Part 20

Though the secretions are not active in the fœtus, the glandular system is in general much developed. All the salivary glands and the pancreas are larger in proportion than afterwards; the liver is enormous; and the kidneys have a size much greater in proportion than they have in the adult. The same probably is true of the mucous glands, though I have not made any very precise researches upon this point. The form is different in many; the kidney for example is evidently uneven, whilst afterwards its surface is almost smooth. The colour is not the same; this is particularly striking in the salivary and lachrymal glands. These glands which are white in the adult, have in the fœtus an extreme redness which they lose by washing, which is not owing to the blood circulating in their vessels, though there is much of it in their vessels, but it is really inherent in their texture. This colour is never as great in the pancreas, though its texture is nearly the same. The texture of the glands is extremely soft and delicate at this age, which is the case with all the parts. They are divided and yield with great ease, and their vessels, which are large, carry into them a very great quantity of fluid.

Then they are, if we may so say, in a state corresponding with that of remission in the adult; they secrete even less fluid, though they appear however to be in constant action. In fact, all the reservoirs would be insufficient to contain their fluids, if in a given time, as much flowed from them as after birth. Is this because the black blood, which then enters their parenchyma, is unfit to furnish the materials of the secretions? This may have an influence, and I have elsewhere imagined it, from the circumstance that this blood is unable to support many other functions. But the principal reason appears to me to be, that in the fœtus the nutritive motion of composition predominates evidently over that of decomposition, which is very inconsiderable. Almost every thing which arrives in the organs remains in them and continues to furnish the materials of the rapid growth which is then taking place in the body; now, the secretions being principally destined to carry off the residue of nutrition, must then be very inactive.

Besides, digestion does not introduce into the blood any of those principles which, being useless to nutrition, must on this account go out as they entered, that is to say without making a part of our organs; such are for example most of the drinks, which only pass into the mass of blood, and go out immediately with the urine.

The glands of the fœtus are then like the brain at that age; though much developed, they remain inactive; they are in the expectation of action.

II. _State of the Glandular System during Growth._

At birth, the glandular system increases suddenly in energy; it takes a life which until then was foreign to it, and begins to pour out more fluid. It owes this change, 1st, to the difference of the blood which enters it, and which till then black and consequently venous, then becomes red and charged with principles that are new to it; 2d, to the general and sudden excitement carried to the extremity of all the excretories, by the aliments to those which open upon the canal that extends from the mouth to the anus, by the air to the mucous ducts of the bronchial and pituitary surfaces and to the lachrymal gland, by the various frictions of the extremity of the glans penis and even by the air which acts also upon it, to the kidneys and the bladder.

All the glands are so much the more sensible to this sudden excitement, as they are unaccustomed to it. Their sensibility, heretofore torpid, is roused; they feel the contact of the blood which enters them and which till then had made only a feeble impression upon them. This sensation is so much the more acute, as on the one hand the organic sensibility of the glands becomes more evident, and as on the other the red blood is a more powerful stimulus than the black; for, as I have already had occasion to observe, the blood that arrives in an organ produces two effects in it, one of which is to excite it, either by the motion it communicates, or by the contact of the principles it contains, and the other is to furnish materials for the different functions, as for exhalation, secretion, nutrition, &c. The first effect is common to all the organs which the blood enters; the second is peculiar to each.

I would observe however that many of the secretions are much less active during the first years, than they are afterwards; such are those of the salivary glands, the liver, &c. The kidneys being destined to throw out the residue of digestion, as much and more often than that of nutrition, are in a state of activity in proportion to that of the first function. The infant often passes urine, as he frequently voids excrements. It is not because many substances, returning from the organs which they have nourished, present themselves to the kidneys, to be thrown out by this part.

The affections of the glandular system are not the predominant ones in early age. 1st. It is not the parotids that are enlarged in the frequent swellings that take place in their neighbourhood, but it is almost always the lymphatic glands. 2d. We know that an excessive flow of bile, and the affections which arise from it, are then very rare. 3d. All the secretions relating to generation are absolutely nothing. 4th. In the same proportion in which the organic affections of the liver and the kidneys are common in the adult, are they rare in the infant. Then it is in what are improperly called lymphatic glands, in the brain, &c. that the morbid anatomist finds materials for his researches; for observe that the organs which are particularly in action in one age, are those which are most often attacked by acute and chronic diseases at that age, and that on the contrary they seem to forget those in which but little is done. 5th. Surgeons know that sarcoceles, hydroceles by effusion, varicoceles and all the diseases of the testicles are as rare before the period of puberty, when nutrition only is going on in these glands, as they are common in the subsequent years.

