I/o Plant Pigments [March, 



ready been stated that Carotin can be transformed into xanthophyll 

 by oxidation. It is therefore highly probable that the origin of the 

 latter may be attributed to this action. But how and under what 

 conditions, does Carotin arise ? Here again no answer can as yet be 

 given. 



Flavones. The mother substance of the yellow, water-soluble 

 pigments, flavone, has the Constitution indicated by the formula, 



H H H 



I I I 



I II II \c=c/ 



H— C\, /Cv /C— H I M 

 ^C^ \C/ H H 



I II 



H O 



Most of the flavones are readily synthesized from phenols and car- 

 boxylic acids. On fusion with alkaH they usually yield phloro- 

 glucinol and protocatechuic acid, and sometimes resorcinol and 

 hydroxybenzoic acid. These Compounds may, therefore, be looked 

 upon as giving rise to the flavone coloring matters. 



Anthocyanins. The red and blue coloring matters that can 

 be extracted from leaves, flowers, and fruit by means of water are 

 commonly spoken of as anthocyanins or anthocyans. No good 

 Classification of these substances has as yet been suggested. Will- 

 stätter, who has recently begun to investigate them, and whose work 

 promises to shed much light on the subject, in a recent study of the 

 anthocyan of corn flower (cyanin), has found that it hydrolyzes 

 into two molecules of glucose and one molecule of cyanidin 

 (QsHi.OeCl).^^ 



With regard to the mode of formation of these anthocyanins 

 much of interest has been suggested. Miss Wheldale,^^ by cross- 

 breeding yellow and white forms, obtained anthocyanin products. 

 As the yellow forms were flavone in nature, and the white contained 

 oxidases, Miss Wheldale drew the conclusion that anthocyanins are 

 oxidation products of flavones. Since the flavones are known to 



24 Willstätter : Sitsb. preuss. Akad. Wissenschaften, 1914, xii, p. 402. See 

 also Willstätter and Everest, Ann., 1914, cccci, p. 189. 



25 Wheldale: Proc. Cambridge Phil. Soc, 1909, xv, p. 137; Proc. Roy. Soc, 

 1909, B, Ixxxi, p. 44; Biochem. Jour., 1913, vii, p. 87. 



