  We follow the contraction and evolution of a typical Jupiter-mass clump
created by the disk instability mechanism, and compute the rate of planetesimal
capture during this evolution. We show that such a clump has a slow contraction
phase lasting ~3x10^5 years. By following the trajectories of planetesimals as
they pass through the envelope of the protoplanet, we compute the cross-section
for planetesimal capture at all stages of the protoplanet's evolution. We show
that the protoplanet can capture a large fraction of the solid material in its
feeding zone, which will lead to an enrichment of the protoplanet in heavy
elements. The exact amount of this enrichment depends upon, but is not very
sensitive to the size and random speed of the planetesimals.
