Figure 1.

Luigi Galvani and the prepared frog next to the spark experiment. A prepared frog consisted of both the lower limbs with the internal crural nerves exposed from the spinal cord level, and a metal wire was inserted across the vertebral canal and positioned a distance away from a charged electrical machine. The frog’s legs contracted powerfully when an assistant of Galvani, most likely his wife Lucia Galeazzi Galvani, accidentally touched the internal crucal nerves with a lancet. In the meantime, a spark was observed from the nearby electrical machine. This observation led Galvani to study animal electricity.