  We find that mesoscopic conductance fluctuations in the quantum Hall regime
in silicon MOSFETs display simple and striking patterns. The fluctuations fall
into distinct groups which move along lines parallel to loci of integer filling
factor in the gate voltage-magnetic field plane. Also, a relationship appears
between the fluctuations on quantum Hall transitions and those found at low
densities in zero magnetic field. These phenomena are most naturally attributed
to charging effects. We argue that they are the first unambiguous manifestation
of interactions in dc transport in the integer quantum Hall effect.
