58 MendeVs Experiments 



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 

 expression 



A 4- 2Aa + a 



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 

 equality of fertility in all plants in all generations be 

 assumed, and if, furthermore, each hybrid forms seed of 

 which one-half yields hybrids again, while the other half 

 is constant to both characters in equal proportions, the 

 ratio of numbers for the offspring in each generation is 

 seen by the following summary, in which A and a denote 

 again the two parental characters, and A a the hybrid 

 forms. For brevity's sake it may be assumed that each 

 plant in each generation furnishes only 4 seeds. 



RATIOS. 



A : Aa : a 



1:2:1 

 3:2:3 



7:2:7 

 15 : 2 : 15 

 31 : 2 : 31 

 -l : 2 : 2 n -l 



