The hurricanes and other great wind storms are probably no more frequent nor more destructive than are cyclones in the States. In Porto Rico there is a belief that a single severe hurricane occurs about once in each hundred years. Insects are strangely few. The mosquito is grown in the cisterns, and is abundant in the towns. It is practically absent in the country. The flea is found only in the towns, where it is a sort of domestic animal. A little attention to cleanliness would diminish the numbers. The bedbug has not been seen in a year in Porto Rico, though there is no reason why it should not be here. Centipedes, spiders and tarantulas are so scarce that the natives expect about fifty centavos for each large specimen which they catch. Indeed, instead of an abundance of insects, these islands are remarkable for the small number of species and individuals indigenous to them. Recent inventions and discoveries have made the conquest of the Tropics by the Caucasian race possible. There have been great discoveries made in chemistry, biology, bacteriology and medicine within recent years. Chemical discoveries have produced new and powerful remedies. Biology and bacteriology have brought to light numerous microscopic forms of life, traced their life histories, and shown that beyond a doubt, many, if not all, of the diseases designated communicable (contagious and infectious) are due to living beings called ‘germs.’ The experimental physician has discovered, in some cases, remedies which will destroy these germs after they have been introduced into the body, while the sanitarian has made vast studies in demonstrating how they may be destroyed before entering the body. Thus, sterilized food, water and clothing never convey diseases. Cities which are kept clean and have pure water supplies have little fear of epidemic diseases. The draining of lowlands, the thorough cultivation of the soil, the paving of streets and the use of quinine cause malaria to retreat from its old haunts. Biologists have shown that a tick conveys the Texas cattle fever; the tsetse fly in Africa spreads the ‘fly disease’ among the cattle in that continent. The house-fly spread typhoid fever among our soldiers last summer, and there is good reason for believing that the mosquito is in large part the disseminator of malaria. Consumption, dysentery, the Asiatic plague, leprosy, typhoid fever, are all germ diseases. Knowing the causes of these diseases, the life history of the germs, and the remedies to apply, it is hoped that in a very few years the biologist, the bacteriologist, the sanitarian, all working together, will make tropical diseases to be no more dreaded than are the diseases of temperate regions. As warm countries become better known, physicians will certainly become more skillful to treat the diseases peculiar to them.