  We consider the effects of a two-form field on the late-time dynamics of
brane gas cosmologies. Assuming thermal equilibrium of winding states, we find
that the presence of a form field allows a late stage of expansion of the
Universe even when the winding degrees of freedom decay into a pressureless gas
of string loops. Finally, we suggest to understand the dimensionality of the
Universe not as a result of the thermal equilibrium condition but rather as a
consequence of the symmetries of the geometry.
