  Let G be a finite group. We show that the Bass Nil-groups $NK_n(RG)$, $n \in
Z$, are generated from the p-subgroups of G by induction maps, certain twisting
maps depending on elements in the centralizers of the p-subgroups, and the
Verschiebung homomorphisms. As a consequence, the groups $NK_n(RG)$ are
generated by induction from elementary subgroups. For $NK_0(ZG)$ we get an
improved estimate of the torsion exponent.
