8G Mr. Merrifield's incidental ohserrations 



treatment which seems in all three species to produce a 

 generally warmer and yellower hue, with a less amount 

 of dark spots. This is to be noticed in illunaria. In 

 the illustraria bred by me this effect is masked by the 

 circumstance that the races I have belong mostly to 

 two very different types — a warmly-tinted one with few 

 markings, and a duskier one with conspicuous darker 

 bands and patches. In autiimnaria the difference is 

 very conspicuous, as will be seen by comparing the 

 forced brood, of which 26 have been preserved out of 29 

 bred (3 having been sacrificed for eggs) with the 

 sleeved brood, of which 24 have been preserved out of 

 25 bred ; and with the intermediate " bottled " brood : 

 — (1), the general colouring of the forced is warmer; 

 [ (2), in all the spots of the forced contrast less strongly 

 with the ground colour; (3), generally, if not always, 

 the spots and marks of the forced ones are less dusky, 

 and (4) not nearly so dark ; (5), nearly all the males, 

 and all but one of the females, have fewer spots than 

 the corresponding sexes in the sleeved : on the under 

 side the differences are more strongly marked.] The 

 general result is that of the 26 forced there is only one 

 that comes up to the general standard of the 24 sleeved 

 in abundance and darkness of spotting and other marks, 

 and there are only 3 of the sleeved which in lightness 

 of spots and marks approach the general hue and 

 appearance of the 26 forced. 



[Autumnaria. — The difference in appearance between 

 the forced and the sleeved being so marked, I give in 

 some detail the facts, which appear to indicate that in 

 this case the conditions to which the larvffi were sub- 

 jected may have had much to do with the very striking- 

 difference in the moths. One of two conclusions at all 

 events seems almost to follow from the experiments, r?>., 

 that the larval period was the critical one, or that the 

 colour of the perfect insect in this single-brooded and 

 summer-pupating species can be affected by exposing 

 the pupae to a very moderate difference of temperature. 



The eggs were kindly given to me by Dr. Chapman. 

 There were 4 batches from (1), dark full-sized parents 

 of British origin ; (2), large-sized pale parents of un- 

 known origin ; (3), a cross between male (1) and female 

 (2) ; and (4), a cross between male (2) and female [D. 

 I took 10 from each of the 4 batches to make a batch of 



