228 



E. C. MACDOWELL AND E. M. VICARI 



TIME PER TRIAL 



FREQUENCY DISTRIBUTIONS OF AVERAGES FOR EACH RAT 

 TESTS , CONTROLS 



TEST AVERAGES ^ CONTROL AVERAGES ▼ 



.FIRST HALF TRAINING 



Fig. 2 Frequency distributions of the averages for each rat for time per trial, 

 based on six different groupings of the trials. The broken lines are the tests; 

 the solid lines, the controls. Units on the base line are seconds, units on the 

 vertical scale are numbers of rats. 'Completes,' 'incompletes,' and 'failures' 

 are used with the males and females in all strains. 



