th SEMINAL VERMICULI. 2y 
air. The tubes’ were fo drawn out, that the thin- 
nefs of the glafs permitted me to fee the vermi- 
culi within. The peculiarities they prefented 
were very different from thofe of the reft. All, 
or at leaft moft of them, had a fingular mode of 
moving ; fome had that kind of motion obferved 
in thofe expofed to-the open air; others had a 
continual irregular motion, changing from: ve- 
locity to inaCtion and reciprocally ; others ftop- 
ped entirely, and, after refting feveral minutes, . 
refumed their former rapidity: we did not fee 
them inconfiderately ftrike. againft the folid por- ' 
tions of the femen,o.as was xemarked in the: 
firft chapter, but always avoiding them and 
turning afide or retreating. Thefe’ peculiari- 
ties indeed fucceeded better, and :with more. 
uniformity, when the tubes were kept warm. I 
have before faid, the longeft period of life:of the: 
human vermiculi is feven er eight hours. whem 
expofed to the open air; but how much.jisi 
it prolonged when they are included in tubes ? 
In fummer I have fucceeded in preferving them. 
two days or more, and in fpring and autumn al 
moft three (1). 
It 
(1) Authors difpute very much concerning the duration 
of the life of thefe animals. Some have fuppofed they live 
only a few hours, and others, feveral days. Leeuwen- 
hoeck is a moft exact obferver; he fays, he put the fe- 
men 
