258 Genetical Studies in Moths 



To sum up, as in size so in ground colour, markings, etc. both sexes, 

 when due cognisance is taken of their fluctuating variation, and that of 

 the parental forms, are clearly intermediate. But in spite of this I have 

 not the slightest doubt that if captured wild about 80 "/o would be 

 regarded as autumnata and 20 °/^ as filigrammaria simply because, on 

 the one hand, autumnata in its local races presents great variability in 

 its banding, whilst on the other, filigrammaria nearly always appears in 

 a heavily marked banded guise. 



Genitalia. 



The parent forms are too nearly alike (more particularly in the 

 females) in this respect for great differences to be seen in the ^i insects. 

 Perhaps in the males the octavals are nearer than in autumnata and 

 without doubt there are more bristles on the cristae. 



Fertility of the Imagines. 



In accordance with one's expectation in dealing with hybrids between 

 parents so closely allied physiologically both sexes of the F^ insects were 

 fully fertile either when paired inter se or crossed back on 0. autumnata 

 or 0. filigrammaria. All of the possible matings were made, and 

 all of the ova deposited were fertile to the extent of 100 %• From 

 these the F^, F^ ^ y. filigrammaria %, filigrammaria cT x -^i ?> autum- 

 nata (^ y~F^% lots were reared, those of the Fi (^ x autumnata % being 

 discarded owing to lack of cage room. 



Like their parents the larvae of all these crosses were offered haw- 

 thorn, and like their parents they accepted it and fed up with trifling 

 loss. 



The F^ generation. 



The ova from the pairing F^ ^ and F^ $ hibernated as such and com- 

 menced to hatch just prior to autumnata (March 10, 1918). As in the 

 Fy generation, the imagines obtained appeared so as to overlap the 

 periods of autumnata . and filigrarnmaria and thus accompanied their 

 relatives in a new Fi lot reared alongside them. 



Of this generation very little can be said except that in every charac- 

 teristic, size, relative sizes of male and female ( $ size = 89*8 °/^ ,^), wing 

 markings, and so on they were like the ^i brood from which they were 

 bred ; they were intermediate to the two pure species. In no way was 

 segregation in F^ gametogenesis, and subsequent recombination in the 

 F^ zygotes indicated by the reappearance of grandparental characters. 

 In size this feature was displayed to a marked degree as we shall see 



