. Animal physiology. Physiology, Comparative. 342 ELECTRIC FISHES : TORPEDO. excellent food), and to make tlie rivers they infest passable to travellers. A number of wild horses are collected in the neighbourhood, and are driven into the water; the Gymnoti attack these, and speedily stun them, or even destroy their lives by repeated shocks; but their own powers of defence and injury are exhausted in the same degree, and they then become an easy prey to their captors. 4:21. The shock of the Torpedo (fig. 177) is less powerful; but it is sufficient to benumb the hand that touches it. From its pr
. Animal physiology. Physiology, Comparative. 342 ELECTRIC FISHES : TORPEDO. excellent food), and to make tlie rivers they infest passable to travellers. A number of wild horses are collected in the neighbourhood, and are driven into the water; the Gymnoti attack these, and speedily stun them, or even destroy their lives by repeated shocks; but their own powers of defence and injury are exhausted in the same degree, and they then become an easy prey to their captors. 4:21. The shock of the Torpedo (fig. 177) is less powerful; but it is sufficient to benumb the hand that touches it. From its proximity to European shores, this fish has been made the subject of observation and experiment more completely than the other; and some curious results have been attained. It seems essential to the proper reception of the shock, that two parts of the body should be touched at the same time ; and that these two should be in different electrical states. The most energetic dis- charge is procured from the Torpedo, by touching its back and belly simultaneously ; the electricity of the back being posi- Fig. ^.^^^ ^^^ ^^^^^ ^^ ^j^^ ^^^jy negative. When two parts of the same surface, at an equal distance from the electric organ, are touched, no effect is produced; but if one be further from it than the other, a discharge occurs. It has been found that, however much a Torpedo is irritated through a single point, no discharge takes place; but the fish makes an effort to bring the border of the other surface in contact with the offending body, through which a shock is then sent. This, indeed, is probably the usual manner in which its dis- charge is effected. If the fish be placed between two plates of metal, the edges of which are in contact, no shock is per- ceived by the hands placed upon them, since the metal is a better conductor than the human body ; but if the plates be separated, and, while they are still in contact with the opposite sides of the body, the hands be ap
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