Studies on Immunizing Substances in Pneumococci

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Abstract
By comparison of Type I pneumococcus polysaccharides made by the calcium phosphate method and by the revised method of Heidelberger it was found that the acetyl group had no detectable significance for antigenicity as tested in white mice. This conclusion is based on a study of the 2 prepns. after treatment with (1) N NaOH at room temp. for 24 hours; (2) NH40H (sp. gr. = 0.89) for 24 hrs.; or (3) the same conc. of p-toluene sulfonic acid or o-phos-phoric acid as is used for hydrolysis of acetyl groups of organic compounds. After these various treatments, antigenicity of the final product was not significantly different from the original. The distillable acid after acid hydrolysis was identified by the use of the Kruger and Tschirch spot-test which gives a positive reaction in 0.05 cc. of 0.02 N acetic acid.