The resolution or order providing for the issuance of such bonds may reserve unto the governing authority the right to call in, pay, and redeem such bonds in the inverse order of their numbers and maturities, prior to the maturity date or dates thereof on any interest payment date. Whenever it is desired to exercise the aforesaid right, if reserved in such resolution or order, the governing authority shall cause written notice thereof to be delivered to the bank or office at which such bonds are payable. Such notice shall be so delivered not less than thirty days prior to the interest payment date designated for the redemption of such bonds, after which date so designated, no further interest shall accrue on the bonds so called for redemption. Such refunding bonds may be sold for not less than par and accrued interest, or may be exchanged at par for bonds and interest coupons to be refunded thereby.
The board of supervisors may accept county bonds, consolidated school district bonds, rural separate school district bonds or separate road district bonds, as the case may be, at not more than par and interest accruing thereon at the rate fixed in the bonds to be refunded in exchange for said refunding county bonds, consolidated school district bonds, rural separate school district bonds or separate road district bonds, as the case may be. In accepting any bond in exchange for, or in payment of, any such refunding bond, no bond shall be accepted in such exchange or payment that is secured by the property of a smaller or different district, or other subdivision, than that securing the refunding bonds so issued.