on Mufcular Motion. 29 
experiment made on the iubjeCl, that all motion arifes from 
particles coming near one another in fome direction. It would 
be fuperfluous for me to point out thefe experiments ; I fhall 
mention one only, and an obvious one. Lay bare a mul'cle, 
and prick any of its fibres, it immediately becomes fhortcr. 
The original power of coming nearer to one another of two 
or more particles of matter, has been called attraction. There 
have been feveral original powers of coming nearer one ano- 
ther of particles of matter, which have been conlidered as dif- 
ferent attractions, fuch as the attraction of gravitation, of 
magnetifm, of eleCtricity, &c. ; all of which this Society are 
too much matters off, for me to enter into any difquifition 
with regard to them. 
The attraction which is my prefent objeCt, I call the attrac- 
tion of life. This attraction is either of two fpecies, or is 
exerted varioufly ; for all the moving parts have their particles 
nearer one another in the living than in the dead body. The 
proof of this is as neceffary as it is obvious. I muft, there- 
fore, take up a fmall portion of your time in pointing it out. 
Take the body of any animal, when the life is entirely gone 
from it, and the effeCts of it are entirely loft, but before any 
putrefadion, or any change in its chemical qualities, has taken 
place ; and lay bare, and difteCt out, any mul'cle, efpecially one 
which has long fibres, and no middle tendon, fuch as the fario- 
rlus, for example, and afterwards lay it in its place, leaving it of 
the length it naturally takes ; it will reach farther than from 
its origin to its infection ; but lay bare, and diffeCt out, the 
fame mul'cle in the living body, and it will always be fhorterr 
than from its origin to its infertion If it fhould be faid, that the 
difleCtion ftimulated the mul'cle, and brought it into ad ion, 
let it not be difleCted out, but its -tendon cut through, as the 
Tendo . 
