins, I shall omit them in these remarks, and attend only to the general and pulmonary capillary systems. These two capillary systems, the first especially, deserve the more particular consideration, 1st, because the circulation is governed in it by laws wholly different from those of the other parts; 2d, because most of the important functions of life take place there, as secretions, nutrition, exhalations, &c.; 3d, because their small tubes are affected on many occasions by diseases, as they are the seat of inflammations, metastases, &c.; 4th, because animal heat is especially produced in these tubes, &c. The lowest species of animals have in reality only a capillary circulation. Their fluids do not move in great masses, in canals which carry them to all parts of the body, and afterwards bring them back again. There is only an insensible oscillation of these fluids, in tubes of the greatest delicacy and number. This kind of circulation is one of the points of contact, or rather of transition from animals to vegetables, which, destitute of the circulation with a sensible motion, have evidently like the zoophytes, that of an insensible motion and of the capillary vessels. I shall first examine the general capillary system, and afterwards the pulmonary. ARTICLE FIRST. OF THE GENERAL CAPILLARY SYSTEM. This system exists in all the organs; all are in fact composed of an infinity of capillaries, which cross, unite, separate and unite again, by communicating in a thousand ways with each other. The vessels of any considerable size, those among the arteries, in which the blood circulates by the influence of the heart, and those among the veins, which correspond to the first, have really no connexion with the structure of the organs; they wind along their interstices; and are lodged in the cellular texture that separates their lobes; but the capillaries alone essentially make part of these organs, they are so combined with them; that they truly enter into the composition of their texture. It is in this view, that we may with truth consider the animal body as an assemblage of vessels. From this first view, it is evident that the extent of the general capillary system is immense, that it embraces all the smallest divisions of our bodies, so that we can hardly conceive of any organic particles united without capillaries. It follows hence, that this system is not only an intermediate one between the arteries and the veins. It is from it, that all the exhalants, all the excretories, &c. go. It furnishes all the vessels that carry nutritive matter to our organs; we ought to describe it then as existing in parts where arteries do not penetrate, as well as in those where they do. I. General Division of the Capillaries. Since this system is not destined merely to unite the arteries to the veins, and change the black blood to red, it is evident that other fluids besides the blood, must circulate in them; this is in fact what observation proves. There are many parts in the animal economy, in which white fluids alone circulate. We know the hypothetical opinions of Boerhaave upon the white arteries, the decreasing vessels, &c. We shall find these opinions in all books; I shall only say here what accurate observation shows us. That there is in the general capillary system, parts in which the blood especially moves, others pervaded only by white, or greyish fluids, &c. is a thing of inspection, and has no need of proofs. But what is the proportion of these fluids in the different organs? it is this that must be examined; now there are parts where the blood predominates almost exclusively in the capillary system, others where it exists in part, and in which there is a portion of different fluids, others in fine in which these fluids alone are found. Of the Organs in which the Capillaries contain only Blood. It appears that in the muscular system, in the spleen, in certain parts of the mucous surfaces, as in the pituitary membrane, &c. the blood so predominates in the capillary tubes, that almost every other fluid is unknown in them; thus fine injections demonstrate few other vessels; the arteries and the veins are seen there in great abundance. The blood, or its colouring matter, is in them, as I shall say, in two different states; in one, it stagnates and serves then to colour the organ; in the other, it circulates and contributes to its nutrition, its excitement, &c. 3 4 5 6 Of the Organs in which the Capillaries contain Blood and Fluids differing from it. These organs are the most numerous in the animal economy. The bones, the cellular texture, the serous membranes, a part of the fibrous system, the skin, the vascular parietes, the glands, &c. &c. exhibit this arrangement in a very remarkable manner. To give an idea of the capillary system in this kind of organs, let us take one in which it is easy to examine it, the serous membranes, for example. When we lay them bare in a living animal, their transparency permits us to see in an evident manner that they contain but very little blood in their capillary system; there are many branches under them, but they appear to be only contiguous; raise, for example, in a small living guinea-pig the peritoneal coat of the stomach; the red arteries, which at first view appeared to be in this coat, remain untouched. These membranes, certainly owe their white or greyish colour to the small quantity of blood they receive from their small vessels, to which the next trunks give rise. After having thus exposed a serous membrane, in order to see the quantity of blood that is found in it in a natural state, irritate it with any stimulant; at