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.
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.
The cellular system, like almost all the others, is composed of a peculiar texture and of common parts.
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.
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.
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.
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.
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.
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.
The properties of texture are strongly characterized in the cellular system.
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 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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.