Popular Science Monthly/Volume 41/July 1892/Sketch of Luigi Galvani

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Popular Science Monthly Volume 41 July 1892  (1892) 
Sketch of Luigi Galvani
 

SKETCH OF LUIGI GALVANI.

THE experiments of Galvani were the beginning of a new course of development in physical science, the fruits of which promise to be infinite in number and of incalculable magnitude and importance.

Luigi Galvani was born in Bologna, Italy, September 9, 1737, and died in the same place, December 4, 1798. He exhibited when very young a fervent zeal for the Catholic religion, of which he was exact in observing the most minute rites. He even thought of going into a monastery, but was diverted from his intention, and, while his religious inclinations were still prominently marked, he became interested in scientific pursuits. Entering upon the study of medicine, he gave his attention chiefly to anatomy and physiology — human and comparative. Having successfully maintained a thesis on the Bones, their Nature and Formation, he was appointed, in 1762, public lecturer on anatomy at the University of Bologna, where he became known as a skillful and accurate teacher, though not eloquent in address. Along with his professorship he gained high repute as a surgeon and childbed doctor. He produced during the earlier period of his professional career a number of memoirs of considerable merit, SKETCH OF LUIGI GALVANI. 409

among the most important of which were those on the urinary organs and kidneys of birds and on the ears of birds. In the former paper he treated the subject with remarkable accuracy, showing the position of the kidneys of birds in the abdomen, their situation with respect to the vertebral column, and how they are adapted, as in quadrupeds, to the secretion of urine. The descriptions, all drawn with equal care, contained various curious facts, some of which had then the merit of novelty. Three years after this Galvani had prepared a large work em- bodying the fruits of his studies of the organ of hearing, when he was anticipated by the publication of Scarpa's Observations on the Fenestra Rotunda. He was astonished to find in this book the facts which he had announced at special sessions of the in- stitute, and which he had believed to be his own exclusively, and, giving up the publication of the larger book, satisfied him- self with imparting in a short sketch such facts as were not mentioned in Scarpa's treatise. He gave interesting details re- specting the chord of the tympanum, the membranous labyrinth, the semicircular canals, and on the single little bone which in its own body and appendices performed the functions of the three little bones found in the ears of mammals. His most important work, the one on which his enduring fame is based, was pub- lished in 1791, under the title De Viribus Electricitatis in Motu Musculari Commentarius, or Commentary on the Forces of Electricity in Muscular Motion. It embodied, in a small volume of only fifty-five pages, the account of his experiments with the frog's leg, in which the kind of electrical manifestation to which Galvani's name is attached (galvanism) was first remarked by him. Previous to the publication of this little book Galvani suffered his greatest grief by the death of his wife, Lucie Galeazzi, with whom he had lived happily for thirty years, and who, according to some of the versions of the story, had no little to do with his great discovery. This loss was followed by other troubles, which, although they did not so nearly touch his heart, were severe enough, and eventually perhaps hastened his death. The Cisal- pine Republic required an oath from all persons in its service, which, it being repugnant to his political and religious convic- tions, Galvani refused to take. The Government deprived him of his position, and he, nearly reduced to poverty, went to live with his brother Giacomo. Soon afterward he fell into a decline, from which he could not be raised even by the skill and careful attention of the eminent physicians Uttini and Cingari. The Government of the republic, recognizing the eminent worth of his scientific achievements, notwithstanding he persisted in refusing to take the oath, ordered him restored to his chair in the univer- sity, but he never took advantage of the act.

