In 1875, Fedor Lösch described the first proven case of amoebic dysentery in St. Petersburg, Russia. He referred to the amoeba he observed microscopically as "Amoeba coli"; however, it is not clear whether he was using this as a descriptive term or intended it as a formal taxonomic name. The genus "Entamoeba" was defined by Casagrandi and Barbagallo for the species "Entamoeba coli", which is known to be a commensal organism. Lösch's organism was renamed "Entamoeba histolytica" by Fritz Schaudinn in 1903; he later died, in 1906, from a self-inflicted infection when studying this amoeba. For a time during the first half of the 20th century the entire genus "Entamoeba" was transferred to "Endamoeba", a genus of amoebas infecting invertebrates about which little is known. This move was reversed by the International Commission on Zoological Nomenclature in the late 1950s, and "Entamoeba" has stayed 'stable' ever since.