become striking, stimulating, productive of important economic and political results, when close juxtaposition enables them to react sharply one upon the other.  In effecting these nice differentiations of local types, climate is nearly always one of the factors at work, emphasizing perhaps an existing ethnic difference.  Even the slight variations of temperature to be found in the same zone or the same climatic region produce distinct results, especially where they are harnessed, as is usually the case, with some other geographic condition of relief, area or soil, pulling in the same direction.  Mexico, Peru, Italy, Switzerland, Greece and Asia Minor, with its high plateau interior and its contrasted Euxine and Aegean coasts, represent each a complex of climatic differences, which, reinforced by other geographic factors, have made in these regions a polychrome picture of national life.

[Sidenote:  Effect of climate upon distribution of immigration]

Climatic contrasts aid differentiation also by influencing both natural and artificial selection in the distribution of peoples.  This effect is conspicuous in the distribution of immigrants in all colonial lands like Africa, South America and in every part of the United States.[1427] The warm, moist air of the Gulf and South Atlantic States is attracting back to the congenial habitat of the “black belt” the negroes of the North, where, moreover, their numbers are being further depleted by a harsh climate, which finds in them a large proportion of the unfit.  The presence of a big negro laboring class in the South, itself primarily a result of climate, has long served to exclude foreign immigration, which sought therefore the unoccupied lands and the congenial climate of the more bracing North.  Hence it is both a direct and indirect effect of climate that the North shows a large proportion of aliens, and the white population of the South an almost unadulterated English stock.

[Sidenote:  Climate and race temperament.]

The influence of climate upon race temperament, both as a direct and indirect effect, can not be doubted, despite an occasional exception, like the cheery, genial Eskimos, who seem to carry in their sunny natures an antidote to the cold and poverty of their environment.  In general a close correspondence obtains between climate and temperament.  The northern peoples of Europe are energetic, provident, serious, thoughtful rather than emotional, cautious rather than impulsive.  The southerners of the sub-tropical Mediterranean basin are easy-going, improvident except under pressing necessity, gay, emotional, imaginative, all qualities which among the negroes of the equatorial belt degenerate into grave racial faults.  If, as many ethnologists maintain, the blond Teutons of the north are a bleached out branch of the brunette Mediterranean race, this contrast in temperament is due to climate.  A comparison of northern and southern peoples of the