112 INSECT TRANSFORMATIONS. 



not ascertained) was discovered by R'aumur to be ovo- 

 viviparoiis; but the embryo flics were not arranged in 

 the pouch in the same spiral form as the preceding, but 

 longitudinally. These did not appear to be quite so 

 numerous; and they had a peculiar breathing appara- 

 tus, which, when shut, as it could be at pleasure, ap- 

 peared in the form of a crown. 



Amongst several other ovo-viviparous flies discovered 

 by R aumur, there was a very minute tipulidan gnat 

 (species not ascertained) with a jet-black body, white 

 wings, and beaded antennse, not larger than the head 

 of an ordinary pin, which was bred in great numbers 

 from some cows' dung put into one of his nurse-boxes 

 for another purpose. He justly remarks upon this cir- 

 cumstance, that 'the minute and the grand are nothing, 

 or rather are the same, to the Author of nature.' 



The numerous genus Aphis presents the singular 

 anomaly of producing eggs in the autumn and living 

 young during summer, and, as Curtis tells us, even 

 during winter in green-houses. De Geer, however, 

 ascertained that it was not the same individual aphides 

 which at one season produced young and at another 

 eggs, but different generations * By a series of very 

 careful and troublesome experiments Bonnet also ascer- 

 tained the curious fact, that in three months nine gene- 

 rations of these insects may be produced in succes- 

 sion, though the males be rigorously excluded from the 

 nurse-boxes where the females are isolated. In fact 

 all the aphides produced in spring from the eggs laid 

 in autumn appear to be females; and no males are pro- 

 duced till the end of summer, a short time before the 

 eggs are deposited for winter. Among both males and 

 females are some with and some without wings, — the 

 nature of which distinction does not appear to be yet 

 ascertained. 



* De Geer, Mem. des Insectes, ill, 70. 