the end of some time, it will be covered by an infinity of reddish streaks, which will be so numerous, that they will change its whiteness into the red colour of the mucous surfaces. Force fine injections into a dead body, they will so fill the capillary system of the serous surfaces, of those of the peritoneum, for example, that those surfaces will be wholly black, and appear formed only by a net-work of vessels, whilst very few are apparent in the living body, because it is not the blood that fills them. When we cannot open animals to convince us of this, surgical operations, in which the intestines are laid bare, the peritoneum being untouched, wounds of the abdomen, the cesarian operation, &c. will prove incontestably that in the natural state, the blood fills ten and even twenty times less of the vessels, upon the serous surfaces, than injections show us in their texture. Examine these surfaces in chronic and acute inflammations, of which they are the seat, in the first especially, they exhibit a vascular net-work, so full of blood, that their redness is often deeper than that of the muscles. All the organs of which I have spoken above, exhibit the same phenomenon. Observe what takes place in the skin; fine injections show there infinitely more vessels than are filled with blood in a natural state; the face of a child well injected, is wholly black. Who does not know that oftentimes from the effect of passion, the blood fills with great rapidity, in the skin of the cheeks, numerous vessels, which in a calm state of mind are not apparent? Examine the conjunctiva, taken as an example in inflammations; frequently in a short time it changes its white to a bright red, because the blood fills vessels, in which it did not before pass; you can easily distinguish these vessels with the naked eye; you can see that the blood accumulated in this membrane, is not effused, but that it is contained in real vessels. I take for example the organs that have one of their surfaces free from adhesion, because the state of the capillary system is more easily distinguished in them; but the others present the same phenomenon; we shall see that the cellular texture, certain fibrous organs, &c. &c. examined comparatively, on the one hand in animals that we dissect alive, on the other in an inflammatory state or after fine injections, present a much less number of vessels in the first, than the second case. It can then be established as an incontestable fact, that in many of the organs of the animal economy, the general capillary system is, in the ordinary state, entered in part by blood, in part by other different fluids, that appear to be white. The proportions vary singularly; thus the capillary system of the serous membranes contains hardly any blood as I have said; that of the skin more; the mucous surfaces still more, &c. But whatever may be the relation, the difference is not less real in the capillary system. Perhaps also there are always in this system empty vessels, destined to receive fluids under certain circumstances; thus the urethra, the excretory ducts in certain cases, the orifices of the lacteals in the intervals of digestion, contain nothing. It is difficult to conceive of the rapidity of the passage of the blood in the capillaries of the face, and in those of other parts of the skin, if these vessels contain a fluid, which is to be displaced by the blood. However, nothing but what is founded upon experiment can serve to decide this question. Of the Organs in which the Capillaries do not contain Blood. These organs are less numerous than the preceding. They are the tendons, the cartilages, the hair, certain ligaments, &c. Dissected in a living animal, not a single drop of blood escapes from these organs, and yet there is no doubt that capillaries exist in them; oftentimes very fine injections demonstrate them there. Inflammation, also, frequently fills these capillaries with blood. Into the hair, this fluid enters in the plica polonica, &c. The non-vascular appearance of these organs in the living body, is illusory; it is because their fluids are divided into very small streams, the circulation of them is more slow, and their colour different from the blood, that we cannot perceive them. II. Difference of Organs in respect to the number of their Capillaries. Though the capillaries exist every where, yet they are more or less numerous in the different organs; in making fine 7 8 9 injections, it is easy to be convinced of this. What anatomist has not been struck by the prodigious number of vessels in this way developed, upon the skin, the serous surfaces, the cellular texture, &c. compared with those in the fibrous organs, in the muscles even, &c.? I have sought for the cause of this difference, and it has not appeared difficult to find it, since where injections develop few capillaries, there is only nutrition going on, as the bones, the muscles, the cartilages, the fibrous bodies, &c. are a constant proof; on the contrary, in all those in which many fluids enter, there are, besides nutrition, other functions, such as exhalation and secretion. Hence why a serous surface, almost as white as a cartilage in the living body, becomes ten times darker than it by the same fine injection; why the skin, compared to the fibrous organs, exhibits the same phenomenon; why in proportion to the arteries that enter a muscle and a gland, the latter admits much more injection than the other. These observations, which are uniform and invariable, prove that the capillary system is as much more developed in a part, as it has more functions to sustain. Observe in