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at pleafure. Late anatomifls have tried it upon lefTer 
veffels, with the fame conftant fuccefs. (Vide Albini 
hijior. mufcul. p. 19.) 
In a living animal, if you tie the nerve, that fup- 
plies a given mufcle, that mufcle is diiabled from 
adting at the command of the will. This experi- 
ment is diftindtly mentioned by Galen in his treatife- 
on the mufcles, and is approved by the trials of later 
anatomifls. [Alb. p. 19.) 
From thefe two experiments it is clear, and gene- 
rally agreed upon, that, in order to the performance 
of voluntary mufcular motion, befides the particular 
ftrudture, there is required an abfolute freedom of 
the blood-veffels, and the nerves. 
Mufcular motion is obferved to be voluntary, and 
involuntary. Of the firfl kind are almoft all the 
mufcles of an animal body ; of the latter, the only 
complete inftance is the heart. The firft feems more 
complex than the latter, fince, befides the motion, 
it implies an additional adt of the will. Effedts, that 
are lefs compounded, ought naturally to precede ef- 
fedts, that are more ; thefe receiving light from the 
former, where both are homogeneous. For this 
reafon, I have placed here two lemma’s relating to 
automatic, or involuntary motion. 
Lemma I. 
The heart, in its natural flate, in a living animal 
body, being given, its contradtion proceeds folely 
from, or is mechanically caufed by, the warm 
blood, flowing into and filling its flefhy fubftance 
in every part. 
