  We derive the zero mode solutions for a Majorana fermion in the background of
a cosmic string and contrast it with the zero mode solution for a (neutral)
Dirac fermion. A Majorana zero mode carries no vector or axial charge, and it
cannot be bosonised. We study the implications for vorton formation and
stability. In the massless limit stability of the zero mode is guaranteed by
energy-momentum conservation. However, zero modes obtain an effective mass on
string loops. It is found that the conditions under which current formation can
be effective are exactly those for which zero mode decay is most likely to
occur.
