Abstract
SUMMARY: Continuous, cell-shaped mucopolymer layers were isolated from cell walls of some unstable and stable L-forms of Proteus mirabilis. The chemical compositions of these non-rigid mucopolymers and of normal rigid mucopolymer basal-structures of rod-shaped Proteus bacteria were very similar. Electron microscopy showed that the protein and mucopolymer of the complex "rigid layers" were organized differently in cell walls of rods and L-form cells. The results suggest that the rigid-layer protein plays a role in the morphogenesis of the mucopolymer.