Part 18

The great arterial trunks winding in the glands, communicate to them an internal motion very favourable to their functions. This motion is so much the more evident, as almost all these organs very near the heart by their position in the trunk, are, if we may so say, under the immediate jar of its contractions. The salivary glands, the mucous ones of the mouth and the lachrymal on the one hand, the testicle, the prostate and the mucous ones of the genital parts on the other, exhibit the extremes of this position. Another cause which favours the jar of the glands by the entrance of the blood, is that almost all the arteries that go to them run but a very short course before they enter them. The spermatic alone is an exception to this rule; thus, every thing in the secretion of semen seems to be characterized by a remarkable slowness. To this constant motion imparted to the glands by the entrance of the blood, should be added that which is communicated to them by the neighbouring organs, and which keeps them in a constant excitement, which is more necessary to their secretion than to their excretion. In considering the action of organs, the constant motions with which they are agitated has been too much neglected. The example of the brain ought however to fix the attention of physiologists upon this point.

The veins, everywhere continuous with the arteries, follow the same distribution in the glandular system, and accompany them almost everywhere. We do not see superficial and deep-seated veins, as we do in many other organs. The liver is the only example in which the red blood enters at one side, and the black goes out at the opposite.

Most of the veins of the glandular system pour their blood into the general system of black blood, and as many glands are very near the heart, they feel the reflux which this system often experiences. This phenomenon is particularly remarkable in the liver, as the hepatic veins open but very little below the right auricle. Hence why whenever this auricle is considerably distended, as in asphyxia and in death in which the lungs being crowded present an obstacle to the blood, the liver has a much greater quantity than usual. I have uniformly made this observation. Weigh comparatively this organ when the auricle is full and when it is empty in the dead body, after having first tied all its vessels; you will find a very great difference. For the same reason, you will observe a constant relation between the weight of the liver and that of the lungs, provided a morbid alteration of texture of one of them be not the cause of death. The veins of many glands, as those of the mucous ones of the stomach and the intestines, as those of the prostate, &c. pour their blood into the system of abdominal black blood. There are hardly any in the system of which we are treating, but these veins, those especially of the glands situated in the pelvis, which become varicose. Varices of the prostate are frequent, as we know.

_Of the Blood of the Glands._

The quantity of blood that is constantly found in the glands varies remarkably; they may even be divided in this respect into three classes. 1st. In the pancreas, the salivary, lachrymal glands, &c. there is found but very little. It does not furnish the colouring matter to these organs, which are white, and which, when macerated, tinge with red but two or three waters. 2d. In the mucous glands, the prostate, the testicles, and the amygdalæ, there is found a little more. 3d. The liver and the kidneys contain so great a quantity of it, that there is not in this respect any proportion between them and the rest of the glandular system. This is owing in a small degree in the first to the cause pointed out above; thus it often contains more than the second, but it is not the essential cause. After death by hemorrhage in which there was no reflux, in the liver or the kidney suddenly taken from a living animal, &c. we observe the same thing. In macerating these glands, it is necessary to renew the water at least a dozen times before it ceases to be bloody. Hence why when they are preserved in alkohol on account of an organic disease of which they were the seat, they must be first macerated for a long time; if not, the liquor soon becomes turbid from the blood. It is this quantity of blood which gives to these glands a greater weight in proportion than that of the other parts. It is from this that their redness is derived, a colour which no other part exhibits to the same degree, but which is not more strongly inherent in their texture, than it is in the mucous surfaces or the muscles. In fact, we remove it with the same ease by repeated washing. Then the liver assumes a greyish appearance, which appears to be the colour inherent in its texture, as white is that of the fleshy fibre. The kidney seems a little less to derive its colour from the blood. It remains in part red when macerated; the pulp even which is the product of it, after remaining some months in water, that has been often changed, still exhibits in some degree this colour, much less however than in a natural state.

Does the state of the secretions make the quantity of the glandular blood vary? Does more of this fluid enter the kidney when it furnishes much urine, than when it secretes but little, or if the same quantity is brought by the arteries, is less returned by the veins in the first than the second case? This is an interesting subject for experiment.

Is the nature of the blood changed when it arrives at the glands? Has it a peculiar composition before entering each of them? Much has been said of this change necessary to secretion; but that this may take place, there must be a cause to produce it; now what is this cause here? Does not the blood circulate in the trunks which go to the glands, as in the others? It would be necessary then that the gland should be surrounded with an atmosphere which acts upon the blood at a certain distance from the place where it is; a vague idea, which has no solid foundation, and which is met with only in the books of those who have never made experiments. I have drawn blood from the carotid, spermatic, hepatic and renal arteries; it is equally red and coagulable. In the same animal, it is impossible for the senses to discover the least difference.

