Being at that time the health officer of the city of Havana, and in that capacity having charge of all cases of yellow fever which occurred in the city. I necessarily came in contact with this Board a great deal, and with its various members. I was naturally much interested in the work, and kept in very close touch with it. The Sanitary Department of Havana had a commission of medical men to whom all cases of yellow fever were referred for diagnosis. I was a member of this Commission, and Dr. Carlos Finlay, Dr. Antonio Albertini and Dr. John Guiteras were the other members. Each of us had had a very large practical experience with yellow fever. It is likely, therefore, that our Commission was as accurate in its diagnosis of this disease as it was possible for fallible doctors to be. Most of Dr. Reed’s experimental cases were seen and passed upon by this Commission. Dr. Reed requested us to do so, in order that the diagnosis of his cases might be upon the same footing as the diagnosis of the other cases occurring in the city of Havana. Dr. Carlos Finlay, of Havana, the physician just mentioned as being a member of our Commission, had ever since the year 1881 been investigating, thinking of and writing about the relation of the mosquito to yellow fever. He had convinced himself that this insect was the means whereby the disease was conveyed from person to person. Others before Dr. Finlay’s time had referred to the possibility of this being the case, notably Dr. J. C. Nott, of Mobile, Alabama. In March, 1848, he published in the _New Orleans Medical Journal_ an article in which he maintained that the spread of yellow fever could not be explained by the assumption of a diffusible miasm in the atmosphere. But Dr. Finlay had given more attention to this subject than anyone who had gone before him. He had written upon it constantly from the year 1881. His argument from the then known facts with regard to yellow fever, showing from these facts that it was probably the mosquito that conveyed this disease, was most beautiful and logical. But a still more beautiful piece of reasoning was the induction that it was the stegomyia mosquito, out of the six or seven hundred species of mosquitoes, that conveyed yellow fever.