[Sidenote:  The problem of acclimatization.]

In all these instances the white race has been successfully transplanted.  It has domiciled itself on the borders of the Tropics and has propagated its kind, though it has abated some of the vigorous qualities which characterized it in its temperate fatherland.  In the real Tropics like India, Cochin China, the Malay Archipelago, and Central Africa, the whole perplexing and urgent problem of European colonization turns on the difficulty or impossibility of acclimatization; and this in turn affects the whole economic, ethnic and political destiny of present colonial holdings.  If acclimatization is impossible, the alternative is an imported ruling class, constantly invalided and as constantly renewed, aided by a similar commercial body acting as superintendents of labor; the whole machine of government and economic exploitation is supported by a permanent servile native population, doing the preeminently tropical work of agriculture, which is so fatal to the white man in a torrid climate.  This means that the conquering white race of the Temperate Zone is to be excluded by adverse climatic conditions from the productive but undeveloped Tropics, unless it consents to hybridization, like the Spaniards and Portuguese of tropical America.  In that national struggle for existence which is a struggle for space, it means an added advantage for the Mediterranean peoples, that they are more tolerant of a torrid climate than the blond Teutons, whose disability in this regard is pronounced; it means that the aptitude of the Chinese for a wide range of climatic accommodation, from the Arctic circle to the equator, lends color to “the yellow peril.”

[Sidenote:  Historical importance of the temperate zones.]

In contrast to the monotonous extremes of climate in the hot and cold zones, temperate lands are characterized by the intermediate degrees of annual temperature and marked seasonal diversity which are so favorable to human development.  In Arctic lands labor is paralyzed by cold as it is by heat in the enervating and overproductive Tropics.  In one, the growing season is too short and ill-favored; in the other, too long to stimulate man to sustained industry.  Hence the Temperate Zones, whose climate avoids both these extremes and abounds in contrasts, whose summers are productive enough to supply food for the winter, and whose winters give both motive and energy for the summer’s work, are richer in cultural possibilities and hence in historical importance.

[Sidenote:  Effects of contrasted seasons.]