ELEMENTARY VITAL PHENOMENA 263 



thermal animals show the latter. The former may be observed 

 without further aid only where it occurs in large proportions, i.e., 

 only in the electric fishes, whose powerful shocks were known 

 even to the ancients. The history of the science of animal 

 electricity is associated closely with the discovery of galvanism 

 and with the names of Galvani and Volta. It is certainly a note- 

 worthy fact that the discovery of the physical fact of galvanism 

 required for its starting-point physiological phenomena. 



In September, 1786, Aloisio Galvani was making investi- 

 gations upon the terrace of his house in the ancient university 

 city of Bologna on the influence of atmospheric electricity 

 upon a frog's leg from which the skin had been removed. 

 Several years before he had carried on similar researches with 

 the aid of his wife, Lucia, since early deceased. In the course 

 of his experiments he stuck a copper hook through the frog's spinal 

 column, which was still in connection with the nerves. When he 

 laid this preparation upon the iron railing of the terrace he 

 noticed to his astonishment that whenever the hook touched the 

 railing, the frog's leg attached to it executed violent contractions. 

 This simple observation is said to have been the starting-point of 

 the discovery of contact electricity, the inconceivable range of 

 which in relation to civilisation is only now appreciated. 

 Alessandro Volta discovered the explanation of this phenomenon 

 by establishing the fact that in the contact of two different metals 

 with a moist conductor an electric tension arises, which is equalised 

 in the form of an electric current as soon as the metals are joined 

 with one another. In Galvani's experiment the nerves and 

 muscles of the frog constituted such a moist conductor between 

 the copper hook and the iron railing ; the current went through 

 the muscles and stimulated them so that they contracted. This 

 correct interpretation of Volta was opposed by Galvani, who 

 imagined that the twitch of the frog's leg might be caused by 

 electricity originating within the leg itself; but this error is 

 said to have led him fortunately to a new discovery. In labouring 

 to prove to Volta that the contact of metals was not necessary for 

 the production of the twitch, he endeavoured to bring out the 

 twitch without metals ; and he succeeded in this by placing the free 

 end of a freshly prepared nerve of a frog's leg in contact with the 

 flesh. In this experiment, as is now known, the nerve is stimulated 

 by the electric current produced in the muscle itself; and so 

 Galvani became the discoverer of animal electricity, as previously, 

 although unwittingly, he had discovered contact electricity. 



Pfaff, Humboldt, Ritter, Nobili, Matteucci and others laboured 

 in the further development of the science of animal electricity, 

 but it was reserved for the classic investigations of du Bois- 

 Reymond ('48 — '84) to place this field of physiology, which was then 

 half-mystical and constituted one of the chief supports of the doctrine 



