contrivance, all that is necessary is to let the piece of nerve touch simultaneously in two places the part where electric condition is to be examined. If a current exists, the muscles of the leg will become convulsed at the moment of contact. In this way the Professor detected a current in man, by making a clean incision into the muscles of a recently amputated limb, and bringing the nerve of the frog galvanoscope in contact at once with the two lips of the wound, contraction instantly occurred. In a recent paper, Matteucci has fully corroborated the statement long before made by Mr. Wilkinson of the marvellous sensibility of the irritable muscles of the frog to the stimulus of electricity. For even after an electric jar has been discharged, and the two surfaces of the jar repeatedly brought into communication, so as to get rid of any residual charge, and lose all influence on the more delicate electrometer, its electric equilibrium is still sufficiently disturbed to readily excite convulsions in the frog-galvanoscope. In pigeons and fowls, as well as in eels and frogs, currents were readily demonstrable; indeed, by alternating a series of the former by approximating their sides, the raw surface of the muscles of which had been exposed by a quickly made cut, Matteucci formed a sort of battery resembling that made of the thighs of frogs. The result of this experiment has proved that energetic currents existed in hot as well as cold-blooded animals: indeed, more intensely, but very soon disappearing on the death of the animal. These researches completely corroborate the statements and experiments of Aldini made many years earlier, especially that very remarkable one before alluded to, in which he produced contractions of the legs of a frog by bringing them in contact with the tongue of an ox. By means of the frog galvanoscope, not only the existence, but the direction, of a current can be discovered; for if the leg be kept for a short time before using it, so as to a little diminish its sensibility, the muscles will contract on making contact with the body under examination, if the positive electricity passes from the nerve to the leg, whilst it will contract on breaking contact if the electricity is moving in the opposite direction. Using this delicate test for an electric current, Matteucci discovered that the intensity of such currents rises in proportion to the rank occupied by the animal in the scale of being, their duration after death being in the inverse ratio. The Professor discovered, that when a mass of muscle belonging to a living animal, or one recently dead, was placed in contact with a piece of wire so that one end of it touched the tendon, and the other the body of the muscle, a current could always be detected circulating in the mass in the direction from the tendon to the external surface of the structure. He further demonstrated the very important fact, that every thing which decreases the vis vitæ of the animal diminishes the evidence of electricity immediately after death. Thus, when frogs were killed by asphyxia, either by immersion in sulphuretted hydrogen, or water freed from air, the electricity detected in their femoral muscles sunk to a minimum; whilst the thighs of frogs whose hearts had been previously removed gave less evidence of the existence of this important agent than those which had not been thus injured. It is well known that certain fishes possess a peculiar apparatus by which they are enabled to accumulate the electricity developed by the vital processes going on in their structures, and thus produce the ordinarily recognised effects of tension, as shown in the benumbing shock felt on grasping a torpedo or gymnotus. This endowment is, however, peculiar to very few creatures, and all the electricity developed in the frames of other organisms is only to be detected by comparatively delicate tests. It is, however, very remarkable, that in the batrachians generally, especially the frog, an electric current, denominated by Matteucci the "proper current," possessing some approach to tension, and capable of deviating the needle of a galvanometer to 5°, can readily be detected; its direction is always definite from the feet towards the head. This curious and remarkable fact was, I believe, first pointed out by Nobili, but accurately studied by the Pisan philosopher to whose researches I have so often referred. 3333 LECTURE II. Origin of Animal Electricity dynamic State.- Traced to chemical Action Electrogenic Effects of Respiration and Metamorphosis of Tissue.— Of Decomposition of Salts in the Body.-Electrolytic Effects of such low Currents.-Formation of Ammonium.- Electrogenic Effects of chemical Union · Applied to the muco-cutaneous and muscular Currents. — Arrangement of acid and alkaline Fluids in muscular Structure.. Electrogenic Effects of Evaporation — Of heterogeneity of Structure .Function of Electricity · As a Cause of Secretion. — Napoleon's Hypothesis.— Failure of Attempts to detect Currents in the Nerves. — Electricity as a Cause of muscular Contraction Prevost's and Dumas's Views - As the digestive Agent How far admissible. Dependence of gastro-hepatic Current on nervous Agency.—Mr. Baxter's Researches.— Theories of Orioli, Meissner, and Herschel.-Zamboni's Piles. - Reputed Influence of Electricity on the capillary Circulation. In a State of Equilibrium - In a - IN my last Lecture I pointed out the universal distribution of electricity in brute matter, and exhibited some of its effects when its equilibrium is disturbed by mechanical, chemical, and thermal influences, and then proceeded to demonstrate its existence in living beings, and succeeded in obtaining it in a state of tension from my own body. The great discovery of Galvani, and the more recent researches of Nobili, Matteucci, and others, next engaged our attention; and, having adduced D |