NOTES genicity for mice between those cultures isolated from minor clinical involvements and those obtained from deep penetrating infections. Strains giving rise to smooth or rough colonies exhibited the same degree of virulence as mucoid strains. It was of interest to find that the bluegreen pigmented strains were generally more pathogenic for mice than were the nonpigmented varieties. On the other hand the brown-purple pigmented strains (total of three tested) were not pathogenic for mice

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... r the conditions of the test. These results emphasize the weak pathogenicity of strains isolated from human infections irrespective of severity of clinical involvement. It was not possible to predict the mouse pathogenicity of a strain on the basis of clinical origin and gross appearance.