ELECTRO-CHEMICAL PHENOMENA 363 



In the brain is created not only the electric force 

 that drives the muscles to fabricate heat and motion, 

 but also the electric force that activates certain 

 muscles to assist in the elimination of the acid by- 

 products of energy transformation. To this end, a 

 nerve runs to every muscle which takes part in this 

 elimination, just as to every muscle which takes part 

 in the act of transforming energy. The number of 

 muscles actually engaged in the gross adaptive act are 

 comparatively few; but the muscles engaged in the 

 simultaneously increased actions of circulation, respira- 

 tion and the elimination of waste matter are many. If 

 a separate impulse were required to go from the brain 

 to every one of the tiny muscles in the walls of the 

 blood vessels and to every cell of the glandular tissues 

 cooperating in the adaptive response, a vast nervous 

 system would be needed. 



To obviate this need, there has apparently been 

 evolved an organ, itself under the control of the brain, 

 the secretion of which is capable of mobilizing all the 

 organs and tissues in accordance with the part each is 

 to play in the response. The secretion of this organ 

 increases the action of the brain, raises the blood pres- 

 sure and accelerates the circulation. It increases the 

 efficiency of the eye by causing the eye to protrude and 

 the pupil to dilate. It probably increases still more the 

 difference in potential at the myoneural junction, and 

 facilitates the neutralization of the acids resulting from 

 energy transformation. The action of this secretion, in 

 accordance with what would be most useful in the 

 changeful environment, is quick almost instantane- 

 ous ; powerful, but fleeting. This secretion is adrenin. 



