Each supplemental petition or answer, made by either party, shall be a response to the last preceding pleading by the other party, and shall not repeat allegations formerly pleaded further than is necessary as an introduction to that which is stated in the pleading then being drawn up. These instruments, to wit, the original petition and its several supplements, and the original answer and its several supplements, shall respectively, constitute separate and distinct parts of the pleadings of each party; and the position and identity, by number and name, with the indorsement of each instrument, shall be preserved throughout the pleadings of either party.