I would observe that secretion differs essentially from nutrition in this, that it always draws the materials of its fluids from the red blood, whereas the second often takes its own from the white fluids, as we see in the tendons, the cartilages, the hair, &c.

_Nerves._

The glands receive two species of nerves. 1st. The cerebral are found almost exclusively in the salivary and lachrymal glands, the amygdalæ, &c. 2d. The testicles, the prostate gland and the liver receive them in an almost equal proportion from the brain and the ganglions. 3d. The kidneys and most of the mucous glands receive scarcely any but those of the ganglions. What is now said of the nerves should be understood only of those that are free and independent of the arteries; for each arterial trunk that enters a gland, is surrounded by a nervous net-work belonging to the system of the ganglions, which is very evident in the great glands, as in the liver and the kidneys where this net-work comes from the semilunar ganglion, in the salivary glands where it comes from the superior cervical, in the testicles where it comes from the lumbar ganglions, &c.

Compared with the size of the glands, the nerves are in small proportion, notwithstanding what Bordeu has said. It is not necessary in fact to judge of this proportion by those of the parotid and sub-maxillary glands, which merely pass through these glands without stopping in them, and leave only some branches there. For example, there is certainly no organ in the economy, among those which receive nerves, that, in proportion to its size, has so few as the liver.

Besides, the nerves enter the glands nearly in the same way as the blood-vessels, that is to say, 1st, on all sides, in those that have no membrane; 2d, by a groove only in those that are covered with one. They divide and subdivide after entering it, and are soon lost sight of. Ganglions never exist in the interior of the glands.

Have the nerves an influence upon secretion? It is probable they have, as every gland is provided with them; but they by no means exert so immediate an influence upon this function as many physicians have pretended. 1st. It is said that the nerves of the parotid glands have been cut, and that the secretion of the saliva has been suppressed. This division is evidently impossible, since the gland must be extirpated before removing its nerves. 2d. I have divided the nerves of the testicle of a dog, the only gland in which this experiment can be made. I could not obtain any result, because an inflammation of the gland came on and it suppurated; but this suppuration even supposes that the nervous influx is not actually necessary for secretion, since suppuration is accomplished by a mechanism analogous to that of this function. All physicians know that a paralyzed limb can inflame and suppurate. 3d. Erection and the ejection of semen take place in paralysis of the lower half of the body, in which at least the nerves of the prostate gland are completely paralyzed. Mr. Ivan related to me the case of a soldier who took gonorrhœa in this state. 4th. We know that when the bladder is perfectly paralyzed and its nerves have no longer any action, its mucous glands still continue to secrete their fluid so as even to produce a catarrh. 5th. The nostril of the affected side in hemiplegia is as moist as usual. The ear of this side has its ordinary quantity of wax. 6th. In paralysis of the uvula, the action of its glands continues. 7th. When the eighth pair of one side of a dog is cut, the bronchia is found some days after to contain as much mucus as common. 8th. During the convulsions of the different parts in which there are glands, and when consequently the nerves of these glands are more excited, their secretion is not increased. 9th. If we weigh the proofs given by Bordeu of the influence of the nerves on secretions, we shall see, that they either rest upon false facts, like those of the section of the nerve, of sleep, &c. or upon vague data. In general physicians attach no precise idea to the term _nervous influence_; the habit of experimenting shows how much they have abused it. When a nerve being cut, paralyzed or irritated in any manner, the organ which receives it undergoes no derangement in its functions, we certainly are unable to appreciate the nervous influence upon this organ. I do not say that it does not exist, but I maintain that we know nothing about it, and that we ought not to employ at hazard a word to which we cannot attach any precise idea. What word will you employ then to express the influence of the nerves upon the organs of the senses, upon the voluntary muscles, &c. if the same one is used to express an action which has no relation with this, and which perhaps even does not exist?

_Exhalants and Absorbents._

This kind of vessels is but little known in the interior of the glands, where they perform only the purposes of nutrition.

ARTICLE THIRD.

PROPERTIES OF THE GLANDULAR SYSTEM.

