76 THE AMINO ACIDS 



in which amino acids are taken up by the tissues and 

 held by them is still undetermined. 



In a later communication the same investigators have 

 attempted to determine the fate of amino acids after 

 absorption by the tissues and selected the changes 

 occurring in the liver. Amino acids absorbed by the 

 liver rapidly disappear. In explanation of this obser- 

 vation several possibilities exist: 1. The amino acids 

 may be excreted through the bile. This view, however, 

 is not probable since the quantities of amino acids in 

 the bile and urine were entirely too small to account 

 for the amount that disappeared from the liver. 2. A 

 second possibility is that the amino acids are trans- 

 ferred to other tissues. This hypothesis is also highly 

 improbable since none of the other large organs show 

 a greater avidity for amino acids, yet three or four 

 hours after injection of amino acids other organs 

 usually contain more amino acids than the liver. 3. 

 The absorbed amino acids are synthesized into body 

 protein in the liver. The possibility cannot be defi- 

 nitely decided at present. 4. The amino acids are 

 deaminated with formation of urea or ammonia. In 

 all probability a portion of the amino acids which 

 disappears from the liver reappears in the urine as 

 urea. 



The disappearance of amino acids from the liver is 

 more rapid and complete than is true for other tissues 

 like the kidney, intestine, pancreas, and spleen. From 

 the muscles the amino acids disappear very slowly. 

 As a summary of the whole question one may quote the 



