contentless elements of knowledge. These should be sharply distinguished from the indigenous, evoking, and more truly educational factors described in the last paragraph, which are meaty, content-full, and relatively formless as to time of day, method, spirit, and perhaps environment and personnel of teacher, and possibly somewhat in season of the year, almost as sharply as work differs from play, or perhaps as the virility of man that loves to command a phalanx, be a martinet and drill-master, differs from femininity which excels in persuasion, sympathetic insight, story-telling, and in the tact that discerns and utilizes spontaneous interests in the young. Adolescence is a new birth, for the higher and more completely human traits are now born. The qualities of body and soul that now emerge are far newer. The child comes from and harks back to a remoter past; the adolescent is neo-atavistic, and in him the later acquisitions of the race slowly become prepotent. Development is less gradual and more saltatory, suggestive of some ancient period of storm and stress when old moorings were broken and a higher level attained. The annual rate of growth in height, weight, and strength is increased and often doubled, and even more. Important functions, previously non-existent, arise. Growth of parts and organs loses its former proportions, some permanently and some for a season. Some of these are still growing in old age and others are soon arrested and atrophy. The old measures of dimensions become obsolete, and old harmonies are broken. The range of individual differences and average errors in all physical measurements and all psychic tests increases. Some linger long in the childish stage and advance late or slowly, while others push on with a sudden outburst of impulsion to early maturity. Bones and muscles lead all other tissues, as if they vied with each other; and there is frequent flabbiness or tension as one or the other leads. Nature arms youth for conflict with all the resources at her command--speed, power of shoulder, biceps, back, leg, jaw--strengthens and enlarges skull, thorax, hips, makes man aggressive and prepares woman's frame for maternity. * * * * * CHAPTER II THE MUSCLES AND MOTOR POWERS IN GENERAL Muscles as organs of the will, of character and even of thought--The muscular virtues--Fundamental and accessory muscles and functions--The development of the mind and of the upright position--Small muscles as organs of thought--School lays too much stress upon these--Chorea--vast numbers of automatic movements in children--Great variety of spontaneous activities--Poise, control and spurtiness--Pen and tongue wagging--Sedentary school life _vs_ free out-of-door activities--Modern decay of muscles, especially in girls--Plasticity of motor habits at puberty.