Chapter VII: Section II (2)

In the organized systems, the cellular texture at first accompanies and surrounds, in their whole course, the vascular and nervous branches which enter into their composition; then it unites together the different homogeneous parts of each of them. Each fasciculus of a muscle, every muscular fibre, every nervous filament, every portion of aponeurosis and ligament, every glandular particle, &c. are surrounded with a sheath, a particular cellular layer, which in relation to its parts, is destined to the same uses that the greater covering of which we have just spoken, performs for the whole organ. Thus the life of each fibre is insulated by this layer, which, like that of the whole organ, forms around it a kind of atmosphere, destined to defend and protect it, but which can, however, like the general layer, and even more than that, because the parts are nearer to each other, be the means of the communication of diseases from one fibre to another. The motion of each of these fibres is peculiarly favoured by the cellular texture; thus the organs, which, like the muscles, have a very apparent motion in each of their parts taken separately, are capable by means of it of a much greater internal contraction, than those which, like the tendons, the ligaments, and the glands, have no sensible motion but that which is communicated to them.

The internal cellular texture of each organ has but little of the vital character which distinguishes that organ; it preserves almost all its general properties; it is, in the structure of different parts, the medium which unites without resembling them. We see that it is insensible in the nerves, without contractility in the muscles, or powers of secretion in the glands. It is often affected without the participation of the organ. In many organic affections of the liver, we meet with steatomatous tumours, which give this organ a raised and uneven form, and which, occupying only the cellular texture, leave untouched the glandular texture, which secretes as usual the bile, which undergoes no alteration in its course. It is remarkable, that these tumours, oftentimes of enormous size, should exist without injuring the secretion of bile. They may be compared with those not less remarkable in the lungs in phthisis, in which, however, respiration is performed almost the same as in health.

There are many organs, in which the cellular texture is hardly apparent, because their structure is so compact; some authors have even denied the existence of it in them. But in many of these organs, maceration, by filling in an insensible manner the fibres with water, parts them by degrees, and makes apparent the cellular texture which separates them, as we see especially in the tendons, in the fibrous membranes, &c. Ebullition, which takes from some their nutritive substance, for example gelatine, leaves a membranous residue which is evidently cellular. In all, even the bones and cartilages, the production of fleshy points, or granulations, which, as we shall see, are essentially of a cellular nature, proves the existence of this internal texture, of which they are only the elongations. The same may be said of the bones becoming soft, and fleshy, and of fungous tumours of the other systems, diseases in which this texture becomes very apparent, because the organ loses by them its compact structure, and takes one that is more loose and spongy, and which exposes that which is placed in the interstices of the fibres.

ARTICLE SECOND.

OF THE CELLULAR SYSTEM, CONSIDERED INDEPENDENTLY OF THE ORGANS.

After having considered the cellular system in relation to the organs, let us consider it separate from all the parts that it covers and penetrates, in order to represent it as a body continued on all sides, found every where in the interstices of the organs and being analogous in this point of view to almost all the other primitive systems. Let us trace it in the head, the trunk, and extremities.

I. _Of the cellular system of the head._

The cranium and face differ extremely as it respects the cellular texture; it is found in very small quantity in the first, and in great abundance in the second.

_Cellular texture of the cranium._

The interior of the cranium has but very little cellular texture; it is even apparently destitute of it. If, however, we raise the tunica arachnoides, where the vessels enter and where the nerves go out, we shall find a small quantity, which is remarkable for its delicacy and transparency. The pia mater is principally formed by this texture, and the texture of this membrane appears to be continued with that of the brain; this, however, is extremely hard to be demonstrated; it is not proved by maceration, and it is scarcely seen except in fungous tumours.

The communications of the cellular texture of the interior of the cranium are very numerous.

1st. In front it enters the orbit by the optic foramen and the sphenoidal fissure; hence the redness and heat of the eye in paraphrenitis,[5] the influence of which is propagated by these communications, as well as by the continuity of membranes. It enters the nostrils by the foramina in the cribriform plate; to this perhaps we may attribute the weight, and pain of the head in coryza.

[5] The word paraphrenitis is meant probably to designate the inflammation of the meninges of the brain, though this term is not usually employed by English writers; but the word used by the author might be translated inflammation of the diaphragm, which certainly is not his meaning. _Tr._

2d. Below, the numerous foramina of the base of the skull effect communications between the face and the cerebral cellular texture, and between it and the top of the pharynx, the zygomatic furrow, &c. In many cases in which angina is attended with pain, and heaviness in the head, vertigo, &c. I am convinced that it is in a great measure owing to these communications, though oftentimes it may be wholly sympathetic.

3d. Above and behind, the cerebral texture is continued with that of the corresponding parts of the head, by the numerous but small openings in the sutures; it accompanies the vessels that go from the dura-mater to the pericranium, and it becomes probably sometimes the means of communication, that is so frequently observed between these two membranes, when one is inflamed; hence the sudden affection that frequently takes place of the dura mater, tunica arachnoides, &c. from a stroke of the sun upon the integuments of the cranium, &c.

