  We show that the gas in growing density perturbations is vulnerable to the
influence of winds outflowing from nearby collapsed galaxies that have already
formed stars. This suggests that the formation of nearby galaxies with masses
less than 10^9 solar masses is likely to be suppressed, irrespective of the
details of galaxy formation. An impinging wind may shock heat the gas of a
nearby perturbation to above the virial temperature, thereby mechanically
evaporating the gas, or the baryons may be stripped from the perturbation
entirely if they are accelerated to above the escape velocity. We show that
baryonic stripping is the most effective of these two processes, because
shock-heated clouds that are too large to be stripped are able to radiatively
cool within a sound-crossing time, limiting evaporation. The intergalactic
medium temperatures and star-formation rates required for outflows to have a
significant influence on the formation of low-mass galaxies are consistent with
current observations, but may soon be examined directly via associated
distortions in the cosmic microwave background, and with near-infrared
observations from the Next Generation Space Telescope, which may detect the
supernovae from early-forming stars.
