The articles of incorporation of the corporation and amendments to the articles shall be submitted to the department of commerce and insurance. The approval of the articles and amendments by the commissioner of commerce and insurance shall be endorsed on the articles and amendments before the articles and amendments are filed with the secretary of state; provided, that if the articles of incorporation of the corporation have been filed with the secretary of state prior to February 24, 1945, the approval of the articles by the commissioner shall be evidenced by a separate instrument in writing, filed with the secretary of state.