THE STUDY OF MUSCLE PHYSIOLOGY. 197 



the current should cause a muscular contraction. An equally 

 sudden alteration, a profound molecular effect, has been caused, 

 and this we must believe essential to the causation of a muscu- 

 lar contraction through the influence of a nerve. 



To use an illustration which may serve a good purpose if 

 not taken too literally, it is a well-known experience that one 

 sitting in a room in which a clock is ticking soon fails to no- 

 tice this regular sound : but should the clock stop suddenly or 

 as suddenly commence to tick very rapidly, the attention is 

 aroused, while a very gradual slowing to cessation or the re- 

 verse would have escaped notice. The explanation of such 

 facts takes us down to the very foundations of biology ; but 

 just now we wish only to elucidate by our own experience 

 how it is possible to conceive of a muscle being stimulated 

 by the molecular movements of nerve, or rather a change in 

 these. 



There are impqrtant practical aspects to this question. One 

 may understand why it is that electricity proves so ready a 

 stimulus, and is so valuable a therapeutic agent. It seems, in 

 fact, as will be learned later, to be capable of taking the place 

 to some extent of that constant nerve influence which we be- 

 lieve is being exerted in the higher animals toward the mainte- 

 nance of the regularity of their cell-life (metabolism). 



Pathological and Clinical.— It is believed that in the nerves 

 of a living animal body, the electrotonic condition can be in- 

 duced as in an isolated piece of nerve. Hence, the value of 

 the constant current in diminishing nerve irritability in neu- 

 ralgia and allied conditions. Apparatus of g^reat nicety of con- 

 struction and capable of generating, accurately measuring, and 

 conveniently applying electrical currents of different kinds, now 

 adds to the resources of the practitioner. But we are probably 

 as yet only on the threshold of electro-therapeutics. 



Electrical Organs. — Electrical properties can be manifested 

 by a large number of fishes; and the subject is of special theo- 

 retical interest. It is now established that the development of 

 electrical organs points to their being specially modified mus- 

 cles — tissues, in fact, in which the contractile substance has disap- 

 peared and the nervous elements become predominant and 

 peculiar. No work is done, but the whole of the chemical 

 energy is represented by electricity. Functionally an electric 

 organ (which usually is some form of cell, on the walls of 

 which nerves are distributed, inclosing a gelatinous substance, 



