1. Random selections of the sera of trainees injected 2 months previously with the specific polysaccharides of Types I, II, V, and VII pneumococci contained quantities of antibody to Types I, II, and VII sufficient to account for the favorable results of the immunization procedure.
2. As in earlier studies, the levels of the antibody for the C polysaccharide remained relatively constant before and after the injections.
3. The serum from the preliminary bleedings often contained antibody to the Type VII polysaccharide. This remained relatively constant in a control group injected with saline.