Solutions of all of the C. P. sucrose reagents of American manufacture that were tested gave reactions with Type II antipneumococcus serum. The capacity of that antiserum to react with sucrose solutions was removed by absorption with the homologous pneumococci or with Leuconostoc mesenteroides. The serological reactivity was due not to sucrose itself but to accompanying substances that could be removed by precipitation with a proper concentration of alcohol or by treatment with activated carbon. Although Type II antipneumococcus serum was used to detect its presence the reactive material found in the sucrose can be considered to be only related and not identical with antigens of Type II pneumococci.