fine, that it is a kind of depot in which the fluids remain for a certain time, before serving for nutrition, exhalation and secretion. Where these three functions are united, it is necessary that there should be more fluids there, than where only one of them exists; hence more capillary vessels. The capillary system is not then in the organs in proportion to their size; a portion of the pleura contains more vessels than a tendon that is ten times larger. It is the nutritive substance that fills the place that these vessels do not occupy. We might, from what has just been said, divide the systems into two classes, from the development of their capillaries; place on one side the serous, the mucous, the glandular, the dermoid, the synovial, the cellular, &c.; on the other the osseous, the cartilaginous, the fibrous, the arterial, the venous, the fibro-cartilaginous, &c. The first class surpasses the second, considerably, in the number of its small vessels. Observe, also, that inflammation, different eruptions, all the affections, in which there is, as it is called, an afflux of humours to a part, are infinitely more frequent in the first than the second class, because all these affections are essentially seated in the capillary system, which is more developed in them. Asphyxia, apoplexy, and all the affections that make the black blood stagnate in the general capillary system, prove the same thing; in fact, examine the livid head of one who has died of asphyxia, or of apoplexy, you will see that it is especially in the skin and the cellular texture that the blood is arrested; that the muscles, the aponeuroses, exhibit besides the blood ordinarily found in them, only a small quantity of superabundant fluid, in comparison with what there is in the first organs. Remarks upon Injections. From all that has been said, it is evident, that fine injections, which form a convenient method of knowing the capillary system of an organ, cannot show which vessels of this system admit red blood, and which circulate only white fluids. In fact, the injected matter passes equally into each, and we cannot distinguish that, which in the living body is very distinct. In order to form a precise and accurate idea of the quantity of blood that enters each of the organic systems during life, it is indispensably necessary to dissect those systems during life. I shall frequently have occasion in this work, to make this truth felt, which appears to me to be of much importance in many respects. If a fine injection but partially succeeds, it almost always shows vessels that really exist, but which were not sanguineous during life. Even the coarse injections of our dissecting rooms frequently exhibit these phenomena, especially in the face, the neck, &c.; and much more so, if the matter injected is very delicate, and managed with much address. I cannot conceive why physiologists have always taken as an indication of the blood vessels, the state of injected organs; by opening any part of a living animal, they may clearly see how deceptive this method is. Injections are of no advantage except in the great vessels, in which the blood circulates in a mass by the influence of the heart; in the capillaries, they do not reach the precise point that exists in nature. I wish that in dissecting rooms, the pupils, after having dissected the arteries and veins, would finish their labours upon the vessels by the dissection of a living animal, for the purpose of seeing the quantity of blood that each system has in its capillaries; this knowledge is essential to the study of inflammations, fungous tumours, &c. Anatomical cabinets in which preparations are kept, are of no use in this respect; these preparations are more likely to deceive in proportion as the injections have succeeded well. III. Of the proportions which exist in the Capillaries between the Blood and the Fluids that differ from it. In the organs in which the blood, or the white fluids differing from it, alone enter, there can be no variety in the proportions; but the varieties are frequent in those where these fluids enter at the same time. In the serous, the dermoid, the mucous systems, &c. there are sometimes more, sometimes less small vessels filled with blood; the cheeks, of which I have spoken, are a remarkable example of this. The least emotion, the slightest agitation, or a motion a little too violent, accumulates, diminishes, and varies, in a thousand different ways, the quantity of blood in them. The whole exterior of the skin exhibits the same phenomenon, though less frequently. When this organ is irritated or excited at any point, it immediately reddens; it becomes white if it is compressed. Cold and heat uniformly produce analogous varieties, when the change from one to the other is sudden. All the mucous surfaces exhibit the same arrangement; see 10 11 12 the glans in the erection of coition, or in the flaccidity that succeeds it; the difference in the quantity of the blood that this external membrane contains, is very evident. Lay bare a serous surface; at first white, soon there will be numerous red streaks. If we could see the capillaries of the glands, I presume that we should find the quantity of blood variable in these vessels, and that during the time that the secreted fluids are poured out in abundance, their system would be more copiously supplied than at any of the time when it furnishes the materials of the secretions. Why are not the kidnies and the liver subject to the same varieties in the quantity of their blood, as the surface of the skin? When, by a violent motion, sweat pours out in abundance, and the