250 Dr. Wells’s Observations on an Influence 
in this way sufficiently often to place the fact beyond doubt, 
I next began to consider its relations to other facts formerly 
known. I very soon perceived, that the immediate exciting 
cause of these motions could not be derived from the action 
of the metals upon the muscle and nerve, to which they 
were applied ; otherwise it must have been admitted, that 
my body and a metal formed together a better conductor 
of the exciting influence than a metal alone, the contrary of 
which I had known, from many experiments, to be the case. 
The only source, therefore, to which it could possibly be re- 
ferred, was the action of the metals upon my own body. It 
then occurred to me, that a proper opportunity now offered 
itself of determining, whether animals contribute to the pro- 
duction of this influence by means of any other property than 
their moisture. With this view, I employed various moist 
substances, in which there could be no suspicion of life, to con- 
stitute, with one or more metals, different from that of the 
coatings of the muscle and nerve, a connecting medium be- 
tween those coatings, and found that they produced the same 
effect as my body. A single drop of water was even sufficient 
for this purpose ; though, in general, the greater the quantity of 
the moisture which was used, the more readily and powerfully 
were contractions of the muscle excited. But, if the mutual 
operation of metals and moisture be fully adequate to the ex- 
citement of an influence capable of occasioning muscles to 
contract, it follows, as an immediate consequence, that ani- 
mals act by their moisture alone in giving origin to the same 
influence in Mr. Galvani’s experiments, unless we are to ad- 
mit more causes of an effect than what are sufficient for its 
production. 
