third period, continuing to the end of November, in which the increase in height is very small and the gain in weight verylarge. The daily accession of weight is often three times as great as during the winter months; and an earlier beginning of the summer vacation will be accompanied by a stronger growth in weight during the holiday time. These facts are of great moment in aiding to determine the best arrangement of vacations—an important question in school management.
From this discussion of the different phases in their growth I pass to the diseases of our school children. First, according to my examinations of fifteen thousand boys in the middle schools, more than one third are ill or are afflicted with chronic maladies. Short-sightedness, which is demonstrably for the most part induced by the overtaxing of the eyes in school-work, and well merits the name of school-sickness, rises rapidly in height of prevalence from class to class. Thirteen and a half per cent of the boys suffer from habitual headache, and nearly thirteen per cent are pallid; and other diseases arise in the lower classes and then decline to rise again in the upper classes. Diseases of the lungs are most frequent among organic disorders. Diseases of the heart and intestinal disorders show a considerable tendency to increase in the higher classes. As to the average of illness in the different classes, it appears that in Stockholm seventeen per cent of the children in the first class were ill at the end of the first school year. In the second school year the illness-curve rose to thirty-seven per cent, and in the fourth class to forty per cent. This remarkable increase of illness during the first school year is not casual, but is exhibited in all the schools; and corresponding conditions were brought to light in the examinations of Danish pupils. A sickness ratio of 34·4 per cent was found as early as in the lowest classes of the middle schools. The illness-curve rose in the first classes, reached its first maximum in the third class, then sunk and rose again in the upper classes. These wavering conditions can not be founded in the organization of the school. The burden of work on the pupil rises incessantly from class to class, and the boys live continuously under the same hygienic conditions in the same places, and in the same school and parental houses. There must be a deeper underlying cause. A look at the growth-periods of the boys shows that the remarkable rise of the sickness-curve in the preparatory schools and the lower classes of the middle schools occurs exactly during the period from seven or eight years to thirteen years, the very time that has been shown to be one of weaker growth in boys. But as soon as the stronger growth of puberty sets in, and especially during the last years of that period, when the gain in weight is most rapid, the curve sinks from class to class, from year to year, till the year in which the
