The minimum sizes of four quasi-stellar objects, each of which exhibits an absorption redshift greater than its emission redshift, have been calculated by assuming that the absorption lines originate in clouds which are falling radially towards the quasi-stellar objects along the line of sight, and that the quasi-stellar objects are at a distance inferred from the cosmological interpretation of their redshifts. It has been found that the radii are greater than 10 pc and that the masses are of the order of 10¹² M(.).