LACTIC ACID IN URIC ACID SYNTHESIS 155 



The skeletal plan of the uric acid molecule may be repre- 

 sented as consisting of two fractions of urea fixed to a chain 

 of three atoms of carbon : 



C NH CO 



/wn.2 ^xi 2 , 



C N20 * CO C 



Our ideas in reference to the urea rests required in the 

 synthesis of uric acid are fairly clear. According to the 

 investigations of Knieriem, Jaffe and Hans H. Meyer, as well 

 as those of Schroder, there can be no question as to the abil- 

 ity of the liver in birds to construct uric acid from ammonia 

 salts, aminoacids, as well as from urea. The hypothesis that 

 in the avian body, just as in mammals, the protein nitrogen is 

 first broken down into urea, and subsequently as a secondary 

 process is synthesized into a complex of two urea rests and 

 a group of three carbon atoms is an entirely satisfying 

 one. 



What is the significance of this triple group of carbon 

 atoms? Minkowski's well-known experiment, in which he 

 noted the appearance of lactic acid and ammonia in the urine 

 of geese from which the liver had been extirpated, has forced 

 lactic acid for the past nearly twenty years prominently into 

 consideration, and has apparently harmonized the general 

 subject. It has been proved that the appearance of lactic acid 

 is due to the loss of the hepatic function ; as ligation of all of 

 the hepatic vessels produces the same effect, but if even a 

 single branch of the hepatic artery be open there is no forma- 

 tion of lactic acid. To prove that the failure of uric acid for- 

 mation is actually due to the exclusion of the liver and is not 

 in some way a secondary result of accumulation of lactic acid 

 in the body, requiring considerable ammonia for neutraliza- 

 tion and thus interfering with synthesis of uric acid, we may 

 recall the fact that (as Sigmund Lang was able to show in 

 Hofmeister's laboratory) introduction of alkali into geese 

 with excluded livers is not followed by any increase in the 



