On the next hill, about a quarter of a mile from the old yellow-fever wards of Ancon Hospital, is the Tivoli Hotel. This hotel is owned and operated by the Canal Commission, and for the last few years has been filled with visitors from abroad, principally from the United States, who were of course entirely unacclimated. During the months of the dry season the hotel is crowded, and for the last two years it has been kept full nearly all the year round. During these last two years about thirty thousand sight-seers have visited the Isthmus. [Illustration: Stoned Ditch near Tivoli Hotel. Ancon, Panama.] [Illustration: Bad Anopheles Breeding-ground on Artificial Fill. La Boca.] This hotel is practically unscreened. While the doors and windows are provided with screens, such screening, where there are many doors and windows, is so imperfect that in the tropics it gives little protection against yellow fever and malaria. No attempt at all was made to screen the galleries of this hotel. Hundreds of visitors spent the whole evening on these galleries until twelve and one o’clock at night, yet we had no cases of yellow fever or malaria developing from such exposure. If this had occurred ten years before and three hundred of these unacclimated visitors from the United States had sat for an hour or two after sunset on this gallery, exposed to the deadly night air, it would probably have meant that every single one of them would have contracted fever, and a considerable number of them would have died. The only difference between now and then is that we have drained and cleaned the country around this hotel, so that now there are no pools or puddles, or places of any kind within two hundred yards of the hotel where mosquitoes can breed, and consequently there are no mosquitoes. The fact that unacclimated non-immunes can live in the Tivoli Hotel without contracting fever is evidence that we could do without screening in our wards at the hospital, but we thought it unwise to do away with the wire netting there. We thought it equally unwise not to screen the Tivoli Hotel, but the expense was large, and the architect thought it would mar the appearance of the building, so it was left off by the authorities, in spite of my advice on the subject. The first guests in the Tivoli Hotel were President Roosevelt and his party, who were there in November, 1906. I succeeded in getting the authorities to screen thoroughly the portion of the building occupied by the President.