414 'Journal of Comparative Neurology and Psychology. 



quite excited. Probably her increased activity served as au increased stimu- 

 lation to No. 2, for after her removal he gave more continuous attention to 

 the door, and then went from the door to the plug and pulled. He repeatedly 

 tried the plug and finally succeeded in pulling it out. After his first success, 

 however, he did not go to the door, although he did after the next. The 

 one experience, however, did not establish a perfect act, for when the device 

 was reset he did not go at once to the plug, but worked at the door instead. 

 ITe gave up trying to get the food and went about the cage. He went to 

 the plug again only when his eyes accidentally (so it seemed) fell upon it. 

 In the third experience there was apparent an element of accident, but 

 after he got food the third time, he seemed to know the tricli perfectly. 



D. Behavior of No. 6. 



Preliminary trials. — First trial. No. 6 climbed the cage and then went to 

 the door and pushed at it. He examined all about it and then climbed the 

 wire. He grasped the plug three times. Then he went back to the door six 

 times and pushed it. Later he bit the i^lug. 



Second trial. No. 6 was very playful. He leaped about the floor and up 

 the wire. Once he went to the food door and later he went to the plug and 

 bit it. He then went back to the floor and to the food door. He pushed 

 at it and then played about the cage. 



Third trial. No. 6 showed no interest in either the door or the i)lug. 



Fourth trial. On the fourth day No. 6 was very active. He looked at 

 the door and later perched at the plug, but he made no effort to pull it out. 



Fifth trial. On the fiftli day No. 6 went to the door and looked at the 

 food. Then he ran about the cage. He was totally indifferent to the plug, 

 and although he had been eager to get into the cage he was eager to leave 

 it at the end of the period. 



Imitation tests. — No. 6 imitating No. 5. — The two animals were in the cage 

 together in each of the following tests. 



First test. No. 6 soon discovered the food outside of the glass door and 

 when No. 5 opened it No. 6 got the food. No. 5 punished him several times 

 and No. 6 cried so much that his howling compelled liis removal. 



Second test. No. 6 was in the cage with No. 5 while she opened the door 

 twenty times. He rarely saw — not more than five times in the twenty. No. 

 6 learned that the door opened and was inclined to sit in front of it. This 

 turned his back to the iilug and he did not see No. 5 pull it. Finally No. 

 5 drove him away from the door and he saw her pull the plug a few times. 



When No. 5 was removed No. 6 went to the door and examined it. Then 

 he ran up to the plug, bit at the end of it, and tried to pull it out. He ran 

 down to the door at once. He climbed to the plug and worked at it with 

 his hands. Several times he repeated this trip from the plug to the door 

 and back to the plug. 



Third test. No. 5 was very eager to get the food. No. 6 saw only occa- 

 sionally — five times in fifteen. 



When No. 5 was removed No. 6 gave his first attention to the door. Then 

 lie climbed to the plug, but did not work at it. He worked persistently at 



