LAWS OF GALTON AND MENDEL 181 



formulated then, his second law, the law of segrega- 

 tion of characters. 



A study of the descendence of this second genera- 

 tion of hybrids reveals curious facts which enable one 

 to make certain forecasts as to the number of indi- 

 viduals each category will contain : the recessives with 

 green seed, on being crossed between themselves, pro- 

 duce recessives only, for an indefinite number of gen- 

 erations ; the dominants give rise to a mixed offspring, 

 one-third pure dominant (so called because they breed 

 true for ever afterwards), and two-thirds impure 

 dominants, which, in the following generations, breed 

 dominants and recessives in the proportion of three 

 to one. 



Mendel's experiments were repeated and their re- 

 sults checked up by many botanists and zoologists. 

 Correns experimenting on peas and corn, Tschermak, 

 De Vries, Bateson and his associates on various plants, 

 Darbishire and Cuenot on mice, Hurst on rabbits, 

 Toyama on silk worms, Davenport on fowls, all con- 

 vinced themselves that Mendel's laws held good in the 

 majority of cases. The result of certain crosses can 

 sometimes be predicted with startling accuracy. 

 Lang crossed two varieties of Helix hortensia or com- 

 mon snail, one with a bandless, the other with a banded 

 shell. All the hybrids of the first generation had a 

 bandless shell (dominant character) ; the following 

 generation gave rise to a mixed offspring, bandless 



