390 CHEMISTRY OF THE LEUCOMAINS. 



found in the semen of bull the four bases, adenin, guanin, xanthin, 

 and hypoxanthin. In the nucleinio acid from bull's testicles 6.039 

 per cent, of xanthin was found ; guanin was absent. The amount 

 of hypoxanthin was also large, 1.96 per cent, against 0.736 per 

 cent, of adenin. Drechsel isolated xanthin and cystin from the 

 liver of the horse. Unger and Phipson have extracted it from 

 guano. 



From fresh adrenals Okerblom obtained less xanthin than when 

 these were digested for two days at 37° in the presence of chloro- 

 form. In the latter case chiefly xanthin, some 1-methyl xanthin 

 and hypoxanthin and traces of epiguanin and adenin were found. On 

 the other hand in auto-digested pancreas and yeast Kutscher found 

 only traces of xanthin and hypoxanthin (p. 348) although Schiitzen- 

 berger found both of these bases and also carnin. Salomon found it 

 among the products of the pancreatic digestion of fibrin but it is 

 clear that the latter must have contained an admixture of nuclein 

 (p. 368). 



Together with hypoxanthin, guanin, and possibly adenin, it occurs 

 in many plants, among which may be mentioned lupine, sethalium, 

 sprouts of malt (Salomon, Balke), tea-leaves (Baginsky), gourd seeds, 

 soja beans, etc., in sprouts of Qcer arietinum (Belsung). Xanthin 

 bases are found in sprouts of lupine and of the gourd ; with hypo- 

 xanthin and guanin it occurs in the fir, Pinus sylvestris. Its pres- 

 ence in auto-digested yeast has already been referred to. As pointed 

 out above the presence of xanthin and its derivatives in food, espe- 

 cially in coffee, tea, cocoa, constitutes the chief source of xanthin and 

 of the allied bases in the urine. 



Xanthin on electrolytic reduction yields desoxyxanthin, CgH^ 

 N,0 (Tafel and Ach, 1901). 



It was held by Strecker that xanthin may be obtained by reduc- 

 tion of uric acid with sodium amalgam according to the equation j 



C,H,NP3 -H H, = C,HAO, + H,0. 



Uric Acid. Xanthih. 



This view, however, was not confirmed by Fischer (p. 336). More 

 recently Sundwik claims to have effected the reduction of uric acid 

 to xanthin and to hypoxanthin (p. 337). The reverse operation, 

 the conversion of hypoxanthin into xanthin, likewise reported by 

 Strecker, has not been confirmed by Fischer or by Kossel. It is, 

 therefore, evident that while these bodies apparently form a contin- 

 uous oxidation series with uric acid as the final product, and 

 although this change undoubtedly goes on in the animal economy, 

 yet all attempts to reproduce it in the laboratory by oxidation with 

 potassium permanganate or with nitric acid have yielded only nega- 

 tive results. Nevertheless, in a more indirect way it is possible to 

 convert uric acid into the purin bases and vice versa. This was 



