356 11. A. KOCHER 



for comparison, and frequently the histological technic was faulty. 

 In explanation of the diverse changes described by these workers 

 as resulting from fatigue, it has been assumed that certain mate- 

 rials present in the nerve cells have been katabolized to form 

 energy for the nerve impulse, and that the using up of this 

 material during activity can be detected histologically by the 

 depletion of the granules (chromatic substance), changes in size 

 of cell and nucleus. In a long series of carefully controlled 

 experiments, I could find no evidence of any analogy between 

 the effect of activity in certain glands and activity in nerve cells. 

 In no experiment did the histological structure of the nerve cell 

 following activity show any constant deviation from that of the 

 corresponding resting cells of the controls. Some very sweeping 

 generalizations have been drawn from the conclusions of pre- 

 vious workers; namely, that fatigue, fear, shock and exhaustion 

 may lead to permanent damage and even disintegration of nerve 

 cells. Crile's present theory of surgical shock and of certain 

 aspects of Graves' disease, based essentially on these assunp- 

 tions, may be cited to show to what extremes these deduct ons 

 based on insufficiently controlled experiments of this kind have 

 led. 



SUMMARY 



The effect of various grades of activity on nerve cells was 

 studied in a series of fifteen separate experiments. The animals 

 used were dogs, cats, pigeons, sparrows, frogs, and rats. ii]very 

 experiment was carefully controlled by a resting animal of the 

 same species, of the same approximate age and size, and the 

 material from both given identical treatment, except for the 

 activity. The nerve cells studied were from the cruciate gyrus, 

 from the cerebellum, from the anterior horn of the spinal cord, 

 and from the dorsal ganglia. In one of the experiments over 

 thirty-five hundred nerve cells classified into thirteen types ac- 

 cording to histological characters were counted to determine the 

 relative frequency of characteristics which might be correlated 

 with grades of activity. There was no deviation from the nor- 

 mal in even the most advanced fatigue. Over a thousand cells 



