Volume IV OCTOBER, 1914 No. 2 



OUR PRESENT KNOWLEDGE OF THE CHEMISTRY 



OF THE MENDELIAN FACTORS FOR FLOWER- .„,«ar^ 

 COLOUR. ■ ^^' ^«** 



rt.M aNICM. 

 By M. WHELDALE, oakDBC*, 



Fellow of Newnham College, Cambridge, and formerly Research Student 

 of the John Innes Horticultural Institution, Merton, Surrey. 



Since the inheritance of flower-colour involves, in the majority of 

 cases, the inheritance of some kind of anthocyanin pigment, any know- 

 ledge of the chemistry of the factors for colour must of necessity be 

 concerned with the chemistry of anthocyanin. During the last few 

 years a considerable amount of work has appeared, i.e. that published 

 by Combes, Grafe, Tswett and Willstatter, on the chemistry of antho- 

 cyanin apart from its connection with Mendelian problems. It seems 

 advisable at every stage to bring the results of such work to bear, when 

 f)ossible, upon the evidence obtained by those who have approached the 

 subject more directly from the Mendelian point of view. 



In the present paper an attempt has been made to state, as far as 

 possible, from all the evidence available, exactly how much we know of 

 the chemical mechanism underlying the Mendelian factors for flower- 

 colour. 



The colour varieties of Antirrhinum majus having provided useful 

 material for the chemical interpretation of some Mendelian factors, an 

 account will be first given of the pigments of this species. 



The Varieties of Antirrhinum majus. 



The original wild type of Antirrhinmn majus has magenta flowers, 

 the colour being due to at least seven pairs of factors (Wheldale, 2-5, 26, 

 29 ; Baur, 5, 6), but of these, only four need be mentioned in the present 

 paper, and the type homozygous in all factors may be represented as : 



YYIIRRBB magenta. 



Joum. of Gen. ly 8 



