§ 68. Exemption of securities. The provisions of article twenty-three-a of the general business law shall not apply to any note, bond or other evidence of indebtedness issued by any cooperative or foreign corporation doing business in this state pursuant to this chapter to United States of America or any agency or instrumentality thereof, or to any mortgage, deed of trust or other instrument executed to secure the same. The provisions of said article twenty-three-a shall not apply to the issuance of membership certificates by any cooperative or any such foreign corporation.