It is also a period of the greatest interest to the mother, provided there is sympathy, confidence and understanding between them. Too much importance cannot be attached to the necessity of an early confidence between the girl and her mother before this period arrives for this will give a girl a sense of superiority, a poise, an understanding of herself and her nature. She will then be prepared for the changes taking place within herself, and consequently be practically immune from the influence of a bad environment, which otherwise might affect her in a way detrimental to her health and happiness. Up to this period there is very little manifestation of sex. Fortunately, we have come to recognize that healthy outdoor play is as good for the little girl as it is for the boy, and the ideas of our grandmothers' day—that boys were to play ball, ride horseback, swim, shoot, etc., while the girl's play was restricted to sedentary pursuits, such as sewing, doll playing, etc.—have been placed on the relic heap, and the girl of today keeps pace with her brother in physical freedom and activity. With the passing of those ideas passed also our ideal of the delicate girl, with a cough, small waist and dainty appetite, and the girl physically strong and healthy, with a broader view of life, has taken her place. About the age of 12 there comes a sudden change in the girl, her dresses are outgrown, her form assumes shape, her bust and limbs develop, and, in the words of Stanley Hall, “hips, thighs, limbs, shoulders and arms round out into contours more or less beautiful, curves always predominating over angles.” Thus we come to realize that the little girl has left us. The physical development is not alone in this work, for the mental and moral instincts are developing so rapidly that it is difficult to understand this new and lovely creature who is neither the child of yesterday nor the woman of tomorrow. There is often very little patience shown the adolescent girl, for neither parents nor teachers have been aware that this is a separate and distinct stage—this passing from childhood into womanhood—and as such must be recognized. Let us first take the bony structure. It is a well known fact that there is not sufficient lime salts in the system to complete the bony structure until the 25th year. The bones are not completely hardened, which is one of the reasons that so many deformities have their foundation laid at this time. The first and most noticeable change in the girl at this age is the increase of height, which begins at the 13th year and ends about the 15th. There are girls who begin earlier and continue to grow for several years after this age, but it is with the average we deal, and the growth after the age of 15 is not so perceptible.