Some of the blind holes (6) between indentations (4) of a heating surface (3) contain lifting elements (7) which, after opening of a cover, release a microtitre plate (13) from the heating surface (3) and raise said microtitre plate about 2 to 3 mm, so that it can be removed without application of force. Each lifting element (7) consists of a coil spring (8) and a contact pin (9) made of, for example, PEEK which is inserted into said coil spring and presses with a round flat abutting surface (12) against the lower surface of the microtitre plate (13). The spring constant of the lifting element (7) is about 6 N/mm.