DOCKERAY : PHYSICAL FATIGUE AND MENTAL EFFICIENCY. 227 



son. If we examine Tables lb and 116, we find that after rest 

 he shows a decidedly greater decrease in both speed and ac- 

 curacy with the multiplication tests than with the addition 

 test. As multiplication is a much more difficult process than 

 addition as the two were employed, we may assume that the 

 mental fatigue induced by the first test has not entirely dis- 

 appeared at the end of the twenty-minute rest interval, or 

 that his interest is not so great. It is true that the five- 

 minute periods of the first tests, as given in Table Ila, 

 do no indicate any accumulation of fatigue, but this may 

 be obscured by practice effects or overcome by inertia 

 effects. The details of tables la, Ila and Ilia (pp. 213-222) 

 will be discussed later. After eighteen laps he does better 

 than after rest, but not so much better as in the addition 

 test. After twenty-seven and thirty-six laps he shows marked 

 improvement, though after thirty-six laps speed (on the aver- 

 age) has given way somewhat to an unusually large increase in 

 accuracy. A large part of this variation is due to the test 

 following the thirty-six laps on the second day of the series, 

 though the general tendency for decreased speed and increased 

 accuracy is seen throughout the series. 



Just where in the total series the tests with the cross- 

 country running should be considered to belong is difficult to 

 determine. These runs were made over hills and uneven 

 paths, usually in a strong wind. Ba. believed he was more 

 fatigued than when he ran two miles (thirty-six laps) on the 

 track, but other runners claimed that they always found it 

 less fatiguing than the same distance indoors, providing they 

 ran more slowly across country. Ba. in this series required 

 considerably more time than he did indoors for the same dis- 

 tance. It was expected that the series would be completed 

 by a series of five-mile runs across country, but a change in 

 Ba.'s plans made it necessary to abandon this plan. It is 

 necessary, therefore, to consider this series separately. The 

 results would indicate that the fatigue was a little more than 

 that produced by eighteen laps indoors. 



In the tests with Co. and De. we have a different set of 

 conditions. The time spent in physical work by these sub- 

 jects was the same in each (twenty minutes), but the amount 

 of physical fatigue produced was controlled by the type of 

 work performed. A much smaller, isolated group of muscles 



5 — Univ. Sei. Bull., Vol. IX, No. 17. 



