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living organic particles, or, according to Mr. Need- 
ham, a vegetating force in every microfcopical point, 
capable of forming fecondary combinations, micro- 
fcopical plants, zoophytes or animalcules, according 
to the greater or lefs degree of exaltation, which the 
feveral fubflances have attained. Or whether they 
proceed from ova formerly exifling in the fubflances, 
and capable of enduring a great degree of heat, with- 
out being deftroyed, the germs of which are fooner 
or later developed according to the fitnefs of the ni- 
dus, as is the opinion of the learned and ingenious 
Dr. Parfons, in his treatife of the analogy between 
the propagation of animals and that of vegetables. 
As by entering into a difcuflion of thefe different 
fentiments, one might write a large volume with- 
out perhaps going to the bottom of the matter, I 
fhall here only obferve, that whichfoever of thefe opi- 
nions we embrace, thus far feems to be certain, that 
the earlier or later appearance of microfcopical ani- 
malcules is always in proportion to the degree of ten- 
dency to putrefaction in fuch fubflances as afford 
them. This is the cafe not only with them, but like- 
wife with maggots in meat, which all the world 
knows to be produced from the eggs of flies. 
The two fubflances millepedes and cantharides, 
upon which the above obfervations were made, are 
remarkably putrefcent, and the inflations of them 
flunk abominably in a very fhort time. 
Caflor, though an animal fubftance, and feem- 
ingly very much exalted, treated in the fame man- 
ner as the above-mentioned fubftances, viewed by 
the microfcope every day, and kept for feveral 
months, afforded no animalcules, nor feemed to have 
under- 
