IMPROVED METHODS FOR THE PREPARATION OF THE SPECIFIC POLYSACCHARIDES OF PNEUMOCOCCUS.

The specific polysaccharides of Types I and V pneumococcus give sharp equivalence zones and show maximal precipitation with homologous rabbit antisera only when carefully prepared from cultures which have not been neutralized with alkali. The precipitating power of S V toward homologous rabbit antiserum falls off in 0.1 N NaOH even more rapidly than that of S I, dropping to 7 per cent of the original value in 6 days at room temperature. The alkaline solution develops a large absorption peak at 270 mmicro. Directions are given for the preparation of S VII and S XII.