Agglutination of motile salmonellas by acridines.

Genetic studies of the determination of Salmonella flagella have suggested that the alternative antigenic phases correspond to two distinct homology groups, i.e., to factors at two distinct genetic loci, one for phase 1 ("specific phase"), and one for phase 2 ("group phase") (Lederberg and Edwards, 1953). It has, however, been generally understood that the two phases were equivalent to one another in all respects save their detailed antigenic structure and thus would give no hint of such a dual determination (Stocker, 1949). Sertic and Boulgakov (1936a, b) had, however, reported slide agglutination of smooth phase 2 cultures by acriflavine, while phase 1 did not react. We have sought, therefore, to confirm this generally overlooked observation and to look for any further clues that might bear on the reversible differentiation of the two loci which control flagellar phase variation (Lederberg, 1954).