To accomplish this we required all cases of yellow fever in the city to be reported to the central office of the Health Department. They were at once seen by the official diagnosis commission, and if pronounced yellow fever, were at once moved to Las Animas Hospital in a carefully screened ambulance and placed in screened wards. The routine at Las Animas Hospital precluded the possibility of any mosquitoes biting the patient. Most of the Americans, and in fact patients of all classes, preferred to go to Las Animas. Under Dr. Ross’s care the hospital soon obtained the reputation of saving more yellow-fever patients than could be done at the other hospitals, or at their homes. This reputation was justly acquired. The statistics of this hospital amply bore out the reputation which public opinion gave it. If the patient elected, he could stay in his own home, the room or rooms to be screened were agreed upon, a skilled force of carpenters were sent by the central sanitary office, who thoroughly and carefully screened the designated apartments. Only one point of exit and entrance was left, and this was protected by a vestibule and double door. A number of squads of carpenters, each furnished with its own wagon loaded with the necessary wire netting, lumber, and other material, were always on duty, so that usually within an hour after notice came to the central office night or day, the patient was either removed to the hospital or was being screened at his own home. To see that sanitary regulations were carried out and that only authorized persons were admitted within the screened quarters of the patient, an officer of the Sanitary Department was always on duty. He sat in the vestibule and required that one door should be closed always before the second was opened. He was changed every eight hours, that is, he was on duty only eight hours in each twenty-four. We soon found that this method could not be carried out in its entirety; that it was the exception that we could get hold of a patient during his initial chill. Generally the patient had been sick one or two days before he came under our observation. It was evident, therefore, that a number of mosquitoes might have bitten him before he was discovered and cared for. As it would be twelve or fourteen days before these mosquitoes would become infectious, we had plenty of time to attend to them. From the known habits of the stegomyia mosquito we did not think they would leave the house in which they had become infected, though in an individual case this might occur, and a mosquito wander into a contiguous house. [Illustration: Stegomyia Squad. Havana.] [Illustration: Screened Water Barrel. Havana.]