252 SOME RECENT RESEARCHES IN PLANT PHYSIOLOGY 



be widely distributed. On this view the anthocyanins 

 are a group of related substances, differing individually 

 according to the flavone from which each one has arisen. 

 Palladin's view that the anthocyanins are related to the 

 respiratory chromogens does not appear to differ funda- 

 mentally from Wheldale's, but the latter is far more 

 precise. 



The hypothesis may be summarized in the following 

 scheme : 



glucoside (of flavone) + water^ZZ^chromogen (flavone) 



+ sugar (by action of a glucoside-splitting enzyme 



possibly). 

 x (flavone) + oxygen =anthocyanin (the oxygen being 



supplied from an organic peroxide by means of a 



peroxidase). 



The amorphous nature of some of the anthocyanins is 

 considered by Wheldale and Bassett (1914, 1) to point to 

 their high molecular weight, and direct determinations 

 confirm the supposition. The high molecular weight in- 

 volves the condensation as well as the oxidation of the 

 relatively simple flavones, and in this respect the hypoth- 

 esis has sometimes been misquoted. The importance of 

 the condensation is seen from the fact that the production 

 of anthocyanins from flavones has only recentlybeen success- 

 fully accomplished, though if it were a matter of simple 

 oxidation or reduction the change should be readily 

 effected. Willstatter has, however, obtained by the reduc- 

 tion of quercetin considerable quantities of allocyanidin, 

 accompanied by a small amount of cyanidin. The latter* 

 he believes to be identical with the compound obtained by 

 hydrolysis of cyanin, the diglucoside anthocyanin of the 

 cornflower. Combes (1913), Tswett (1913), and Everest 

 (1914, 1 and 2), have also obtained substances by reduction 



