THE OXIDASES IN RELATION TO PIGMENTATION 273 



When heated with alkali the anthocyanidins are split 

 up as follows : 



Anihocyanidin. Decomposition Products. 



Pelargonidin, C 15 H 10 O 5 . . Phloroglucinol and 2>-hydroxybenzoic 



acid. 

 Cyanidin, C 15 H 10 6 . . . . Phloroglucinol and protocatechuic 



acid. 

 Delphinidin, C 15 H 10 O 7 . . . . Phloroglucinol and gallic acid. 



Of the above, cyanidin is isomeric with the flavones luteo- 

 lin and fisetin, pelargonidin with apigenin; and delphinidin, 

 quercetin and morin are represented by the same molecular 

 formula. 



Willstatter and Everest (1913) have adduced reasons for 

 the belief that anthocyanins unite with alkalies in virtue 

 of the possession of phenolic hydroxyl groups, and form 

 oxonium salts with acids, as in the following scheme, in 

 which I. represents the hydrochloride, and II. represents 

 the free colouring matter, with a pyrone ring. Glucose 

 and other substances may be attached to the free valencies 



as side-chains. 



O 



01 



H VVv 



III III' 



c c c c c c 



o c c 



II 



II. 



Among the earlier workers on pure anthocyanin was 

 Grafe (1911). Crystalline anthocyanin was obtained by 

 him from Pelargonium zonale in rosettes of needles, which 

 melt at 270. It has the empirical formula C 18 H 26 13 , and 



18 



