Section 23
SEC. 23. No person, corporation, association, or partnership other than those mentioned in the last preceding section may acquire or own agricultural public land or land of any other denomination or classification, which is at the time or was originally, really or presumptively, of the public domain, or any permanent improvement thereon, or any real right on such land and improvement: Provided, however, That persons, corporations, associations or partnerships which, at the date upon which the Philippine Constitution took effect, held agricultural public lands or land of any other denomination, that belonged originally, really or presumptively, to the public domain, or permanent improvements on such lands, or a real right upon such lands and Constitution took improvements, having acquired the same under the laws and regulations in force at the date of such acquisition, shall be authorized to continue holding the same as if such persons, corporations, associations, or partnerships were qualified under the last preceding section; but they shall not encumber, convey, or alienate the same to persons, corporations, associations, or partnerships not included in section twenty-two of this Act, except by reason of hereditary succession, duly legalized and acknowledged by competent courts.