Frogs and Animal Electricity

In the late 18th century, frogs were the talk of the Italian scientific establishment. Two prominent experimentalists, Luigi Galvani and Alessandro Volta, presented novel theories of animal and chemical electricity that they attempted to defend by reference to scientific instruments. At issue was the nature of nervous response and muscular motion in the frog. The Whipple Museum's voltaic piles, Leyden jars, and electro-galvanic machine embody distinct interpretations of the frog's ambiguous body.

In the 1780s, the Bolognese physician Luigi Galvani (1737-1798) conducted a vast range of experiments on electricity's effect on "prepared" frog specimens - that is, frog legs severed at the base of the spine, with nerves exposed. These studies culminated in his Commentary on the electrical force of muscular motion of 1791, which quickly seized the attention of the physical scientist and Galvani's eventual rival, Alessandro Volta (1745-1827).

Galvani's first crucial result in his frog experiments was the product of good fortune: while investigating the effect of atmospheric electricity on "prepared" specimens, Galvani and his assistants hung frog legs from an iron railing, with brass hooks dangling from their spinal nerves. One hook touched the railing, and the attached frog's leg kicked. Placing the legs and hooks on other metals and doing the same had a similar effect, but nothing happened when they placed the frog on non-conducting materials like wood, glass, or resin.

Galvani and Volta argued over the frog's kick for years. Each justified his position by comparing the frog to a scientific instrument - Galvani said the frog's leg works like a Leyden jar, and Volta compared it to his own, new invention, the battery pile.

» Instruments as frogs: the Leyden Jar and Voltaic Pile.

19th century physicians and scientists applied Galvani's model of the frog's muscular motion, which he considered the product of carefully balanced and imbalanced electrical currents, to new forms of medical therapy, which they called "Galvanism." Electrical medicine gave rise to new machines and new types of treatment.

» Electro-galvanic machine.

Henry Schmidt

Henry Schmidt, 'Frogs and Animal Electricity', Explore Whipple Collections, Whipple Museum of the History of Science, University of Cambridge, [http://www.hps.cam.ac.uk/whipple/explore/frogs/animalelectricity/, accessed 25 November 2017]

 
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