296 THE entomologist's record. 



suppose that the temperature had really very little to do with 

 the actual result, and that one might get as many results, and 

 draw as many separate inferences, as one chose to make 

 different experiments. If Mr. Merriiield's last inference be 

 correct, it should be capable of proof by any competent and 

 careful entomologist, who ought to be able, by dividing a batch 

 of pupae into two separate lots, and by treating them in the 

 way Mr. Merrifield suggests, to obtain two sets of moths of 

 different coloration, by subjecting them, just before emergence, 

 to a high and low temperature respectively. But this is 

 impossible, as collectors know who breed lepidoptera in 

 large numbers and force their pupae ; and I can only repeat, 

 that I believe the larval stage is the vital one, and that experi- 

 ments on pupae can give but negative results. Last winter, in 

 January, I forced at a very high temperature a large number of 

 specimens of Mamcstra persicaricB and Macroglossa fticiforinis ; 

 these were exceptionally dark, but those I left in a cool green- 

 house, and which emerged much later in the year at a lower 

 temperature, were equally dark, and I can only infer that the 

 temperature to which the pupae were exposed, did not affect 

 the coloration, but that whatever tended to make these two 

 broods darker than usual, must have affected the larvae before 

 they entered the pupal stage ; and yet this is in direct opposi- 

 tion to Mr. Merriiield's inference, that the subjection of pupae 

 to a high temperature just before emergence, produces a pale 

 coloration, and I can only assume that the variation in Mr. 

 Merrifield's experiment was produced independently of the 

 temperature, and was the result of some previous condition of 

 the larval stage, or a simple result of heredity, or some other 

 incidental circumstance not yet taken into account, and, in the 

 case of Sehnia illustraria, which Mr. Merrifield has been inter- 

 breeding for several years for other experiments, the result 

 obtained may be, in part, due to a weakened (diseased ?) con- 

 dition of the larvae, brought about by interbreeding ; but this 

 phase of the subject is dealt with in another paragraph. 



In close connection with heredity are the development of 

 dimorphic seasonal forms, when one or other of the forms has 

 melanochroic tendencies, and the inquiry as to how these 

 forms may possibly be produced. With regard to " seasonal 

 forms" Mr. Cockerell writes: — ^' Papilio ajax, spring form 

 telanionides, Feld., and summer form inarcelliis, Bd. Pieris 

 protodice, spring form vernalis, Edw., is smaller and darker 

 than the summer form. P. oleracea, summer form often larger, 



