THE METABOLISM OF THE PURIN BODIES 425 



from which he argued that synthesis had disappeared. Salaskin 

 has confirmed Minkowski by showing that when lactic acid is per- 

 fused through the liver of a goose uric acid is formed. 1 



Wiener ( 19 ) has carried this subject of uric acid synthesis farther, 

 and has shown that not only lactic acid but a whole series of 

 organic acids and related substances can furnish the carbon chain 

 which links the two urea molecules together. To demonstrate 

 clearly what these substances are, Wiener used geese whose tissues 

 contained an excess of urea. If urea alone be fed to birds in 

 moderate amount it all becomes transformed into uric acid, but if 

 an excess be given (subcutaneously) all is not thus synthesized 

 because all the available store of substance which yields the carbon 

 chain becomes used up so that some is excreted unchanged in the 

 urine. If now, to a goose, thus treated with urea till some over- 

 flows into the urine, lactic acid be given, an immediate increase 

 in uric acid excretion follows, for the lactic acid furnishes the 

 necessary tri-carbon chain for the synthesis. Experimenting in 

 this way, Wiener has shown that any oxy, ketone, or dibasic acid 

 of the fatty acid series with a chain of three carbon atoms, or any 

 of the higher organic acids or their derivatives 2 which, by their 

 metabolism in the tissues, produce one of these, is capable when 

 given with the food of furnishing the connecting link for the 

 synthesis. 



Working on artificially perfused livers on the other hand, 

 Wiener found that the only one of these bodies mentioned above 

 which caused any marked increase in uric acid formation was a 

 dibasic acid called tartronic. This has the formula : 



/COOH (oxy-malonic acid) 

 CHOH< 



\COOH 



and is the lowest possible dibasic oxy-acid. 



The urea residues attach themselves to this in two stages, 

 the first formed compound of tartronic acid with one urea mole- 



1 There is, however, some truth in Bunge's contention, for Long ( 20 ) has found 

 that if alkali be administered to liverless fowls there follows a diminution in the 

 ammonia excreted. 



2 The only one of these higher acids which Wiener found to cause any 

 marked increase in uric acid was /3-oxy-butyric. Propionic acid, which is pro- 

 duced when most of the higher acids break down in the tissues, does not enter 

 into the synthesis. 



