Finding it on this testimony not incredible that a bird could count as far as five, I thought it worth while to try what might be done with a more intelligent animal in this connection. Accordingly, about a year ago, I began, with the assistance of the keeper, to instruct the chimpanzee at the Zoological Gardens in the art of computation. The method adopted was to ask her for one, two, three, four, or five straws, which she was to pick up and hand out from among the litter in her cage. Of course, no constant order was observed in making these requests, but whenever she handed a number not asked for her offer was refused. In this way the animal learnt to associate the numbers with their names. Lastly, if more than one straw were asked for she was taught to hold the others in her mouth until the required number was complete, and then to deliver the whole at once. This method prevented any possible error arising from her interpretation of vocal tones, an error which might well have arisen if each straw had been asked for separately. After a few weeks' continuous instruction the ape perfectly well understood what was required of her, and up to the time when I left town, several months ago, she rarely made a mistake in handing me the exact number of straws that I named. Doubtless she still continues to do so for her keeper. For instance, if she is asked for four straws she successively picks up three and puts them in her mouth, then she picks up a fourth and hands over all the four together. Thus, there can be no doubt that the animal is clearly able to distinguish between the numbers 1, 2, 3, 4, and 5, and that she understands the name for each. But as this chimpanzee is somewhat capricious in her moods, even private visitors must not be disappointed if they fail to be entertained by an exhibition of her learning, a caution which it seems desirable to add, as this is the first time that the attainments of my pupil have been made known to the public, although they have been witnessed by officers of the Society and other biological friends.