1. ON forming a Circle by means of the parts of a living Animal and of two different metallic Bodies, especially Gold and Zinc, in contact with each other, if a Nerve makes part of the Circle, the Muscles in which the Nerve terminates are convulsed. 2. ALTHOUGH the Nerve making part of such a Circle has been cut transversely, yet, if the divided parts of the Nerve are laid in contact with each other, or tied together, the Muscles, in which it naturally terminates, are convulsed. 3. IF the Metals, composing parts of the Circle, are kept steadily in contact with each other, the convulsions of the Muscles cease. But, if they are separated from each other and again rejoined, the convulsions are repeated. 4. THE effects are the same, although the dead parts of an Animal or pure water make parts of the Circle. 5. ALTHOUGH the dead parts of an Animal, making part of such a Circle, are in contact with the Metals, the effects are the same. 6. A MUSCLE making part of such a Circle may be convulsed whilst the matter put in motion is passing in the direction from the Muscle to the Nerve. 7. THE Muscle may be convulsed although it makes no part of the Circle in which the matter put in motion passes, as appears from comparing Experiment 5th with Experiments 13th and 14th. From Experiment 13th, it appears, that the Fluid put in Motion by the Metals passes readily along a Nerve, after it has been cut, providing the divided Parts of it are brought into contact with each other. Yet in Experiment 14th, in which the left hand of the Operator was not applied to the Foot of the Frog, the Muscles in which the Nerve, lower than the Ligature, terminated, were not convulsed, because the Fluid put in motion did not descend lower than the place at which the gold Probe touched the Nerve above the Ligature. We may therefore presume that when a Nerve which has not been cut, as in Experiment 5th, is touched with the gold Probe, the Fluid put in motion does not pass lower in the Nerve than the place of the Probe. Hence we perceive the error of those who suppose that the moisture on the surface of the Nerve conduces the Fluid put in motion to the Muscles, and that their action is in consequence of the direct operation of this Fluid upon their Fibres. 8. THE effects are the same when the Animal and the Metals are insulated, by being placed on Glass, whilst Sealing-wax is interposed between the hand of the Operator and the Metals. 9. IF any part of the Circle is composed of Sealing-wax or Glass, the Muscles are not convulsed. 10. CONVULSIONS are not excited unless the Metals are in contact with each other; and unless both Metals are also in contact with the Animal Substances or the Water making part of the Circle. RESEMBLANCE OF THE FLUID PUT IN MOTION BY THE FOREGOING EXPERIMENTS TO THE ELECTRICAL FLUID.