ANTHOCYANINS AND GENETICS 151 



the series crimson, red, orange, yellow and ivory-white: in the latter 

 the type is, as a rule, crimson and gives the series magenta, orange, 

 red, yellow, pale yellow and sometimes cream or white. 



There is another series we may best consider at this point, and that 

 is one in which a particular variety of plastid pigmentation occurs 

 known as 'cream.' The plastids contain an orange-yellow pigment, 

 but only in sufficient quantity to give the petals a cream appearance, 

 and the variety is further characterised by being recessive to white 

 containing colourless plastids. Such a ' cream ' variety is found in the 

 Sweet Pea, Lathyrus odoratus (Bateson, 524) and Matthiola (Saunders, 

 475); in Matthiola the series runs: purple, crimson, terra-cotta, white 

 and cream. The cream may underlie any of the anthocyanin pigments, 

 but it is too pale to affect the resultant colour, and such individuals 

 are indistinguishable from those having anthocyanin on a white ground, 

 except at the 'eye' of the corolla where the cream or white ground, 

 as the case may be, is shown. In Lathyms there is a very great range 

 of colour, and the exact inter-relationships of many varieties are still 

 unknown; the series includes blue, purple, mauve, crimson, pink, 

 salmon, white and cream. In some varieties (Thoday, 547) the under- 

 lying cream modifies the effect of the anthocyanin. Cream plastids 

 are also found in Hyacinthus orientalis in which they produce a fairly 

 deep yellow ; in this species the range of colour is also very great, since 

 it includes several shades of blue, purple, magenta, pink, as well as 

 white arid cream, but, as there have been no systematic breeding experi- 

 ments, their relationships to each other cannot be stated. It is not 

 known whether the cream plastids in varieties of Rosa are of the same 

 nature as those of Lathyrus and Matthiola. 



Finally there is the series which includes a blue variety. Variation 

 to redness when the type is blue or purple is, as we have seen, a common 

 phenomenon, but variation to blueness is much less frequent. In 

 Lathyrus odoratus varieties have appeared which are bluer than the 

 type, 'Purple Invincible,' and the same is true for Phlox Drummondii. 

 In Primula sinensis, true blue- flowered varieties, 'Cambridge' and 

 'Oxford' blues, occur, the type in all probability having had pale 

 magenta flowers (Hill, 577); so also from the original Cineraria with 

 flowers of a pale magenta, blue-flowered varieties have arisen, though 

 probably under the influence of species-crossing. A striking instance 

 of a blue variation from a scarlet is the variety, coerulea, of Anagallis 

 arcensis (Scarlet Pimpernel) 1 . 



1 Kajanus (579) states that blue is recessive to red in Trifolium (Clover). 



