424 HANDBOOK OF PHYSIOLOGY. 



in the vessels of the part from which the lymph is exuded. Thus it ap- 

 pears that the coagulability of the lymph, although always less than, is 

 directly proportionate to that of the blood; and that when fluids are in- 

 jected into the blood-vessels in sufficient quantity to distend them, the 

 injected substance may be almost directly afterward found in the 

 lymphatics. 



Some other matters than those originally contained in the exuded 

 liquor sanguinis may, however, find their way with it into the lymphatic 

 vessels. Parts which having entered into the composition of a tissue, 

 and, having fulfilled their purpose, require to be removed, may not be 

 altogether excrementitious, but may admit of being reorganized and 

 adapted again for nutrition; and these may be absorbed by the lym- 



Fig. 286. Mucous membrane of frog's intestine during fat absorption, ep, epithelium; str. striated 

 border; C, lymph corpuscles ; I, lacteal. (E. A. Schafer.) 



phatics, and elaborated with the other contents of the lymph in passing 

 through the glands. 



The Blood- Vessels. In the absorption by the lymphatic or lacteal 

 vessels just described there appears something like the exercise of choice 

 in the materials admitted into them. This is not the case with the 

 blood-vessels; it appears that every substance, whether gaseous, liquid, 

 or a soluble, may be absorbed by the blood-vessels, provided it is capable 

 of permeating their walls, and of mixing with the blood. 



Where Absorption May Take Place. 



In the Alimentary Canal. The greatest activity of absorption occurs 

 in the alimentary canal. In it the materials of the duly digested food 

 find their way by means of this process on the one hand into the blood- 

 vessels of the portal circulation, and on the other into the lacteal vessels 

 which are, as we have seen, the commencements of the lymphatic vessels 

 of the intestines. 



In the Stomach. Eecent experiments have shown that though ab- 

 sorption does take place in the stomach, it is not as active as was for- 

 merly supposed, even in the case of water. Von Mering has found 

 that water begins to pass from the stomach into the intestine almost 



