  It is shown that hadron abundances in high energy e+e-, pp and p{\bar p}
collisions, calculated by assuming that particles originate in hadron gas
fireballs at thermal and partial chemical equilibrium, are in very good
agreement with the data. The freeze-out temperature of the hadron gas fireballs
turns out to be nearly constant over a large center of mass energy range and
not dependent on the initial colliding system. The only deviation from chemical
equilibrium resides in the incomplete strangeness phase space saturation.
Preliminary results of an analysis of hadron abundances in S+S and S+Ag heavy
ion collisions are presented.
