346 'Journal of Co7nparative Neurology and Psychology. 



TABLi: II. 



Representing four single days activity at the ages indicated. 



The tabulation in Table II is intended to show the work, the 

 number of periods of rest and activity, etc., during four of the 

 days of the experiment. The table is self-explanatory and needs 

 no further comment. From this it is observed that the rats become 

 more regular in their activity toward the end of the experiment. 

 The daily records show this much more prominently than is seen 

 in this tabulation. The reason for this is no doubt due to their 

 becoming accustomed to the environment. 



This experiment shows that the very young rat is more active 

 than the old one and that somewhere between these two extremes 

 the period of greatest activity is to be found. According to these 

 results the period of greatest activity for No. 3 was at the age of 

 87 days. The period of greatest activity for Nos. i and 2 had not 

 yet been reached. No. 4 was decidedlv on the decline from the 

 very beginning of the experiment. The marked discrepancy 

 between No. 2 and No. 3, which are so nearly the same age, is 

 certainly due to individual variation. 



