  We re-investigate Adler's PCAC relation in the presence of an external
electromagnetic field within the framework of QCD coupled to external fields.
We discuss pion electroproduction within a tree-level approximation to chiral
perturbation theory and explicitly verify a chiral Ward identity referred to as
the Adler-Gilman relation. We critically examine soft-momentum techniques and
point out how inadmissable approximations may lead to results incompatible with
chiral symmetry. As a result we confirm that threshold pion electroproduction
is indeed a tool to obtain information on the axial form factor of the nucleon.
