Page:Popular Science Monthly Volume 20.djvu/174

162 are kept in sweat-boxes, asking in vain for water and fresh air; illustrated 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 greater immunity from periodical fevers than the inhabitants of our Northern 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 their 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 hundreds. In Mexico, where several coast-towns have become international 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 πύρεξις, Spanish and Italian calentura) 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 subsequent ages several tribes of the human race emigrated to regions whose climate requires calorific food and warm clothing. On returning to the birth-land of their race these wanderers often persist in habits compatible only with a low temperature: the combined influence 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 characterize the symptoms of climatic fevers—the overheated blood ferments. Humid heat accelerates the disintegrating process; but that humidity is only an adjuvant and not even a necessary adjuvant cause, is