More on cross-reactions of Pneumococci and Klebsiella.

Earlier studies are extended to the higher-numbered K-types of Klebsiella, several of which may now be fitted into the previously found groups. Additional correlations between chemical structure and serological specificity are given, not only among the higher K-types, but also for several which were previously uninterpretable because structures were not known at the time. K1, K5, K6, K7 and K56 are shown to form a related group, although the reasons for their cross-reactivities are not always the same.