198 MAN --AN ADAPTIVE MECHANISM 



seen that in rage and fear a physiological preparation 

 for supreme motor efficiency is secured by an increased 

 output of adrenin, resulting in a mobilization of energy 

 compounds, a diversion of the blood stream to the 

 fighting apparatus and a diminution of fatigue. The 

 significance of this point should not be overlooked. 



Adrenin performs all the functions that are per- 

 formed by the sympathetic nervous system except one. 

 Adrenin raises the blood pressure, accelerates the 

 respiration and slows the heart action, governs the 

 output of glycogen from the liver, inhibits intestinal 

 contractions, widens the alveoli of the lungs, increases 

 oxygen combustion in the muscles, dilates the pupils, 

 causes uterine contractions, erection of the hair and 

 sweating. We have shown that it mobilizes the Nissl 

 substance in the brain and directly activates the brain. 

 In short, adrenin causes all the leading phenomena 

 which are the invariable accompaniments of the pro- 

 duction of heat and motion in muscular action, infec- 

 tion or emotion, and which are presumably outward 

 manifestations of the processes by which these trans- 

 formations of energy are effected. The only function 

 of the sympathetic nervous system which adrenin does 

 not perform is stimulation of the adrenals themselves 

 to greater activity. 



Interdependence of the Brain, Thyroid, Adrenals, Liver 

 and Muscles 



We have seen that the brain and the muscles are 

 interdependent in the production of both heat and 

 motion, since the elimination of either causes a diminu- 

 tion or loss of these processes. We have seen that the 