I. _Properties of Texture._

These properties are in general very inconsiderable in this system, which appears to me to be particularly owing to its non-fibrous texture. In fact, in order to be elongated and afterwards contracted and preserve their integrity, it is necessary that the particles of an organ should possess a certain degree of adhesion and cohesion; now, it is to the fibre that especially belongs this double attribute. Observe also that the glandular system is subjected to much less frequent causes of distension and contraction, than the systems with distinct fibres. It is scarcely ever found distended except when purulent deposits, serous, steatomatous collections, &c. are formed in its interior, as often happens in the middle of the liver, kidney, &c.; now in these cases it does not yield like the skin, the muscles, &c.; its particles are separated; it is the cellular texture with which they are surrounded that is uniformly dilated; the glandular texture is even soon destroyed. It is very evident when the collections are formed near the convexity of the glands; if the tumour be at all large the texture of the organ disappears; there remains only a cellular and membranous cyst. Hydatids so frequent on the exterior of the kidneys present us with examples of it. If it is in the middle of the gland that the cyst is formed, the destruction also takes place, but it is much less evident.

A strong proof of the small degree of extensibility of the glands, is what takes place in the liver in dead bodies. I have said above that it is more or less loaded with blood, according as the system with black blood had been more or less embarrassed in the last moments. Now whatever may be the quantity of blood it contains, its size remains nearly the same; only its texture is more or less compressed by the vessels, whilst on the contrary the greater or less size of the lungs, which is very apparent, always indicates its state of fulness or vacuity. It is probable even that it is this difference which has made all physicians neglect the infinitely various states of engorgement in which the liver may be found at death, whilst they have had a particular regard to the varieties of the lungs.

The veins of the kidneys, further from the heart, are less exposed than those of the liver to the reflux that takes place in the last moments in which the black blood is obstructed in the lungs. Yet it however takes place, and we see very great varieties in the quantity of blood in the great renal vessels, a quantity independent of that which is constantly found in the organ, and which, as I have said, is very considerable. Now the size of the kidney hardly corresponds to these varieties, because its extensibility is almost nothing.

As to the glands situated at the two extremities, as on the one hand the testicles, and on the other the salivary glands, we hardly observe in them the sanguineous stagnation, because the reflux is not sufficiently evident. We cannot then, in this way, judge but by analogy of their extensibility and contractility.

Yet the engorgements of the testicles, consequent upon gonorrhœa, and the various swellings of the parotid glands prove that these properties exist to a certain extent. Are the liver, the kidneys and other internal glands subject to those acute swellings that are often seen in the sub-cutaneous ones? It is very probable; perhaps even physicians have not paid sufficient regard to the accessory symptoms which may arise for a moment from the pressure of these swelled organs on the neighbouring parts. Besides, this swelling and the contraction that follows it, may take place especially in the cellular texture of the gland, and consequently suppose less extensibility of the glandular texture than they at first seem to.

II. _Vital Properties. Properties of Animal Life._

The animal contractility is evidently nothing in the glandular texture. Does the sensibility of the same kind exist in it? The following facts are connected with this. 1st. A compression of the parotid is to a certain degree painful. I have even been obliged, in a particular case, to give up the method of compression that Desault had advised for a salivary fistula, on account of the pain the patient experienced; but the numerous nerves which traverse this gland may be the cause of these pains. 2d. We know that the instant the lithotome cuts the prostate, or the stone and forceps pass over it, the patient suffers very much. 3d. Stones lodged in the kidneys occasion horrible pains. 4th. Any considerable pressure of the testicle is very painful.

On the other hand we can cut the texture of the liver and the animal will give no signs of pain. Haller, after many experiments, ranked the glands among the insensible parts. What is to be concluded from this? That the animal sensibility, modified in a thousand ways, appears to exist in many organs in which certain agents cannot put it in action, and in which others develop it remarkably. We know that the various morbid alterations render it very evident in the glands. The inflammatory pain of these organs has even a peculiar character; it is obtuse and dull in the greatest number of cases. There is never experienced in them the acute sensation which characterises cellular inflammation, or the sharp and biting pain of which the skin is so often the seat.

_Properties of Organic Life._

Of the properties of organic life, the sensible contractility is wanting in the glandular system. But the two other properties are developed in it to the highest degree. They are in constant activity; secretion, excretion and nutrition keep them in incessant action there. It is by its organic sensibility that the gland distinguishes, in the mass of blood, the materials which are proper for its secretion. It is by its insensible contractility, or its tonic forces, that it contracts to throw out those which are foreign to this secretion. The first is on a small scale in each gland, what the animal sensibility of the tongue and the nostrils is on a large one, which allows only aliments suitable for the stomach to be introduced into its cavity; the other does insensibly, what is effected in so evident a manner by the glottis, when it rises up convulsively against a foreign body that attempts to enter it. The blood contains the materials of all the secretions, of the nutrition of all the organs, and of all the exhalations. Each gland draws from this common reservoir what is necessary to its secretion, as each organ does what is proper for its nutrition, and as each serous surface does what is suitable for its exhalation. Now it is by its organic sensibility that each living part of the body distinguishes what its functions require.

