PHOSPHOROUS SUBSTANCES OF THE CELL. 135 



very many organs, e.g., from the nuclein of yeast (Kossel 1 ), 

 from the nucleic acid prepared from ox-spermatozoa, or 

 again from that of carp-spermatozoa. It has also been 

 obtained from the spleen, the pancreas, the thymus, etc. 



2. Guanin, C 5 H 5 N 5 0, has been prepared from the nuc- 

 lein of yeast (Kossel), and from the nucleic acid prepared 

 from thymus (Kossel), and from that of salmon-spermatozoa 

 (Miescher). It has also been obtained from numerous 

 cellular organs, e.g., liver, spleen, pancreas, etc. It is 

 closely related to xanthin, into which it may be converted 

 by the action of nitrous acid when an imido-group ( = NH) 

 of the guanin is split off and an O atom inserted in its 

 place. 



3. Hypoxanthin, C 5 H 4 N 4 0, has been found in the same 

 position as xanthin, and in especial quantity in salmon 

 sperm (Miescher). It has been prepared from the nuclein 

 of leucocytes (Kossel") and of yeast (Kossel y ). 



4. Adenin, C 5 H 5 N 5 , was first discovered by Kossel, who 

 obtained it from the pancreas. He further obtained it from 

 thymus-nucleic acid 4 and from the nuclein of yeast. It 

 stands in the same relationship to hypoxanthin that 

 guanin does to xanthin. 



C 5 H 5 N 5 + HNO a = C 5 H 4 N 4 + N 2 + H e O 

 and C 5 H 5 N 5 q + HN0 2 = C 5 H 4 N 4 2 + N 2 + H 2 0. 



The finding of these bases in this position is particularly 

 of interest in conjunction with their close relationship to 

 uric acid (C 5 H 4 N 4 3 ), which only differs from xanthin in 

 possessing one more oxygen atom. Their molecular struc- 

 ture too is similar, and just as with uric acid they are found 

 to split up into alloxan, parabanic acid, etc., under the in- 

 fluence of oxidising agents. With regard to the part they 

 may play in the formation of uric acid in the body we will 

 return later. 



Cytosin.- — Associated with these bases though not 

 showing exactly the same properties is another base, 



1 Kossel: Ztschr.f. physiol. C/iem., Bd. 4, S. 290, 1880. 



2 Kossel: Ibid., Bd. 5, S. 152, 1881. 



3 Kossel : Ibid., Bd. 4, S. 290, 1880. 



4 Kossel : Ber. d. d. chetti. Ges., Bd. 26, S. 2753, 1893. 



