Chancre of the gum is one of the rarest of extragenital chancres. In the majority of textbooks and atlases on dermatology and syphilis the subject is either not mentioned at all, or is dismissed with the statement that the lesion is a rare one. In Fournier's 1 volume "Les chancres extra-genitaux," and in Thouvenot's 2 "These," gum chancres are more comprehensively described than in any other report that I have been able to find in the literature. In Power and Murphy's "System of Syphilis" and in Zinsser's excellent atlas of oral syphilis the lesion is briefly mentioned, and in this atlas there is no illustration of this type of chancre. Indeed there is a great paucity of illustrations of gum chancre in the literature. According to Thouvenot, the earliest recorded mention of gum chancre was by Astruc in 1736 and later in 1768 by Fabvre. The first recorded case report was in the same year by Swediaur. This writer records the case of a young woman who through an accident lost a tooth which a dentist replaced with a tooth extracted from an apparently healthy subject. Later the young woman developed a syphi¬ litic ulcération at the site of the replaced tooth. Reports of gum chancres by the older writers are difficult of analysis. Prior to the time of Rollet (1858), chancre was regarded as belonging to one of two types, one infected and the other noninfected. This view involved the well-known controversy concerning the unity and duality theories of chancroid and chancre. In 1893, Bulkley • collected 9,058 recorded cases of extragenital chancres from the literature, the localization of which, in part, was: 1,810 cases, or 19.9 per cent., were labial ; 1,148 cases, or 12.6 per cent., were breast chancres; 307 cases, or 3.2 per cent., were tonsillar; 157 cases, or 1.7 per cent., were lingual; 42 or, 0.46 per cent., were gum chancres. In 1897, Muncheimer * made an analysis of extragenital