CHAPTER VII. THE EVOLUTION OF ELECTRICITY IN THE ANIMAL ORGANISM-WHAT ARE FACTS ON THIS POINT? Development of electricity in the animal organism - Matteucci's experiments on muscular contraction - Dr. W. F. Channing's idea Electric emanation during muscular contraction discovered by M. Boys Raymond - Humboldt's testimony - Muller's discovery Smee's experiments-Those of Prevorst and Dumas-Ahran's and Paph's - M. Hemmer's-Sir James Murray's discovery of the electric powers of the spleen Matteucci's experiments on electric currents in the muscles- Nervous current not electric-Influence of the will over the electric discharge- Electric fish-Its electric organ - Power of discharging a current of force from the organism - The decision as to the discharge and direction depending on an action of the brain-The electric power related to the will-The odylic related to the automatic action of the brain - Important difference. 226. It is well known to every chemist, that wherever there is chemical action there is an evolution of electricity. Now the vital force is constantly keeping up a chemical action in the animal organism; it must follow, therefore, that there is a constant evolution of electric agency in that organism. "It would be absurd to suppose," says Matteucci," that the chemical actions of living beings, all of which develop heat, and often light, would not be accompanied by the production of electricity." The experiments of Matteucci, upon the muscles of animals, show that they act as clements of a voltaic pile. Thus, "when we connect the interior and the surface of the muscle of a living See Lectures on the Physical Phenomena of Living Beings. By Carlo Matteucci, Professor in the University of Pisa. Philadelphia, Lea and Blanchard, 1841. p. 177. or recently killed animal, by means of a conducting arc, the existence of an electric current is then vigorously demonstrated. This current is always directed from the interior to the exterior of the same muscles. It exists without the direct influence of the nervous system, and is not modified even when we destroy the integrity of the latter."* Further on the same philosopher states "that the existence of an electric current in the muscles has been well demonstrated, and that its principal laws are established. The origin of this current," he continues, "resides in the electric conditions which are produced by the chemical action of the nutrition of the muscles. The blood charged with oxygen, and the muscular fibre, which becomes transformed on contact with this liquid, compose the elements of a pile; they are the liquid acid and zinc.”† 227. It is not, however, from the nutrition of the muscular system alone that the evolution of electricity takes place; nor is it to chemical action alone that it can be attributed. It is found also to be evolved in the molecular changes which take place in substances. In fact, it is well known to all philosophers that every change of matter, however slight, occasions an electric development. The conversion of fluid into vapor; the condensation of gases into liquids ; the mixture of fluids; the solution of solids in fluids; the local action of heat; the disintegration of substances, or the breaking up of larger bodies into particles; alterations in the relative position of particles; the friction of one body upon another, all are sources of electric development and action. Now, in this catalogue of material changes, there is scarcely one that is not, more or less, constantly taking place in the animal organism. There is not a muscular movement, voluntary or involuntary, that does not break up portions of the organism into particles; neither is there. a motion of the brain, indeed, by thought, passion or emotion, that does not produce the same effect. This change of matter in the organism, this constant disintegration, *Lectures on the Physical Phenomena of Living Beings, page 185. + Ibid., page 188. must, therefore, constantly evolve the electric agency. Respiration, circulation, digestion, secretion, excretion, are constantly giving freedom to this force. 228. We may well say, then, in the language of Dr. W. F. Channing, "Not only the exertion of muscular power, but every exertion of vital power, follows the law of elimination of material forces, the development of which, from latent conditions, is inseparably attended by a change of form in the associated matter."* 229. It should follow from this, that, by fulfilling the proper conditions, the evolution of electricity during muscular contraction may be detached. Accordingly, M. Emile du Boys Reymond, and after him Humboldt and other philosophers, have, by a very delicate instruinent, detected the electric current excited during the contraction of the muscles of the arm.