Miss Wheldale, On the nature of anihocyanin. 157 



Pigment soluble in Basic lead Iron 



water only acetate Alkalis salts 



yellow (purple with ammonia) . . . reddish 



Amaranthxis sp orange-red.. 



Mirabilis Jalapa „ 



Bougainvillea glabra . . . red 



Phytolacca decandra ... orange-red.. 

 Portulaca grandiflora ... „ 



purplish-green 

 yellow 



There is evidently a tendency for the iron-greening reaction 

 to disappear as the pigment becomes more oxidised. 



Collectively the results so far obtained as to the nature of 

 ' anthocyanin ' may be brought to bear upon the phenomena 

 observed in the genetics of flower-colour. In Lathyrus and 

 Matthiola (Bateson, Saundees and Punnett*) red colour is 

 produced by the meeting of two factors G and R, of which G 

 has been regarded by the authors as possibly representing a 

 chromogen, and R the presence of an enzyme acting upon this 

 chromogen with the production of red pigment. If either the 

 chromogen or the enzyme be absent, then the plant has lost 

 the power of producing red pigment and constitutes an albino. 

 Moreover an additional factor B can be carried by the albino and 

 B CO- existing with G and R can produce a blueing of the red 

 pigment. It seems possible that B may again be an enzyme 

 acting upon the red pigment to produce a bluer oxidation product 

 as we have seen in Althaea; in which, according to Grafe, there 

 are two pigments, one the oxidation product of the other. 



In Antirrhinum the albino (as regards anthocyanin) carrying 

 G, the chromogen, is distinguishable to the eye as the ivory-white. 

 In the true albino no chromogen is present and no aromatic 

 compound can be detected, but since the mating of an ivory-white 

 with an albino carrying R produces a magenta cross-bred, the 

 true albino probably carries the oxidising enzyme. 



In the yellow variety of Antirrhinum a similar yellow aromatic 

 substance is present as a derivative of that in the ivory ; the 

 oxidation process in this case gives crimson as a result either 

 of the production of a different pigment or of red colouration 

 in the presence of unaltered yellow chromogen. 



In Lathyrus and Matthiola, among the offspring produced 

 by the selfing of an individual heterozygous in G, R and in 

 the white plastid factor which is epistatic to cream, we find the 

 proportion of anthocyanic, i.e. purple and red, to non-anthocyanic, 

 i.e. white and cream, is as 9 : 7. Moreover among the non- 

 anthocyanic, the proportion of whites and creams carrying G 

 to those carrying i2 is as 1 : 1. 



Similarly in Antirrhinum, among the offspring from the 

 selfing of an individual heterozygous in the yellow chromogen 



* Eeports to the Evolution Committee of the Eoyal Society, i — iv. 



