OF THE FUNCTIONS.

FIRST CLASS.—functions relative to the individual.

ORDER FIRST.—Functions of Animal Life.
Genus I. Sensations.
1st. Of the general sensations, or feeling,external.
internal.
2d. Of particular sensationsHearing.
Seeing.
Smelling.
Tasting
Feeling.
3d. Of pleasure and of pain.
Genus II. Cerebral Functions.
1st. Relative to sensationOf perception.
Of imagination.
Of memory.
2d. Relative to the understandingOf attention.
Of the ideas.
Of the judgment.
Of the reasoning faculty, &c.
3d. Relative to motionOf the will, which is determined bythe judgment.Of the opposition of these two causes.
the passions
4th. Connexion of the cerebral functions with lifeOf concussion.
Of apoplexy, &c.
Genus III. Locomotion.
1st. Of the immoveable attitudeson the feet Standing.
on the knees.
on the pelvis.
on the head, &c. &c.
—Prostration.
2d. MotionOf the superior extremities.Prepulsion.
Repulsion.
Diduction.
Pressure.
Elevation, &c.
Of the inferior extremities.Walking.
Running.
Leaping.
Of the trunk.Support, raising weights.
Of the whole body.Swimming.
Of gesture considered as an auxiliary to the voice.1st. Gestures of the face.
2d. Gestures of the head in general.
3d. Gestures of the superior extremities.
Genus IV. Voice.
1st. Of the voice of brutes Dumbness.
2d. Of speech.Of stuttering.
Of lisping, &c.
3d. Of singingtrue.
false.
4th. Of declamation.
Genus V. Nervous transmission.
1st. Transmission to the brain of sensationsgeneral.
particular.
2d. Transmission of motionto the locomotive organs.
to the vocal organs.
3d. Mode of transmission.

OF THE INTERMISSION OF THE FUNCTIONS OF ANIMAL LIFE.

Sleep.
1st. natural.partialof the senses.
of the brain ... Of sympathetic sleep.
of the muscles.
general.
2d. unnatural.
3d. Dreams and somnambulism.
ORDER SECOND.—Functions of organic life.
Genus I. Digestion.
1st. Of hunger and thirst.
2d. Of aliments.
3d. Of taking of alimentssolid.
fluid.
4th. Of mastication, of lubricating with saliva and deglutition.
5th. Alteration of the alimentary mass.in the œsophagus.Action of the liquor of the œsophagus.
in the stomach.Action of the gastric liquor.
in the small intestinesAction of the bile.
Action of the pancreatic liquor.
Action of the intestinal liquor.
6th. Separation of the substances thatare nutritive from those that are not.
7th. Absorption of the nutritive substance;course of the chyle inthe lacteals.
the mesenteric glands,
the thoracic duct.
the blood vessels.
8th. Excretion of the non-nutritive substanceOf the peristaltic motion.
Of the fecal matter.
Of the intestinal gas.
9th. Of vomiting, as it has its seat inthe pharynx and œsophagus.
the stomach.
the small intestines.
the large intestines.
—Sympathetic vomiting.
Genus II. Respiration.
1st. Of the air.
2d. Mechanical phenomenaInspiration.
Expiration.
3d. Chemical Phenomena relativeto the air.
to the blood.
4th. Connexion of respiration with life.Of asphyxia, &c.
Genus III. Circulation.
1st. generalCirculation of red blood.
Circulation of black blood.
Action of the heart.
Action of the arteries.
Action of the veins.
Connexion of the circulation with life. Of syncope, &c.
2d. abdominal.
3d. capillarygeneralphenomena of the motion of the blood.
change of red to black.
pulmonaryits relation with the general.
change of black to red blood.
Genus IV. Exhalations.
1st. in generalof their agents.
of their phenomena.
of their alterations.
—Sympathetic exhalations.
2d. in particular. Exhalationsserous.
cellularof fat.
of serum.
synovialin the grooves of the tendons.
in the articulations.
medullaryin the middle of the long bones.
in the extremities of the long bones,in the short and flat ones.
Genus V. Absorptions.
1st. in general.Of their agents.
Of their phenomena.
Of their alterations.
—Sympathetic absorptions.
2d. in particular. Absorptionsserous.
cellularof fat.
of serum.
synovialin the grooves of the tendons.
in the articulations.
medullaryin the middle of the long bones.
in the extremities of the long bones, in the short and flat ones.
Genus VI. Secretions.
1st. in generalOf their agents.
Of their phenomena.
Of their alterations.
—Sympathetic secretions.
2d. in particular. Secretionslachrymal.
salivary and pancreatic.
hepatic.
renal.
mucous.
sebaceous.
Genus VII. Nutrition.
1st. Of the double nutritive motion.
2d. Composition of organsNutritive matter, considered in the chyle.
the blood.
—Assimilation.
the organs themselves.
3d. Decomposition of organs.
4th. Causes that modify nutrition.
5th. Of nutrition considered ininfancyOf increase in height.
youthOf increase in thickness.
adult age.
old ageDecrease.
6th. Of natural death.
Genus VIII. Calorification.
1st. Phenomena of animal heat.
2d. Entrance of caloric byrespiration.
digestion.
absorption.
3d. Its latent state in the blood.
4th. Its disengagement in the capillary system.
5th. Its exit from the body.
6th. Of the sympathies of heat, and of sympathetic heat.

SECOND CLASS.—FUNCTIONS RELATIVE TO THE SPECIES.

A COMPARISON OF THE TWO SEXES. HERMAPHRODISM.

ORDER FIRST.—Functions peculiar to the male. Phenomena of puberty in man.

Genus I. Production of the semen.
1st. Secretion in the testicle.
2d. Residence in the vesiculæ.
3d. Excretion ....Of erection and its phenomena.
4th. Of the semen.
5th. Of eunuchs.

ORDER SECOND.—Functions peculiar to the female. Phenomena of puberty in woman.

Genus I. Menstruation.
1st. Of its seat.
2d. Of its periodical return.
3d. Of its alterations.
4th. Of its cessation.
Genus II. Production of milk.
1st. Secretion in the breastDifference of this secretion from others.
Relation between the breast and womb.
2d. Excretionspontaneous.
by suckling.
3d. Of the milk.
Genus III. Of the fluids of women proper for generation.
What these fluids are.
What is their influence.

ORDER THIRD.—Functions relative to the union of the sexes, and the product of this union.

Genus I. Generation.
1st. Sexual intercourse.
2d. ConceptionIts phenomenain the womb.
in the tubes and ovaries.
Hypotheses.
Genus II. Gestation, relative
1st. to the motherGeneral state of her functions.
State of the womb.
2d. to the fœtusOf its animal life; it is almost nothing.
Of its organic lifeFunctions that it wants.
Activity of assimilation.
Of monsters.
Genus III. Parturition and subsequent phenomena
1st. Causes and mechanism of parturition.
2d. Of the lochia.
3d. Phenomena of the new born infantDevelopment of its animal life.
Functions added to its organic.

This is a sketch of the general plan that I have adopted in my lectures. Those who have attended them, will find here some changes in one part, and additions in another. But they can easily arrange under it all the facts that are contained in this work, if they wish to refer them to a physiological classification, instead of distributing them according to the anatomical order in which I present them here.

Though a line of demarcation separates each order of functions, it is not necessary, however, to take, in too exact a sense, the divisions pointed out above. Each order is connected with the others, more or less intimately. For example, in the first class, when one order ceases, another is soon annihilated. It is thus that I have shewn elsewhere that the heart, which is the principal agent of organic life, being interrupted, the brain, which is the central organ of animal life, is immediately stopt for the want of excitement, and the functions over which it presides are destroyed. It is thus also, as I have shown, that the brain, having under its immediate superintendence, respiration, by the means of the diaphragm and intercostals, which receive the cerebral nerves, has the circulation directly under its control, and thus the whole of organic life, which ceases when its action is interrupted. It is on this account that I have considered respiration as the link that connects animal with organic life, and have proved that a fœtus without a brain, or without something to supply its place, cannot live out of the womb of its mother. Every thing is connected, every thing is united in the animal economy. We live without and within in a distinct manner, but one life cannot be preserved as a whole, independent of the other. Thus, though the functions should be studied abstractedly, we should always have in view their connexion, when we consider the whole of them as simultaneously in operation.

It will be seen that in the Descriptive Anatomy, I have adopted a classification analogous to that of physiology. The one differs, however, a little from the other, because the same organs often serve for many functions, and especially because certain functions, such as exhalation, nutrition, calorification, have not, to speak correctly, any distinct and determinate organs.

GENERAL ANATOMY.

SYSTEMS
COMMON TO ALL THE APPARATUS.

GENERAL OBSERVATIONS.

The organized systems of the living economy may be divided into two great classes. One, generally distributed and every where present, concurs not only in the formation of all the apparatus, but even in that of the other systems, and offers to every organized part a common and uniform base; this includes the cellular, arterial, venous, exhalant, absorbent, and nervous systems. The other, on the contrary, placed in certain determinate apparatus, foreign to the rest of the economy, has a less general and oftentimes an almost insulated existence; this embraces the osseous, cartilaginous, fibrous, muscular, mucous, serous systems, &c. &c.

The first part of this work will be devoted to the examination of the general systems, of the generative systems, if I may so express myself, systems which are not however of such importance that all the organized parts are necessarily provided with these six. In fine, in some there are neither arteries nor veins; in others nerves; in some but little cellular texture; but they concur to form the greatest number, and some are always found where others are wanting. Thus in the tendons, in the cartilages, &c. which are deprived of blood, there are exhalants, absorbents, &c.

In general, it appears that the exhalant and absorbent systems are the most universally diffused. Nutrition supposes this; in fact this function is the result of a double movement; one of composition, which brings to the organs, the other of decomposition, that carries from them the nutritive matter; now the exhalants are the agents of the first movement, and the absorbents of the second. As every organ is nourished, and as the mechanism of nutrition is uniform, it follows that these two systems belong to all the organs. After them the cellular system is the most generally found. Where there are no blood vessels, it is sometimes met with, and it always exists where these vessels are. Next to this, the arteries and veins are spread to the greatest number of parts. Oftentimes no nerve is discoverable, where they penetrate, as in the aponeuroses, the fibrous membranes, &c. &c. The nervous is of all the generative systems, that which is found by dissection in the smallest number of parts. The serous membranes, the whole fibrous system, the cartilaginous, the fibro-cartilaginous, the osseous, &c. appear to be deprived of it.

Particularly destined to form a part of the structure of other organs, the generative systems perform the same office for one another; thus the cellular texture enters into the composition of the nerves, and the arteries and veins; and the arteries and veins are ramified in the cellular texture, &c. It is a general intermixture of one with the other.

It may be imagined, from what has now been said, that the generative systems, considered under the relation of organs, forming a common and uniform base for all, ought to be sooner developed than others; and this, observation proves. While there is hardly an outline of the others in the first months of the fœtus, these predominate in a remarkable manner. The nerves, and their centre, which is the brain, the arteries, the veins and their central organ, which is the heart, the cellular texture, the exhalants and the absorbents, exhibit this phenomenon in a striking degree. Mere inspection suffices to prove this in the nervous, arterial, venous and cellular systems; in the other two it is proved by the wonderful activity of absorption and exhalation, at this period of life.

From what has just been said of the general systems of the economy, it is easy to perceive that they perform the most important part of nutrition. They form the nutritive parenchyma of each organ; now I call the nutritive parenchyma, the cellular, vascular and nervous outline of that organ. It is in this outline that the nutritive matter is deposited. This matter being different for each organ, establishes a difference between them. For the bones, it is phosphate of lime and gelatine; it is gelatine alone for the cartilages, tendons, &c.; fibrin for the muscles, albumen for certain other organs; so that if the nutritive parenchyma of a bone was filled with fibrin, it would be a muscle in the form of a bone, and vice versa, a muscle would become a bone with a muscular form, if its parenchyma was filled up with earthy and gelatinous substances. We should know the nature of all the living parts, if their nutritive substances were known to us; but the most of them are unknown, it is chemistry that must enlighten us upon this subject. All the organs resemble each other in their parenchyma, or at least have a great analogy. If it were possible to remove, from all the nutritive matter and leave this parenchyma untouched, we should see only among them, varieties of form, of size, of deposition of cellular layers, of vascular or nervous branches, but not of nature and composition.

