364 MAN --AN ADAPTIVE MECHANISM 



The electric mechanism we have thus far described is 

 wonderfully adapted to the transformation of energy 

 and the elimination of the waste matter resulting from 

 that activity ; it responds quickly to every adequate 

 stimulus ; but still is a mechanism which responds at the 

 same rate for all seasons of the year, for all phases of life t 

 for all moments of those phases; but such a mechanism 

 is not yet a complete adaptive mechanism. 



Many periods in the life of the organism require 

 the expenditure of energy at a much higher speed 

 than is required at other periods. In certain seasons 

 of the year, for example, an increased expenditure of 

 energy is needed for adjustment to food supply and 

 climate. In like manner, there are periods of physi- 

 ological adjustment, such as adolescence, the period of 

 reproduction, courting and mating, and pregnancy; 

 periods requiring sustained physical efficiency, such as 

 the long chase ; periods of intense metabolic activity 

 for maintaining the chemical purity of the body, as 

 in infection and auto-intoxication. At such times 

 of " forced draft " on the bodily energies, there is re- 

 quired an organ -that will speed up the activity of the 

 whole electro-chemical mechanism for the transforma- 

 tion of energy ; an organ the secretion of which will act 

 primarily upon the brain, so modifying it that the 

 threshold to all stimuli will be lowered, in order that 

 the brain may drive the body with increased force, and 

 the total output of energy may be constantly augmented. 

 In distinction from the fleeting action of the secretion 

 of the adrenals, the action of the secretion of such an 

 accelerating organ should be slower, steadier and 

 more persistent in its effect. 



