museum, 1902; curator, 1903; and has been a member of the Yellow Fever Board, since 1900.
The principal public service which Dr. Carroll has rendered to the science of medicine, is his voluntary submission to the bite of an infected mosquito by which he became the first case of known "experimental yellow fever" on record. His life was despaired of for three days. The mosquito which conveyed the poison had previously been caused to bite three well-marked cases of yellow fever. This experiment on Dr. Carroll was undergone by him in order to justify experimentation on other people. It took place while he was associated with the late Major Walter Reed, surgeon of the United States army, in study of Sanarelli's supposed yellow fever bacillus, from 1897-1902. Dr. Carroll demonstrated in 1903 that the Myococcidium stegornyiæ (so-called), found in yellow fever mosquitos and supposed to be the parasite of that disease, was, in reality, a yeast cell. The scientific investigations in which he took part and in which Dr. Jesse W. Lazear lost his life have led to the demonstration of the fact that natural yellow fever is contracted only through the bite of a special mosquito; that the disease is transmissible by blood injection, and that the parasite of the disease is, in all probability, ultra-microscopic.
Dr. Carroll has been the vice-president of the American Society of Bacteriologists; he is an honorary member of the American Society of Tropical Medicine, since 1903; member of the International Congress of Arts and Sciences, St. Louis, 1904. He has been in the army continuously since January 9, 1874; he was for more than twenty-four years "an enlisted man," serving four and one-half years as contract surgeon, and since October, 1902, as first lieutenant and assistant surgeon.
Several of his technical papers on yellow fever have been published in current medical periodicals.
He is a member of the Episcopal church; his favorite reading has been the lives of eminent men. He is a Royal Arch Mason. He is not identified with any political party. He says that he has "had no relaxation for twelve years, but was formerly fond of shooting, swimming, walking, and riding." At one time he used dumbbells constantly for five years by way of physical exercise. His love of adventure prompted him to become a soldier, and he chose the profession of medicine because he desired to know some-