In the first period after conception, the mucous mass that represents the fœtus, appears to be only a compound of the general systems. Each organ has as yet only its nutritive parenchyma, the parenchyma upon which nature has imprinted the form of the organ, that is to be developed there. In proportion as this outline is increased, the nutritive substances penetrate it, and then each organ, which until that time had been like the rest in its nature, and forming with them a homogeneous mass, begins to be distinct, and have a separate existence; each one draws from the blood the substance that is proper for it. This addition gives the attributes of thickness, of density, and of nature; but the increase of parenchyma, the augmentation of its dimensions are always antecedent to this. Whilst all inorganic bodies increase by the addition of particles, there is here at first an expansive force, from which length and breadth arise, afterwards substances are exhaled into the parenchyma, which lengthen and widen it.

By what mechanism is it, that each organ draws the materials of its nutrition from the blood, the common source? This depends entirely upon the organic sensibility peculiar to each, which places it in relation to this or that substance and not to another, and which makes it appropriate it to itself, is penetrated by it, and suffers it to enter its vessels on all sides while it draws back and contracts, to prevent what is foreign to it, from being introduced into its texture.

After this substance has continued for some time to form the organ, it then becomes foreign to it and heterogeneous; by remaining longer it would be injurious; it is absorbed and thrown out by the different emunctories; a new substance of the same kind, which is brought by exhalation, takes its place. Each organ is then constantly in a state of composition and decomposition; but this composition and decomposition vary in their proportion. The predominance of the first over the second, constitutes growth. Their equilibrium establishes the stationary state of the body, which is the case with the adult. When the activity of the second is greater than that of the first, then decrease and decrepitude follow.

Such is, in short, the manner in which the general theory of nutrition should be considered, a theory which I shall explain at length in my physiology, and upon which I will now offer a few words, to show that it is not a system formed by accident, but that it rests upon the laws of the economy, and upon its organic phenomena. Now I think that this assertion will be demonstrated, if I prove, 1st. the uniformity of the parenchyma of nutrition; 2d. the variety of the nutritive substances; 3d. the faculty which the parenchyma of nutrition has of appropriating to itself, according to the quantity of its organic sensibility, this or that nutritive substance, to the exclusion of others, of afterwards throwing out this substance, and of taking new. These are in fact the fundamental principles of this theory.

I say in the first place, that the parenchyma of nutrition is the same for all the organs, and that it is an assemblage of red vessels, of exhalants, of absorbents, of cellular texture, and of nerves; these are the proofs. 1st. These different organs are met with in all the others, as I have observed before, anatomy shows them every where, between each fibre, each layer, each point, if I may so say; they are truly the common organs. 2d. When we take away from the organs their different nutritive substances, for example, from the bones the phosphate of lime by acid, and the gelatine by boiling, there is a residue which is evidently cellular and vascular. 3d. There is no doubt but that the mechanism of the union of divided parts is the same as that of their natural nutrition. Now in the healing of wounds, the parenchyma of nutrition is first developed, and is every where the same; every where fleshy points appear, which are cellular and vascular, which have the same appearance and same character, whether they arise from a bone or a cartilage, a muscle, the skin, a ligament, &c. All wounds, in healing, like the organs, resemble each other in their parenchyma; they differ also like the organs, in the nutritive substance that is afterwards deposited in its texture, substances which vary according to the part where the wound happens to be; thus the deposit of the phosphate of lime gives to the callus a different character from that of muscular wounds, which are united by the exhalation of fibrin in the fleshy points that first arise upon the divided surfaces, &c. 4th. The mucous substance which forms the body of the embryo, appears to be nothing but cellular or mucous texture, as Bordeu calls it, which is abundantly supplied with vessels and nerves. In fact, when the organs are developed in this mucous substance, it may be seen in their interstices for a certain length of time, and exhibits there the same appearance as the body of the embryo in the first periods; gradually this substance becomes condensed, is filled with cells, and assumes the form of cellular texture; whence it may be presumed, that in this mucous state of the embryo, there is only the nutritive parenchyma of the organs; and as the parenchyma is the same in all, it is evident that the mass of the embryo must be homogeneous. Nutrition commences, and then each organ appropriates to itself the substance which is proper for it; after this it ceases to be homogeneous. From these considerations, it becomes easy to admit the uniformity of the parenchyma of nutrition, and its cellular, vascular and, in certain cases, nervous texture.

I am aware, that by admitting this common parenchyma of nutrition, it becomes necessary that it should be nourished itself, and consequently that we must go farther back; but in physiology, the art of finding the truth consists, in searching for it in secondary causes; here facts and experiments enlighten our way, beyond that, imagination only is our guide.

After having demonstrated that the organs resemble each other in a common parenchyma of nutrition, it is unnecessary to prove that they differ by the substances that are deposited there. Animal chemistry has within a few years past so much elucidated this point, that it is not worth while to waste time in refuting what has been written upon the identity of the nutritive juice.

In fine, it is easy to conceive, how each parenchyma of nutrition appropriates to itself according to the quantity of organic sensibility it enjoys, the nutritive substances that are proper for it, and which are brought to it by the circulation. It is not a phenomenon peculiar to nutrition; it is observable in all the acts of the organic economy. Thus the secretions take place only in consequence of the determined quantity of this sensibility, which, placing each gland in relation with the fluid that it should separate, makes it receive this fluid, and reject the others; thus the red part of the blood does not ordinarily pass into the exhalants, because the serous part is alone in relation with their organic sensibility; thus the substances that pass the intestines, do not stop in the biliary or pancreatic ducts, although their diameter is sufficient to admit them; thus cantharides are exclusively in relation with the sensibility of the kidneys, mercury with that of the salivary organs, &c. &c.

We see from this, that the mechanism by which the parenchymas of nutrition appropriate to themselves nutritive substances, is not an insulated phenomenon, but a consequence of a general law of organic sensibility. But why has this property as many degrees as there are organs in the economy? Why do these degrees establish relations so different between the organs and the substances that are foreign to them? Let us stop here; let us be contented with proving this fact by a great number of examples, without trying to discover the cause. We could offer nothing but conjectures upon this subject.

These few notions upon the nutritive phenomena, though indirectly connected with the subject of this volume, are not misplaced here; because in these phenomena, the generative systems upon which we are going to treat, perform the greatest part, and because we shall frequently have occasion to refer to them in the examination of the development of the organs, the development that authors have only vaguely examined, upon which the most exact and the most judicious of all physiologists, Haller, has only slightly glanced, but which however ought to receive the particular attention of physicians, of those especially who wish to consider diseases under the essential relation of the influence that age has upon them.

CELLULAR SYSTEM.

This system, which many know still, under the name of the cribriform body, the mucous texture, &c. is an assemblage of filaments, and of white soft layers, intermixed and interwoven in different ways, leaving between them spaces communicating together, more or less irregular, and which serve as a reservoir for the fat and serum. Placed around the organs, the different parts of this system act at the same time as a bond to connect, and as an intermediate body to separate them. Carried into the interior of these same organs, they essentially contribute to their structure.

The great extent of this system, which, though every where spread, is every where continuous, the number of organs it surrounds, and the multiplied relations it presents, do not allow me to describe it, as has been done, in one point of view; in order to give a complete view, it is necessary to separate the different points in which it may be examined.

I shall then at first consider abstractedly the general system, as represented by the continuity of all its parts, in order to consider it in relation to the organs that it surrounds, or to whose composition it concurs. I shall examine it afterwards independently of these organs, as it is spread everywhere in the spaces between them. In fine, its organization, its properties, its relations with other systems, and its development will be the object of my researches.

ARTICLE FIRST.
OF THE CELLULAR SYSTEM CONSIDERED IN RELATION TO THE OTHER ORGANS.

The cellular system, considered in an insulated manner, and in relation to each organ of the animal economy, can be described in two secondary relations. 1st. It forms for each organ a covering, a boundary which is exterior to it. 2d. It enters essentially into the structure of each, and forms one of the essential bases of this structure.

1st. Of the cellular system upon the exterior of each organ.

The different conformation of the different organs, establishes two very distinct modifications in the relations of the cellular texture, that is exterior to them. In one case in fact, it is contiguous only to one of their surfaces, in the other it envelopes them entirely. The first arrangement takes place, when these organs have one side free, and the other attached, as for example, the skin. The second, which is the most general, is observed, when an organ is attached every where to those in the vicinity of it. Let us describe separately each of these two arrangements.

Of the cellular system which adheres only to one side of the organs.

There are three membranous organs which are free on one side, and clothed on the other by the cellular texture; these are the skin, and the serous and mucous membranes. We can also consider here, that which covers the exterior of the arteries, the veins, the absorbents and the excretories, which are destitute of it in their interior. As this texture enters also into the structure of these vessels, most authors have examined it, in treating of them. It appears to me more convenient to present under one point of view all the parts of the cellular system.

Sub-cutaneous cellular texture.

Besides the chorion, into which, as we shall see, a great quantity of cellular texture enters, and which anatomists consider as formed by a particular condensation of this texture, the skin, everywhere that we examine it, presents a subjacent cellular layer, the quantity and density of which vary in the different parts of the body.

Upon the greatest part of the median line, this texture appears more compact, and more adherent to the skin than in many other places. We may be convinced of this, by dissecting upon the middle of the nose, of the lips, of the sternum, upon the linea alba of the abdomen, upon the range of the vertebral and sacral spinous processes, upon the posterior cervical ligament, &c. From this adhesion arises a sort of division of the two great halves of the sub-cutaneous cellular texture; a division that I have sometimes made very evident in my experiments upon emphysema. The air being driven with moderate force under the integuments of one side of the body, diffuses itself gradually, and is stopped in many instances at the median line, so that one side is puffed up and the other exhibits the ordinary state of the cells. It is oftentimes necessary to increase the force very much, in order to overcome the resistance and render the emphysema general. However, we cannot always produce this phenomenon, and sometimes the air spreads immediately every where; this takes place especially if it is forced in about the neck, for the sub-cutaneous texture is as loose there in front, upon the median line, as it is upon the sides.

It is only from the circumstance, that the sub-cutaneous texture immediately under the median line, is somewhat more compact than elsewhere, that we can say with Bordeu, that this texture divides the body perpendicularly into two equal parts. No where, but under the skin, do we see any trace of this separation. Besides, I have demonstrated in one of my works, that the division of the body into two symmetrical parts, is a general attribute of the organs of animal life, an attribute which distinguishes them from those of the internal life, which seem to be characterized by their irregularity; it is under this relation, and not under that of Bordeu, which is contrary to anatomical facts, that the median line should be described.

