ELECTRO-CHEMICAL PHENOMENA 361 



The motor mechanism is readily apparent : the 

 nerve ceptors, contact, distance and chemical ; the 

 nerve fibers leading from these to the brain ; 

 the nerves leading from the brain to all muscles of 

 the body; the bones and joints; the muscles these 

 make up the motor mechanism. With properly ad- 

 justed electric stimulation of the various muscles by 

 means of a faradic battery, there is no doubt that, for 

 instance, the motor mechanism of a dog recently killed 

 could be made to run, to fight, to bark, indeed, to 

 perform every adaptive movement of the body. But 

 these movements would come to an end quickly. The 

 fuel stored in the muscles would soon be used up. The 

 waste products of energy transformation would speedily 

 choke the motor. An automatic mechanism, such as 

 man, must have an automatic arrangement for pre- 

 venting polarization of the brain battery, for renewing 

 the elements of the battery, for bringing to the muscles 

 new stores of energy and for taking from the muscles 

 the hampering waste matter. 



To serve certain of these ends blood has been evolved. 

 Blood floods every cell of the battery and every element 

 of the motor ; it carries replenishing stores of energy to 

 the brain and the muscles and brings back the waste 

 products. The mechanisms which prevent polarization 

 of the battery by maintaining the difference in poten- 

 tial, and change the rate of electric discharge and the 

 rate of fabrication of electricity remain to be pointed 

 out. 



Granting that in the normal state the battery is not 

 polarized, and that the necessary difference in poten- 

 tial exists, we may assume that the battery in the 



