Abstract: A plastic tubular member, open longitudinally along one side, is compartmented across its width to receive a plurality of media for supporting different bacteria cultures; and is equipped with an inoculating wire which extends axially along the tubular member through aligned intramural openings between the compartments. To prevent contamination between compartments, and maintain them in a sterile condition before introduction of bacteria cultures, the intramural openings are sealed with drops of wax in a two-step process. In a first step, the inoculating wire, which extends beyond the ends of the tubular member, serves to support the tubular member with the compartment openings directed downward over a vat of molten wax. A reciprocating comb having a plurality of prongs is mechanically moved from a lower position in which it is immersed in the molten wax, to an upper position, in which the prongs engage the compartment openings.