No trustee, and no person who has recently ceased to be a trustee, may, without the permission of a principal Civil Court of original jurisdiction, buy or become mortgagee or lessee of the trust-property or any part thereof; and such permission shall not be given unless the proposed purchase, mortgage or lease is manifestly for the advantage of the beneficiary.
     Trustee for purchase.-- And no trustee whose duty it is to buy or to obtain a mortgage or lease of particular property for the beneficiary may buy it, or any part the reof, or obtain a mortgage or lease of it, or any part thereof, for himself.