The cellular texture, though more abundant on the outside of the cranium, is not found in great quantity there, no doubt because the muscles are so few and thin. Its communications with the face are evident, especially upon the forehead; as a consequence of erisypelas of the cranium, nothing is more common than to see the eye-lids receive the pus that is formed, and which often accumulates in these moveable veils, so as to occasion considerable deposits. It is by these communications also that serum is deposited there, and blood extravasated. Behind and upon the sides, the communications of the cellular texture of the cranium are also very evident.

_Cellular texture of the face._

It is very abundant in every part. The orbits are filled with it; the excavation of the cheeks, that is bounded by the buccinator and masseter muscles, the zygomatic and malar bones, contain much of it: all the neighbouring parts of the tongue are furnished with it. The nasal cavities only and their sinuses, which a mucous surface covers, that is almost immediately attached to the bone, have but a small quantity of it.

The facial cellular texture contributes to the beauty and harmony of the countenance, the features of which, examined closely, show that the muscles draw in an unpleasant manner across the skin, when there is no fat, and consequently that there is too great a depression. In an opposite state, there is a kind of bloating that is disagreeable; a middle state is the most favourable to the beauty of the face. This texture is almost wholly disconnected with expression, which is effected by the muscles. Thus the different passions are delineated with nearly the same features upon a fat and a lean face. Only these features are less marked in the first than the second, because in the last more wrinkles are formed than in the other, by the contraction of the same muscles.

The cellular texture is in greater or less quantity in the face in different people. Every one knows that some are always thin in this part, who are fat in the rest of the body. From the dissection of the bodies of such persons, I have found that it arises from the small quantity of cellular texture it contains in proportion to the other parts. In other individuals, there is an opposite state, a fulness of the face with a lean body, a striking contrast, and which arises without doubt from a cause opposite to the first.

It is to the greater proportion of cellular texture, much more than to the development of the muscles, that must be attributed the evident thickness of certain parts of the face, in different species of the human race, that, for example, of the lips and the alæ of the nose in negroes, &c. From the same cause arises the variety in thickness in the great and small labia pudendi.

The principal communications of the facial cellular texture are made with the neck by the sub-cutaneous portion of this texture, by that which accompanies the vessels, and particularly in the triangular space at the superior part of which is situated the parotid gland. Thus, from deposits made upon the lateral parts of the face, effusions of pus take place that often extend to the neck. In emphysema, the air of which comes from the chest, after the neck is swelled, the air passes to the face principally by the sides. There are still great communications of cellular texture between the neck and the face, by the spaces between the muscles that are attached to the base of the tongue.

II. _Cellular system of the trunk._

It varies in its proportions, as we examine the regions of the spine, the neck, the chest, the abdomen, and pelvis.

_Vertebral cellular texture._

I so call the cellular texture which is found in the neighbourhood of the spine, and in the vertebral canal.

In the cavity of this canal, there is but very little of it. Between the tunica arachnoides and the medulla oblongata, between the nervous elongations that go from the last, and the sheaths of the arachnoides that accompany them, we see some filaments that follow the course of the vessels, and contribute to the formation of the pia mater. There is none of this texture between the arachnoides and dura mater. Below this, between it and the vertebral canal, in the places where it does not adhere, there is more of it, especially below, where it is very loose, and always covered with a fluid that is often reddish.

On the outside of the spine, we see, behind, many muscles and but little cellular texture in proportion; thus, depositions in this part are much more rare and much less liable to spread than elsewhere, a circumstance which arises also from this, that the muscles being very compact in the vertebral canals, keep in a state of depression the cellular texture that separates them.

This texture is on the contrary very abundant along the whole course of the anterior part of the spine, in the neck, where it accompanies the carotids, in the thorax and abdomen, where it follows the course of the aorta, the great trunks which go from it, the vena cava, azygos, &c. There is no part of the animal economy, more frequently exposed to different collections of pus, than this. Nothing is more common than to see depositions that are formed at the anterior part of the thorax and abdomen, projecting at the groin by a channel which we discover by the examination of bodies. It is principally by these cellular communications, and by those which are beneath the integuments, that the superior parts correspond with the inferior, and vice versa.

_Cervical cellular texture._

The neck, which is very muscular, has much cellular texture, besides that which belongs to the vertebral column. It is especially in the lateral parts, where the lymphatic glands are situated, that this texture is remarkable. In the space between the sterno-cleido-mastoideus and trapezius muscles, where the brachial nerves arise, and where the vessels pass that go from the thorax, there is a great quantity of it. It communicates with that of the thorax, by the large opening that is found at the superior part of this cavity; hence it happens, that when the cells of the lungs are ruptured, the escaped air occupies first the chest and then the neck, and hence also the facility with which we produce the same phenomenon by forcing air beneath the pleura of a dead body, &c.

The cellular texture of the neck communicates also with that of the superior extremities above and below the clavicle. Hence why the neck and consequently the chest, are filled with air, water, and other fluids that are forced into the sub-cutaneous and intermuscular texture of these extremities.

