The discovery by Schaudinn and Hoffmann1 in 1905 of a spirillum in various luetic lesions marked the beginning of a decided advance in our knowledge of the etiology of syphilis. The announcement of the discovery, while most conservative in its assertions, gave a fresh impetus to the study of the many phases presented in the parasitology and pathology of this disease. A wide-spread interest was awakened and many investigators directed their attention to the problems in this new field of research. From the results of many of their observations we have already gained a new conception of the cause, course and treatment of lues.
The organism found by Schaudinn and Hoffmann was first described by them under the name of Spirochæta pallida, but a more intimate study of its morphology led them to forsake its classification under the spirochætæ and to rename it the Treponema pallidum. Much