L FORMS FROM PNEUMOCOCCI,

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Abstract
L forms were obtained from pneumococci and propagated in transplants on soft horse serum agar media containing 10 to 20% sucrose and 0.1 to 0.3% MgSO4 The pneumococci developed as L forms only in a narrow range of penicillin concentration (0.1 to 0.3 units/ml) but the L forms once produced were not sensitive to high concentrations of penicillin. There was marked variability in results obtained with different strains. Growth was not improved in pour plates and did not occur in broth. The cocci could not be regained from the L forms. The L colonies of the pneumococcus differ in appearance from most L colonies, especially from those of the closely related streptococcus. The colonies contain large amounts of extracellular material and long chains of granules which are probably produced by mechanical stretching of the large bodies that contain the granules.