70 ROBERT M. YERKES 



what at the time seemed a rather startHng condition, but rapidly 

 regained his usual good health, and on June 3, although some- 

 what weak and listless, he again worked fairly steadily. 



Since it was now possible to lock the doors and confine the 

 animal for any desired period, on June 5 the interval of punish- 

 ment was made sixty seconds, and a liberal quantity of banana, 

 beet, or carrot was offered as reward. No increase in the num- 

 ber of successful choices appeared, and Julius showed discourage- 

 ment. Sawdust had been strewn on the floor, and in the inter- 

 vals between trials as well as during confinement in wTong boxes, 

 he took to playing with the sawdust. He would take it up in 

 one hand and pour it from hand to hand until all had slipped 

 through his fingers, then he would scrape together another 

 handful and go through the same process. Often he became 

 so intent on this form of amusement that even when the exit 

 door was raised, he would not immediately go to get the food. 



The reactive tendencies which appeared in the work on prob- 

 lem 2 will now be presented in order, since I shall have to refer 

 to them repeatedly, and the list will be more useful to the reader 

 at this point than at the conclusion of the presentation of daily 

 results. The following is not an exhaustive list but includes 

 only the most important and conspicuous tendencies or methods 

 together with the dates on which they were most apparent. 



(a) May 17, choice of first box at left of group or near it, then 

 the next in order, and so on, until the second from the right was 

 reached. This method with irregularities and certain definite 

 skipping was used at various times, sometimes over periods of 

 several days, during the course of the work. 



(b) June 3, preference for number 3 and number 4 developed 

 immediately after the orang utan's illness and when he was work- 

 ing rather listlessly. 



On June 9 and 10, the original tendency (a) reappeared and 

 persisted for a number of series. 



(c) June 14, a tendency to choose the box at or near the right 

 end of a group, and then the one next to it. In connection 

 with this tendency, which of course required only two choices 

 in any given trial, interest in playing with the sawdust on the 

 floor developed. 



Again on June 21, the animal returned to the use of tendencv 

 (a). 



