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XIII. Note on the Generation q/" Aphides. By George Newport, Esq., F.R.S., 

 Fellow of the Royal College of Surgeons, Sgc. S^c. Communicated by the 

 Secretary. 



Read April 7th, 1846. 



IhE history of the Plant-louse, as ascertained by Leeuwenhoek, Bonnet, 

 Reaumur, and others, is so generally known to naturalists, that it is almost 

 an act of supererogation for any one merely to repeat the observations of 

 those authorities; and we cannot expect to add much to the very ample 

 details they have given. Yet the facts they have recorded respecting the 

 generation of Aphides are in themselves so exceedingly curious, and at the 

 same time are so unexplained by any hitherto received theory of generation 

 deduced from observations on vertebrated animals, that I have been desirous 

 of verifying these facts by direct experiment, preparatory to attempting here- 

 after to show their accordance with some universal law of reproduction. I 

 trust therefore that I may now be permitted in this short note to bear testi- 

 mony to the correctness of the observations of Leeuwenhoek, Bonnet, and 

 Reaumur, on the mode of generation in the Aphides, although at present I 

 can add but little to what has already been observed by those naturalists. 

 The facts I have more particularly endeavoured to investigate, are : first, 

 whether the Aphis is in reality viviparous at one season, and oviparous at 

 another ? and next, whether the supposed ova are deposited as true eggs ; or 

 whether, as imagined by some observers, they are only capsules designed to 

 protect the already formed embryos during the winter season ? 



With these objects in view, I selected the Aphis of the Rose, as best fitted 

 for the inquiry. In the beginning of November 1842, the young shoots of a 

 rose-tree, that had remained in the open air during the whole of the preceding 

 summer, were thickly covered with Aphides, amongst which I had not yet 

 seen any winged specimens ; neither had any of the females yet deposited ova. 

 The rose-tree was placed in the window of an apartment in which there was 



