CHLOKOPHYLL. 221 



Xauthine. 



NH CH 



I II 

 CO C NHL 



I >co 



NH C = N / 



The alkaloids are as a rule poisonous and are of no value as 

 direct foods, though their presence in food stuffs, e.g., tea, &c., 

 is of great importance. 



VII. CHLOEOPHYLL. 



This substance is the essential constituent of all the green- 

 coloured portions of plants and is the medium by which the 

 assimilation of carbon compounds from carbon dioxide and 

 water by the aid of energy derived from light takes place. 

 Its chemical composition and constitution are not well known, 

 though they have been the subjects of an immense amount of 

 research. According to Schunck and Marchlewski the chloro- 

 phyll obtained from all varieties of plants is the same. Other 

 observers, e.g., Etard, consider that many different chlorophyll- 

 like bodies occur. 



The constitution of chlorophyll resembles that of the colour- 

 ing matter of blood, and both substances are probably deriva- 

 tives of pyrrol, C 4 H 5 N ::: = 



CH CH 



CH CH 



Chlorophyll is readily extracted from plants by ether, carbon 

 disulphide, or alcohol. By the action of hydrochloric acid 

 chlorophyll is converted into phylloxanthine, which on further 

 treatment with acid yields phyllocyanine. These substances, 

 as their names imply, possess a yellow and blue colour respec- 

 tively. 



By further action of hydrochloric acid or of alkalies phyllo- 

 cyanine is converted into phyllotaonin, a crystalline body having 

 a composition corresponding to the formula C 40 H 88 NO 5 .t 



* Schunck and Marchlewski, J.C.S. 1896, abst. i. 574. 

 t Schunck and Marchlewski, J.O.S. 1894, abst. i. 341. 



