122 Experiments with Primula sinensis 



Taking the red- and light-stemmed classes together, the self-colours 

 are 413, the flakes 135, numbers which suggest that the flaked 

 condition is a simple recessive, the expectation in such a case being 

 411 colours : 137 flakes. The distribution of the self-colours and flakes 

 among the red and light stems is however irregular, especially in the 

 palmate plants of 62/10. 



"Ivy-leaf" x Dominant white. Up to the present time F^b have 

 been raised from only one cross of this kind, that of ("Ivy-leaf" x "Prim- 

 rose Queen "). The F^ is noteworthy for two reasons : (1) no self-colours 

 are obtained, all the coloured offspring being flaked ; and (2) no pale- 

 pinks occur. The numbers are : 



Red stems Light steins 



White Magenta flakes White Flakes 



Palmate leaves 93 26 36 — 



Ivy leaves ... 43 4 8 — 



The flakes grade from fully-flaked to small and sparse flakes of 

 colour. It may be noticed that the young flower-buds of the flaked 

 forms are quite strongly tinged, even though the flaking may prove to 

 be sparse. The great excess of whites, as compared with flakes, among 

 the Ivy-leaved offspring is probably of no great significance, as it 

 may well be due to the reduced corollas of the Ivy-leaves. The 

 plants with light stems were carefully examined in view of the results 

 obtained from the cross of ("Ivy-leaf " x "Crimson King"), and no trace 

 of flaking was observed in any. It may be remarked however that 

 both "Primrose Queen" and "Ivy-leaf" carry the factor which partially 

 suppresses flower-colour, and even the full colours are very light. 



" Ivy-leaf" x " Snowdrift." The F^ from this cross has definite, 

 though faint, colour in the flowers. In the F^, plants with definitely 

 coloured flowers form approximately 9 in every 16 plants, the observed 

 numbers being 144 definitely coloured in a total of 273 plants 

 (t6 *^f ^'^^ — 1^3'5). The plants recorded as definitely coloured were, 

 so far as could be judged, self-colours ; in one at least of the remainder 

 the "ghost" of a coloured flake was recognized. In this cross, again, both 

 parents bring in the factor which partially suppresses flower-colour. 



Discussion of the " Ivy -leaf " crosses. The appearance of the "Ivy- 

 leaf" plants and the characters of the Fi obtained from their crosses 

 with colours, led me to look upon " Ivy-leaf" as a recessive white ; but 

 the result of the crosses with " Crimson King " suggests that this view 

 will need revision, and that the plant may really possess the pale-pink 