It appears that it is the mucous glands which are then the most commonly affected and are consequently in the greatest activity. The lachrymal glands are also very frequently in action. The infant weeps more often than the adult; we might say that all the passions which agitate this age have but one uniform mode of expression, and this mode is weeping. If the infant suffers, if he is jealous or frightened he weeps; if he is furious, he weeps because he is not very strong. This influence of the passions upon the lachrymal gland in the early years, seems to take place at the expense of the influence exerted upon the other glands. It is rare that fear or fright give to infants a sudden jaundice, or that they excite bilious secretions. At this age they do not pass water and void their excrements from fright as often as in the after ages; they have not the spasmodic vomitings that are so frequently occasioned by the passions of the adult; they do not become pale or red as much in anger; thus the countenance is not to the same extent the moveable picture upon which is painted the emotions of the mind. The eye does not sparkle in anger and is not expressive in friendship. It is the lachrymal gland which then most often serves in the face, for the expression of the passions. Observe that this expression is that of weakness and want of power, it is that of woman, who resembles the infant in so many phenomena. The feeble stag opposes his tears to the dogs, who seize upon him to devour him.

The glandular texture remains for a long time soft and delicate in the infant. At birth and in the fœtus, neither the liver nor the kidneys have the singular property of hardening by boiling. They remain during this experiment very tender and yield easily to the least impression. If the boiling be ever so long continued, they do not lose this character, which is gradually weakened as we advance in age, and which at this period makes the glands fit for some uses in our kitchens to which they are not so proper in the adult.

III. _State of the Glandular System after Growth._

Puberty commences about the period that growth finishes. A gland till then inactive in man, enters suddenly into activity. The prostate follows it in its development. In woman the breasts swell, separate, and acquire in a short time a size which they would not have done in many years, if they had grown according to the same laws as in the preceding state. The other glands, far from being weakened, in proportion as these become stronger, increase their action also; they become stronger, and gradually lose the softness that characterized them in infancy; they moreover grow harder.

Till then composition had predominated over decomposition in the general nutritive motion. Then almost as many substances are constantly thrown from each organ, as enter its interior to nourish it. Now as the glands are the great emunctories which throw out the residue of nutrition, they then pour out more fluids in proportion than before.

During youth it is the genital glands which predominate over the others; they seem to be a centre whence go irradiations that animate the whole machine. We might say most often that they are, in the mechanism of our moral actions, the spring which puts every thing in motion.

As we recede from youth, the influence of the genital glands becomes weaker, because they are in less activity. Towards the thirty-sixth or fortieth year, it is especially the glands destined to digestion which predominate over the others, and among these the liver in particular seems to be in activity. Then the bilious affections are predominant; then the passions to which the bilious temperament seems to dispose us, more frequently agitate the mind. Ambition, hatred and jealousy are often the sad attendants of this age. These passions are then more durable. The levity of youth and the passions arising from the influence of the genital glands, which predominate at this age, had for a time suppressed these, or rather had prevented them from being developed. Then they remain alone, the others having escaped in smoke with the fire of youth. Then also the influence of the lively emotions of the mind affects especially the glands and the abdominal viscera. Then is felt that contraction at the epigastric region, the painful effect of the bad passions; jaundice occasioned by sorrow is then more frequent.

This age is that of the organic affections of the glands, of all the numerous changes of texture, of all the excrescences which destroying as it were the nature of these organs, transform them into bodies of a different texture. In infancy, leucophlegmasia is most often produced by an engorgement of those lymphatic bunches that are called glands, which resembles tabes mesenterica, the engorgement of the bronchial glands, &c. In the adult on the contrary, it is with the diseases of the liver, of the spleen, of the kidneys, that it is most often seen.

IV. _State of the Glandular System in Old Age._

In old age, the glands become more firm and hard. Before that period even, the glandular system of animals ceases to be used at our tables. The liver, the kidneys, the spleen, &c. are mixed with the fleshy texture in common boiled meat, only to communicate to it some salts, some savoury principles that are foreign to this texture. They are not eaten, or at least they are not agreeable to the taste. The lungs which contain so great a quantity of mucous glands, do not afford a very digestible aliment except those of the calf; those of the ox are not brought to our tables, especially when the animal is old. I would observe upon this subject that the muscular and glandular systems are in an inverse order as it respects digestion, at least in the stewed state to which they are reduced for nourishment. In fact, the glandular system has not an agreeable taste and is not very digestible except in young animals, whilst at this age the muscular is insipid, and does not become savoury food till towards the middle of life.

