H. Onslow 



295 



Melanic x Melanic. 



Imagines 

 >■ 



Melanic 



Type 



Bred by 



E. Harris (1905) 

 G. Porritt (1905)' 

 H. Onslow (1917) 



Male 



34 



? 



3 



Female 



34 

 ? 



1 



Totals 



68 



20 



4 



Male 



Female Totals 



Total 



92 



Melanic (heterozygous for type) x Melanic (heterozygous for type). 



Imagines 



Melanic (heterozygous for type) x Type. 



Ima^nps 



Melanic 



Type 



It will be observed from these tables that in matings of type x type, 

 with a single exception which is probably an error, nothing but type 

 is given, and similarly, in matings of melanic x melanic, when one 

 parent is homozygous, nothing but melanic is given. 



In the families bred from melanic parents, both of which are hetero- 

 zygous for type, the ratio of melanic to type insects is very nearly 

 3 : 1, as would be expected if melanism were dominant. 



When a heterozygous melanic is crossed with a type insect, the ratio of 

 type to melanic should be one of equality, but as will be seen from the 

 figures in the last table, which includes crosses made both ways, i.e. the 



1 Porritt, G. See J. W. Tutt, British Lepidoptera, Vol. v. p. 59. 

 Pearce, W. G., loc. cit. (see p. 294). 



