the Army, he served in Arizona, Nebraska, Dakota, and in the Southern and Eastern States.

According to the exigencies of the service he was moved frequently from station to station, everywhere recognized by men of his own age as a charming and sympathetic companion, and by older officers as an earnest and intelligent physician whose industry, fidelity to duty, and singularly good judgment gave brilliant promise for the future. In the poor cabins and dugouts of the pioneers in the sparsely settled districts where he served his flag Reed was ever a messenger of healing and comfort. At that time army posts on the frontier were usually remote and with small garrisons. The young medical officer, generally the only one at the station, was called upon by the settlers for miles around. Without help, and with only such instruments and medicines as could be hastily stuffed in his saddlebag, he was summoned to attend a fractured thigh, a child choking with diphtheria, or, most trying of all, a complicated childbirth.

Such experience schools well in self-reliance, and in the formation of quick and accurate observation.

For a man like Reed, already an earnest student, no better preparation could perhaps have been had. His earlier army service must have singularly tended to develop in him the very qualities most necessary to his final success. To the end of his life it was noticeable that even when he had long given up the practice of medicine for the work of the laboratory, he was nevertheless unexcelled at the bedside for rapid, unerring diagnosis and sound judgment in treatment. So also were the series of experiments which robbed yellow fever of its terrors especially remarkable for simplicity, accuracy, and completeness, or they never would have so quickly convinced the world of their truth. Too much reverence for accepted teachings and too little experience in grappling with difficulties unassisted and they might never have been conceived or carried out.

In 1890 he was assigned to duty in Baltimore and remained there over a year. Here he had the great advantage of working in the laboratories of Johns Hopkins University and the happiness of winning the close friendship of his distinguished teacher, Prof. William H. Welch.

In 1893 Reed was promoted surgeon with the rank of major, and in the same year was detailed in Washington as curator of the Army Medical Museum and professor of bacteriology at the newly organized Army Medical School. Here he worked industriously at his specialty and wrote many valuable monographs, all characterized by accuracy and originality. His excellent judgment made him especially valuable in investigating the causes of epidemic diseases at military posts and in making sanitary inspections. He was therefore frequently selected for such work, which, with his duties as teacher

and member of examining boards, occupied much of the time that he would otherwise have spent in his laboratory. Here again it seems that duties which must often have been irksome were specially fitting him for his culminating work.

During the Spanish-American war the camps of the volunteer troops in the United States were devastated by typhoid fever, and Major Reed was selected as the head of a board to study the causation and spread of the disease. This immense task occupied more than a year's time. With the utmost patience and accuracy the details of hundreds of individual cases were grouped and studied. The report of the commission, now in course of publication by the Government, is a monumental work which must always serve as a basis for future study of the epidemiology of typhoid fever.

The most original and valuable work of the board is the proof that the infection of typhoid fever is spread in camps by the common fly and by contact with patients and infected articles-clothing, tentage, and utensils as well as by contaminated drinking water.

In June, 1900, Major Reed was sent to Cuba as president of a board to study the infectious diseases of the country, but more especially yellow fever. Associated with him were Acting Asst. Surgs. James Carroll, Jesse W. Lazear, and A. Agramonte.

At this time the American authorities in Cuba had for a year and a half endeavored to diminish the disease and mortality of the Cuban towns by general sanitary work, but while the health of the population showed distinct improvement and the mortality had greatly diminished, yellow fever apparently had been entirely unaffected by these measures. In fact, owing to the large number of nonimmune foreigners, the disease was more frequent than usual in Habana and in Quemados, near the camp of American troops, and many valuable lives of American officers and soldiers had been lost.

Reed was convinced from the first that general sanitary measures alone would not check the disease, but that its transmission was probably due to an insect.

The fact that malarial fever, caused by an animal parasite in the blood, is transmitted from man to man through the agency of certain mosquitoes had been recently accepted by the scientific world; also, several years before, Dr. Carlos Finlay, of Habana, had advanced the theory that a mosquito conveyed the unknown cause of yellow fever, but did not succeed in demonstrating the truth of his theory.

Dr. H. R. Carter, of the Marine-Hospital Service, had written a paper showing that although the period of incubation of yellow fever was only five days, yet a house to which a patient was carried did not become infected for from fifteen to twenty days.

To Reed's mind this indicated that the unknown infective agent has

to undergo a period of incubation of from ten to fifteen days, and probably in the body of a biting insect.

Up to this time the most generally accepted theory as to the causation of yellow fever was that of Sanarelli, who claimed that the bacillus icteroides, discovered by him, was the specific agent of the disease. Major Reed, in association with Doctor Carroll, had, however, already demonstrated that this bacillus was one widely disseminated in the United States and bore no special relation to yellow fever. In June, July, and August, 1900, the commission gave their entire attention to the bacteriological study of the blood of yellow-fever patients and the post-mortem examination of the organs of those dying with the disease. In 24 cases where the blood was repeatedly examined, as well as in 11 carefully studied autopsies, bacillus icteroides was not discovered nor was there any indication of the presence in the blood of a specific cause of the disease.

Application was made to Gen. Leonard Wood, the military governor of Cuba, for permission to conduct experiments on nonimmune persons and a liberal sum of money requested for the purpose of rewarding volunteers who would submit themselves to experiment.

