354: KANSAS ACADEMY OF SCIENCE. 



late mental growth at the expense of physical ; hence great danger 

 arises to both body and mental health. 



If we should desire correct statistics with regard to the health and 

 physical development of school children, they must include a large 

 number of them. Investigations of this character have been made in 

 several foreign countries. A fundamental research was made in 

 Copenhagen, giving results so significant that a special hygenic com- 

 mission was appointed in all the schools of that country. 



The commission did examine nearly 18,000 children — 15,000 boys 

 and 3000 girls. The boys came from the middle to the preparatory 

 schools, and the girls from private schools. Cognizance was taken of 

 their health, and they were measured and weighed. The commission 

 found by this research that the boys pass through three separate and 

 distinct periods of growth. In their seventh and eighth years there 

 was a moderate increase; from their ninth to thirteenth years a 

 weaker growth, and from fourteen to sixteen years, or during the 

 period of puberty, a much more rapid increase. The girls in their 

 development also presented three separate and distinct periods, but 

 the changes occurred a few years earlier. It was found that well-to-do 

 classes began to develop a year earlier ; that the scanty and hard con- 

 ditions of life retarded this growth. It was also found that while this 

 development of puberty was delayed in the poorer classes, when it 

 began it went on with increased rapidity, and its completion was in 

 the same years of their much more favored companions. 



A suggestive question, or at least one of vast moment in relation 

 to education, confronts us at this time. Is this growth evenly made 

 during the different seasons of the year ? We find by close research 

 that there is a light growth from November 30 to March 31. This 

 period is followed by a term from March 31 until August 31 that 

 shows rapid growth in height, and a small increase in weight. We 

 pass now to the third period, which extends to the end of November, 

 in which the increase in height is small, but the gain in weight is 

 large ; sometimes this gain daily is three times as great as during the 

 winter months. 



This commission found among the schoolboys a greater per cent, 

 of illness during the period of weak growth, which precedes the com- 

 ing of puberty, and during their passage through the preparatory 

 classes of the schools they found the percentage of illness among the 

 girls much greater than among the boys. Nearly sixty-one per cent, 

 of the girls, all of whom belong to the better class, were ill or afflicted 

 with serious chronic disorders. Such a condition of affairs, growing 

 worse in the years preceding puberty and during its beginning, cer- 

 tainly deserves careful attention. Professor Key, of Stockholm, com- 



