in Hybridisation 57 



number of 100 trial plants. Experiment 5, which shows 

 the greatest departure, was repeated, and then in lieu of 

 the ratio of 60 and 40 that of 65 and 35 resulted. The 

 average ratio of 2 to I appears, therefore, as fixed with 

 certainty. It is therefore demonstrated that, of those forms 

 which possess the dominant character in the first generation, 

 in two-thirds the hybrid character is embodied, while one- 

 third remains constant with the dominant character. 



The ratio of 3 to 1, in accordance with which the 

 distribution of the dominant and recessive characters 

 results in the first generation, resolves itself therefore in 

 all experiments into the ratio of 2 : 1 : 1 if the dominant 

 character be differentiated according to its significance as 

 a hybrid character or a parental one. Since the members 

 of the first generation spring directly from the seed of the 

 hybrids, it is now clear that the hybrids form seeds having 

 one or other of the two differentiating characters, and of 

 these one-half develop again the hybrid form, while the other 

 half yield plants which remain constant and receive the domi- 

 nant or recessive characters [respectively] in equal numbers. 



THE SUBSEQUENT GENERATIONS [BRED] FROM THE HYBRIDS. 



The proportions in which the descendants of the hybrids 

 develop and split up in the first and second generations 

 presumably hold good for all subsequent progeny. Experi- 

 ments 1 and 2 have already been carried through six 

 generations, 3 and 7 through five, and 4, 5, and 6 through 

 four, these experiments being continued from the third 

 generation with a small number of plants, and no departure 

 from the rule has been perceptible. The offspring of the 

 hybrids separated in each generation in the ratio of 2 : 1 : 1 

 into hybrids and constant forms. 



