I9I4.] CRILE— THE KINETIC SYSTEM. 269 



would interfere with bacterial growth. With each rise of one degree 

 centigrade the chemical activity of the body is increased ten per cent. 

 In acute infections there is aversion to food and frequently there is 

 vomiting. In fever, then, we have a diminished intake of energy, 

 but an increased output of energy — hence the available potential 

 energy in the body is rapidly consumed. This may be an adapta- 

 tion for the purpose of breaking up the foreign protein molecules 

 composing the bacteria. Thus the body may be purified by a che- 

 mical combustion so furious that frequently the host itself is de- 

 stroyed. The problem of immunity is not considered here. 



As to the mechanism which produces fever, we postulate that it 

 is the same mechanism as that which produces muscular activity. 

 Muscular activity is produced by the conversion of latent energy into 

 motion, and fever is produced largely in the muscles by the conver- 

 sion of latent energy into heat. We should, therefore, find similar 

 changes in the brain, the suprarenals, the thyroid, and the liver, what- 

 ever may be the purpose of the conversion of energy — whether for 

 running, for fighting, for the expression of emotion, or for combating 

 infection. 



We shall first present experimental and clinical evidence which 

 tends to show what part is played by the brain in the production of 

 both muscular and febrile action, and later we shall discuss the parts 

 played by the suprarenals, the thyroid, and the liver. 



Histologic Changes in the Brain-Cells in Relation to the 

 Maintenance of Consciousness and to the Production 



OF THE Emotions, Muscular Activity and Fever. 

 We have studied the brain-cells in human cases of fever, and in 

 animals after prolonged insomnia; after the injection of the toxins 

 of gonococci, of streptococci, of staphylococci, and of colon, tetanus, 

 diphtheria and typhoid bacilli ; and after the injection of foreign 

 proteins, of indol and skatol, of leucin and of peptones. We have 

 studied the brains of animals which had been activated in varying 

 degrees up to the point of complete exhaustion by running, by fight- 

 ing, by rage and fear, by physical injury and by the injection of 

 strychnia. We have studied the brains of salmon at the mouth of 

 the Columbia River and at its headwater ; the brains of electric fish, 



