2. It follows from their instinctive character that animal plays are peculiar to the species which perform them. We find series of sports peculiar to dogs, others to cats, and so on through all the species of the zooelogical garden, whether the creatures be wild or tame. Each shows its species as clearly by its sportive habits as by its shape, cry, or any other of what are called its "specific" habits. This is important not only to the zooelogist, as indicating differences of evolution and scale of attainment, environment, etc., but also to the psychologist, as indicating differences of what we may call animal temperament. Animals show not only the individual differences which human beings do, one liking this game and another that, one being leader in the sport and another the follower, but also the greater differences which characterize races. The Spaniards love the bull fight; other nations consider it repulsive, and take their fun in less brutal forms, although, perchance, they tolerate Rugby football! So the animals vary in their tastes, some playing incessantly at fighting, and so zealously as to injure one another, while others like the milder romp, and the game with flying leaves, rolling stones, or the incoming waves on the shore. 3. Psychologically, the most interesting characteristic of animal, as of human, play is what is called the "make-believe" state of mind which enters into it. If we consider our own sports we find that, in the midst of the game, we are in a condition of divided consciousness. We indulge in the scheme of play, whatever it be, as if it were a real situation, at the same time preserving our sense that it is not real. That is, we distinguish through it all the actual realities, but make the convention with our companions that for the time we will act together as if the playful situation were real. With it there is a sense that it is a matter of voluntary indulgence that can stop at anytime; that the whole temporary illusion to which we submit is strictly our own doing, a job which we have "put up" on ourselves. That is what is meant by make-believe. Now it is clear that the animals have this sense of make-believe in their games both with other animals and with man. The dog plays at biting the hand of his master, and actually takes the member between his teeth and mumbles it; but all the while he stops short of painful pressure, and goes through a series of characteristic attitudes which show that he distinguishes very clearly between this play biting and the real. If perchance the master shows signs of being hurt, the dog falls into attitudes of sorrow, and apologizes fulsomely. So also when the animals play together, a vigorous squeal from a companion who is "under" generally brings him his release.