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 kind of metal; and he advanced the hypothesis that the convulsions are caused by the transport of a peculiar fluid from the nerves to the muscles, the are acting as a conductor. To this fluid the names Galvonism and Animal Electricity were soon generally applied. Galvani himself considered it to be the same as the ordinary electric fluid, and, indeed, regarded the entire phenomenon as similar to the discharge of a Leyden jar.

The publication of Galvani's views soon engaged the attention of the learned world, and gave rise to an animated controversy between those who supported Galvani's own view, those who believed galvanism to be a fluid distinct from ordinary electricity, and a third school who altogether refused to attribute the effects to a supposed fluid contained in the nervous system. The leader of the last-named party was Alessandro Volta (b. 1745, d. 1827), Professor of Natural Philosophy in the University of Pavia, who in 1792 put forward the view that the stimulus in Galvani's experiment is derived essentially from the connexion of two different metals by a moist body. “The metals used in the experiments, being applied to the moist bodies of animals, can by themselves, and of their proper virtue, excite and dislodge the electric fluid from its state of rest; so that the organs of the animal act only passively." At first he inclined to combine this theory of metallic stimulus with a certain degree of belief in such a fluid as Galvani had supposed, but after the end of 1793 he denied the existence of animal electricity altogether.

From this standpoint Volta continued his experiments and worked out his theory. The following quotation from a letter which he wrote later to Gren, the editor of the Neues Journal d. Physik, sets forth his view in a more developed form:—

“The contact of different conductors, particularly the metallic, including pyrites and other minerals, as well as charcoal, which I call dry conductors, or of the first class, with moist conductors, or conductors of the second class, agitates or disturbs the electric fluid, or gives it a certain impulse. Do not ask in what manner: it is enough that it is a principle, and a general principle. This