Crude membranes were obtained from L forms by allowing the cells to lyse in distilled water. The crude membranes were washed several times in distilled water, lyophilized, and extracted with phenol-acetic acid-water. The membrane proteins were separated electrophoretically in polyacrylamide gels run at pH 4.5. Electrophoretic patterns and densitometric tracings of the gels showed distinct, reproducible intergeneric differences among L forms of Proteus, Streptobacillus, Staphylococcus, and

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... ococcus. Differences within a genus could not be detected except between the group A streptococcal L forms and the one group D F-24 L form. This electrophoretic method offers possibilities for ready identification of L forms through the use of standard reference strains.