40 L. W. SACKETT 



sharpened for this occasion by giving him only half his cus- 

 tomary allowance of food the day before. The writer is not 

 aware that any other animals, subjects of experiments by psy- 

 chologists, have been as successfully employed for class demon- 

 stration as the porcupine. All except one of the animals in 

 this study have shown similar docility and composure under 

 cage conditions. Others may decide whether it indicates a 

 high or low^ order of intelligence, or W'hether it indicates any- 

 thing so general as that. 



The loo-day memory test showed much better retention than 

 the 50 -day test. The time for the first operation was i minute 

 and 31 seconds and for the second 20 seconds. Trials 3 to 

 10 were somewhat irregular but all due to his failure to operate 

 locks sufficiently when he had attacked them. The average 

 time for the 10 operations was 28±i3 seconds which, never- 

 theless, taken with the behavior of the animal, gave four ex- 

 perienced observers the impression that the porcupine had 

 retained the association well but had lost chiefly in dexterity. 

 There are several obvious explanations for the superior memory 

 of the 100-day test over the former 50-day test, (i) The 50-day 

 test was really 80 days after first perfecting the association. He 

 had been tested with the apparatus twice at 13 days and 10 

 times at 30 days. (2) The second relearning for purposes of 

 class demonstration may have had special significance as to the 

 importance of repetition in facilitating retention. (3) It must 

 also be remembered that during all of those 80 days, No. 3 was 

 busy with other lines of experimentation, while during the last 

 100 days no experiments were attempted. This would indicate 

 that the conditions of normal cage life were not so distracting 

 as the controlled problems of experimental work. This corro- 

 borates the finding of other experimenters with various other 

 animals where memory has been tested during periods of activ- 

 ity and corresponding periods of inactivity. 



In training porcupine No. 7 to operate this box a variation 

 was made in the method. This plan was to add the new parts 

 in succession but to retain the first ones in combination as 

 they were learned. The plan would probably have worked well 

 had the animal not refused to pull the plug. Even when it was 

 coated with food he would catrefully gnaw off the food and leave 

 the plug set. Day after day for nearly two weeks he taxed the 



