406 "Journal of Comparative Neurology and Psychology. 



First test. It was the first time No. 2 and No. 4 were togetlier. Tliey 

 caressed at ouce and then No. 4 went to the screen. She lifted it five times 

 and got food each time. No. 2 sat by her and seemed to see every movement, 

 although his excitement may have kept his attention from centering on what 

 she was doing. When No. 4 was removed No. 2 displayed no more than 

 usual interest in the screen. He climbed to it, picked at it with his fingers and 

 used it as a stand to climb up the post. 



Second test. No. 2 was excited and was attentive to No. 4. He ate the 

 apple crumbs which she dropped after the first opening. At the second and 

 fifth opening he was ''pidcing fleas," and did not see the screen go up. 



While she was eating her fifth feed he went to the screen and examined it. 

 The sixth and seventh times she lifted it, he saw perfectly. After the 

 seventh he went to the screen and pushed against the lower edge of the 

 frame and then bit at it where it joined the cage post. 



After No. 4 had been taken out No. 2 began to work at the screen. He 

 picked at the lower edge of the frame where it joined the post and then 

 climbed upon the screen. He was too excited to work persistently, running 

 to the side of the cage and starting at every noise. He worked intermittently 

 for six minutes. Then when at the opposite side of the cage he started, ran 

 to the screen and gave a single push upward on the lower edge of the 

 frame. He then put both hands on the frame, but did not push. Because of 

 his activity the period was prolonged to fifteen minutes. 



Third test. No. 2 saw No. 4 the first time she got food and climbed the 

 cage to get food from her. He saw the second time and got food from the 

 hole while the screen stuck. When his food was gone No. 2 went to the 

 screen and pulled at the top and pushed at the lower edge. He saw the 

 third time, but became interested in picking fleas from No. 4 instead of 

 getting food. The fourth and fifth times he saw perfectly. 



After No. 4 had been taken out No. 2 ran about the cage, but paid no 

 attention to the screen for the first four minutes. Then he worked at the 

 lower edge of the screen a little. 



Fourth test. After the third performance No. 2 went to the screen and 

 touched it. After the fourth he went to it, put his hands against it and 

 pushed, but he failed to lift it. Each of the five times he saw very well. 



After No. 4 had been removed No. 2 went to the screen a number of times 

 and put his hands on it. He also bit the lower part of the frame and climbed 

 upon the screen. 



Fifth test. No. 2 saw No. 4 well each time. He went to the screen after 

 No. 4 had opened it and remained there while No. 4 ate her food. His 

 efforts to get food were feeble. 



After No. 4 had been taken out No. 2 climbed up on the screen a number 

 of times, but in no case did he seem bent on getting the food. 



Sixth test. No. 2 was interested in No. 4 and saw her get food each time 

 in twenty. A few times he put his hands on the screen. 



After No. 4 had been taken out No. 2 moved about the cage and worked 

 but slightly at the screen. 



