Every such director shall, within 30 days after his election, take and subscribe, in duplicate, an oath that he will diligently and honestly perform his duties as such director, not knowingly violate or permit to be violated any provision of the banking law of this state and that he is the owner in good faith of the shares of stock of the bank or company required to qualify him for such office, standing in his own name on its books. A copy of such oath shall be forthwith filed with the Superintendent of Banks. No director shall perform the duties of his office until such oath is made, and in case a director fails to make such oath, his place on the board shall be declared vacant and his successor elected as prescribed by the bylaws of the bank, such successor being required to have the same qualifications and take the same oath as provided by this chapter.