[ 22 ] 
On touching the uncut nerve with a 
conductor at the point where it was coated, 
and at the fame time the naked part of it, 
or the mufcjes of the correfponding leg, 
the fmallefl fliock has not taken place, yet 
the animal from time to time moved this 
leg, although it would not obey the force 
I exercifed upon it; at other times, the 
frog did not fhew any fpontaneous move¬ 
ment, whilft I could excite violent ones in 
it. Thefe accidents are not common. 
It fometimes, though rarely happens, that 
on approaching the exciter to the coating 
and the leg at the fame time, the limb 
remains motionlefs, and the animal by its 
difficult refpiration and a plaintive cry, 
plainly Ihews that he experiences pain. 
Of all the animals upon which I have 
jmade experiments, frogs preferve their 
vitality the longeft. Formerly I attempted 
to eftabliffi a meafure for this principle, 
but my calculations were imperfedt, for 
the reafon I am about to adduce. 
I was 
