(1) If a director--
         (a) becomes subject to any of the disqualifications mentioned in section 10 or is removed under section 11; or
         (b) is absent without leave of the Board for three or more consecutive meetings thereof, his seat shall thereupon become vacant.
     (2) Any director may resign his office by giving notice thereof in writing to the Board and on such resignation being accepted by the Board, or, if such resignation is not accepted sooner, on the expiry of three months from the receipt thereof by the Board, such director shall be deemed to have vacated his office.