In looking back over our ten years of work, these two years of 1905 and 1906 seem the halcyon days for the Sanitary Department. It was really during this period that our work was accomplished. By the fall of 1907 about all of our sanitary work had been completed. Our fight against disease in Panama had been won, and from that time on our attention was given to holding what had been accomplished. One more case of yellow fever occurred in Colon during the following May, but since May, 1906, now more than eight years, not a case of yellow fever has originated on the Isthmus. It is interesting to speculate upon what might have been the result if the recommendation in regard to changing the sanitary officials had been carried into effect. At that time, in June, 1905, most of the physicians who had had experience with yellow fever had not been won over to the truth of the theory of its transmission by the mosquito. It was reported on the Isthmus that one of the most prominent and ablest of these physicians, who did not believe that the mosquito transmission of yellow fever had been proved, and who was convinced that he himself had controlled yellow fever acting upon the filth theory of its causation, had been settled upon as my successor. Had this been the case he would undoubtedly have stopped mosquito work and devoted his attention entirely to cleaning up, as is indicated by the filth theory of the causation of the disease. He would have been the more inclined to this course, as it accorded with the beliefs and prejudices of the authorities on the Isthmus. This would probably have been kept up for two or three years, and there is no reason for believing that our condition on the Isthmus in 1908 would have been any better than was that of the French at the height of their work, when they were having a death-rate of 250 per thousand per year of their employees. It would apparently have been demonstrated that nothing could control yellow fever on the Isthmus, and the belief then generally held that it was the most unhealthy place in the world would have been still further confirmed. And while it is probable that eventually the mosquito theory of yellow fever would have become established somewhere else, its apparent failure at Panama would have given it a blow from which it would have taken years to recover. It seems singular that, after the demonstration at Havana, there should have been any doubt in the mind of anyone with regard to the mosquito transmission of yellow fever. Moreover, the reputation of Dr. Carter, Dr. Ross, Mr. Le Prince and myself, as sanitary officials, would have been irretrievably ruined. We took a tremendous risk and came very near failing from causes hinted at in the foregoing pages.