4494 Insects. 



conclusion to which we have just arrived, it may be well to refer to 

 the views of others upon the exact signification of these singular 

 reproductive phenomena. 



Those old entomologists, such as Bonnet, Reaumur, De Geer, &c. 

 who were the first to observe, besides verifying beyond all doubt, 

 these peculiar phenomena, all believe that each brood constitutes 

 a separate generation and that the reproduction takes place by true 

 ova, as in the common generative act of other insects. This wide de- 

 viation from the ordinary course of nature, as it seemed to them, they 

 attempted to explain and reconcile by various theories. Thus 

 Reaumur affirmed that these viviparous individuals were androgy- 

 nous; and, in later times, Leon-Dufour, who knew too well the anato- 

 mical structures of insects to believe with Reaumur that they could 

 be hermaphrodites, referred these phenomena to spontaneous or equi- 

 vocal generation. 



Morrem, who made somewhat extended researches on the anatomy 

 of Aphis Persicae, and especially of its generative organs, advanced the 

 novel theory that these broods were developed in the body of the 

 virgin parent, by a previously organized tissue becoming individualised 

 and assuming an independent life, exactly as he believed to be 

 the case with Entozoa. To each and all of these views it scarcely 

 need be said that they would be wholly inadmissible, according to the 

 present established doctrines of physiological science, even had 

 we no directly controverting observations. 



But there are other explanations or views which deserve more atten- 

 tion. The first of these is that advanced by Kirby and Spence. 

 According to them, " One conjunction of the sexes suffices for the im- 

 pregnation of all the females that in a succession of generations 

 spring from that union." In support of the reasonableness of this 

 hypothesis, they quote several instances which they regard as of 

 analogous character; thus they say, in regard to the hive-bee, that 

 "a single intercourse with the male fertilizes all the eggs that are 

 laid for the space of two years." 



In this connection should be mentioned the similar hypothesis ad- 

 vanced for a like purpose by Jourdan. According to him many 

 Lepidoptera lay fertile eggs when completely isolated from the males ; 

 such are Euprepia casta, Episema caeruleocephala, Gastropacha 

 potatoria, G. Quercifolia and G. Pini, Sphinx Ligustri, Smerinthus 

 Populi, and Bombyx Querci. 



But all these cases have really no strict analogy with that of 

 the Aphides in question ; for there is not, as with these last, a succes- 



