After a considerable time had been employed in the preceding experiment, I endeavoured to revive the action of the Galvanism by moistening the muscles with a solution of opium. By these means the contractions seemed to be increased; and the case was the same in other warm-blooded animals. A series of similar experiments, if carefully made, would no doubt be attended with important results; as they might enable us to ascertain the action of the different stimulants proposed by Dr. Brown. But I must, in the mean time, observe, that the before-mentioned effects of opium fully correspond with those long ago observed by Galvani.
It results, in general, from my experiments, that moisture performs a conspicuous part in producing contractions; and that it is even of more importance than animal heat. I indeed find that muscular contractions may be obtained after the body has thrown out a great deal of its heat, even when it has cooled for several hours, and when it has been exposed to a temperature below zero; for, if Galvanism be communicated to a body in that state, muscular contractions will be immediately excited; but they soon cease by the privation of animal moisture. If a muscle, indeed, which has been laid bare resists the Galvanic influence, its action may be speedily renewed by making an incision into it, or into some of the muscles which surround it. I can assert, that by this process partial contractions were produced in the human body five hours after death, every time that the arcs were applied to the muscular fibres.
Being worn out with this long series of experiments, I found it necessary to abandon them; but, from the force of the contractions, it could easily be seen that they might have been produced much longer.
Having communicated these results to the celebrated Caldani, Professor of Anatomy in the University of Padua, he requested that I would confirm the observations I had made by again applying Galvanism to the membranes and to the cortical substance of the brain. He was unwilling to give up the system of Haller without very positive proofs; and his doubts were to me of great utility, as they induced me to
establish the action of Galvanism on these parts by the following experiments:
EXPERIMENT LV.
As these doubts related to a delicate point, which would have produced some variation in the theory of a celebrated physiologist, I repeated the experiment on the head of an ox newly killed, in the presence of Professor Mondini, who made the necessary preparations. The dura mater was laid bare; and the action of the Galvanism being conducted to it, strong contractions were immediately produced. The same phænomenon took place when the cortical substance was brought into contact with one of the arcs. I repeated this experiment with the same success on the heads of several oxen and lambs.
EXPERIMENT LVI.
When I passed through Turin, Professors Vassalli, Giulio, and Rossi requested me to perform, in their presence, my principal experiments, and those in particular which related to the membranes and the cortical substance of the brain. They observed, at the same time, that in uncovering the brain of an ox with a cleaver, some derangement, in consequence of the agitation, might be effected in that organ, which would perhaps produce an alteration in the results. Professors Giulio and Rossi proposed therefore to uncover the brain by the trepan, which gave a greater degree of precision to
the experiment. The dura mater of an ox being uncovered in this manner, it was subjected to the action of Galvanism, and even with this mode of preparation the muscular contractions every time the arc was applied were pretty strong. The arc being determined to the cortical substance, the force of the contractions seemed to be increased; and in general they appeared to be more considerable in proportion as the arc was plunged to a greater depth into the substance of the brain.