ANTHOCYANINS AND GENETICS 171 



CCmm yellow. 



Ccinin pale yellow. 



ccMM white. 



ccMm white. 



ccmm white. 



It was also found that a certain two white individuals crossed 

 together gave coloured (anthocyanin) F x , as in Matthiola and Lathyrus. 

 Hence the factors for anthocyanin production can be separated into two 

 components, of which one is M, and the other is not represented in the 

 above scheme. Absence of colour may be due to loss of either of these 

 components, or to loss of the yellow pigment. 



Nicotiana. Inheritance of anthocyanin in species-crosses. Lock 

 (532), Haig Thomas (594). 



Oenothera. Since Oenothera is a plant which forms anthocyanin 

 in its stems, petioles, buds, etc., the complex inheritance of characters 

 among the numerous strains which have been employed experimentally 

 involves also the inheritance of this pigment. Mention will only be 

 made of one or two cases in which anthocyanin pigmentation has been 

 considered an important character. 



The first case to be dealt with is that introduced by Gates (539, 

 555, 573), and which concerns the appearance of 0. rubricalyx. This 

 variant was found among the offspring of self-fertilised rubrinervis 

 plants, the latter being characterised by having the calyx of the buds 

 streaked with anthocyanin, whereas 0. rubricalyx has a completely 

 red calyx. The segregation of the offspring from self-fertilised rubri- 

 calyx plants in two generations, into rubricalyx and rubrinervis, led 

 Gates to consider the case purely Mendelian. The original rubricalyx 

 plant was regarded as a heterozygote which has acquired a dominant 

 Mendelian character, the character being purely quantitative, i.e. as 

 causing an increased formation of anthocyanin. 



In a later paper (606) Gates again states that the red pigmentation 

 character, R (which originated by a mutation and distinguishes rubri- 

 calyx from rubrinervis), is more or less completely dominant in F, from 

 the cross grandiflora x rubricalyx and its reciprocal. In F 2 , 3 : 1 ratios 

 were obtained, and also ratios of 5 : 1 and 10 : 1 as well as 3 : 1. Gates 

 has no satisfactory explanation of these facts. 



Shull (609) makes further experiments on rubricalyx by selfing 

 this strain and crossing it with rubrinervis and with Lamarckiana ; 

 he obtains what he calls a series of negative correlations in the distri- 

 bution of the red pigment, the pigmented buds of rubricalyx being 



