The directors named in the articles of incorporation must meet within one week after the filing of said articles and organize by the election of the president, who shall be one of their number, a secretary and a treasurer; and their successors must so meet and organize immediately after their election. Directors must perform the duties enjoined upon them by law and the bylaws of the corporation. A majority of the directors shall constitute a board for the transaction of business, and every decision of a majority of the directors forming such board, made when duly assembled and in session as such board, shall be valid as a corporate act.