15 

 of an early method was necessary and this took plaoe as 



learning progressed. Often, however, a difficult method 

 which had been learned seemed to persist, in spite of the 

 fact that an easier and more convenient one could be 

 learned. Such a difficult method prevailed for a time 

 only, and then for some unaccountable reason, disappeared 

 and the easier method of raising the latch with the snout 

 was adopted. 



The data obtained from experiments with the latch 

 box are found in Tables I-a, I-b and I-c. Table I-a shows 

 the number of trials each rat had in order to learn the 

 problem when given one trial daily, Table I-b for three 

 trials, and Table I-c for five trials. The time for each 

 trial is given in minutes and decimals of a minute. The 

 averages for each trial for all rats and also averages 

 for males and females are found at the bottom of the tables 

 At the end of each table are the retention tests and their 

 averages. It will be noticed that some rats were tested 



