246 Genetical Studies in Moths 



III. Breeding Experiments. 



(a.) Inheritance of Subspecific Characters and of those characterising 



the Local Races. 



In any enquiry directed towards elucidating the evolution of sub- 

 species and Ipcal races nothing is more important than to determine 

 whether such differences as they present are ontogenetic in character, 

 i.e. developed anew in each generation in response to their own peculiar 

 environmental influences or not. 



The first experiment I initiated along these lines was conducted 

 with the subspecies Oporabia filigrammaria. I obtained ova of this 

 form from wild parents captured at an elevation of 1500 feet on one of 

 the Lancashire moors not far from Burnley. These ova were wintered 

 almost at sea level at Middlesbrough, North Yorkshire. As they hatched 

 the resulting larvae were placed on birch, alder and other foods proper 

 to 0. autumnata. Without exception they accepted these, to them, 

 unusual foods and fed up speedily and healthily, the pupae emerging 

 toward the end of August and the beginning of September just when 

 their relatives would be coming out amongst their native heather. Not 

 a single sign of departure from their own racial characters in the 

 direction of those of 0. autumnata was manifested either in larval 

 colouration, imaginal size, wing markings or in other features. The race 

 was inbred and kept going under similar conditions for five successive 

 seasons and the insects bred each year carefully scrutinised for any 

 possible development of autumnata characters ; never at any time was 

 any hint of deviation from their own normal state given. The experi- 

 ment was repeated, only in this case the larvae from wild moorland 

 females were reared at an elevation of three hundred feet in North 

 Durham, in a district not only producing autumnata but also a race of 

 filigrammaria of characteristic type ; again no autumnata characters 

 appeared nor were there signs of passage to the local filigrammaria 

 form. Obviously from these experiments only one conclusion can be 

 drawn and that is that the subspecific and racial characters in 0. fili- 

 grammaria are germinally fixed. 



Here it is well to remark that never at any point in the half dozen 

 years of inbreeding that this experiment involved were any traces of 

 diminution in vigour displayed; inbreeding with this species \ unlike 



^ And the same held true of birchwood 0. autumnata when inbred for a similar period. 



