  The electromagnetic pion form-factor is calculated in a Bethe-Salpeter
approach which accounts for pion rescattering. In the scattering kernel the
pion-pion contact interaction from lowest-order chiral perturbation theory is
considered together with an optional vector meson in the s-channel.
Correspondingly the virtual photon couples to a two-pion state and optionally
to the vector meson. It is shown that for reasonable ranges of input parameters
the experimentally observed pion form-factor cannot be described by the
iterated pion-pion contact interaction alone, i.e. without an elementary vector
meson. The inclusion of an elementary vector meson allows for an excellent
description. This completes a recent study (``Information on the structure of
the a_1 from tau decay'') where it has been shown that the a_1 meson can be
well understood as a rescattering process of rho meson and pion. Here it is
demonstrated that within the same formalism the rho meson cannot be understood
as a pion-pion rescattering process. This suggests that the chiral partners a_1
and rho are not only different in mass, but also different in nature.