external surface of the body looks more red, does it not indicate that the blood is there in a greater proportion? There are two things to be distinguished, however, upon this subject; it is only when the copious secretions arise from an increase of life, that a greater afflux of blood is supposed to take place in the glandular system. When this increased secretion proceeds from a want of vital energy, the blood is not in greater quantity in the gland. The same observation applies to exhalation; thus, in the above case, in the commencement of fever, &c. more blood enters the skin; but when the sweat arises from weakness, as in phthisis, &c. there is not this accumulation of blood in the capillary system. But this deserves a longer explanation. Different proportions of Blood in the Capillaries, according as the Secretions and Exhalations are active or passive. I call those exhalations and secretions active, which are preceded and accompanied by an evident development of vital forces; and those passive which exhibit an opposite phenomenon. If we examine the phenomena of the animal economy, it will be easy to see this distinction, which appears to me essential in diseases; now, in whatever organ you study it, you will always see every active exhalation or secretion preceded by a greater afflux of blood to the part; all passive exhalations and secretions present an opposite phenomenon. Let us begin with exhalations. 1st. Cutaneous exhalation is active from violent running, or a paroxysm of fever, as I have said, from the action of caloric upon the body, hard work, &c.; the skin is then more expanded and deeper coloured; more blood enters it, &c. This excitement of the skin makes it more fit to be influenced by external agents, and to influence in its turn all the other organs. It is the suppression of these transpirations which causes so many accidents in the animal economy. Observe, on the contrary, the complexion of the body in phthisical sweats, in those produced by internal suppurations, in those that are the effect of fear, in all those that are called colliquative, &c.; this complexion is more pale than in a natural state; it is not capable of being influenced, because its vital activity is then small, and its forces languish. 2d. In the exhalations of the serous surfaces, there are some that are essentially active; such is that of pus; for we shall see that the formation of this fluid upon these membranes is without any kind of erosion, that it flows evidently from the exhalants, instead of serum; very often even it flows at the same time. Nothing is more frequent, in fact, than the milky or purulent serum that is found in the peritoneum, the pleura, &c. whether the fluids are exactly mixed, or the pus floats in flakes in the serum. Now this active exhalation of serum or of pus, which appears to be here principally coagulated albumen, this exhalation, I say, is evidently preceded by a considerable accumulation of blood in the capillary system, an accumulation which constitutes inflammation, and without which exhalation cannot take place. Observe, on the contrary, serous exhalation, increased by the weakness that any organic disease gives to the serous membranes; to furnish this fluid, the blood is never accumulated in them in greater quantity. Open the membranous sacs, after the diseases of the heart, the womb, the lungs, the liver, the spleen, &c. you will find them full of water, but more diaphanous than usual, because they have received less blood. 3d. What I have said of the serous exhalations, must be said of the cellular; some of them are active, such as those of pus and the serum that sometimes accompanies it; others are passive, as the leucophlegmasia after organic diseases. The same observation is to be made as before; there is an accumulation of blood in the capillary system in the first kind, a diminution of this fluid in the second. Observe the fatty exhalation; a man in health who is very fat, has a rosy colour upon the integuments distended with fat, which indicates the abundance of blood in the capillary system. On the contrary, in certain cases of sudden corpulency after diseases, in that which is called false fat, and accompanies weakness, a general paleness corresponding with the fatty bloating, indicates the absence of the sanguineous fluid. 4th. Mucous exhalations present also an analogous phenomenon. I shall prove soon that the hemorrhages from the mucous surfaces are real exhalations; now some of them are active, a name which Pinel has given them in his Nosography; these are the nasal, pulmonary, gastric, uterine hemorrhages, &c. of young people and even of adults. All these hemorrhages are accompanied by a local increase of action, by greater heat, by a deeper colour of the mucous membrane, by the greater abundance of blood in the capillary system. Who does not know, that Galen predicted a hemorrhage from the redness which he saw upon the nose and the eye of the patient? On the other hand, observe the hemorrhages of the mucous surfaces, which take place after long diseases, hemoptysis, which terminates the diseases of the heart, hematemesis, the effect of organic derangement of the liver, hemorrhages from the intestinal canal, so frequent at the end of all the long organic diseases of the abdomen, &c. nasal hemorrhages in certain low fevers, those which take place in scurvy from the different mucous surfaces, the gums especially, &c. all these hemorrhages, which are truly passive are not accompanied by this preliminary sanguineous congestion in the capillaries, by this increased activity of vital action; it might be said