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f When this Blood at every Protrufion came from tlic 
Heart inco the aforefaid Pear-like Veffel, the faid VefTcl 
was very much extended in roundnefs; and then imme- 
diately the extended Parts were again contfaded, or 
drew themfeK^es in, to the end that they migiit in this 
manner regularly, and without intermiffion, protrude 
the piood into the Artery : for if this fort of Velfd were 
not united to the Heart, the Blood couM not be con- 
veniently carry’d into theArteries, becaufe the Arteries 
cou’d not fo largely extend themfelves; and then,' in my 
Opinion, at every Protrufion of the Blood from the 
Hearty there wou’d be a Itop put to its flowincr into 
the Ai teries for a fmall inlfant ot time: whereas in tliis 
cafe the Blood is almoft always running with an eafy 
and conftant Courfe; tho’ at every Protrufion it muft 
be in fonie manner quickned, yet that is fo infenfibly, in 
my Opinion, that no Body can obferve or feel it. 
Now according to this conhant Protrufion of the 
Blood into theArteries of Fifhes^ without the leafl: inter- 
miflion, I am of Opinion, that the fame thing happens- 
as regularly, and after the fame manner, in the Protru- 
fion of Blood out of the Heart into the Arteries of Beads- 
and the rather becaufe we always find, that the Great 
Creator of all things does bring about his Operations in 
the bigger Creatures, after qnc and the fame manner 
tho’ their Hearts are of a different Figure from thofe of 
^ I have formerly communicated to the Honourable So- 
ciety fome Difcoveries of mine, relating to the Circula- 
tion of the Blood in Eels, confiding in this to wit, that 
the Blood coming out of a great many fmall Vcifels in 
the Tail of an Eel, falls in, and is united in one greater 
Blood- Velfel, where is the fird beginning of the Fid?- 
Bones, and where the Blood runs thro* a Valve whidi J 
have not only obferved my felf, but ha ve Jikewife fliewn 
to feveral Curious Gentlemen, who view’d it with a- 
bundance 
