ABSORPTION. 



147 



in the wall of the intestine. Here it is again the epithelium of the 

 intestine that changes the peptone into serum-albumin and serum- 

 globulin. The digestion of proteid is chiefly accomplished by the 

 trypsin; removal of the pancreas confirms this. In a mixed diet of 

 milk, meat, eggs, butter, and bread, about 90 per cent, is absorbed. 



'ep 8tr 



Fig. 39. A, Section of Villus of Rat killed during Fat Absorp- 

 tion. ( SCHAFEB.) (From Mill's "Animal Physiology," copyright, 1889, 

 by D. Appleton and Company.) 



ep, Epithelium, sir, Striated border, c, Lymph-cells, c', Lymph-cells in 

 epithelium. I, Central lacteal containing disintegrating corpuscles. 



B, Mucous Membrane of Frog's Intestine during Fat absorption. 

 ( SCHAFEB. ) 



ep, Epithelium, sir, Striated border. C, Lymph-corpuscles. I, Lacteal. 



Absorption of Fats. 



Whilst the stomach has a ferment which can split up a small 

 part of emulsionized fat into fatty acid and glycerin, in steapsin 



tsve have a ferment which splits up the fats into fatty acids and gly- 

 cerin. The gall intensifies this action of steapsin. Besides, we have 

 sodium-soap from the presence of that alkali in the gall, pancreatic, 

 ind intestinal juice. Now, the soap and fatty acids are absorbed by 

 the epithelium of the villus. It has been shown that the fatty acids 



