Page:Popular Science Monthly Volume 48.djvu/735

Rh will obviously soon be reached if traders and superintendents of native labor are the only colonists who can live there. Moreover, the problem of acclimatization has a great political importance; for if any one of these European nations be possessed of a special physiological immunity in face of the perils of tropical colonization, the balance of power may be seriously disturbed. Or a great menace to the feeble attempts of Europeans to colonize the tropics may exist in the surpassing aptitude of the great Mongol horde, which is perhaps the most gifted race of all in its power of accommodation to new climatic conditions. Africa, Polynesia, and all parts of the earth have now been divided among the nations of Europe. What will they be able to do with them, now that the explorer has finished his work? Because the problem pertains to the sciences of physiology and of anthropology, in no wise lessens its concrete importance for the economist and the statesman.

Before we are in a position to measure even approximately the influence of a change of climate upon the human body and its functions, a number of subordinate confusing factors must be eliminated. Neglect to observe this rule vitiates much of the testimony of observers in the field. In the first place, a change of residence in itself always tends to upset the regular habits of the soldier or the colonist. The temperate youth in England becomes a heavy drinker in the barracks of India; and the Portuguese and Spanish races, predisposed to the use of light wines—ready even to give up the habit if need be—suffer from the disorders incident to alcoholism far less than the English. Inflammation of the liver is indigenous to the tropics; and yet the ofttimes six-fold deadliness of hepatitis among English soldiers in India, compared with the mortality among the native troops from the same disease, is probably due more to the consumption of alcoholic drinks than to the influence of the climate. To this fact is also