FLAGELLAR COMPONENTS SOMATIC COMPONENTS Specific Non-specific

Early studies of the agglutination reaction indicated that any bacterial cell contains several antigens. As a rule, these are in groupings with a specific antigenic group for each species. Topley and Wilson (1936) have ably summarized the development of techniques for antigenic analysis. White, Kaufmann and many of their contemporaries have applied intensive antigenic analysis in studies of the Salmonella group. This work has resulted in the recognition of a rather extensive list of antigenically related species. The addition of more types, variants or species, proceeds. Some of these types differ from others only to a slight degree. Because of this, it seems possible and logical that the very close similarity in certain cases is an indication of an evolutionary change which might possibly be induced under controlled labora-tory conditions. For example, Salmonella schottmulleri and Salmonella typhimurium are identical somatically; they differ only in two flagellar antigenic components. According to the Kaufmann-White schema, the antigenic composition of these two species is as follows