278 SOME RECENT RESEARCHES IN PLANT PHYSIOLOGY 



possible to obtain from an anthocyanin-yielding tissue, 

 before the colour had actually appeared, a substance 

 which could be made to afford anthocyanin. Experiments 

 with Ampelopsis hederacea resulted in his obtaining from 

 the red leaves a substance which crystallized in rosettes 

 of violet-red needles, and gave an insoluble green lead salt 

 upon the addition of neutral lead acetate. From the green 

 leaves, on the other hand, a compound crystallizing in 

 rosettes of needles was also found, but it was of a yellowish- 

 brown colour and gave a yellower lead salt. By treating 

 an alcoholic solution of the yellow crystals with hydro- 

 chloric acid and sodium amalgam, he succeeded in obtain- 

 ing a purple-red-coloured solution which gave rosettes of 

 needles of the same hue. A number of reactions studied 

 by Combes gave identical results with both the artificial 

 red substance and the natural anthocyanin, to such an 

 extent that Combes believes the former to be nothing 

 else than the natural pigment. Since this has resulted 

 by the use of a reducing agent, sodium amalgam, he 

 points out that all previous theories as to the forma- 

 tion of anthocyanin involving an oxidation must be 

 erroneous. 



Everest (1914, 1 and 2) also has obtained coloured com- 

 pounds, which he considers to be anthocyanins, by the 

 reduction of the flavones quercetin, morin, and luteolin, 

 and of extracts from the following flowers viz., daffodil, 

 primrose, viola (yellow), and wallflower (lemon-yellow). 

 The method found to be most satisfactory was to reduce 

 the compound dissolved in a mixture of 5 volumes of abso- 

 lute alcohol and 1 volume of concentrated hydrochloric 

 acid. by means of magnesium ribbon or turnings. As 

 reasons for his statement that these bodies are identical 

 with natural anthocyanins, Everest adduces the similarity 

 of their behaviour in dissolving in amyl alcohol, in giving 



