124 Experiments ivith Primula sinensis 



separation of the flaked and distributed forms of the same factor, and 

 not in a segregation of the factors for flaked and for self-colour from 

 their respective " absences." 



On this hypothesis the results of the crosses with "Primrose Queen" 

 may be explained as in the subjoined scheme, where 



X, Y, the colour factors in the distributed condition ; 

 X', Y', the colour factors in the flaked condition ; 

 R, inhibition. 



Assuming the constitution of the parents to be " Snowdrift" = xYr ; 

 " Primrose Queen " = XyR ; " Ivy-leaf" = XY'r ; then 



"Snowdrift" x "Primrose Queen," Fi = XxYi/Rr, 



F.2 should give 9 se//-coloured : ho white 



Observed 13 „ : 66' „ 



Calculated ll'l „ : 67'9 „ 



"Ivy-leaf" x " Primrose Queen," F, = XXY'yRr, 



F„ should give 3 flakes : 13 whites 



Observed 26 „ : 93' 



Calculated 22-3 „ : 96-7 „ 



"Ivy-leaf" x "Snowdrift," F, = XxYY'rr, 



F^ should give 9 self-coloured : 7 flaked and white 

 Observed 144 „ : 129 



Calculated 153-5 „ : 110-4. 



The conception of the relation between the flaked and self-colour 

 characters set forth above does not pretend to do more than provide a 

 means by which the results of the experiments may be described. It 

 brings us no nearer the solution of the problem as to how the flaked 

 distribution is brought about, nor is it intended as implying that the 

 colour-factors themselves may not be the same in the flakes as in the 

 self-colours, the mode of distribution of the colour being determined 

 independently. 



Gametic Coupling and Repulsion. 



Evidence has been obtained of the existence of (1) a repulsion 

 between the factor for the structural character of short-style and certain 

 factors affecting the colour of the flower, and (2) of a partial coupling 

 between two colour factors. 



' The numbers given are those obtained in the red-stemmed class only, since the 

 distinction between coloured and white green-stemmed plants is not critical. 



