138 MAN --AN ADAPTIVE MECHANISM 



voluntary impulse, and the organism experiencing fear 

 or rage are identical. The Marathon runner, like the 

 rabbit terrified by a dog, exhibits the phenomena of 

 increased blood-pressure and heart action, increased 

 respiration, rising temperature, profuse perspiration, 

 staring eyes, trembling limbs ; and if the activation be 

 sufficiently prolonged, muscular relaxation, dry mouth, 

 pallor, indigestion, prostration and finally the collapse 

 of every function. 



Further evidence of the identity of the muscular 

 activation in emotion and in physical exertion is found 

 in a study of the physiological and histological changes 

 caused by each. We have found also that intense 

 emotion causes increased H-ion concentration in the 

 blood, cerebrospinal fluid and urine. 1 



Histological Phenomena of Emotion 



If the emotions are expressions of motor activity, 

 which is itself dependent upon the driving power of 

 the brain, one would expect to find that emotion pro- 

 duces histologic changes in the brain-cells identical 

 with those produced by physical exertion. To test 

 this point, animals were subjected to acute fear and 

 to rage, some being killed immediately, others after 

 varying intervals of rest. In those killed immedi- 

 ately, the brain-cells showed an increase of Nissl sub- 

 stance and of the percentage of active cells ; while 

 the brain-cells of animals which had been allowed vary- 

 ing periods of rest showed uniformly a loss of Nissl sub- 

 stance, the percentage of active cells being decreased 



1 Drs. Menten, Rogers, Harrison and Crozier. 



