12 TOXINS AND ANTITOXINS. 



maines they are classed under three groups, accord- 

 ing to their chemical affinities. These groups are 

 as follows: 



i. Xanthic Leucomaines. The bases of this 

 group appear to have a composition resembling 

 that of uric acid. When hydrolyzed, they yield 

 urea and guanidine. They are weak bases, and 

 exhibit both basic and weakly acid properties. 

 They all possess the common characteristic of being 

 precipitated by copper acetate in acid solution with 

 heat, and by ammoniacal silver nitrate in the cold. 



According to Kossel, these bases are derived 

 from the nucleo-albumins which are found in 

 the cell nuclei, and which are, as we know, sub- 

 stances rich in nitrogen and phosphorus. 



Among the bases of this group may be men- 

 tioned adenine, C 5 H 5 N 5 , which is obtained from 

 infusions of tea.* This base is non-toxic; it was 

 discovered by Kossel, f and it crystallizes easily. 



Some others of this group are: 



Guanine, CsHsNsO, non-toxic, discovered by 

 Unger; pseudo-xanthine, obtained from muscular 

 tissues; sarcine, C 5 H4N 4 O, also but slightly toxic, 

 discovered by Scherer; xanthine, C 5 H 4 N 4 O2, 

 which is found in many urines, and which acts as a 

 stimulant on the cardiac muscles; paraxanthine, 



* KRUGER: Bull. Soc. Chim. (3), vm, p. 687. 

 f KOSSEL: Zeitschrift fur physiol. Chim., x, p. 248; and 

 . Soc, Chim. (3), in, p. 239. 