In the other parts of the body, the sub-cutaneous cellular texture varies considerably. 1st. The density of this texture is remarkable in the hairy scalp, which is with difficulty separated on that account from the aponeuroses and subjacent muscles. Those who have often examined patients who have died of apoplexy, know that sometimes their heads and necks are emphysematous; I have already seen four. Now whilst considerable air is found in the face, little or none is met with under the hairy scalp. 2d. In the face, the sub-cutaneous texture is remarkably loose, it is very abundant there. 3d. Upon the trunk this laxity is also very evident; it accommodates itself to the motions which the great and broad muscles perform there. 4th. Upon the extremities, the sub-cutaneous cellular texture, situated between the aponeuroses and the skin, offers almost every where an equal degree of relaxation. It is only upon the palm of the hand and the sole of the foot that, its texture becoming more compact, the adhesion of the aponeuroses to the skin is more evident, an arrangement that is favourable to the use of these two parts, which are designed to adapt themselves to the forms of external bodies, to grasp and hold them. It is to this compact texture, that must be referred the difficulty that exists of making these parts subject to dropsical effusions. Long after every other part of the sub-cutaneous texture is infiltrated, this preserves its ordinary state. I have seen two patients affected with elephantiasis, where every part of the skin and subjacent texture of the lower extremities was enormously swelled, except the sole of the foot. The contrast of this part, remaining in its natural state, with the top of the foot, which was raised to an enormous swelling, gave that peculiar appearance that all authors have noticed. At the place of the annular ligaments, the sub-cutaneous cellular texture is very compact, and the adhesion of the skin, is also very evident; hence those contractions that are seen in the limbs of infants at the place of the ligaments, the fat penetrating but very little into the cells, that are very closely drawn together.

The sub-cutaneous cellular texture has several different uses. It furnishes the skin with the great mobility it enjoys, a mobility that is particularly observable in the great motions of the trunk and extremities, in the collisions it experiences with external bodies, in the different tumours that get to a great size, as in sarcocele, which is often covered at the expense of a part of the integuments of the penis, the abdomen and the thigh, which are stretched and have a real locomotion.

It is to this texture also, that the organs subjacent to the skin owe in part the facility with which they move in the great contractions of which they are susceptible. The fat contained in great quantity in its cells, contributes to protect the subjacent parts from the impression of the external air. We know, that in general this fluid is more abundant there in winter than in summer, that it is found in a very considerable proportion under the skin of animals that inhabit cold countries, that in consequence of the emaciation that follows great diseases, the impression of the external air is often very sensible, &c.

The serum appears to be in the sub-cutaneous texture, considerably more than in other parts; it has a greater tendency to accumulate there, no doubt on account of its laxity. If we compare the quantity of fluid which enters this texture in a dropsical limb, with that which occupies the intervals between the muscles and the interstices of the fibres of the different subjacent organs, we shall see that it exceeds it considerably, and that the size of the limb is in proportion much more increased by the dilatation of the portion of sub-cutaneous cellular texture, than by that of the portions situated deeper. To be convinced of this, place at the side of a healthy, lower limb, stripped of its integuments and subjacent texture, a dropsical limb prepared in the same manner, and consequently having like the other, only its aponeurotic covering, you will see that the difference is not very great.

Sub-mucous cellular texture.

The mucous membranes have the same relations with the cellular texture, that the skin has, of which they are a continuation, and with which, as we shall see, they have a great analogy in their structure. There is then a sub-mucous, as well as a sub-cutaneous texture. But there is between them, this essential difference, that the texture of the first is infinitely more compact and condensed than that of the other, and consequently that the adhesion of the mucous system to the neighbouring parts is much greater, than that of the cutaneous system. It is to this difference that may be referred, 1st. the difficulty of dissecting the mucous membranes and of separating them from the subjacent parts. 2d. The impossibility that I have always found in many successive experiments, of producing an artificial emphysema in the sub-mucous texture, whilst I have done it almost every where else, by blowing in air. 3d. The uniform absence of this fluid in this texture, even when the natural emphysemas are the most generally spread. 4th. The equally uniform absence of serum in the sub-mucous cells, in the most general leucophlegmasia; a phenomenon essential to the functions of the hollow organs, which would soon be obliterated, if the sub-mucous texture swelled as much in dropsy as the sub-cutaneous.

Is it to the difference of texture of these two portions of the general cellular system, that must be referred the much greater frequency of phlegmonous inflammation in the second than in the first, or is it that this is less exposed to the exciting causes derived from external bodies? Both circumstances may have an effect. I believe much more readily in the first, as the throat, in which is seated, especially around the amygdalæ, the most lax of all the parts of the sub-mucous texture, is the most frequent seat of phlegmonous inflammation.

Besides, it is the firm and compact structure of the sub-mucous texture, which makes it fit to serve as a point of insertion and termination to that number of fleshy fibres that compose the muscular membranes of the stomach, the intestines, the bladder, &c. and thus to fulfil the uses that the tendons have in relation to the muscles of animal life.

Sub-serous cellular texture.

There is under almost all the parts of the serous system, as under the two preceding ones, a cellular layer, which is in general very abundant and very loose, as we may be convinced by examining it around the peritoneum, the pleura, the tunica vaginalis, the pericardium, &c. This quantity of cellular texture is particularly destined to accommodate the different changes these membranes experience, in dilatation, in contraction, and in a species of locomotion, of which they are susceptible under many circumstances. We shall see the peritoneum, for example, belong at one time to the omentum, at another to the stomach, according as this last is in a state of fulness or vacuity; now for these removals, it was necessary that there should be a great degree of laxity in the surrounding texture. It is to this, that we must attribute the ease with which the sub-serous texture is penetrated with water in dropsies, and with air in emphysema. Next to the sub-cutaneous texture, no part is more disposed to these infiltrations.

There are, however, some places, where the serous membranes adhere in a very intimate manner to the neighbouring parts. The pericardium in its two layers, the synovial glands with the cartilages and fibrous capsules, the tunica arachnoides with the dura mater, offer examples of this arrangement, which constitutes, when it is with a fibrous membrane that it makes the adhesion, the sero-fibrous membranes.

Cellular texture exterior to the arteries.

There is around each artery an extremely compact, condensed, and resisting layer, which at first sight appears to be a peculiar membrane, but which evidently belongs to the cellular system. It has the greatest analogy with that which is under the mucous membranes. It is never the seat of serous infiltrations. Fat never accumulates there, and it is never attacked with inflammation. It arises in an insensible manner from the neighbouring cellular texture, which is gradually condensed, and intermixed in such a manner, that we can detach it as a whole, so that it will represent a kind of canal corresponding with that of the artery which it surrounds and supports. Are the arterial fibres inserted in this compact texture, as the muscular fibres of the stomach and intestines are, in the sub-mucous texture? I do not think they are; for if it was the case, we could not so easily remove the cellular cylinder that surrounds the arteries; the arterial fibres seem to be whole circles, and consequently not to have, like the muscular, two inserted extremities. However, some of these fibres constantly adhere to the deepest cellular layer, when we remove it; we distinguish them by their direction and yellowish colour.

Cellular texture exterior to the veins.

The veins have an external covering analogous to that of the arteries, but it is in general less thick and compact. It cannot be taken out in an entire cylinder as easily as that of the arteries. Moreover, it does not contain fat, and but little serum, and is not subject to dropsical effusions, but uniformly preserves in all affections its original state. When we raise by layers this texture which is on the outside of the coats of the veins, we easily perceive that it is dryer than in any other part; and I have often been tempted to believe, that it does not, like that of the arteries, the excretories, and mucous surfaces, exhale an albuminous fluid which lubricates the other parts of the cellular system. We shall see that its organization, which is entirely different, forms an exception in this system.

In examining the cellular cylinder of the veins and arteries, especially that of the first, it is essential not to confound it with their filaments, and the numerous nervous branches which come from the ganglions, and form a very thick net-work around them. The cellular texture is whiter, the nerves more greyish; this becomes very apparent after a few days maceration.

I do not speak of the texture external to the absorbents; without doubt they have one like the veins, but so delicate are these vessels, that we can say nothing of them founded upon experiment and dissection.

Cellular texture exterior to the excretory ducts.

All the excretories, the salivary, urinary, spermatic, hepatic, pancreatic, &c. are evidently surrounded with a layer analogous to the preceding, entirely distinct from the neighbouring texture, and which appears to be inserted in it without partaking of its nature; it is a distinct body, as to its thickness, its form, and its texture. The filaments that compose it, not being separated in their interstices by any fluid, remain in contact with each other; so that the whole really makes a membrane in the form of a canal, which can be easily raised up like that which surrounds the arteries; it is, however, thicker than that of the veins.

Of the cellular system considered in relation to the organs that it surrounds on all sides.

Except the organs of which we have just spoken, all parts of the body are surrounded on every side with a cellular layer more or less abundant, which forms for them, according to the happy expression of Bordeu, a kind of peculiar atmosphere, an atmosphere in the midst of which they are immersed, and which serves to insulate them from the other organs, to interrupt to a certain degree the communications which would unite them in an intimate manner, which would identify, if we may so say, the existence of one with the other, if they were in immediate apposition.

The serous vapour, in which the cellular atmosphere of each organ is constantly immersed, and the fat which floats there in greater or less abundance, powerfully assist in this insulation of vitality; both form for the different organs a line of separation, which, being fluid, enjoys in a much less degree than them the vital forces, which also in this point of view, is not at their level, if I may so express myself, and which is consequently very proper, to interrupt in a certain degree the vital communications that would otherwise exist. The essential difference that there is between the peculiar life of the cellular texture and that of the other organs, renders it also very susceptible of performing alone like a solid, an analogous use independent of the fluids it contains.

It is to this insulation of the vitality of the organs by their surrounding cellular texture, that we can refer in part that of the diseases, which is only an alteration of this vitality. Every day we see an affected part contiguous to a sound one, without communicating to it its disease. A healthy pleura covering the lungs filled with tubercles, or ulcers, in phthisis; an inflamed peritoneum corresponding with the intestines, the stomach, the liver, the spleen, which remain in their natural state; the mucous membranes affected with catarrhs approaching without danger the numerous parts they cover; the sub-cutaneous organs remaining free from the innumerable eruptions of which the skin is the seat; the tunica arachnoides in a state of suppuration enveloping a healthy brain, and a thousand other similar facts; these are the phenomena that the examination of bodies constantly presents. Shall I speak of the different tumours that are formed in the midst of organs, without their perceiving it, of the numerous excrescences that grow by their side without affecting them? Dissect a muscle under a suppurating cutaneous wound, or even a most obstinate ulcer; you will not often find it different from the rest, the skin only has been affected. No doubt the difference of vitality of two neighbouring organs is an essential cause of the insulation of their diseases; but the cellular atmosphere that protects them is also an important one. When an organ sends elongations into another, it communicates to it much more easily its diseases, than if a thick cellular layer separated them; for example, we know that the affections of the periosteum and the bone are soon identified.

Let us not, however, exaggerate this idea, by describing the cellular atmosphere as an insurmountable barrier to diseases. Facts would often contradict us, by showing diseases passing from an organ to the texture that surrounds it, and from this texture to the neighbouring organs; so that we see it at one time an obstacle, and at another the means of their propagation. The atmosphere that is formed is in different cases susceptible of being charged with all the emanations that arise from the organ, or to speak in language more strictly medical and physiological, the vital forces of an organ being altered, those of the surrounding texture are often altered by communication, and gradually those of the different neighbouring organs themselves. This kind of influence that the organs have upon each other, should be carefully distinguished from sympathy, in which, a part being diseased, another part becomes affected without the intermediate ones being deranged in their functions. Here there is constantly in the communication of diseases, the same order as in the position of the organs.

A great number of local affections affords us examples of this dependance, in which an organ and its texture being diseased, the neighbouring organs afterwards become so. In phlegmon, a more or less considerable swelling surrounds the red and inflamed place; rheumatism, which affects the white parts of the wrists and fingers, produces a painful swelling around them; a considerable tumefaction in the neighbourhood of the knee is almost always the result of diseases of the joint, which affect only the ligaments, &c. Many tumours have around them a kind of diseased atmosphere, an atmosphere which extends more or less remotely, which always exists in the cellular texture, and which constantly partakes of the nature of the tumour. If it is acute, as in phlegmon, it is a simple swelling which disappears almost entirely at death; as I have often seen in dead bodies an inflamed part that was very large during life, resume by the loss of the vital forces, nearly its ordinary size. Is the tumour chronic? it is an induration more or less evident that affects, oftentimes to a distance, the neighbourhood of the diseased parts, as we see in most cancers.

