220 
Of the common Fly. 
difHn&dy, working from the Stomach to¬ 
wards the Anus j and alfo the Motion of 
the Lungs, contracting and dilating them- 
felves alternately. Upon opening a FJy, num- 
berlefs Veins may likewi-fe be difcovered, 
difperfed over the Surface of its Inteftines: 
for the Veins being biackifh, and the Intef- 
tines white, they are plainly vifible by the 
Microfcope } though two hundred tboufand 
Times flenderer than the Hair of a Man’s 
Beard. According to * Mr. Leeuwenhoek, 
the Diameter of four hundred and fifty fuch 
minute Veins were about equal to the Dia¬ 
meter of a fingle Hair of his Beard ; and 
confequently two hundred thoufand of them 
put together would be about the Bignefs of 
fuch an Hair. 
In mod; Kind of Flies the Female is 
furnifhed with a moveable Tube at the End 
of her Tail, by extending of which fhe 
can convey her Eggs into convenient Lloies 
and Receptacles, either in Flefh or fuch 
other Matters as may afford the young-on.es 
proper Nourishment. From the Eggs come 
forth minute Worms or Maggots, which 
after feeding for a while in a voracious Man¬ 
ner, arriving at their full Growth, become 
transformed into little brown Aurelias; 
* Arc tit at. Tom, II. p. 77. 
whence, 
