[ 6o ] 
to involuntary Motion, could not have any Motion 
at all, having no Antagonift. Therefore, in general. 
Motion muft be caried on more limply, and in the 
Manner explain’d above. 
XXVII. 
Yet an ^^Equilibrium between a Mufcle and its 
Antagonift is abfolutely neceflary ; but it is only f<j 
in order to preferve the Equipoize between them, 
•while both are in a State of Reft. Now there are 
two Sorts of c/ Equilibriums proper to Mufcles, the 
one which is peculiar to each Mufcle in itfelf, ex- 
plained before, and the other that which is between 
two Antagonifts. Let us fee how the latter is broke, 
in order to Motion. 
XXVIII. 
We are to confider two Antagonifts exadly equi- 
librated, before any Adion is begun in either. The 
Mind, now refolving to ad with one Mufcle, makes 
an Impulfe upon the Nerve leading to it. The Cells 
in that Mufcle are inftantly inflated beyond their Tone 
of Reft, to the Degree neceflary for the particular 
Adion intended : The Blood is flopp’d, as mentioned 
before, in the little venal parallel Canals ; and the 
Mufcle is contraded beyond its Tone of Reft. And 
at the fame Inftant that the Mind impels the in- 
flating Matter into the Cells of the Mufcle in Mo- 
tion, (he remits to determine any to the Antagonift, 
which caufes a Retraffiion of it into the Nerves: By 
this means] the interftitial Air, in this, exerts its 
eiaftic Force, comprefles the Sides of the Cells* 
whereby 
