270 Genetical Studies in Moths 



After waiting in vain six weeks for further emergences I unearthed the 

 remainder of the pupae expecting them to be dead, but was astounded 

 to discover that practically every pupa was alive and healthy, and that 

 every one was a male. These were packed as usual in moss and cocoa- 

 nut fibre in air-tight tin boxes and laid aside to be carefully inspected 

 at intervals. No further moths put in their appearance until October, 

 when the rest came out in company with the parent species. 



Description and discussion of the resulting insects are greatly com- 

 plicated by my unfortunate but unavoidable choice of melanic dilutata, 

 which at the time was the sole form of the insect accessible to me. 

 Owing to the blurring effect of the melanism other details are rendered 

 obscure. Very obviously, however, the males are strict intermediates 

 when correct value is attached to every point, whilst just as certainly 

 one would assign the females to pure dilutata. Here then was the first 

 hint of that sex-linkage in inheritance in the genus which I have pursued 

 at some length above. Subsequently, in order to clear away the inde- 

 cision induced by the melanism I have employed ordinary birchwood 

 autumnata and non-melanic Irish dilutata in my later experiments, so 

 that more exact comparison of the hybrid insects with their parents 

 becomes possible. 



In the light of these new broods I find but little to alter in my 

 views; the male remains intermediate no matter what strain of autumnata 

 is involved (and I have now succeeded in introducing all of the races 

 known to me from birch, alder and pine) ; still I must confess that the 

 closeness of the females to pure dilutata is not so decided, for on the 

 clearer non-melanic ground colours autumnata shows some, if varying, 

 influence. 



Full description of all of the imagines reared in the later trials would 

 be impossible, such a wide range of variation is introduced by the con- 

 tinuous or fluctuating variation so prominent in both parent species. 

 Due to this fluctuating variation in the males, one can almost say that 

 a perfect transition exists from pure autumnata to pure dilutata in 

 outward appearance. In spite of this their hybrid nature is at once 

 betrayed to the expert by the peculiar texture of the wing scaling, which 

 in every case compromises between the coarse whity-yellow tone of 

 dilutata and the fine silkiness of autumnata, and gives us a silvery gre}-- 

 ground quite unlike what one encounters elsewhere in the genus, but 

 still recalling that exhibited by several other Larentiad species. One 

 very important point must be singled out for special mention and that 

 is that if the clear, sharply marked birchwood autumnata with the 



