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The Formation of the Anthocyan Pigments of Plants. — Part VI. 



By Frederick Keeble, Sc.D., F.E.S., Professor of Botany, University College, 

 Beading ; E. Fraxkland Armstrong, D.Sc., Ph.D., and W. Xeilsox 

 Jones, M.A., Lecturer in Botany, University College. Beading. 



(Received June 16— Bead June 26, 1913.) 



In the previous communications of this series we have recorded the results 

 of observations on the oxydases and chromogens concerned with the produc- 

 tion of anthocyan pigments. The study of pigment formation is continued 

 in the present communication, the sections of which deal with the following 

 subjects : — 



1. A pigment-producing glucoside of the wallflower (Cheiranthus cheiri). 



2. The formation of pigment-producing substances from glucosides. 



3. The biochemistry of Mendelian colour characters. 



Section 1. — A Pigment-producing Glucoside of the Wcdljlovjer. 



It is customary to divide the sap-pigments of plants into two series, the red, 

 purple, and blue anthocyan pigments, and the yellow xanthein pigments. 

 Miss Wheldale* has, however, suggested, on p-enetical grounds, that the 

 anthocyan and xanthein pigments are related with one another. This author 

 points out that most plants contain colourless or pale yellow substances which 

 give a canary yellow colour with ammonia. 'When heated with dilute acid 

 they assume a deep yellow colour aid reduce Fehling's solution. Hence, 

 they are to be regarded as glucosides.f 



Miss "Wheldale suggests that anthocyan is a compound of such a glucoside- 

 like body with a " reddening " substance. In the absence of the latter and 

 with the loss of a further substance (the sugar ?), the glucoside gives rise to a 

 yellow xanthein pigment. 



More recently.^: Miss Wheldale states that the yellow pigments are largely 

 present as glucosides, of which some, or possibly all, the hydroxyl groups 

 are replaced by sugar. Specific hydrolysis may act on hydroxyl groups in 

 certain positions, and when these groups are free from sugar, oxidation, 

 and possibly condensation, may take place at these points. The residual 

 hydroxyl groups in the anthocyan molecule would probably be replaced 

 by sugar, and hence the anthocyans would occur as glucosides. 



* ' Eoy. Soc. Proc.,' 1909, B ; vol. 81, p. 44. 



t Compare Czapek, ' Biochem. d. Pflanzen,' vol. 1, p. 177. 



% ' Biochem. Journ.,' 1913, vol. 7, p. 87. 



