230 THE entomologist's recoed. 



has much to do with the colouring of the perfect insect " 

 (p. 82). Mr. Merrifield also writes: — "As to the causes of 

 variation in colour, markings and shape, the inquiry is a more 

 complicated one, of course embracing the pupal stage, though 

 I am inclined to think, for reasons I will give, that it should 

 by no means be confined to that stage" (p. 84). The first 

 observation relates to Ennouios autumnaria, which were bred in 

 the " wet " and cold summer of 1888. There were three sets : 

 one kept out of doors and exposed to wet and cold ; a second 

 kept indoors in a " drier " and warmer atmosphere ; whilst a 

 third was kept indoors but " bottled." Mr. Merrifield, treating 

 his as " temperature " experiments, supposed the differences in 

 these sets to be due to the difference in temperature. I con- 

 sider the difference due to the difference of the "wet" and 

 moist conditions to which the larvae were subjected. Mr. 

 Merrifield writes : — " In autumnaria, the difference (between 

 these first two sets) is most marked and very conspicuous. 

 .... Generally, if not always, the spots and marks of the 

 forced ones are less dusky, and not nearly so dark ; nearly all 

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

 the corresponding sexes in the sleeved ; on the underside^ 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 in dark- 

 ness 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" (p. 86). That 

 is, those that were exposed to the wet season of 1888 as larvae, 

 were much darker than those bred indoors and protected from 

 these conditions. Mr. Merrifield, regarding this experiment, 

 goes on to say ; — "The difference in appearance between the 

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

 facts, which appear to indicate that, in this case, the conditions 

 to which the larvae were subjected 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, viz., 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." Mr. 



^ This tends to prove my previous statement, as to looking for variation on the 

 underside of butterflies. This moth rests like a buttertiy willi its wings drawn up 

 over its body. — J.W.T. 



