The author alleges the connection of physiologic pecularities of age and periodicity of human functions during a school year. He points out the factors of a good development of school and after-school work of pupils, a right organization, eating, sleeping, stay in the open air.
The author did a research of 4>uplls* letters of apologies in 1956—60. This research bears out opinions of many hygienists. A rising tendency of absences from the first till 11th classes has been ascertained.
Besides hygienic causes, in the number of absences there participated moral character couses, subjective relation of the pupil towards school, didactical, social, family causes.
On the basis of his research the author is inclined to believe the idea of dividing the school year in trimesters with 14 days of holidays in the second part of December and March. There are added schemes containing the amplitudes of absences during a school year.