The Speech of Monkeys

In my efforts to ascertain their mathematical skill, I would take in one hand a little platter containing one nut, or one small bit of something to eat, such as a piece of apple or carrot cut into a small cube. In the other hand I held a small platter, with two or three such articles of the same size and colour, and holding them just out of reach of the monkey and changing them from hand to hand, I observed that the monkey would try to reach the one containing the greater number. He readily discerned which platter contained one and which contained two or three pieces. I was long in doubt whether he distinguished by number or by quantity, and my belief was that it was by quantity only. I first determined that he could tell singular from plural, by making the one piece larger and sometimes of a different shape, and from his choice of these I quite satisfied my own mind that he could distinguish by number. [Sidenote: THE TEST WITH MARBLES] I next set out to find how far in numerals his acquirements reached, and after a great number of indecisive trials I fell upon this simple plan: I took a little square wooden box and made a hole in one side just large enough for the monkey to withdraw his hand with a marble in it.