A. israelii strains carry common carbohydrate determinants. 2) Type strains NCTC 4860, ATCC 10048 and ATCC 12102 only carry the common determinants. 3) More recent isolates of A. israelii/1 can carry additional antigenic determinants in the cell wall. 4) These additional antigens can be separated by chromatography on Sephadex G-200.