Each county commission may divide the county into convenient townships, and as occasion may require erect new townships, subdivide townships already established, organize better township lines, and may, upon the petition in writing, of not less than twenty-five percent of the legally qualified voters of each township affected, as such vote was cast in the last preceding general election for the office receiving the greatest number of votes in the township or townships affected, consolidate two or more existing townships into one township, or otherwise reduce the number of townships, or change the boundary lines thereof, as may be deemed advisable.