  It has recently been conjectured that the type IIA string theory compactified
on K3 and the heterotic string theory compactified on a four dimensional torus
describe identical string theories. The fundamental heterotic string can be
regarded as a non-singular soliton solution of the type IIA string theory with
a semi-infinite throat. We show that this solution admits 24 parameter
non-singular deformation describing a fundamental heterotic string carrying
electric charge and current. The charge is generated due to the coupling of the
gauge fields to the anti-symmetric tensor field, and not to an explicit source
term. This clarifies how soliton solutions carrying charge under the
Ramond-Ramond fields can be constructed in the type IIA theory, and provides
further support to the string string duality conjecture. Similarly, the
fundamental type IIA string can be regarded as a non-singular solution of the
heterotic string theory with a semi-infinite throat, but this solution does not
admit any deformation representing charged string. This is also consistent with
the expectation that a fundamental type IIA string does not carry any charge
that couples to the fields originating in the Ramond-Ramond sector.