_Pectoral cellular texture._

In the pectoral cavity, it is upon the median line that the cellular texture is especially found; it is abundant in the space formed by the duplicature of the mediastinum; the neighbourhood of the pericardium is supplied with it, particularly around the great vessels, which it accompanies a short distance; the rest of the thorax, occupied by the lungs, contains much less of it.

The pectoral texture communicates with the abdominal, 1st. by the different openings of the diaphragm, by that of the aorta, and particularly of the œsophagus; that of the vena cava being too closely united to that vessel, to permit these communications easily; 2d. by the opening of the diaphragmatic fibres, especially by the triangular space, through which those pass that are attached to the ensiform cartilage; hence the passage of the deposits from the thorax to the abdomen. Desault mentions a purulent collection, first formed in the neck, and which by the anterior mediastinum, became prominent just above the abdomen. Hence the facility with which the pleura particularly on the right side receives the influence of diseases of the peritoneum, when this is diseased on the convex surface of the liver which always keeps its place, whilst by the motions of the stomach and the spleen, that which covers those two viscera, which are constantly changing their situation, has a much less decided influence upon the left pleura.

The cellular communications of the chest take place also from the interior to the exterior, by the interstices between the intercostal muscles, but they are not very evident, as these interstices are very small; thus the diseases of the breast have rarely any influence out of this cavity; this happens however when in dropsies and chronic inflammations of the pleura, the pectoral integuments have an adhesion to the diseased side.

The exterior cellular texture of the chest, is very abundant above; it there surrounds the breasts and contributes in part to those rounded forms that delight us in women, and those prominent ones which we admire in a well formed man. We see it in great quantities under the pectoral muscles; below it diminishes in a very evident manner.

_Abdominal cellular texture._

The abdomen contains, in proportion a little more cellular texture than the thorax. In the interior of this cavity, this texture is found collected in the places where the great arteries and veins enter the gastric organs, as in the fissure of the liver, the mesentery, &c. It is not abundant between the peritoneum and the anterior and lateral parietes of the abdomen, but it is so on the posterior part of this membrane, particularly about the kidnies. This interior texture communicates at first with that of the pelvis, all around the peritoneum, then with that of the lower extremities, by different openings, by the inguinal ring and especially by the crural arch. The first of these openings establishes also a cellular correspondence between the abdomen and genital organs, particularly in man. We can easily prove these communications by injecting a fluid into the abdominal cellular texture of a dead body. This fluid goes spontaneously to the inferior extremities, whilst it requires a long continued force to drive it to the superior. All practitioners know, that there is hardly any case of ascites, in which the lower extremities are not swelled, while the superior are unaltered. It is then with the abdominal cellular texture, that that of the inferior extremities has a particular relation, as it is with the pectoral that that of the superior corresponds, as has been observed by Bordeu and Portal. It is to be remarked however, that the first are affected much more easily in the diseases of the abdomen, than the second are in those of the chest.

_Cellular texture of the pelvis._

There are but few parts in which the cellular texture is more abundant than in the pelvis. Around the bladder, rectum and womb there is a great quantity of it, it is found no where more abundantly. This appears to me to be the cause of it; that, as these three organs are subject to great dilatation, and as the osseous parietes of the pelvis cannot yield to these dilatations, like the abdominal parietes, it is necessary that something should so act, that in whatever state the preceding organs may be, the cavity of the pelvis should be always filled. If the motions of the brain alternately increased and diminished the size of this organ, the bony cavity of the cranium would have been lined without doubt with cellular texture.

Besides we know the effect of this large quantity of cellular texture in the pelvis, in deposits which take place in the neighbourhood of the anus, in infiltrations of urine which accompany ruptures of the urethra and bladder. The facility with which pus and urine spread themselves in this part and the mischief they occasion, are well known.

This texture communicates with that of the inferior extremities by the ischiatic notch, by the arch of the pubis, &c. Different authors mention, that effusions of pus and urinous infiltrations extend downwards by these communications. We can fill the pelvis with air, by blowing this fluid into the inferior extremities, especially in their intermuscular texture.

The exterior of the cavity of the pelvis has also much cellular texture, less however behind than upon the sides, but in front around the genital organs of man as well as woman, there are large masses, particularly upon the great labia and the dartos.

III. _Of the cellular system of the extremities._

In the superior and inferior extremities, the quantity of cellular texture decreases from the superior to the inferior part. Around the two superior articulations, it is very abundant. The hollow of the axilla, in which the head of the humerus is situated, and which is spacious, is almost entirely filled with it. The groin has also considerable, though less than the axilla. The arm and the thigh have between their muscles large interstices that are cellular. At the elbow there is a smaller proportion than at the ham, whose deep cavity has a considerable quantity; an arrangement that is consequently the reverse of that of the axilla compared with that of the groin.

In the fore arm and leg, the muscles approach each other in a sensible manner; their cellular layers are much more compact, the whole cellular system is less abundant.

