£ 97 1 
feen many frogs of the fame colour the 
inflant they have been killed. 
In thefe . cafes, the irritability of the 
mufcular fibre, and the vital principle 
appeared to be retained ; but I cannot 
however omit obferving, that the move¬ 
ments were fometimes very feeble, al¬ 
though the animal fubmitted to the expe¬ 
riment, was before well furnifhed with 
vitality. This fa& fliews, that in a flate 
of pain, the nerves fuffer under certain 
circumftances very eflential changes. 
Experiment XCVI. 
Inflammable air, or hydrogena gaz, did 
not a£t with increafed power, or rapidity 
upon frogs, in which the heart and brain 
were expofed. 
Experiment XCVII. 
The heart when removed from the body 
and placed in inflammable air, palpitated 
with the fame fwiftnefs and force. 
H Expert- 
