If any person shall convey any real estate by deed purporting to convey it in fee simple absolute, or any less estate, and shall not at the time of the conveyance have the legal estate in the lands, but shall afterwards acquire it, then the legal or equitable estate afterwards acquired shall immediately pass to the grantee and the conveyance shall be as valid as if the legal or equitable estate had been in the grantor at the time of the conveyance.