† The current is found to direct itself from the hand to the shoulder. M. Reymond observed the deflection of the needle to amount to 30°, and even beyond this, by alternately contracting the muscles, first of one arm and then of the other, in time with the oscillations of the needle. "On bracing simultaneously the muscles of both arms, very small deviations were observable, sometimes in one direction and sometimes in another. These minute deflexions were evidently caused by the difference between the contractile force of the two limbs. Hence it arises, that when the experiment is repeated See Notes on the Medical Application of Electricity, by W. F. Channing, M. D. Boston, 1849. The manner of effecting this is thus given by M. Reymond in a letter to Humboldt, which the latter sent to the Paris Academy of Sciences, in May, 1849. Two slips of perfectly homogeneous platina are fixed at the extremities of a very sensitive galvanometer. These slips are immersed in two vessels filled with salt and water, into which also the experimenter introduces two corresponding fingers of his two hands. When this is done the needle must stand at zero, while no exertion is made with the muscles of either hand or arm. If he now strain all the muscles of one arm, so as to establish an equilibrium between the flexors and extensors of all the joints of the arm, there will be at once a movement of the needle. See Comptés Rendus, May 28, 1849. Also Annual of Scientific Discovery for 1850, p. 114. many times successively, the results diminish gradually in amount.' 230. "The amount of deviation depends upon the degree of development and exercise of the muscles. The habitual superiority of the right hand over the left, in this experiment, is to be interpreted by the preponderance of the amount of deflection produced by the tension of the right 231. M. de Humboldt says: "The fact of the experiment affecting a magnetic needle by the alternate tension of the muscles of the two arms, an effect due to volition,is established beyond the shadow of a doubt. Notwithstanding my advanced years and the little strength that I have in my arms, the deflections of the needle were very considerable." 232. Since the announcement of these experiments many persons have tried similar ones, and only in a single case, that of M. Becquerel, has there been any failure noticed." 233. Thus we have the highest scientific authority for the fact, that there is not only an evolution of electricity in the muscular system, but that it is appreciable by the galvanometer during the contraction of the muscles. It is due, however, to one of our own countrymen, Dr. Wm. H. Muller, of Pittsburgh, to say, that this latter fact was discovered by him as early as the year 1842. The following is his own language in a communication to the Magnet : § "What I have ascertained is this, namely, that a comparatively large amount of electricity can be developed in all persons, I may say, of both sexes and all ages, by muscular contraction, in a certain position, and only in such a position, together with a proper dryness of the surrounding air. If these conditions are not observed no electric manifestations occur." As his experiments are novel and important, we will state some of them in this place. Dr. Muller had attempted in several instances to verify the results of M. Hemmer's experiments with regard to the electric * See Annual of Scientific Discovery for 1850, p. 115. force of the human organism. Having failed, however, he at length hit upon a new experiment. To see what effect a benumbed limb would have upon a gold-leaf galvanometer (the limb having gone to sleep while it lay across the back of a chair), he arose hastily and applied his fingers to the cover of the instrument. "The gold-leaf flew instantly to the sides of the glass." This at first he supposed to be owing to the peculiar condition of the hand. He soon discovered his mistake; for, "on rising again, and applying the other hand, which was in its natural state, the same phenomenon occurred." On varying his experiments, he soon found that the phenomenon depended on his rising from a sitting posture. He then tried this upon other persons, with some of whom it succeeded on the first trial; while, with others, it was at first a failure, but ultimately successful. He experimented upon thirty persons, of both sexes, different ages, and in different rooms, with " complete success.' A little girl of seven years," he remarks, "has shown very strong electric powers. To cause a movement of the gold-leaf of half an inch from the perpendicular is but a weak manifestation." In some of his experiments he found the electric emanation during muscular contraction "sufficient to tear the leaf, causing it also to adhere to the side of the glass." "It is not necessary for me," he says, "even to touch the cover of the instrument; nearly as striking results will follow if I bring my hand near the cover, say within an inch or more." This electric phenomena did not arise from friction; his precautions against this rendered it impossible. 234. The following are the conditions which he observed to be necessary in order to effect the results: First, A proper dryness of the atmosphere. This condition is very important, as well as, Second, A dryness of the surface of the body.* "It was for want of attention," he observes, "to having the air dry, and to my overlooking a cause of moisture, that I was, at first, in doubt whether the electricity did in fact arise from the body without the aid of clothing." Hence, perspiration dissipates the electricity, and is to be avoided in the experiments. |