V] 



Colours of Sweet Peas 



91 



such an epistatlc factor whose property is to make the 

 colour purple, just as the factor B, in the mouse, makes the 

 coat colour black. F^ was therefore purple, and /% con- 

 sisted of 27 purples : 9 reds : 28 whites, as shown below. 

 The factor which determines the colour to be purple is 

 represented as B, the blue factor. 



The diagram (Fig. 17) exhibits in a tabular form the 

 composition of the various 7% plants. The distribution of the 



63 :i 



67:7 



57:7 



15:49 63:1 



57:7 



57:7 



15:49 



Fig. 17. The F^ family from the cross white Emily Henderson Sweet 

 Pea, long pollen X white ditto, round pollen. The 27 cross-hatched 

 squares represent purple plants, all containing B. The 9 single- 

 hatched squares without B are the reds. The 27 squares lacking 

 either C, or R, or both, are all whites of various compositions. The 

 numbers at the foot show the ratio of long to round pollens in the 

 types of individuals represented in the columns above. 



