THE HYGIENE OF THE ZONES 178 Introduction: some general relations of climate and health—A complex subject—Climate, micro-organisms, and disease—Geographical distribution of disease— Tropics: general physiological effects—Tropical death-rates—Hygiene in the tropics—Tropical diseases—Malaria—Yellow fever—Dysentery: diarrhœal disorders—Tropical abscess of the liver—Cholera—Plague —Sunstroke and related conditions—Dengue—Beri-beri—Other minor diseases—General conclusions: tropics—Temperate zones: general—Winter and summer diseases—Tuberculosis —Pneumonia—Diphtheria—Influenza—Bronchitis—Rheumatism —Measles and scarlet fever—Typhoid fever—Whooping cough —Cholera infantum—Hay fever—Polar zones: general—Scurvy —Climate and health: general conclusion.