Virtual photon structure functions and the parton content of the electron

We point out that in processes involving the parton content of the photon the usual effective photon approximation should be modified. The reason is that the parton content of virtual photons is logarithmically suppressed compared to real photons. We describe this suppression using several simple, physically motivated Ansa$uml—tze. Although the parton content of the electron in general no longer factorizes into an electron flux function and a photon structure function, it can still be expressed as a single integral. Numerical examples are given for the ${\mathit{e}}^{+}$ ${\mathit{e}}^{\mathrm{-}}$ collider TRISTAN as well as the ep collider HERA.