Section 4
SEC. 4. Lands acquired under this Act shall not, except in favor of the Government or any of its branches or institutions, or legally constituted banking corporations, be subject to encumbrance or alienation within fifteen years after the date of the issuance of the transfer certificate of title to the purchaser, nor shall they become liable to the satisfaction of any debt contracted prior to the expiration of said period: Provided, however, That such lands may be mortgaged even before said period has expired. Every conveyance shall be subject to repurchase by the original purchaser or his legal heirs within a period of five years from the date of the conveyance.