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

His first trials in tliis line, let me repeat, were upon the frog. He cut the frog across in the middle, and then after quickly opening its body, the points of the scissors were passed beneath the two visible lumbar nerves, which are plainly seen lying super- ficially upon the psoas muscles, as the frog lies opened and upon its back, like two white threads. It is well, in preparing the frog for this experiment, to remove two or three of the lower vertebras, and thus the lumbar nerves are left alone as the only connection between the thighs of the hind legs and the upper vertebras of tbe body. If, now, this portion of the frog is quickly and adroitly placed, say suspended to an insulated electrode of a feeble battery by the cut tips of those large nerves, and then the leg muscles are touched by the other insulated electrode,— not insulated from the frog, but from every thing else, — so that a gentle current passes from the nerve to the muscle group of the leg so touched, or to both legs if both are so touched simul- taneously, then the limb or limbs are seen to contract with an extremely sudden and strong twitch. If this trial is made by placing the legs of the frog each in a separate glass of water, and then plunging the electrodes into the water of each, that instant the frog's legs undergo so sudden and violent a contrac- tion, that they are often thrown entirely out of the glasses. It is not necessary to include the whole nerve and muscle in the current to produce this effect; for it is found that a very short portion is sufficient, and that the nearer the upper portion, the greater the effect from the same current. It is said that in 1818, Dr. Ure made some capital trials with electricity on the body of a man who had been hanged, im- mediately after the execution. He expeditiously submitted the fresh body to the action of a galvanic current from two hundred and seventy series of copper and zinc pairs of sixteen square inches of surface each. To reach directly the larger nerve trunks of the but recently dead body, he made incisions into the flesh, so as to place one electrode in actual contact with the spinal marrow, while the other was in immediate contact with the great sciatic nerve. By now closing the circuit, all the limbs of the body were agitated by convulsive movements. Then, again