51. Who may negotiate. Every sole maker, drawer, payees or indorsee, or all of several joint makers, drawers, payees or indorsees, of a negotiable instrument may, if the negotiability of such instrument has not been restricted or excluded as mentioned in section 50, indorse and negotiate the same. Explanation.- Nothing in this section enables a maker or drawer to indorse or negotiate an instrument, unless he is in lawful possession or is holder thereof; or enables a payee or indorsee to indorse or negotiate an instrument, unless he is holder thereof. Illustration A bill is drawn payable to A or order. A indorses it to B, the indoresement not containing the words" or order" or any equivalent words. B may negotiate the instrument.