  We argue that strong final state rescattering among the secondary particles
created in relativistic heavy ion collisions is essential to understand the
measured Bose-Einstein correlations. The recently suggested ``random walk
models'' which contain only initial state scattering are unable to reproduce
the measured magnitude and K_\perp-dependence of R_\perp in Pb+Pb collisions
and the increase of R_l with increasing size of the collision system.
