[ 56 ] 
was a want of uniformity in this refpedt. 
On repeating it, I remarked that fome 
frogs continued to move with vivacity, 
that others gave very feeble (hocks, which 
did not laft long, and others again re¬ 
mained altogether motionlefs. 
3 at firft thought this derived from a 
difference in the conftitution of the animals; 
but as one day I obferved, that in the fame 
frog one leg was completely motionlefs, 
whilft the other was agitated by violent 
convulfions, I entirely gave up this opinion. 
Experiment XXIII. 
With a view to di(cover the real caufe 
of this circumftance, I made ligatures at 
different heights in ten frogs; all of them 
moved except two, in which the ligature 
was in contadt with the mufcles. I now 
ftretched the nerve a little, fo that the liga¬ 
ture was at a very fmall diftance from the 
mufcles without touching them. On hav¬ 
ing 
