Whenever, by consent of Congress, additional territory shall be added to the State of Nevada, on its eastern or southern border, or both, then, until further provided by law, all such added territory lying east of Lander County shall be a part of Lander County; but if any new county or counties shall be created or organized in the eastern or southern part of this state, then any part of such new additional territory lying directly east or south of such new county or counties shall belong, respectively, to such new county or counties.