In extreme old age, the colour of the glands changes less than that of most of the other organs. We find the liver, the kidneys, &c. almost as full of blood as in the adult; they are as red, whilst the muscles pale and colourless announce by their appearance that but little blood enters them at the latter periods of life. We might say that this fluid first abandons the skin and the muscles of animal life which in the trunk are subjacent to it, and which in the extremities are found very distant from the heart, or at least that it diminishes much in the two systems, and is concentrated in the organs in the neighbourhood of the heart; thus the secretions are still very abundant in old people, whilst the muscular, nervous forces, &c. are considerably weakened. The kidneys still secrete much urine; the liver pours out much bile, though this gland loses in part the kind of predominance it exercised in the economy towards the fortieth year. We know that the very frequent catarrhs that then take place, indicate an increase of action in the mucous glands. The functions of the testicles and mammæ have long since ceased.

The activity of the glands remaining in exercise, appears to be owing to two causes. 1st. The decomposition being very great at this age, many substances are presented to the glands to be thrown out. An old person decreases by a phenomenon opposite to the rapid growth of the fœtus, in which the glandular system throws out scarcely any thing from the economy. 2d. The skin having the horny hardness and being contracted, ceasing in part to be an emunctory of the products of decomposition, the glands supply the place of these functions. The cutaneous and glandular systems are then in the same relation as in winter and in cold countries, in which, we have seen, that the second constantly supplies the place of the first.

In general, the glandular system is one of those in which life is the most slowly extinguished. In the dead bodies of old people we find the bile still filling the gall-bladder, the bladder full of urine, &c. All the glands when compressed, the prostate itself, permit a large quantity of fluid to escape from their excretories. I have even observed that in this compression, we uniformly press out more fluid in an old subject than in a young one. The older the animals are, the more their kidneys, as we know, preserve the urinous smell. The lungs, which abound so much in mucous surfaces and consequently in mucous glands, are not withered and have not the horny hardening in old age; they perform their functions as regularly as in youth.

In general it is a very remarkable phenomenon that all the principal internal organs, the liver, the kidneys, the spleen, the heart, the lungs, &c. still preserve a very considerable vital force, whilst the sensitive and locomotive organs already almost exhausted, have broken in part the communications which connect the individual with the objects which surround him.

DERMOID SYSTEM.

All animals are covered with a more or less compact membrane, of a thickness in general proportioned to the size of their body, destined to defend the subjacent parts, to carry out a considerable portion of the residue of nutrition and digestion, and to place it in relation with external bodies. It is in man a sensitive boundary, placed at the extremity of the domain of his mind, where these bodies continually touch, for the purpose of establishing the relations of his animal life, and of thus connecting his existence with that of every thing which surrounds him. This covering is the _dermis_ or skin. We shall call the whole of it the Dermoid System.

ARTICLE FIRST.

FORMS OF THE DERMOID SYSTEM.

The covering which forms this system, being proportioned to the parts that it covers, is applied to these parts, adapted to their great inequalities, and allows the largest external prominences to be visible, but conceals a great number on account of their small size; thus the appearance of the body stripped of skin differs very much from that with the skin on.

This covering everywhere continuous is reflected through different openings in the interior of the body and goes to give origin to the mucous system. The limits between the two systems are always marked by a reddish line; within this line is the mucous system, without it the dermoid. Yet the demarcation is not as striking in the organization as in the colour. Both are confounded in an insensible manner. In the neighbourhood of these openings, of those of the face especially, the dermoid becomes more delicate. At the commencement of these openings, the mucous borrows more or less, as I have said, the characters of the first.

I. _External Surface of the Dermoid System._

This surface, everywhere contiguous to the epidermis, is remarkable for the hairs which cover it, for the oily fluid which constantly lubricates it, for the sweat that is deposited on it, for the sense of feeling of which it is the seat and which the internal surface does not possess. We shall in this article consider only the external dermoid forms, without regard to these different objects.

We see upon this surface different kinds of folds.

