  A model of multiparticle production in hadronic collisions at
ultra-relativistic energies, based on the assumption of independent string
fragmentation, reproduces the rapidity spectra of $\Lambda$ and $\bar{\Lambda}$
in sulphur-sulphur collisions reported by the NA35 Collaboration. This is
achieved after a reconsideration of the intermediate multi-string states and
the structure of the diquarks. Nuclear stopping power is also studied through
the computation of the $p-\bar{p}$ rapidity spectra.