Towards the inferior part of these two portions of the limbs, where almost every thing on the hand and foot are tendinous and fibrous, the cellular texture diminishes still more, and becomes in proportion to the motions, hardly sensible. However, the foot, especially on the sole, contains much more than the palm of the hand, where we see but little.

This successive decrease of the cellular texture of the limbs is adapted to the uses of their different parts. In fact the extent of motion that exists above, requires in the muscles a laxity which they borrow from the quantity of cellular texture that surrounds them. Below, the multiplicity and at the same time the limited extent of the motions of the hand and the foot, of the hand especially which is destined to adapt itself to the form of external bodies, require in the organs of these two parts a close juxta-position, for which they are indebted to the small quantity of cellular texture that exists there.

ARTICLE THIRD.

OF THE FORMS OF THE CELLULAR SYSTEM, AND THE FLUIDS IT CONTAINS.

I. _Of the cells._

The general conformation of the cellular texture is not the same every where. The interstices or cells between the different layers, are more or less wide; their size is remarkable upon the eyelids and the scrotum, and in general where there is no fat, or where it is in small quantity. Moreover the capacity of the cells is extremely variable; nothing definite can be determined upon this point, as they are capable of contraction and expansion. When fat and serum fill them, they are double, triple or even quadruple what they are when they are empty. It is the variation in the size of the cells of the system of which we speak, which constitutes all the difference of the general size of the body in corpulency or emaciation; in each state the size of every nervous, tendinous fibre, &c. remains nearly the same, and the cellular system only varies. There is the same variety in leucophlegmasia compared with the ordinary state of the body.

The figure of the cells is so variable, that we cannot describe them in a general manner. Round, quadrangular, hexagonal, oval, are found mixed together. The best way to see these, is to freeze an infiltrated limb; numerous little icicles are then formed, and show by their form, that of the cells which they filled. Artificial emphysema is also a good way; I have often determined by it in our slaughter houses where they blow meats, the forms of the cells. The injection of melted gelatine may also be employed; but the results are less certain, because in going from one cell to another, it breaks the texture; and moreover after it is hardened, it is difficult to separate each portion contained in each cell.

All the cells communicate; so that the cellular texture is really permeable throughout the whole extent of the body, from the feet to the head. This permeability is proved, 1st. by emphysema spontaneously produced; 2d. by that which is artificially produced in a living animal, by blowing air under any portion of the cutaneous organ, an operation which affects neither the life or health of the animal, though oftentimes the whole of the body is bloated. We know that some beggars make use of these means without danger, for the purpose of exciting compassion. 3d. If one or two punctures are made in a dropsical limb, it is sometimes wholly emptied in this way. 4th. Oftentimes this happens from ruptures taking place spontaneously in limbs of this kind. 5th. Pressure made upon them, makes the fluid ascend or descend, according to the part upon which it is made. 6th. A rupture of the bladder or the urethra produces an urinous infiltration, which sometimes extends even to the sides of the chest. 7th. The injection of any fluid into the cellular texture of a dead body, produces an artificial leucophlegmasia.

The permeability of the cellular texture has been much exaggerated, or rather it has been presented under a point of view different from that in which it is shown by nature. It is thus that many physicians, thinking that it could be pervaded indifferently by all the fluids of the animal economy, have believed that these fluids formed there, currents in different directions more or less irregular. Thus the sweat has been considered as the transmission by the skin of the albuminous fluid of the cellular texture, which, according to some moderns, is drawn out with the caloric that is constantly disengaged. They have thought, also, that the permeability of this texture would explain the rapid passage of drinks to the bladder. They have explained by it too, the promptness with which sweat is produced by warm liquors, &c.

All these theories, that examination never proves, are repugnant to the known laws of our economy, laws which show us the fluids constantly circulating in the vessels, in consequence of the vital forces, of organic sensibility and contractility which they possess, and not as being extravasated to move irregularly in the cellular texture. Moreover, I have never found any portion of drink in the cellular texture of animals immediately after they have taken it. I have tried many of these experiments upon dogs, after having deprived them for some time of drink, that they might drink the more. The cellular texture in the neighbourhood of the stomach and intestines, that especially which, placed behind the mesentery, communicates with the pelvis where the bladder is situated, having been attentively examined, did not appear to me to contain any fluid; it was analogous to that of the other parts of the body. Besides, as we shall see hereafter, these phenomena can be explained in a very natural manner.

The cellular texture is permeable, then, only to fat and lymph; and yet it appears that but little use is made in an ordinary state of this permeability by these two fluids, which remain in their cells, until absorption takes them up. We do not see them pass from one to another; they are stagnant, if we may so say. It is only in serous infiltrations, in effusions of pus, in one word, in a morbid state, that the cellular permeability becomes apparent. We can only consider, then, the cellular texture as the reservoir, in which are formed the serum and the fat. After death the cellular texture is every where penetrated by fluids, which pass not only across the communicating openings of its cells, but also through the pores which it has, like all the solids; hence the infiltration of the integuments of the back, in dead bodies that have been laid upon it for a length of time; hence also the passage of the bile through the texture, which separates the gall bladder from the duodenum, and by which means this intestine is discoloured, &c. &c. But these phenomena have nothing in common with those that take place in the living body.

