C 3°7 3 
I fpread it thin on a glafs, or a piece of talk. It 
then occurred to me to dilute it, but not with 
water, for this I knew difiolved the particles; but 
with ferum, in which they remain undiffolved. By 
the ferum 1 could dilute it to any degree, and there- 
fore could view the particles diftindt from each 
other ; and in thefe experiments I found that thefe 
particles of the blood were as flat as a guinea. I 
likewife obferved that they had a dark fpot in the 
middle, which Father de la Torre took for a hole; 
but, upon a careful examination, I found it was not a 
perforation, and therefore that they were not annu- 
lar. I next made experiments by mixing theie 
particles with a variety of other fluids, and examin- 
ed them in many different animals.; and the rJult 
of thefe experiments was, that their fize is differ- 
ent in different animals, as is feen in plate XII, 
where they are reprefented of the fize they appeared 
to my eye, when viewed through a lens of Tr 
an inch focus, which, allowing eight inches to be 
the focal diftance of the naked eye, magnifies the 
diameter 184 times. 
It may not be improper to obferve here, that the 
accurate Leeuwenhoeck not having diluted the hu- 
man blood, or that of quadrupeds, fo as to fee 
thefe particles feparate from each other, was thence 
not qualified to deferibe them from his own ohfer- 
vation, as he has done thofe of fifli and of frogs ; 
and, fufpedting a round figure was more fit for 
circulating in our veffels, was thence led to fup- 
pofe thefe particles fplierical in the human fubjedfi. 
But I fhall hereafter be able to fhew from his 
own words, that it is not his ohfervations, but 
Vol. LX h i. S f his 
