  The spectra of Wolf-Rayet (WR) stars exhibit strong, broad emission lines
that originate in the wind. These winds are radiatively driven and are
susceptible to hydrodynamic instabilities that result in the formation of
clumps. When modelling spectra of WR stars the volume-filling factor (VFF)
approach is usually employed to treat clumpy winds. However, it is based on the
assumption that the entire wind mass resides in optically thin clumps, which is
not necessarily justifiable in dense winds. To test the validity of the VFF
approach we use a previously described method of treating clumping, the
``Shell'' approach, to study line and continuum formation in the dense wind of
the WN4 star, HD 50896. Our models indicate that fully intact spherical shells
are in tension with observed spectra; a persistent ``dip'' in emission lines
occurs at line centre. Removing this dip requires our models to use ``broken''
shells -- shells that are highly decoherent laterally. This insinuates that the
wind of HD 50896, and by extension the winds of other WR stars, are comprised
of small laterally confined and radially compressed clumps -- clumps smaller
than the Sobolev length. We discuss some of the conditions necessary for the
VFF approach to be valid.