II. _Of the serum of the cellular membrane._

The first of the two cellular fluids appears to be the same as that which is elsewhere furnished by the exhalants and taken up by the absorbents. The first deposit it in the organs, the second carry it from them. Thus when we expose to the air condensed by cold any part of the cellular texture of an animal recently killed and still preserving its heat, we see a vapour arise which results from the solution of the serum in this air, a vapour perfectly analogous to a cloud that transpiration and respiration produce in winter, or even to that which arises from any aqueous fluid, exposed hot, with a large surface to the action of fresh air. When the atmosphere is warm the solution takes place in the same way, but as the vapour is not condensed, there is no apparent cloud.

The cellular serum varies in quantity in the different regions. Where there is no fat, as in the scrotum, the eye-lids, the prepuce, &c. it appears to be a little more abundant than elsewhere. We see also that these parts are much more disposed to different infiltrations. In this respect, the scrotum holds the first rank; then come the eye-lids, afterwards the prepuce, &c. Observe upon this subject, that the cellular texture exterior to the mucous surfaces, the arteries, the veins, and excretories, a texture which by the absence of fat resembles the ordinary, differs from it, however, in this, that serum is never effused in it.

We cannot judge of the quantity of cellular serum by observations made upon the dead body, in which the laxity of the parts permits a transudation of the fluids from all the vessels that pass through the cellular texture, and which then enter the cells. To estimate accurately the cellular moisture, I made an animal first emphysematous below the skin; I made a large incision into this; little blood only escaped, because the swelling separated the vessels from the course of the knife. By these means, the cellular texture being laid open, I have often been convinced that there was much less serum in this texture than we commonly suppose. I have not observed, that during digestion, after sleep, and whilst much sweat is exhaled by the cutaneous organ, three circumstances under which I have repeated these experiments, that the cellular serum is increased or diminished in a sensible manner. This fact coincides with what I have stated in my Treatise on the Membranes, upon the fluid that lubricates the serous surfaces, and the proportion of which is almost always nearly equal.

We know that in leucophlegmasia, the quantity of cellular serum is much increased; that it disappears in inflammation, &c.

The nature of this fluid appears to be essentially albuminous; experiments made upon that of leucophlegmasia show that there is albumen in it; but has not disease then altered its nature? To be satisfied in this respect, I first made a dead animal emphysematous, for the purpose of distending the cells, and to make the alkohol, which I afterwards injected by a syringe, enter them more easily. Some minutes after, the skin having been removed, the subjacent texture presented here and there different whitish flakes. By immersing in diluted nitric acid the cellular portion of the scrotum of a sound body that is dead, or which is better, a portion taken directly from a living animal, we can observe the same thing. It appears, then, that in health as well as disease, the albumen is one of the essential principles of the fluid of the cellular texture. I have taken much of this texture from the scrotum of many bodies, so as to have it separate from the fat, and I have made it boil in about the same time as nearly the same quantity of tendinous substance; at the moment of ebullition, much whitish froth rises upon the water, but little appears in that which contains the tendons.

Is the nature of the cellular fluid the same as that of the lymph that circulates in the absorbents? It cannot be doubted but that these vessels take off this fluid in the cells; it is possible that it is mixed with other substances, those especially that come from nutrition, which alter its nature. Chemical analysis is defective upon this point.

III. _Of the cellular fat._

The fat is the second of the fluids for which the cellular texture serves as a reservoir.

_Natural proportions of the fat._

Very abundant under the skin, around the serous surfaces, the organs of great motions, &c.; it is wanting, as we have said, upon the penis, the prepuce, the scrotum, &c. under the mucous surfaces, around the arteries, the veins, &c. Examined in the interior of the organized systems, the fat varies in quantity. There is none between the interstices of the arterial and venous coats. The lymphatic glands do not appear to contain any. The brain and spinal marrow are destitute of it. It is always found in the intervals of the nervous fibres; it is not often very evident; but in dissecting them, an unctuous substance escapes, which is constant, and which it undoubtedly furnishes. For the most part, it is in considerable quantity in the muscles, especially those of animal life; very little of it is seen in those of organic. In the bones, where there is none, its place is supplied by medullary substance; the cartilages, the fibrous bodies, the fibro-cartilages, are almost entirely destitute of it. The glandular system sometimes has it, as we see it in the parotids, around the pelvis of the kidnies; in other places, as in the liver, the prostate, &c. there is no trace of it. The serous and cutaneous systems are never fatty, although much fat surrounds them. It is the same of the mucous; the epidermis and the hair never have any of this fluid.

From this we perceive that the interior of the organized systems contain in general but very little fat. The different apparatus have but a small proportion between their various parts. It is thus that between the coats of the stomach, the intestines, the bladder, &c. between the periosteum and the bone, between that and the cartilage, between the muscle and the tendon, &c. this fluid is almost always wanting.

