Abstract
A series of genetic crosses conducted to map the Ss serum variant with respect to the H—2 complex is described in detail. Three intra‐H—2 recombinants were detected. These crossovers, designated H—2al, H—2ol and H—2tl, position the Ss gene in the middle of the H—2 complex between the regions H—2K and H—2D. The production of eight new congenic resistant inbred strains is also described.