The Scheme shall be laid, as soon as may be, after it is framed before each House of Parliament while it is in session for a total period of thirty days which may be comprised in one session or in two successive sessions, and if, before the expiry of the session in which it is so laid or the session immediately following, both Houses agree in making any modification in any provision of the Scheme or both Houses agree that any provision in the Scheme should not be made, the provision of the Scheme shall thereafter have effect only in such modified form or be of no effect, as the case may be, so, however, that any such modification or annulment shall be without prejudice to the validity of anything previously done under that provision.