I first became acquainted with this fact, while making the following experiment. Having laid bare the brain of a living frog, and put a stop to its spontaneous motions, by gently pressing upon the brain, I introduced a long slip of tin-foil doubled underneath a part of the skull, which had not been removed, and placed a silver probe upon its tongue. The only muscles which contracted, when the tin-foil was bent over the nose of the frog, so as to come in contact with the probe, were those which move the eyes, and the transparent membrane which defends them, those of the tongue and of the throat. When the tin-foil was twisted into a thin roll, and passed a little way down the spine, the muscles of the upper extremities and of the thorax contracted; when a little further, those of the back and of the abdomen contracted; and when, introduced still further, to where the sciatic nerves leave the spine, the posterior extremities were, for the first time, strongly convulsed. I have repeated this experiment very frequently; and have always found, that, as soon as the spontaneous motions of frogs had ceased, the contractions, excited by the metals, were uniformly progressive from the head downwards, corresponding exactly to the progress of the metals down the spine. The experiment sometimes succeeds when neither the brain nor the spinal marrow have been laid bare, and when even the skin has not been divided, but, when the frog is placed upon a plate of zinc, and one of the ends of a bent silver wire is placed upon any part of its spine, while the other is made to touch the plate. --------------------- 5. As it has not been till very lately, that I have been able to procure an electropherus, I have as yet made but few experiments with it; their result, however, is such as tends still more to confirm me in the opinion, that the influence, discovered by Galvani, has no relation whatever to electricity.