  Recently the concept of the pion cloud in the nucleon turned out to be
successful in understanding the Gottfried sum rule violation observed by the
New Muon Collaboration and the Drell--Yan asymmetry measured in NA51 at CERN.
We propose a further possibility to test this concept at HERA through the
analysis of the structure of deep inelastic scattering (DIS) events induced by
pion--exchange. Momentum and energy distributions of outgoing nucleons as well
as rapidity and multiplicity distributions are investigated using Monte Carlo
simulations. Most observables cannot distinguish this process from ordinary
DIS, but in the energy distribution of final neutrons we find a significantly
different prediction from the pion cloud model. Forward neutron calorimeters
will be essential to test the concept of pions in the nucleon.
