Section 49 or by leases.C1

Where any land F1... in Scotland shall, by virtue of any tack, assignation of tack, or other deed or writing ..., be held in lease, either directly or through trustees for his behoof, by a party of full age born after the date of such tack, assignation of tack, or other deed or writing, such party shall not be in any way affected by any prohibitions, conditions, restrictions, or limitations which may be contained in such tack, assignation of tack, or other deed or writing, or by which the same or the interest of such party therein may be qualified, such prohibitions, conditions, restrictions, or limitations being of the nature of prohibitions, conditions, restrictions, or limitations of entail, or intended to regulate the succession of such party, or to limit, restrict, or abridge his possession or enjoyment of such land ... in favour of any future heir: Provided always, that it shall be lawful to the proprietor of whom such lease is held to enforce any prohibitions, conditions, restrictions, or limitations contained in such tack, assignation of tack, or other deed or writing which shall have been inserted therein for the bona fide purpose of protecting the just rights and interests of such proprietor, in so far as such enforcement may be necessary in order to such protection.