As I have mentioned in a former chapter, when we got through at Havana, we all thoroughly believed that the great virtue of our work there lay in the killing of infected mosquitoes by fumigation. So when we commenced work in the city of Panama, we relied principally upon this method. We carried fumigation in Panama, however, much further than we had ever dreamed of doing at Havana. Beside carrying out the method which we had developed at Havana of fumigating the house where a case of yellow fever had occurred, together with all the contiguous houses, we adopted the following plan. Panama compared with Havana was a very small town. Havana in 1904 had a population of 250,000; Panama, about 20,000. Instead of waiting for the slow process of fumigating the house where a yellow-fever case occurred, with the contiguous houses, and thereby killing the infected mosquitoes concerned in that particular case, we ought to be able, we said, in a small town like Panama to fumigate every house in the city within a comparatively short time, and thereby get rid of all the infected mosquitoes at one fell swoop. [Illustration: Screened Yellow-fever Ward. Ancon Hospital, Panama.] [Illustration: St. Charles Ward, Ancon Hospital. Building in Which Twelve Hundred Frenchmen Died of Yellow Fever.] This would certainly have been the result if our premises had been correct, namely, that it was the fumigation that had caused the disappearance of yellow fever at Havana. With this object in view, we commenced at one end of the city and fumigated every building. It took us about a month to get over the whole town. Cases of yellow fever still continued to occur after we had finished. We therefore went through the procedure a second time. Still other cases occurred, and we went over the city a third time. We used up in these fumigations in the course of about a year some hundred and twenty tons of insect powder, and some three hundred tons of sulphur. These quantities of material give some idea of the amount of fumigation. This draft of one hundred and twenty tons of insect powder represented the whole supply of the United States for a year, and we actually used up at Panama all the insect powder that could be found in the market of the United States. An interesting incident occurred during this first year with regard to insect powder. Knowing that there would be some yellow fever to be dealt with in Colon and Panama, we estimated and made requisition for eight tons of insect powder. The reviewing authorities were very much shocked and surprised at the size of our requisition, and seized upon this one item of eight tons of insect powder to demonstrate the wildness of our estimates. It was some satisfaction to us for the Commission to see that we had not only not been wild and extravagant in our estimates, but that we had been obliged to use actually fifteen times as much as we had estimated for.