A subtle but potent intersexual influence is among the strongest factors of all adolescent sport. Male birds and beasts show off their charms of beauty and accomplishment in many a liturgy of love antics in the presence of the female. This instinct seems somehow continuous with the growth of ornaments in the mating season. Song, tumbling, balking, mock fights, etc., are forms of animal courtship. The boy who turns cartwheels past the home of the girl of his fancy, is brilliant, brave, witty, erect, strong in her presence, and elsewhere dull and commonplace enough, illustrates the same principle. The true cake-walk as seen in the South is perhaps the purest expression of this impulse to courtship antics seen in man, but its irradiations are many and pervasive. The presence of the fair sex gives tonicity to youth's muscles and tension to his arteries to a degree of which he is rarely conscious. Defeat in all contests is more humiliating and victory more glorious thereby. Each sex is constantly passing the examination of the other, and each judges the other by standards different from its own. Alas for the young people who are not different with the other sex from what they are with their own!--and some are transformed into different beings. Achievement proclaims ability to support, defend, bring credit and even fame to the object of future choice, and no good point is lost. Physical force and skill, and above all, victory and glory, make a hero and invest him with a romantic glamour, which, even though concealed by conventionality or etiquette, is profoundly felt and makes the winner more or less irresistible. The applause of men and of mates is sweet and even intoxicating, but that of ladies is ravishing. By universal acclaim the fair belong to the brave, strong, and victorious. This stimulus is wholesome and refining. As is shown later, a bashful youth often selects a maiden onlooker and is sometimes quite unconsciously dominated in his every movement by a sense of her presence, stranger and apparently unnoticed though she be, although in the intellectual work of coeducation girls are most influenced thus. In athletics this motive makes for refinement and good form. The ideal knight, however fierce and terrible, must not be brutal, but show capacity for fine feeling, tenderness, magnanimity, and forbearance. Evolutionists tell us that woman has domesticated and educated savage man and taught him all his virtues by exercising her royal prerogative of selecting in her mate just those qualities that pleased her for transmission to future generations and eliminating others distasteful to her. If so, she is still engaged in this work as much as ever, and in his dull, slow way man feels that her presence enforces her standards, abhorrent though it would be to him to compromise in one iota his masculinity. Most plays and games in which both sexes participate have some of the advantages with some of the disadvantages of coeducation. Where both are partners rather than antagonists, there is less eviration. A gallant man would do his best to help, but his worst not to beat a lady. Thus, in general, the latter performs her best in her true rule of sympathetic spectator rather than as fellow player, and is now an important factor in the physical education of adolescents.