In the fall of 1891, I visited New York for the purpose of experimenting with the monkeys in Central Park. Early one morning I repaired to the monkey-house, and for the first time approached a cage containing five brown Capuchins, whom I saluted with the word which I have translated "food," and which seems to be an "open-sesame" to the hearts of all monkeys of this species. On delivering this word, one of them responded promptly and came to the front of the cage. I repeated it two or three times and the remaining four came to the front, and as I thrust my fingers through the bars of the cage, they took hold of them and began playing with great familiarity and apparent pleasure. They seemed to recognise the sound, and to realise that it had been delivered to them by myself. Whether they regarded me as a great ape, monkey, or some other kind of animal speaking their tongue, I do not know. But they evidently understood the sound, though up to this time I had shown them no food or water. A little later I secured some apples and carrots, and gave them in small bits in response to their continual requests for food, and this further confirmed my belief that I had translated the word correctly. This was gratifying to me in view of the fact that I was accompanied by two gentlemen who had been permitted to witness the experiment, and it was evident to them that the monkeys understood the sound. I placed the phonograph in order and made a record of the sound, which I preserved for study. After an absence of some days, I returned to the Park and went to the monkey-house. They recognised me as I entered the door, notwithstanding there were many visitors present. They began begging me to come to their cage, which I did, and gave them my hand to play with. One of them in particular, whose name is "McGinty," showed every sign of pleasure at my visit; he would play with my fingers, hug them, and caress them in the most affectionate manner. Another occupant of the same cage had shown a disposition to become friendly with me, and on this occasion came bravely to the bars of the cage and showed a desire to share the pleasure of my visit with his little Simian brother. But this was denied him on any terms by "McGinty," who pounced upon him and drove him away, as he also did the other monkeys in the cage in order to monopolise my entire society himself. He refused to allow any other inmate of the cage to receive my caresses or any part of the food that I had brought them. I spent the past winter in Washington and New York, much of the time in company with these little creatures, and have made many novel and curious experiments, some of which have resulted in surprises to myself. [Sidenote: MONKEYS CAN COUNT] Among the facts which I have obtained, I may state that certain monkeys can count three; that they discern values by quantity and by number; that they have favourite colours, and are pleased with some musical sounds. And I shall explain how I arrived at