The commissioner shall make an annual examination of the securities received by him from each insurer. If it appears at any time that the securities deposited by any such insurer amount to less than the sum required for the purposes for which the deposit was made, he shall notify the insurer thereof. Unless the deficiency is made up within thirty days after the notice, the commissioner shall revoke the insurer’s certificate of authority, countermand all the certificates issued to the insurer under this article, and give notice thereof to the officers of the several States to whom the certificate has been transmitted.