After seven years of teaching, Volta was given the opportunity to visit various parts of Europe, and took advantage of the occasion to meet most of the celebrated men of science. His linguistic faculty stood him in good stead during this sabbatical year, and his travel aided him in completing a thorough acquaintanceship with European languages as well as with scientists. His practical character led him, during his trip, to note the growth of the potato and its uses in various European countries, and he brought the plant home with him to Italy in order to introduce it among the farmers. He succeeded in making his countrymen realize its value, and the introduction of the potato is one of the reasons for which Italians have always looked up to him as a benefactor of his native land. How modern this makes a vegetable we are inclined to think of as having been always an important food resource of the race! About the middle of the third quarter of the eighteenth century, by one of the fortunate accidents that happen, however, only to genius, Galvani, at the time Professor of anatomy in Bologna, had been led to make the observation that if a frog, so prepared that its hind leg is attached to the trunk only by means of the sciatic nerve, happens to be touched by a metal instrument in such a way as to put nerve and muscle in connection with each other through the metal instrument, a very curious phenomenon is observed, the muscles of the almost severed leg becoming spasmodically contracted and then relaxed whenever the contacts were made and broken. Galvani noted the phenomenon first in connection with an electric machine, and looked for an explanation of it in electricity, thinking that there was an analogy between it and the discharge of the Leyden jar. After several years of careful observation, he published a monograph on the subject, which at once attracted attention all over Europe. Volta was very much interested in Galvani's work, and took up the development of it from the physical side. At first he agreed with the explanation offered by Galvani, who considered that his experiment demonstrated the presence of electricity in animal bodies, and who proposed to introduce the term "animal electricity." After careful investigation, however, Galvani's assertion that animal electricity existed in a form entirely independent of any external electricity, though it had been accepted by most of the distinguished men of science of the time, seemed to Volta without experimental verification. For many years his most determined efforts were used to demonstrate that the muscle twitchings observed were not due to the presence of animal electricity (galvanism as it had come to be called), but to the fact that the metals touching the different portions of the moist nerve muscle preparation really set up minute currents of ordinary electricity.