Although members of the species Microtus agrestis are induced ovulators (Austin, 1957; Breed, 1967), ovulation may be induced by stimuli other than those associated with mating, e.g. when females are separated from adult males by wire mesh (Milligan, 1974). Tactile contact between the sexes is not necessary for this ovulatory response as ovulation still occurred when two barriers of mesh, 2\m=....