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

the electric pile of his, then in use. Bat what interests us par- ticularly, says De la Rive, is the curious fact, that the instant the contact is made with the body, there is a shock ; or if with the galvanometer, there is that instant forwarded a powerful deflection; which is again repeated, though in a less degree, at the moment of disconnecting the circuit;—provided, always, that the other end of the galvanometer and current is in con- nection with the earth. " Here, then" he observes, " vms a closing- and opening- convulsion, much like that observed in the human organism." But we do not, we cannot conclude that they are alike. Volta's hypothetical " counter-current" has been fairly dis- proved by Marianini, who most carefully investigated the whole subject of opening and closing convulsions. He showed that the contraction which takes place at the moment of the closing of the galvanic stream, and that which takes place at its open- ing or cessation, have not the same intensity; at least, this is more visible when the nerve has lost a portion of its excitability ; and that one or other of the twitchings is the more powerful, according to the direction the electric stream is made to traverse the nerve in respect to its ramification. To illustrate this dif- ference as he did, and at the same time to observe some other important physiological facts, we can have recourse to the pre- pared thighs of a frog, which will as well answer for this trial. Only let the thighs of a recently-killed frog be attached to the body, or to the lumbar vetebra? simply by the lumbar nerves. Into a cup of water plunge the feet and legs, while into another cup of water the lumbar portion of the pendulous nerves is caused to be immersed. When thus placed, plunge the posi- tive electrode of a gentle current into the cup that contains the lumbar nerves, and all is prepared to observe the result. Now, if the negative electrode or pole of a battery is suddenly plunged into the cup of water that contains the feet, the mus- cles contract every time it is so done, which, of course, is at the closing of the circuit; but the contraction is not seen on with- drawing the pole, which, of course, opens the circuit; but on changing the place of the poles, — i. e., reversing them in the