  The production of antibaryons is calculated in a microscopic transport
approach employing multiple meson fusion reactions according to detailed
balance relations with respect to baryon-antibaryon annihilation. It is found
that the abundancies of antiprotons as observed from peripheral to central
collisions of $Pb + Pb$ at the SPS and $Au + Au$ at the AGS can approximately
be described on the basis of multiple interactions of 'formed' hadronic states
which drive the system to chemical equilibrium by flavor exchange or quark
rearrangement reactions.