It was indeed fortunate that the military governor of Cuba was a man who by his breadth of mind and special scientific training could readily appreciate the arguments of Major Reed as to the value of the proposed work.

Money and full authority to proceed were promptly granted, and to the everlasting glory of the American soldier, volunteers from the Army offered themselves for experiment in plenty, and with the utmost fearlessness.

Before the arrangements were entirely completed, Doctor Carroll, a member of the commission, allowed himself to be bitten by a mosquito that twelve days previously had filled itself with the blood of a yellow-fever patient. He suffered from a very severe attack, and his was the first experimental case. Doctor Lazear also experimented on himself at the same time, but was not infected. Some days later, while in the yellow-fever ward, he was bitten by a mosquito and noted the fact carefully. He acquired the disease in its most terrible form and died a martyr to science and a true hero. No other fatality occurred among the brave men who, in the course of the experiments, willingly exposed themselves to the infection of the dreaded disease.

A camp was especially constructed for the experiments about 4 miles from Habana, christened Camp Lazear in honor of the dead. comrade. The inmates of the camp were put into most rigid quarantine and ample time was allowed to eliminate any possibility of the disease being brought in from Habana,

The personnel consisted of three nurses and nine nonimmunes, all in the military service, and included two physicians.

From time to time Spanish immigrants, newly arrived, were brought in directly from the immigrant station; a person not known to be immune was not allowed to leave camp, or if he did was forbidden to return.

The most complete record was kept of the health of every man to be experimented upon, thus eliminating the possibility of any other disease than yellow fever complicating the case.

The mosquitoes used were specially bred from the eggs and kept in a building screened by wire netting. When an insect was wanted for an experiment it was taken into a yellow-fever hospital and allowed to fill itself with the blood of a patient; afterwards at varying intervals from the time of this meal of blood it was purposely applied to nonimmunes in camp.

In December five cases of the disease were developed as the result of such applications; in January, three, and in February, two, making in all ten, exclusive of the cases of Doctors Carroll and Lazear. Immediately upon the appearance of the first recognized symptoms of the disease, in any one of these experimental cases, the patient was taken from Camp Lazear to a yellow-fever hospital, 1 mile distant. Every person in camp was rigidly protected from accidental mosquito bites, and not in a single instance did yellow fever develop in the camp, except at the will of the experimenters.

The experiments were conducted at a season when there was the least chance of naturally acquiring the disease, and the mosquitoes used were kept active by maintaining them at a summer temperature. A completely mosquito-proof building was divided into two compartments by a wire screen partition; infected insects were liberated on one side only. A brave nonimmune entered and remained long enough to allow himself to be bitten several times. He was attacked by yellow fever, while two susceptible men in the other compartment did not acquire the disease, although sleeping there thirteen nights. This demonstrates in the simplest and most certain manner that the infectiousness of the building was due only to the presence of the insects.

Every attempt was made to infect individuals by means of bedding, clothes, and other articles that had been used and soiled by patients suffering with virulent yellow fever.

Volunteers slept in the room with and handled the most filthy articles for twenty nights, but not a symptom of yellow fever was noted among them, nor was their health in the slightest degree affected. Nevertheless they were not immune to the disease, for some of them were afterwards purposely infected by mosquito bites.

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This experiment indicates at once the uselessness of destroying valuable property for fear of infection. Had the people of the United States known this one fact a hundred years ago an enormous amount of money would have been saved to householders.

Besides the experimental cases caused by mosquito bite, four nonimmunes were infected by injecting blood drawn directly from the veins of yellow-fever patients in the first two days of the disease, thus demonstrating the presence of an infectious agent in the blood at this early period of the attack.

Even the blood serum of a patient, passed through a bacteria-proof filter, was found to be capable of causing yellow fever in another person.

The details of the experiments are most interesting, but it must here suffice to briefly sum up the principal conclusions of this admirable board of investigators, of which Reed was the master mind:

1. The specific agent in the causation of yellow fever exists in the blood of a patient for the first three days of his attack, after which time he ceases to be a menace to the health of others.

2. A mosquito of a single species, Stegomyia fasciata, ingesting the blood of a patient during this infective period is powerless to convey the disease to another person by its bite until about twelve days have elapsed, but can do so thereafter for an indefinite period, probably during the remainder of its life. 3. The disease can not in nature be spread in any other way than by the bite of the previously infected Stegomyia. Articles used and soiled by patients do not carry infection.

These conclusions pointed so clearly to the practical method of exterminating the disease that they were at once accepted by the sanitary authorities in Cuba and put to the test in Habana, where for nearly a century and a half by actual record the disease had never failed to appear annually.

In February, 1901, the chief sanitary officer in Habana, Maj. W. C. Gorgas, Medical Department, U. S. Army, instituted measures to eradicate the disease, based entirely on the conclusions of the commission. Cases of yellow fever were required to be reported as promptly as possible, the patient was at first rigidly isolated, and immediately upon the report a force of men from the sanitary department visited the house. All the rooms of the building and of the neighboring houses were sealed and fumigated to destroy the mosquitoes present. Window and door screens were put up, and after the death or recovery of the patient his room was fumigated and every mosquito destroyed. A war of extermination was also waged against mosquitoes in general, and an energetic effort was made to diminish the number bred by draining standing water, screening tanks and vessels, using petroleum on water that could not be drained, and in the most systematic manner destroying the breeding places of the insects.