It follows from this that it is principally in the interstices, which the different apparatus leave between them, that fat accumulates in cellular reservoirs. Now by examining the different regions, in this point of view, we see, 1st. that upon the head, the cranium and face have an inverse arrangement; that it is very abundant in the second, and wanting in the first, especially in the interior; 2d. that the neck contains a considerable proportion; 3d. that in the thorax we see very little around the lungs, but much about the heart; that upon the exterior of this cavity, the superior part has a considerable quantity around the breasts; 4th. that in the abdomen, it particularly abounds in the posterior part in the neighbourhood of the kidnies, the mesentery, and omentum; 5th. that in the pelvis, there is much of it near the bladder and rectum; 6th. that upon the extremities it is found, like the cellular texture, more abundant above and in the vicinity of the great articulations, &c.

We observe in infancy, that the quantity of fat is in proportion much more considerable under the skin, than any where else, especially that in the abdomen the cellular viscera, the omentum in particular contains but very little at this age. I have established this fact in a great many instances. There are only some flakes of fat around the kidney, frequently these are scarcely visible. All the rest of the abdominal cavity is destitute of it. The pectoral cavity contains scarcely any more, and always much less in proportion than in after life. I have observed also that the intermuscular texture is almost every where deprived of it. We may say, then, that all this fluid is concentrated under the skin, at least while the fœtus is in good health. Does this superabundance of sub-cutaneous fat perform any important office? has it any connexion with the great size of the liver at that period? I know not: it is a phenomenon that should fix the attention of physiologists, especially when it is compared with the absence of fat in almost all the parts where it is afterwards accumulated.

Towards adult age, the abdominal fat is in much greater proportion than the sub-cutaneous. The exterior swelling is as rare towards the fortieth year, as it is common about the fourth and fifth, a period at which all the muscular forms are concealed by the superabundance of fat, and the body is remarkably rounded. Is there any connexion between the large quantity of abdominal fat at the adult period, and the frequency of diseases of which this region is then the seat?

However, the proportions of fat for the different ages are not always the same; there are some exceptions.

In old age almost all the fat is dissolved and disappears; the body is wrinkled, hardened, and becomes thin.

_Unnatural proportions of fat._

Oftentimes the fat accumulates in very great quantity in the cellular texture. I will not cite examples of those enormous collections, of which different authors have given a number of cases; this would be superfluous. I shall only observe, that this state of great corpulency, far from being a sign of health, indicates almost always a weakness of the absorbents which are destined to take off the fat, and has, in this point of view, much greater analogy to serous infiltrations than we commonly think. Different facts establish this assertion. 1st. Every kind of unnatural corpulency is accompanied with a debility of the muscular power, with a state of lassitude and languor of the individual who is the subject of it. 2d. In a man in whom strength and activity predominate, we do not see this fatty enlargement that hides the prominences of the muscles; these are distinctly marked. It is necessary to distinguish carefully the size of the body which arises from cellular fat, from that which is the consequence of the proper development and nutrition of the organs. 3d. Oftentimes the causes which evidently weaken the powers of life, produce a considerable quantity of fat; such as inactivity, rest, great and long continued hemorrhage, convalescence from certain acute diseases, in which the powers still languish, though fat abounds. 4th. A fatty state of the muscles is a state of evident weakness in them. 5th. I have been sometimes convinced, in examining atrophous limbs, that the small size which they retain is owing in part to the fat, which is in proportion almost equal to that of sound limbs, whilst all the other parts, the muscles in particular, are contracted and hardened. 6th. Castration, which takes from the vital powers a part of their activity, from nutrition a part of its energy, is very often marked by excessive corpulency. 7th. On the other hand, as a certain degree of development of the vital powers is necessary for generation, individuals who are too fat, in whom this degree is wanting, are in general not fitted for this function. In woman, this fact is remarkable, it is not less so in man. In other animals we make the same observation. As fowls are fattened for the table, they cease to lay eggs. Most domestic animals are governed by the same law. We should say that there is a constant relation between the secretion of semen and the exhalation of fat, and that these two fluids are in an inverse ratio to each other.

We may conclude from these facts, that if the moderate exhalation of fat indicates strength, its superabundance is almost always a sign of weakness, and that there is in this point of view a kind of connexion between fatty and serous infiltrations, as I have mentioned before. It should be observed, however, that leucophlegmasia almost always arises from an organic disease of some of the viscera, particularly the heart, the lungs, the liver, the womb, and the spleen; hence it is usually incurable, and death is the consequence of the organic disease. On the other hand, an organic disease rarely accompanies corpulency, which does not prevent a long life. If leucophlegmasia arose only from cellular weakness, I am persuaded that it would not disturb the regularity of the functions.

Great fatty collections are oftentimes an effect almost instantaneous of certain circumstances, for example, of atmospheric influence. It is thus that in twenty-four hours, a fog fattens thrushes, ortolans, red-throats, &c. so that they are unable to escape the sportsman. This phenomenon, which is very frequent in autumn, is never so striking in the human species.

