STUDIES of the chemistry of cell walls of many Gram-positive bacteria have established that they possess distinctive properties; indeed, a number of the uncommon constituents of bacterial cells have been found to be localized in the walls, for example, αɛ-diaminopimelic acid, D-isomers of amino-acids, and the sugars D-arabinose and rhamnose1–3. Cell-wall peptides are composed of a small variety of amino-acids and as few as three or four different amino-acids may account for most of the peptide2,3. Amino-sugars form important constituents of the cell-wall muco-complex substances, and the amino-sugar isolated in a crystalline form by Strange and Dark4 has been shown to be a characteristic component of the walls of spores and Gram-positive bacteria2,4.