HEREDITY 



characters were involved, Fj would be un- 

 changed, all 6 inches, yet the F 2 classes would 

 be more numerous, viz., 4, 5, 6, 7, and 8 inches, 

 and their relative frequencies as shown by the 

 height of the columns in Fig. 47, middle left, 1, 4, 

 6, 4, 1. The grandparental states would now re- 

 appear in i/s f the F 2 young, while % would be 

 intermediate. It is certain, however, that in rab- 

 bits the grandparental conditions, if they re- 

 appear at all, do not reappear with any such 

 frequency as this. 



If three independent size-factors were in- 

 volved in the cross, the F 1 individuals should all 

 fall in the same middle group, as before, viz. 

 6 inches, but the F 2 classes should number 

 seven, and their relative frequencies would 

 be as shown in Fig. 47, top left. For 4 independ- 

 ent size-factors, the F 2 classes would be more 

 numerous still, viz., 9 (Fig. 47, right), and the 

 extreme ear-size of either grandparent would 

 be expected to reappear in only one out of 256 

 offspring, while considerably more than half 

 of them would fall within the closely inter- 

 mediate classes included between 5^ and 6 l /o 

 inches, the three middle classes of the diagram. 



136 



