§ 24. Income debentures. 1. With the approval of the supervising agency or of the commissioner, as the case may be, the certificate of incorporation, or an amended certificate may authorize the issuance of income debentures bearing no greater interest than six per centum per annum except as otherwise provided in this article. After the incorporation of a company, the directors thereof may, with the consent of two-thirds of the holders of the preferred stock issued and outstanding offer to the stockholders of the company, the privilege of exchanging their stock in such quantities and at such times as may be approved by the supervising agency or the commissioner, as the case may be, for such income debentures. In no event, shall the amount of stock of the company be less than a per centum of the total of stock and income debentures, to be fixed by the supervising agency or by the commissioner, as the case may be.

2. Such income debentures and any instrument under which they are issued may contain such other provisions, including provision for amortization by serial maturities, through the operation of a sinking fund or otherwise, as may be approved by the supervising agency or by the commissioner, as the case may be.