  The probabilistic model of parton distributions, previously developed by one
of the authors, is generalized to include the transversity distribution. When
interference effects are attributed to quark level only, the intrinsic quark
motion produces the transversity, which is about twice as large as the usual
polarized distribution. The applicability of such a picture is considered and
possible corrections, accounting for interference effects at the parton-hadron
transition stage are discussed.
