192 Oil a Supposed Synthesis of Aiifhocyanin 



oxidation products of flavonols, but were indeed related either to 

 /3-phenyl-benzo-7-pyrone or ;8-phenyl-benzo-a-pyrone, in the manner 

 suggested by the present author {loc. cit), and were derivatives of 

 either I or II, it becomes necessary that the work of Wheldalc and 

 Bassett upon the pigments of Antirrhinum should be continued until 

 crystalline substances having the characteristics of chemically pure 

 compounds are obtained, and these examined, before it can have any 

 weight in favour of the hypothesis which those authors support. 



Doubtless Wheldale and Bassett were neither aware of the publica- 

 tion of Willstatter and his collaborators, nor present when Professor 

 Willstatter lectured on this subject at the University College, London, 

 in May last. 



It is perhaps advisable to note that in the passage quoted by 

 Wheldale and Bas.sett, from the author's paper, viz. : " one would expect 

 that by taking the yellow gluco.'iide, hydrolising, then reducing \vith 

 removal of sugars, the anthocyanidin produced would combine with the 

 sugar present to form an anthocyanin. This is not the case," the 



original reads: " , then reducing xvithout removal of sugars, " 



{loc. cit. p. 445). 



The authoi's recent work proves at least that Rutin — a disaccharide 

 of quercetin — passes by reduction, without hydrolysis at all, into a red 

 disaccharide pigment whose properties are those of an anthocyanin. 

 No satisfactory evidence is available to suggest that, in general, higher 

 glucosides of these pigments occur in plants, and until such evidence is 

 forthcoming, hypotheses demanding their existence are not likely to 

 receive much support from chemists. 



It appears necessary to point out that the author does not use the 

 solubility or insolubility of these pigments in amyl alcohol as a test to 

 distinguish between anthocyanidins and anthocyanins, the test used 

 depends upon the distribution between dilute aqueous sulphuric acid 

 and amyl alcohol, coupled with the change in such distribution when 

 a glucoside pigment is hydrolysed ; this was clearly described in the 

 author's paper (loc. cit). 



Chemical Laboratories, 



Univer.sity College, 

 Reading. 



