Isolation of L Type Cultures from lostridia.

L type cultures have been isolated from a strain of Clostridium tetani with the help of penicillin. Similar cultures were obtained from a freshly isolated unidentified Clostridium when the area surrounding a 2-day-old agar culture was reinoculated with the same strain. The metabolic products diffusing from old culture inhibited growth and transformed the bacilli into L forms. The L type cultures obtained are similar in appearance and morphology to those isolated previously from a Gram positive spore-bearing bacillus. They differ from the L forms of Gram negative bacilli inasmuch as they grow better in the absence rather than the presence of animal serum and have a tendency to form large spreading colonies increasing in size for several months.