FORMATION OF URIC ACID. 669 



keto-, and dibasic acids of the aliphatic series. The dibasic acids, with a 

 chain of 3 carbon atoms or their ureides, showed themselves most active 

 as uric-acid formers, and WIENER is therefore of the opinion that the 

 active substances must first be converted into dibasic acids. By the 

 attachment of a urea residue the corresponding ureide is produced, 

 according to WIENER, and from this the uric acid is derived by the 

 attachment of a second urea residue. 



Among the substances tested, only tartronic acid and its ureide, diaiuric acid, 

 have shown themselves active in the experiments with the isolated organs, and 

 WIENER therefore also considers that the other acids must be first converted into 

 tartronic acid by oxidation or reduction. From lactic acid, CH 3 .CH(OH).COOH, 

 we first obtain tartronic acid, COOH.CH(OH).COOH, which by the attachment 



yNH OX 



of a urea residue forms diaiuric acid. CO< >CHOH, and from this, by 



\NH CO/ 

 the attachment of a second urea residue, uric acid is formed. 



In opposition to the above-mentioned observations and opinions we must remark 

 that recently FRIEDMANN and H. MANDEL/ by transfusion experiments with 

 geese livers, have come to other conclusions. They found an increase in the uric 

 acid content in the transfused blood without adding any substance, but found no 

 increase in the quantity of uric acid when the transfused blood was treated with 

 urea alone or with urea and sodium lactate or malonate. Further research 

 must explain this contradiction. 



We cannot give any positive answer as to the question whether 

 uric acid is formed by synthesis in man and other mammalia. 

 WIENER has reported experiments which seem to indicate a synthetic 

 uric-acid formation in the isolated mammalian liver, and he has also 

 obtained an increase in the uric-acid elimination, although only a slight 

 one, after feeding lactic acid and diaiuric acid to man. In opposition 

 to these experiments PFEiFFER 2 could find no increase in the elimina- 

 tion of uric acid after feeding malonamide and tartronamide to monkeys 

 as well as tartronic acid and pseudouric acid to monkeys or human 

 beings, and he finds that a synthesis of uric acid in mammalia and man 

 is very doubtful. According to BURIAN S we have for the present no 

 proof of a synthetical formation of uric acid in the mammalian liver. 

 Diaiuric acid and tartronic acid, according to him, do not cause any 

 marked uric-acid formation with extracts of the ox-liver in the absence 

 of purine bases; on the contrary they accelerate the enzymotic oxida- 

 tion of purine bases and hence, according to BURIAN, this explains, per- 

 haps, the increase in uric-acid elimination. 



The liver seems to be the organ in birds where the synthetical forma- 

 tion of uric acid occurs, and the fact that it was possible for MINKOWSKI 4 



1 Arch. f. exp. Path. u. Pharm., 1908; Suppl. Schmiedeberg's Festschrift. 



2 Hofmeister's Beitrage, 10. 



3 Zeitschr. f. physiol. Chem., 43. 



4 I.e. 



