Part 14

The structure of the lymphatic glands, considered in its common parts, is as follows; a very abundant, extensible, loose cellular texture surrounds them, allows them to be moved and easily displaced by the finger when pushed against them. Hence the remarkable mobility of most of these organs, in the first periods of their swelling; in which this texture does not then participate; for it is gradually affected, loses its laxity, and then adhesion succeeds to mobility. Thus in cancer, the glands are first rolling, and afterwards become fixed. In acute inflammations, they are in general fixed, because the neighbouring texture partakes almost always of the disease.

The cellular texture forms besides around the glands a thick membrane which more immediately envelops them, and which deprived of fat and serum, exhibits the nature of the cellular covering of the absorbents. It is this last membrane which, in the ordinary state, gives to the glands an appearance in general smooth and polished; for mercurial injections develop in them some roughness, owing to the prominence of the vessels that run through them in the interior. Some slight depressions are also visible on their surface; they are to these glands, what the furrows on their concave face, are to the liver, the spleen and the lungs; it is through them that the vessels enter. We might think that the arteries were very numerous in the lymphatic glands, if we judged from injections which colour the whole of them, if they are fine and adroitly used; but little reliance should be placed upon this. Simple inspection, in a living animal, which is infinitely more certain, does not discover much blood in these glands. In the fœtus and in childhood, the quantity of this fluid is much more considerable; hence in part the redness that characterizes these organs at this period of life. We are ignorant whether nerves exist in them, and whether any of the numerous branches that the ganglions send in their neighbourhood, especially in the mesentery, are introduced into their texture; I have never traced any of them there.

Peculiar Texture.

The peculiar substance of the lymphatic glands exhibits a pulp very analogous to that of the nervous ganglions. No fibre can be distinguished in them. Soft in the fœtus, withered in the few glands that remain in old age, this substance, is particularly altered, as I shall say, by scrophulous diseases, and by the influence of the affections of the neighbouring organs.

This peculiar texture has a greater or less density. We find it more solid, and resisting better the injection of mercury in the superficial glands than in the deep-seated. They have cells at short distances, especially in childhood; they contain a whitish fluid, which disappears as well as the cells themselves, at an advanced age. This fluid, of a very peculiar nature, can only be compared with those of the thyroid and thymus glands, which, like this, are found as it were extravasated, in the interstices of the organs that separate them, they have no reservoirs, and their use is wholly unknown. There is no doubt that the great quantity of blood that enters the lymphatic glands in childhood, is owing to the superabundance of this fluid. Sometimes in the adult, there is a great quantity of it in the bronchial glands, where it is of a blackish colour. Some physiologists have thought, without anatomical proof, that it is spread out upon the bronchiæ, and that it forms in part the black spittle that is thrown out in the morning. Fourcroy in particular is of this opinion; he attaches importance to the black colour of these glands, which are perhaps, according to him, the reservoir of the carbonaceous matter of the blood. The fact is, they belong to the lymphatic system; that in a great number of subjects they are grey or red; that we do not know that they have an excretory; that their texture is pulpy like that of the analogous glands; and that their size distinguishes them however from all others. I have observed that the acids, the alkalis and stewing, alter but little their black colour and that of the fluid contained in them.

It is in the peculiar texture of the lymphatic glands that the absorbents ramify, after being introduced there in a certain number, and each with numerous ramifications, and afterwards go out by many other branches which also give rise to an infinity of smaller ones. Each gland may in this respect be considered as the centre of two small opposite capillary systems, which anastomose with each other. In the interior of these glands, these branches very tortuous, folded upon themselves in different ways, occupy a great part of the peculiar texture of these organs which many thought in consequence were nothing but an interlacing of the absorbents; an idea that is not proved, since this texture is not yet well known.

I have observed that it is susceptible of less horny hardening than most of the other animal textures. It approximates in this respect that of the true glands; but it differs in this, that instead of continuing to harden by long continued boiling, it soon softens, becomes pulpy, and breaks with great ease under the finger. The acids after having crisped it, dissolve it also more easily than many of the other textures; the sulphuric and muriatic are remarkable for this. Exposed to the action of the alkalis, it loses some of its principles, which weaken these menstrua; but it is never entirely dissolved.

ARTICLE THIRD.

PROPERTIES OF THE ABSORBENT SYSTEM.

We shall consider in the same article the properties of the absorbent vessels and those of their glands.

