I 
in Semine Mafculino. 165 
As the Animalcules in the Semen Mafculi - 
nnm of different Creatures are not much un¬ 
like in Shape, it is alfo obfervable, that they 
do not differ in * Bignefs according to the 
Sizes of the Creatures they are taken from ; 
but feem, in this refpedt, analogous to-the 
Seeds of Trees and Plants, whofe Size bears 
very little Proportion to the Bignefs of the 
Trees and Plants producing them. The 
Seed of an Apple, for Inftance, is fome 
thoufands of Times fmaller than a Cocoa- 
Nut, tho* the Trees they grow on have not 
that Difproportion : and the Seeds of To¬ 
bacco (whereof a thoufand weigh not 
above a fingle Grain) are lefs beyond Corn- 
par i foil than many Kinds of other Seeds whofe 
Plants are not near fo large as Tobacco is„ 
Hence it comes to pafs, that Animalcules 
maybe difcovered in th Semen of the fmalleft 
Birds,Quadrupeds, and Fifhes, nay, and even 
in Infedts too. For Mr. Leeuwenhoek 
affures us, he found a white Matter he had 
fometimes fqueezed from the hinder Parts of 
male J Spiders, about the Bignefs of a Graiti 
of Sand, to be indeed their Semen , by difco- 
vering therein prodigious Multitudes otAni” 
malcules , which continued living above five 
Hours, but were fo extremely minute that 
he fuppofes a thoufand Millions of them 
?- —.— 1 --- - — - 
* Arc. Nat. Torn. IV. pag. 30. + Dr. Power’s Ex- 
periip. pag. 30. J Pbilojopk* Tranfafi. Numb. 279. 
would 
* / 
