282 



ABSORPTION AND SANGUIFICATION. 





both sets of tubes. The epithelium, which lines the absorbent vessel, 

 undergoes a marked change where the vessel enters the gland, and be- 

 comes more .like that of the proper glandular follicles in its character. 

 Instead of being flat and scale-like, and forming a single layer in' close 

 apposition with the basement-membrane, as it does in the lacteal tubes 

 before they enter the gland and after they have emerged from it, we 

 find it composed, within the gland, of numerous layers of spherical nu- 

 cleated cells (Figs. 84 and 85) ; of which the superficial ones are easily 

 detached, and appear to be identical with the cells that are found float- 

 ing in the chyle. The purpose of the cells will be presently inquired 

 into. 



Fig. 84. 



Fig. 85. 



Diagram of an Absorbent Gland, showing the 

 intra-glandular network, and the transition from 

 the scale-like epithelia of the extra glandular ab- 

 sorbents, to the nucleated cells of the intra-glan- 

 dular. 



Portion of intra-glandular Absorbent, showing 

 along the lower edge the thickness of the germi- 

 nal membrane, and upon it, the thick layer of 

 glandular epithelial cells. 



497. After emerging from the mesenteric glands, the lacteal trunks 

 converge, with occasional union, until they discharge their contents into 

 the receptaculum chyli, which is situated at the front of the body of the 

 second lumbar vertebra. Into the same cavity are poured the contents 

 of a part of the other division of the Absorbent system ; which is dis- 

 tributed through the body in general, and which, from the transparency 

 of the fluid or lymph it contains, is termed the lymphatic system. From 

 the receptaculum chyli, arises the thoracic duct; which pass upwards in 

 front of the spine, receiving other lymphatic trunks in its course, to 

 terminate at the junction of the left subclavian and jugular veins ; where 

 it delivers its contents into the sanguiferous system (Fig. 86). A smaller 

 duct receives some of the lymphatics of the right side, and there termi- 

 nates at a corresponding part of the venous system ; but it does not 

 receive any of the contents of the lacteals. 



498. The Lymphatic system is evidently allied very closely to the 

 lacteal, in its general purposes ; and makes its first appearance in the 

 same class of animals, namely, in fishes. The vessels of which it is 

 composed are distributed through most of the softer tissues of the body, 

 and are particularly abundant in the skin. They have never been found 

 to commence by closed or open extremities ; but seem to form a net- 

 work, from which the trunks arise. In their course they pass through 

 glandulae, disposed in different parts of the body, which exactly re- 

 semble in structure those which are found upon the lacteals in the 

 mesentery. And they at last terminate, as already shown, in the same 

 general receptacle with the lacteals. Hence it cannot be reasonably 

 doubted that the fluid which they absorb from the various tissues of the 

 body, is destined to become again subservient to nutrition ; being poured 

 back into the current of the blodd, along with the new materials, which 



