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XVII. 
And it further appears, by microfcopical Obferva- 
tions, that thefe capillary Canals run parallel to, and 
by the Sides of, the mufcular Fibres in general, or 
to Fibres of whatfoever Nature, where theTe capil- 
lary Canals exitf, This feems a very wife Contri- 
vance in every Degree ; for if their longitudinal 
Direction was crofs the other Fibres, the Circulation 
could not be fo fmoothly nor fecurcly carried on ; 
and therefore would be liable to great Impediments, 
from a tranfverfe PreiTure of the mufcular Fibres up- 
on them; whereas, in this parallel Direction, they 
are fecured from any Impediment, but what pro- 
ceeds from the PreiTure of the Sides of the mufcu- 
lar Cells upon their Sides, in the Performance of 
mufcular Motion : We are here to take notice, that 
the mufcular Fibres receive Twigs from the Arteries 
to nourifh them, and from the Veins to carry back 
the Refiduum into the parallel Canals, as we have 
hinted before. 
XVIII. 
Hence we mud conclude, that no Veffel , of any 
kind whatfoever, opens into the Cavities of the Ceils 
of the mufcular Fibres, but Nerves. 
XIX. 
Of the <^y. Equilibration and Motion of Muffles, 
From what we have premifed, let us endeavour 
to fhew how mufcular Motion is performed, and 
how 