I. Properties of Texture.

Extensibility of texture exists in the absorbent system. 1st. The thoracic duct is distended in an evident manner by injection, before the rupture of its peculiar membrane takes place. 2d. I have said that the absorbents examined around the serous membranes in a living animal, principally in the liver, often exhibit little bladders or considerable dilatations. Are these dilatations varices? is there an analogous character in this respect, between the absorbents and the veins? I know not; whatever they are, they can be very considerable in a long absorbent vessel. 3d. When we tie the thoracic duct, not only that swells, but the lymphatic vessels of the abdomen also dilate, and this ligature is the most convenient means of observing the lacteals. This extension has undoubtedly limits; carried too far, it would probably produce in a natural state the rupture of the vessels, as happens from injections. We have not yet any data founded upon observation or experiment, respecting this rupture, though some authors have endeavoured to explain by it the formation of most dropsies.

Contractility of texture is evident in the absorbent system. 1st. When the thoracic duct is distended even in a recent dead body, and the fluid is discharged by puncture, it immediately contracts. 2d. All the absorbents contract also as soon as there is no more fluid in their cavity. This phenomenon is remarkable during the absorption of chyle; when that is finished, these vessels evidently disappear by the effect of this contraction. 3d. The absorbent glands, swelled at the moment chyle is passing through them, afterwards lose much of their size by this contractile power.

II. Vital Properties.

We have but few data concerning the animal properties of the absorbents. Sensibility of relation does not appear to exist in them; it is difficult to ascertain this by experiments. When we puncture a lacteal when it is full of chyle, a lymphatic filled with serum on the surface of the liver, or even the thoracic duct, the animal gives no indication of pain. But what inference can be drawn under circumstances, in which the abdomen being opened, the numerous painful sensations would render nothing, comparatively, the slight sensation which the puncture produced, admitting that it existed? No experiment, I believe, has yet been attempted to ascertain if irritation carried to the interior of these vessels produces a sensible effect. Probably the same result would be obtained by fine injections used for this purpose, as has been for the veins, considering the analogy of structure and the continuity of the peculiar membrane of both systems.

There are circumstances however in which the absorbents have a very acute sensibility, viz. when they are inflamed. It is a very frequent phenomenon in diseases, that there is a very evident swelling and redness, along the course of the sub-cutaneous absorbents in the lower extremities, giving considerable pain to the patient, terminating at the inguinal glands, or even extending beyond. In wounds with a poisoned instrument, in the acute pains of a whitlow, &c. a very painful sensation is often felt the whole length of the absorbents of the superior extremities.

The lymphatic glands do not appear to enjoy, in a natural state, animal sensibility, when they are irritated in different ways, which can easily be done. But inflammation may develop it in these glands as in the absorbents, by raising to a high degree their organic sensibility. Thus the pain is very acute, when after a puncture made by an infected instrument, after a sprain, &c. these glands swell. We know the extreme suffering that arises from those in the axilla, when they swell and suppuration succeeds. Shall I speak of the pains experienced from the mesenteric glands when cancerous? Who is ignorant of those which buboes occasion, &c.?

As to animal contractility, it is entirely wanting in the absorbents and their glands.

The organic properties exhibit in the absorbent system, the following arrangement. Sensible contractility has been allowed them by Haller. It is founded upon this, that the lymphatics easily empty themselves of the chyle that passes through them, and upon this also, that by touching them with sulphuric acid, they crisp immediately. But sulphuric acid, like all the concentrated acids and caloric, produces the same effect upon all animal substances, even after death; it is the horny hardening. When the absorbents, particularly the thoracic duct are touched with the point of a scalpel, no contraction follows. If they are capable of contracting upon themselves, it appears that it is when they cease to be distended, and not when they are irritated; and that it is consequently by their contractility of texture. The sensible organic contractility is then at least doubtful in them, if it exists it is very obscure and at most to be compared to that of the dartos muscle.

