THE INTELLIGENCE OF MONKEYS. 275 



square at the right side of the front of the box. The door was at the 

 left side of the front. On Janviary 12th I put this box in No. 3's cage, 

 the door of the box being open. I put a bit of food in the box. No. 3 

 reached in and took it. This was repeated three times. I then put in a 

 bit of food and closed the door. No. 3 pulled and bit the box, turned it 

 over, fingered and bit at the hole where the lever was, but did not suc- 

 ceed in getting the door open. After ten minutes I took the box out. 

 The monkey having failed by his own impulsive efforts to depress the 

 lever, I began the tuition. I took No. 3 out and let him sit on my knees 

 (I sitting on the floor with the box in front of us). I would then put 

 my hand out toward the box and when he was looking at it would insert 

 my finger and depress the lever with as evident a movement as I could. 

 The door, of course, opened, and No. 3 put his arm in and took the bit 

 of food. I then put in another, closed the door and depressed the lever 

 as before. No. 3 watched my hand pretty constantly, as all his ex- 

 periences with me had made such watching profitable. After ten such 

 trials he was put back in the cage and the box put in with a large piece 

 of food in it and its door closed. No. 3 failed in the course of five 

 minutes to get the door open. His behavior was just the same as it had 

 been before he had seen me open the door ten times. He had not 

 profited at all by my example. Later I showed him 15 times more and 

 then tried him by himself. He failed as before. 



The two monkeys. No. 1 and No. 3, were given a number of such 

 chances to learn acts from seeing me. Other, boxes were used, the 

 doors of which could be opened by pulling up a bolt, pulling out a plug, 

 pushing a bar back into a slot, unwinding a wire and pulling a loop 

 off from a nail. I had also certain pieces of apparatus arranged which 

 Avould throw a bit of food down a chute into the cage when some 

 simple mechanisms were operated; when for instance a nail was pulled 

 out of a hole or a loop pulled off a nail or a bar pushed in. These could 

 be set up outside the cages so that the monkeys could reach them 

 through the wire netting and could easily see me operate them. 



No. 1 had in all eight chances to learn from seeing me. In seven 

 of the cases he failed utterly after seeing me operate the mechanisms 21, 

 5, 10, 4, 15, 40 and 15 times respectively. He did succeed in one case 

 where the act required was to pull a wire loop off a nail. This must, I 

 think, have been an accident. The other monkey failed utterly to learn 

 to do the same thing though he had continued tuition. 



No. 3 had seven chances to learn from seeing me. In five out of the 

 seven he failed after seeing me operate the mechanisms 40, 30, 25, 5 and 

 30 times respectively. In the case of the other two, although he suc- 

 ceeded in getting the door open, it was not by doing as I had shown 

 him. I opened a door 25 times by pulling a bolt up, but he opened it by 

 pulling and pushing at the door itself until he worked the bolt up out 



