98 Experiments with Primula sinensis 



mentary factor (C) is common both to the factor for full colour {R) and 

 to that for faint colour {Q), so that the combination CR gives full 

 colour^, and the combination GQ gives faint colour in the collar. The 

 constitution of the hybrid would then be Gc Rr Qq, and the F^ would 

 consist of the three types in the proportion of 36 full : 9 faint : 19 green, 

 or, in a total of 87 plants, 48-94 : 12-23 : 25-83. 



The only matings of the " Ivy-leaf" from which F^s have as yet been 

 obtained, are its crosses with " Snowdrift " and with full-coloured forms. 

 The ^2 from the cross with "Snowdrift" is chiefly interesting in con- 

 nexion with the partial suppression of stem -colours, and is considered 

 more fully under that head (p. 101). Unlike the majority of the 

 experiments on stem-colour, in which the observed results agree witli 

 the expectation very fairly closely, there is a great dearth of light- 

 stemmed offspring in the F^'s from the crosses between "Ivy-leaf" and 

 plants with fully coloured stems. The deficiency is most marked in 

 the class in which the light colour is combined with the "Ivy-leaf" 

 habit, but is also apparent, though in less degree, in the light-stemmed 

 plants of the normal kind. There do not however appear to be 

 sufficient grounds for supposing that any novel phenomenon occurs 

 in these cases. 



Table shovnng the results of experiments in regard to stem-colour. 



I. Red stem (C EF Q) x Green stem {c rF q) 



Fi selfed 1 family Red 51 Light 33 



Colour in petioles 13 Green 25 



Red 49 



38 

 Totals ... "lOO 71 



Expectation (9 : 7) 96-2 74-8 



11. Faint colour in petioles (C Q) x Green stem (C q) 



Fi selfed 9 families Faint colour 366 No colour seen 130 



Expectation (3 : 1) 372-0 124-0 



III. Red stem (G RF Q) x Faint colour (C rF Q) 



Fi selfed 11 families Red stem 384 Faint colour 120 



Expectation (3:1) 378-0 126-0 



» Strictly speaking this combination gives the parti-coloured type " Sirdar," but as no 

 "Sirdars" appear in this F-y we are not here concerned with the distribution of the 

 full colour. 