The organic sensibility and the insensible organic contractility are evidently found in the absorbents. It is by these properties that they perform their functions, that fluids are absorbed by them, that they circulate in their branches, &c. &c. These two properties are remarkable in them in this, that they continue some time after death. A fluid injected when the animal is still warm, is absorbed, either on the serous or mucous surfaces. It is less easy in the cellular texture. We can prolong a little this absorbent power, by supporting the heat artificially by a bath. This has in general less efficacy than I thought for a long time. Various recent experiments have convinced me of this. This arises no doubt from the fact, that it is the vital heat and not an artificial one, which is necessary to the exercise of this function, or rather vital heat and absorption are two effects of a common cause, viz. organic properties. As long as these properties remain in the solids, they retain caloric and absorb. But the moment they are gone, the heat goes and at the same time absorption ceases. It would be useless to expose to caloric, solids that life had entirely abandoned; they would become warm; but they could exhibit no vital phenomenon. In the same way it would be useless to keep up the heat of an animal recently killed, by making an artificial one succeed the natural. It is organic sensibility and insensible contractility, that must be prevented from escaping to prolong absorption. If artificial heat keeps up this function, it is only by first keeping up these properties. We cannot calculate upon absorption when the animal is cold, though Mascagni and many others have said otherwise. I have in vain attempted to keep it in action then; generally I have not observed it above two hours after death. The organic sensibility is in relation with many fluids in the absorbent system, and it is in this that it differs from the other systems, the glandular, for example, which is never in relation but with one particular fluid, and which rejects all the others in a natural state. Water and other mild fluids can easily be absorbed, though very different from the lymph. In the natural state, the thoracic duct alternately admits chyle and lymph.

Character of the Vital Properties.

From what has been said, it is evident that the organic properties perform the principal part in the peculiar life of the absorbent system. These properties are much more conspicuous there than in the venous system; at least they are much more capable of being raised. In fact there are ten inflammations of the absorbents for one of the veins. This disposition to inflame from the least virus that passes through their tubes, from pains, though not severe, that are felt at their extremity, particularly characterizes these vessels. It is rare that there is found in the course of a vein, those swellings, pains and inflammations so frequent in the course of the absorbents. This difference proves a diversity of structure in the peculiar membrane, notwithstanding its continuity with that of the veins. In fact at the period when experiments were made upon the transfusion of medicines into them, authors have not related any case of venous inflammation from the contact of foreign substances upon the membrane of the veins; whilst practice frequently presents us this fact in the absorbents.

The lymphatic glands especially have a great tendency to inflammatory swellings, when deleterious substances that are absorbed come in contact with them. In the first periods these substances confine their effects to the first glands they meet; thus the absorption of the venereal virus hardly extends beyond the glands of the groin; thus the axillaries alone swell when a puncture is made with an infected instrument, &c.; the glands that follow, remain untouched.

Though much disposed to inflame, the lymphatic glands exhibit however more slowness in this affection, than many other animal textures, the cellular and cutaneous, for example. We know that phlegmon and erysipelas go through their periods quicker, than the inflammations of the inguinal, axillary glands, &c. The pain of which these inflamed glands are the seat differs also much from that of these two affections; it is more dull, obscure, &c. The pus is more slow in forming; it resembles considerably cellular pus; it differs much from that of erysipelas. There are few textures in the economy that are more disposed than this to hardening after inflammation. For one single time that the skin become scirrhous after erysipelas, the lymphatic glands become so twenty. This is truly one of their distinctive characters.

The absorbents often exhibit to a certain degree, like their glands, a character of slowness in the phenomena over which their organic properties preside. For example, when concerned in a wound, they contract, crisp up and close more slowly than the sanguineous capillaries, that are then also concerned; hence the flow of serum that continues for some minutes after that of blood has ceased. This phenomenon is constant in small wounds. If the absorbents and the capillaries had the same degree of insensible contractility, it certainly would not take place.

Here then are new proofs of the principles of which we have every instant occasion to present the consequences in this work; viz. that the vitality peculiar to each system, the particular degree of vital forces that characterize them, imprint upon all its affections a peculiar tinge and aspect, if I may so express myself, unknown to all the other systems.

Differences of the Vital Properties in the Absorbent Vessels and their Glands.

Though we have considered at the same time the vital properties in the glands and in the absorbents, though anatomy shows the first to be an assemblage of folds and vascular windings, yet it cannot be denied that they have a peculiar kind of vitality, by which they are distinguished from the absorbents that come to them. It is this peculiar kind that exposes them to certain diseases of which the absorbents are not the seat, at least not in so evident a manner. The scrophulous virus seems more especially to attack them. They are particularly affected in tabes mesenterica, strumous diseases, &c. In the innumerable swellings of which they are the seat in consequence of organic diseases, the absorbents do not appear at the same time altered in their texture. It seems even that in a very great number of cases, the numerous folds that these vessels form in the glands, do not partake of their organic injury; they, in fact, transmit the lymph as usual. Nothing is more common than to see abdominal and thoracic enlargements of these glands in children, without producing serous effusions, even at the most advanced periods. In opening the bodies of small subjects, I have often been astonished at this phenomenon. The lymphatic vessels are not even more dilated, at least we do not find them easier in children affected with tabes mesenterica, than in others. We can hardly ever discover them at this age to inject.