I have never regarded the training of animals as the true measure of their mental powers. The real test is to reduce the animal to his own resources, and see how he will conduct himself under conditions that present new problems. Animals may be taught to do many things in a mechanical way, and without any motive that relates to the action; but when they can work out the solution without the aid of man, it is only the faculty of reason that can guide them. One thing that Aaron could never figure out was--what became of the chimpanzee that he saw in a mirror. I have seen him hunt for that mysterious ape an hour at a time. He once broke a piece off a mirror I had in trying to find the other fellow, but he never succeeded. I have held the glass firmly before him, while he put his face up close to it--sometimes almost in contact. He would quietly gaze at the image and then reach his hand around the glass to feel for it. Not finding it, he would peep around the side of the glass and then look into it again. He would take hold of it and turn it around, lay it on the ground, look at the image again, and put his hand under the edge of the glass. The look of inquiry in that quaint face was so striking as to make one pity him. But he was hard to discourage. He resumed the search whenever he had the mirror. Elisheba never worried herself much about it. When she saw the image in the glass she seemed to recognize it as one of her kind; but when it vanished she let it go without trying to find it. In fact, she often turned away from it as though she did not admire it. She rarely ever took hold of the glass, and she never felt behind it for the other ape. Altogether Elisheba was an odd specimen of her tribe--eccentric and whimsical beyond anything I have ever known among animals; yet, with all her freaks, Aaron was fond of her and she afforded him company; but he was extremely jealous of her, and permitted no stranger to take any liberties with her with impunity. He did not object to their doing so with him. He rarely took offense at any degree of familiarity, for he would make friends with any one who was gentle with him; but he could not tolerate their attentions to her. She betrayed no sign of affection for him except when some one annoyed or vexed him; but in that event she never failed to take his part against all odds. At such times she became frantic with rage, and if the cause was prolonged, she often for hours afterwards refused to eat. On the voyage homeward there was on board another chimpanzee, belonging to a sailor who was bringing him home for sale. This one was about two years older than Aaron and fully twice as large. He was tame and gentle, but was kept in a close cage by himself. He saw the others roaming about the deck and tried to make up with them; but they evinced no desire to become intimate with one who was confined in such a manner.