292 THE POPULAR SCIENCE MONTHLY 



ciations and dissociations of atoms and molecules — of anions and 

 cations— in the complex phenomena of metabolism throughout the body. 

 jSTo nutritive change, even in a single cell, can take place without a dis- 

 turbance 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 electro- 

 magnetic 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 Con- 

 gress of Electrology and Eadiology held in the University of Amster- 

 dam,* when Professor Salomonson, by using Einthoven's string-galvan- 

 ometer (a sort of electric microscope), was able to measure, and render 

 visible on a photographic plate, the electric current producing one con- 

 traction 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 cur- 

 rents 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 evi- 

 dent that in order to secure and use the power thus produced the appa- 

 ratus 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. 



4 Proceedings of the Royal Society of Medicine, November, 1908. 



