The absorbents are found in consider able numbers under the akin of the extre mities; and when they arrive at the groin and arrn pit, they pass through little bodies about the SiZe of small &sans, which are called lymphatic glands. The absorbent ves,sels, as they approach the gland, gene rally separate into several Isranches, which terminate in that brxly : and again, about an equal number of absorbents emerge from the gland, conjoin, and form one or more principal' absorbing vessels. The absorbents, which enter the gland, are usually denominated vasa inferentia, and those which go out of it, vasa efferentia. If quicksilver be poured into the former vessels, the gland swells, and a great deal of quicksilver appears to be deposited in it ; and afterwards, if the power ling the injection be continued, it is seen coming out of the gland by the rasa efFer entia. It seems therefore to follow, that the progress of the absorbed fluid is checked a little in these glands, and it is probable, that some change is effectedin its progress throug-h them. This opinion is confirmed by obseming, that these glands abound with blood-vessels, which probably pour some fresh animal juices into those which are contained in the lymphatic vessels The lymphatic glands are found in great numbers in the groin, armpit, and side of the neck, apparently serving like barriers to the absorbents of the bead and extremities, as they- approach to the large veins of the trunk. The absorb ents of the intestines, which contain the chyle, a scarcely animalized fluid, some times pass through three or four sets of glands, before they arrive at the thoracic duct; hence they are called lacteal ves sels primi, secundi, tertii, or quarti gene ris. The place where the lacteals conjoin, and meet with the lymphatics from the lower parts of the body, to form the tho. racic duct, appears in anireals like a re servoir, and has been named the recepta culum chyli. The vessel thus formed,
penetrates the diaphrag-rn, in conjunction with the aorta, and is called the thoracic duct. In this situation it lies close on the back bone, between the vena azygos and the aorta. Towards the neck, it leaves the bone to reach theleft subclavian vein, into which its contents arc poured; the absorbents of the left arm and side of the head having previously joined it. The passage of blood from the Will into the duct is effectually precluded by means of valves The absorbents of the right arm and side of the head form a smaller trunk on the right aide, which opens into the cor responding part of the right subclavian vein.
Thus, all the old materials of the body, which the absorl3ents are continually re moving, all the new matter imbibed frotn the surface, all the redundant lymph taken up from the interstices of the body, and all the chyle occasionally obtained from the bowels, are conveyed into the large veins near the heart. It is, in short, chiefly by this system of vessels, that the blood is augmented in quantity, or alter. ed in quality ; they replenish the body with nutriment, and occasionally taint it with infection.
It is sufficient to inform the reader, that these vessels exist in great numbers in all parts of the body, without entering into any detailed description of their particu lar distribution. We may just observe, that the course efthese vessels, and their entrance into giands,become occasionally demonstrated in disease. When irritated by aro, local mischief, they form red streaks, manifest on the surface of the body and the imitating or poisonous na ture of the matters which they imbibe causes swelling and inflammation of the glands in which this matter is deposited. Thus the glands in the groin swell from the absorption of venereal matter ; those in the axilla become affected in cancer, and in the inoculation for the small pox.