CHAPTEE XII. 



CHEMISTEY OF THE LEUCOMAINES. 



Under this head are classed those basic substances which 

 are found in the living tissues, either as the products of 

 fermentative changes or of retrograde metamorphosis. 

 Most of these substances have already been known for 

 many years, though their real significance as alisaloidal 

 bodies, and their relation to the functional activities of the 

 animal organism have been but little understood, or rather 

 they have not been brought together under the leading 

 conception that they are alkaloidal products of physiologi- 

 cal change. The first attempt at the systematic study and 

 generalization of these basic substances was made by 

 GrAUTiEK, who applied to them the name leucomaines, a 

 term derived from the Greek ^^x<^i^<^, signifying white of 

 eggs. Under this name he includes all those basic sub- 

 stances whicih are formed in animal tissues during normal 

 life, in contradistinction to the ptomaines or basic products 

 of putrefaction. The distinction between vegetable and 

 animal alkaloids is not very well defined, and, in fact, there 

 seem to be reasons for considering their formation as due 

 to the same causes which bear an intimate relation to the 

 physiology of the cells and tissues of both kingdoms. 

 Thus, vegetable tissues are known to contain not only 

 definite ptomaines, such as choline, but also leucomaines, as 

 hypoxanthine, xanthine, etc. Indeed, in this latter group 

 must be placed, on account of their relation to xanthine, 

 those well-defined alkaloidal bases, caifeine and theobro- 

 mine. Not only are the representatives of these two 

 divisions of basic substances common to both kingdoms, 

 but their parent bodies, lecithin, nuclein, etc., are known 

 to occur in both, thus giving rise to the same bases on 

 decomposition. 



