Frogs and Animal Electricity

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.

Instruments as Frogs: the Leyden Jar and Voltaic Pile

By the late 18th century, natural philosophers knew that electricity could stimulate muscular motion. What kind of electricity was it, though, and how was it produced? To answer this question, Galvani and Volta each pointed to an instrument used for storing or producing electric current whose operation was more convincingly understood than the frog's kick: Galvani said the frog's leg works like a Leyden jar, and Volta compared it to his own, new invention, the battery pile.

When Galvani hung a frog's leg over his iron banister and saw it kick, a familiar electrical instrument came to mind:

"These results surprised us greatly and led us to suspect that the electricity was inherent in the animal itself. An observation that a kind of circuit of a delicate nerve fluid is made from the nerves to the muscles when the phenomenon of contractions is produced, similar to the electric circuit which is completed in a Leyden jar, strengthened this suspicion and our surprise." (1)

The electrical nature of muscular motion that Galvani and Volta investigated did not only spur further physiological research, but also provided foundations for innovative medical therapies.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.

The Whipple Museum's Electro-Galvanic Machine was built in the late 19th century (likely between 1886 and 1893) by Horne, Thornwaite, and Wood at 123 Newgate Street London, where they ran an instrument company. Ironically, perhaps, given their inventors' disagreements, the Galvanometer was powered by a voltaic pile. Metal electrodes channelled current through specific contact points on the body, each selected for a precise medical purpose.

Covering the lid's inside surface is a pamphlet on "Administering Medical Galvanism". Scientific studies on the medical uses of Galvanism proliferated in the second half of the 19th century. They claimed, for its uses, the healing of paralysis and other disorders related to the nervous stimulation of muscles. Some used Galvanian stimuli to treat hoarseness, ocular distortions apparently due to anemia, asthma, and constipation. Several obstetricians tried to induce and facilitate labour by administering shocks to pregnant women, which usually met with tragic results.