178 ANTHOCYANINS AND GENETICS 



whites. Keeble & Pellew give evidence for regarding ' Snow King,' 

 which is a red-stemmed variety with white flowers, as a recessive white. 

 Crosses between various plants of ' Snow King ' and fully coloured 

 varieties showed that ' Snow King ' may be homo- or heterozygous for 

 the dominant white factor, or may be entirely without it. 



'Snow King' x 'Snow Drift' gave magenta Fj. Hence these two 

 white-flowered varieties can give colour. 



Reseda odorata. Compton (569) has shown that orange-red colour 

 (anthocyanin) in the pollen is dominant to bright yellow ; self-fertilised 

 heterozygotes throw about three reds to one yellow. 



Salvia Horminum. Saunders (487) has worked with the type and 

 varieties of this species. The type has violet flowers, and the bracts 

 of the inflorescence are also coloured violet. A red variety was used 

 in which the flowers and bracts were red. Both pigments are antho- 

 cyanins. Loss of pigment gives an albino from w y hich anthocyanin 

 is completely absent. 



The inheritance can be represented by the following scheme: 



BR .purple. 



R red. 



B white. 



white. 



Senecio vulgaris. Trow (589) has published results of crossing a 

 number of elementary species. It was found that red colour, antho- 

 cyanin, in the stem is dominant in some elementary species. It is 

 suggested that one factor is involved, or possibly two. 



Silene Armeria. Colour in flower dominant to albinism (de Vries, 

 498). 



Sclanum tuberosum. East (538) has published some results. He 

 states that presence of anthocyaniu in the stem is dominant to its 

 absence, and segregates on Mendelian lines. Purple in the flower is 

 probably dominant to its absence. The colour of the tubers is either red 

 or purple, and purple is dominant to red. 



Salaman (544) has published more extensive results. Black tubers 

 of the variety, 'Congo,' have purple anthocyanin in the skin. The 

 red-tubered variety has red anthocyanin. White tubers have no antho- 

 cyanin. Two factors are required for colour (red), and a third dominant 

 factor gives purple. S. eiulerosum has a dominant white factor inhi- 

 biting the purple. 



In the flowers all pigment is anthocyanin. Heliotrope colour is 

 due to two factors, and purple to a third factor. In varieties of 



