a “SEMINAL VERMICULI. r 
outlines fo well defined, as with a perfe& micro- 
feope formed of a fingle lens. This is a fa@ ac- 
knowledged by ail .obfervers, and my own ob-. 
fervations on feminal vermiculi with both micro- 
fcopes confirm it more. Ufing the firft, I faw 
the vermiculi precifely as has been defcribed : 
with the fecond, I had a confufed view of the 
body, and was frequently in doubt whether it 
was round or oval; the outline was always in a 
fort of mift or cloud. The tail, which is infinite- 
ly more delicate, appeared lefs fenfible, and could 
only be diftinguifhed as a very long lender body, 
It is not furprifing, therefore, that M. de Buffon 
calls this part of the vermicule a foreign fub- 
ftance, a kind of long, delicate, fubtile filament, 
fince it truly appeared fuch to him when viewed 
with the compound microfcope. 
It may perhaps be thought that my cenigidand 
microicope was not fo good as M. de Buflon’s ; 
but thofe I ufe are the moft perfe& now made in 
London. I was defirous to view {permatie.ver- 
miculi with the microfcope M. de Buffon’ had 
employed, that is, Cuff’s microfcope, which is 
precifely that of Mr Needham, and which, M. de 
Buffon obferves, he ufed in his examination 
of the feminal fluid. But it fhowed me no- 
thing more; and I may affirm that my obferva, | 
tions and experiments on feminal vermiculi, as 
well as on the animalcula of infufions, and fimi- 
lar 
