THE HUMAN SIDE OF APES
approach to deliberate and formal reasoning; yet her mental adjustments to complex and varying situations were far beyond the capacity of the lower mammals. For life in a tropical forest, where she had to be ever watchful, active, and resourceful, she was an admirably adapted piece of animal mechanism, but her attempts to solve problems requiring deliberation or reflection showed that she was not equal to such tasks. When an apple was placed on a small piece of board outside her cage, she first tried to reach the apple directly, but failing in this she seized the edge of the board and with some difficulty drew it toward her and obtained the prize. When I drove a nail in the board to serve as a sort of handle she reached directly for the nail, drew in the board, and seized the apple. I then substituted a longer board, on which the apple was too far out to be reached even when the near end was pulled against the cage. Lizzie then first pulled the board in by the nail, then drew it sidewise until the apple was sufficiently near to be seized. The appropriate acts were done at the first trial, apparently as a result of inspecting the situation and judging what must be done to get the food. When an apple was placed not on the board but near it, Lizzie drew the board in repeatedly and seemed disappointed because the apple did not come also. She could clearly see that the apple was not on the board, but she did not perceive the futility of her usual performance. When given a nut inside a Mason jar, with the cover screwed on, she would bite and work at the cover, turning it this way and that until it finally came loose. Even after making numerous trials she never learned that the top could be unscrewed by continuously turning it in one direction. When food was placed in a box having a lid fastened by a button or a hook, she could open the box only by working at the fastenings with her hands and teeth until the lid
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