CLIMATE IN SOME OF ITS RELATIONS TO MAN 255 



rain and wind; clothe with a view to avoiding chill; live temperately." 

 On the Calcutta docks are painted the words : " Beware of the sun." 



Tropical Diseases. — Certain diseases are so much at home in the 

 tropics that they have come to be known as tropical diseases. This 

 designation, however, does not mean diseases confined to the tropics, 

 but is employed in a meteorological sense for diseases associated with, 

 but not solely, or even necessarily directly due to, high temperatures. 

 Sir Patrick Manson has made it clear that the difference between the 

 diseases of tropics and extra-tropics lies in the specific cause of these 

 diseases. For the development of certain disease germs, tropical tem- 

 peratures are required; or a third organism, other than the disease 

 germ itself and man, may be necessary. If this organism is a tropical 

 species, as in the case of the tsetse fly, the disease is a tropical disease. 

 " The more we learn," Dr. Manson says, " about these [tropical] dis- 

 eases, the less important in its bearing on their geographic distribu- 

 tion, and as a direct pathogenic agency, becomes the role of tempera- 

 ture per se, and the more the influence of the tropical fauna." The 

 fact that plague, and leprosy, and to some extent cholera as well, are 

 practically limited to the tropics, is the result of modern sanitary pre- 

 cautions in the extra-tropics. The unsanitary conditions among 

 tropical peoples favor the spread of these, and similar, diseases, and not 

 the climate per se. Nevertheless, it is clear that these very unsanitary 

 conditions are "more or less an indirect outcome of tropical climate." 



General Conclusions: the Tropics. — All parts of the equatorial zone 

 are not equally disagreeable or hostile to the white race. Many elderly 

 persons, and those who are overworked, may find rest from nervous 

 tension in the enervating climate of the tropics. Much-needed relief 

 from the heat at sea-level may be obtained at tropical mountain sta- 

 tions, and many of these have become well-known health resorts. In 

 India, the hill stations are crowded during the hot months by civilian 

 and military officials, and it has been well said that India is governed 

 from 7,000 feet above sea-level. 



Acclimatization of the White Race in the Tropics. — The acclimati- 

 zation of the white race in the tropics is a question of vast importance. 

 Upon it depend the control, government and utilization of the tropics. 

 It is a very complex problem, and it has been much discussed. It is 

 complicated by race, diet, occupations, habits of life and the like. To 

 discuss it fully is impossible at this time. The gist of the matter is 

 this: white residents from cooler latitudes, on coming into the tropics, 

 must adjust themselves physiologically to the new climatic conditions. 

 During this adjustment there is more or less strain on various organs 

 of the body. The strain may be too severe, then the individual suffers. 

 The adjustment is usually much retarded and hindered by a persistence 

 in habits of food, drink and general manner of living which, however 

 well suited to the home climate, do not fit tropical conditions. Dur- 