that it is the blood, which transudes, as in the dead body, through the pores, that have not power to retain it. This distinction is so true, that without making a theory of it, physicians conform to it in their practice. We bleed to arrest an active hemoptysis, but would you bleed to stop that which comes on in the chronic diseases of the thorax? The same observation applies to all the hemorrhages; they require means wholly opposite, according as they 13 14 15 16 are active or passive; a remark moreover that is applicable to all diseases that have increased exhalations or secretions, whatever may be their seat. It is not the phenomenon that we are to resist, but the cause that has produced it. We diminish the forces, when serum is accumulated in the thorax, from a pleurisy; we increase them, when it accumulates from a disease of the heart, the lungs, &c. What I have just said of exhalations applies to secretions. The mucous glands pour out a greater quantity of fluids in two ways, sometimes from irritation, sometimes from the want of force. When this happens in the intestines, there results from it in the first case a diarrhœa from irritation, in the second a colliquative one. Now it appears that the blood enters the gland in greater abundance in the one than the other case. Its increase takes place undoubtedly in most acute catarrhs, in which there is active secretion of mucus; its diminution or at least its want of increase is not less sensible in many chronic catarrhs, in which we may consider the secretion as passive. We know that the abundance of urine, of bile, sometimes supposes an increased, sometimes a diminished action of the kidney and the liver. Is there not a superabundance of semen from excess of vitality, and an unnatural flow from weakness? All the secreted fluids have the same arrangement; now according to these two opposite causes of the superabundance of the secreted fluids, the capillary system of the glands is certainly penetrated with a different quantity of blood. Though the phenomenon be the same, the treatment in the diseases in which it is manifest, is as in the preceding cases, wholly opposite, according as the local increase or diminution of life concurs to produce it. Consequences of the preceding Remarks. From all that I have said, it is evident that in the organs whose capillary system contains in part blood, and in part different fluids, the proportion of the first to the others is infinitely variable; that a thousand causes in a state of health, as in that of disease, by bringing to the organ more or less blood, can fill more or less its capillary system. The trunks and branches that go to an organ, are they more or less dilated, according as the capillary system of this organ is more or less filled with blood? For example, when the mucous glands pour out fluid in the greatest quantity, are the neighbouring branches more full? Some experiments that I shall mention hereafter do not seem to prove it. IV. Of the Anastomoses of the General Capillary System. All that has been said evidently supposes a free communication established between all the parts of the capillary system; this communication is in fact clearly demonstrated by observation. When we examine a serous injected surface, of which the capillary system is full, we see that this system is a real net-work with fine meshes, and in which no vessel runs a distance of more than two lines, without communicating with others. The passage then, is constantly open between the portion that receives blood, and that which admits fluids differing from it. The same arrangement exists in the dermoid system, in the origins of the mucous, &c. and in general in all those in which the capillary system contains blood and white fluids. On the other hand, the organs in which we find only white fluids, evidently communicate with those that are near them, and in which there is blood; those in which blood alone flows, have the same arrangement. The capillary system must then be considered as a general net-work, spread throughout the body, which communicates on one side in every organ, and on the other from one organ to another. In this respect there is from the head to the feet a general anastomosis, a free communication for the fluids. It is in this way that we can conceive of the permeability of the body, and not from the cellular texture, in which the serous and fatty fluids alone stagnate. As the arteries enter the capillary system, and as the veins, the exhalants, the secretories, go from it, it is evident from this manner of considering the capillary system, that all these vessels ought to communicate with each other; that by pushing a fine fluid into the arteries, it should go out by the excretories, the exhalants, and return by the veins, after having gone through the capillary system; this is in fact what takes place. In this respect, a thousand ways are constantly open for the blood to escape from its vessels, which communicate thus everywhere without, and do not present any mechanical obstacle to the blood in their cavity, which life alone retains within the limits of its circulation. The oozings after death through the exhalants, the excretories and the veins, are so well known, so many anatomists have related examples of them, that I think it unnecessary to give them in detail here. We have seen, then, fine injections pour out upon the serous membranes, upon the pericardium, the pleura, the peritoneum, &c. transude upon the mucous surfaces, even upon the skin. We have seen them flow through the ureters, the pancreatic, biliary, salivary ducts, &c. Haller, in the