21. After the issue of a notification under section 20, no rights shall be acquired in or over the land comprised in such notification, except by succession or under grant or contract in writing made or entered into, with the previous sanction of the Government, by or on behalf of the owner or some person in whom such right was vested when the notification was issued; and no fresh clearings for cultivation or for any other purpose, and cutting, conversion or removal of timber or the collection, manufacture or removal of other forest-produce, shall be made in such land except in accordance with such rules, if any, as may be made by the Government in this behalf.