Electro-physiology and electro-therapeutics : showing the best methods for the medical uses of electricity / By Alfred C. Garratt.

cups, — the effects are found to be just the reverse. This trial proves, then, that the contraction or twitching is caused at the closure of the down-running current, which is with the ramifica- tion of the nerves; but not at the opening, or discontinuing of the up-running stream, i. e., in an opposite or inverse direction to the branching out or ramification of the nerves. Another arrangement of the prepared frog thighs, made by Marianini, proves the same facts, and renders these fundamental results familiar ; and for that reason they are repeatedly shown in this work. The frog is to be prepared as before in Galvani's original method, but arranged now so that one leg shall be placed in each of the two glasses of water. If, then, the poles of a moderate current are quickly plunged into the water of the respective cups, the legs, if from a recently-killed frog, will spring out of the cup ; but if now we forcibly retain them in the cups, and then frequently repeat the closure and opening of the circuit, we shall for a while see twitchings in both legs, and that as well on opening as at closing the circuit. Then, by continuing to operate thus for>a time, the excitability diminishes or exhausts, until we notice that only one of the limbs contract, and that when the current is closed; and this is the limb with the negative pole, and where, of course, the current runs down it. But if the poles are plunged into the water and retained there for a little time, then, on removing them, or one of them, the twitching is seen to take place in the opposite limb, i. c., in that one that is traversed by the current running up it. If the trial is reversed, by exchanging the poles in the cups, and thus causing the current to run up the limb where it had before run down, and vice versa, the result will follow in ac- cordance with the same law, viz., the closing contraction will now be in the limb where before was the opening. Further: if the thighs of two frogs are now prepared, as before described, and the four large nerves are placed in the same glass of water with them, while the flesh of the two legs of the one frog is transfixed by the positive electrode, and the flesh of the two legs of the other frog is similarly arranged with the negative pole then the frog that is at the negative, and