Royal Society. 465 
of the larger particles, with its inclofed particles, (that were 
increafed lo much in bignels, that they were ready to be emitted) 
which lay more regularly here, than in any of the reft, where 
there was not the ordinary motion, which made M. Leeivehhoek 
believe that this was occafioned by the inclofed particles not lying 
all equally diftant from their center, and that thofe that lay far- 
theft from the center made one fide of the incloiing round par- 
ticle heavier, which hindered the motion. 
When M. LeeiJOenboek perceived that the great number of 
round particles in the great glafs mixed with a great number of 
Animalcules, were gone in three days time, he considered whe- 
ther thefe particles were not created as food for the Animalcules z. 
Now when we lee, that the abovementioned globules did not pro- 
ceed from themfelves, but by procreation, as we know that all 
plants and feeds are procreated," each feed, tho' ne^-er lb fmall, 
having its plant inclofed within it; we are now more than ever 
afTuredof the procreation of all things; M. Lee^ivenhcek lays it 
down as a certain truth, that the fmall round particles found in 
the great ones are leeds, and that without them the round parti- 
cles could not be produced. 
M. Lee'^enhoek caught a little frog, which he judged had 
been an egg the preceeding fpring, and putting it into a glals- 
tube an inch wide and ten inches long, he flopped both the ends 
up with cork, yet after fuch a manner, as that the air had free 
admifTion at one end; he viewed the toes of the fore-legs with a 
magnifying- glafs to obferve the circulation of the blood, which 
he could difcern with great difficulty 3 but when he came to 
look upon the hindmoft legs, he fl\w feveral days fucceffively 
iipon the Ikins between the toes, made on purpofe to Iwim 
withal, as in all water-fowls, the blood circulate in leveral 
very fmall veffels ; he alio obferved, that when the frog ftretched 
out its leg, the circulation was thereby ftopt for a little time, but 
when it had ftood ftill, the blood began to circulate agam; the 
reafon of which he imagined was, that when the animal thruft 
its legs againft the glafs to climb up, that then the blood-veffels 
were thereby compreffed, and the circulation hindered; after the 
frog had been 24 hours in this tube, M. Lee-wenboek oblerved its 
excrements as it were in a heap ; after it had been 48 hours there, 
it fouled again, and looking thro' a magnifying-glals he oblerved 
in the firii excrement, that it had fed upon an animal, whole 
body was befet with hairs of various thickneis, very /harp 
pointed, which he judged to be Ibme flying infcfl; when he 
viewed the fecond exciement, he oblerved no hairs at firft; but 
Vol. III. N n n upo« 
