with, all its variations and fluctuations, stands in close relation to the sum-total of heat of the earth's atmosphere.
As, however, the warmth of the sun is influenced differently at different places by clouds, by wind, and by dampness, it never reaches the organisms in its original condition. Notwithstanding this, however, the fluctuations of weight-increase progress in harmony. Whatever it is that thus influences growth comes to us with the speed of the sun's rays; it varies from day to day, its intensity is the same at the same time throughout the globe, and it is not subject to local causes, to changes by wind and by weather.
Malling-Hansen calls this force "energy of growth"; he supposes that it reaches the earth with the speed of the heat-rays; separates from these, undergoes manifold changes, and, spreading over the whole earth, is the cause of the uniform fluctuations in the growth of all organic life. Upon future investigations falls the burden of proof of this assumption.
This influence of the sun-power may serve as an important factor in testing systems of nourishment, in the arrangement of diet-cures, and in studying the action of mineral waters. For instance, what weight can be attached to an opinion formed on the medicinal value of a mineral spring, if the test be made at a time when the energy of growth is on the decrease, and is thus perhaps assisting in the action of the spring, which at some other period might prove itself only half as efficient?
Good nourishment, a limited amount of mental effort, and as far as possible healthful surroundings during the maximum period of growth of girth, may tend to re-establish the right proportion of stature in children who have grown too rapidly.
There is no known reason to doubt that adults gain and lose in the same periods. If persons who are desirous of growing less stout leave the watering-places at the end of August or earlier, they do so at the time of weight-increase, and a careless diet will hence, in shorter time than it would under similar circumstances in winter, cause them to grow stouter again.
With regard to the school vacations, these should be given from the end of June to the beginning of September, during the two maximum periods of growth; the bodily strength which has been gained will aid the mental work.—Translated for the Popular Science Monthly from Daheim.