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leallas far as I know) that their eggs are formed in their bodies be- 

 fore they come out of their aureha thite ; it will follow, that Fleas 

 immediately upon their coming forth into life out of their webs, 

 can copulate, and in three or four days time lay eggs, fo that in 

 the fpacc of twenty-eight days, from a newly laid egg, a Flea may 

 be produced. This being the cafe, it is no wonder that in the 

 fummer we at fomc times perceive no Fleas in our houfes, and at 

 other times they appear in great numbers without being brought from 

 elfewhere ; and if we alfo fuppofe, as I am "VN'ell allured is the cafe, 

 that Fleas, after they have copulated and laid the eggs which they 

 had within them, do then die, we may conclude that we are not 

 tormented for a long time by one and the fame Flea. 



But whereas many flying infects do, within a few fucceffive 

 days, lay all their eggs, <his is not the cafe with Fleas ; for a Flea, 

 which in one day or night laid 4, 5, 6, 7, 8, and even 12 eggs, 

 being afterwards fhut up in a glafs laid no more, though upon 

 opening it, I found in its body many eggs remaining, fome of 

 which were exceedingly fmall, whence I concluded that a Flea 

 being fo fhut up, its laying no more eggs was occafioned only by 

 want of food. To fatisfy myfelf in this respect, I took feveral 

 female Fleas, after they had laid their firft parcel of eggs, and 

 contrived to confine them on my hand, In order that they might 

 thence get a fupply of nourifliment : one of thefe fucked the blood 

 with great avidity, standing as it were \ipon its head, and lifting 

 up its hintler and middle feet with a quivering motion in them, 

 this Flea the following day laid two or three eggs, and two or three 

 days fucceirively afterwards, I placed it again on my hand, that it 

 might get a further fupply of food, but in vain, for it did nothing 

 but leap about and endeavour to efcape. The like happened to me 

 in feveral other trials I made, but if the Fleas would have con- 

 tinually fed on my arm or hand, I would have done my befl to 

 ascertain what is the natural term of this creature's hie. 



On this occafion I cannot but obfervc that we meet with many 



