146 



Experimental Zoology 



When Blanc des Alpes are crossed with Jaune Var, all the off- 

 spring have yellow cocoons. The next generation gave yellow 

 and white cocoons with none intermediate; the proportion of 

 yellow averaged in fifteen lots 75.2. Here there seems to be 

 an approach to one fourth that strongly suggests the Mendelian 

 ratio. In other cases, however, an average of 49.3 per cent was 

 obtained. The evidence here is opposed to this interpretation, 

 unless one of the races itself had a latent character that did not 

 appear until the second generation. 



(8) When two crossed races give a separation in equal parts 

 of the two characters, the following generations give equally 

 again the separation of the two characters without its being pos- 

 sible to realize their fusion in a single individual. 



For example, two types were crossed, each having striped 

 worms and yellow cocoons. The offspring gave four classes : — 



In another case the female belonged to a race with white worms 

 and cocoons, the male striped and yellow cocoons. The crosses 

 were : — 



Seven other combinations are given, but until some principle 

 running through these cases can be formulated it is needless to 

 recount all the results here. It is true that Coutagne attempts 

 to show that the rule in subsequent generations is such that the 

 inheritance of the contrasting characters follow the sequence of 



