158 Dr. A. E. Everest and Mr. A. J. Hall. 



The present paper describes an attempt made by the authors to indicate 

 which of these possible processes of synthesis is in reality adopted by 

 Nature. 



If Robinson's suggestions are correct, then in those flowers which contain 

 anthocyan pigments, it would be anticipated that the colour of the anthocyan 

 would develop before any trace of flavonol could be detected. No published 

 observations are yet available to support this, and the present results indicate 

 that the opposite is the case. Further, even pale yellow, or white, flowers 

 which contain flavonol derivatives but no anthocyans, would be expected to 

 pass through a stage in which they were coloured by the anthocyans from 

 which the flavonols were to be formed ; unless it is assumed that the trans- 

 formation from anthocyan to flavonol, in such cases, is always complete, and 

 proceeds more rapidly than the formation of anthocyan. 



If on the other hand flavonols are first synthesized in Nature and antho- 

 cyans formed from them only in those cases where the conditions for reduction 

 are available, then the stages would be simplified. In the pale yellow or 

 white petals containing flavonols there would be gradual development without 

 marked colour changes. This is what occurs. In the flowers which are 

 coloured by anthocyans it may well be expected that at least in most cases the 

 very small buds will be pale yellow, or colourless, and that a certain amount 

 of flavonol will be developed before the anthocyan is formed and becomes 

 obvious by its tints. The present investigation proves that this is the case. 

 Moreover, it is likely that flavonols would be found alongside anthocyans in 

 flowers containing the latter. Published observations agree with this. 



The authors consider that the present results strengthen the evidence that 

 the anthocyan pigments are formed from flavonols. Only by assumptions 

 such as that indicated above, could the reverse be reconciled with the 

 experimental evidence at present available. 



Experimental. 



As myricetin was not available to the authors, and Shibata, Shibata and 

 Kasiwagi state in their paper that the reduction of quercetin or of quercitrin 

 proceeds "just the same as myricetin or myricitrin," the authors carried out 

 a reduction of quercitrin under exactly the conditions given in the paper of 

 the above mentioned authors. The result was that a green solution having 

 bright green fluorescence was obtained from which a green pigment (mixture 

 of pigments) could be precipitated by means of ether. The green precipitate 

 remained green on washing with ether. An exactly similar result was 

 obtained if the reduction was carried out by means of a very small amount of 



