1914] CRILE— THE KINETIC SYSTEM. 279 



mediately after the expiration of lOO hours of wakefulness, others 

 after varying intervals. 



Histological studies were made of every tissue and organ in the 

 body. Three organs, the brain, the suprarenals, and the liver, and 

 these three only showed histologic changes. In these three organs 

 the histologic changes were marked, and were almost wholly repaired 

 by o\ie seance of sleep. In each instance these histologic changes 

 were identical with those seen after physical exertion, emotions, 

 toxins, etc. It would appear, then, that these three organs take the 

 stress of life — the brain is the battery, the suprarenals the oxidizer, 

 and the liver the gasoline tank. The clear-cut insomnia experiment 

 corresponds precisely with our other brain-suprarenal observations. 



With these three kinetic organs we may surely associate also the 

 " furnace," the muscles in which the energy provided by the brain, 

 suprarenals and liver, plus oxygen, is fabricated into heat and motion. 



Benedict in his monumental work on metabolism has demonstrated 

 that in the normal state, at least, variations in the heart beat parallel 

 variations in metabolism. He and others have shown that all energy 

 of the body, whether evidenced by heat or by motion, is produced in 

 the muscles. In the muscles then, we find the fourth vital link in the 

 kinetic chain. The muscles move the body, circulate the blood, 

 effect respiration, and govern the body temperature. They are the 

 passive servants of the brain-suprarenal-liver syndrome. 



Neither the brain, the suprarenals, the liver, nor the muscles, 

 however, nor all of these together, have the power to change the rate 

 of the expenditure of energy ; to make possible the increased ex- 

 penditure in adolescence, in pregnancy, in courting and mating, in 

 infections. No one of these organs, nor all of them together, can 

 act as a pacemaker or sensitizer. The brain acts immediately in 

 response to the stimuli of the moment; the suprarenals respond in- 

 stantly to the fickle brain and the effects of their actions are fleeting ; 

 the liver contains fuel only and cannot activate, and the muscles in 

 turn act as the great furnace, in which the final transformation into 

 available energy is made. 



Another organ — the thyroid — has the special power of govern- 

 ing the rate of discharge of energy; in other words, the thyroid is 

 the pace-maker. Unfortunately, the thyroid cannot be studied to 



