PROTEIN AND CIRCULATION 59 



2. The proteins of the food are hydrolyzed and the 

 products are absorbed and carried to the tissues. 



3. The digestion products are synthesized into 

 serum protein by the intestinal wall during the act of 

 absorption, and the serum protein serves as pabulum 

 for the tissues. 



4. Deamination of the digestion products occurs 

 previous to their entrance into the circulation. Since 

 it is impossible to accept the hypothesis that unchanged 

 protein is the form in which ingested protein is usually 

 absorbed the next natural inference is that the pro- 

 teoses and peptones are absorbed directly into the blood 

 and conveyed to the tissues. In attempting to deter- 

 mine the correctness of this hypothesis the query has 

 arisen 



ARE PROTEOSES AND PEPTONES PRESENT IN THE 

 BLOOD? 



In spite of the discovery of erepsin by Cohnheim 

 and the consequent improbability of proteoses and 

 peptone representing the usual form of final digestion 

 products, some modern investigators have clung to the 

 idea that it is in the form of proteoses and peptones 

 that protein is absorbed. This view is based upon a 

 number of investigations from which the assertion has 

 been made that proteoses and peptones are present in 

 the blood stream. The work of Neumeister led to the 

 conclusion that proteoses and peptones are not found 

 in the blood and it was not until 1903 through the 



