  The strikingly different high energy behaviours of real photoabsorption
cross-sections with Q^2 = 0 and the low x proton structure function at large
Q^2 are studied from a laboratory frame viewpoint, in which the x and Q^2
dependence reflects the space-time structure of the interaction. This is done
using a simple model which incorporates hadron dominance, but attributes the
striking enhancement observed at HERA at very low x and high Q^2 to
contributions from heavy long-lived fluctuations of the incoming photon.
Earlier published predictions of the model for the then unknown behaviour of
the structure function at small x and intermediate Q^2 are shown to be
strikingly confirmed by recent experimental data. A simultaneous analysis of
real photoabsorption data and structure function data for 0 <= x < 0.1 and 0 <=
Q^2 <= 15 GeV^2 is then reported. An excellent fit is obtained, with all
parameters in the restricted ranges allowed by other physical requirements.
