CANADA PORCUPINE 41 



patience of the experimenters. The lever was removed, the 

 plug was made smaller, then shorter, then longer. It was satu- 

 rated with food and the animal was starved for 48 hours to 

 induce him to put forth greater effort; but still he did not 

 attack it in the proper manner. Everything the animal did 

 resulted in failure so he became indolent and presented all 

 the pedagogical problems of the "dull individual." The plug 

 was wrapped in a cloth to make it soft but he would not do 

 the one thing necessary; viz., take hold of the plug with his 

 teeth and pull. At length, on the suggestion of Dr. Burnham, 

 a carrot was hollowed out and fitted down over the plug in 

 such a way that if the animal tried to take the carrot off the 

 box to eat it he would in that manner pull the plug. This 

 brought the first real success. He bit the carrot and pulled the 

 plug, the door opened striking the hind foot of the animal. 

 This so startled him that he released the carrot and then noticed 

 that the door w^as open. The next effort resulted in the same 

 experience. On the third trial he had shifted his position so 

 as to avoid the fall of the door and this time he attempted to 

 eat the carrot without pulling the plug. On the third day 

 following, however, he had mastered the problem as far as the 

 carrot-plug was concerned. When this carrot was removed he 

 again refused to pull the plug. The change was too great. The 

 carrot was restored but gradually trimmed smaller and smaller 

 till on the loth trial there was only a small piece tied on the 

 side of the plug with a string. This seemed to be sufficient 

 but the animal would always seize the piece of carrot rather 

 than the plug. On the 20th trial there was only a small piece 

 tied on the side of the plug but he refused to pull it. The fol- 

 lowing day he was again started with a small piece tied on the 

 plug but after opening the box eight times the piece was re- 

 moved and this time the animal seized the plug and pulled it 

 so hard that he strained the internal mechanism. After that 

 there was no more difiiculty. The lever which had been removed 

 was restored and the button and hook added in regular order, 

 so that in a few days No. 7 was as expert as other animals 

 had been and like the latter opened the box when placed on 

 the top of a table in the presence of several visitors. 



In comparing the habits of the porcupine in opening puzzle - 

 boxes with that of other animals used in that kind of experi- 



