paragraph_text: mini|desno|300px|[[Luigi Galvani je otkrio 1784. da se preparirani žablji mišići trzaju ako su u dodiru s dvjema različitim kovinama.<ref>David Ames Wells, The science of common things: a familiar explanation of the first principles of physical science. For schools, families, and young students., Publisher Ivison, Phinney, Blakeman, 1859, 323 pages (page 290)]]