A microplate reader, at least comprising: a) a measurement chamber; b) an action source, which is designed to produce an interaction with biological structures in wells of a microplate and to induce or generate a measurable signal; c) a measuring device, which is designed to detect a signal, which was emitted by biological structures in wells of a microplate or which was induced or generated by the action source in or on biological structures in wells of a microplate; wherein the measuring device defines an optical axis; d) a transportation support, which is at least partially extendable from the measurement chamber, and which is designed for positioning wells of a microplate in relation to the optical axis of the measuring device of the microplate reader, by the transportation support being designed as movable in at least one direction inside the measurement chamber; and e) a controller, which is designed for controlling the action source, the measuring device, and the movements of the transportation support of the microplate reader; characterized in that the microplate reader comprises an incubation device for reducing a liquid evaporation from wells of a microplate, wherein: (i) the incubation device comprises a frame for accommodating a microplate comprising wells having well bottoms; (ii) the frame comprises a first opening, which is enclosed by an inner wall, and the dimensions of which are designed for inserting a microplate; and (iii) the frame comprises an outer wall which extends substantially parallel to the inner wall, and which adjoins the inner wall via an intermediate bottom, so that a channel enclosing the first opening for accommodating a liquid adapted to the content of the microplate wells is formed by the two walls (6, 9) and the intermediate bottom; that the incubation device comprises a bearing surface comprising a second opening, wherein this bearing surface is formed on the inner wall and is formed to bear an inserted microplate, and wherein as a consequence of the second opening, all bottoms of the wells of a microplate inserted into the incubation device are freely accessible through the second opening; that the transportation support of the microplate reader comprises at least one supporting surface, which is designed for depositing or raising the incubation device, comprising a read opening; and that the read opening of the transportation support is adapted in its size and position to the second opening of the frame of the incubation device in such a way that all bottoms of the wells of a microplate inserted into the incubation device are freely accessible through the read opening. a) a measurement chamber; b) an action source, which is designed to produce an interaction with biological structures in wells of a microplate and to induce or generate a measurable signal; c) a measuring device, which is designed to detect a signal, which was emitted by biological structures in wells of a microplate or which was induced or generated by the action source in or on biological structures in wells of a microplate; wherein the measuring device defines an optical axis; d) a transportation support, which is at least partially extendable from the measurement chamber, and which is designed for positioning wells of a microplate in relation to the optical axis of the measuring device of the microplate reader, by the transportation support being designed as movable in at least one direction inside the measurement chamber; and e) a controller, which is designed for controlling the action source, the measuring device, and the movements of the transportation support of the microplate reader; (i) the incubation device comprises a frame for accommodating a microplate comprising wells having well bottoms; (ii) the frame comprises a first opening, which is enclosed by an inner wall, and the dimensions of which are designed for inserting a microplate; and (iii) the frame comprises an outer wall which extends substantially parallel to the inner wall, and which adjoins the inner wall via an intermediate bottom, so that a channel enclosing the first opening for accommodating a liquid adapted to the content of the microplate wells is formed by the two walls (6, 9) and the intermediate bottom;