82 



THEORY OF EVOLUTION 



tliat differ from each other markedly in color 

 patterns (fig. 43). When any two individuals 

 of these races are crossed they give, as Nahours 

 has shown, in F^. a JMendelian ratio of 1: 2: 1. 

 It is ohvioiis, therefore, that there are here at 

 least nine characters, any two of which he- 

 have as a ^lendelian pair. Tliese races have 



Fio. V.i. FiJiir wild ty])('.s of Paratettix ill upper line with 

 tiii'ee li\'brids lielnw. 



