A GENE TICO-PH Y SIOLOGIC AL STUDY ON THE FORMATION ETC. 
3 
acidified to check the formation of the colourless isomer, is mixed with the 
solution containing active oxidizing enzymes, the characteristic red colour 
diminishes gradually and finally becomes pale yellow or practically colourless. 
The aqueous solutions of hydrogen peroxide and certain other inorganic oxidiz¬ 
ing agents have the same effect as the enzyme. Such phenomena have been 
observed by Bouffard (1902), Kastle (1905), Kastle and Haden (1911), 
Combes (1913), Atkins (1916) and Nagai (1917). 1 
The reversible change of flavone to the coloured substance of anthocyanin- 
like nature by means of reducing and oxidizing agents respectively has been 
observed by many. Allen (1901)' stated that when an acidified (by hydro¬ 
chloric acid) alcoholic solution of quercetin was treated with sodium amalgam 
the liquid assumed a fine purple colour and on concentration yielded red 
prisms which dissolved in alcohol and a little alkali forming a green solution, 
the solution being readily reoxidized with formation of quercetin on exposure 
to the air. Combes (1913)°’ observed a similar reversible change in the yellow 
pigment isolated from the leaf of Ampélopsis hederacea. 
In the study of anthocyanin in the corn flower, Willsatätter and 
Everest (1913) 4 found that when an alcoholic solution of cyanidin was 
warmed with dilute hydrogen peroxide solution, the colour diminished. When 
it was again warmed on the water bath with the addition of a few drops of 
dilute hydrochloric acid, the liquid became yellow, and by extracting with 
ether, beautiful bright yellow crystals were obtained which when treated with 
alkalies, yielded a deep yellow solution. Miss Wheldale (1914) 5 attempted 
1. Bouffard, A., Action de F acid sulfureux sur l’oxydase et sur la matière colorante du vin 
rouge. Comp. Rend. Acad. Sei. Paris. 134 : 1380, 1902. Kastle, J. H., A Method for the Deter¬ 
mination of the Affinities of the Acids Colorimetrically by Means of Certain Vegetable Coloring 
Matters. Am. Chem. Jour. 33 : 46, 1905. Kastle, J. H. and Haden, R. L., On the Color Changes 
Occurring in the Blue Flowers of the Wild Chicory, Cichorium intybus. Am. Chem. Jour. 36 ; 
315, 1911. Combes, R , Passage d’un pigment anthocyanique extrait des feuilles rouges d’automne 
an pigment jaune contenu dans les feuilles vertes de la meme plante. Comp. Rend. Acad. Sei. 
Paris, 152 :1454, 1913. Atkins, W. R. G., Recent Researches in Plant Physiology. 1916. Nagai, 
I , The Action of Oxidase on Anthocyanin. Bot. Mag. Tokyo, 31:65, 1917. 
2. Allen, A. F., Commercial Organic Analysis. Vol. Ill, Part 1, 440, 1901. 
3. Combes, Eoc. cit. 
4. WiLLST ätteb , R. and Everest, A. E., Ueber den Farbstoff der Kornblume. Liebig. Ann. 
401 :189, 1913. 
5. Wheldale, M., Our Present Knowledge of the Chemistry of the Mendelian Factors for 
Flower Colour, Jour. Genet. 4 ; 109, 1914. 
