SECTION 1. Subsection six of section fifty-four of Act Numbered Nine hundred and twenty-six, entitled ''The Public Land Act/' is hereby amended so as to read as follows:
"6. All persons who by themselves or their predecessors in interest have been in the open, continuous, exclusive; and notorious possession and occupation of agricultural public lands, as defined by said Act of Congress of July first. nineteen hundred and two. under a bona fide claim of ownership except as against the Government, for a period of ten years next preceding the twenty-sixth, day of July, nineteen hundred and four, except when prevented by war or force majeure, shall be conclusively presumed to have performed all the conditions essential to a government grant and to have received the same, and shall be entitled to a certificate of title to such land under the provisions of this chapter."