i6z THE POPULAR SCIENCE MONTHLY. 



are kept in sweat-boxes, asking in vain for water and fresh air ; illus- 

 trated almanacs implore us to fortify our constitutions with patent 

 brandy " a reliable febrifuge, and in malarious districts the only safe 

 beverage." 



Considering the problem from a purely inductive standpoint, we 

 shall find that fruits and fevers are not necessarily concomitant. Some 

 two hundred millions of our fellow-men stick to a frugal diet in the 

 swampiest districts of the intertropical regions, and yet enjoy a great- 

 er immunity from periodical fevers than the inhabitants of our North- 

 ern seaport towns. Siam, the Punjaub, the Brazilian forest-province 

 of Entre-Rios, and the swampy peninsula of Yucatan, would be the 

 healthiest regions of this planet if the absence of what we call malarial 

 diseases could be accepted as a safe criterion ; but the accounts of 

 former travelers show that the same diseases were entirely unknown 

 in regions which are now justly dreaded by visitors from the North. 

 In the valley of the Amazon, and on the larger islands of the West 

 Indian archipelago, fevers made tbeir first appearance with the advent 

 of European colonists. The natives of Sierra Leone, Dr. Schweinfurth 

 tells us, call swamp-fever the " English sickness " a disease confined 

 to foreigners. The Portuguese and Italians, people with a natural 

 predilection for a frugal diet, survive where beef -eaters die by hun- 

 dreds. In Mexico, where several coast-towns have become interna- 

 tional seaports, vegetarians are almost the only permanent foreign 

 residents ; native domestics, who share the flesh-pots of their foreign 

 employers, die by scores every summer. But the necessity of such a 

 result might have been inferred from an a priori axiom which seems 

 to have been no secret to the ancient inhabitants of Southern Europe, 

 viz., that in a warm climate calorific food is incompatible with the 

 constitution of the human body. The word fever (Latin febris) and 

 its equivalents in several other languages (Greek -nvpt^ic, Spanish and 

 Italian calenturd) are derived from adjectives meaning fervid hot or 

 heated thus indicating the chief characteristic, and, according to the 

 ancient Greek and modern Spanish theory, also the chief cause, of all 

 pyrexial disorders. Man is a native of the tropics, and like our next 

 relatives, the anthropoid four-handers, our primogenitor subsisted 

 probably on fruits and water i. e., on a refrigerating diet. In subse- 

 quent ages several tribes of the human race emigrated to regions 

 whose climate requires calorific food and warm clothing. On return- 

 ing to the birth-land of their race these wanderers often persist in 

 habits compatible only with a low temperature : the combined influ- 

 ence of a warm climate, warm clothing, and calorific food overcomes 

 the vital power of resistance ; the inability of the system to preserve 

 its due mean temperature induces the blood-changes which character- 

 ize the symptoms of climatic fevers the overheated blood ferments. 

 Humid heat accelerates the disintegrating process ; but that humid- 

 ity is only an adjuvant and not even a necessary adjuvant cause, is 



