58 BULLETIN OF THE UNIVERSITY OF WISCONSIN. 



as Kraeplin, 1 Burgerstein, 2 Sinclair, 3 and others. 4 These re- 

 sults will certainly not awaken surprise in any one who has ob- 

 served the sharpness of his own senses at different hours during 

 the day, and under varying circumstances with respect to fa- 

 tigue. One may hear those about him say frequently something 

 like the following : "I derive much greater benefit from visiting 

 an art gallery in the morning than at 4 o'clock in the afternoon ;" 

 or "I find more pleasure in going out into the fields and coming 

 in contact with nature in the morning hours than later in the 

 day, for I see more, or at least I appreciate more; everything 

 has a meaning for me now which is not apparent at other times. 

 There are details and harmonies in sound, in color, and in form, 

 which I apprehend when I am refreshed but which I miss when 

 my mind is tired." And the rationale of this is not obscure. 

 It is not that there is less of beauty and richness in nature in 

 the late hours of the day, nor that the visual or auditory sense 

 organs are incapable of receiving stimulations therefrom; but 

 the structures in the brain through which interpretation pro- 

 ceeds, because of the wastedness of their substance, if one may 

 so speak, and the accumulation of obstructive materials, hinder 

 the efficiency of the mind's action. Doubtless every student has- 

 noticed that when his energies are at a low ebb, Whether abnor- 

 mal in persisting throughout the entire day, or week, or month, 

 or whether occurring only at intervals in the daily rhythm, yet 

 in any case his perceptions become less keen and accurate, and 

 he grows dull in all work that depends upon clearness of per- 

 ception, as in the apprehension of forms in language, to some 

 extent in mathematics, and to a considerable degree in the me- 

 chanic arts, not to mention other studies. 



The senses are not the only nor the principal losers when the 

 mind is over-wearied. Memorv, both in its retentive and recol- 



1 A Measure of Mental Capacity, Pop. Sci. Mo., vol. XLIX, p. 756. 



2 Quoted by Kraeplin, loc. cit. 



8 Loc. cit. 



4 Since the above was written, the writer has read La Fatigue InteUectuelle, 

 by A. Binet and V. Henri, in which the propositions herein set forth are in the 

 main substantiated. See for a recent summary of studies upon this point, Kotel- 

 mann, School Hygiene, chaps. VII and VIII. 



