COMPUTERIZED TESTING UNITS FOR LABORATORY USE-NAMELY, COMPUTERIZED UNITS DESIGNED TO DETECT, ENUMERATE, AND IN SOME INSTANCES DETERMINE THE ANTIBIOTIC SENSITIVITY OF MICROORGANISMS; SUPPLIES FOR SUCH UNITS-NAMELY, LABORATORY CASSETTES IN THE NATURE OF DISPOSABLE PLASTIC PLATES CONTAINING WELLS PREFILLED WITH FREEZE-DRIED MEDIA FOR USE IN TESTS MADE BY SUCH UNITS, AND SPECIMEN LOADERS FOR SUCH PLATES