THE OXIDASES IN RELATION TO PIGMENTATION 257 



planation if the facts concerning colour production in 

 Primula be borne in mind. The arrows indicate the reac- 

 tions given by the various types of flower : 



OXIDASES OF Gytisus Adami. 

 C. Adami. 



Epidermal direct oxidase, \ / __ / Purple \ __ \ /Bundle direct oxidase, 

 as in C. purpureus j \flowersj ~~ ' \ as in C. purpureus 



Buff flowers 



si/ 



__ __ oxi 



in C. laburnum / ^~ \flowersj "^ \ in C. laburnum 



No epidermal oxidase, as \ __ ( Yellow! __ v /Bundle peroxidase, as 

 / ~ " 



THE RESTORATION OF ANTHOCYAN PIGMENT IN 

 DECOLORIZED FLOWERS. 



Owing to the accumulation of a large amount of experi- 

 mental evidence, the salient features of which have been 

 mentioned in the preceding pages, there was a general con- 

 sensus of opinion that oxidases were concerned in the pro- 

 duction of anthocyan pigments. It was also contended by 

 Keeble, Armstrong, and Jones (1913, 1), that the return of 

 colour which takes place when a flower decolorized in 

 alcohol is transferred to water, is explicable in terms of 

 oxidase action. This view has recently been opposed by 

 Wheldale and Bassett (1914, 1), and by Tswett (1914), while 

 Wills tatter (1913) has brought forward yet another explana- 

 tion of the phenomenon. 



Keeble and Armstrong attributed the decoloration to the 

 action of the reducing agents of the tissue containing the 

 anthocyanin. They conceived the normal colour to be due 

 to a balanced reaction between the oxidase and the re- 

 ducing substance, but, owing to the lessening of enzyme 

 activity occasioned by the application of strong alcohol, 

 equilibrium is displaced in favour of the transformation 



17 



