232 KANSAS UNIVERSITY SCIENCE BULLETIN. 



that some change had taken place. It never materially dis- 

 turbed his reactions. Be. reported that the three sounds were 

 kept in mind, but were not clearly distinguished, that is, each 

 sound had a number for her, and she knew whether it had 

 been given as the reaction sounder, but otherwise the three 

 were confused. For Do. the extra three sounds were generally 

 scarcely more clearly present than any other slight noise that 

 might occur, and when one was signaled as the sound to be 

 discriminated, it came as a sound that had not been heard 

 during the previous minute. Only one subject, a student whose 

 results were too meager to be reported, found that he kept all 

 four sounds clearly in mind. If he failed to do so he became 

 confused. 



The two types of physical work used with the sounder test 

 should be considered separately. The "harness" represents a 

 strenuous type of work that generates fatigue quickly. The 

 subject is somewhat out of breath, feels weak in the knees, 

 and is more or less in a tremor all over. The long walks 

 develop fatigue much more slowly, and there is more time 

 for a gradual readjustment generally. Moreover, physical 

 fatigue produced by walking has more time, if time is needed, 

 in which to affect mental ability. Two subjects walked, and 

 one of them was used in the work with the harness. So there 

 is a slight basis furnished for a comparison of the two kinds 

 of physical fatigue. After the walks S. shows an unusual 

 decrease in power to react correctly; this condition is fairly 

 constant throughout the series. In only one test has he shown 

 improvement in both the per cent of omissions and in the 

 per cent of errors ; in one other case he has improved in 

 omissions but failed in errors. Usually a change in one form 

 of mistake is paralleled by a similar change in the other form. 

 This is not true with Do.'s results. The two forms are more 

 inclined to fluctuate independently. His failure after walking 

 is also not so marked as in S.'s results. It will be noticed that 

 the per cent of mistakes in both tests for Do. on the last fatigue 

 clay is extremely low. It is difficult to account for this unusual 

 drop. It was not the fault of the sounders, for S. was tested 

 at the same hour, and his results are normal. The sounders 

 were operated a little faster for Do. than was usual, and it may 

 be that this acted as a stimulus to greater activity, or the fact 

 that the sounds came closer together may have made them 



