312 PHYSIOLOGY. 



as well as in all the other genera of Lepidoptera, the copulation of 

 the sexes and the impregnation of the female is regularly requisite to 

 the development of the eggs, but that it probably takes place whilst 

 the fully developed female still remains in the case spun for her pupa ; 

 at least he detected the escaped females in this situation, and saw them 

 placing their heads and sometimes their anus at the aperture of the 

 case. 



But the other cases here and there observed as sporadical, and which 

 consequently belong to the second group, are not thereby contradicted. 

 That unimpregnated individuals lay eggs may be observed in the females 

 of all the Bombycida, if, some days after their escape from the pupa case, 

 they be impaled and allowed to die slowly. The females of the Sphinges 

 do the same, but never the butterflies, according to Roesel's observa- 

 tions, nor likewise the unimpregnated females of the Coleoptera, as 

 Suckow remarks *. Among the other orders I remember to have 

 observed only some Diptera, particularly the Tipulce, to lay eggs in 

 the convulsion of death ; for example, species of the genera RhypJms, 

 Mycetophila, and Tachydromia. But from these eggs it is but rarely 

 that young are disclosed, and indeed only from some, and not from all 

 that are laid. The earliest instance on record is probably that related 

 by Albrecht f, next to which is that related by Pallas, and observed 

 by him in Euprepia casta, O. (Bomlyx casta, Fab.). An instance is 

 known of it in Gastrophaga potatoria, O. Bernoulli relates several 

 instances, one in Gastrophaga quercifolia, O. (papillon paquet de 

 feuilles seclies), which his friend, Professor Easier, had seen. He 

 reared the caterpillar, it changed into a pupa, the imago came forth, 

 Avhich after a short time laid eggs, from which young caterpillars came. 

 A second case Bernoulli himself observed in Episema cceruleocephala, 

 Tr. Lastly, L. C. Treviranus | has observed the same spontaneous 

 development in Sphinx Ligustri, Suckow , in Gastrophaga Pint, O., 

 and my friend, Dr. Al. V. Nordmann, recently in Smcrinthus Populi. 

 According to Lange || and Schirach ^[, the queen bee will sometimes lay 

 unfruitful eggs without copulation with the drone, and indeed the females 

 produced by such eggs will again lay productive eggs without having 



" In Heusiuger's Zeitschr., f. d. Org. Phys. vol. ii. p. 264. 



t Miscell. Acad. Nat, Cur. an. 9 et 10. D. 3. obs. 11. p. 2U. 



Venn. Scbiift, vol. iv. p. 106. In Heusinger, 263. 



II d'eineinnutzigc Arbeiten tier Sa'chsis, Biencngesellscb, vol. i. part i. p. 39. 



f Ib. p. 155. 



