In studying the mental status of the primates I attach great importance to the work and results of the professional trainers who educate animals for stage performances. If the trainer does not know which are the brightest species of apes, baboons and monkeys, then who does? Their own fortunes depend upon their estimate of comparative mentality in the primates. Fortunately for our purposes, the minds of the most intelligent and capable apes, baboons, and monkeys have been partially developed and exploited by stage trainers, and to a far less extent by keepers in zoological parks. Some wonderful results have been achieved, and the best of these have been seen by the public in theatres, in traveling shows and in zoological parks. All these performances have greatly interested me, because they go so far as measures of mental capacity. I wish to make it clear that I take them very seriously. [Illustration with caption: PORTRAIT OF A HIGH-CASTE CHIMPANZEE "Baldy" was an animal of fine intelligence and originality in thought. He was a natural comedian] While many of the acts of trained animals are due to their power of mimicry and are produced by imitation rather than by original thought, even their imitative work reveals a breadth of intelligence, a range of memory and of activity and precision in thought and in energy which no logical mind can ignore. To say that a chimpanzee who can swing through thirty or forty different acts "does not think" and "does not reason," is to deny the evidence of the human senses, and fall outside the bounds of human reason. Training Apes for Performances. As will appear in its own chapter, there is nothing at all mysterious in the training of apes. The subject must be young, and pliant in mind, and of cheerful and kind disposition. The poor subjects are left for cage life. The trainer must possess intelligence of good quality, infinite patience and tireless industry. Furthermore, the stage properties must be ample. An outfit of this kind can train any ape that is mentally and physically a good subject. Of course in every animal species, wild or domestic, there are individuals so dull and stupid that it is inexpedient to try to educate them. The chimpanzee Suzette who came to us direct from the vaudeville stage performed every summer in her open-air "arena cage," until she entered motherhood, which put an end to her stage work. She was a brilliant "trick" bicycle rider. She could stand upright on a huge wooden ball, and by expert balancing and foot-work roll it up a steep incline, down a flight of stairs, and land it safely upon the stage, without once losing her balance or her control. She was entirely at home on roller skates, and when taken out upon the pavement of Baird Court she would go wildly careering around the large grass plat at high speed.