NITROGENOUS COMPOUNDS 129 



pepsin-hydrochloric acid mixture further subjected 

 to the influence of pancreatin contained only half as 

 much polypeptides, whereas from that formed by acid 

 hydrolysis polypeptides were entirely absent. Later, 

 however, it was shown by Abderhalden and his co- 

 workers that the varying content of polypeptides can- 

 not be the sole reason for the differences observed in 

 the two classes of products in their ability to supply 

 the nitrogenous needs of the body, for a dog was kept 

 alive for thirty-eight days and the only supply of nitro- 

 gen was in a digestion mixture containing only amino 

 acids. Again, a young dog gained weight and retained 

 nitrogen in completely digested meat and a bitch was 

 kept in nitrogenous equilibrium during lactation with 

 meat digested to the amino acid stage. Abderhalden 

 and London were able to maintain a dog with an Eck 

 fistula (the liver shunted out of the portal circulation) 

 on fully digested meat. From this experiment they 

 further concluded that the liver could play a small 

 role only in protein synthesis and used these results 

 as support for their view that protein synthesis occurs 

 during absorption. 



From the work of Henriques, Abderhalden and 

 others it soon became evident that the difference in 

 nutritive value between ferment and acid hydrolysis 

 products could not be ascribed wholly to the presence 

 or absence of polypeptides. Upon closer investiga- 

 tion it developed that the failure of acid hydrolytic 

 products to meet nutritive requirements satisfactorily 

 could be explained by the fact that during acid hydroly- 



