Luigi Galvani

Italian physician and physicist

• Born: September 9, 1737
• Birthplace: Bologna, Papal States (now in Italy)
• Died: December 4, 1798
• Place of death: Bologna, Cisalpine Republic (now in Italy)

Galvani contributed to physiological studies on the electrical stimulation of nerves and muscles. His most important discovery was the production of electric current from the contact of two different metals attached to a frog, which led to the invention by Alessandro Volta of the electric battery.

Early Life

Luigi Galvani (lew-EE-jee gahl-VAH-nee) was born on the via de’ Maggi in Bologna. He was the third of four children born to Domenico and Barbara Foschi Galvani and was baptized Alyosio Domenico. His family was well known in Bologna, going back in local records to 1267. Deciding early to pursue a medical career, he entered the University of Bologna, where he studied philosophy and medicine under some of the leading teachers of his time.

Under Domenico Galeazzi, Galvani developed a special interest in anatomy. After receiving his degree in medicine and philosophy in July, 1759, he wrote his doctoral thesis on the structure, function, and pathology of the human skeleton. He described human bones, their anatomical and chemical composition, their growth patterns, and their diseases.

In 1762, Galvani married Lucia Galeazzi, the only daughter of his teacher. Professor Galeazzi had served four terms as president of the Bologna Academy of Science. For several years, Galvani served as an honorary lecturer in anatomy at the University of Bologna and as an instructor at the affiliated Institute of Science while maintaining a medical and surgical practice and conducting anatomical research. He was installed by the Senate of Bologna in 1766 as curator of the anatomical museum at the university. In 1768, he became a paid lecturer, and in 1773 he was promoted to the rank of professor of anatomy and surgery. His demonstrations made his lectures popular, though he was not regarded as an eloquent lecturer.

Galvani’s early research efforts were devoted mostly to bird anatomy. He published an article on the kidneys of birds in 1767 that described the three-layered ureteral wall and its peristaltic and antiperistaltic movements (contractions) when irritated. He also devoted several papers to the anatomy of the ear in birds. When Galeazzi died in 1775, Galvani succeeded him as lecturer in anatomy, having already succeeded him as president of the academy in 1772. Finally, in 1782, the Senate of Bologna elected him professor of obstetric arts at the Institute of Science.

Life’s Work

Galvani’s most important work began in the 1770’s with a shift in emphasis from anatomical concerns to physiological studies on nerves and muscles in frogs, leading to a particular interest in animal electricity. In 1772, he presented a paper to the Institute of Science concerning the Swiss physician Albrecht von Haller’s theory of irritability. Haller had demonstrated muscle contractions by stimulating muscle and nerve tissues. Galvani presented two more papers to the institute in 1773 and 1774 on muscle movements in frogs and on the effect of opiates on frog nerves. These studies led him to conduct a series of experiments in the late 1770’s on electrophysiology; he stimulated frog muscles by electrical means.

Earlier work on animal electricity had been done by several other Italian researchers. Electricity had been used to stimulate muscles in 1756 at Bologna, and it had been suggested that nerves conduct a so-called electric fluid and perhaps even excite it. Giambattista Beccaria, professor of physics at the University of Turin, used electricity to stimulate the muscles of a living rooster and published correspondence on his electrical research that supported and extended the ideas of Benjamin Franklin on atmospheric electricity.

By 1780, Galvani had acquired an electrostatic machine and a Leyden jar for producing and storing electric fluid, and after 1783 his major field of research became animal electricity. He prepared frogs for electrical stimulation by dissecting the lower limbs as a unit with the spinal column attached by the crural nerves (the nerves that act on the leg muscles). By touching the conductor of his electrostatic machine to the spinal cord resting on a pane of glass, he could observe the contractions of the muscles in the legs when the machine was discharged. Galvani also experimented with the effects of atmospheric electricity on warm-blooded animals, assisted by his nephew Camillo Galvani. In September, 1786, he recorded a frog-muscle contraction when the nerve was touched by scissors during an electrical storm.

