318 THE entomologist's record. 



emergence. I have had a precisely similar experience with 

 Selenia ilhistraria. Moths of the spring brood captured at 

 large in Chattenden, have given me in the same brood (i) 

 rapidly feeding larvae which have emerged in July (as early as 

 the nth) as the summer form, and (2) slow feeding larvae which 

 have produced in April of the next year the dark winter form. 

 I have also bred the dark winter form after an average temper- 

 ature in my greenhouse of 48" for the winter, again proving 

 that exposure to, or protection from cold has nothing to do 

 with the coloration. But, whilst considering the seasonally 

 dimorphic species Selenia ilhistraria and 5. illunaria, I cannot 

 help remembering how much their coloration must be due to 

 protective resemblance, and as the spring broods of these 

 species hang, wings downward, they can hardly be detected 

 from the dry withered leaves on the plants they respectively 

 frequent. Their environment is so different in the summer 

 months, that it appears to me, quite sufficient to account for 

 the difference in colour of the two broods. 



To show how close is the connection between heredity and 

 the coloration of seasonal dimorphic forms, and the influence 

 that the former undoubtedly has on the latter, I will quote 

 some of Mr. Merriiield's conclusions with which I am in almost 

 perfect accord. That gentleman writes with regard to 

 "heredity" and "seasonal double-brooded species": — " (i). 

 In such a species a young individual may have, and often has, 

 a constitutional capacity for developing into either type, 

 according to external circumstances. (2). It seems probable, 

 that there is, from the beginning of the existence of the 

 individual, a tendency, which may be very strong or very slight, 

 to develop in the direction of one of the two types. (3). If 

 there is no such innate tendency in an individual it can be 

 imparted by external influences during the early part of its 

 existence. (4). Where the tendency exists, it varies in strength 

 in different individuals. In the case of some species, or some 

 broods or individuals of some species, the tendency from the 

 beginning is so strong that it cannot be overcome by any 

 external influences. (5). In other cases the tendency can be 

 overcome and converted into the opposite one, or turned more 

 or less in the direction of it, by such influences. The decision 

 as to the type to be assumed is come to before the termination 

 of the growth of the larva, and this decision may be completely 

 controlled in some cases by external influences applied before 

 that period. For example, in 1887, by keeping the insect in 



