4 HELEN B. HUBBERT 



by the young (nine month) individuals than by the old ones, 

 whose age is not given. 



Watson 1^ in his Animal Education, discusses work both on 

 habits involving simple motor ability and on those requiring 

 skill in manipulation. He concludes that " a young rat will 

 solve for the first time more quickly than a mature rat any 

 problem conditioned on mere random activity, but that a prob- 

 lem involving associative activity and manipulation is more 

 easily solved by the older animals." He found that with the 

 simple saw-dust box the average time of entrance for the old 

 rats was 85.50 minutes, while that for the young ones was 6.87 

 minutes and says further, " there is a gradation in the number 

 of useless movements made by rats at different ages. At thirty- 

 five days of age, when physical activity appears to have reached 

 its highest stage, the percentage of useless movements is largest. 

 As the rats grow older, this superabundant activity disappears, 

 and in its place comes direction of activity." 



To summarize the main points in this brief historical survey, 

 we may note: 



First: — That there is disagreement as to the age of greatest 

 activity, Slonaker putting it first between eighty-seven and one 

 hundred twenty days, and later at ten months for the males 

 and twelve and a half months for the females, while Watson 

 believes it' to be at about thirty-five days; 



Second: — That Yerkes finds the labyrinth habit more easily 

 learned by the old dancers than by the young, while if Watson's 

 interpretation is correct the reverse should be true; 



Third: — Yerkes concludes that the female is superior to the 

 male in learning the labyrinth. 



APPARATUS AND PROCEDURE 



Aibiino rats were chosen as subjects in this investigation, for 

 several reasons: Slonaker, Watson and Yerkes worked with 

 rodents, and we desired to compare our results with theirs. 

 Nearly two hundred animals were required for actual experi- 

 mental work and many more than that had to be kept on hand 

 to provide for replacing any which might become unfit for work, 

 and to allow for the usual losses through death and sickness. 

 It has been found that white rats are easier to breed, handle, 



" Watson, J. B. Animal Education. University of Chicago Press, 1903. 



