Page:Popular Science Monthly Volume 48.djvu/746

674 the only alleviating circumstance in Jamaica, where the fierce sea breezes by day, reversing at night, have made life for the English possible. Singapore owes its prosperity to the fact that it is the only place in the East Indies where malaria is completely unknown. Similarly, wherever there are alternating seasons of heat and cold, the chance of acclimatization becomes greater. Hence one advantage of the climate of plateaus in the tropics, since both daily and seasonal variations are very great. Even in the major part of the African plateau, however, the elevation can not overset the monotony of the tropical climate, the seasonal variations ranging much lower than ours, while the mean temperature is fifty per cent higher.

Altitude, while giving at least temporary relief to the white race, seems to exert a peculiarly baneful effect upon the negro and the Indian. Dr. Spruce gives an interesting example of great economic distress produced by it in South America. Coffee grows in the zone from four thousand to six thousand feet, and the demand for native labor is very great. Indians coming from above die of dysentery, while if they come from the coast they succumb to respiratory diseases, so that the planters are severely hampered. It is said in our Southern States that the negro can not go from the hill country to the plains without great physiologic disturbance. Jousset declares that the elevation of three thousand to forty-five hundred feet proves fatal to the negro in Africa. This, of course, is due in part to the greater sensitiveness of all primitive peoples to climatic changes, and partly due to lack of hygiene. But that the negro by nature really lacks a power of accommodation, even in the tropics, in this respect is conceded by most observers;