We consider impact parameter dependence of the polarized and unpolarized
parton densities. Unitarity does not allow factorization of these structure
functions over the Bjorken x and the impact parameter b variables. On the basis
of the particular geometrical model approach we conclude that spin of
constituent quark may have a significant orbital angular momentum component
which can manifest itself through the peripherality of the spin dependent
structure functions.Comment: 4 pages, to appear in the Proceedings of the Workshop Diffraction
2000, Cetraro, Italy, 2-7 September 200