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Various stories are told of the manner in which Galvani's dis- covery of galvanic action, or " animal electricity," as he called it, was brought about. According to one version, he was preparing a frog-broth for his invalid wife, and some skinned frogs were lying on a table by the side of an electrical machine. One of his assistants accidentally touched the crural nerve of one of the frogs with the point of a scalpel, when all the muscles of the limbs seemed to be taken with strong spasms. Madame Galvani, a bright, thoughtful woman, who was present and witnessed the shock, was struck with the novelty of the phenomenon, and thought that she noticed along with it a disengagement of the electric spark. She informed her husband at once, and he lost no time in verifying the extraordinary fact. The point of the scalpel being again applied to the frog, while a spark was drawn from the ma- chine, the contractions were resumed. To determine whether they were not due to the simple contact of the scalpel, Galvani touched the same nerves of other frogs without turning the machine, and got no contractions. Repetitions of the experiments were accom- panied with corresponding results. Another account makes Gal- vani himself the chief actor in the incident ; while, according to a third account, Galvani, having dissected some frogs, in a study of their nervous system, hung them on an iron railing with a copper hook thrust in their lumbar nerves, and the contractions took place whenever, in the vibration of the specimens, these nerves touched the iron too. According to the documents in the possession of the Museum of Bologna, the discovery was not all a matter of accident, as these stories would make it appear, for it is shown there that Galvani had been engaged, for twenty years before the publication of his Commentary, in investigations of the action of electricity on the muscles of frogs. The thought in- volved in these experiments had also been more or less vaguely suggested by other writers. Sulzer, in his Nouvelle Thdorie du Plaisir, published in 1767, had spoken of the peculiar taste pro- duced when two pieces of different metals were put, under certain precautions, into the mouth. A pupil of Cotugno, Professor of Medicine at Naples, in dissecting a mouse about 1786, perceived a movement at the moment when his scalpel touched one of the animal's nerves. Galvani described his experiments, and claimed that he had discovered a kind of electricity having remarkable peculiarities, in the Commentary (De Viribus Electricitatis in Motu Musculari) already mentioned, which was published in 1791 and 1792. One of the immediate results of his discovery was the invention of his metallic arc, the first experiment with which is described in the third part of the Commentary, with the date September 20, 1786. This arc was constructed of two different metals, which, placed in contact, one with a nerve and

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the other with a muscle of a frog, caused contraction of the muscle.

Galvani recognized a great similarity between the phenomena he had observed and electricity, but denied their identity. He thought an electricity of a peculiar nature was concerned in the manifestations, and that he had discovered the nervous fluid. In his view, all animals possessed an electricity inherent in their economy, which resided especially in the nerves, and was com- municated by them to the whole body. It was secreted by the brain ; the interior substance of the nerves was endowed with a conducting power for this electricity, and facilitated its move- ment and its passage through the nerves ; at the same time an oily coating of these organs prevented the dissipation of the fluid and facilitated its accumulation. The principal reservoirs of this electricity he supposed to be in the muscles, each fiber of them representing a small Leyden jar, from which the nerves were con- ductors. In the mechanism of the movements the electric fluid was drawn out and attracted from the interior of the muscles into the nerves in such a way that each discharge of the muscular electric jar corresponded with a contraction of the muscle. This theory had many partisans for a considerable time, but was re- futed by Volta, who showed, as has been related in our recent sketch of him, that the supposed nervous fluid was only ordinary electricity, to which the animal organs served as conductors, and of which they might even be generators. Galvani did not yield to these arguments of Volta's, but held to his own unsound hy- pothesis ; and thus the glory of making a scientific explanation and application of his great discovery fell to Volta. An account of Galvani's discoveries was published in the Philosophical Trans- actions for 1793. A quarto edition of his works was published at Bologna by the Academy of Sciences of the Institute of that city in 1841-'42. Perhaps the best and most appreciative accounts of Galvani's life and works are by M. Arago, in Alexandre Volta, in the first volume of Arago's CEuvres Completes, and the eulogy by J. L. Alibert, Bologna, 1802.

��Mr. A. Wilkins, of Tashkend, central Asia, had a specimen of the typical desert hird of the country (Podoces panceri), which, on the first day of its life with him, buried a part of the food given it in the sand with which the floor of the cage was covered. On the next day, and afterward, the bird abandoned the habit on perceiving that the supply given it did not fail. Another correspondent of Nature had a fox-terrier puppy, seven weeks old, which had not seen any other dog but its mother, that buried bones in the garden with great skill. It dug a hole with its fore paws, put in the bone, pushed it down with its nose, and cov- ered it with garden soil which was pushed in with its nose. He had never seen so young a puppy bury bones, or any other dog do it so well.

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