PROTEIN AND CIRCULATION 69 



one to the belief that this substance is of the nature 

 of proteose rather than that of a complete protein so 

 that plastein formation affords little or no evidence for 

 the support of the existence of protein synthesis. 



The Synthetic Action of Pepsin and Trypsin 



It has been demonstrated by A. E. Taylor that by 

 the long continued action of trypsin of the clam liver 

 upon concentrated protamine digestion products a 

 reformation of protamine takes place. The quantity 

 reformed is very small in comparison with the original 

 amount of protamine digestion products. In a similar 

 manner Robertson has found the synthesis of a para- 

 nuclein by the action of pepsin upon concentrated 

 casein digestion products. These results lead to the 

 suggestion that trypsin and pepsin may possess a two- 

 fold action, a disintegrative influence and a synthetic 

 action in accord with the idea of the reversibility of 

 enzymes. If the synthetic action in the intestine is as 

 slow as that shown in the experiments just cited little 

 value can be assigned to them as aids in the regenera- 

 tion of protein in the body for the influence could be 

 observed only after the influence had continued for 

 several months. 



The evidence for the synthesis of protein in the 

 intestinal wall is all of an indirect nature. If the 

 adherents of that theory could demonstrate an increase 

 of protein in the blood after an ingestion of protein 