1st. Some are owing to the subjacent muscles which, being intimately connected with the dermis, forming almost a part of it, wrinkle it when they contract. Such are the wrinkles on the forehead; those in the form of rays which the orbicularis produces around the eye-lids, &c.; those of which the cheeks are the seat, when the great and small zygomatic, &c. contract; those which the orbicularis of the lips produces around the mouth, when it contracts it by diminishing its opening, &c. All these folds are owing to this, that on the one hand the skin cannot contract like the muscles, and that on the other it is necessary that it should occupy less space in length at the instant these are shortened. They are of the same nature as those of which the mucous surfaces, that of the stomach in particular, become the seat in the contraction of the fleshy layer which is contiguous to them. Thus the direction of these folds is always perpendicular to that of the subjacent muscles whose fibres they cut at a right angle. We are accustomed to attach much importance to the existence of these wrinkles in the expression of the passions; no doubt because then they are strongly marked. In fact the breadth of the face of man makes it well adapted to their development, whilst that of animals is badly formed to produce them. Thus their eye, rather than the features of the face, is the moveable picture which is differently sketched at every instant by the various feelings of anger, hatred, jealousy, &c. The wrinkles of the human face contribute very much to the expression of the countenance, they compose in part the physiognomy, and mark its different shades.

The wrinkles of the scrotum are analogous to these; they depend upon the contraction of the subjacent cellular texture, in which some fleshy fibres appear also to exist.

2d. There are other wrinkles which are owing also to the motions, but not to those of the subjacent muscles. There are those of the sole of the foot, and especially those of the palm of the hand. There is not there any sub-cutaneous muscle adhering to the skin, except the small palmar muscle, which has no agency in these wrinkles that are formed at the places where the skin is constantly folded in flexion. Thus there are many of them about all the articulations of the phalanges. In the palm of the hand, we see three principal ones, one at the base of the thumb, produced by the motion of opposition, another at the anterior part of the palm, occasioned by the flexion of the four last phalanges which are bent towards the thumb, and the third is found in the middle of the palm. The dermis is folded between these depressed lines, in the motions in which the hand is hollowed. Many other small folds corresponding with less evident and less frequent motions, cut these at different angles.

On the back of the foot and hand, there are many wrinkles about each articulation of the phalanges, when they are extended. They disappear in flexion, and are owing to this, that nature, on account of the motions, has made the skin more loose at this place, and broader in proportion to the parts it covers. About most of the articulations, there are analogous folds, but they are much less evident, because the skin adheres less to the neighbouring parts. Upon the whole trunk, the arm, the fore-arm, the thigh and the leg, we see no depressions but those from the muscular prominences.

3d. There is a third species of wrinkles, or rather cutaneous impressions, which are not very evident, found especially on the sole of the foot and the palm of the hand and which we easily distinguish from the preceding; they are those which indicate the rows of the papillæ. The surface of the trunk presents hardly any thing similar.

4th. Finally, there are the wrinkles of old age, which are of a wholly different nature. The sub-cutaneous fat having in part disappeared, the skin becomes too large for the parts it covers; now as it has lost with age its contractility of texture, it does not contract, but folds in various directions. Thus where there was the most fat, as on the face, these wrinkles are the most evident, they resemble those that appear on the abdomen after several pregnancies, dropsy, &c. In young people, if emaciation takes place suddenly, the skin contracts, and no wrinkle is formed.

II. _Internal Surface of the Dermoid System._

This surface answers everywhere to the cellular texture which is loose upon the trunk, the thighs, the arms, &c. and which is condensed upon the cranium, the hand, &c. In most animals, a fleshy layer called panniculus, and of a form analogous to that which is almost everywhere subjacent to the mucous system of man, separates the skin from the other parts, and communicates to it various motions. In man, the dermoid system exhibits here and there traces of this internal muscle, as is observed in the platysma myoides, the occipito-frontalis and most of the muscles of the face. There is nothing similar on the trunk, extremities, &c. Man is as much inferior in this respect to most animals, as he is superior by the arrangement of his facial muscles. Thus observe that whilst in him all the passions are painted as it were upon the face, and the whole exterior of the trunk remains calm in these tempests of the mind, this exterior is convulsively agitated in animals. The mane of the lion becomes erect, the whole skin of the horse moves, a thousand different agitations animate the exterior of the trunk of animals, and make it a general picture on which is painted all that passes in the interior. You can determine from behind, in many animals, by seeing only their bodies, that they are agitated with passion; cover the face of man, the curtain is drawn over the mirror of his mind; thus almost all nations leave it uncovered. The physiognomy is in this respect, if we may so say, more generally spread over the exterior, in animals with a fleshy panniculus.

Besides the cellular texture, the dermis is almost everywhere subjacent to the muscles in the trunk; but, foreign to the motions of these muscles, it receives no sensible influence from them. In the extremities it is found separated from the fleshy layers by aponeurotic expansions. Many vessels wind under it; the great veins pass through its texture; many arterial ramifications go upon its surface, and many nerves between these ramifications.

ARTICLE SECOND.

ORGANIZATION OF THE DERMOID SYSTEM.

I. _Texture peculiar to this Organization._