1. The meningococcus polysaccharide reacts with a broad precipitable carbohydrate antibody in common with those of B. anthracis, B. subtilis, B. proteus and B. mesentericus.
2. The anthrax and proteus polysaccharides are specific in the higher dilutions of serum.
3. Antianthrax serum contains two different polysaccharide precipitable antibodies, one specific and the other non-specific.
4. Agglutinins have no relation to the carbohydrate precipitable substance, specific or non-specific.
5. An immunological method is given for the study of the probable chemical relation or similarity of polysaccharides of different bacteria similar to that given by Heidelberger, Goebel and Avery from a strain of Friedländer bacillus and Pneumococcus Type II.