  We study a thermodynamically consistent implementation of the nucleon volume
in the mean field theory, and find that this volume has large consequences on
the properties of hadronic matter under extreme conditions such as in
astrophysical objects and high energy heavy-ion collisions. It is shown that we
can reproduce the critical temperature $T_{c}\simeq 200$ MeV predicted by
lattice QCD calculations for the phase transition from hadronic matter to
quark-gluon plasma, by using parameters which are adjusted to fit all empirical
data for normal nuclear matter.
