Playful bears are much given to playing tricks, and teasing each other. A bear sleeping out in the open den is regarded as a proper subject for hectoring, by a sudden bite or cuff, or a general assault. It is natural to expect that wrestling bears will frequently become angry and fight; but such is not the case. This often happens with boys and men, but bears play the game consistently to the end. I can not recall a single instance of a real bear fight as the result of a wrestling or boxing match; and may all boys take note of this good example from the bear dens. Next to the bears, the apes and monkeys are our most playful animals. Here, also, it is the young and the half grown members of the company that are most active in play. Fully mature animals are too sedate, or too heavy, for the frivolities of youth. A well- matched pair of young chimpanzees will wrestle and play longer and harder than the young of any other primate species known to me. It is important to cage together only young apes of equal size and strength, for if there is any marked disparity in size, the larger and stronger animal will wear out the strength of its smaller cage-mate, and impair its health. In playing, young chimps, orangs or monkeys seize each other and wrestle, fall, and roll over and over, indefinitely. They make great pretenses of biting each other, but it is all make-believe. My favorite orang-utan pet in Borneo loved to play at biting me, but whenever the pressure became too strong I would say chidingly, "Ah! Ah!" and his jaws would instantly relax. He loved to butt me in the chest with his head, make wry faces, and make funny noises with his lips. I tried to teach him "cat's cradle" but it was too much for him. His clumsy fingers could not manage it. One of our brightest chimpanzees, named Baldy, was much given to hectoring his female cage-mate, for sport. What he regarded as his best joke was destroying her bed. Many times over, after she had laboriously carried straw up to the balcony, carefully made up a nice, soft, circular bed for herself, and settled down upon it for a well-earned rest, Baldy would silently climb up to her level, suddenly fling himself upon her as she lay, and with all four of his arms and legs violently working, the nest would be torn to pieces and scattered and the lady orang rudely pulled about. Then Baldy would joyously swing down to the lower level, settle himself demurely at the front of the cage, and with a placid face and innocent, far-away expression in his eyes gaze at the crowd. There was nothing lacking but a mischievous wink of one eye. Whenever his cage-mate selected a particularly long and perfect straw and placed it crosswise in her mouth, Baldy would steal up behind her and gleefully snatch it away.