"Gauze No. 1" medium was used as a culture medium for the isolation of soil actinomycetes with the addition of 100 ppm K₂Cr₂O₇. The modified medium gives larger colony numbers and more kinds of species with distinguishable characteristics in comparison with the original method, but the growth of bacteria and fungi have been largely inhibited. Using this medium, the same species may 'be grouped into species group, and it is possible to identify the names of species group directly on the plate.