33 

 still remain. 



THREE P SO?. 



Since it was found that one trial daily, or at greater 

 intervals when one problem was offered, was most economical 

 in the number of trials.it was then suggested that three 

 problems be given in succession, with one, three and five 

 trials. The latch box, maze and inclined plane box were 

 worked concurrently and always in the order named. With 

 all three problems when one, three or five trials were 

 given, a total of fifty- four rats were used. In the be- 

 ginning, it was thought that the rats, which would have 

 five trials daily for each problem, a total of fifteen 

 trials for the three problems, could not stand the 

 strain of so many successive trials, but this did not prove 

 true. The rats stood the tests well from the very first 

 and no indication of fatigue or apathy was at any time 

 noticable. The rats were a hardy strain similar to 

 those employed with the latch box and were at all times 



