which incites the Muscles of Animals to contract. 253 
of the moisture of the animal ? Further, a consequence of this 
opinion, is, that, if the under surfaces of two different metals 
be placed in moisture, and their upper surfaces be afterwards 
connected by means of a nerve, still attached to its muscle, 
contractions ought then to be produced ; since the whole quan- 
tity of the electric fluid necessary to restore the equilibrium, 
which has been disturbed by the action of the metals, must 
pass through the nerve. This experiment I have made, and as 
I did not find the muscle to contract, I must hold Mr. Volta's 
opinion on this point to be likewise ill founded. The fact is, 
that as far as the contraction of muscles is a test, whether the 
influence exists or not, and we have no other, it is never ex- 
cited, when two metals, or one metal and charcoal are neces- 
sary for this purpose, unless these substances touch each other, 
and are also in contact with some of the fluids formerly men- 
tioned. 
But there is still another requisite for the excitement of the 
influence, which is a communication, by means of some good 
conductor of electricity, between the two quantities of fluid, 
to which the dry exciters are applied, beside that which takes 
place between the same quantities of fluid, when the dry ex- 
citers are brought into contact with each other. As from this 
last circumstance, a complete circle of connection is formed 
among the different substances employed, it has been imagined 
by many, that the individual quantity of the influence excited 
goes the whole round, each time contraction is produced. 
There is an experiment however, first, I believe, made by Dr. 
F owler, which appears to contradict this opinion. He brought 
two different metals into contact with each other in water, at 
the distance of about an inch from the divided end of a nerve, 
MDCCXCV. LI 
