M. Wheldale and H. Ll. Bassett 105 



from the plant by means of amyl alcohol and this, as Everest notes, is 

 contrary to all observation. 



But, as stated above, it is not suggested in Wheldale's hypothesis 

 tliat anthocyanins or Havones are at any time entirely free from sugar 

 so that the hj-pothesis is not, on this point, in contradiction to observed 

 facts. 



Further, still on the incorrect interpretation of the hypothesis, 

 Everest states, " one would expect that by taking the yellow glucoside, 

 hydrolysing, then reducing with removal of sugars, the anthocyanidin 

 produced would combine with the sugar present to form an anthocyanin. 

 This is not the case." Under any circumstances this criticism would 

 be of no value as it is well known that glucosides are not formed in 

 vitro, except in a few cases under very special conditions such as are 

 certainly not realised in the above experiment. 



There is however yet another point, namely that Everest maintains 

 that no hydrolysis at all of flavone glucosides is necessary as a pre- 

 liminary to the formation of anthocyanin (glucosidal). For he obtains 

 anthocyanin from extracts of many plants containing flavones as gluco- 

 sides by simple reduction in the cold (though this result was not 

 obtained with artificial quercitrin, a glucoside of quercetin). The value 

 of this criticism depends on whether the products formed by reduction 

 are really anthocyanins. 



This question must now be considered, and forms the second main 

 part of Everest's paper. The reactions described are as follows. When 

 the flavones, quercetin, morin and luteolin are treated, in alcoholic 

 solution acidified by hydrochloric acid, with nascent hydrogen formed, 

 for instance, by the action of sodium amalgam, a purple-red or red 

 colour is produced. In the case of quercetin (we do not know whether 

 this is equally true for morin and luteolin) the red product gives with 

 alkalies a gi-een reaction similar to that given by anthocyanin. 



Everest has prepared these red substances from quercetin and from 

 various plant extracts. When quercetin was used t~he red product was 

 soluble in amyl alcohol — hence it was regarded as an anthocyanidin. 

 When plant extracts were employed, the red product was insoluble in 

 amyl alcohol — hence it was considered to be an anthocyanin. 



Everest apparently assumes the red products to be anthocyanins or 

 anthocyanidins, as the case may be, solely on the basis of the gi'een 

 reaction with alkalies, since the mere fact of the solubility or insolubility 

 of the substances in amyl alcohol cannot be taken as evidence of their 

 anthocyanin nature. 



