The general form of the microscope featured here is is neither like the one illustrated in this 1892 Bézu, Hausser catalogue, and not yet like in the 1898 Nachet catalogue. It's seems is an Intermediate form between the old company and the Nachet firm.
In his 1898 catalogue, Nachet kept only one microscope of the former firm Hartnack/Bézu and Hausser. It was described as "Grand Modèle numéro 5" (pages 24-25). This microscope was the “Microscope spécial pour l’étude des bactéries” (L) in the Bézu, Hausser et Cie catalogue in 1892.
Note the similiarity between this microscope and the two flanking instruments.