The diminution of the fat is as frequent as its increase, and it may be said that there are more cases of extreme emaciation than of remarkable corpulency. The causes which diminish this fluid are these: 1st. long abstinence; the necessary fasting and sleep of dormant animals, furnish us with an example of this; so that in this point of view, fat is the nourishment which is reserved for the time when the ordinary kind is taken away; 2d. every organic disease, continued for a long time, as phthisis, cancer of the pylorus and womb, disorders of the liver, of the heart, &c.; those who are in the habit of examining bodies can judge by the external appearance, without knowing the previous disease, whether the organization of an essential part is changed. In general, in organic affections, there is not only emaciation, but also an alteration in the nutrition of the organs; they are more slender than usual. On the other hand, after an acute fever that has lasted only a few days, emaciation only is observed; nutrition, a function that is deranged as it is exercised, that is to say, slowly, is not yet sensibly affected. There is in this respect a great difference between two bodies equally emaciated; it is sufficient, in most cases, to dissect a limb of each, without seeing the internal viscera, to determine if death has been the gradual effect of an organic disease, or the sudden result of a bilious or putrid fever, &c. To the causes already pointed out, we must add, 3d. every considerable purulent collection, especially if it depends upon a chronic affection; 4th. leucophlegmasia, though we must not believe that fat and serum mutually exclude each other, since we often observe much sub-cutaneous fat in dropsical subjects; 5th. all melancholy affections of the mind which have an influence especially upon the internal life, and which affect the organs of it more particularly than those of external life; 6th. long-continued efforts of the mind, which in a particular manner affect the brain, consequently the first effect is upon animal life, though I have observed that an injury of the functions of this life has less effect upon corpulency than that of the functions of the other; 7th. all evacuations unnaturally increased, as those of the bile, the urine, the saliva, &c.; too frequent emissions of semen, &c. catarrhs, those especially that are seated on large surfaces, as the pulmonary, intestinal, &c.; 8th. long heat of summer, compared with the cold of winter, which is in general favourable to an increase of fat; 9th. running, hard labour, fatigue of every kind; 10th. long diseases, those especially where it is necessary to use only weak aliments, and not being able to continue even these for a long time; 11th. long-continued watchfulness; long sleep producing a contrary effect, that of increasing the fat; 12th. the immoderate use of spirituous liquors, &c. &c.; 13th. the use of acrid and spicy aliments, of those which have opposite properties to the farinaceous, &c. &c.

I do not cite a great number of the causes of emaciation; after these it will be easily perceived what are omitted. I would only remark, that almost all may be referred to two principles, viz. 1st. a general weakness of the powers, a weakness that acts upon the cellular system, as upon all the others, and produces there this phenomenon; 2d. a partial weakness of this system, a weakness arising from the affection of some other organ, whose action seems to increase at the expense of that of the cellular texture.

_Different states of the fat._

The fat is almost always solid and coagulated in dead bodies, but in the living it approaches nearer a liquid state, at least in certain parts, as around the heart, the great vessels, &c. Under the skin it has uniformly more consistence. In many experiments, where I have had occasion to open living animals with red and warm blood, I have never found it exactly flowing as it is when it is melted, though many authors have pretended that it is so, an opinion founded upon the belief that the vital heat would keep it melted. Undoubtedly a degree of heat equal to that of our bodies, acting upon fat out of the body, would make it much more fluid than it is in the living subject. Besides, we know that the temperature is nearly uniform, and that the degrees of the consistence of fat vary remarkably. There is a great difference between that of the omentum, which is among the most fluid of the economy, and that of the neighbourhood of the kidnies, the skin, which is much firmer. Many animals with red and cold blood have liquid fat.

In general, it appears that the nature and state of this fluid are not the same in all the regions; that the fat of the abdomen, thorax and brain differs from each other, though there is no precise rule concerning these differences.

In young animals the fat is white and very consistent after death. It is this consistence that gives to the external covering of the human fœtus, a remarkable firmness and condensation, whilst in the adult the skin of a dead body is flaccid and loose, yields to the least communicated motion on account of the state of the sub-cutaneous fat. This fat in the fœtus is formed into little globules more or less rounded, which give the whole a granulated appearance. Oftentimes it even forms considerable masses; for example there is almost always at this period, between the buccinator, the masseter and the integuments, a ball of fat, which is separate from the surrounding fat, and can be taken out whole. It contributes very much to the remarkable prominence the cheeks have at this period of life.

Fat becomes yellow as we advance in years, and acquires a peculiar smell and taste. In comparing that of veal with that of beef, we readily perceive the difference on our tables. In the dissecting room, this difference is not less remarkable between a subject of ten years and one of sixty.

Instead of fat, we often find around the heart of dropsical and phthisical patients, and of all those who have died of a disease, in which there has been a constant and protracted weakness, a yellowish substance, transparent and fluid, having a gelatinous appearance, and which however, approaches near the character of albumen. This substance also occupies in similar cases other parts; but it is less frequent there. It appears to be gelatinous rather than oily.

