frog, with nerves attached to the muscles of the legs, rests on a plate of silver (F) with the legs on a
plate of copper (G). When the experimenter connects the two plates with an iron rod, the circuit is
completed, and current flows through the preparation, stimulating the nerves and producing muscle
contraction in the legs. Galvani, of course, believed the source of the current to be in the animal
tissues.
Fig. 1 4. Alessandro Volta, physicist and experimenter. At age 34 Volta became professor of physics at
the university in Pavia, remaining in that post until his retirement 40 years later. Volta had been
elected to the Royal Society in 1791 in recognition of his work on electricity. After Galvani published
his classic paper in that same year, Volta became interested in these observations of his countryman,
duplicated them, made the proper deduction and discovered bimetallic continuous electricity. He
reported these observations in the Transactions of 1793 and in 1800 reported the invention of the
Voltaic Pile, a sample of which stands on the table before him.
Fig. 1.5. The first demonstration of true animal electricity. When the leg of the frog, held in the left
hand, is brought into contact with the exposed spinal cord, the other leg will twitch. This was first
reported in the anonymous paper published in Bologna in 1794. We now know that the muscular
contraction is the result of electrical currents of injury coming from the skinned leg of the frog.
Galvani was not well suited to scientific controversy. His only reply to Volta's attack was to
publish, unfortunately anonymously, a tract reporting several additional experiments in which muscular
contraction was produced without any metal in the circuit. The experiments actually demonstrated the
ELECTROMAGNETISM & LIFE - 13