SUMMARY

A study has been made of 607 cultures of Gram-positive and catalase-positive cocci received from workers and collections in different parts of the world. These cultures were examined for a wide range of morphological and physiological characters and representative cultures were further studied to determine the chemical constituents of the organisms. Five hundred and sixty-four of the cultures received were aerobic members of the Micrococcaceae, and of these 96 % were classified in the author’s groups and subgroups; a further subgroup was, however, introduced to accommodate the not previously studied pink-pigmented micrococci. It appears that the Gram-positive and catalase-positive cocci are best separated intq,the genus Staphylococcus and the genus Micrococcus on the ability of members of Staphylococcus to grow and produce acid from glucose anaero-bically; six subgroups of staphylococci were recognized and eight of micrococci. The relationship of named species, p u p s and subgroups to the author’s classification was examined; several species and groups of micro-cocci had been incorrectly classified. Thus, M. denitrijcaas, M. halodenitri-$cans and M. radiodurans possess characters which suggest that they should be reclassified with the Gram-negative genera and that Abd-El-Malek and Gibson’s group IIIB should be classified with the Gram-positive microbacteria