  The role of thermal conduction in regulating the thermal behavior of cooling
flows in galaxy clusters is reexamined. Recent investigations have shown that
the anisotropic Coulomb heat flux caused by a magnetic field in a dilute plasma
drives a dynamical instability. A long standing problem of cooling flow theory
has been to understand how thermal conduction can offset radiative core losses
without completely preventing them. In this Letter we propose that
magnetohydrodynamic turbulence driven by the heat flux instability regulates
field-line insulation and drives a reverse convective thermal flux, both of
which may mediate the stabilization of the cooling cores of hot clusters. This
model suggests that turbulent mixing should accompany strong thermal gradients
in cooling flows. This prediction seems to be supported by the spatial
distribution of metals in the central galaxies of clusters, which shows a much
stronger correlation with the ambient hot gas temperature gradient than with
the parent stellar population.
