o7H Chemistrif of Menddian Factors for Floiver -Colour 



anthocyanin and the artificial pigment prepared from the same Havone. 

 Only in Antirrhinum are such relationships knuwn and they arc not so 

 far in accordance with the reduction hypothesis. 



Willstjitter dismisses as disproved the hypothesis suggested by the 

 author" some years ago, with a view to explaining some of the phe- 

 nomena, both physiological and chemical, of anthocyanin production. 

 The hypothesis supposes several of the hydroxyls of the flavones in tlie 

 living cell to be replaced by sugar and that only after hydrolysis of 

 certain hydroxyls can changes take place at these points with the 

 production of pigment. The hypothesis is more within the province of 

 plant physiology than chemistry and was the outcome of observations 

 upon the distribution of pigment in the tissues and the effect of factors 

 such as light, temperature, drought, injury, sugar feeding, etc., on 

 anthocyanin formation. The hypothesis has been said to be rendered 

 valueless by the fact that in the formation of artificial anthocyanin, 

 mono- or even di-glucosides of flavones can be employed and the pig- 

 ment is formed on reduction in the cold without hydrolysis. 



The existence of stable di-glucosides of quercetin which can be 

 isolated and which, when treated in hot acidified alcoholic solution 

 with nascent hydrogen, give a red product is no criterion of the con- 

 ditions in which the quercetin exists in the living cell, nor of the 

 reactions which convert it into anthocyanin. 



Note. I should like to take this opportunity of correcting two errors 

 made by me in a previous paper written jointly with Mr Bassett, i.e. "On 

 a supposed Synthesis of Anthocyanin " and published in this Journal, 

 Vol. IV. No. 1, p. 103. 



On page 104, line 3, of the above paper, read : 



" glucoside (of flavone) -I- water '*~7 chromogen (flavone) 



+ sugar X (flavone) + oxygen = anthocyanin." 



On Jjage 105, line 9, read : 



" then reducing without removal of sugars." 



' Wheldale, M., " On the Formation of Anthocyanin." Journal of Genetics, Cambridge, 

 1911, Vol. I. p. 133. 



CAMBRIDGE: PRINTBD BY JOHN CLAT, U.A. AT THE UNIVEBSITY PRESS 



