30 
CURT P. RICHTER 
equivalents in miles. The dotted ordinates indicate that no 
records were taken on the day preceding. 
It is seen that for the first day in the drums—none of these 
rats of course had ever been in the drums before,—the youngest 
rat 1 begins with by far the highest number of revolutions (7000) 
while the second and third youngest come next with 2500 revolu¬ 
tions, the fourth next with 1700, the fifth next with 1200, then 
the last with 30. This same relation holds for the rate of in¬ 
crease in the daily record for the first part of the experiment. 
Fig. 16. Curves Showing Schematically the Results of the Revolving 
Drum Experiment 
This daily increase as well as the general relation of the records 
of these animals is shown schematically in figure 16. 
Were the higher number of revolutions made by the younger 
rat due to greater activity then it should continue to make 
higher scores throughout the experiment. But it failed to do this. 
It was overtaken first by the 100 day rat and then by the 210 day 
rat. This same thing happened in turn to the 100 day rat. It 
is also finally overtaken by the 210-day animal. The higher 
number of revolutions at the beginnning of the experiment and 
