[ * ] 
plication of which fcems to be the chief Defign of 
the Learned Founder of thefe Lectures) I fhall wave 
all fuch Enquiries, and proceed diredly to inveftL 
gate by what Means a Mufcle fo inftantly and forci- 
bly contracts itfelf, or ffiortens its Length, at the 
Command of the Will? and this I fhall endeavour 
to do by fuch Rules and Laws as are fimple, uni- 
form, and intirely agreeable to the known Syftem 
of the Univerfe. 
III. 
t ; I ’ ■) v' ' V I t I ' V i | I 
In order to the eafier Illuftration of this wonder- 
ful and important Property in the Fibres, I fhall give 
you, i Jl, An analytical View of the component 
Parts of a Mufcle. idly, I fhall fhew the true Caufe 
of Cohelion, Tenfion, and Elafticity in the animal 
Fibres, idly, I fhall make it appear, that every Fi- 
bre conftituting a Mufcle, is, in its ultimate Divifion, 
tubular, and not a Chain of Veficles or Bladders. 
And, laftly, I fhall prove it to be more than pro- 
bable, that Mufcular Motion proceeds from the at- 
tractive Quality of the conftituent Particles of every 
Fibre being increafed and ftrengthencd by the Addi- 
tion of fome athereal Matter flying out from the 
Extremities of the Nerves; and that this is inftantly 
occalion’d by the Will, and ceafes again as foon. 
IV. 
By a chemical Analyfts of a Mufcle difle&ed from 
the Buttock of a lean Ox, which weigh'd exactly 
two Pounds Averdupois , I procured, 
i* 
