Abstract
Isolated cell wall membranes of Escherichia coli and Salmonella para-typhosus B (normal forms and O-antigen-free R-variants) still show the serologicalO- or R-characteristics of their homologous cells as do also the media used in their preparation. These antigens are also autolysis- and trypsin-resistant. However, the R-antigen, which is present and assumed to be deeper-lying, disappears. According to the results of serological studies using lipopolysaccharide and protein fractions quantitatively extracted from the cell, the isolated cell wall membranes of normal and variant forms must contain protein and lipopolysaccharide fractions common to both as well as specific for each cell form. Saturation tests show that both membranes in addition to O- and R-antigen complexes which serologically characterize them and their homologous cell forms have other (membrane specific) antigen receptors.