The Galvani-Volta controversy

5. The third experiment and Volta's reaction
In 1794 Galvanians produced further proof of animal electricity. They showed that spasms could occur simple when there was contact between the crural nerves and the frog’s leg muscles. Even if Galvani seemed to have won at this point, Volta refused to give in. He observed that Galvanian experiments required the presence of saliva or blood in the nerve-muscle contact. This led him to think that even second-class conductors could generate electricity.
“They (the experiments) simply show that I have been precocious in asserting that it was impossible to make the frog twitch merely by applying moistened conductors, without any other intervention to excite the frog’s convulsions… It is the difference between the conductors that is necessary, whether they are metallic or moistened.”