13. (1) The meetings of the Board shall be held at such times and places as may be prescribed: Provided that meeting of the Board may also be otherwise convened by the Director-General if he so desires. (2) Five Trustees including the Chairman shall form the quorum at a meeting of the Board. (3) At a meeting of the Board, each Trustee shall have one vote, but in the event of equality of votes, the Chairman or his nominee shall have a second or casting vote. (4) The meeting of the Board shall be presided over by the Chairman and in his absence by such other Trustee who may be so nominated by the Chairman as provided in section 8(2) and in the absence of both of them, by a person elected for the purpose by the Trustees present from amongst themselves. (5) No act or proceeding of the Board shall be invalid merely on the ground of the existence of any vacancy in, or any defect in the constitution of, the Board. (6) All acts done by a person acting in good faith as the Director-General of the Protishthan or a Trustee of the Board shall be valid, notwithstanding that it may afterwards be discovered that his appointment was invalid by reason of any defect or disqualification or had terminated by virtue of any provision contained in any law for the time being in force: Provided that nothing in this section shall be deemed to give validity to any act of the Director-General or a Trustee of the Board after his appointment has been shown to be invalid or to have been terminated.