94 per cent of the phosphorus and 41 per cent of the glucosamine are removed by extraction of the cell walls with hot 5 per cent TCA, but significant amounts of the other constituents are not extracted by this procedure.

The residue after hot TCA extraction (mucopeptide) is susceptible to lysozyme whereas the intact cell walls are resistant.

Staphylococcus aureus cell walls are agglutinated by S. aureus antisera. Agglutination of the cell walls of one S. aureus strain is inhibited by absorption of antisera with cell walls of other S. aureus strains but not by absorption with S. albus cell walls.

The ribitol teichoic acid can be isolated from cold TCA extracts of the cell walls. This compound consists almost entirely of ribitol phosphate and glucosamine.

The isolated teichoic acid of strain NYH-6 is readily fixed to tanned sheep erythrocytes and these sensitized cells are agglutinated by S. aureus antisera. Cold TCA extracts of cell walls of other strains of S. aureus inhibit hemagglutination whereas extracts of S. albus walls do not.

Studies on the inhibition of both hemagglutination and precipitation indicate that the antigenic determinant of S. aureus NYH-6 teichoic acid is ß-N-acetylglucosamine.