326 MAN AN ADAPTIVE MECHANISM 



well-expressed disease phenomena in the senile and in 

 infancy. The aged, the infant and the victim of 

 general paresis show but few symptoms of disease 

 because of the fact that in senility the brain is so de- 

 teriorated, and in infancy so undeveloped, that the 

 cerebral mechanism of associative memory is inactive, 

 hence pain and tenderness, which are among the oldest 

 associations, are lacking. Senility and infancy are 

 by nature normally narcotized. The senile is passing 

 through the twilight into the night, while the infant 

 is emerging from the shadows of dawn into the day. 

 Hence it is, that in the extremes of life the diagnosis 

 of injury and disease is subject to special difficulties. 

 At such times, as regards symptoms, the entire body 

 is as silent as the brain, the pericardium, the medias- 

 tinum and other normally symptomless areas. For the 

 same reason, when a patient, seriously ill with a pain- 

 ful disease, turns upon the physician a glowing eye 

 and an eager face, and remarks how comfortable he 

 feels, then the end is near. The mechanism by which 

 the transformation of energy is accomplished has run 

 down. Energy is no longer available to register the 

 results of stimulation in pain any more than in motion. 

 The most convincing evidence of this hypothesis, 

 however, is found in the prevention of postoperative 

 pain by the use of anociation. According to our hy- 

 pothesis (explained at length in Chapter IX), post- 

 operative pain is due to the state of low threshold 

 established in the brain as a result of intense or repeated 

 injurious impulses. The site of postoperative pain 

 is not in the traumatized field, but in the brain. If 

 the traumatic impulses are prevented from reaching 



