in Hybridisation 349 



distribution of the dominant and recessive characters results 

 in the first generation, resolves itself therefore in all experi- 

 ments into the ratio of 2 : i : i if the dominant character 

 be differentiated according to its significance as a hybrid- 

 character or as a parental one. Since the members of the 

 first generation \F^\ spring directly from the seed of the 

 hybrids \F^\, 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 dominant or the 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 i 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 : i : i 

 into hybrids and constant forms. 



If A be taken as denoting one of the two constant 

 characters, for instance the dominant, a, the recessive, and 

 Aa the hybrid form in which both are conjoined, the ex- 

 pression 



shows the terms in the series for the progeny of the hybrids 

 of two differentiating characters. 



The observation made by Gartner, Kolreuter, and others, 

 that hybrids are inclined to revert to the parental forms, is 

 also confirmed by the experiments described. It is seen 

 that the number of the hybrids which arise from one 

 fertilisation, as compared with the number of forms which 

 become constant, and their progeny from generation to 

 generation, is continually diminishing, but that never- 

 theless they could not entirely disappear. If an average 



