Luigi Galvani and his wife Lucia demonstrating contractions of the muscles of the leg of a frog caused by electrical stimulation. The phenomenon was first noticed when his assistant touched an exposed nerve of the frog with a metal scalpel just as an electrostatic generator was emitting sparks. Galvani's wife and collaborator Lucia Galvani Galeazzi assisted her husband in his work. It is said that she first observed this phenomenon whilst he was in another room and alerted him to this strange occurrence. Galvani's theory of 'animal electricity' was disputed by Alessandro Volta who suggested the electricity was produced by the conjunction of two dissimilar metals.