  We investigate the physical properties of a two-component virialized
protogalaxy comprising a hot gas and cold clouds which are in pressure
equilibrium under the assumptions that the protogalaxy is both spherical and
homogeneous. Two conditions which we adopt are that the protogalaxy is in
virial equilibrium and that the cooling time is less than the dynamical time.
It is found that there exists an upper mass bound for such a two-component
  protogalaxy when the cloud mass is comparable to or greater than that of hot
gas. We also consider the stability of the cold cloud against the Jeans
instability and Kelvin-Helmholtz instability.
