Another English physician who had not been in malarial regions allowed himself to be bitten by infected mosquitoes sent from a malarial locality. In due time he developed the fever. Many other experiments made in various places might be cited. The results have all been practically the same. To-day the soldiers of many civilized nations are required to protect themselves from mosquitoes because it has been found that it pays. Disease has always been a worse terror than bullets in any war, and we are fast learning that the great loss from diseases heretofore considered unavoidable may be very largely eliminated by proper sanitary arrangements and protection from noxious insects. CHAPTER VIII MOSQUITOES AND YELLOW FEVER Yellow fever is a disease, principally of seaport towns, from which the United States has suffered more than any other country. It is endemic only in tropical regions but is often carried to subtropical, sometimes even to temperate zones where, if the proper mosquitoes exist, it may rage until frost. Vera Cruz, Havana, Rio de Janeiro, and the west coast of Africa were long regarded as permanent endemic foci, the disease appearing there in epidemic form from time to time, often spreading to other ports in more or less close communication with such places. In the United States the Gulf states have been the greatest sufferers from the disease, although it has spread as far as Baltimore, Philadelphia and Washington, where at rare intervals it was most serious, abating its ravages only when frost came. The last severe outbreak occurred in New Orleans in 1905 when eight thousand cases and nine hundred deaths occurred. At that time there was waged one of the most remarkable warfares against death in its most terrifying form that the world has ever known. And, thanks to the achievements of science, particularly to the investigations of three men, one of whom gave his life to the cause, the fight was successful and this dreadful outbreak was checked just at the time when according to all precedent it should have been at its height. This result which at other times and under other conditions would have been considered miraculous was achieved not by the usual custom of isolation, quarantine, etc., but by a direct, we may almost say hand to hand, conflict with mosquitoes: the mosquitoes belonging to a particular genus and species, _Stegomyia calopus_ (_fasciata_). Before taking up a discussion of this achievement in New Orleans let us consider first the work of the men that made such results possible.