GROWTH AND CHEMICAL PURITY 265 



the kinetic system transforms energy for the purpose of 

 maintaining the body at an optimum chemical standard 

 and at an optimum bulk. Our evidence for this state- 

 ment rests upon the fact that most of the metabolic 

 activities which result in the maintenance of the 

 chemical purity of the body are attended by the same 

 phenomena, the same functional and histological 

 changes in the brain, adrenals and liver that are 

 produced by other activations of the kinetic 

 system. 



Were not some mechanism in the body adapted to 

 regulate the disposition of food intake, to limit the 

 storage of the digestion products of proteins, carbohy- 

 drates and fats, the normal organism in the midst of 

 an abundant food supply would, like sand dunes, con- 

 tinually increase in bulk. That there is such a regu- 

 lating mechanism, and that this mechanism is the 

 kinetic system, is suggested by the facts about to be 

 presented, which show that intravenous injections of 

 excessive doses of amino acids, of glucose, of alcohol 

 or of fatty acids result in : (1) an increased meta- 

 bolic activity, i.e., increase in output of calories; 

 (2) an increased activity of the organs of the kinetic 

 system, resulting in functional and histologic changes 

 identical with those produced by running, fighting, 

 emotion or infection (Figs. 62, 63, 64) ; and (3) a di- 

 minished power of the kinetic system to respond to 

 other adequate stimuli. 



(1) Metabolism: Rubner, Benedict, Lusk, Du Bois 

 and others have shown, by calorimetric methods, that 

 protein injection is followed by an increased pro- 

 duction of calories. This is the so-called mass action 



