Studies on the genus Shigella

Abstract

Summary 1. The precipitation reaction affords a simple and satisfactory method for studying existing variations in organisms of the Sh. paradysenteriae group. 2. The examination by the precipitation reaction of “old strains” of Type I–III, which have undergone mutation, indicate that they are similar to the standard laboratory Type VII (X). The standard laboratory cultures of Type VII and the type with dual antigen V–VII, proposed by Weil et al., give identical precipitation reactions. 3. Analyses of Type VIII (Y) and old mutated cultures of Type IV reveal them to be similar. 4. Evidence which tends to confirm Boyd's observations of mutation in the Flexner group has been presented.