272 NITROGEN BASES 



tioned ; in the higher animals there is a definite eh'mination of 

 these waste nitrogenous substances from the organism, and 

 the output bears a definite relation to the amount of proteins 

 taken as food. In plants, on the other hand, there is no 

 general elimination of nitrogenous waste, such substances 

 being used up in anabolic processes. Thus Weevers,* whilst 

 recognizing that caffeine and theobromine may be the pro- 

 ducts of the decomposition of proteins, considers that they are 

 reorganized, and are therefore not to be classed as waste pro- 

 ducts in the same sense as uric acid is. It will, of course, be 

 noticed that there is relatively much more nitrogen in these 

 compounds than in the proteins. 



Finally, some of the substances in question may be of bio- 

 logical importance as a protection against herbivorous animals 

 and parasitic fungi. 



No suggestions of any real value other than those already 

 mentioned have as yet been made concerning the source from 

 which these substances are synthesized, although, as pointed 

 out by Meldola,f the discovery that glucose could by the action 

 of ammonia in the presence of zinc hydroxide be converted 

 into methyliminazole, I renders the genesis of some of the 

 natural alkaloids which contain the iminazole ring at any rate 

 a chemical possibility. 



* Weevers: " Proc. Koningkl. Akad. Wetens.," Amsterdam, 1903, 369; 

 "Ann. Jard. Bot. Buitenzorg," 1907, 21, i. 



tMeldola: "J. Chem. Soc, Lond.," 1906, 89, 764. 



JWindausand Knoop : " Ber. deut. chem. Gesells.," 1905, 38, 1166. 



FURTHER REFERENCES. 



Brieger: " Ueber Ptomaine," Berlin, 1885-6, I. -III. 



Cordin: " Ber. deut. chem. Gesells.," 1899, 32, 2871. 



Pictet : " Pflanzenalkaloide," Berlin, 1900. 



Schmidt : " Die Alkaloidchemie," Stuttgart, 1900-4; 1904-7 and 1907- 



Winterstein and Trier : " Die Alkaloide," Berlin, 1910. 



