Abstract: Samples of blood from hundreds of patients are held in test tubes mounted in twenty endless chains of the same number of links, each chain being mounted on a chain-holder keyed so as to be insertable for mounting on only one sector of a rotary disk. A locking member by which the chain is closed must occupy the inside position when the chain is mounted. Since each sample then has a distinctive machine address, program control can then drive the machine so that all the individual samples requiring transfer of a portion for a particular analytical procedure are successively presented to a pipette transfer device, chain by chain, with rotation of all chains so that the chain presented to the pipette apparatus will present in succession only those individual samples requiring the particular analysis samples for the next analytical procedure.