  An intermediate nematic phase is proposed for the interpretation of recent
experimental results on phase biaxiality in bent-core nematics. The phase is
macroscopically uniaxial but consists of microscopic biaxial, and possibly
polar, domains. On applying an electric field the phase exhibits substantial
macroscopic biaxial ordering resulting from the collective alignment of the
domains. A phenomenological theory is developed for the molecular order in this
phase and for its transitions to purely uniaxial and to spontaneously biaxial
nematic phases.
