Abstract: Apparatus for taking a sample of liquid from each of a plurality of containers. Blood or similar settling liquids requiring continuous mixing are sampled for subsequent analysis from test tubes closed by rubber or plastic plugs. The test tubes are mounted along the periphery of a rotatable cassette, which is drivingly connected to a motor via gearing, a clutch and a brake, in such a manner, that the cassette rotates in order to maintain the liquids in the test tubes thoroughly mixed. The cassette is capable of stopping instantaneously when the clutch is disengaged. The cassette is locked in accurate position in front of a sampling needle by operation of the brake. The brake operates when a signal from an analysis instrument orders an electronic counter to determine the identity of the test tube to be selected and the cassette is stopped. Immediately, a pneumatic cylinder is operated to lower an arm fixing the selected test tube.