  We introduce a model system of stochastic entities, called 'rowers' which
include some essentialities of the behavior of real cilia. We introduce and
discuss the problem of symmetry breaking for these objects and its connection
with the onset of macroscopic, directed flow in the fluid. We perform a mean
field-like calculation showing that hydrodynamic interaction may provide for
the symmetry breaking mechanism and the onset of fluid flow. Finally, we
discuss the problem of the metachronal wave in a stochastic context.
