The reappearance of yellow fever in Cuba after its apparent extinction a few months ago, without its introduction from outside, or, in fact, its occurrence in any of the seaports or larger towns, is an event of much interest and raises the question of how this disease can lie dormant for such considerable periods of time. So inconsistent does this phenomenon appear with the accepted method of transmission by the Stegomyia calopus that some doubting Thomases have been inclined to revert to that half-way house on the road to conversion, the "not the only way" doctrine. To understand clearly conditions in Cuba it is necessary to review briefly the application there of the theory of Finlay and Reed.
In 1901, under the Military Government of Intervention, sanitary measures directed especially against yellow fever (mosquito work, etc.) were carried on in only a few of the larger towns. There was no