Abstract: The invention concerns a thermostated block for laboratory thermostats and comprising wells at a wells side to receive and make large-area contact with the parts of vials filled with sample liquids and comprising at least two heat regulating devices contacting the thermostated block in thermally conducting manner to generate different temperatures at different sites of the thermostated block, said block being characterized in that the heat regulating devices are in large-area contact with adjoining zones of the contact side opposite the wells side of the thermostated block.