(2) In the absence of the President, the Senior ex-officio Member present or, if there be only one ex-officio Member present, then such Member, shall preside at the meetings of the Council, and the powers vested in the Council shall be exercised only at the meetings of the Council at which the President or some one of the ex-officio Members and not less than one-half of the total number of members of the Council shall be present.