Incubation period data of RIII, C57BL/6 and VM mice. Animals were inoculated with various BSE/scrapie mixtures and the BSE and scrapie sources that were used to produce the mixtures. In the mixtures only the percentage of BSE is indicated; the remaining reflects scrapie percentage. Circles indicate individual mice, vertical lines indicate the mean of the group. RIII, red; C57BL/6, black; VM, green.