A study was made of cross-reactions of synthetic polyglucose and of numerous plant and bacterial gums in an antityphoid and an antiparatyphoid B horse serum. The observed differences permit conclusions to be drawn regarding certain of the linkages likely to be found in the fine structures of each of the corresponding Salmonella polysaccharides:—
1. Cross-reactions of the antityphoid serum with the specific polysaccharide of Type II pneumococcus and with tamarind seed polysaccharide, glycogen and synthetic polyglucose indicate that the acetic acid-degraded O-polysaccharide of S. typhi, strain O 901, may contain part, at least, of its glucose as 1,4,6-branch points or in 1,6-linkage, perhaps adjacent to a terminal, non-reducing, galactopyranose unit.
2. Cross-reactions of both antisera with arabogalactans point to the existence of (probably ß-) 1,3-, 1,6-, and/or 1,3,6-linkages of galactose in both the typhoid and paratyphoid B polysaccharides.
3. The differential reactivities of the galactomannans and yeast mannan suggest that the mannose in the typhoid polysaccharide is linked 1,2- or 1,3- with possible non-reducing mannopyranose end groups attached 1,6-. In the paratyphoid B polysaccharide the linkages are probably galacto-oligomannose 1,4-, or 1,4,6-, or the corresponding linkages of mannose alone.