C 309 ] 
Lemma II. 
A mufcle of voluntary motion, in its natural ffate, in 
a living animal body, being given, it will contract 
by the introduction of a warm mild fluid, into its 
flefhy fubftance in every part. 
If this be denied, let the body of an animal be 
taken quickly after death, and the crural artery be 
pierced, and a warm mild fluid be injeCted into it : 
we fhall then fee the mufcles, to which the artery 
belongs, quicken and contract, as if the living ani- 
mal moved them. This experiment was known to 
Mr. Cowper, and is confirmed by Albinus (fee Hiji. 
Mu fc. p. 21.) 
But if this effedt is conffantly produced foon after 
death, how much more when the animal is alive ? 
Therefore a mufcle of voluntary motion, in its na- 
tural Bate, in a living animal body, will contraCt, 
by the introduction of a warm mild fluid, into its 
flefhy fubftance, in every part : Which was to be 
proved. 
But here it may be objected, with fome appear- 
ance of reafon, that there is a warm fluid, the liv- 
ing blood, in every part of the flefhy fubftance of 
all the mufcles, during the life of the animals; 
and yet it is a faCt, that no mufcle of voluntary 
motion contracts, but at the command of the will, 
morbid cafes excepted. This objection comes dole 
to the original queftion, and however reafonable 
it may feem, will quickly vanilh before fome com- 
mon obfervations concerning the objeCts of fenfe in 
general, and their manner of operating upon the 
different organs, fo far as it univerfally agrees. 
We 
