Page:Popular Science Monthly Volume 34.djvu/88

78 each of the three years the greatest increase in weight took place in the fall until the beginning of winter, then till the end of April the increase grew less, and after this time a loss in weight was noticed. At times the increase in weight of the children would cease suddenly for a few days, and occasionally during the time when an increase was expected a general decrease occurred. Based upon his measurements and annotations, Malling-Hansen framed the following rule: The weight of a boy ranging from the age of nine to fifteen undergoes three periods annually—a maximum, a medium, and a minimum period. The maximum period lasts four and a half months, commencing in August and ending the middle of December; the medium stage has the same duration, from the middle of December to the end of April. The minimum period appears during the remaining three months, from the end of April to the end of July. The increase in weight during the maximum period is three times that of the medium period, and almost all the gain of the medium period is again lost during the minimum period. From the working of this law it follows that in changing the diet at academies, schools, and asylums, the season should be considered. A good diet would give less satisfactory results if observed from April to June, than a poorer diet if noted from August until December.

In the same manner as the increase in weight, the increase of growth fluctuates, and can likewise be divided into three periods. These periods commence and close about a fortnight before the periods of weight, but in such a manner that the minimum period of growth occurs at the time when the weight remains stationary, and may at times even be coincident with important loss in weight. Growth takes place, one might say, at the expense of the increase of weight. Accurate observation showed that the general growth of the trees in the garden of the institution corresponded essentially with the growth of the children. The maximum period of growth upward is followed by that of increase in circumference. The growth of the human body and the growth of the trees are consequently influenced in the same manner by some disposing cause. But what is this cause?

As the fluctuations referred to above coincided strikingly with the fluctuations of atmospheric warmth, Malling-Hansen believed that they could be attributed to local meteorological conditions; and it was really shown that with a rise of temperature the weight increased, and vice versa. It was, however, ascertained that during the minimum period a rapid rise of temperature but slightly affected the increase in weight, and in the same way the decrease in temperature during the maximum period influenced the weight but little.

Furthermore, it seemed remarkable that the children should