158 Miss Wheldale, On the nature of anthocyanin. 



foctor, in the factor modifying this to ivory and in R, the 

 reddening factor, we find the proportion of anthocyanic, i.e. 

 magenta and crimson individuals, to the non-anthocyanic, i.e. 

 ivory, yellow and white, is again as 9:7. 



Of the non-anthocyanic, the proportion of those carrying G, 

 i.e. ivories and yellows, to those carrying R, i.e. true albinos, 

 is again as 1:1. 



Through the kindness of Professor Bateson and Mr R. P. Gregory, 

 who have been working for some time upon the inheritance of 

 fiower-colour in Primula sinensis, I have lately been able to 

 examine a number of varieties of this genus. The flowers of 

 white varieties contain, as stated on p. 151, achromogen apparently 

 of the nature of a flavone. Capability to produce red pigment — 

 anthocyanin — is probably due to the presence of an oxydase in the 

 plant ; hence a white variety has either lost the power to produce 

 the oxydase or contains a positive fjictor — an inhibitor or re- 

 ductase — which prevents the formation of the pigment. 



It is possible, on the one hand, that the loss of the oxydase 

 gives rise to certain white-flowered varieties with green stems. 

 These varieties are known as 'recessive whites'; mated with a 

 full-coloured variety, such as deep crimson or magenta, they give 

 a full-coloured F^. On the other hand, the presence of an in- 

 hibitor in th.e jioiuer only (as suggested by Bateson and Gregory), 

 may be the explanation of the existence of certain white-flowered 

 varieties having red stems; these varieties are termed 'dominant 

 whites' and mated with a full-coloured variety give an F^^ which is 

 only tinted. 



When anthocyanin is present, two series of varieties are 

 distinguishable, a magenta series and a crimson series, the former 

 being epistatic to the latter. As previously stated, the same two 

 series, magenta and crimson, occur in Antirrhinum and are probably 

 due to the action of an oxydase on the pale yellow flavone of the 

 ivory and the deep yellow flavone (xantheiu) of the yellow varieties 

 respectively. In Primula no yellow (xanthe'ic) variety arises from 

 the crimson but loss of oxydase from crimson and from magenta 

 gives whites indistinguishable to the eye, though those thrown 

 by magenta contain of course, the magenta factor. 



I have examined the magenta and crimson pigments and also 

 the whites derived from each series. Whites from magenta appear 

 to carry a chromogen giving a more intense yellow with alkalis 

 than those from crimson ; hence magentas give, on the whole, 

 a green colour with alkali, due to the blueing of the anthocyanin 

 and the yellowing of the unaltered chromogen. The crimsons 

 give a bluer colour with alkali due to the far slighter yellowing 

 of the unaltered chromogen. The action of iron salts on the 

 crimson pigment resultg in a brown, on the magenta in a green 



