The outstanding feature of the drift of population observed in our country of late is understood in terms of the population exodus from rural areas into urban or industrial areas, which brings about. a conspicuous decrease in rural population especially in that of the younger working age bracket. with a view to clarifying an aspect of such wide-ranging migration of population, a study was made in the three remote mountain villages in the Chilbu District, where people are living on an extremely low economic level Investigation conducted for eacch respective economic level revealed an even. abnormally advanced decrease in the population of such younger generation, far advanced than in average rural areas. Thus the unfavorable topogra-phical conditions, lack of cultivating lands, low income, etc.were considered to be responsible for the acceleration of such population exodus. Attention was also drawn to the fact that not only the surplus labor power but even many of the eldest sons. who are the successors to their fathers' occupations are turning to urban areas for employ-ment, threatening the possibility of the replenishment of agricultural labor power and the development of agricultural economics, as well as the future reproduction of population in rural areas.

Urinary mineral excretions were measured on five healthy 19-years-old female students in domestic sciences course of a woman's college and five healthy 18-19-years-old female students in physical training course, during the training camp of ski events.
The examination for the female students in domestic sciences course was done on 22 December as of ordinary time at school and on 23-25 December 1969 in training camp of ski event at a skiing ground. For the female students in physical training course the examination was done on 9-13 January 1970 in training camp at the same skiing ground and on 3-5 February 1970 in ordinary time at school. Every three hours urine was collected during the examination periods.
(1) Whole urine volume per 24 hours decreased in training camp in comparison with that in ordinary school time, while the excretion increased after the physical exercise and decreased during the sleeping hours.
(2) Creatinine excretion per 24 hours increased in the training camp and diurnally the excretion increased after the physical exercises. The variation of creatinine excretion seemed to be effected by the physical exercise.
(3) Decrease of Na excretion and increase of K excretion were observed in the students of domestic sciences course in training camp. Increase pattern of Na and K excretion with diurnal variation in training camp was observed with physical exercises.
(4) Urinary excretion of Ca and Mg increased by the female students of physical training course in training camp. On the diurnal pattern, the increase of Ca and Mg excretion caused by physical exercise showed some time lag of the peak compared to that of Na and K.
(5) Phosphorus excretion increased both in the students of domestic sciences course and of physical training course in training camp. The decrease of P excretion in the daytime and the increase in the sleeping hours was commonly observed for both groups.
(6) Following up the diurnal variations of urine volume and urinary excretions of Na, K, Ca and Mg in the female students of physical training course through the training camp for five days, difference between the increase of the excretions after, physical exercises and the decrease in sleeping hours got less day by day. Such a change seems to be the physiological adaptation of human body in order to control excess excretions of the important substances.
(7) Although the value of Na f K ratio fell in both student groups during training camp, the decrease was smaller for the physical training course group than for the domestic sciences course group. The fact that more excretions of urine volume and creatinine and less lowering of Na/K ratio than those of the domestic sciences course students were observed in the physical training course students seemed to be the effect of the daily training.