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.