134 NUTRITIONAL PHYSIOLOGY 



digestive cleavage may be continued during the passage 

 through the wall, or a recombining of the products of diges- 

 tion may be accomplished. The first action is thought to 

 occur to some extent when the peptones formed in the 

 cleavage of proteins are moving toward the blood. It will 

 be recalled that the enzyme erepsin, having the power to 

 decompose peptones still farther, is obtainable from 

 these cells, and it is quite possible that its action is intra- 

 cellular. 



The opposite property, that of synthesizing, is illustrated 

 by the behavior of the products of fat digestion. We have 

 seen that the pancreatic enzyme hydrolyzes fats, with the 

 formation of fatty acids and glycerin as the first result of 

 the cleavage, and that the fatty acid may be changed to 

 soaps, though we do not know how extensively they under- 

 go this second change. It follows that it is these bodies 

 which disappear from the intestine, but they are not to be 

 found at all freely in the contents of the lymphatics. 

 In their place we have neutral fat evidently reconstructed 

 during the transfer. Microscopic study of the cells 

 through which the material has been passing shows that 

 the border adjoining the cavity of the intestine is without 

 fat droplets, but that these occur deeper down, increasing 

 in size toward the other border. The appearance strongly 

 indicates that some compounds other than neutral fats 

 entered the cells and underwent a transformation while 

 progressing through the protoplasm. 





