Commentary on the Effect of Electricity on Muscular Motion

...counsel, so that we may pave some way for undertaking new experiments, by which, if we cannot reach the truth itself, at least a new entrance to it may be opened.

This is how the matter began. I dissected a frog and prepared it as shown in Figure $Ω$, Plate 1. I placed it on a table where there was an electrical machine original: "machina electrica". This refers to a friction-based electrostatic generator common in 18th-century labs. (Figure 1, Plate 1), though I was intending to do something else entirely. The frog was placed completely separated from the machine's conductor and situated at quite a distance from it. While one of my assistants original: "unus ex iis, qui mihi operam dabant". Galvani often worked with his wife, Lucia Galeazzi Galvani, and his nephews. happened to lightly touch the internal crural nerves The nerves of the thigh and leg. D D of this frog with the tip of a scalpel, suddenly all the muscles of the limbs were seen to contract so violently that they appeared to have fallen into intense tonic convulsions. original: "tonicas convulsiones"; these are prolonged, involuntary muscular contractions.

Truly, another person who was present while we were testing the electricity seemed to notice that this phenomenon occurred only while a spark was being drawn from the conductor of the machine (Figure 1, B). Marveling at the novelty of the thing, he immediately brought it to my attention while I was busy with other matters and deep in my own thoughts. At this, I was inflamed with an incredible zeal and desire to test the same thing myself and to bring to light what was hidden in this occurrence. Therefore, I myself applied the tip of the scalpel to one or the other crural nerve at the same time that someone present drew out a spark. The phenomenon occurred in exactly the same way; certainly, violent contractions were induced in every muscle of the limbs, just as if the prepared animal were seized by tetanus, at the very same moment that the sparks were drawn out.

But fearing that these movements might arise from the contact of the scalpel's tip—which might act as a stimulus—rather than from the spark, I tested the same nerves again in the same way in other frogs using the tip (and indeed more forcefully) without any spark being drawn at that time; however, no movements at all were seen. Hence, I thought to myself that perhaps to induce the phenomenon, both the contact of some body and the discharge of a spark were required together. Therefore, I again applied the edge of the scalpel to the nerves and held it motionless, both at the time when a spark was extracted and at the time when the machine was perfectly at rest. But the phenomenon appeared only when a spark was drawn out.

We repeated the experiment always using the same scalpel; however, to our surprise, sometimes the recorded movements occurred when a spark was drawn, and sometimes they failed to happen.