  A preon-based composite model of the fundamental fermions is discussed, in
which the fermions are bound states of smaller entities -- primitive charges
(preons). The preon is regarded as a dislocation in a dual 3-dimensional
manifold -- a topological object with no properties, save its unit mass and
unit charge. It is shown that the dualism of this manifold gives rise to a
hierarchy of complex structures resembling by their properties three families
of the fundamental fermions. Although just a scheme for building a model of
elementary particles, this description yields a quantitative explanation of
many observable particle properties, including their masses.
