in Semine Mafculino. 155 
Upon viewing the Milt or Semen Mafcu\ 
Unum of a living Cod-fifh with a Microjcope , 
fuch Numbers of Animalcules with long 
Tails were found therein, that at leaf! ten 
thoufand of them were fuppofed to exift in 
the Quantity of a Grain of Sand. Whence 
Mr. Leeuwenhoek argues, that the Milt 
of that fingle Cod-fifh contained more living 
Anhnalcules than there are People alive upon 
the Face of the whole Earth at one and the 
fame Time : for he computes *, that one 
hundred Grains of Sand make the Diameter 
of an Inch ; wherefore in a cubic Inch there 
will be a million of fuch Sands. And as he 
found the Milt of the Cod-fifh to be about 
fifteen cubic Inches, it muft contain fifteen 
millions of Quantities as big as a Grain of 
Sand. Now if each of thefe Quantities con¬ 
tain ten thoufand Animalcules , there muff 
be in theWhole one hundred and fifty thou¬ 
fand millions. 
Then, to find out, in a probable Manner, 
the Number of People living upon the whole 
Earth at one Time; he reckons, that in a 
great Circle there are five thoufand four hun¬ 
dred Dutch fquare Miles 5 whence he cal¬ 
culates the Surface of the Earth to contain 
nine millions two hundred feventy-fix thou- 
* Arc. Nat. Tom. I. Par. II. p, 9, 
Voe. I» M fand 
