  The Drell-Hearn-Gerasimov sum-rule is really two sum-rules: one for each of
the valence and the sea/glue contributions to the nucleon wavefunction. The
convergence of these sum-rules follows from the Froissart bound for spin
dependent processes in QCD and is necessary for the consistency of the
constituent quark model of low energy QCD. Some challenges for future polarised
photoproduction experiments, for example at ELFE, are discussed.
