. Electro-physiology. Electrophysiology. XI ELECTRICAL FISHES 411 (4 g, h) finally decided on the arrangement shown in Fig. 268, as the most convenient for leading off from the torpedo in water. A circular zinc-plate, covered with flannel, about the same size as the body (v vj, was placed at the bottom of a glass vessel 30 cm. wide and 10 cm. deep. A portion of the zinc was bent outwards for leading off. The fish lay upon the flannel. The dorsal shield, for leading off from the back, is again a zinc-plate shaped to the fish with the edge turned up; the upper surface is lacquered, and a wooden
. Electro-physiology. Electrophysiology. XI ELECTRICAL FISHES 411 (4 g, h) finally decided on the arrangement shown in Fig. 268, as the most convenient for leading off from the torpedo in water. A circular zinc-plate, covered with flannel, about the same size as the body (v vj, was placed at the bottom of a glass vessel 30 cm. wide and 10 cm. deep. A portion of the zinc was bent outwards for leading off. The fish lay upon the flannel. The dorsal shield, for leading off from the back, is again a zinc-plate shaped to the fish with the edge turned up; the upper surface is lacquered, and a wooden knob in the middle carries the second wire for leading off. By this method it is easy to lead off the shock, and to experiment without injuring the animal. A valuable instru- ment, with many applications, is the nerve-muscle preparation. FIG. it>i;. Fit;. -T'7. of a frog, employed as early as 1797 by Galvani, and later again by Matteucci, in experiments on Torpedo. Du Bois-Eeymond constructed the so-called "frog-alarum" (Fig. 268, FW), by lead- ing off part of the discharge that was passing through the water containing the fish, by means of a pair of submerged electrodes, to the nerve of a rheoscopic leg, the muscle of which rang a bell when it contracted, and thus indicated the successive dis- charges of the organ. In this way the electrical activity of a fish under water can be observed with little trouble and absolute certainty for hours at a time. Schonlein (30) has recently employed the telephone for the same purpose, with very good results. He connected one end of it with a lead plate lying 011 the floor of the fish-trough, while the wire from the other pole ended in a smaller lead plate, that dipped into the water. Even in weak animals (Torpedo}. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original w
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