Abstract: To permit light-weight construction of a rotor of a centrifuge holding sample carriers adapted to retain probes, the rotor is formed at its outer circumference with a sleeve of at least partly fiber-reinforced plastic. The holders are secured to the rotor and movable in guide means so that when swinging outwardly under centrifugal force, they can abut against the outer sleeve, preferably with interposition of a segmental element to provide for large area contact, the fiber-reinforced plastic sleeve, being continuous and circular, absorbing centrifugal forces.

Abstract: The centrifuge rotor is formed with a central chamber and two peripheral annular chambers concentric therewith; an annular bag including ring-shaped compartments, made of flexible material, and with communicating ducts are placed into the three chambers, the central chamber additionally being big enough to accommodate a holder for treatment liquid and for the reception of treated biological fluid, after centrifuging and treatment; valves, which may be centrifugally or otherwise operated, control flow between the central bag compartment in the central chamber of treatment liquid to the intermediate bag compartment in the intermediate chamber, and flow from the intermediate compartment of used treatment fluid to the outer peripheral compartment. A dimensionally stable, bulged, disk-shaped body is located in the compartments to assure that the bag retains its shape.