Page:Popular Science Monthly Volume 75.djvu/296

292 ciations and dissociations of atoms and molecules—of anions and cations—in the complex phenomena of metabolism throughout the body. No nutritive change, even in a single cell, can take place without a disturbance of electric equilibrium and the development of an electric current, be it ever so diminutive. Nerve force, electricity and "vital force" are identical in so far as they are all manifestations of electromagnetic energy. Every histological unit in an animal body is a diminutive battery in which such energy is evolved. This, I think, is common knowledge, that has passed beyond the realm of theory.

Perhaps the crudest and most evident illustration of the production of electricity by animal metabolism is exhibited in the electric fishes: the torpedo, the Gymnotus (electric eel), the Malapterurus (electric catfish), the skate and others. In these forms, it is true, we find a special electric apparatus, consisting of some hundreds of columns made up of millions of superimposed plates or discs, arranged transversely to the length of the columns and separated from one another by an albuminous liquid, thus resembling a voltaic pile. The distribution, or discharge of this electric energy is controlled by nerves emanating from the medulla oblongata. Thus the animal, at will, can shock and capture its prey, and even emit charges, in some instances, sufficient to injure, and perhaps kill, even men and horses.

A more delicate method of demonstrating the identity of nerve force and electricity was shown at the last meeting of the International Congress of Electrology and Radiology held in the University of Amsterdam, when Professor Salomonson, by using Einthoven's string-galvanometer (a sort of electric microscope), was able to measure, and render visible on a photographic plate, the electric current producing one contraction of a single muscle, for example, that of the quadriceps femoris during the patellary reflex. Even currents producing contractions in the cardiac muscles were exhibited. He presented on the screen a cardiogram, by which, he remarks: "Each muscular fiber of the heart has written its own sign-manual on the photographic plate." By means of this device he was able to exhibit visibly events successively occurring at intervals of one one-hundredth of a second, and electric nerve currents so small as the one ten-thousandth part of a single volt.

Now if every living animal, and every cell within it, be really an electrical machine—a generator of electro-magnetic energy—it is evident that in order to secure and use the power thus produced the apparatus must be insulated from its surroundings, otherwise the electricity would instantly escape back into the earth whence it came. All our electric machines and batteries are thus insulated.

Are animal bodies provided with this electric insulation? They are.