Luigi Galvani demonstrating the contraction of the muscles in the leg of a frog.He first observed the twitching and contraction of a frog's leg when two different metals were placed on its spinal cord and the muscles of the leg. He went on to use a bimetallic arc consisting of copper and zinc to carry out further experiments. He ascribed the effect to \animal electricity\" whereas Volta attributed the contraction to the electrochemical behaviour of two dissimilar metals in a bimetallic arc which were in contact with electrolytes in the frog's tissue."