O'SHEA — ASPECTS OF MENTAL ECONOMY. 49 



living tissue while engaged in work. Now, it may be readily 

 inferred that the phenomenon of augmented cerebral circula- 

 tion during vigorous intellectual or emotional activity is identi- 

 cal in principle with the muscular phenomenon just noted. Cor- 

 roborative testimony in proof of this energeic dependence of 

 mind upon cerebral cells is afforded by the observations of 

 physicians 1 who maintain that certain toxic products of nerv- 

 ous action increase parri passu with intensified intellectual or 

 emotional activity. Mosso's demonstration of a distinction be- 

 tween muscular and neural fatigue 2 requires for explanation 

 the assumption that nervous as well as physical action results 

 in the accumulation of a sort of debris in the system, which 

 is undoubtedly nothing but worn-out or degraded nerve sub- 

 stance, and which may heap up to such an extent as to dis- 

 turb the normal functions of the neural mechanism. Especially 

 does it tend to throw out of gear the inhibitory apparatus, 

 paralyzing the fatigue sense, as some one has said, and thus 

 removing the natural checks to excessive physical or mental 

 exertion, when the organism continues in activity beyond the 

 safety limit. 



The experiments of Hodge 3 apparently show quite conclu- 

 sively, in the case of animals at any rate, that the activity of the 

 cell depletes the nucleus of its contents,, revealed in a gradual 

 shrinking while stimulation continues, as shown in Figs. 3 and 4. 

 ,This phenomenon, which he was able to detect while experi- 

 menting with a living cell under stimulation, was observed also 

 in the examination of animals at night after a day's activities, 

 pnd in the morning when they had passed a long period in 

 rest. In the first instance the nuclei of the cells were shrunken, 

 while in the morning they presented a repleted appearance, 



1 For instance, by Cowles : Neurasthenia and Its Mental Symptoms; Beard: 

 Neurasthenia, edited by Rockwell ; Mills: Mental Overwork and Premature Dis- 

 ease Among Public Men, Smithsonian Institute, No. IX of Toner Lectures. 



2 See for further discussion, p. 52. 



3 Some Effects of Electrically Stimulating Ganglion Cells, American Journal 

 of Psychology, vol. II, p. 376 et seq. ; and, Process of Recovery from Fatigue Oc- 

 casioned by the Electrical Stimulation of Cells of the Spinal Ganglia, Am. Jour, 

 of Psy., vol. Ill, p. 530 et seq. 



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