668 URINE. 



Ms collaborators. 1 The distribution is not the same in all animals and 

 the reports regarding it are conflicting. SCHITTENHELM indeed claims 

 that it has not been proven that guanase and adenase are two different 

 enzymes. Still we have other grounds for the non-identity of the two 

 amidases. 



In birds the conditions are different, v. MACH 2 has shown that in 

 the bird family a part of the uric acid may be formed from the purine 

 bodies. The chief quantity of uric acid, however, is undoubtedly formed 

 in birds by synthesis. 



The formation of uric acid in birds is increased by the admin- 

 istration of ammonium salts (v. SCHRODER), and urea acts in a 

 similar manner (MEYER and JAFFE). MINKOWSKI observed, in geese 

 with extirpated livers, a very significant decrease in the elimination of 

 uric acid, while the elimination of ammonia was increased to a correspond- 

 ing degree. This indicates a participation of ammonia in the formation 

 of uric acid in the organism of birds ; and as MINKOWSKI has also found, 

 after the extirpation of the liver, that considerable amounts of lactic 

 acid occur in the urine, it is probable that the uric acid in birds is pro- 

 duced in the liver by synthesis, perhaps from lactic acid and ammonia; 

 although, as SALASKIN and ZALESKI and LANG have shown, after the 

 extirpation of the liver, an increase in the formation of lactic acid pri- 

 marily occurs, and this causes an increase in the elimination of ammonia 

 (neutralization ammonia). The direct proof for the uric-acid formation 

 from ammonia and lactic acid in the liver of birds has been given by 

 KOWALEWSKI and SALASKIN 3 by means of blood-transfusion experiments 

 on geese with extirpated livers. They observed a relatively abundant 

 formation of uric acid after the addition of ammonium lactate and a 

 still greater formation after arginine. They not only consider ammonium 

 lactate but also amino-acids as substances from which the uric acid can 

 be produced in the liver by synthesis. That these, for example, leucine, 

 glycocoll, and aspartic acid, increase the elimination of uric acid in 

 birds was first shown by v. KNiERiEM. 4 



The possibility of a formation of uric acid from lactic acid has been 

 shown in another manner by WiENER, 5 namely, by feeding birds with 

 urea and lactic acid and different non-nitrogenous substances, oxy-, 



1 See footnote 4, p. 667. See also Mendel and Mitchell, Amer. Journ. of Physiol., 20. 



2 Arch, f . exp. Path. u. Pharm., 24. 



3 v. Schroder, Zeitschr. f. physiol. Chem., 2; Meyer and Jaffe, Ber. d. d. Chem. 

 Gesellsch,, 10; Minkowski, Arch. f. exp. Path. u. Pharm., 21 and 31; Salaskin and 

 Zaleski, Zeitschr. f. physiol. Chem., 29; Lang, ibid., 32; Kowalewski and Salaskin, 

 ibid., 33. 



4 Zeitschr. f . Biologic, 13. 



5 Hofmeister's Beitriige, 2. See also Arch. f. exp. Path. u. Pharm., 42, and Ergeb- 

 nisse d. Physiol., 1, Abt. 1, 1902. 



