Capsulated transformants producing type II polysaccharide have been obtained by reactions between a number of R mutants of type II pneumococcus.

All the IIR strains except II-R36 yielded extracts which transformed 2 VIIIR strains to VIIIS. Two of the IIR strains were transformed to VIIIS by an extract of 1 VIIIR strain.

The most striking result was the production of both IIS and VIIIS transformants by the action of extracts of both VIIIR strains applied to cells of II-RB. This suggests that the determination of capsular type in pneumococcus does not depend on single allelomorphic genes; it seems more likely that a number of genes may be required to determine type specificity, and that some genes may be common to different types, possibly in connection with common biochemical pathways for some stages of polysaccharide synthesis.

This is further indicated by the finding that extracts of capsulated strains of each of the types I, II, III, VII, VIII, XIV, and XVIII are capable of giving IIS transformants with 1 or more of the IIR strains in addition to the expected donor-type transformants.

Strain II-R36 was transformed by extracts of all S types except type VII, but the only transformants found were of the donor type. It appears that II-R36 may have multiple genetic deficiencies for type II capsulation, possibly in the form of a deletion. This may be the case also with IIIS strains since only IIIS transformants were found when IIIS extract was applied to any of the IIR strains.

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