PROTEIN AND CIRCULATION 65 



was carried out there. He held that such a hypothesis 

 was contrary to all existent knowledge of physiological 

 assimilation." 



One may query to what extent does immediate 

 resynthesis take place ? Are all the digestion products 

 transformed into coagulable protein or are some se- 

 lected and others rejected in part? The questions 

 cannot be answered by the supporters of Abder- 

 halden's theory. On the other hand, the intestine evi- 

 dently is capable of exerting a marked selective action 

 as to the type and amount of amino acid it shall absorb. 

 The experiments of Abderhalden and his co-workers 

 have indicated this. They fed gliadin to polyfistular 

 animals and observed as the material traversed the 

 gastro-enteric tract that tyrosine disappeared from the 

 intestine whereas glutamic acid steadily increased in 

 amount. 



Freund. The idea of Freund is somewhat similar 

 to the hypothesis advanced by Abderhalden except 

 that he ascribes to the liver an important role in the 

 subsequent breakdown of the protein. The protein 

 digestion products are assumed by Freund to travel 

 the portal circulation in the form of pseudo-globulin. 

 The liver is unable to properly decompose protein 

 unless it has first entered the blood stream by way of 

 the intestine. This hypothesis carries with it the sug- 

 gestion that the parenteral utilization of protein must 

 be carried out through aid from the intestine, that the 

 protein is excreted from the blood into the intestine, 

 undergoes digestion, the products are absorbed, and 



