Abstract
The agglutination, agglutinin absorp- tion, and precipitation reactions of 8 spp. of marine and "fresh water" luminous bacteria were studied. Cross agglutination results indicate an agglutinogenic specificity for Achromobacter fischeri, Photobacterium phosphoreum, Bacillus sepiae, and B. pierantonii. Cross reactions occur between A. harveyi and P. splendidum, between Vibrio albensis and V. phosphorescens, and between P. splendidum and B. sepiae. The V. albensis and V. phosphorescens cross agglutination expresses the only reciprocal relation. Luminous cell filtrates reveal an ability to produce both specific and group agglutinins. This suggests that the agglutinogenic factors derived from luminous cells are all present in their filtrates, and points to the classification of the latter as "complete" antigens. Cross precipitation expts. with both luminous-cell immune sera and filtrate immune sera exhibit marked group reactions. A distribution of common antigens or a possible dissociation of antigenic groups during the luminous-cell-filtrate transition is suggested. A specific antigen-antibody reaction which interferes with the luminescent system has not been noted.