THE PROTEINS AND THEIR METABOLISM 103 



Schematic Illustration of the Digestion of Proteins in the Gastro- 

 intestinal Canal 



Dipeptids. 



Amino-acids. 



Amino-acids. 

 Prolin. 

 Phenylalanin, etc. 



Erepsin. diges- 

 tion. 



The above shows in a general way the scheme of protein digestion, and 

 is reproduced to show that the protein molecule does not break up in an 

 explosive manner, by which the whole molecule disintegrates, but that it 

 takes place in stages, and that a large number of intermediary bodies are 

 possible in the course of protein digestion. 



The Absorption of Products of Protein Digestion 

 from the Gastro-Intestinal Canal 



From what was said above it is evident that digestion in the stomach 

 does not proceed to the point where products are formed that are ab- 

 sorbable. Hence very little or no absorption of protein-digestion-products 

 takes place normally (London-Abderhalden). If amino acids or peptones 

 are introduced into the stomach they are absorbed with considerable rapid- 

 ity (Folin and Lyman, 1912 (a,)). 



The greatest bulk of the absorption takes place from the intestines, 

 from which the lower peptids and amino acids are absorbed with great 

 lapidity, and carried by the blood stream to the various organs of the 

 body. 



