ANTHOCYANINS AND GENETICS 185 



effect; thus LlDD(d) is pale magenta, and LLDD(d) is intermediate 

 magenta. 



A second heterozygcms form in Antirrhinum is also interesting. 

 Individuals heterozygous for the striping factor have magenta stripes 

 on a tinged ground, individuals homozygous for the striping factor, 

 magenta stripes on an ivory ground (Wheldale, 535). 



Mirabilis Jalapa is of special interest in this connection since it is 

 a species- in which individuals heterozygous for any of the factors so 

 far identified have a heterozygous form, and this applies, not only to 

 the factor converting yellow chromogen into anthocyanin, but also 

 to the factor for the presence of chromogen (Marryat, 533). 



In Indian cotton, individuals heterozygous for the factor which 

 produces anthocyanin in the flower have this pigment diffused through 

 part only of the petal, whereas homozygotes have anthocyanin through- 

 out the flower (Leake, 561). 



In some strains of Phaseolus, plants which are heterozygous for 

 mottling with anthocyanin in the testa have mottled seeds, whereas 

 homozygotes in this factor have self-coloured purple seeds (Shull, 521). 

 It is at the same time well known that homozygous true-breeding 

 mottled races do exist, and Emerson has attempted to explain this 

 anomaly by postulating two factors concerned in mottling. 



COLOUR FACTORS IN REDUPLICATION SERIES 



It was first observed by Bateson & Pimnett (549, 550) that in the 

 case of certain factors, which for the moment we may call A and B, 

 the nature of the F 2 generation varies according to whether A and B 

 are carried into the Fj heterozygote by the same gamete or by different 

 gametes. Thus if the heterozygote AaBb is formed from the gametes 

 AB and ab, then the gametes of the heterozygote are not formed in 

 the proportion 



1AB : lAb : laB : lab, 



but may be formed in the following proportions: 



SAB : Ab : aB 



TAB : Ab : aB 



15AB : Ab : aB 



3ab 

 Tab 

 15ab, etc. 



If. on the other hand, the heterozygote is formed from the gametes 

 Ab and aB, the gametes from the heterozygote so derived are produced 

 in some one of the following proportions : 



