THE NERVOUS SYSTEM 177 



Man is surrounded by noci-associations, and he 

 is forever attempting to reach a state of anoci-asso- 

 ciation. An example of this is the attempt made by 

 a body when infected to produce an anti-toxin. 

 Under certain conditions as a result of fear, 

 worry, physical injury, infection, hemorrhage, ex- 

 cessive muscular exertion, starvation, insomnia 

 an excessive amount of energy, stored in the form 

 of potential energy, is discharged; this "excessive 

 conversion of potential into kinetic energy in re- 

 sponse to adequate stimuli" leads to shock. Such 

 is the "kinetic theory of shock," which further 

 states that the lesions of shock are to be found in 

 the cells of the brain, in the liver, and what inter- 

 ests us most in this chapter in the adrenals. 



"In our laboratory," writes Dr. Crile, "we found 

 cytologic changes in the adrenals in exhaustion 

 from any cause, including insomnia ; these changes 

 being more marked in the cortex than in the me- 

 dulla. Apparently adrenaline alone can cause the 

 brain greatly to increase its work. By cross-circu- 

 lation experiments, we have found that adrenaline 

 causes increased activity of the central vasomoter 

 mechanism. Not only can adrenaline, as Cannon 

 has shown, cause all the basic phenomena of exer- 

 tion, emotion, infection, etc., but it also causes 

 brain cell lesions identical with those produced by 



deaths, a mortality rate of one per cent., and among the last 500 

 ligations, two deaths." 



