DRYPTOSAURUS. THE PREHISTORIC ANIMALS, TOO, UNDOUBTEDLY HAD THEIR PLAY TIME, WITH GAMES AND "SETTING UP" EXERCISES.] [Illustration: _American Museum of Natural History, New York_ A HAPPY FAMILY OF POLAR BEARS. THE YOUNG CUBS WRESTLE AND TUMBLE, AS PLAYFULLY AS TWO PUPPIES. THIS PLAY HAS MUCH TO DO WITH THEIR PHYSICAL AND MENTAL DEVELOPMENT.] Many scientists have claimed that this so-called instinct should not be classed as real play. However, such an authority as Darwin thought it was play, and Scheitlin said that the cat let the mouse loose many times in order that she might have the experience of catching it each time. No mercy is shown the helpless mouse, which is the same to her as the toy ball--in the same way as a real beetle and a toy beetle are the same to a small child. Evidently the cat does not play with the mouse for the delight in torturing it, but purely for practice that she may become skilled in the art of catching it. The cat also exercises in springing movements, and by studying the mouse's probable movements, learns to acquire a knowledge and skill in mouse-ways otherwise impossible. The same cruel practice is found among leopards, panthers, and wild cats. Brehm verifies the observation that many members of the cat family practise torturing their victims in a horrible manner, pretending to liberate them, until the poor creatures at last die from their wounds. Lenz tells of a marten that would play with its prey for hours when not hungry. Especially was this true when marmots chanced to be his victims, and around these he would leap and spring, dealing them terrific blows first with one paw and then with the other. When hungry, however, he proceeded differently, devouring them at once from teeth to tail. All the cat family, it seems, are fond of human companionship, and take almost as much delight in playing with human beings as with their own kind. This is especially true of the puma. Brehm tells of a tame one that delighted in hiding at the approach of his master and springing out unexpectedly, just as the lion does. Hudson claimed that the puma, with the exception of the monkey, was possibly the most playful of all animals. Travellers tell many interesting tales of the play of these animals, especially on the Pampas of South America. Gross relates the experience of an Englishman who was compelled to spend the night outdoors on the Pampas of the La Plata. At about nine o'clock, on a bright moonlight night, he saw four pumas coming toward him, two adult animals and two young ones. He well knew that these animals would not attack him, so he quietly waited. In a short time they approached him, chasing one another and playing hide-and-seek like little kittens; and finally leaped directly over the man several times. The mother cat would run ahead, calling to the little ones to follow her. But she never disturbed him.