HABIT FORMATION IN THE ALBINO RAT 47 



tance in learning the problem than did the females, while their 

 speed was slightly higher. This conclusion is at variance with 

 that of Yerkes regarding the dancer, he having found the females 

 superior to the males in learning the labyrinth. In the matter 

 of final efficiency as evinced by the absolute time, the females 

 are superior to the males at all ages except three hundred days 

 when the two records are practically equal. The general aver- 

 age shows this to be the one point wherein the record for the 

 females is better than that for the males. 



The mean variation from the time average is less for the 

 males at all ages, their distance variation is less at sixty-five 

 and three hundred days. The general average shows the small- 

 est time variation for the males and the smallest distance varia- 

 tion for the females. These results do not agree with those of 

 Yerkes on the dancer. His ten month (300 day) dancers learned 

 the labyrinth more rapidly, the number of trials required being 

 the measure of learning, than those one to two months old 

 (30-60 days) while there was no difference in the learning abil- 

 ity of the females at the two ages. My twenty-five and sixty- 

 five day rats of both sexes formed the maze habit considerably 

 more rapidly than the three hundred day animals. 



The fact that in the number of trials, total time and total 

 distance required to learn the problem, the males at sixty-five 

 days are superior to those at twenty-five days while the reverse 

 is true of the females, suggests the possibility that the capacity 

 for habit formation develops earlier in the females than in 

 the males. 



Day and Night Work 



It has been stated by Slonaker, and is generally believed, 

 that the albino rat is nocturnal. With a view to testing this 

 matter certain rats in the twenty-five and two hundred day 

 groups were run always in the day time, certain others always 

 at night. The averages for the day and night rats were ob- 

 tained in the same manner as the group averages, from Tables 

 A and C. 



The twenty-five day rats run during the day were numbers 

 1, 2, 4, 5, 6, 15, 16, 17, 19, 20, 21 and 24, seven of which were 

 males and six females. Those run at night were numbers, 8, 

 9, 10, 11, 12, 13 and 14, two males and five females. The 



