248 Dr. Wells's Observations on an Influence 
end to the external surface of the muscle which it entered, 
without ever observing motion to follow. I think, therefore, 
I am entitled to conclude, not only that the theory advanced 
by Mr. Galvani, respecting the cause of the muscular mo- 
tions in his experiments, is erroneous ; but also, that the in- 
fluence, whatever its nature may be, by which they are ex- 
cited, does not exist in a disengaged state in the muscles and 
nerves, previously to the application of metals. Should it be 
urged against this conclusion, that, since metals are much 
better conductors of electricity than moist substances, the 
charge of a muscle may be too weak to force its way through 
the latter, though it may be able to pass along the former; my 
answer is, that, in all Mr. Galvani's experiments, the nerve 
makes a part of the connecting medium between the two sur- 
faces of the muscle, and that the power of no compound con- 
ductor can be greater than that of the worst conducting sub- 
stance, which constitutes a part of it. 
It may be said, however, that, although there is no proof 
that any influence naturally resides in the nerves or muscles, 
capable of producing the effects mentioned by Mr. Galvani, 
these substances may still, by some power independent of the 
properties they possess in common with dead matter, contribute 
to the excitement of the influence, which is so well known to 
exist in them, after a certain application of metals. Before I en- 
ter upon the discussion of this supposition, I must observe, that 
there are two cases of such an application of metals ; the first is, 
when we employ only one metal ; the second, when we employ 
two or more. With respect to the first case, a late author. Dr. 
F owler, who seems to have made many experiments relative 
to this point, positively asserts, that he never saw a fair in- 
