Virus of Spontaneous Encephalomyelitis Found in Intestines of Normal Wild Gray Mice

(1) Wild gray house-mice are as susceptible to intracerebral introduction of Theiler's virus as are albino mice. (2) Apparently normal gray mice trapped in an animal house in which almost all adult albino mice are carriers of Theiler's virus, reveal this virus in their intestines and not in their brains. (3) The virus is indistinguishable from that obtained from the intestines of normal albino mice. (4) The number of gray mice shown to be carriers of Theiler's virus, while considerable, appears to be lower than that of carriers found among the albino strain.