It happened that the wife of Galvani, who was consumptive, was advised
to take as an article of food some soup made of the flesh of frogs.
Several of these creatures were killed and skinned, and were lying on
the table in the laboratory close to an electrical machine, with which
a pupil of the professor was making experiments. While the machine
was in action, he chanced to touch the bare nerve of the leg of one
of the frogs with the blade of the knife that he had in his hand,
when suddenly the whole limb was thrown into violent convulsions.
Galvani was not present when this occurred; but being informed of it,
he immediately set himself to investigate the cause. He found that it
was only when a spark was drawn from the prime conductor, and when the
knife or any other good conductor was in contact with the nerve, that
the contracting took place; and after a time he discovered that the
effect was independent of the electrical machine, and might be equally
well produced by making a metallic communication between the outside
muscle and the crural nerve.