The NERVOUS FLUID or ENERGY not the same with the ELECTRICAL nor with the FLUID put in motion by the foregoing EXPERIMENTS.
That the Nervous Fluid is the same with the Electrical, or with the Fluid which is put in motion by the foregoing Experiments, is, I apprehend, disproved by the following circumstances.
1. Without stating the difficulty there is in conceiving how the Electrical Fluid can be accumulated by or confined within our Nervous System, we may observe that where the Electrical Fluid, or Fluid resembling that put in motion by the foregoing Experiments, is accumulated by an Animal, such as the Torpedo or Gymnotus, a proper apparatus is given to the Animal, by means of which it is enabled to collect and to discharge this Fluid.
2. The Nervous Power is excited by chemical or by mechanical Stimuli; and, on the other hand, is destroyed by Opium and other Poisons, which cannot be imagined to act on the Electrical Fluid.
3. I have, I apprehend, refuted the theory of Doctors Galvani, Valli and others, which supposes that the Nerve is electrified plus and the Muscle minus, resembling the Leyden Phial, by shewing that the Muscles are convulsed where there is no communication between them and the Metals, but by the medium of the Nerve; or when the Metals are applied to different parts of the Nerve alone, without touching the Muscles which are convulsed, and when the Muscle which is convulsed makes no part of the Circle in which the Matter that is put in motion passes.
4. I have proved, that the Muscles are convulsed whilst the current of the Electrical Matter is passing from them and from the smaller Branches of the Nerves into their Trunks; and as a Muscle is never thrown into Action by the Nervous Energy, except when this passes from the Trunk of the Nerve into its Branches, and from these into the Muscle, it appears that when, in these Experiments, the Muscles were convulsed, the Nervous and the Electrical Fluids were moving in opposite Directions; from which we may infer, that, in their Nature, they differ essentially from each other.
5. The Nervous Energy is stopped by a tight Ligature or by the transverse Incision of a Nerve, although its divided Parts are thereafter placed in contact with each other; whereas the Electrical Fluid or the Fluid excited by the Metals, passes readily, downwards or upwards, along a Nerve which has been tied or cut.
6. After the Limb of a living Animal has been amputated, frequent Convulsions of the same Muscles may be excited by applying Mechanical or Chemical Stimuli to its Nerves; whereas Electrical Matter discharges itself suddenly.
Hence I conclude,
1. That the Fluid, which, on the application of Metalline Bodies to Animals, occasions Convulsions of their Muscles, is electrical, or resembles greatly the Electrical Fluid.
2. That this Fluid does not operate directly on the Muscular Fibres, but merely by the Medium of their Nerves.
3. That this Fluid and the Nervous Fluid or Energy are not the same, but differ essentially in their Nature.
4. That this Fluid acts merely as a Stimulus to the Nervous Fluid or Energy.
5. That these Experiments have merely shown a new mode of exciting the Nervous Fluid or Energy, without throwing any farther or direct Light on the nature of this Fluid or Energy.
FINIS.