Method for reducing liquid evaporation from wells of a microplate, comprising: a) providing the microplate with a plurality of wells, b) adding a sample to at least one of the wells of the microplate, c) inserting the microplate or an incubation cassette equipped with the microplate into a microplate reader, d) injecting a liquid into a liquid reservoir provided in the microplate and/or the incubation cassette, e) performing measurements on the samples in the respective wells, f) optically measuring a liquid level in the liquid reservoir of the microplate and/or the incubation cassette through an essentially transparent section of the liquid reservoir of the microplate and/or the liquid reservoir of the incubation cassette, g) re-injecting the liquid into the liquid reservoir of the microplate and/or into the liquid reservoir of the incubation cassette when the liquid level falls below a predetermined threshold, h) repeating steps e) to g) until a predetermined number of measurement cycles is reached, i) withdrawing the microplate or the incubation cassette equipped with the microplate from the microplate reader, characterized in that the liquid reservoir is provided between the wells and is bounded by a wall of the microplate and is formed to accommodate a liquid, wherein the microplate is provided with the liquid reservoir and comprises the at least one transparent section, and/or that the incubation cassette comprises a frame for receiving a microplate with wells, wherein the frame comprises a central first opening surrounded by an inner wall, the dimensions of which are designed for inserting a microplate, and wherein the frame comprises an outer wall extending substantially parallel to the inner wall and which adjoins the inner wall via an intermediate bottom, wherein the liquid reservoir is formed by the two walls (6, 8) and the intermediate bottom as a liquid reservoir surrounding the first central opening for receiving a liquid, wherein at least one section (6,8,14) of the incubation cassette forming the liquid reservoir is provided at least sectionally with the at least one transparent section. a) providing the microplate with a plurality of wells, b) adding a sample to at least one of the wells of the microplate, c) inserting the microplate or an incubation cassette equipped with the microplate into a microplate reader, d) injecting a liquid into a liquid reservoir provided in the microplate and/or the incubation cassette, e) performing measurements on the samples in the respective wells, f) optically measuring a liquid level in the liquid reservoir of the microplate and/or the incubation cassette through an essentially transparent section of the liquid reservoir of the microplate and/or the liquid reservoir of the incubation cassette, g) re-injecting the liquid into the liquid reservoir of the microplate and/or into the liquid reservoir of the incubation cassette when the liquid level falls below a predetermined threshold, h) repeating steps e) to g) until a predetermined number of measurement cycles is reached, i) withdrawing the microplate or the incubation cassette equipped with the microplate from the microplate reader, that the liquid reservoir is provided between the wells and is bounded by a wall of the microplate and is formed to accommodate a liquid, wherein the microplate is provided with the liquid reservoir and comprises the at least one transparent section, and/or that the incubation cassette comprises a frame for receiving a microplate with wells, wherein the frame comprises a central first opening surrounded by an inner wall, the dimensions of which are designed for inserting a microplate, and wherein the frame comprises an outer wall extending substantially parallel to the inner wall and which adjoins the inner wall via an intermediate bottom, wherein the liquid reservoir is formed by the two walls (6, 8) and the intermediate bottom as a liquid reservoir surrounding the first central opening for receiving a liquid, wherein at least one section (6,8,14) of the incubation cassette forming the liquid reservoir is provided at least sectionally with the at least one transparent section.