All bonds shall be issued, subject to the approval of the Governor, in such forms, denominations, series and numbers, may be of such tenor and maturities, may bear such date or dates, may be in registered or bearer form either as to principal or interest or both with rights of conversion into another form, may be payable in such installments and at such place or places, may bear interest at such rate or rates payable and evidenced in such manner and may contain provisions for redemption at the option of the state to be exercised by said commission at such date or dates prior to their maturity and upon payment of such redemption price or prices, all as shall be provided by said commission in the resolution or resolutions whereunder the bonds are authorized to be issued. The principal of each series of bonds shall mature in annual installments in such amounts as shall be specified in the resolution or resolutions of the said commission under which they are issued, the first of which installments shall mature not later than one year after the date of the bonds of such series, and the last of which installments shall mature not later than 20 years after the date of the bonds of the same series. When each series of bonds is issued, the maturities of the bonds of that series shall, to such extent as may be practicable, be so arranged that during each then succeeding fiscal year of the state the aggregate installments of principal and interest that will mature on all bonds that will be outstanding under this article, immediately following the issuance of the bonds of that series, will be substantially equal; provided, that the determination by the said commission that the requirements of this sentence have been complied with shall be conclusive of such compliance, and the purchasers of the bonds with respect to such determination is made and all subsequent holders thereof shall be fully protected thereby. None of the bonds shall be sold for less than face value plus accrued interest thereon to the date of delivery. All of the bonds shall be sold only at public sale or sales, either on sealed bids or at public auction, after such advertisement as may be prescribed by said commission, to the bidder whose bid reflects the lowest net interest cost to the state computed to the respective maturities of the bonds sold; provided, that if no bid deemed acceptable by said commission is received, all bids may be rejected. The bonds shall be signed in the name of the state by the Governor and countersigned by the chairman of the commission, and the Great Seal of the State of Alabama or a facsimile thereof shall be impressed, printed or otherwise reproduced thereon and shall be attested by the signature of the secretary of state; provided, that facsimile signatures of any one or any two, but not all, of said officers may be reproduced on such bonds in lieu of their manually signing the same. Coupons attached to the bonds and representing installments of interest thereon shall be signed by the facsimile signature of the State Treasurer, which facsimile signature is hereby adopted as due and sufficient authentication of said coupons.