Test tube cassette for accommodating different tube sizes

A cassette for supporting a plurality of cylindrically-shaped containers of randomly varying diameters in spaced parallel relationship, said cassette comprising:

• a frame supporting a plurality of container-centering assemblies in side-by-side relationship, each of said container-centering assemblies being adapted to support a cylindrically-shaped container and to locate the longitudinal axis of such container at a desired location on said frame, each of said assemblies comprising (i) a housing defining a through opening for receiving a container, (ii) a pair of cooperating collar members slidably mounted on said frame for sliding movement toward and away from each other, said collar members having respective arcuate surfaces adapted to contact a side wall of a received container during the sliding movement thereof, and (iii) biasing means for biasing said collar members towards each other and towards engagement with the side wall of said container, whereby the respective arcuate surfaces of said collar members cooperate in supporting a container positioned therebetween.