Abstract: A luminescence measuring system comprises an apparatus for supplying samples located in separate test tubes. In the measuring chamber of a luminometer, the samples are in turn presented to a light detector, such as photomultiplier. Two mutually displaceable components, which are cup-shaped and fit into one another with the cup bottoms facing outwards, define the measuring chamber. The component shells are provided with holes which can be aligned by relative displacement of the components so as to admit the test tube into the luminometer and the measuring chamber and subsequently to discharge it therefrom under the action of gravity. The test tubes are conveyed to the luminometer by a sleeve-chain conveyor having a bottom with a through hole.