2Bo Of the Wheel Animal, 
much the fame Time as the Pulfations in 
the Arteries of a Man in Health j as I have 
often proved by feeling my own Pulfe whilft 
I have been .viewing them. In each of the 
femi-lunar Parts there appears a Cavity, 
which Teems to clofe when thofe Parts come 
together, and to open itfelf again when they 
feparate. . 
The Motions of the Heart are communi¬ 
cated to all the other internal Parts of the 
"Thorax ; and indeed feem to extend a great 
Deal farther; for a flriCt Examination dif- 
covers, at the fame Time, throughout the 
whole Animal, Contractions and Dilatations 
going on that are apparently correfpondent 
thereto. 
It is however neceffary to remark, that 
thefe Motions of the Heart are, fometimes, 
as it were fufpended, or unperceivable for 
two or three Minutes, after which they be¬ 
come renewed, and go on again with the 
fame Vigour and Regularity as before. And 
this Sufpenfion of the Syfble and Diaflole, 
has made fome Gentlemen, to whom I have 
fhewn it, doubtful, whether the Part we 
have been defcribing can therefore be the 
Heart. But their Doubt arifes wholly from 
a Suppofition that the Hearts of minute In- 
feds muft continue beating with the fame 
Conftancy, and be fubjed to the fame Laws, 
as the Hearts of the larger Kinds of Animals, 
which probably is not the Cafe. 
/ _ 
The 
