The size of the lymphatic glands, is variable, from the tenth of a line in diameter, to the size of a hazle-nut, and even larger. They are oftentimes so small that we can with difficulty discover them, and they cannot sometimes be seen until disease has developed them. Their increase in size is an ordinary effect of scrophulous affections, which often show us lymphatic glands in places where we did not know that they existed, especially on certain parts of the face and neck. We cannot say then that the swellings of the cellular texture deceive us; for the comparison of these bodies, which are thus made evident by the disease, and which no doubt pre-existed, with the known lymphatic glands, and which are then found equally swelled, proves their perfect identity. All exhibit either the same fatty and white substance, or the same caseous pus, according to the period of the disease.
In general these glands are much developed in childhood, diminish in the adult, and almost disappear in old age. They are, it appears to me, a little more evident in women than in men, in the phlegmatic temperaments than in the sanguine. Of all the different enlargements of which they are capable in different places, the tabes mesenterica gives them the greatest size.
Their form, sometimes oval, sometimes more or less elongated, always tending to a round one, which is generally that to which all the organs of animals, and even all those of organized bodies are disposed; whilst those of inorganic bodies assume those of cubes, prisms, &c.
The lymphatic glands, sometimes insulated as in the extremities of the limbs, collect in greater number as they approach their common trunks. The axilla and the groin contain many of them, as I have already said; but in the abdomen, they are united in a group, and are so close to each other in the mesentery, that they have appeared to Azelli to form in this place, not an union of organs, but a single one, which he has taken for a second pancreas, and to which he has given his name.
II. Organization.
The colour of these glands, reddish in childhood, grey in the adult, becomes of a yellowish tinge in old age, and has that subsidence and flaccidity which then characterize almost all the organs. This colour varies also according to the regions; thus the bronchial glands have a black appearance, inherent in part in their structure, but owing probably also to the fluid that they contain, as the appearance of this fluid proves, when it is pressed out of a divided gland. This colour does not depend on its proximity to the lungs and on their colour, though we know, they have many black spots upon them; the proof of this is, that I have already very often found the lumbar, mesenteric glands, &c. also black. Yet there is no part in which this colour would be more common than around the lungs. Cruikshank, in order to prove the passage of the lymphatics through the glands, says that he has found those in the neighbourhood of the liver yellow in jaundice, in which it is very probable that there is absorption of bile. But this remark is unimportant, since all the parts of the body, without exception, exhibit, in this affection, this colour, which is only a little more evident in the cellular parts.
We cannot deny however but that these glands often take a colour similar to that of the fluid which fills the absorbents, either in a natural state, or in injections, on account of the great number of vascular divisions that penetrate them internally. During digestion, at the moment the lacteals are transmitting chyle, the mesenteric vessels become almost as white as this fluid, and soon lose this colour when the transmission is finished. By filling the absorbent system with mercury, the same phenomenon is observed.
Common Parts.
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.