Abstract
1. Group variants devoid of type antigen, described in the previous section, provide material for ascertaining the various components of the antigen in the mannitol-fermenting dysentery bacilli.2. Flexner Y, as defined by Andrewes and Inman, is not a valid type. The strains which are regarded as being of this type, such as Y Hiss and Russell and Y Lentz, are old strains which have lost their type antigen and possess only group antigen. The reason why many newly isolated strains are identified as Y is because the antiserums used for their recognition contain more group than type agglutinin.3. The four Flexner types V, W, X, and Z, each possess a distinctive type antigen and share a complex group antigen. They do not, as suggested by Andrewes and Inman, possess minor quantities of each other's type antigen.4. 103, P 119, and the 88-Newcastle-Manchester series have also distinctive type antigens, and share the same group antigen with V, W, X, and Z.5. It is considered that the existing Flexner group should be extended to include all organisms which have a type-specific antigen and share this common group antigen. The three types in (4) should therefore be placed in the group and named accordingly.6. Six types which have the biochemical reactions of the Flexner group, and which have individual type antigens but no Flexner group antigen, are provisionally placed in a separate loose group.