138 



GENETICS IN RELATION TO AGRICULTURE 



race. In the actual experiment among seven families comprising a total 

 of 440 plants only one produced white grains, but the F 3 generation 

 demonstrated the adequacy of the three-factor analysis. The inter- 



f 



F 



S 5 Q e * <"* !C Sr " 



i- F IS v a B cS 



00 OOOOCDOO 00 O 



t- o XBB^PvfiS^ 



oc4 rt is t> to t- rt "*". "^ 



Fio. 62. Resum6 of ratios found in 142 families in the first five generations following 

 the cross between Bursa bursa-pastoris and B. Heegeri. Each square represents a possible 

 family, the position of a family being determined by the percentage of plants with tri- 

 angular capsules as indicated at the base of the figure. (After Shull.) 



mediate shade of red produced in FI and the varying shades produced in 

 segregation depend on the cumulative effect of the color factors. In- 



