166 INTERNAL ANATOMY OF INSECTS. 



stances she never attempts to leave the pupa-case in 

 which she has been disclosed, but that being there im- 

 pregnated by the male, she there also, apparently after 

 the manner of the female Cocci, deposits her eggs, which 

 hatching produce young larvae that make their way out 

 of the case, and thus seem to originate without maternal 

 interference a . 



But the most remarkable fact bearing upon this head, 

 though as relating to a viviparous insect it does not 

 strictly belong to it, is the impregnation of the female 

 Aphides, or plant-lice, before alluded to b . If you take a 

 young female Aphis at the moment of its birth, and ri- 

 gorously seclude it from all intercourse with its kind, 

 only providing it with proper food, it will produce a 

 brood of young ones : and not only this ; but if one of 

 these be treated in the same way, a similar result will 

 ensue, and so on, at least to thejifth generation ! ! to 

 which period Bonnet, who first made an accurate series 

 of observations on this almost miraculous fact, success- 

 fully carried his experiments, till the approach of winter 

 and the want of proper food forced him to desist c ; and 

 Lyonet extended it still further d . It is now generally 

 admitted as an incontestible fact, that female Aphides 



a It does not appear to be clearly decided whether the eggs are ex- 

 truded from the female, or whether dying immediately after fecunda- 

 tion they are hatched within her body. As the young Iarva3 cer- 

 tainly are hatched in the pupa (not merely within the exterior case 

 of bits of grass, &c., which includes it) which the body of the insect 

 must fill, it does not seem easy to conceive how she can find room 

 for oviposition ; and yet Von Scheven expressly says that one female 

 of Ps. vestita which being kept from all access to the male actually 

 left the pupa-case and wandered about the glass which contained 

 themlaid unfruitful eggs. b VOL. I. p. 32, 175. 



c Bonnet i. 19. (l Reaum. vi. 551. 



