Variation and Heredity 483 



forms were found in the hybrid generation, and in these 

 cases reciprocal crosses gave in the F! generation plants 

 entirely alike. 



A summary of the results of the F 2 generation is of 

 special interest. Upon planting the seed of the F x genera- 

 tion there resulted, in the first case, 258 individuals; 

 and these yielded in the F 2 generation 8023 seeds, of which 

 6022 were yellow and 2001 green. In other words, the 

 relation of yellow to green was 3.01 : 1. Where color in 

 the seed coats was a contrasting character there were 929 

 plants in the F 2 generation, of which 705 produced colored 

 seed coats, correlated also with color of blossoms; and 

 224 produced white seed coats, correlated with white 

 flowers. In this instance the proportion was 3.15 : 1. In 

 the third case, there were in the F 2 generation 1064 plants, 

 of which 787 were tall and 277 dwarf, or a ratio of 2.8 : 1. 



In each case one fourth of the individuals, showing the 

 recessive character, breed true in all subsequent generations, 

 that is, in F 3 , F 4 , etc. In analogous manner one fourth of 

 the whole number of F 2 individuals (one third of the ap- 

 parent dominants) breed true as dominants. The re- 

 mainder, one half, are hybrid dominants and break up in 

 the F 3 generation exactly as did the whole number in the 

 F 2 generation. This method pertains through successive 

 generations. It is therefore apparent that the F 2 

 generation may be represented thus: D + 2 D(R) + R, 

 in which D represents dominants, R recessives, and D(R) 

 hybrid or impure dominants, in which only the dominant 

 character is evident. The latter are here indistinguishable 

 from dominants, except as they show segregation in the 

 next generation. 



