Chimpanzees are not usually so playful or so funny as monkeys, but they have a certain degree of mirth in their nature, and at times display a marked sense of humor. Moses was fond of playing peek-a-boo. He did not try to conceal his body from view, but put his head behind a box or something to hide his eyes. Then he would cautiously peep at me. He would often put his head behind one of the large tin boxes in the cage, leaving his whole body visible. In this attitude he would utter a peculiar sound, then draw his head out and look to see if I were watching him. If not, he would repeat the act a few times and then resort to some other means of amusing himself. But if he could gain attention the romp began. He found great pleasure in this simple pastime. He would roll over, kick up his heels, and grin with evident delight. His favorite hour for this sport was in the early part of the afternoon. I spent much time in entertaining him in this way and in many others, feeling amply repaid by the gratification it afforded him. I could not resist his overtures to play, as he was my only companion; and, living in that solitary manner, we found mutual pleasure in such diversions. Another occasion on which he used to peep at me was when he lay down to take his midday nap. For this I had made him a little hammock. It was suspended by wires hooked in the top of my cage, so as to be removable when not in use. I always hung this near me, so I could swing him to sleep like a child. He liked this very much, and I liked equally well to indulge him in it. When he was laid in this little hammock, he was usually covered up with a small piece of canvas, and in spreading it over him I sometimes laid the edge of it over his eyes. But this caused him to suspect me of having some motive in doing so. Then he would reach his finger up, catch the edge of the cloth and gently draw it down, so as to see what I was doing. If he found that he was detected, he quickly released the cloth, and cuddled down as though he had drawn it down by accident; but the little rogue knew just as well as I did that it was not fair to peep.