According to popular legend, Galvani discovered the effects of electricity on muscle tissue when investigating an unrelated phenomenon which required skinned frogs in the 1780s and 1790s. His assistant is claimed to have accidentally touched a scalpel to the sciatic nerve of the frog and this resulted in a spark and animation of its legs. This was building on the theories of Giovanni Battista Beccaria, Felice Fontana, Leopoldo Marco Antonio Caldani, and . Galvani was investigating the effects of distant atmospheric electricity (lightning) on prepared frog legs when he discovered the legs convulsed not only when lightning struck but also when he pressed the brass hooks attached to the frogs spinal cord to the iron railing they were suspended from. In his laboratory, Galvani later discovered that he could replicate this phenomenon by touching metal electrodes of brass connected to the frogs spinal cord to an iron plate. He concluded that this was proof of "animal electricity," the electric power which animated living things.