H. Onslow 



57 



eggs were kept in metal boxes, in which the young larvae were allowed 

 to remain a fortnight. They were then transferred to the ordinary 

 type of glass breeding cylinders. Since the larvae will only eat 

 the tenderest oak leaves, sycamore (Acer pseiidoplatanus) was largely 

 used towards the end of June, when the larvae commence " feeding-up." 

 It is, however, sometimes possible to get a supply of adventitious oak 

 shoots, from trees which have been stripped . some time previously by 

 any small Geometer. The pupae were allowed to remain in the leaf- 

 mould and sand in which they pupated, until the following spring. Over 

 one thousand insects emerged in 1919, and are shown in the following 

 tables. When the type insects used for pairings were not extracted from 

 melanics, they came from wild pupae collected in Buckinghamshire. 



The result of pairing two melanics, at least one of which was homo- 

 zygous, was as follows : 



Melanic x Melanic [DD x I>I) (K)]. 



Imagines 



Family 



'15 C 

 '18 M 



Bred by 



L. W. Newman 

 H. 



Totals 



Total 



193 



The result of pairing two melanics, both of which were heterozygous, 

 was as follows : 



Melanic x Melanic [DE x DJi], 



Imagines 



The percentage of types to melanics is very close to the expected 

 ratio 75 : 25. 



The result of mating homozygous melanics to types should give 

 nothing but melanics. The result was, however, as follows : 



