1. Smooth, round, shiny, non-granular, and non-spreading colonies have been observed in cultures of virulent tubercle bacilli freshly isolated from eight human sources other than sputum. The classification of six of these strains as of human type was established by inoculation into rabbits and guinea pigs.
2. The 3 per cent NaOH or 6 per cent H2SO4 frequently used in the isolation of tubercle bacilli are definitely unfavorable to the development of smooth colonies.
3. It was observed that smooth colonies are produced in greater number when the pH of the medium (Corper's egg yolk-glycerine) is adjusted to a point near to but slightly on the acid side of neutral.