  The near membrane layer is defined as a region where the concentration of the
substance transported across the membrane drops $k$ times. The time evolution
of such a layer is studied experimentally by means of the laser interferometric
method. It is shown that within the experimental errors the thickness of the
near membrane layer grows in time as $a \sqrt t$ with the coefficient $a$ being
independent of the initial concentration and the membrane permeability. Time
evolution of the near membrane layers is also analyzed within the theoretical
approach earlier developed by one of us. The regularities found experimentally
fully agree with the theoretical expectations.
