At least one embodiment of the invention relates to an arrangement for thermocyclisation of a substance. At least one embodiment of the invention also relates to a method for the thermocyclisation of a substance, including: the controllable valves automatically close the PCR chamber after the test fluid has been introduced into the PCR-chamber, and the properties for the memory metal or bimetal elements are used for closing the valves when a predetermined temperature has been exceeded. As a result, the mechanical actuator, which is used to actuate the valves, is thermally coupled to the heating/cooling element in order to carry out the thermocyclisation.