_Exhalation of fat._

Different hypotheses have been proposed concerning the manner in which fat is separated from the blood. Malphigi spoke of glands and excretory ducts, which no anatomist since his time has seen and which no one believes in at present. Haller supposed that the fat was completely formed in the arterial system, that it circulated with the blood and floated on its surface on account of its specific levity. This circulating fat then, according to him, escaped through the pores of the arteries, and oozed from all parts into the neighbouring cellular texture. This opinion supposes two things; 1st. the existence of fat ready formed in the arterial system, an existence that is proved by no positive fact, of which I never could convince myself by the examination of red blood as it comes out of the vessels, for if it did exist there would be numerous little drops floating on its surface at the moment it was drawn. In my experiments upon the colouring of the blood, I have frequently established this; I have observed it also in examining the blood of maniacs upon whom arteriotomy has been performed at the Hôtel Dieu. 2d. The opinion of Haller is founded upon a transudation truly mechanical, a transudation that easily takes place in dead bodies, but never in living. In fact, if we lay bare an artery of a living animal, separate it entirely from every thing else, and examine it ever so long, we shall discover no oozing of fat through its coats, though the blood circulates in it as usual. There is an infinity of arteries, spread in the cellular texture, through which fat never transudes, as we see in the scrotum, the eyelids, &c.; now in these places the arteries are organized as elsewhere, and they ought therefore to have the fat ready formed in the blood that they circulate; then, according to Haller, fat would be deposited there. Besides, we shall see under the article upon exhalations, that this transudation through the pores of the arteries, whatever fluid is supposed to be transuded is evidently repugnant to the laws of the animal economy. I refer then to this article, to establish the fallacy of Haller's opinion; under that article we shall see also, that the fat is separated by an exhalation analogous to that of all other exhaled fluids, that is to say, by the vessels of a particular order, which are intermediate between the extremities of the arteries and the cellular texture. Some authors have thought that they saw the vessels that carry the fat, and have designated them under the name of adipose; but it appears, that like the other exhalants, they are invisible and can only be proved by a train of reasoning, which however, satisfactorily establishes their existence. We can apply to the exhalants of fat, what will be said upon the exhalant system in general.

I will not treat of the chemical nature of fat, of the acid it contains, of the particular alterations it undergoes under different circumstances, that for example, that it experiences when animal substances that contain it, such as the skin, the muscles, &c. are for a long time macerated in water. This would lead me into details foreign to this work. Besides, I could add nothing to what modern chemists have said upon this subject.

I will terminate this article with an important remark; it is this, that in those parts which nature has deprived of fat, it would have injured their functions. The penis increased in size by it, would not have had a proper relation to the vagina. The eyelids loaded with fat could scarcely be raised. Accumulated in the sub-mucous texture, it would have contracted the cavity of the organs which the mucous surfaces line. Spread in that which surrounds the arteries, the veins and the excretories, it would have obstructed the caliber of these vessels; and here observe, that its uniform absence in the sub-arterial texture is a proof against the opinion of Haller upon its transudation. Accumulated in the cerebral cavity, it would have compressed the brain on account of the resistance of the bony parietes of the cranium, &c. which do not yield like those of the abdomen, when the gastric viscera are loaded with fat. In the thorax, the diaphragm can descend, and the lungs can without danger occupy less space when there is considerable fat exhaled in the mediastinum. This remark, applicable also to the serum, explains an important phenomenon in diseases, viz. that a very small quantity of fluid poured out upon the tunica arachnoides can disturb the functions of the brain, whilst a great effusion is unattended with danger in the abdomen or the thorax.

ARTICLE FOURTH.

ORGANIZATION OF THE CELLULAR SYSTEM.

The cellular system, like almost all the others, is composed of a peculiar texture and of common parts.

I. _Of the texture peculiar to the organization of the cellular system._

Much has been written upon the nature of this texture; Bordeu has given some vague ideas upon it, but no experiments. Fontana has made researches which lead but to few results, upon its intimate structure and upon the tortuous cylinders of which, according to him, it is an assemblage. Let us throw aside all hypotheses that examination does not support; let us follow nature in the phenomena of structure that she shows us, and not in those she wishes to conceal. In thus considering the cellular texture, we see that it is very different from a species of glue, with which some have wished to compare it. It is an assemblage of many whitish filaments, crossing very often certain kinds of delicate layers, which form cells with these filaments. To see this organization well, a piece of the cellular portion of the scrotum should be taken, which has no fat, and whose texture is consequently not concealed by this fluid; this portion being stretched into a kind of membrane, is seen very distinctly. Then there may be plainly distinguished, 1st. a transparent net-work, arranged in layers, which makes the foundation, if we may so say, and the tenuity of which is such, that it has been aptly compared by a physiologist, to the soap bubbles that are thrown into the air with a pipe. It is impossible to distinguish, by the naked eye, any fibre in the texture of these layers; every thing is there uniform. 2d. They are very evidently crossed by numerous filaments, which running in all directions, are interwoven in every way, all of which touch, when the cellular texture is pressed together, but when stretched out, there can be seen between them the layers of which I have just spoken. The more it is extended, the larger consequently the membrane becomes, the interstices between the filaments are greater, and the intermediate layers are also more apparent.