Electro-physiology and electro-therapeutics : showing the best methods for the medical uses of electricity / By Alfred C. Garratt.
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is negative. The quantity of electricity liberated in any of these fishes is found to be in direct proportion to the energy of its circulation and respiration. They can effect their discharges in the air, as in the water; for, if held in the hands, the shocks are so intense and succeed so rapidly, that it is impos- sible for most persons to endure it. But then the fish soon becomes weary, and it is necessary to replace it in its native element of fresh or salt water, and allow it to have a long rest, as well as nourishment, to enable it to regain its accustomed power for shocks. We must readily see the resemblance be- tween this arrangement of nature and the artificial voltaic pile; indeed, the electric organs of all these animals constitute veri- table, as visible, living voltaic piles, without metals, it is true, but possessing the arrangement of positive and negative sur- faces, as if Volta himself had copied them, or they had been con- structed on the voltaic plan. Professor Colladon has still more recently observed, by a cap- ital experiment directed to that end, a very instructive fact, which, it is true, M. Matteucci and others had observed in a less direct manner. He placed the two terminal platinum electrodes of a very delicate galvanometer, the one to the under surface of the torpedo, and the other to its upper surface, imme- diately after the fish had been exhausted by the effects of re- peated excitations and discharges. He then wounded the fish, by cutting deep and successive gashes in its flesh. These gave no results. Next he thrust the point of his penknife into the substance of the cerebellum of the torpedo, when he instantly saw the galvanometer needle fly completely around. This ex- periment he repeated, by using a sharp point of ivory, in a fresh torpedo; and this was attended with exactly the same results, which prove conclusively the large influence of the living brain and nerves, in producing the development of tangible electricity in these fishes. That the electric power of the Suri- nam eel resides in the brain, was first proved by Baron Alexan- der von Humboldt. Father Linari, it is said, has succeeded in producing veritable electric sparks between the surface of some quicksilver that communicated by means of a conducting wire