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chrysalis. The butterflies which appear in spring, have spent 

 the wiuter in the chrysalis state; these lay eggs in June, which 

 pass through all the stages of egg, caterpillar, and chrysalis 

 states in a few weeks, appearing as perfect insects in the summer, 

 but in the form of the summer emergence. Now Dr. Weisman 

 has found that if the chrysalis, which in ordinary course would 

 produce the summer emergence form, are prevented from develop- 

 ing, by being placed for a sufficient time in a cold place, say in 

 an ice safe, they appear with the coloration of those of the usual 

 spring emergence, or, iu other words, in nature, A produces B, 

 B A, and so on, but when thus retarded, A produces A entirely 

 skipping B. 



The hypothesis of the learned Doctor was that both forms 

 were descended from Pieris bryonice, an Alpine single brooded 

 form which perhaps existed over Europe during the glacial 

 period, this species is very much darker than even the British 

 spring form of the insect; that, as the climate became ameliorated, 

 the insect gradually acquired the double brooded habit, and at 

 the same time became seasonably Dimorphic, or, as I term it, 

 Horeomorphic ; he then proceeded to test the truth of this hy- 

 pothesis, by forcing the insect back to its old condition of single 

 broodedness, and with the result that the form, that of the 

 summer emergence, least like Pieria brijonicc, was eliminated. 

 All this is well set forth iu Mr. Raphael Meldolas' translation 

 of the Doctor's work on this very interesting subject. 



Some of the British species of Ephijra and Ennomos amongst 

 the moths, and of Lycceim and Polyommatus amongst the butter- 

 flies are horeomorphic, 



Ennomas illustraria is Horeomorphic, and it has been observed 

 that out of one brood some of them will appear iu the summer in 

 the form of the summer emergence, whilst others remain in the 

 pupa state all through the winter, and appeal- the next spring with 

 the characteristics of those of the spring emergence. Other species 

 of the genus Ennomas are equally marked in their Horoomorphism. 

 This is perhaps the most interesting of all the forms of variation 

 to which I have adverted. It is known to occur in several 

 European butterflies. Araschnia prorsa has its Horeomorphic form 

 hvana, and its intermediate form porima, In America it occurs 

 in a true papilio. Mr. Edwards, in his North American butterflies. 



