CHAPTER IV 



ELECTROMOTIVE ACTION IN MUSCLE 



THE potential energy stored as chemical force in muscle, as in 

 all other living tissue, yields in general three forms of vital 

 energy, i.e. mechanical work (mass motion) and molecular motion 

 in heat and electricity. In so far as muscle-cells proper are 

 concerned it is the first of these which plays the weightiest 

 part, and must be regarded as their characteristic function. The 

 production of heat is not nearly as conspicuous in comparison, 

 although in warm-blooded animals it also plays an important part 

 in the economy of the organism. Finally, the development of 

 electricity, which alone concerns us in the present connection, 

 falls, with a few negligible exceptions, so far behind the other 

 two forms of living energy that the most refined methods and 

 delicate instruments are needed in order even to ascertain its 

 existence. That, notwithstanding such disadvantages, this chapter 

 of electro-physiology should be among the best known and most 

 carefully worked out in Physiology is mainly due to the fact that 

 since the discovery of the marvellous action of the electrical 

 current upon excitable parts of the body, and the epoch-making- 

 controversy between Galvani and Volta, the idea that the mys- 

 terious phenomena of muscular and nervous activity were in some 

 degree related to the no less obscure force of electricity never 

 wholly vanished. Although the conviction subsequently obtained 

 that the force which travels from nerve to muscle (the " nervous 

 principle ") is not in itself electricity, the rapid additions to the 

 theory of electromotive action in certain animal tissues, and in 

 muscle and nerve in particular, kept alive the presumption that 

 these manifestations cannot be without import for the function of 

 the parts in which they are exhibited. 



