The state treasurer shall pay interest on bonds issued under this chapter when due, or upon presentation of the coupon for interest when due, and shall redeem the bonds upon their maturity by paying the principal thereof. All payments must be made from the fund, without a warrant. Each payment so made, in addition to other accounting as provided by law, must be reported by the Bank. The governor may designate a bank or trust company as the fiscal agent of the state at which or by whom or to whom bond principal or interest may be payable. Such agent shall act for the state in the making of such payments under such rules as shall be made by the governor. All moneys in the fund, except the administration fee required to be paid to the Bank, are appropriated for the payment of interest and principal of the bonds. This appropriation may not be repealed, and no provisions made in this chapter for the payment of the bonds and interest may be discontinued until the debt evidenced by the bonds, both principal and interest, has been paid.