PUBIN BASES. 335 



The pyrimidin group may be considered as antecedents or per- 

 haps more correctly as cleavage products of the purin bodies. It 

 is represented by the following : 



Pyrimidin, QH^N,. A body, CeHjNPi. 



Ubacil, C^HjNjOj. Episarkin, QHsNsO. (7J 



6-Methyi, TJraoii,, CjHjNjOj (Thymin). Pbeudoxanthin, CiHsN^O. (?) 



The hexon bases proper are only three in number. To these may 

 be appended a lower homologue, two amines and a related acid 

 which may be looked upon as cleavage products of the hexons. The 

 third group then will include : 



Aroinin, CjHijNiOj. Pyrrolidln Carbonic Acid, CsHgNOj. 



HisTiDiN, CjHgNaOj. Gerontin, CsH^Nj. 



Lysin, CeHijiNjOj- Spermin, CjHjN (?) 



Ornithin, CjHijNjOj. Methyl QtriNOLiN, CjoHgN. 



The members of the fourth group have all been discovered by 

 Gautier and by him are regarded as allied to creatin and creatinin. 

 These two substances, especially the latter, have been hitherto 

 regarded as strongly basic in character, but Salkowski has shown 

 that creatinin, when perfectly pure, possesses little or no alkaline 

 reaction, and, moreover, does not combine with acids. In structure 

 and properties it approximates the pyrimidin bodies. The bases in 

 this group are : 



(CREATrNIN, C4H,NsO). 



I Creatin, CjHjNaOj). 



Ceuso-ceeatinin, CsHgNjO. 



Xantho-creatinin, CjHioN^O. 



Amphi-obeatin, CjHijNjO^. 



Base, C^Hj^NioOs. 



Base,; C^H^sN^Oj. 



Besides these two general classes of leucomai'ns, there may be 

 made a fifth class of undetermined leucomai'ns, embracing those 

 bases which have been observed, but studied more or less incom- 

 pletely, in the various physiological secretions of the body. 



PURIN BASES. 



The substances included under this head were formerly spoken of 

 as xanthin bases because of their relation to xanthin, the earliest 

 known member of the group. Subsequently, the term nuclein bases 

 was employed to designate the original four xanthin bases, inasmuch 

 as they are derived from the nucleins. The latter on decomposition 

 with acids yields one or more of these basic products. Kossel and 

 Kriiger, in 1894, suggested a new term based upon the fact that the 

 xanthin bases like uric acid contain alloxan and urea groups. They 

 designated therefore these as alloxuric bases. On the other hand the 

 expression " alloxuric bodies " was made to include uric acid as well 

 as the xanthin bases. 



