THE NERVOUS SYSTEM 161 



even in the light cases the 'capability of reacting 

 to strong stimuli' is lost. The speech may be mark- 

 edly slowed, 'as if/ writes the [late] Dr. Meltzer, 

 'the speech mechanism were frozen in.' Charcot, 

 the French neurologist, compares such patients to 

 hibernating animals. 



"The English Commission found among the 

 myxedema patients investigated by them that 18 

 suffered from illusions, 16 from hallucinations, and 

 16 from frank psychosis. The psychoses belong to 

 various types, although the melancholoid condi- 

 tions predominate. The symptoms of the psychosis 

 often develop simultaneously with those of myxe- 

 dema, and vanish after thyroid therapy has been 

 instituted, to reappear again when the therapy is 

 discontinued." 



The researches of Cannon, referred to above, 

 tend to show that the adrenals and more particu- 

 larly one of their hormones, adrenaline, are 

 closely associated with the mental state of the per- 

 son. The close connection between the action of 

 adrenaline and that of the sympathetic system has 

 been discussed in the chapter on the adrenals. We 

 must now take up Cannon's work in some detail. 



The researches of Professor Cannon. Professor 

 Cannon, of Harvard, working in conjunction with 

 a number of his pupils ( among whom must be men- 

 tioned de la Paz, Shohl, Wright, Washburn, Ly- 

 man, Nice, Gruber, Osgood, Gray and Mendelhall), 



