That it shall be the duty of the secretary and treasurer of the board of regents of the New Mexico normal university [New Mexico highlands university], where bonds have been issued hereunder, to forward to the bank at which said bonds are payable, prior to the date on which any coupons or any principal amount of any of said bonds shall mature, out of the “interest and retirement fund,” a sufficient sum of money to meet said coupons and maturing bonds as the same become due, plus any service charge which said bank shall be entitled to receive for its services.