  In a recent paper, based on the Skyrme model with the Wess-Zumino-Witten term
including electromagnetism, Eto et al. pointed out an intriguing possibility
that the Gell-Mann-Nishijima relation is corrected under the presence of
back-ground electromagnetic fields, thereby being led to the conclusion that
even a neutron acquires non-zero net charge in external magnetic fields. We
point out that this remarkable conclusion is inseparably connected with an
unwelcome feature of the gauged Wess-Zumino-Witten action, i.e. the
non-conservation of source current of Maxwell equation.
