The Secretary of the Interior is authorized to cause condemnation proceedings to be instituted in the name of the United States under the provisions of section 3113 of title 40, to acquire title to the lands, interests therein, or rights pertaining thereto that are privately owned within the boundaries of the said national park, and such property, when acquired, shall become a part thereof: Provided, That when the owner of such lands, interests therein, or rights pertaining thereto shall fix a price for the same, which, in the opinion of the Secretary of the Interior, shall be reasonable, the Secretary may purchase the same without further delay: Provided further, That the Secretary of the Interior is authorized to accept, on behalf of the United States, donations of land, interests therein, or rights pertaining thereto required for the Theodore Roosevelt National Park: And provided further, That title and evidence of title to land and interests therein acquired for said park shall be satisfactory to the Attorney General.