I think the sanitarian can now show that any population coming into the tropics can protect itself against these two diseases (malaria and yellow fever) by measures that are both simple and inexpensive; that with these two diseases eliminated life in the tropics for the Anglo-Saxon will be more healthful than in the temperate zones; that gradually, within the next two or three centuries, tropical countries, which offer a much greater return for man's labour than do the temperate zones, will be settled up by the white races, and that again the centres of wealth, civilization, and population will be in the tropics, as they were in the dawn of man's history, rather than in the temperate zone, as at present. Apart from the question of disease, it is far from certain that the white man can ever remain as "fit," as capable of bodily labour, in equatorial regions as in his native temperate conditions, or that his descendants will also maintain the same standard of health and strength. Ordinary non-professional opinion would perhaps discount Colonel Gorgas's forecast as a little too optimistic. FOOTNOTES: [8] "Sanitation of the Isthmus." Mr. J. B. Bishop in _Scribner's Monthly_, February 1913. [9] _Scribner's Monthly_, February 1913, p. 248. [10] _Journal American Medical Association_, July 6, 1907. [11] "Four Centuries of the Panama Canal." [12] See _Scribner's Magazine_, February 1913, p. 251. CHAPTER X. LIFE AT THE ISTHMUS.