192 BULLETIN OF THE UNIVERSITY OF WISCONSIN. 



long run accomplish more than if it be held continuously regard- 

 less of cerebral wear and tear. Efforts have been made to as- 

 certain the span during which attention can be profitably held 

 to a subject; but as in the case of the amount of work which can 

 be done, the result must be purely relative ; it depends upon the 

 subject and upon the individual. It is thought by some, though, 

 that in general fatigue intervenes after twenty minutes concen- 

 trated effort in the early years and sixty minutes or thereabouts 

 in maturer life. 1 It is probable, however, that a vigorous adult 

 possessing a well organized brain can apply himself to one sub- 

 ject for a longer period than an hour. Experience and the prin- 

 ciples of neurology both warrant the hypothesis that energy gen- 

 erated in one part of such a brain may be utilized readily in 

 carrying forward work in other regions. 2 But the association 

 fibers which make possible the easy transmission of energy from 

 one cell to another do not apparently attain their complete de- 

 velopment until about the age of thirty-three, as is indicated in 

 Eig. 17. 



Now if the assumption be true that the associative fibers serve 

 as energy-carriers between the various cerebral departments, and 

 these fibers are maturing constantly until middle life, then it 

 follows that the Senior in the University should, other things 

 being equal, be able to apply himself with profit for longer 

 periods than the Freshman. But it is certainly impossible in 

 the present state of our knowledge to say just how long should 

 be the study periods of either the Senior or the Freshman. All 

 we are warranted in saying, which is far from as definite as can 

 be desired, is that attention should be concentrated upon a single 

 subject at a time and held to it until the approach of fatigue, 

 when it should be released. If the same study is to be contin- 

 ued, a break of ten minutes passed in moderate physical activi- 

 ties will aid in the removal of worn out materials from the brain 

 and in securing a fresh supply of blood in the cerebrum. It is 



2 See Ped. Sem., June, 1892, pp. 64 and 65. 



2 Flechsig: Oehirn und Seele, presents strong evidence in favor of the view 

 that energy generated in one part of the brain may be put to use in remote reg- 

 ions. See also Curtis: Inhibition; Ped. Sem., Vol. VI, No. 1, for a valuable dis- 

 cussion of the subject. 



