178 ANIMAL LIFE AND HUMAN PROGRESS 



Then the original cross means the union of a gamete 

 (AA X A 2 ) containing all three factors with one (aa 1 a 2 ) that 



id 



i i i 



i > 



< 

 < 



contains none of them. The first cross contains a single dose 

 of each of the three factors and is, on hypothesis, exactly inter- 

 mediate in size between the two parents. Such an animal, 



