The growing youth needs extra protein food for the building of protoplasm and a sufficiency of salts for the rapidly-forming tissues; earthy salts for bones, iron for blood, phosphorus for nervous tissue and its general influence on growth, obtained from the average liberal mixed diet with milk, eggs, fresh fruit and green vegetables, so that no special plan of feeding is required. If the adolescent lead a very active existence, equivalent to hard labor in an adult, he will naturally require the same amount of food with necessary reduction for weight, and some allowance for extra protein. Many adolescents, however, are very sluggish and lead inactive lives, and need encouragement to activity, with food in proportion to its degree. Again the appetite is not always a safe guide, especially for girls; for the period of adolescence coincides with the development of "hysterical" tendencies which may be manifested by excessive or diminished craving for food without any reference to the actual physical demands. An active adolescent may have but little appetite while a sluggish one may be a glutton, or may continually drink water. The perverted cravings for substances of no nutritive value and without appetizing quality, which accompany this period, are well known. It is therefore necessary that the diet of this period be as carefully supervised as that for the little child. The food must conform to the subject's physical requirements, and must be administered with discretion, for a large percentage of food aversions are acquired at this time, and it is essential to the well-being of the individual, and the comfort of others, that his eating habits be normal.