article upon each organ, has not failed to relate examples of this sort, which prove the communication of the arteries with all the other vessels, by means of the capillary net-work. What anatomist has not sometimes made even coarse injections return by the veins? The communication of these vessels with the arteries, through the capillary system, is now an anatomical axiom. At one time, it arrested much attention. It has been asked, if there was any thing intermediate between the arteries and the veins; inspection proves that the capillary system alone is there. Hence it is necessary to represent the capillary system as a kind of general reservoir, in which the arteries enter on one side, and from which go out on the other side, in all the organs, the nutritive exhalants, in some, certain particular exhalants, as those of the sweat, the lymph, the fat, &c. in others the secretory vessels, &c. It is a common reservoir, if I may so express myself, in which the red blood enters, and from which the black blood, the exhaled, the secreted fluids, &c. go out. 17 18 19 This idea is not hypothetical; the injections of which I have spoken are the most evident proof of it. Let it not be said that it is a transudation after death, analogous to that of the bile through the gall-bladder: if it were so, not only the fine fluids injected would go out by the excretories and the exhalants, and return by the veins; but in oozing through the pores, they would fill the whole cellular texture. On the contrary, nothing escapes into the cellular texture, around the vessels by which the injection passes; there is then a continuity of tubes from the artery which has received the fluid, to the excretory, the exhalant, or the vein which transmits it. These are the communications of the capillary system that explain how the skin becomes livid on the place on which a dead body has for a long time lain, as on the back, for example; how by turning a dead body, so that the head may hang down, it becomes full of fluid; how, on the contrary, by placing upright the body of one dead from apoplexy, asphyxia, &c. the capillary system of the face is freed in a great measure from the blood it contained; how an erysipelas disappears on a dead body, when the blood, arrested during life on a part of the skin, by the vital action, is spread after death to all the surrounding parts; how every kind of analogous redness of the skin, and even of the serous surfaces, disappears because the blood goes by the communications of the capillary system to the neighbouring organs. During life the tonic action retains the fluid in a determinate part; abandoned to its gravity, and other physical causes, after death, it soon disappears from the part in which it was accumulated, on account of the innumerable communications of the general capillary system. I would observe to those who examine dead bodies, that these considerations are very important. Thus we must not judge of the quantity of blood which penetrated the inflamed peritoneum or pleura, by what is seen twenty-four hours after death; local irritation was a permanent cause that fixed the blood in the part; this cause having ceased, it escapes from it. A serous membrane may have been very much inflamed during life, and yet exhibit almost its natural appearance after death; as it is in erysipelas. I should have been often tempted from opening dead bodies, to deny the existence of an affection which had been real. The same remark applies to the inflamed cellular texture, the mucous surfaces, &c. Examine a subject that has died of angina, which during life gave the deepest red colour to the pillars of the velum pendulum pelati, to the velum itself and the whole pharynx; after death, the parts assume nearly their natural colour. I would observe that in this respect it is necessary to distinguish acute from chronic affections. In the chronic inflammations, for example, of the pleura, of the peritoneum, &c. the redness continues after death, because the blood is combined, as it were, with the organ; it makes a part of it, as it makes a part of the muscles in a natural state. So the chronic affections of the skin, of the mucous surfaces, retain after death nearly the same blood, that they had during life; whereas in acute affections, the blood retained for a time by irritation, escapes when life has ceased, upon which this irritation depended. These principles can be applied to many diseases; I repeat it, they are of great importance in examining bodies. The neglect of them has often led me into an error, upon the degree and even the existence of acute inflammations, of which the organs that I examined had been the seat. V. How, notwithstanding the general communication of the Capillary System, the Blood and the Fluids differing from it, remain separate. Since in the dead body, and consequently during life, there is in the capillary system no organic obstacle to the communication of the fluids through its small branches; since the general net-work that these vessels form is everywhere free, how does it happen that the blood does not pass into the part destined to the white fluids? how is it that these do not enter where the blood is to circulate? Why does not this fluid go out by the exhalants and the excretories, since these tubes communicate with the arteries by the anastomoses of the capillary system? This depends wholly upon the relation which exists between the organic sensibility of each part of the capillary system, and the fluid that it contains. That which carries the blood, finds in all the other fluids irritants that make it contract at their