This atmosphere of disease is developed not only around the affected organ, but embraces also the neighbouring ones. The inflammations of the pleura spread to the lungs, that of the convex surface of the liver to the diaphragm; pericarditis, by the influence it has on the fleshy fibres of the heart, produces in this organ the irregular motions of an intermittent pulse; peritonitis, which is exclusively confined to the peritoneum, in the beginning, terminates, when it becomes chronic, by affecting the subjacent intestines; it is this which forms chronic enteritis, &c.

It should be remarked, however, that mere contiguity without cellular texture, is often sufficient to communicate disease; for example, a carious tooth affects its neighbour; the inflamed portion of a serous membrane, in contact with healthy ones, soon produces inflammation in them; thus it is, that after inflammation has continued a short time, though the pain has announced only one point to be primarily affected, the whole surface is found attacked.

I am convinced that disease is not the only thing, that the cellular atmosphere of the organs serves to propagate, but it is also the means of communicating medicinal effects. Why is a blister often useless that is applied to a remote part in rheumatism, whilst one placed upon the skin that covers the muscle or the fibrous organ that is the seat of the disease, frequently produces a sudden effect? Why has a cataplasm applied to the scrotum oftentimes an influence upon a diseased testicle, though between the cutaneous organ and this gland there is no relation of vitality? Why do several other medicines applied also to the skin, produce an action upon the subjacent parts? The cellular texture is certainly the means of communication, as in the different applications made to the mucous membranes. A gargle is advantageous in inflammations of the tonsils; an emollient enema diminishes that of the peritoneum, &c.: now these means are not applied directly to the affected organ; their effects are transmitted by the sub-mucous texture. However, the advantages of these applications have been much exaggerated, both when applied to the cutaneous and mucous surfaces, with a view of acting upon organs of different vitality, and which are subjacent to these surfaces. Practice too often proves that they may be excited, and irritated in a certain manner, without the contiguous organ being affected, because their life and that of the organ has no resemblance or correspondence, the one is indifferent to the affections of the other, though the parts are contiguous. Who does not know, how little effect emollients, discutients, &c. have, upon tumours of the breast, of the glands of the groin, axilla, &c.? and that they are as often cured without our applications as they are with? Formerly, when a tumour appeared projecting under the skin, if it was seated in the abdominal viscera, and consequently separated from the cutaneous organ, by many others of a different and even opposite vitality, they covered it with a poultice. All modern surgeons admit the inutility of applications made in this way, and now confine them to the most sub-cutaneous organs. Perhaps hereafter we shall be sufficiently acquainted with the degree of vitality of each organ, to know when the cellular texture can be the means of communication of medicinal effects, between two contiguous organs, with different structure and properties, and when it is a barrier which stops the communication of these effects. At present we go almost always groping in the dark.

Frequently a cutaneous application acts by sympathy upon very distant organs, whilst it has no effect upon neighbouring ones, with which it has no relation; for example, a bath will check a spasmodic vomiting, while it will have no sensible effect in diminishing pain which has its immediate seat in the sub-cutaneous organs.

In general, the vital forces of any organized part are particularly altered, and consequently its injuries are produced in three ways; 1st. by a direct irritation, as when the conjunctiva is inflamed, from fresh air, or that filled with irritating exhalations; 2d. by sympathy, as when one eye being affected, the other becomes so without any apparent cause; 3d. by cellular communication, as when a bone being carious, the skin that covers it becomes discoloured, livid and swelled.

Why is the cellular texture, in some cases, the means that nature uses to defend organs from the influence of that which is diseased, while in others it serves to propagate morbid affections? Let us limit ourselves upon this point to the exposition of facts; the research into the cause, would only be conjecture.

The cellular atmosphere of each organ has relation not only to the immediate phenomena of its vitality, but also to the different movements that the organ executes; as this is more abundant, these movements are more extended. This observation is made, in comparing that which is in considerable quantities around the heart, the great arterial trunks, the eye, the womb, the bladder, the great articulations, as the axilla, the groin, &c. with that which is on the outside of the tendons, the aponeuroses, the bones, &c. and of which there is in general only a very small quantity. The extension and contraction of which its cells are susceptible, make them very proper to accommodate the great movements of the organs, those especially of dilatation and contraction, which moreover are favoured by the fluids that it contains. The organs, upon the external surface of which but little cellular texture is found, and which, however, perform many movements, as the stomach, the intestines, the brain, &c. have, to supply its place, the serous membranes that cover them. These membranes and the cellular texture are in fact the two great means, and the only ones, by which nature has facilitated the movements of these organs.

There are many organized parts with obscure motions, but which are however surrounded with a quantity of cellular texture; the kidnies are a remarkable example of this. The testicle and its membranes are also surrounded with a great quantity of this texture; so is the thyroid gland; the pancreas and salivary glands find it a thick partition which separates them from the neighbouring organs. In general, almost all the immoveable parts, which are not of much importance, and which are not separated from others by serous surfaces, as are almost all the thoracic and abdominal viscera, are every where surrounded by an abundant cellular texture.

II. Of the internal cellular system of each organ.

The cellular texture, after having covered the organs, enters every where into their intimate structure; it forms one of their principal elements. In an apparatus, which is an assemblage of many systems, each of these systems is united to the others by it; thus in the stomach, the intestines, the bladder, &c. different layers which belong to it separate the serous, muscular and mucous membranes of these different hollow organs. In the lungs, between the serous surface and the pulmonary parenchyma, between this and the divisions of the bronchia, between them and their mucous surfaces, it offers a variety of elongations more or less compact.

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.

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 h5elvis.

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.

What is the nature of these filaments? I presume that some are absorbents, others exhalants, and that many are formed in the places where the layers unite together for the formation of the cells. As the thickness arising from this union is greater, they are distinguished by more evident lines upon the cellular texture stretched into a membrane. What induces me to believe this, is, that when, instead of examining the cellular texture upon a portion taken from the scrotum, and stretched as I have described, it is observed in an artificial emphysema, as in that of the slaughter-houses for example, then there is seen upon the covering of each cell, only the non-filamentous layers of which I have spoken, without any of those filaments that were seen crossing it in the other method.

These layers have not the same thickness in all cases; quite dense when the cellular texture is contracted, they become, when it is distended with air or any other means, so fine and attenuated, that the mind cannot conceive that there is any thing organized in them. Their organization is real, however, though some have doubted it. What in fact is a texture that is nourished, inflames and suppurates, which is the seat of very distinct vital functions, and which evidently lives, if it is not an organic texture? All these vague ideas of concrete juices, of inorganic glue, of hardened juice, that have been applied to the cellular texture, have no solid foundation, and rest neither upon experiment or observation, and ought to be banished from a science in which imagination is nothing, and facts every thing.

The cellular texture has essential differences of organization; everywhere where fat or serum is accumulated, there are real cells which have little sacs communicating with each other, which form reservoirs, the sides of which are composed of the transparent and non-filamentous layers of which we have spoken; it is in these sacs that the serous and fatty depositions take place. On the other hand, in the sub-mucous texture, in that which forms the external membrane of arteries, veins, and excretories, there are none of these sacs, no cells, properly speaking, and no layers to form them. When we carefully raise this texture, and lift it from the surface upon which it is applied, and draw it a little so as to show its structure, we shall see very distinctly numerous filaments interwoven every way, forming a true net-work, meshes, if I may so express myself, but not sacs and cavities. The air distends this net-work when it is driven forcibly into the neighbouring texture; but as soon as an opening is made near it, it escapes, and the texture sinks down; when accumulated in the ordinary texture, the sub-cutaneous, intermuscular, &c. it remains in the cells, notwithstanding they have been in part opened, without doubt because the communicating openings are very small. This fact is evident in markets, where we see the cellular texture blown up, around the meats that are stripped of their skin.

It appears that the filaments that are interwoven in every way, and which form about the vessels and under the mucous surfaces, a cellular net-work, are really of the same nature as those spread in different directions in the membranous layers which make the cells, only they are nearer together, and are by themselves.

After what I have said, it is evident that there are two things in the common cellular texture; 1st. a number of fine, transparent layers, found everywhere where the texture is loose, capable of yielding suddenly to different distensions, and of retaining the fluids its cells contain, &c.: 2d. filaments intermixed with these layers wherever they are, and existing alone in certain places. These layers and cellular filaments have a remarkable tendency to absorb atmospheric moisture. We observe it in dissecting rooms, where a subject dry and easy to dissect in the morning, is often much infiltrated by evening, if the weather has been damp; now this infiltration takes place in the cellular system, which is a real hygrometer.

Composition of the cellular texture.

Chemists have placed this texture in the general class of white organs, among those which furnish a great quantity of gelatine. It has this in fact, and we obtain by a solution of tannin a remarkable precipitate from the water in which this texture has been boiled, without any foreign organs except the vessels that run through it, as, for example, that of the scrotum. I have made this experiment. But, however, different re-agents act very differently upon this texture, as they do upon the fibrous, cutaneous, cartilaginous textures, &c.

Exposed to the action of the air, the cellular texture dries quickly, but without taking the yellowish colour of the fibrous texture; it remains white. When it is dried in considerable layers, its cells adhere together, and these layers being stretched a little to facilitate the drying, represent a true serous membrane, so that it would be impossible to distinguish it from one dried in the same way. In this state the cellular texture is pliable; it can be bent with great ease in every direction; it has not the stiffness of dried fibrous texture; when immersed again in water, it takes but imperfectly its former appearance; its cells are separated with difficulty.

Exposed to putrefaction with other animal substances, it yields to it less readily than many of them, for example, than the glandular and muscular organs; filled with the putrefactive juices it does not become pulpy until some time after these parts. This fact is particularly remarkable in the sub-mucous texture, in that which surrounds the vessels; the filaments that compose it, resist much longer than the other parts of the cellular system, the putrefactive process.

The same may be said of maceration as of the preceding phenomena. In looking at a tendon and a portion of cellular texture, who would say that the action of water would soften the first quicker than the second? the one being soft and almost fluid, and the other compact. After remaining in water three months, of the temperature of a cellar, the cellular texture of the arteries did not appear to me to have undergone any alteration. The sub-cutaneous, the sub-serous, the intermuscular textures, &c. are changed sooner, but not so soon as that of some other organs. I have kept for six months, in a glass vessel, some nerves, which as we shall see, are not altered in water; the texture which separated the fibres of these, was as firm and distinct as at first. This resistance to the action of water is less, when the cellular texture is macerated with organs that soon yield and become pulpy, than when it is exposed alone. This resistance is the more remarkable, as this texture, being very fine, is accessible at many points to the contact of the fluid. If the texture of tendons, of cartilages, of aponeuroses, of the skin, &c. was arranged in layers as fine and as much separated, I am satisfied that three or four days of maceration would be sufficient to reduce them to a mere pulp.

As much may be said of ebullition; a few minutes would be sufficient to dissipate and melt into gelatine most of the white textures, if they were arranged in layers as fine as the cellular system; this, however, resists a long time; different layers are still seen between the fibres of the boiled muscles. The fat which remains in parcels among the fleshy fibres, after the boiling, would have been melted, if it had not been contained in cells which continue untouched; we can, moreover, be easily convinced of the existence of these layers in the parcels of fat. It is especially upon the texture exterior to the arteries, the excretories, &c. that the action of boiling water is longest in producing an effect.

The cellular texture that is boiled exhibits phenomena analogous to other organs treated in the same way. 1st. At the instant of boiling, when an albuminous froth rises upon the water that contains it, it remains soft, and about the same it was at first. 2d. When this froth is formed, it becomes hard, is crisped and contracted in size. The hardening increases until it boils, which takes place almost immediately. In this state the texture is firmer; it has become elastic; if drawn in an opposite direction, it suddenly returns, which it would not do before. 3d. Ebullition being continued, it gradually softens and loses the hardness it had acquired; then it can hardly be extended at all; it may be much elongated without breaking, in a natural state, the rupture of it is now the effect of the least effort. 4th. In fine, by the continued action of boiling water, it gradually melts. I have remarked, that it does not in any period of ebullition, assume the yellowish tinge, which is spread over the whole of the fibrous system when boiled.

