In a general investigation of the cultural requirements of the gonococcus it seemed well to test the influence of carbon dioxid at pressures approximating its tension in living tissue, that is, from 5-7 cm. Hg. For the purpose of this work a gram-negative coccus isolated from the pus of a case of gonorrhea in the male has usually been deemed a gonococcus without further attempt at specific identification. Slight irregularity of contour and more or less variation in size and staining intensity of the individuals, and the transparency or inconspicuousness of the young colonies have been regularly observed characteristics.