423 



the epithelial cells which line the intestinal tract, and especially those 

 which clothe the surface of the villi. Thence, the fatty particles are 

 passed on into the interior of the lacteal vessels, but how they pass, and 

 what laws govern their passage, are not at present exactly known. The 

 lymph-corpuscles of the villi are however, in some animals, e.g., the rat 

 and frog, important agents in effecting the passage of fat-particles into 

 the lacteals. These cells take up the fat which has passed through the 

 columnar cells and then, by reason of their amaeboid movement, carry 



Fig, 885. Section of the villus of a rat killed during fat absorption, ep, epithelium ; sir, striated 

 border; c, lymph-cells ; c', lymph-cells in the epithelium; 1, central lacteal containing disintegrating 

 lymph-corpuscles. (E. A. Schafer.; 



it in to the lacteal. When arrived there they break up and set free 

 both fat and proteid matter thereby. 



The process of absorption is assisted by the pressure exercised on 

 the contents of the intestines by their contractile walls; and the absorp- 

 tion of fatty particles is also facilitated by the presence of the bile, and 

 the pancreatic and intestinal secretions, which moisten the absorbing 

 surface. 



The Lymphatics. The lymph is diluted liquor sanguinis, which is 

 always exuding from the blood-capillaries into the interstices of the tis- 

 sues in which they lie; and as these interstices form in most parts of 

 the body the beginnings of the lymphatics, the source of the lymph is 

 sufficiently obvious. In connection with this may be mentioned the 

 fact that changes in the character of the lymph correspond very closely 

 with changes in the character of either the whole mass of blood, or of that 