From the phenomena that cellular texture offers when exposed to the action of dry and moist air, of cold and boiling water, &c. I presume that it is less easily changed by the gastric juices than many others, the muscular texture, for example; besides, the following facts prove this. 1st. The taste, almost always a certain index which nature has given us to judge of digestible aliments, is much less gratified with the cellular texture that is mixed with cooked meat, than with the meat itself. 2d. I have made this experiment upon myself; when my stomach contained a sufficient quantity of food, I excited vomiting nearly an hour after eating; when it contained but little, I could not vomit without taking a large quantity of warm water; I then threw up this and with it the aliments the stomach contained. I have frequently ascertained by these means, especially by the last, that the cellular lumps which are found with the fleshy fibres of boiled meat, are much longer in being altered than the fibres themselves; these last have become pulpy before the others are acted upon. The fat, which generally fills these cellular lumps, may have an influence also in this phenomenon. 3d. I have made the same observation upon dogs that I have opened at different periods of digestion to determine the difference of the bile in the cystic and hepatic ducts, a difference of which I have already given some account.

How can the cellular texture unite to the softness and delicacy that characterize it, a greater resistance to the different re-agents, than that of other textures much more firm?

We know that in those who are drowned, a great quantity of gas disengaged from different organs, from those especially that contain much blood, as the muscles, the glands, &c. fills the cellular texture, renders it emphysematous and makes the body float. This does not so often take place in the open air, where putrefaction is sudden and where there is a discolouration and disorganization of parts. The tendons, the aponeuroses, the cartilages, the bones, &c. have appeared to me in animals drowned for the purpose, not to assist in the production of this gas. The cellular texture itself has less part in it, I think, than the organs before pointed out. It would be easy to know the kind of gas that each organized system furnishes, by macerating these systems separately in closed vessels, so arranged that their aeriform products might be collected. If each has a peculiar mode of putrefaction and gangrene, &c. if in this state their appearance is different, it is presumable that the products that escape from them are also different.

In dead bodies that are buried, and beyond the reach of the air, the emphysematous swelling often takes place, and it is sometimes so powerful, as I have observed in a church-yard, that it will raise the lid of the coffin, though it may be covered with half a foot of earth, which raises it then above the level of the earth that covers the other coffins.

II. Parts common to the organization of the cellular system. Blood vessels.

We must not judge of the vessels of the cellular texture by injections. When they are fine and have succeeded well, a thousand different threads interlaced in every way, destroy its whitish colour and change it into a vascular net-work. The appearance of a body thus injected is deceptive; it arises from this, that the exhalants have admitted a fluid forced through the arteries, whilst their own sensibility would repulse the blood in an ordinary state. In dissecting the cellular texture upon a living animal, it is seen to be white as in the dead body, and that great trunks that do not belong to it, send off in passing through it different branches and ramifications that are evidently lost in it. In raising the skin from the subjacent organs, the sub-cutaneous texture is distended, and we may clearly distinguish in it different little branches that end there; this is remarkable in dogs. By first making the cellular texture emphysematous, the experiment succeeds better. We see, also, very well in this way, that the blood varies in the vessels; often after being exposed sometime to the air, there appears double the number of them there was when it was laid bare. There are always remarkable variations, if the place that is denuded is examined even for a short time; it is the blood retained in the exhalants, and it seems thus to increase the number of little arteries.

Exhalants.

The existence of the exhalants is rendered evident, 1st. by the preceding experiment, which is a natural manner of injecting them; 2d. by artificial injections, which shows there many more vessels than ordinary; 3d. by transudations that sometimes take place in the cells, when these injections are driven with much force, transudations that really form an artificial exhalation; 4th. by natural exhalation, which is continually going on, and which has for its materials the fat and the serum; 5th. by accidental exhalations that sometimes take place, as when the blood is diffused in and colours serous infiltrations, &c.

Few systems in the living economy are furnished with a greater number of exhalants; I do not speak of those that contribute to its nutrition and that are consequently found there as in all other organs. The superabundance of these vessels is owing to the continual exhalation that is going on there. It is this superabundance which renders, as we shall see, inflammation so much more frequent in a part where the cellular texture is in the greatest abundance; it is this that exposes it to that variety of alterations, in which its texture, loaded with the different substances it exhales, has a firm appearance, and offers at one time a fatty substance, at another a gelatinous one, sometimes a species of scirrhus, &c. &c.

Absorbents.

The absorbents correspond with the exhalants in the cellular system; the eye cannot trace them, injections would not reach them. But their existence there is proved, 1st. by the natural and constant absorption of fat and serum; 2d. by the more manifest one that produces resolution of serous infiltrations in dropsies, sanguineous in ecchymosis, purulent in the different kinds of abscesses that are removed; 3d. by the disappearance of mild fluids injected into these cells, an effect that must be owing to the agency of these vessels; 4th. by the resolution of natural and artificial emphysema, in which the air, or at least the principles that constitute it, have no other way of escaping. This is evident when the emphysema arises from a rupture of a bronchial cell, and when a very little opening is made in the animal, it is stopped after the air is driven by it into the sub-cutaneous texture; this I have convinced myself of. 5th. The drying up of external ulcers is owing to the cellular absorbents. Oftentimes in phthisis the ulcers are suddenly emptied, and we find in the subject who dies immediately, only the place that was occupied by pus or sanies; I have already known two patients to die in this way by a re-absorption almost instantaneous and exactly analogous to that of external ulcers. 6th. Where there is the most cellular texture, we meet with the greatest number of absorbents, and the most of those bodies with a glandular appearance, in which these vessels ramify. Where the cellular texture is scarcely discoverable, as in the brain, we can with difficulty see the absorbent system, &c.

We must consider, then, the cellular system as the principal origin of the absorbents, of those especially which serve to carry the lymph. These vessels and the exhalants appear to contribute particularly to the formation of its structure. Many have thought that it was exclusively formed of them; but this is not founded either upon observation or dissection. We see a transparent filamentous texture, and nothing more. Each cell is a reservoir intermediate between the exhalants that terminate and the absorbents that arise there. They are in a small way what the serous sacs are in a large one. We do not see the orifice of either set of vessels.

Nerves.

We see many nerves running through the cellular texture. But do these filaments stop there? Dissection affords no light upon the subject; it arises perhaps from this, that these filaments being white like the texture, we cannot see them at their termination as well as we can the arterial branches, which are rendered apparent by their colour, when they contain red blood.

ARTICLE FIFTH.
PROPERTIES OF THE CELLULAR SYSTEM.

I. Properties of texture.

The properties of texture are strongly characterized in the cellular system.

Extensibility.

Extensibility is proved in a variety of cases, as in œdema, in the accumulation of fat, and in different tumours, in which the cells are much spread and the membranes remarkably elongated. All the natural motions suppose this extensibility; the arm cannot be raised without the texture of the axilla acquiring an extent double, or even treble, what it has when the arm is down. The flexion and extension of the thigh, of the neck, and of almost all the parts, exhibit in different degrees analogous phenomena. If we raise any organ from those to which it is contiguous, the intermediate texture is considerably elongated.

The degrees of the extensibility of the cellular texture vary. In the sub-cutaneous, the sub-serous, the intermuscular, &c. this property has much more extended limits than in the sub-mucous layer, in that exterior to the arteries, the veins, and the excretories. It exists, however, in this, as is proved by the dilatations of the gastric viscera, aneurisms, varices, &c. But these phenomena themselves prove the greater difficulty of extension in this species of texture; for example, the ordinary texture would be incapable of resisting the impulse of the blood after the rupture of the coats of the artery. There would be a sudden, enormous, and often fatal dilatation, if the arteries were only surrounded by this. It is the thickness of that which covers them, which makes the progress of these tumours slow and gradual.

It is in fact an essential character of the extensibility of almost all the cellular system in which the layers and consequently the cells are united, to have the power always of being put suddenly in action and in an instantaneous manner. We have an example of this kind of extension in emphysemas artificially produced, which make this texture go suddenly from a state of perfect contraction to the greatest extension of which it is capable. The artificial injection of different fluids exhibits the same phenomenon. We observe it also as a consequence of fractures, and contusions of the limbs, in which we sometimes see enormous swellings appear in a manner almost as sudden. The cellular texture is evidently the seat of those swellings which take place in that texture which is sub-cutaneous, and not in that subjacent to the aponeuroses, because the extensibility of these membranes not being capable of being suddenly put into action, resists all dilatation that is not gradually made. Many other organs, as the tendons, the cartilages, the bones, &c. though possessing, like the cellular texture, extensibility of texture, differ from it like the aponeuroses, in the impossibility of being suddenly distended. In general, the softness of the primitive structure appears to have great influence upon this modification of extensibility.

The cellular texture, extended too far, becomes at first very thin, and then breaks. In a natural state, no motion of the economy is capable of being carried so far as to occasion this; for example, I have remarked in regard to cellular texture taken from the axilla, that it is necessary to extend it at least three times as far as it is in the elevation of the arm, to produce this phenomenon. Besides, what opposes also this rupture, is a kind of locomotion of which it is capable; so that if too violently drawn, it displaces that which is contiguous to it, draws it towards itself, and thus becomes less stretched. We see this phenomenon in a remarkable manner in the swellings of the testicle, in large hydrocele. Then all the surrounding texture, that of the lower part of the abdomen, the top of the thighs, and the perinæum, drawn by that which immediately covers the tumour, is thus brought also upon it.

I have observed that the inflamed cellular texture loses in part this property, and that upon the dead body it breaks with great ease. This takes place also in different indurations of which it is the seat. For example, that surrounding a cancerous womb, being swelled, loses the capacity of being extended; it is brittle, if I may be allowed to use the word; the least effort is sufficient to break it. This fact is uniform in all cancerous affections, somewhat advanced, of the womb and in those of many other organs.

Contractility.

Contractility of texture always takes place in the cellular system when extension ceases. Thus in emaciation, in the resolution of dropsy and of tumours, the cells contract and lose a great part of the capacity they had acquired; in a wound which has affected the cellular texture as well as the skin, the edges separate, and a space remains between them owing to the contraction of the cells.

As we advance in life, this contractility takes place with less ease; youth is the period of its greatest energy; thus in consequence of great emaciation that takes place in old men, the skin is flaccid and wrinkled, because the subjacent cellular texture not having contracted, the cutaneous covering remains at some distance from the external organs and cannot lie close to them. In a young man, on the contrary, who has become emaciated, the skin is exactly applied to the organs, it preserves its tension; because the cells in contracting draw it with them; these form the external prominences. It is necessary to observe these prominences; in the face, with the folds of the skin, they form what are called prominent features.

II. Vital Properties.

The animal properties are not among the attributes of the cellular texture in an ordinary state; we can with impunity cut it, draw it in different directions or distend it with gas. An animal that undergoes these experiments gives no indication of suffering. If he feels any pain, it is from the nervous filaments that pass through the texture, and which may be accidentally irritated. In disease however, the sensibility is raised to such a point, that it may become the seat of acute pain; phlegmon is a proof of this.

The organic properties are very distinct in the cellular texture; fat and serum could not be absorbed there, if they did not make an impression that brings into action organic sensibility. I would observe concerning this property considered in the cellular system, that all substances have not an equal relation to it; among the animal fluids the blood, the lymph and milk do not raise it so high, when they are effused or injected there, as to prevent absorption, which takes place of them as well as of fat and serum. On the other hand this sensibility is so altered by the contact of urine, bile, saliva or other fluids destined to be thrown out, that inflammation is often the consequence, and prevents absorption. Among the foreign fluids injected water is absorbed. Wine and almost all other irritating fluids excite suppuration, and are thrown out with the pus that arises from them. We know that in the operation for hydrocele, abscesses in the scrotum are always the consequence of an accidental passage of the injection into the cellular texture. Experiments upon living animals agree perfectly with this fact; every other irritating fluid, diluted acids, alkaline solutions, &c. produce the same phenomenon.

