1 64 CHEMISTRY OF THE YEAST CELL. 



N = C . H 



I I 

 H. C C — N.H 



il II \c H 



Purin. 



H. N— C : H.N— C : 



II' 11 



C:C C-N.H H.C C-N.H 



I It \p TT II II ^C H 



Xanthin. Hypoxanthin. 



C5H4N4O0. CgH4N40. 



2-6-dioxy-purin. 6-monoxT-purin. 



H. N-C : O N = C . NHo 



II 11 



NHo.C C— N.H H.C C— NH 



11 II \p H II il \o H 



Guanin. C5H5N3O. Adenin. CsHgNs. 



2-amino-6-oxy- 6-amino-purin. 



puiiii. 



They accordingly belong to the large group of purin bases. 

 On the other hand, Thymin and Ascoli's yeast nuclein base are 

 of more simple construction : — 



H.N — C:0 H.N— C:0 



II II 



: C C . H : C C . CH3 



I II I II 



H.N— C.H H.N-C.H 



Ascoli's base. C4H4N.2O2. Thymin. CsHgNsOo. 



Uracyl. 5-methyl-uracyl. 



Of these, thymin seems the most widely diffused, since only 

 three nucleins not containing this base are known, one of them 

 being yeast nucleic acid. The second is the above-mentioned 

 guanylic acid, which, according to I. Bang (L), furnishes guanin 

 alone (and of this about 35 per cent, by weight). The third is 

 inosinic acid, which was discovered by Liebig in meat juice, and 

 which, according to the experiments made by F. Hasier in 

 1895, probably contains hypoxanthin solely. 



The percentage content of xanthin, guanin, hypoxanthin, 

 and adenin (of course in the combined condition specified) in 

 yeast, was first asceitained by S. Schindleh (I.) by the aid of his 

 quantitative method of separation, and was found to be 0.024, 

 0.029, °-093) ^^^^ 0.043 grii™ respectively per 100 grams of pressed 

 yeast, the character of which was not more accurately defined. 

 These values should not be considered as more than merely 

 approximate, the reliability of analytical methods having been 

 proved doubtful by 0. Wulf (I.). 



