plate, I will place a piece of zinc in contact with the nerves, and allow the feet to rest on a thin slip of silver. They are now at rest, and appear, as they indeed are, dead and powerless. But there exists a power I can call into action which will endow these dead limbs with an apparent life. The only spell required to evoke this power is this piece of wire, with one end of which I will touch the zinc, and with the other the silver. Instantly the legs violently contract, and kick away the silver plate.

It has been lately stated by Professor Matteucci, that this curious observation was not original with Galvani, but was made some time before by the celebrated Swammerdam; and the experiment was exhibited by him in the presence of the Grand Duke of Tuscany.

Shortly after the announcement of this discovery, Professor Volta, of Pavia, in repeating this and other analogous experiments, arrived at a different conclusion; and he showed that the electricity was really excited by the metals, and the contraction of the muscles of the frog was only an index of its existence. Although these and other discoveries of that great man obscured for a time the views and researches of the illustrious Galvani, attention was again drawn to them by the experiments of his talented nephew, Professor Aldini, of Bologna. He was inspired

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with so much zeal in the defence of his uncle's theory, that he travelled through France and England for the purpose of demonstrating the truth of his views; and in the presence of the medical officers and pupils of Guy's Hospital, he, in the year 1803, supported and defended a series of propositions so satisfactory and conclusive, that he was presented by his auditors with a gold medal commemorative of his labours. On leaving England, these propositions, and the arguments in support of them, were published in a quarto volume, which seems to have attracted but little notice either here or on the continent of Europe. Scarcely any mention is made of Aldini by more modern writers; and not many weeks ago I removed the volume from the library of the Royal Medical and Chirurgical Society with its leaves uncut.

Professor Aldini's propositions and conclusions are so important, and of such high interest, that I shall now briefly refer to some of them, as they demonstrate to my mind, in a most satisfactory manner, the existence of free electricity in animals, and, as will appear to all conversant with this branch of physiology, most remarkably anticipate the late researches of his countryman, Prof. Matteucci.

PROP. 1.-" Muscular contractions are excited by the development of a fluid in the animal machine, which is conducted from the nerves to the

muscles without the concurrence or action of metals."

Exp. A. In proof of this statement, Aldini procured the head of a recently-killed ox. With the one hand he held the denuded legs of a frog, so that the portion of the spine still connected with its lumbar nerves touched the tip of the tongue, which had been previously drawn out of the mouth of the ox (fig. 6.). The circuit was completed

Fig. 6.

by grasping with the other hand, well moistened with salt and water, one of the ears. The frog's legs instantly contracted; the contractions ceasing the instant the circuit was broken by removing the hand from the ear.

The intensity of these contractions was much increased by combining two or three heads so as to form a sort of battery, just as Matteucci, forty

years afterwards, found to be the case with his pigeon and rabbit battery.

Exp. B.-Aldini, having soaked one of his hands in salt and water, held a frog's leg by its toe, and, allowing the ischiatic nerves to be pendulous, he brought them in contact with the tip of his tongue. Contractions instantly ensued from a current of electricity traversing the frog's leg in its route from the external or cutaneous to the internal or mucous covering of the body. By this very interesting experiment Aldini demonstrated the existence of the musculo-cutaneous current, and completely anticipated its re-discovery by Donnè some five and thirty years after.

Aldini, in connection with this experiment, declares that the pendulous nervous filaments were distinctly attracted by the tongue; and to this marvellous and hitherto uncorroborated statement calls to witness the then physicians and professors of Guy's and St. Thomas's Hospitals, as well as two well-known fellows of this College; Sir Christopher Pegge and Dr. Bancroft, to whom he states he showed this experiment at Oxford.

Exp. C.-The proper electricity of the frog was found by Aldini to be competent to the production of contractions. For this purpose he prepared the lower extremities of a vigorous frog,

and, by bending up the leg, brought the muscles of the thigh in contact with the lumbar nerves Fig. 7.

(fig. 7.): contractions immediately ensued. This experiment is now a familiar one, and has been repeated and modified lately by Müller and others.

Exp. D.-A ligature was loosely placed round the middle of the crural nerves, and one of the nerves applied to a corresponding muscle: contractions ensued; but, on tightening the ligature, convulsions ceased.

This statement is very important, as upon its accuracy or error depends what has been regarded as one of the tests of the identity or diversity of the electric and nervous agencies. It was repeated soon after Aldini's announcement of the fact by an Italian physician of celebrity, Signor Valli, who commenced his researches indeed in 1792, only a year after the publication of Galvani's discovery, and he found if the ligature were applied near the muscle it did not allow the contraction to occur, but if nearer the spine it did not prevent it. This was afterwards corroborated by Humboldt. I may here remark that it has been