Insensible organic contractility is clearly proved in the cellular texture, by the exhalation and absorption that take place there.

It has to a certain extent sensible organic contractility. We know that cold alone is sufficient to contract the scrotum in a remarkable manner; that as it is irritated or not, this part has various degrees of contraction and relaxation; now it appears to contain under the skin only cellular texture; the filaments of which, it is true, have a particular appearance and seem to differ in their nature from the filaments of the other portions of this system. This contraction to be sure is not to be compared to that of the muscles, but it is certainly the first degree of it; it is of the same nature, or rather it is a medium between this and those oscillations that cannot be described, which we designate under the name of insensible organic contractility, and others call tone.

Sympathies.

The relations of the cellular with the other systems are very numerous and multiplied; but oftentimes it is not easy to perceive them clearly. In fact, as it is disseminated in all the organs and contributes to the structure of all, it is frequently difficult to distinguish what belongs to it, from that which is an attribute of the parts where it is found. These relations however, become evident under various circumstances; in acute as well as chronic diseases, it is very susceptible of the influence of the affections of the organs. I do not here mean the alterations arising from juxta-position and continuity, alterations so common as we have seen, but those produced in parts of the cellular texture that have not any known relation to the affected organ.

In acute diseases which have their seat in a particular organ, as in the lungs, the stomach, the intestines, &c. the cellular texture is often sympathetically affected; it becomes inflamed, suppurates, &c. Most critical deposits arise from this real though unknown connexion between the affected organ and the cellular texture. Oftentimes it is the natural exhalation or absorption of this texture that is deranged in acute affections; hence the swelling, and dropsies that sometimes suddenly arise. I attended a man in the ward Saint Charles who, in consequence of great terror, had a sudden contraction of the epigastric region; a tinge of the jaundice, an indication of the affection of the liver by the emotion of the mind, spread in a few hours after over his face. In the evening he had great œdema of the lower limbs, an œdema produced, without doubt, sympathetically by the influence of the liver upon the cellular texture. This influence of the principal organs upon this system becomes especially remarkable in chronic affections, in the alterations of texture they experience. We know that most of the gradual diseases of the heart, the lungs, the spleen, the stomach, the liver, the womb, &c. have among their symptoms, in the latter stages, a dropsy more or less general, which arises from the debility created in the cellular texture. Medicine owes much to Corvisart, for being among the first to perceive that almost all infiltrations are symptomatic, that almost all consequently depend upon an influence produced by the affected organ upon the cellular texture. That comes on gradually then, which took place suddenly in the patient I mentioned just now.

We see in all acute diseases, that the skin very easily perceives the sympathetic influence of diseased organs, that it is many times alternately dry or moist, oftentimes in the same day. I am convinced that the cellular texture experiences the same alterations as the skin, and that if we could see what is going on there, we should perceive that its cells are more or less moist, or more or less dry, according to the kind of influence it receives; it is to this also that must be referred the different state of bodies that have died of acute diseases, which present innumerable varieties in their cellular serum.

Most physicians consider in too general a manner a number of symptoms, which, to speak correctly, do not depend as they imagine, upon the disease, but wholly upon a sympathetic affection produced by the diseased organ upon the sound ones, which, according as they are affected, give rise to different phenomena truly foreign to the disease, that sometimes render it complicated but do not form an essential part of it; they can take place or not, and the disease remains the same.

Observe that organic sensibility and contractility are almost always in action in cellular sympathies, because these are the two vital forces essentially predominant in that system. Thus sensible organic contractility and animal contractility are particularly exercised in muscular sympathies, according as the system of organic muscles, or that of the muscles of animal life, receive sympathetic excitement.

The cellular system not only receives the influence of other organs in its sympathies, but it exercises its own upon them. In phlegmon, which is the inflammatory state of this system, if the tumour is considerable, different alterations are oftentimes discoverable in the functions of the brain, the heart, the liver, the stomach, &c. Sympathetic vomiting, which is called an overflow of bile, delirium, &c. are phenomena that are seen with large phlegmonous swellings without belonging to the disease itself. Art avails itself of the influence of the diseased cellular system upon other organs, in the introduction of setons. Oftentimes in diseases of the eyes, a seton produces an effect that cannot be obtained from a blister: why? because the relation that exists between the cellular texture and the eye, is more active than that which unites the latter to the integuments.

Characters of the vital properties.

After what has been said, we see that the vital activity is sufficiently evident in the cellular system. In this point of view, it is much superior to other organs that are white like it, and among which it has been ranked, such as the aponeuroses, the tendons, the cartilages, the ligaments, &c., organs remarkable for the obscurity of their vital forces and the dullness of their functions. Thus the phenomena of inflammation go through their different periods much quicker in this system. Their progress is very rapid, compared to that of different tumours that appear in the systems of which I have just spoken.

Suppuration takes place here with a rapidity of which we have an example in but few of the organs. Every one knows the fluid that comes from this suppuration. Its colour, its consistence, all its external qualities have become the type to which we refer the ideas that we form of pus; so that that which does not resemble it, is considered to be pus of a bad kind, or as we say sanious. This opinion is incorrect. Certainly the pus that flows from a bone, a muscle, the skin in erisypelas, the mucous membranes in catarrh, is of a good kind so long as the inflammation is regularly going through its periods; it is however totally different from cellular pus. As this is most frequently observed, especially in surgery, we have formed a general idea of laudable, as of sanious pus. Cutaneous, mucous, osseous pus, &c. have each their peculiar sanies, which differs among them according to the vital alterations of the organ, from which it is derived. So that the pus of each system differs from that of the others, in the same way as the alterations of which it is susceptible are different from their purulent alterations.

Has the cellular texture peculiar vital modifications in those organs to whose structure it contributes? From what has been said above, it seems hardly probable. All that I have been saying, applies to the system considered in the interstices of the organs, separate from all combination with their structure. It is possible however that its vital activity is diminished in the cartilages, the tendons, &c., that it is increased a little in the skin, that its life, in general tends to an equilibrium with that of the parts in which it is found; but these are conjectures that nothing positive confirms.

That which ought not to escape us here, is the manifest difference of vitality that exists between the texture of layers and filaments almost every where spread, and the texture that is wholly filamentous, which is exterior to the mucous surfaces, to the blood-vessels, and excretories, a difference from which arises the rareness of inflammation and tumours in this last. It is often a real barrier that stops the affections of the first, a barrier that protects the organ it covers. Thus I have many times observed in opening bodies, that whilst the ordinary texture, in which the arteries are embedded as in the axilla, is in a state of suppuration, and almost disorganized by the pus, that which forms the external covering of the vessels remains untouched; it has not undergone the least alteration. I have seen the same phenomenon in the texture exterior to the urethra in deposits of pus at the loins.

III. Properties of re-production.

The cellular texture is distinguished from other organs by the faculty it has of throwing out a kind of vegetation, of elongating and re-producing itself, of growing when it has been cut or divided in any manner. It is upon this faculty that depends the formation of cicatrices, tumours, cysts, &c.

Influence of the cellular texture upon the formation of cicatrices.

Cicatrices may be considered under two relations, 1st. in the external organs, in the sub-cutaneous texture and skin particularly; 2d. in the internal organs. Let us examine them at first in the external.

Every wound that follows the ordinary periods, presents between its formation and its cicatrization, the following phenomena; 1st. it inflames; 2d. fleshy granulations are formed upon its surface; 3d. it suppurates; 4th. it sinks down; 5th. it is covered with a fine pellicle, red at first and afterwards becoming whitish. Let us trace these different periods.

First period.

Inflammation commences the instant the wound is made. This is the sudden result of the irritation caused by the instrument, the contact of the air, the dressings and surrounding bodies. Shut out until then from the contact of the air, most of the parts concerned in the solution of continuity, enjoy only organic sensibility; but then these contributing to form the surface of the body, ought to enjoy animal sensibility, that which transmits to the brain the impressions that are received. Now the effect of inflammation upon organs endowed only with the first kind of sensibility, is to raise it so much, that it ascends to the same degree as the second, and can like it, transmit to the brain its impressions; so that by it the parts divided by a wound become capable of performing the functions of the integuments. This is the first advantage, without doubt, of this inflammatory period of cicatrization.

Another advantage of this period is to dispose the parts to the development of fleshy granulations. In fact, inflammation always precedes this development; now the increase of life that it produces in the organs, appears to be necessary to animate the parts that are to be reproduced; by it the cellular texture, where the granulations are formed, is endowed with more sensibility and more insensible contractility; it raises it to a temperature above that of the neighbouring organs; it becomes the centre of a small circulating system independent of that of the heart. It is in the midst of this extension of the forces, that the fleshy granulations arise and increase, for the production of which the natural forces would have been insufficient. Hence the paleness and flaccidity of these granulations, when these different functions are weakened or cease.

Second period.

The production of fleshy granulations succeeds to inflammation. It presents the following phenomena; small reddish bodies, like tubercles, arise, unequal and irregularly disposed upon the surface of the wound; they are not fleshy, as their name, given, no doubt, on account of their colour, would indicate; they are little cellular vesicles, filled with a thick substance, like lard, which we are unacquainted with, and which it is important to analyze. This substance so fills the cells, that in blowing air into the texture subjacent to a wound, whether in a living or dead body, this fluid does not enter the granulations; they are raised up entire, but no one of them is developed or distended as the cells which this substance does not fill; the granulations remain the same in the midst of the general bloating. I have often made these experiments upon animals that I have wounded for the purpose.

In proportion as the granulations are developed upon an exposed cellular surface, we see them unite together, and form, by their union, a kind of provisional membrane, which absolutely prevents the contact of air upon the subjacent organs, while the true cicatrix, that which is to be permanent, is forming. This provisional membrane of cicatrices, this kind of epidermis destined to defend the parts during the work of cicatrization, differs from common serous membranes in this, that they are smooth and every where uniform, whilst the granulations produce here an unequal and rough surface. This inequality of the granulations and their separation, appear to be opposed to what I have said concerning the first state of cicatrices; the following experiment leaves no doubt upon the subject. I made a large wound upon a dog, and let it go through its first periods; the animal was then killed. I removed a portion of flesh upon which the granulations were developed; I distended it by a prominent body, placed on the side opposite to the granulations, so as to make the granulated surface convex, that had been concave; the tubercles were effaced; the provisional pellicle, stretched out, became very evident; it might have been taken for an inflamed serous membrane.

It follows hence, that when the granulations are united together, that the air is entirely excluded, and that what is commonly said of the contact of this fluid is inaccurate and contrary to the arrangements of nature, which knows how better than we can do by our dressings, to cover over a divided part, whilst the work of cicatrization is prepared and effected.

These are the general phenomena that cutaneous cicatrices offer in the two first periods of their formation. The internal cicatrices show nearly the same thing. Now it is easy to prove that the cellular system here performs not only an important but an exclusive part, and that all these phenomena take place in its texture or its cells. The following observations prove in a satisfactory manner the cellular nature of the granulations and the provisional pellicle that arises from them. 1st. Where the cellular system is most abundant, as in the cheeks, granulations grow most easily and wounds are soonest healed. 2d. The skin, stripped too much of the cellular texture, is not covered with ease with these productions, and adheres with difficulty to the neighbouring parts; hence the precept so strongly inculcated in surgery, of saving this texture in dissecting out tumours, in the extirpation of wens, cysts, &c. 3d. Maceration always reduces to this first base the surfaces of granulating wounds, when we expose a dead body that has one to this simple experiment. 4th. The nature of fleshy granulations is the same every where, whatever be the organ that produces them, whether a muscle, a cartilage, the skin, a bone, a ligament, &c.; only they are more or less backward, according as the life of each organ is more or less active, more or less decided, and the vital forces found there marked in a greater or less degree; thus they appear at the end of four or five days upon the skin, and it is very much longer before they are visible upon the bones; but their structure, their external appearance, their nature, are always the same; then they are only the expansion, the enlargement of an organ, that is met with in all the others; now this organ common to all, this general base of every organized part, is the cellular texture.

