80 Mr. Merrifield's incidental observations 



28th January. They showed unmistakable signs of 

 deterioration, being for the first time smaller than their 

 parents, and being poorer in colouring. All the eggs 

 laid were sterile except one batch, of which 179 turned 

 red. Thinking that the deterioration was probably, in 

 part at least, attributable to the unnatural conditions in 

 which they had been bred, which included continued 

 forcing, and a food supply of winter leaves of evergreen- 

 honeysuckle and rose, I decided to keep back the eggs, 

 and consequently placed them out-of-doors from the 

 beginning of February to the 14th April, a period during 

 which the weather was cold, with much frost, and then 

 forced them. On the 17th April they began to change 

 colour, and in a few days all had turned black, and the 

 young larvae could be plainly seen through the shells of the 

 eggs, but not one hatched. This experiment seems to 

 show that long exposure to a winter temperature is not 

 directly fatal to the eggs of this species, which under 

 ordinary natural conditions are exposed only to a spring 

 or summer temperature, and suggests the possibility 

 that under changes of climate the insect, which now 

 hibernates as a pupa, might come to hibernate as an 

 egg. It also appears to indicate that the formation of 

 the larva in the egg of this species is not gradual, but 

 awaits the proper conditions, the chief among them 

 being a sufliciently high temperature, and is then rapid. 

 In this deferred development of the latest stage, the egg 

 appears to bear some resemblance to the pupa, the 

 development of which is referred to later on. 



Illunaria, spring emergence, male larger than female. — 

 It will perhaps be remembered that last year attention 

 was called to the fact that though the female of illunaria 

 in the summer emergence exceeds the male in wing- 

 expansion, there was some reason to think that the 

 reverse was true of the spring emergence. The latter 

 opinion is confirmed by measurements since made of 

 a great number of moths of the spring emergence. [In 

 each of three broods, together numbering 86 males and 

 107 females, the average size of the male exceeded that 

 of the female, the excess on the average of the whole 

 being 0.26 mm., the largest male being 51 mm., and 

 the largest female 49.50 mm. This compares with an 

 excess on the part of the female in the summer 

 emergence, — arrived at by measuring seven broods 



