From one strain of hemolytic streptococcus three forms were isolated, which produced three different degrees of hemolysis on the surface of blood agar in the presence of oxygen.

The original form was moderately hemolytic; the glossy variant was more hemolytic than the original form; and the third form, obtained by passing the original culture through mice, was non-hemolytic. Under anaerobic conditions all three forms were hemolytic. The non-hemolytic passage culture, in the presence of an ample supply of oxygen, not only destroyed its own hemolysin, which only appeared under anaerobic conditions, but was also able to destroy the hemolysin of other cultures of hemolytic streptococci.

It is possible that these observations may throw some light on experiments reported by a number of workers showing that Streptococcus hæmolyticus can be transmuted to Streptococcus viridans by animal passage.

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