544 POPULAR SCIENCE MONTHLY. 



by thunder and lightning. The ground soon dries off, and the rain 

 has occasioned no inconvenience of consequence to anyone. The ab- 

 sence of thunder and lightning is remarkable. This is certainly true 

 in Porto Rico. 



The hurricanes and other great wind storms are probably no more 

 frequent nor more destructive than are cyclones in the States. In Porto 

 Eico 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 bed- 

 bug 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 in- 

 dividuals indigenous to them. 



Recent inventions and discoveries have made the conquest of the 

 Tropics by the Caucasian race possible. There have been great dis- 

 coveries 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 commun- 

 icable (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 'fry 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 



