  We study the statistical properties of the cosmological 21 cm signal from
both the intergalactic medium (IGM) and minihalos, using a reionization
simulation that includes a self--consistent treatment of minihalo
photoevaporation. We consider two models for minihalo formation and three
typical thermal states of the IGM -- heating purely by ionization, heating from
both ionizing and $\rm Ly\alpha$ photons, and a maximal "strong heating" model.
We find that the signal from the IGM is almost always dominant over that from
minihalos. In our calculation, the differential brightness temperature,
${\delta}T_b,$ of minihalos is never larger than 2 mK. Although there are
indeed some differences in the signals from the minihalos and from the IGM,
even with the planned generation of radio telescopes it will be unfeasible to
detect them. However, minihalos significantly affect the ionization state of
the IGM and the corresponding 21 cm flux.

Cosmology and Nongalactic Astrophysics