In autumn of 1786, Galvani began to observe some surprising phenomena that led to his discovery of current electricity in contrast to the static electricity used in his experiments. These observations started when an assistant touched a scalpel to the medial crural nerve of a frog preparation and observed violent contractions even though the electrostatic machine was disconnected and at some distance away on the table. Another assistant—his wife, Lucia, according to some accounts—noticed that this happened at the same moment that a spark was discharged from the electrical machine. Galvani confirmed this effect with several experiments in which contractions were induced whenever the nerve was touched by a grounded conductor at the same time that a spark was drawn from a disconnected electrical machine.

To see if this induction effect would result from natural electricity, Galvani fastened some prepared frogs by brass hooks in their spinal cord to an iron railing surrounding a balcony of his house and observed contractions when lightning flashed. The most surprising result was that contractions continued to occur even after the sky cleared, and these were intensified when the brass hook in the spinal cord was pressed against the iron railing. At first, Galvani viewed the frog preparation as a sensitive electroscope, but then he suggested that perhaps electric fluid was produced within the assembly of frog and metals, independent of any external electrical source.

Galvani confirmed this result indoors by placing the frog preparation on an iron plate and pressing the brass hook against it. He found that the strength of the contractions depended on the kinds of metals used and that nonmetals such as glass and resin produced no effect. He also performed a series of experiments in which metallic arcs were connected between the leg muscles and the hook in the spinal cord and again showed that the kinds of metals in the arc and hook determined the strength of the contractions. Thus, Galvani clearly demonstrated the main features of what came to be known as “galvanism” by producing an electric current from the contact of two dissimilar metals in a moist environment. He thought, however, that this environment must include animal tissues and that they were the source of the electricity. Thus, he believed that he had confirmed the existence of “animal electricity,” which some thinkers in the eighteenth century believed to be a vital force, separate and distinct from other, inorganic forms of electricity such as lightning or static electricity.

After five years of careful research, Galvani published the results of his work, De viribus electricitatis in motu musculari commentarius (1791; Commentary on the Effect of Electricity on Muscular Motion, 1953). This four-part essay reviewed the effects of artificial electricity on muscular motion, similar effects produced by atmospheric electricity, his observations and ideas in support of animal electricity, and his final conclusions and conjectures. In the last section, he asserted that the muscle was like a Leyden jar in which the nerve becomes positively charged while the muscle becomes negatively charged: A metal simultaneously contacting both nerve and muscle would cause a discharge of electric fluid, which in turn would account for the contractions he had observed in his experiments.

Galvani’s Commentary on the Effect of Electricity on Muscular Motion aroused considerable interest among scientists, and his experiments were repeated by many. Alessandro Volta, professor of physics at the University of Pavia and already famous for his work in electricity, pursued the theory of animal electricity but became skeptical after it occurred to him that the metals might be the source of the electric fluid, with the frog legs serving only as a kind of electroscope. By the end of 1793, Volta had rejected animal electricity in favor of his “contact” theory, in which electric fluids were produced by the mere contact of two dissimilar metals.

A long debate followed from these two interpretations, leading to many ingenious experiments being conducted by both Galvani and Volta. Galvani showed that contractions resulted from two pieces of the same metal, which Volta explained by differences in metal composition. Much of Galvani’s defense was continued by his nephew Giovanni Aldini, son of his sister Caterina and later professor of physics at Bologna. The controversy spread: Other scholars at Bologna disagreed with those at Pavia; physiologists argued against physicists, and animalists argued against metalists. Despite their differences, Galvani and Volta remained on friendly terms.

In the last years of his life, Galvani suffered many difficulties, but he managed to continue his work. His wife died childless in 1790 at the age of forty-seven. In 1794 and 1797, he announced two experiments in which contractions were produced merely by touching frog nerves to muscles without any metals. During this time, he made a sea voyage along the Italian coast to collect marine torpedoes and showed that their strong electrical discharge was generated by structures similar to nerves and muscles. Although these results supported Galvani’s theory of animal electricity, they also led Volta to invent the bimetallic pile (electric battery) in 1799. Galvani died in the house of his birth the year before Volta’s invention. Earlier that year, he was dismissed from the university and lost his salary when he refused to take an atheistic oath of allegiance to the Cisalpine Republic created by Napoleon I. He left his microscope to Aldini, his electrical machine to his nephew Ludovico Galvani, and his manuscripts to another nephew, Camillo Galvani.