From the red colour of fleshy granulations, it has been thought that they were a vascular expansion; but their development is unlike every production of the blood-vessels. On the one hand we have seen, that the cellular texture contains so many exhalants and absorbents, that it seems to be almost made up of them; on the other hand, we shall see that in inflammation a passage is constantly given to red blood in this kind of vessels; then, as the fleshy granulations are cellular, they consequently partake of the nature of this system; and when found in a real inflammatory state, we conceive that their redness is the same as that of an inflamed pleura, of the cellular texture that has become the seat of phlegmon, of erisypelatous skin, &c.; a redness that does not imply an elongation of blood vessels, but only the passage of red blood, in those that usually carry white. This is so true, that when the inflammation is gone, the blood ceasing to enter these vessels, the membrane takes its natural colour; so that the granulations, after the formation of the cicatrix that arises from their near approach to each other, whiten because the blood no longer enters them. Now if it had been a new production of vessels, they would continue and perform their functions. Moreover, how can we suppose a development of blood-vessels where they did not primarily exist, as in the tendons, the cartilages, &c. which have, like other organs, fleshy granulations in their solutions of continuity?

Let us conclude from these circumstances, that the arterial system is not connected with the formation of fleshy granulations; that the cellular system is alone concerned in it, because that this alone is endowed with the faculty of increasing, extending, and reproducing itself.

This is what takes place in the second period of the cicatrization of wounds; the cellular texture, by the increase of power that it acquired in the first period, is raised into vesicles irregularly disposed, which exhale a white substance, that is not well understood, and unite at their superficies and form a provisional membrane. But how is this membrane changed into that of the cicatrix? Observe nature, and you will see that it brings on suppuration and a sinking down of the parts, before the arrival of this period.

Third period.

The period of suppuration does not take place in the cicatrization of the bones, in that of broken cartilages, of torn muscles and generally in the reunion of all divided organs without external wounds. We must then show what relation there is between their cicatrices and those of the external organs; for a common principle presides over all the operations of nature, though they may have a different appearance.

When a bone is broken, the two first periods of its reunion are the same as those of the external organs; the ends inflame, and then are covered with cellular granulations. In the third period, these granulations, having first united together, become a kind of secretory or rather exhalant organ, which separates first the gelatine which encrusts it, and gives to the callus a cartilaginous nature, and then the phosphate of lime which completes the osseous arrangement. In the cicatrization of cartilages, gelatine only is exhaled; in that of the divided muscles, fibrin, &c.; in a word the cellular texture is the common base of all the cicatrices of the internal organs, then the fleshy granulations are the same for all; they resemble each other in each having the same base; that which establishes the difference between them, is the substance that is separated, and which remains in the cellular texture. This substance is generally the same as that which serves for the nutrition of the organ, and which is by this function, constantly carried there and brought away. Now as each organ of the different systems has its peculiar nutritive substance, each has its peculiar mode of reunion; we should understand the cicatrization of the different organs, as well as that of the bones, if the substances that nourish these organs were as well known as gelatine and phosphate of lime. The mode of development of the internal cicatrices is in general analogous to that of nutrition, or rather it is the same with this difference only, that the cellular texture rising into irregular granulations upon the divided surfaces, does not afford to the cicatrix a base formed upon the shape of the organ; hence the inequality of callus, &c.

This then is what in general takes place in the third period of the cicatrization of the internal organs: phenomena very analogous are seen in that of the external. The membrane which covers the fleshy granulations thus becomes a kind of exhalant organ which separates from the blood a whitish fluid that is called pus. But there is this difference, that instead of remaining in the texture of the granulations, of penetrating and encrusting it, as the phosphate of lime and gelatine penetrate the bone, it is thrown out and has nothing to do with the reunion; so that in internal cicatrization there is exhalation, then incrustation of the exhaled fluid, and in the external, there is exhalation and then excretion of this fluid.

Besides, an internal wound which affects the cellular texture and suppurates, appears to me to resemble perfectly serous surfaces, which are covered in consequence of their inflammation with a purulent exudation. The fine pellicle that covers the granulations is of the same nature as an inflamed pleura or peritoneum, that is, it is essentially cellular. The pus is in both cases almost of the same nature, and analogous to that of phlegmon, because it comes from similar organs, whilst if the skin alone is concerned, this fluid is of a very different nature, as we see in erisypelas.

The exhalation of pus upon a cicatrizing surface and serous membranes, appears to me to have a great analogy with the whitish substance of some kinds of cysts.

Fourth period.

Suppuration gradually exhausts the whitish substance that fills the granulations; then their cells, which were at first swelled, insensibly diminish in size, they close by their contractility of texture; by degrees they adhere to each other, and from their adherence arise the following phenomena. 1st. All the fleshy tubercles disappear and there is a uniform surface in their place. 2d. This surface is a very fine membrane, because the thickness of the granulations arose not from the cells, but the substance they contained, and which being taken away, leaves them empty. 3d. This membrane has infinitely less width than the pellicle that first covered the granulations, because the cells in contracting, draw the edges of the cicatrix from the circumference to the centre; these approximate, and the breadth of the wound diminishes; the same granulations that in the beginning occupied a space of half a foot diameter, as for example in the operation for cancer, are often contracted to an inch or two.

When the adhesion is complete between all the cells that first form the fleshy granulations, the membrane of the cicatrix, the result of this adhesion, exists. Thus it is that all the flesh, the development of which astonishes us, and which amply repairs the loss of substance, is but a pellicle, reddish when the exhalants are full of blood, but afterwards white by the return of this blood into its vessels.

From this mode of origin of external cicatrices, it is easy to conceive, 1st. why they adhere intimately to the places in which they are found, and have no laxity in the integuments; 2d. why the skin approximates from all the neighbouring parts to cover the wound; 3d. why it wrinkles in approximating; 4th. why, where it yields the most, the cicatrix is the smallest, as in the scrotum, the axilla, &c.; and why on the contrary it is the largest, where it yields but little, as on the sternum, the cranium, the great trochanter, &c.; 5th. why the thickness of all cicatrices is uniformly in an inverse ratio to their width; in fact as there is only the same quantity of cellular granulations to form them, it is necessary that they should lose in one way what they gain in another; hence those that are broad are much more easily torn; 6th. why they have not a regular organization, do not partake of the functions of the cutaneous organ they replace, and why their texture is absolutely different from this organ. The cicatrization of wounds left to themselves, especially those with loss of substance, differs essentially from the union by the first intention, which is effected by the agglutination of the edges. In this last there is neither the second period, that of fleshy granulations, nor the third, that of suppuration, nor the fourth, that of sinking down. Union succeeds immediately to the first, that of inflammation.

We see, from all that has been said, that the cellular texture is the essential agent in the production of all cicatrices, that it forms their basis and their principle, that without it they could not take place, and that they depend especially upon the property it has of extending and increasing.

Influence of the cellular texture in the formation of tumours.

In the formation of cicatrices, the cellular texture grows but a few lines above the level of the place of division; the cells it forms in its reproduction are generally small. It is not so when there is a departure from the ordinary laws of cicatrization, when any accidental cause alters the vital properties; then we see a very extensive growth, which often has more of this texture than the parts from which it arises. All those different excresences, known by the names of fungous flesh, fleshy protuberances, soft flesh, &c. are but the result of this increase of the cellular system, being greater than what it should be by the ordinary laws of cicatrization; thus the cicatrices are not effected while these irregular productions continue; it is not until they are repressed that consolidation takes place. But it is especially in different tumours that we see this development, this remarkable growth of cellular texture. All the fungi, and productions that are developed exclusively in the mucous membranes, in the sinuses, the nasal cavities, the mouth and the womb particularly, and which differ essentially from those that have their seat on the fibrous membranes, the dura-mater for example, though they are compounded under a common name, all the fungi, I say, arise from the cellular texture, they are of a peculiar substance deposited there, which as it is more or less abundantly separated, leaves its primitive base more or less exposed.

Polypi, whether mucous or sarcomatous, tumours that are equally the attribute of the mucous system, have also the cellular texture for the primitive base of their organization. All the different kinds of cancers exhibit it in a manner more or less evident, in the swelling of the parts which they occasion. It would be necessary to notice almost all tumours, to point out those that the cellular texture assists to form.

We may then consider it as forming the general base, the nutritive parenchyma of almost all excrescences. It shoots up, and grows first at the part where the tumour is to be developed; then it is encrusted with different foreign substances, and their difference constitutes the difference of the tumours. These phenomena are precisely analogous to those of ordinary nutrition. In fact, all the organs resemble each other in their nutritive base, the parenchyma of nutrition, which is vascular and cellular; they differ in the nutritive substances deposited in this parenchyma. All tumours then are cellular, this is their common character. Their peculiar character is derived from the substances that the texture separates, according as the morbid alterations of which it is the seat, modify differently its vital forces and place it in relation with this or that substance; thus as we have said, all the internal cicatrices are similar in the first period, in that of fleshy granulations, and differ as the nutritive substance of the organ to which they belong, penetrates them.

Thus we see, that nature is the same in her operations, that a uniform law presides over all, and the only difference arises from the application of this law. Wherever there is natural nutrition or an accidental modification of this function, the cellular texture performs an essential part; now this important part which it has in cicatrization and the formation of tumours, arises from the singular property it possesses of extending itself, of dilating and growing. Examine the tumours that appear in the muscles, the tendons, the cartilages, &c. you will not see there an expansion of fleshy, or tendinous fibres, or of the cartilaginous substance, &c. the cellular texture alone goes from the organ and is spread in the tumour; thus the fibres of the bones, the muscles, the fibrous substances divided in solutions of continuity, are not raised above the level of the wound, as the cellular texture of the part is for the production of granulations.

The tumours of which I have spoken, have nothing in common, as has been imagined, with the acute swellings that constitute phlegmon, nor with that engorgement that the limbs experience where there is a violent irritation, as a compound fracture or luxation, a whitlow, a puncture with a poisoned weapon, &c. an engorgement that is generally seen around the whole external parts, which are violently affected; it sometimes comes on almost instantaneously, and is not really inflammatory, though there is tension, pain, &c.; it deserves rather the name of inflation than engorgement.

We must not confound these tumours with certain chronic swellings, in which, without increasing or growing, the cellular texture is infiltrated, and different substances enter it, that change its nature; such are those that take place in the diseases of the articulations; such is the callosity of fistulas, &c.; the fatty matter that is found in some tumours, &c. In all these cases there is neither growth or enlargement, as in a polypus, a fungus, &c.; it is a substance more solid than serum, that infiltrates the cellular texture, obliterates its layers, and presents a homogeneous appearance.

There is after death a great difference between an acute and chronic tumour, between that produced by growth and that by infiltration. In fact, one remains the same, and preserves, until putrefaction, its size, its form, and its density, like all the organs. The other sinks away, as I have remarked, by the loss of the vital forces. This subsidence varies; if the tumour is nothing but the cellular inflation of which I have spoken, and which is so common in external injuries, it entirely disappears; if, besides this inflation, there is an accumulation of blood, as in carbuncle, phlegmon, &c. a portion of the tumour remains, though always much diminished in size. It is generally in this inflation, of the immediate cause of which I am ignorant, that the subsidence especially takes place. Let us pass to a function of the cellular texture not less important, and which is very analogous to this.

Influence of the cellular texture in the formation of cysts.

A cyst is a membrane, in the form of a sac without an opening, which is accidentally developed, and which, containing fluids of a different nature, has been on this account divided into many species. The cysts are formed from the cellular texture; they arise in its cells, grow in the midst of them, and have all its characteristics.

