In my third memoir upon Induced Contractions, published in the Philosophical Transactions for 1845, at p. 303, after having discussed at length the various hypotheses which appear to offer an explanation of this phenomenon, I was led to conclude that it was due to nervous influence acting through the muscle during contraction; that, in a word, it was to be referred to a kind of nervous induction. In effect, I detailed a number of experiments in that memoir, which prove that there is never any manifestation of the signs of an electric current during the contraction of the muscles; thus in exciting contractions in one of my piles composed of muscular elements, in which the circuit was completed by the galvanometer, the signs of the muscular current were never perceived to increase. Finally, I have shown that the induced contraction is propagated through a coating of turpentine, which is of a nature sufficiently insulating to arrest the passage of any electric current. I was therefore warranted in deducing from these phenomena that in the muscles which contracted, and so produced the induced contractions, there was never any electric current generated, and that therefore the induced contraction could not be explained by a reference to any such agency.
A Case ofTumour in the Brain, with Remarks on the Propagation of Nervous Influence