150 Dr. A. E. Everest and Mr. A. J. Hall. 



then it would appear that one of the effects of the introduction of oxygen is 

 to diminish the part played by water in the reactions. 



In conclusion we wish to express our thanks to Prof. F. Gowlaud Hopkins, 

 in whose laboratory this work was done. 



Anihocyanins and Anthocyanidins. Part IV.- — Ohservations on : 

 (a) Anthocyan Colours in Flowers, and (b) the Formation of 

 Anthocyans in Plants. 



By Arthur Ernest Everest, D.Sc, Ph.D., F.I.C, and Archibald John 



Hall, B.Sc, A.I.C. 



(Communicated by Prof. F. Keeble, F.R.S. — Received February 2, 1921.) 



In a recent paper, Shibata, Shibata and Kasiwagi,* dealing with the question 

 of the colours observed in flowers, and the condition of the anthocyan pigments 

 as they exist in plants, arrived at conclusions that differ considerably from 

 those of Willstatter and of Everest. In view of this, and of the fact that 

 Shibata, Shibata and Kasiwagi's paper has passed into reviews, the present 

 authors feel that the publication of some observations that they have made, 

 both before the publication of the paper referred to, and since receiving it, as 

 confirmation of the present authors' results and extension of the field, will not 

 be out of place. 



Results of experiments upon the formation of anthocyan pigments are also 

 described, and important conclusions drawn from them. 



The Constitution of the Blue Anthocyan Pigments in Flowers. 



Willstatter and Everestt as the result of their examination of the pigments 

 of the cornflower and of preliminary investigations upon other flowers, 

 concluded that the blue colour in the cornflower was due to an alkali, or 

 alkali-earth, salt of a phenolic substance which was violet in the free state, 

 and which was also capable of forming red oxonium salts with acids. This 

 simple explanation of the main colour changes being due to changes in the 

 condition of the cell sap in the plants concerned, has been elaborated by 

 Willstatter and Mallisonj to show how such a supposition, coupled with the 



* ' J. Amer. Chem. Soc.,' vol. 41, p. 208 (1919). 

 t 'Ann.,' vol. 401, p. 189 (1913). 

 + 'Ann.,' vol. 408, p. 147 (1915). 



