... Based on the measurements of the Stokes parameters in the continuum and in the broad 0.6563 nm hydrogen emission line obtained with the 6-m telescope for the Seyfert galaxy Mkn 6, secular variability of the hydrogen line profile polarization was discovered; a time lag of less than 2 days between the continuum flux and the polarized continuum emission was determined which corresponds to the size of the region where the polarization of the continuum occurs, less than 0.001 pc. ...