MENTAL LIFE OF MONKEYS AND APES 111 



rate, Skirrl's behavior was significant in this connection, for 

 he would pick up the hose to see if water were flowing, and if 

 it were not, he would throw it down, go directly to the faucet, 

 and try to turn the wheel. The association of the wheel with 

 the desired flow of water was therefore definitely established. 

 Shall we describe the act as ideational? It seems the natural 

 thing to do. 



3. Sobke, Pithecus rhesus 

 Box Stacking Experiment 



For this test, in the case of Sobke, three light boxes made 

 of redwood about one-third of an inch thick were used. The 

 smallest, box 1, was six inches in each direction, the next larger, 

 box 2, was twelve inches, and the third, box 3, eighteen inches. 

 As in the case of the other animals, bait, either banana or carrot, 

 was suspended from the middle of the roof of the large cage 

 at such distance from the floor as to be reached by the animal 

 only by the use of the boxes. 



The first observations on Sobke were made on June 14. The 

 three boxes had been placed in the form of a pyramid directly 

 under the banana, which hung about eighteen inches above the 

 uppermost box. Sobke' s attention while in his cage had been 

 attracted to the bait by seeing me fastening it in position, but 

 when admitted to the large cage, he simply glanced at it and 

 then wandered about the cage, picking up bits of food and 

 struggling to get at the other monkeys. This he did for about 

 five minutes. He then went to the boxes, placed his hands 

 on top of the bottom one, but did not climb up on it. A few 

 minutes later he returned to the box again, climbed up, and 

 readily reached the food, which he ate while resting on boxes 

 1 and 2. 



I now replaced the bait and gave the monkey a second chance 

 to obtain it. Almost immediately he climbed up as far as the 

 second box, but although he could reach the banana only from 

 the uppermost box, he deliberately shoved it off to the ground 

 and sat down upon box 2. As he was unable to obtain the 

 banana from this, he soon began to gnaw and pull at it, and as 

 he was succeeding all too well in his efforts to tear the box to 

 pieces, he had to be returned to his cage. 



The most important features of his behavior were, first, his 



