From the money appropriated in Section 67-3-57 N.M. Stat. Ann., the state treasurer shall set aside each month out of the funds prescribed by law for the payment thereof a sufficient sum to pay the interest accrued each month on each series of state highway debentures then outstanding and, during the twelve months next preceding the maturity of each series of such debentures, he shall set aside from said funds sufficient money to provide for the payment of the principal thereof at maturity. The money so set aside shall be disbursed by the state treasurer only for the payment of the principal and interest of the series of the state highway debentures for which the money is set aside. The remainder of the money appropriated in Section 67-3-57 N.M. Stat. Ann. shall be disbursed upon the order of the state transportation commission or its duly authorized agent in the manner provided by law for disbursement of money in the state road fund.