In the experiments that had been performed on animals, those with cold blood had been generally employed, both on account of their being more convenient for the operation, and from the greater tcnaoity with which they retain their vitality. It was, however, ascertained, that animals with warm blood Nvere equally susceptible of the influence ; and Crewe of Wort zburg had produced strong contractions in a human leg after amputation. Vassali, in conjunction ith Its Friends, Giulio and Rossi, performed a more am ple set of experiments upon the brIfies of some criminals that were beheaded at Turin. (.11w-it. de Phys. Iv. 286.) They paid particular attention to the effect of the galvanic electricity upon the heart and the other involuntary mus cles, a point which had been the subject of much contro versy. Volta supposed that the involuntary muscles could not be made to contract. Fowler however asserts, that con tractions were excited in the heart, although with difficulty ; and Vassali confirmed the observations of Fowler, and ex tended them to the stomach and intestines ; the same opi nion was also maintained by Nysten. (bourn. Phys. lv. 465). On the other hand, Aldini, the nephew of Galvani, who now came into notice as an assiduous experimentalist, asserted that he was unable to act upon the heart.
Circaud announced a discovery, which, if it were fully confirmed, would prove of great importance in physio logy, that the fibrinc of the blood, immediately after it leaves the vessels, may be made to contract by the galva nic apparatus. Delametherie confirms the statement of Circaud, from his own observations ; but we have been in formed that the experiment has not succeeded in this coun ; when we consider the difficulty and delicacy of the process, we may be allowed, without impeaching the vera city of the narrators, to entertain some doubts on the sub ject. See Journ. Phys. Iv. 468 ; and lv. 161.
In the year 1803, Aldini his Treatise on Gal .vanism, a" work which contains many curious experiments, and also some new theoretical opinions. The experiments which were the most calculated to produce an impression upon the spectators, were performed on the body of a crimi nal, who was hanged at Newgate, and also on the head and limbs of some of the larger warm-blooded animals. A pow erful battery being applied, Very strong contractions were excited, the limbs were violently agitated, the eyes opened and shut, the mouth and jaws worked about, and the whole face was thrown into frightful convulsions. These experi ments, however, were principally remarkable from the sub jects made use of, and the magnitude of the effect : there were others performed, really more curious, in which very considerable muscular contractions were excited, without the intervention of any metal, or other substance which could be supposed capable of disengaging the electric fluid. In some cases the effect was produced by bringing into con tact the nerve of one animal with the muscle of another, and at other times by employing the nerves and muscles of the same animal. In some of the experiments, there ap
pears to have been the most powerful contractions excited, by bringing the parts of a warm and a cold blooded animal into contact with each other. It does not appear, from any expressions in this treatise, whether Aldini considered the animal electricity, as he calls it, to be of a specifically dif ferent kind from that excited by the pile, or whether he supposes that the different parts of the animal body have the power of generating the same kind of electricity, with out the aid of any external agent. He, however, deduces from his experiments an inference in favour of Galvani's hypothesis, of a proper animal electricity inherent in the body, and not requiring assistance of any external agent for its developement.
There are some points respecting these experiments that require farther explanation. The most obvious con clusion that we should draw from them, would be that which was formed by Aldini himself, in favour of a proper animal electricity. But if this be the case, they must be regarded as essentially different from those of Galvani, where an electricity of the usual kind was certainly excit ed. Perhaps the most probable supposition is, that the parts of the body, in these experiments, acted in a manner analogous to the pile which was constructed by Sir II. Da vy, in which electricity was developed by the action of two different fluids upon carbon. There arc, however, many circumstances wanting, to render this analogy complete.
An important experiment was announced by Lagrave : he stated, that by placing upon each other alternate layers of muscular fibre and of brain, separated by a porous body, soaked in salt water, a pile was formed, which produced the usual effects of the Galvanic apparatus : (Journ. Phys. lvi. 235.) The experiment must be of difficult execution, and we do not know that any one has since attempted to repeat it. Should it be confirmed, it would throw some light upon the experiments of Aldini, and would assist in the explanation of those facts, where animal electricity seemed to be developed, without the intervention of metal lic bodies.
About this time galvanic electricity began to be extensive ly employed in medicine, especially in those diseases where common electricity had been previously found useful. It might have been expected that much benefit would have been derived from so powerful an agent, and one which is so easy of application to any part of the body. Our expectations of advantage have, however, been generally disappointed. Flattering accounts of success were indeed published, in different nervous disorders, in paralytic affections, in deaf ness, in some kinds of blindness, in the recovery of persons apparently drowned or suffocated, and even in hydropho bia and insanity. But we believe that the practice is now very generally relinquished, from a conviction of its in utility.