  We calculate the elastic field mediated interaction between macroscopic
particles in a columnar hexagonal phase. The interaction is found to be
long-ranged and non-central, with both attractive and repulsive parts. We show
how the interaction modifies the particle correlations and the column
fluctuations. We also calculate the interaction of particles with the
topological defects of the columnar phase. The particle-defect interaction
reduces the mobility of the defects.
