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CXXIX. 
Let us now return to our fecond Query, and exa- 
mine whether the nervous <iyEther is tranfmitted 
from the Brain to the Heart, in a pulfatory Man- 
ner, at equal Diftances of Time.; or whether fome 
Interruption is only given to its Influx into the 
mufcular Fibres, when the Heart is in its Syftole . 
CXXX. 
In order to underdand this, we mud look back 
and conftder, that, according to our Theory, if the 
ethereal Medium in the Nerves was perpetually 
flying into the mufcular Fibres of the Heart, it would 
be conftantly contracted, notwithftanding the Mo- 
mentum' the Blood, the Contraction of the Auri- 
cles, or the Vis Rejiitutionis in the ftretched-out 
Fibres. Hence then it is evident, that the alternate 
Contractions and Dilatations of the Heart pro- 
ceed from an alternate Influence of the nervous 
<^yEther> but how this Alternation happens, when 
the Nerves which fupply the Heart are not, in the 
lead, under the Direction of the Will, is the Diffi- 
culty we labour under. 
CXXXI. 
In all the Nerves which fupply the voluntary 
Mufdes, it is certain there are Redridions in fonle 
Parts of them which the ethereal Matter is not able, 
to dilate without an additional Impulfe from the 
Will i 