Significance

Luigi Galvani was a modest and deeply religious man whose achievements were the result of hard work and careful experimentation. His many contributions are often obscured by Volta’s discovery of a source of constant electric current, which ushered in the electrical revolution of the nineteenth century; Galvani, however, provided the generative spark that made Volta’s discovery possible. Moreover, his early contributions to the pathology of bones and the comparative anatomy of birds alone would have been sufficient to secure his reputation. His investigations of birds’ ears included many original and valuable observations.

All of Galvani’s writings demonstrate the thoroughness of his scientific method, but this is especially true of those concerning his electrical experiments. His observations of electrostatic induction, including the inductive effects of lightning discharges on his frog preparations, anticipated the discovery of the propagation of radio waves. His most important contribution, however, was his observation and description of the production of electric fluid from the contact of two metals with frog muscles. These experiments led directly to the investigations by Volta of what he called “galvanism” and the invention of the electric battery. Thus, Galvani’s name has been immortalized in words such as “galvanometer” and “galvanize.”

The publication of Galvani’s Commentary on the Effect of Electricity on Muscular Motion and the subsequent Galvani-Volta debate stimulated much further research in both physics and physiology. Although Galvani failed to see the full significance of his discovery of galvanism, he demonstrated the electrical nature of the nervous fluid. His defense of animal electricity led to experiments that in effect marked the beginning of electrophysiology as a science. His demonstrations that frog leg contractions resulted from contact between nerve and muscle even without metals led to the discovery in the 1840’s of the electrical nature of nerve impulses by Emil Du Bois-Reymond and others. The life and work of Luigi Galvani are too important to be dismissed as merely a confused preface to the discovery of methods to produce electric current and the electrical revolution that followed.

Bibliography

Dibner, Bern. Galvani-Volta: A Controversy That Led to the Discovery of Useful Electricity. Norwalk, Conn.: Burndy Library, 1952. Contains a brief description of the historical background and scientific work of Galvani, the defense of his ideas by Aldini, and the controversy with Volta, as well as an original translation of the first experiment establishing the existence of electricity in living tissues, published anonymously in 1794.

Fara, Patricia. An Enlightenment for Angels: Electricity in the Enlightenment. Lanham, Md.: Totem Books, 2002. Provides brief explanations of experiments conducted by Galvani, Volta, Benjamin Franklin, and other seventeenth and eighteenth century scientists who studied electricity.

Galvani, Luigi. Commentary on the Effect of Electricity on Muscular Motion. Translated by Robert Montraville Green. Baltimore: Waverly Press, 1953. The twelve-page introduction discusses and evaluates Galvani’s life and work. Includes an original work by Aldini. Also translated by Margaret Foley for Burndy Library in 1953.

Keithley, Joseph F. The Story of Electrical and Magnetic Measurements: From 500 B.C. to the 1940’s. New York: IEEE Press, 1999. Historical survey of significant discoveries regarding electricity and magnetism. Chapter 10 outlines Galvani’s experiments with frog legs.

Lenard, Philipp. “Luigi Galvani and Alessandro Volta.” In Great Men of Science: A History of Scientific Progress. New York: Macmillan, 1933. This twelve-page chapter gives a brief account of the life and work of Galvani and the development of his work by Volta.

Pera, Marcello. The Ambiguous Frog: The Galvani-Volta Controversy on Animal Electricity. Translated by Jonathan Mandelbaum. Princeton, N.J.: Princeton University Press, 1992. Recounts how the two scientists offered different theories to explain why a dead frog’s muscles contracted when stimulated by electricity. Pera describes theories of electricity in the 1790’s, and compares the careers and laboratory procedures of Galvani and Volta.

Potamian, Michael, and James Walsh. “Galvani, Discoverer of Animal Electricity.” In Makers of Electricity. New York: Fordham University Press, 1909. This twenty-nine-page chapter gives an interesting and readable account of Galvani’s life and work, though it contains some historical inaccuracies.