124 Chemistry of Mendelicm Factors for Flower-Colour 



This method was also tested on pure anthocyanin from Antirrhinum. 

 The pure pigment, prepai-cd by methods previously descrilied and 

 entirely free from flavone, was treated in a similar way with hydrogen 

 peroxide. The colour disappeared, giving a yellowish-brown solution 

 and precipitate, but from neither solution nor precipitate could any 

 flavone be extracted. From this it would appear that no flavone is 

 formed by the action of hydrogen peroxide on the anthocyanin of 

 Antirrhinum. 



Observations of a similar kind to those made by Combes on the 

 effect of sodium amalgam on acid alcohol solutions of flavone.s have 

 also been made by Keeble, Armstrong and Jones (19). By treating 

 the alcoholic extracts of various flowers with zinc dust and hydrochloric 

 acid they obtained results which may be summarised as follows : 



Tsw(!tt (23, 24) also has obtained a red pigment by treating colour- 

 less extracts of apples with strong mineral acids in the presence of 

 formaldehyde or acetic aldehyde. A careful examination of this 

 artificial anthocyanin showed it to have very similar properties to 

 natural anthocyanin. The chief point of difference appears to be its 

 solubility in ether, for natural anthocyanin is insoluble in this medium, 

 unless, according to Tswett, it has stood with hydrochloric acid for 

 3 — 5 days. In addition Tswett obtained similar n'd pigments, though 

 he did not study them in detail, from pears (aldehyde not necessary), 

 white grapes, bananas, flesh of red grapes, white petals of roses and 

 Cyclamen. Negative results, however, were obtained with leaves of 

 white cabbage, mesophyll of red cabbage, Pelargonium leaves, orange 

 peel, petals of white pinks, white petals from buds of red pinks, flowers 

 of lily of the valley, carrots, potatoes, Kohlrabi, and barley seedlings. 



The reaction which underlies some, if not all, of the above phenomena 

 is the following: when the alcoholic solution of some flavones is warmed 

 and acidified with strong hydrochloric acid and sodium amalgam or zinc 



