Immunodiffusion plates, stained with amido black. (Upper picture) left well = clover strain; right well = cymbidium strain; upper well = antiserum to cymbidium strain. Shows spur formation between clover and cymbidium strains, and single lines of precipitation.
(Lower picture) left well = clover strain, antigen A only; right well = clover strain, antigens A + B; upper well = antiserum to clover strain with A + B components. Note the two lines of precipitation for A and B antigens respectively, with the latter (nearer to the antigen well) unrelated to antigen A. All antigens in partially purified preparations.