  We construct a locally supersymmetric action for the scalar particle, and
study its relation with the usual reparametrization invariant action. The
mechanisms at work are similar to those employed in the embedding of the
bosonic string into the fermionic one, originally due to Berkovits and Vafa in
their search for a universal string. The simpler algebraic structure present in
the particle case provides us with a guide on how to prove in a simple way,
without the need of fixing the superconformal gauge, that the supersymmetric
formulation of the bosonic string is equivalent to the usual one, where
reparametrization invariance is the only world-sheet gauge symmetry.