To be convinced of the influence of the cellular system in the formation of cysts, it is sufficient to prove that between them and the serous membranes, there is the greatest analogy, and almost identity; for we shall see that these membranes are essentially cellular. The following are some of the analogies of these two kinds of productions, the one of which is natural and the other accidental.

1. Analogy of conformation. The cysts form all kinds of sacs without an opening, containing a fluid that is exhaled from them, having a smooth, polished surface contiguous to this fluid, an uneven, loose one, continuous with the neighbouring cellular texture.

2. Analogy of structure. Always formed of a single layer, like serous membranes, cysts have like them a cellular texture, as is proved by maceration and inflation. Thus they constantly arise in the midst of the cellular organ, usually where it is most abundant. Few blood-vessels enter them; the exhalant system is conspicuous there.

3. Analogy of the vital properties. There is no animal sensibility in them in an ordinary state, but it is very evident in inflammation; organic sensibility is always remarkable in them, and tone, which is characterized by a slow and gradual contraction, in consequence of the artificial or natural evacuation of the contained fluids, &c.; these are the characters of cysts, they are also, as we have seen, those of serous membranes.

4. Analogy of functions. Cysts are evidently secretory or rather exhalant organs, which exhale the fluid they contain. Exhalation becomes very evident there, when after the evacuation of the fluids, the membranous sac has not been removed, or an artificial inflammation excited in it. Absorption is proved, in the spontaneous cure of encysted dropsies, a cure which must depend on this function alone.

5. Analogy of affections. Who does not know that between the dropsy of the tunica vaginalis and the encysted dropsy of the cord, there is the greatest analogy; that the curative means are the same, that in both cases the inflammation that is produced by the injection of a foreign fluid, wine, for example, is the same, and that the cure is effected by a similar mechanism? Whoever has opened two bodies, each having one of these affections, and examined the sacs in which the fluid is contained, must have perceived that their appearance is precisely the same. Remove the fluid from the cyst of a soft wen, and you will discover but little difference between it, dropsical cysts, and serous membranes.

The preceding considerations induce us to admit a perfect resemblance between cysts and serous membranes, of whose characters they partake, and into the system of which they essentially enter, and consequently into the cellular system. It is very probable that there is a relation between them, and that when a cyst is formed and exhales copiously, the exhalation of the serous membranes is diminished; this does not, however, rest upon direct proof. There is this essential question, how are these cysts developed? How a membrane, which does not exist in a natural state, can arise, grow, and even acquire a very considerable development under certain circumstances. This problem is usually resolved in the following manner; at first, it is said, a small quantity of fluid collects in a cell; this fluid increases and dilates in every direction, the parietes of the cell, which are attached to the neighbouring cells and thus increased in thickness. Gradually this fluid, serous in dropsy, white and thick in steatoma, &c. increases in quantity, presses in every direction the sac that contains it, enlarges, crowds against the neighbouring organs, and thus acquires the form under which we see it. Nothing at first sight appears more simple than this mechanical explanation; nothing is less conformable to the process of nature. The following considerations will serve to prove this. 1st. The cysts are analogous in every point of view to serous membranes; how then could they have a different origin from these membranes, which are never formed, as we shall see, by the compression of the cellular texture? 2d. Does an origin thus mechanical, in which the vessels compressed against each other would inevitably be obliterated, as we see the skin become callous, accord with the exhaling and absorbing function of the cysts and with their peculiar kind of inflammation? 3d. Why, if the cells adhering to each other, form these unnatural sacs, is not the neighbouring cellular texture diminished and destroyed, even when they acquire great size? 4th. If, on the one hand, the cysts are formed by the compression of the cellular texture, and if it is true on the other, as we cannot doubt, that their fluid is exhaled by them, it is necessary to conclude then, that this fluid pre-exists in the organ that separates it from the blood: I would as soon assert that the saliva pre-existed in the parotid, &c.

The immediate consequence of the preceding reflections, I think, is, that the common explanation of the formation of cysts, is directly opposite to the general course that nature pursues in her operations. How, then, do these sacs arise and grow? these tumours that appear externally, or are developed within; for there is no difference in these two sorts of unnatural productions, except in the form. Most tumours throw from their external surface the fluid that is separated there. A cyst, on the contrary, exhales this fluid by its internal surface, and preserves it in its cavity. Suppose a fungous, suppurating tumour, suddenly becomes a cavity, and suppuration is carried from the external surface to the walls of this cavity; this will be a cyst. On the other hand, suppose a superficial cyst, the cavity of which is obliterated, and the fluid of which is exhaled upon the external surface; this will be then a suppurating tumour.

As the form, then, establishes the only difference between tumours and cysts, why should not the formation of one be analogous to that of the other? Surely, no one ever thought of attributing to compression, the formation of external or internal tumours. We may conceive of the production of cysts in the following way; they begin to be developed and grow in the midst of the cellular organ, by laws very analogous to those of the general increase of our organs, and which seem to be aberrations, and unnatural applications of these fundamental laws, of which we are ignorant. When the cyst is once characterized, exhalation commences; at first scanty, it afterwards increases as the cyst grows. The increase of the exhalant organ, then, always precedes the accumulation of the exhaled fluid, so that other things being equal, the quantity of suppuration in a tumour is in a direct ratio to its size.

ARTICLE SIXTH.
DEVELOPMENT OF THE CELLULAR TEXTURE.

I. State of the cellular system in the first age.

In the first periods after conception, the fœtus is only a mucous mass, homogeneous in appearance, and in which the cellular texture seems almost exclusively to predominate. In fact, when the organs begin to be developed in this mass, the spaces that are left between them are filled with a substance which, exactly similar to that which before formed the whole of the body, can be considered as the residue of it, or rather perhaps it exists in a distinct manner, because it has not been penetrated with the peculiar nutritive substance, like that which forms the parenchyma of nutrition of the organs, which before this penetration resembled it precisely. This substance that lies between the organs, and which is the principle of the cellular texture, is the farther removed from a fluid state, as the period of labour approaches. First it is a true mucus, then a kind of glue, then the cellular texture begins to appear.

This primitive state of the cellular organ, this appearance that it has at first, is owing to the great quantity of fluids that enter it at that period; it does not denote an inorganic existence; we can then compare it to the vitreous humour, which appears wholly fluid at first sight, because the transparency of its layers do not permit us to see them in the humour that enters its cells; make a puncture so as to evacuate this humour, and they become evident.

Thus the cellular texture, extremely fine and even transparent in the first periods of life, is then concealed by the humour that fills it, and becomes more sensible as this humour diminishes with age. This phenomenon sometimes takes place in after life, in different serous infiltrations, those especially in which the infiltrated fluid has some viscidity.

What is this humour that is so abundant in the cellular system, in the first months after conception? Is it albuminous like that which afterwards lubricates it? Probably it is; I should think, also, that it has much of the character of gelatine, a character which predominates, we know, in the animal humours at this period; I know of no experiment upon this point. Whatever the humour is, it is much more viscid and unctuous than it is afterwards; the touch is sufficient to convince us of this. It is its predominance, joined to the delicacy of the cellular layers, that, in the first months, makes every attempt to render the fœtus emphysematous, by blowing air under the skin, almost absolutely useless.

At birth and some time after, the great quantity of sub-cutaneous fat makes artificial emphysema very difficult; it does not appear that the fœtus ever has a natural one. The delicacy of the cellular layers and filaments is such at this period, that the imagination cannot represent it; the texture of the hair is gross in comparison with it. I presume that the ball of fat, which I have said almost always exists in the cheek of the fœtus, arises from a rupture of several layers, a rupture from which is produced a great cell, that is filled with fat.

Sometime before birth, at that period and in the subsequent years, the cellular humour constantly diminishes; the cells become dryer, consequently more apparent; the whole mass of the cellular system diminishes, because as the organs increase, the interstices are contracted. This system however predominates for a long time over the others; hence the roundness of form that characterizes the infant, the want of prominence of its organs, that are almost concealed by it; hence in part the suppleness and multiplicity of its movements; hence also the frequent diseases of which it is the seat at that age.

The layers still preserve an extreme delicacy; they are still easily broken. In producing emphysema, upon very lean children, I have observed that often it forms in places very considerable dilatations, a kind of sacs in which the air accumulates in large quantity, and which arises from this rupture; whilst in the same experiment upon an adult, the air is propagated in an uniform manner and constantly infiltrates the cells without destroying them. By comparing in our slaughter-houses, the flesh of calves blown, and that of oxen in the same state, I have sometimes made an analogous observation.

In infancy and in youth, the vital energy of the cellular texture is very conspicuous; at this age, the fleshy granulations, essentially cellular as we have seen, arise more promptly and go through their periods more rapidly than at any other age; the union of wounds is easier; and all tumours, have in their development and their progress, a rapidity that particularly depends upon the high degree to which the vital forces of the cellular system are raised at this period. It is to the same cause, that must be referred the facility of absorption of serous fluid, which sometimes infiltrates accidentally the cells, as we see in the scrotum, the eye-lids, &c.; the suddenness of the formation of cysts, &c.; then dropsies are much less frequent. When they do take place, why are the superior extremities almost as often affected as the inferior, whilst the leucophlegmasia of adults commences almost always in the last? This is then as remarkable a phenomenon, as the singular tendency that there is in the legs of being infiltrated, compared with the arms. Does not this depend upon situation, which, forcing the lymph to ascend against its weight, gradually weakens the absorbents when it has continued for some time? This explains, why varices are, as we know, more frequent in the inferior than superior extremities.

II. State of the cellular system in the after ages.

In the adult, the cellular texture is condensed and becomes firmer; its layers have a more compact texture. It appears also to lessen in quantity, because as the organs increase in thickness, their interstices are contracted. If there is not a real diminution, there is at least one in comparison with the state of the organs. It is to this circumstance that must be attributed in part, their prominence under the integuments, the striking appearance of the form of the muscles, &c. It appears besides, that the quantity of cellular texture varies according to temperaments; that in those called phlegmatic or lymphatic, it predominates over the other systems, and in the bilious, which is characterized by a dryness and rigidity of fibre, it is in the smallest proportion. In women, it is in larger quantity than in men; the roundness of their forms is in part the result of this.

The motion of a part appears to have no effect in producing a more active nutrition of its cellular texture, as takes place in the muscles, the nerves, and sometimes even in the blood-vessels.

In old age this texture is condensed and contracted; it acquires consistence and hardness. The teeth tear it with difficulty in the boiled flesh of old animals; like it, it is tough and requires long boiling to soften it. Much less fluid is exhaled there, hence a sort of dryness and rigidity, that render the motions of old age difficult. A kind of withering, that it experiences, contributes essentially to the general diminution that the body then undergoes. It loses its vital forces; hence its laxity, that prevents it from supporting the skin as usual. This becomes every where loose, dependent even in some places, in which it forms folds. The scrotum has no longer the power of contracting that characterized it and which it derived from the forces of the cellular system. This general relaxation, this sort of flaccidity is the constant attendant of old age, in individuals even in whom excess of all kinds, or a primitive disposition, have rendered this age premature. I saw at the Medical Society a dwarf, sixteen years of age, hardly two feet high, who had already begun to grow old; his sub-cutaneous texture had that laxity, that does not belong to his age. The premature decrepitude of the dwarf of the king of Poland, exhibited the same phenomenon. Two persons who lived a long time with him informed me, that at his death, there was externally this relaxation and flaccidity of integuments, of which the subjacent cellular texture appears to be the seat.

It is rare in old age to find osseous incrustations in the cellular texture. In the great number of old persons that I have had occasion to dissect, or to have dissected, I remember to have seen but one, and that occupied the posterior part of the mesentery. I have seen some others in adults, especially in women, in whom they are found frequently, in the cellular texture that separates the womb from the rectum; I have preserved several specimens of these.