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

To make this fair and clear, Galvairi would take a frog and first kill it; then quickly skin it; and then, bypassing the point of a pair of sharp scissors beneath the two visible and easily accessible lumbar nerves, which always lie, as can be seen, by opening the abdomen of a frog and pressing the entrails to one side, as they naturally lie superficial for a half inch upon the psoas muscle and anterior to the vertebral column, so that the blades of the scissors embrace all the loins except the nerves; he then cuts again in the same manner a half inch above or below, so as to remove the two or three lower vertebrae, and leave the nerves intact and uninjured, but separate, reaching from the thighs to the body of the frog, suspended in the air like telegraph wires. He would then touch a nerve with one metal, and the muscle of the thigh by another metal, and then, when the outer end of these two metals touched, i. e., were in contact so as to form an arc from nerve to muscle, there was an instant powerful contraction. But as Volta objected, on ac- count of the two metals employed, Galvani used a bit of wire of but one metal, one end of which touched the nerve, while the other was made to touch the muscle, and by this the same instantaneous contraction was produced, but in less degree. But Volta again objected, that however infinitesimal might be the conceivable difference in the homogeneity of the metal arc used for the conductor, it would be sufficient to produce an electric current that might be made perceivable by the delicate test of the contractions of the frog's leg ; for this was indeed not only the most delicate test of electric currents, but it was the only galvanometer then known. M. Galvani then attempted to produce the contractions with- out the employment of any sort of metal, or other foreign sub- stance whatever. He therefore cut off the body from the pro- jecting lumbar nerves, and then let the nerve fall upon the plate of glass upon which several such cut-off legs and nerves lay. He then would raise the nerve carefully with a small glass rod, and bring near and under it another frog's leg, and then let the raised nerve fall or touch gently but a single point on the external surface of the muscle ; and this even produced contrac-