Section 73. If the instrument creating or declaring a trust or other equitable interest contains an express power to sell, mortgage or deal with the land in any manner, such power shall be stated in the certificate of title by the words ''with power to sell'', or ''power to mortgage'', and by apt words of description in case of other powers. No instrument which transfers, mortgages or in any way deals with registered land held in trust shall be registered, unless the power thereto enabling is expressly conferred in the trust instrument, or unless the decree of a court of competent jurisdiction on a bill for instructions or other proceeding has construed the instrument in favor of the power. In such case a certified copy of such decree may be filed with the assistant recorder, and he shall make registration in accordance therewith.