Perpetual debentures: clauses making debentures irredeemable or redeemable only on remote contingencies remain valid under law. Conditions in debentures or deeds securing debentures that make them irredeemable or redeemable only on the happening of a contingency, however remote, or after a very long period are not invalid solely for that reason; this validation applies to instruments issued or executed before or after the statute's commencement and permits perpetual debentures and contingency linked redemption terms to be effective.