CROSS-REACTIONS OF PNEUMOCOCCAL TYPES. QUANTITATIVE STUDIES WITH THE CAPSULAR POLYSACCHARIDES.

Data are given on the amounts of antibody nitrogen precipitated in the crossreactions, often reciprocal, of the specific capsular polysaccharides of the pneumococcal type pairs II and XX, II and XIX, VII and XIV, VII and XVIII, VII and XIX, VIII and XVIII, VIII and XIX, X and XIV, and X and XX. Since little is known of the fine structures of the polysaccharides of Types VII, X, XIX, and XX, rigorous correlations between chemical structure and specificity can not be made, but several tentative conclusions are drawn.