68 



el by the young in comparison with the old. Certainly the be- 

 havior of the old animals wlien in the maze is much more deliber- 

 ate than that of the young ones, and the writer beliuvea that 

 if SlonaJcer had possessed some means of measuring the amount 

 of activity per unit of time he would have found the young far 

 more active than the old. 



In Table VIII is given the average speed for each group 

 for the 1st, 2nd and ICth trials, the tv;o trials immediately 

 preceding the last six, and the last six trials. The increase 

 of speed from the first to the 2nd trial is considerable except 

 in the 200-day group where there is a decided decrease. The 

 gain from the 2nd to the 10th trial is great except for the 

 3C0-day group where it is comiaratively small. From the tenth 

 trial to the two preceding the last six the gain for the 200 

 and SCO-day groups is greater than for the 25 or 65-day groups, 

 and from these two trials to the last six trials the gain is 

 again greater for the 200-day rats. This gives a slight indi- 

 cation as to where the most rapid learning occurs. A full set 

 of tables showing the speed for every trial of each grouj would 

 be necessary for an adequate discussion of the question, but 

 from the present incomplete data it appears that the learning 

 in the two younger groups is most rapid during the early stages, 

 while for the older groups it is more rapid during the later 

 trials. Especially is this true of the 300-day group, the in- 

 crease in speed being very gradual during the first ten trials 

 then more than doubling from the tenth to tl:e two immediately 

 preceiing the last six. In general, speed, for the separate 

 trials tabulated, decreased with age which accords with our 