When the fluids enter the small vessels of the gland, this sensibility is the sentinel that gives notice of it, and the insensible contractility is the agent which opens or closes the gates of the organ, according to the principles that are presented. This comparison, if I may be allowed the use of it, gives an idea of what then takes place. Every glandular action turns then especially upon these two properties, and as this action is almost permanent, they are then constantly in exercise.

From this it is evident, that all the glandular diseases ought to suppose a derangement in these properties; for, as we have often seen, they are the predominant properties of an organ, those, the exercise of which constitutes its peculiar life, which especially determine its diseases, by their alteration. This is in fact what observation shows us. Here we see these properties increased or diminished, sometimes produce an increase of secretion, as in diabetes, mercurial salivation, immoderate flow of bile, &c.; sometimes a diminution, a suspension even of this function, as in acute diseases in which all the ducts are closed as it were in a moment, as in the suppression of urine, dryness of the mouth, &c. It is the alteration in the nature of the glandular sensibility that puts it in relation with fluids foreign to the glands in a natural state; hence the innumerable varieties of the secreted fluids especially in diseases. I have spoken of these varieties as it regards the mucous fluids. The liver and the kidneys particularly do not experience less numerous ones. The taste, the colour, the consistence and odour of cystic bile appear in a thousand different states in dead bodies. Who is ignorant of the innumerable alterations of which the urine is susceptible? The saliva is less variable; but in diseases how different is it from its natural state. It is sufficient to have noticed for some time the various evacuations in diseases, to see of how many modifications they are capable. Nothing less resembles the urine and bile, than the fluids sometimes thrown out by the bladder and the liver; whence do these varieties arise? From this, that the variable organic sensibility places the organ in relation with substances to which it was foreign in a natural state; and from this, that the insensible contractility allows substances to enter the organ which it before excluded. The same gland without changing its texture, by a modification only of its vital forces, can then be a source of an infinite variety of different fluids; I believe even that the kidney, by taking a sensibility analogous to that of the liver, may secrete bile. Why may it not secrete it, if it can secrete other fluids so different from its own?

In health, each gland has a mode of sensibility nearly uniform, a mode which changes but little; thus each secreted fluid has an appearance, a consistence and a nature always nearly the same. But in diseases, a thousand causes change this mode at every instant. An hysterical paroxysm strikes the kidneys; in an instant they repulse all the principles that colour the urine, and this comes out limpid; the paroxysm passes off, the organ resumes its ordinary sensibility, and the urine returns to its usual state. The influence of the epileptic paroxysm extends to the sensibility of the salivary glands; in a moment, a thick, copious and frothy saliva, wholly different from the natural, comes from the mouth; after the paroxysm, the sympathetic storm is calmed in the gland, and the saliva returns to its ordinary state. If I may be allowed the comparison, the glands are in diseases like the atmosphere in the equinoxes. At these periods, the winds which succeed each other and incessantly change, often make rain, hail and snow succeed each other in a very short time; so the forces of the glandular life, constantly variable in diseases, make the different products of secretion vary with rapidity.

It is not only to secretion that the various alterations of the organic sensibility and the insensible contractility of the glands extend; these alterations when long continued, have an influence also upon their nutrition; they disturb the course of it; hence the changes of texture, the tumours of different kinds, the organic diseases, &c. that are so frequent in the glandular system, a system which presents the greatest field for morbid anatomy. The great number of organic diseases which it exhibits, in our dissecting rooms, compared with most of the other systems, is very striking. The glandular, the cutaneous, the mucous, the serous, the cellular systems, &c. hold the first rank in this respect. Observe also that it is in them that the organic sensibility and the insensible contractility are raised to the highest degree, because they are the only ones in which these properties are brought into action not only by nutrition, but also by various other functions that are going on in the insensible capillary system, viz. by exhalation, absorption and secretion.

_Sympathies._

Few systems are more frequently the seat of sympathies than this. In examining them I shall adopt the same order as in the preceding system.

_Passive Sympathies._

The glandular texture is affected with extreme ease by all the others. This constitutes its passive sympathies. They take place, 1st, in a natural state; 2d, in diseases.