  We propose that at low energy four dimensional bosonic strings may form bound
states where they become bundled together much like the filaments in a cable.
We inspect the properties of these bundles in terms of their extrinsic
geometry. This involves both torsion and curvature contributions, and leads to
four dimensional field theories where the bundles appear as closed knotted
solitons. Field theories that allow for this interpretation include the Faddeev
model, the Skyrme model, the Yang-Mills theory, and a Hartree-type field theory
model of a two-component plasma.
