Gulick[1] has urged that what makes certain exercises more interesting than others is to be found in the phylon. The power to throw with accuracy and speed was once pivotal for survival, and non-throwers were eliminated. Those who could throw unusually well best overcame enemies, killed game, and sheltered family. The nervous and muscular systems are organized with certain definite tendencies and have back of them a racial setting. So running and dodging with speed and endurance, and hitting with a club, were also basal to hunting and fighting. Now that the need of these is leas urgent for utilitarian purposes, they are still necessary for perfecting the organism. This makes, for instance, baseball racially familiar, because it represents activities that were once and for a long time necessary for survival. We inherit tendencies of muscular coördination that have been of great racial utility. The best athletic sports and games a composed of these racially old elements, so that phylogenetic muscular history is of great importance. Why is it, this writer asks, that a city man so loves to sit all day and fish! It is because this interest dates back to time immemorial. We are the sons of fishermen, and early life was by the water's side, and this is our food supply. This explains why certain exercises are more interesting than others. It is because they touch and revive the deep basic emotions of the race. Thus we see that play is not doing things to be useful later, but it is rehearsing racial history. Plays and games change only in their external form, but the underlying neuro-muscular activities, and also the psychic content of them, are the same. Just as psychic states must be lived out up through the grades, so the physical activities most be played off, each in its own time.