gorged itself with the blood of a yellow fever patient. Note that he did this with the expectation, indeed with the hope, that he would thus be infected with one of the deadliest of diseases. He sought to prove not that there was no danger in a mosquito bite, but on the contrary that there was the greatest possible danger. And his anticipations were fully realized. In due time after the bite he was stricken with yellow fever in a particularly severe form; from which, however, he happily recovered.

Dr. Lazear came next. At about the same time with Carroll he made a similar experiment upon himself. Apparently the insect by which he caused himself to be bitten had not itself been infected. At any rate Lazear did not develop the disease. At this he was disappointed, and he determined to expose himself again. Accordingly he was thoroughly bitten by another mosquito, in the yellow fever ward of the hospital. He noted the fact and all its results most carefully, as though he had been experimenting upon some inanimate object. In due time the disease manifested itself in its most malignant form. Everything possible was of course done for him, but in vain. He died of the disease which he had voluntarily contracted for the sake of saving others from it; one of the world's great martyrs to the cause not merely of science but of humanity.

So Camp Lazear was founded and was named after this hero. There were erected two large frame buildings, one for infected mosquitoes and one for infected clothing. The mosquito building was divided into two parts by a permanent wirecloth partition, impervious to even the smallest mosquito, but of course permitting free circulation of air. All the windows and doors were securely screened in like manner, so that it was impossible

for mosquitoes to pass in or out. This building was ventilated in the most thorough manner. Three men entered it and lived there for a fortnight. One of them entered the compartment which was infested with feverinfected mosquitoes, and was bitten by them. The others remained in the other compartment which was free from mosquitoes but through which the same air circulated and in which all other conditions were identical with those in the insect room. The result was that the man who was bitten developed the fever, while the others, though fully as susceptible to it as he, showed no signs of it. Such was the convincing demonstration of the mosquito house.

The clothing building was kept free from mosquitoes, but was well stocked with the clothing and bedding of yellow fever patients. There were the beds in which men had died of the fever, soiled with their vomit and other excreta. The room was purposely deprived of ventilation, so that its air should constantly be heavy with the reek of disease and death. Into that indescribably loathsome place brave men entered, and there they lived for weeks, wearing the soiled clothing and sleeping in the soiled beds of those who had died of the pestilence. But not one of them contracted the fever. Not one sickened. All emerged from the noisome place at the end of the experiment in perfect health. Such was the convincing demonstration of the infected clothing house.

One thing more remained. There was one remote possibility that the men who had remained free from the fever, in the noninfected room of the mosquito house and in the infected clothing house, were in some unsuspected way immune against the disease. To determine this, one of each of the companies permitted himself to

be bitten by an infected mosquito, with the result that he promptly developed the disease. That was the final, complete and crowning demonstration which made Camp Lazear forever famous in the annals of humanity. At a single stroke the pestilence which had been the haunting horror of the tropics was potentially conquered. Dr. Reed proclaimed to the world that the specific agent in the causation of yellow fever was a germ or toxin in the blood of a patient during only the first three days of the attack, which must be transmitted by the bite of a mosquito inflicted upon its victim at least twelve days after taking it from the blood of the first patient. In no other way was it possible to convey the infection. The notion that it was conveyed through the air, in the breath of patients, in their soiled clothing or the discharges of their bodies, was baseless.

That historic achievement was alone sufficient to make that first year of General Wood's administration in Cuba forever gratefully famous. Of course the lesson thus learned was at once put into effect with all possible thoroughness. War was declared upon the death-dealing mosquito. In February, 1901, the campaign was begun by Major William C. Gorgas, U. S. A., the chief sanitary officer of Havana. Every case of yellow fever was immediately reported, and the patient was rigidly isolated during the three days in which his blood was infective. All the rooms of his house and the adjacent houses were closed to prevent the escape of possible infected mosquitoes, and were then thoroughly fumigated so as to destroy every insect within them. In this way the spread of the disease was prevented. At the same time measures were taken to exterminate the mosquitoes altogether, by depriving them of breeding places. It was ascertained that the insect required for propagation

a certain amount of stagnant water, in which its eggs might be deposited and hatched. Steps were therefore taken to drain or otherwise get rid of all pools, or to apply to them a film of oil which would prevent the

STREET IN VEDADO, SUBURB OF HAVANA

insects from using them, and to screen carefully all vessels and other receptacles in which water was necessarily kept. These were the same methods which Major -since Major General-Gorgas a few years later applied with distinguished success for the elimination of yellow fever from the Isthmus of Panama and thus rendered possible the construction of the interoceanic canal.

Begun in February, 1901, this work in Havana was so vigorously and skilfully prosecuted that before sum