approach; and reciprocally, where the other fluids belong, the blood would be a foreign fluid. Why does the trachea admit air, and reject every other fluid? Why do the lacteals choose only chyle from the contents of the intestines? Why does the skin absorb certain substances, and repel others, &c.? It all depends upon this, that each part, each portion of an organ, every organic particle, has its own sensibility, which is in relation only with one substance, and repels others. But as this kind of sensibility is remarkably subject to vary, its relation to substances foreign to the organ changes also; thus the part of the capillary system which rejected blood, admits it at the moment when its sensibility has been increased. Irritate a part of the skin, it reddens in an instant; the blood flows there; while the irritation continues, it remains; when it ceases, it disappears. Whatever be the external means which raise the cutaneous or mucous sensibility, we observe the same phenomenon. We can in this way bring more or less blood into some parts of the capillary system. Bring the hand to the fire, the heat exalts the sensibility of its system, more blood enters it; take it away, this property resumes its natural type, and the blood is brought back to its ordinary quantity. The internal organs which are subjected less to the causes of excitement, have less varieties in their capillary system; yet, however, there are many, and all arise from the same principle. A series of organized tubes are unlike an assemblage of inert ones. These last require mechanical obstacles to prevent the communication of fluids with each other; where there is a communication between the tubes, there is a communication in the fluids. On the contrary, in the living economy, it is the peculiar vitality with which each tube is animated, which serves for an obstacle and a limit to the different fluids; this vitality performs the part of different machines that we place in the communicating tubes, to separate them from each other. Every organized vessel is then truly active; it admits or rejects fluids which enter there, according as it is able or not to support their presence. 20 21 22 Disproportion of capacity has nothing to do with this phenomenon; a vessel may have mere than four times the capacity of the particles of a fluid, and yet refuse to admit them, if this fluid is repugnant to its sensibility. It is in this point of view that the theory of Boerhaave has a great defect. At the period in which this physician wrote, the vital forces had not been analyzed. It was necessary to employ physical forces to explain vital phenomena; hence it is not astonishing that all his theories are so incoherent. In fact, theories in the vital phenomena borrowed from physical forces, exhibit the same inadequacy, as those would in the physical phenomena borrowed from vital laws. What would you say, if in explaining the motion of the planets, rivers, &c. they should talk of irritability and sensibility? you would think it absurd; it is equally absurd, in explaining the animal functions, to talk of gravity, impulse, inequality of the capacity of the tubes, &c. Observe, that the physical sciences made no progress until they analyzed the simple laws that preside over their innumerable phenomena. Observe also, that medical and physiological science was not accurately explained, until the vital laws were analyzed, and it was shown that they were everywhere the principles of the phenomena. See with what ease all those of the secretions, exhalations, absorptions, inflammation, capillary circulation, &c. are referred to the same principles, flow from the same data, by deriving them all from their real cause, the different modifications of the sensibility of the organs which execute them. On the contrary, see how each presented a new difficulty, when the mechanical causes were employed to explain them. From what has been said, it is then evident, that in the innumerable variations of which the fluids of the capillary system are susceptible, in the different portions of the system which they fill, there is always antecedent variations in the sensibility of the vascular parietes; these varieties produce the first. It is especially in the capillary system and its circulation, that the variations of the organic sensibility of the vessels produce varieties in the course of the fluids; for as I have observed, in the great arterial and venous trunks, in the heart, &c. the fluids are in too large masses, and they are agitated by too strong a motion, to be thus immediately subjected to the influence of the vascular parietes. Thus when nature wishes to prevent the fluids from communicating in the trunks, it places among them valves, or other analogous obstacles, which become useless in the capillary system. Though the anatomical arrangement be the same in the living and the dead body, there is then a very great difference in the course through the capillary system, in one and the other. Push, into the aorta of an animal in whom you destroy life by opening this artery to fix in it a syringe, different fine fluids; you will never see them fill the capillary system, pour out by the exhalants, the excretories, &c. as when the subject has been some hours deprived of life. The organic sensibility inherent in the parts repels the injection; it can only circulate in the great trunks, in which there is a large space. I have injected, with other views, a great number of times, fluids by the arteries and the veins; now, the capillary system is never filled with these fluids; they circulate only in the great vessels, when the