Serological Reactions of L Type Cultures Isolated from Proteus. ∗ †

Summary

The serological properties of 3 Proteus strains and the L forms isolated from them have been studied. The L antigens were agglutinated both by the bacillary and L immune rabbit sera in a relatively low titre and agglutination occurred in large loose flocci. Clear filtrates of L emulsions gave a good precipitation. The reactions of 2 L type cultures were strain specific. A marked common reaction was present between the bacillary and L forms of 2 strains both in the production of antibodies and in the in vitro tests. There was only a slight overlapping in the reactions of the L forms and of the bacilli in the third strain. The similarity of the serological reactions of the bacillary and L forms of 2 Proteus strains is further evidence for the genetical identity of the L forms and the bacilli. The nature of the serological dissimilarity between the bacillary and L forms of one strain, apparent both in in vitro tests and in antibody production, can not be interpreted at present.