A treatment device (1) for treating histological or cytological samples has a plurality of containers (6) for different treatment agents and a detection apparatus (2) for detecting a code which unequivocally identifies a type of a treatment agent or a type of a group of treatment agents from a package or replacement container of a treatment agent or group of treatment agents. The device furthermore has an evaluation apparatus (18) that, based on a detected code, ascertains which of the containers is or are to be replenished or replaced, and an indicating apparatus (4) which communicates to a user the ascertained container (6) or containers (6) that is or are to be replenished or replaced. The indicating apparatus may include a display (5) presenting a schematic image of the plurality of containers (6) with image(s) of each ascertained container being marked, and/or a light source (15) that illuminates each ascertained container.