The capsular polysaccharide of Diplococctw pneumoniae Type XII contains residues of D-glucose and D-galactose in a molar ratio of 2:l. The methylated polysaccharide yielded upon hydrolysis 2,3,4,6-tetraand 3,4,6-tri-O-methyl-D-glucose and 2,3,4,6-tetra-0-methyl-D-galactose as the only neutral methyl sugars. Periodate oxidation of the polysaccharide resulted in destruction of all neutral sugars ...