  We interpret the phase structure of hadronic matter in terms of the basic
dynamical and geometrical features of hadrons. Increasing the density of
constituents of finite spatial extension, by increasing the temperature T or
the baryochemical potential mu, eventually "fills the box" and eliminates the
physical vacuum. We determine the corresponding transition as function of T and
mu through percolation theory. At low baryon density, this means a fusion of
overlapping mesonic bags to one large bag, while at high baryon density, hard
core repulsion restricts the spatial mobility of baryons. As a consequence,
there are two distinct limiting regimes for hadronic matter. We compare our
results to those from effective chiral model studies.
