INFLUENCE OF THE FOOD ON THE TISSUES 63 



periments might have been formed from other amino acids, such as 

 leucine and alanine, which had combined with the benzoic acid, the 

 resulting product having been then converted by a process of oxidation 

 into hippuric acid. He carried out a series of experiments to test this 

 hypothesis, but did not obtain positive results. He tested some ten 

 preparations, but in none did he get conversion into hippuric acid. 



Abderhalden and Funk (33) also investigated this question, and 

 came to the conclusion that the only amino acid of which definite 

 proof of formation or synthesis in vitro can be obtained is glycine. 

 They also utilized the evidence obtained by feeding with caseinogen in 

 which there is no glycine ; the animal was rapidly got into a state of 

 nitrogenous equilibrium. It must therefore be concluded that syn- 

 thesis of glycine can be readily brought about with little or no strain 

 on the protein anabolic processes. They were unable to confirm an 

 observation of Henriques (186) on the synthesis of lysine in the animal 

 body (rats). Henriques stated that although zein, which lacked glycine, 

 lysine and tryptophane, could not maintain life when given in the food 

 as the sole source of nitrogen, yet under the same conditions this 

 could be successfully accomplished by gliadin, which lacked lysine. 

 The deduction was that either lysine was not required or that it could 

 be synthetized from some of the other amino acids present. Abder- 

 halden and Funk repeated this experiment on a dog and found that 

 nitrogenous equilibrium could be obtained, but their analyses showed 

 the presence of a small amount of lysine in gliadin. 



Wiechowski (420) also found that there could be a greater output 

 of glycine after dosing a rabbit with benzoic acid than could be ac- 

 counted for by the amount of glycine present in the tissue proteins. 

 He came to the extraordinary conclusion that in the rabbit glycine 

 was the principal source of the urea, and that all the other amino acids 

 were converted into glycine before their final destruction in the body. 

 Such a conception does not seem necessary to explain the facts already 

 known as regards the fate of the amino acids in the body. 



On the other hand Brugsch (76) stated that the amount of glycine 

 which was excreted after giving benzoic acid was equal in amount to 

 that which existed as such in the tissues and which could be ob- 

 tained by hydrolysis in vitro. Tsuchiga (400) obtained results which 

 varied considerably and no definite conclusion could be reached. He 

 maintained that according to the dose and the method of administra- 

 tion of the benzoic acid, the amount of glycine excreted as hippuric 

 acid fluctuated greatly. 



The evidence then is in favour of a synthesis of glycine taking 



