OF VITAL PHENOMENA 119 



served that if one frog's skin is laid on another, the emf is 

 doubled. In the same way he found the emf of two concentra- 

 tion cells with porcelain membranes to be doubled when they 

 were connected in series. The principle is the same as that of 

 the voltaic pile, and only the nature of the membrane is different. 

 A dissection of an electric organ reveals the serial arrangement, 

 and also (in all ekctric organs related to muscle tissue) that 

 the side of each element on which the nerve enters is electro- 

 negative (Pacini). It seems probable that the manner of pro- 

 duction of electricity is the same in the electric organ as in muscle 

 or nerve or any sensitive cell. We shall therefore proceed to 

 discuss the general question of the exhibition of electromotive 

 force by the cell. 



The electromotive force of a single cell was observed by Hyde 

 (1904). She placed one non-polarizable electrode on the animal 

 pole and one on the vegetative pole of the egg cell of a fish. 

 When the cell began to divide the animal pole became negative. 



Owing to the small size of most cells, it is usually more con- 

 venient to study these phenomena in tissues in which similar 

 cells are arranged in multiple. The frog's muscle is convenient. 

 It is possible to measure the difference in potential between the 

 inside and outside of the cells by cutting off one end of the 

 muscle and leading off from the cut surface (interior) and the 

 intact surface (exterior). The interior is found to be negative 

 in comparison to the exterior, which causes an electric current 

 to flow through any external conductor that may be present from 

 the intact to the cut surface. This current is often called the 

 current of injury, without any proof that the injury, as such, 

 has anything to do with it, but the expression is convenient. 



Wilhelm Ostwald suggested that the muscle is a concentration 

 cell with a membrane, and Bernstein developed the details of this 

 idea. No one doubts that the muscle is a concentration cell, but 

 the opponents of Bernstein's hypothesis doubt that a membrane 

 has anything to do with it, since concentration cells may be made 

 without membranes. But the emf of the current of injury of a 

 fresh muscle is from 40 to 80 mv and no concentration cell with- 

 out a membrane has been known to give such a high emf unless 

 it contained strong acids or alkalis, which are incompatible with 

 life. There seems to be no valid evidence against, and much for, 



