  The small fraction of the quark polarization of the nucleon obtained in deep
inelastic lepton scattering is a consequence of a wrong assumption on the flux
of polarized virtual photons in the analysis of the data. The true flux of
polarized photons is due to fluctuations into strongly interacting
quark-antiquarks at least 20\% smaller than assumed and, therefore, the quark
polarization is larger. Realizing this peculiarity the quark polarization
agrees with that given by the Ellis-Jaffe sum rule, i.e. is consistent with the
prediction derived from the experimentally determined weak coupling constants.
It also solves the problem with the under-exhaustion of the fundamental
Bjorken-sum rule. However, it has to be realized that the fluctuations render
it impossible to measure the quark spin with credibility.

High Energy Physics - Phenomenology