154 Of the Animalcules 
\'Tadpoles , they have frequently been called by 
that Name ; though the Tails of them, in 
Proportion to their Bodies, are much longer 
than the Tails of tadpoles are : and it is ob- 
fervable, that the Animalcules in the Semen 
of Filhes have Tails much longer and den- 
derer than the Tails of thofe in other Ani¬ 
mals, infomuch that the Extremity of them 
is not to be difcerned without the bed Glaffes 
and the utmod Attention: their Bodies are 
alfo much fmaller. 
The general Appearance of them, as above 
.defcribed, is fhewn Plate XII. Fig. I. 
In the Spring-Seafon, at the Time that 
Frogs engender, upon opening the Teflicles 
of a Male, and applying fome of th tfefitiml 
Matter before the Microfcope, Multitudes 
of Animalcules appeared therein, about * * one 
thoufandth Part of the Thicknefs of the Hair 
of a Man’s Head, as nearly as could be com¬ 
puted : whence it follows, that a thoufand 
Millions of them would be but equal to a 
Globe whofe Diameter is the Thicknefs of 
the Hair of a Man’s Head. And there feem- 
ed to be ten thoufand of them at lead for 
> each one of the female Ova . 
The Shape of them is given in the fame 
Plate, Fig. II. 
* Leeuwin. Arcan . Nat. Tom. I. Parti, p. 5 1. 
• Upon 
/ 