animal can bear them. Mr. Buniva has also made comparative experiments with injections upon living animals and those deprived of life; he has experienced in the first a resistance which he has not found in the other; now this resistance is in the capillary system, whose vessels refuse to admit a fluid to which their organic sensibility is not accommodated. VI. Consequences of the preceding principles, in relation to Inflammation. From what has been said thus far, it is easy, I think, to understand what takes place in the inflammatory phenomena, considered in general. If a part be irritated in any manner, immediately its organic sensibility is altered, and increased. Without previous connexion with the blood, the capillary system is then placed in relation with it; it as it were calls it there; it flows there and remains accumulated until the organic sensibility returns to its natural type. The entrance of the blood into the capillary system is then a secondary effect of inflammation. The principal phenomenon, that which is the cause of all the others, is the local irritation which has changed the organic sensibility; now this local irritation may be produced in different ways; 1st, by an irritant immediately applied, as a straw upon the conjunctiva, cantharides upon the skin, acrid vapours upon the mucous surface of the bronchia or the nasal cavities, atmospheric air upon any internal organ laid bare, as we see in wounds, &c.; 2d, by continuity of organs, as when a part of the skin, of the pleura, &c. being inflamed, those that are near it are also affected, and the blood flows there, as when one organ is diseased, that which is near it becomes so by the cellular communications; 3d, by sympathies; thus the skin being seized with cold, the pleura is sympathetically affected; its organic sensibility is increased, the blood immediately enters it from every part. When this property is raised in one of these three ways in the capillary system, the phenomena that result from it are the same. For example, when in the pleura it is raised because the air is in contact with this membrane, because the lungs that it covers have been first affected, or because coin has seized upon the skin in sweat, the effect is nearly analogous, as it respects the entrance of the blood in the capillary system. It is then the change that takes place in the organic sensibility, that constitutes the essence and the principle of the disease; it is this change which makes a pain more or less severe soon felt in the part; then the sensibility that was organic, becomes animal. The part was before sensible to the impression of the blood, but did not transmit this impression to the brain; then it transmits it, and this impression becomes painful. Irritate the healthy pleura in a living animal; it does not suffer; irritate it on the contrary during inflammation, and it gives signs of the most acute pain. Who does not know that most often and almost always, a pain more or less acute is perceived in the part, some time before it 23 24 25 26 becomes red? Now this pain is the indication of the alteration that the organic sensibility undergoes; this alteration exists some time, often without producing an effect; this effect, which is especially the afflux of blood, is subsequent. It is the same of heat. I shall say hereafter how it is produced. It is sufficient now to show that it is, like the passage of the blood in the capillary system, only an effect of the change that has taken place in the organic sensibility of the part; now this is evident, since it is always consequent upon this change. There happens then in inflammation exactly the reverse of what Boerhaave thought. The blood accumulated according to him, in the capillary vessels, and pushed à tergo by the heart, as he termed it, was truly the immediate cause of the affection, whereas, from what I have said, it is only the effect. If we reflect a little upon the innumerable varieties of the causes which can alter the organic sensibility of the capillary system, it will be easy to understand of what infinite varieties inflammation is susceptible, from the momentary blush that comes and goes in the cheeks, to the most serious phlegmon and erysipelas. We might make a scale of the degrees of inflammation. By taking the cutaneous, for example, we should see at the bottom the redness that arises and disappears suddenly by the least external excitement upon the dermoid system, which we can produce at will, and in which there is only an afflux of blood; then those that are a little more intense, which occasion cutaneous efflorescences of some hours, but without fever; then those that continue for a day, with which there is some fever; then erysipelas of the first order; then that which is more intense, and which gangrene soon terminates. All these different degrees do not suppose a different nature in the disease; the principle of them is always the same; there is always, 1st, an antecedent increase of organic sensibility, or alteration of this property; 2d, afflux of the blood only if the increase is not great, afflux of the blood, heat, pulsation, &c. if it is. As to fever, it is a phenomenon common to every severe, acute local affection; it appears to depend on the singular relation which connects the heart with all parts; it has nothing peculiar in inflammation, but the particular modification it receives from it. The afflux of the blood in an irritated part takes place in inflammation, as in an incision. In this the divided point has been irritated by the instrument; soon the whole blood in the neighbourhood flows there and escape...