All expenditures shall be made by order of the board and shall be paid on warrants issued by the comptroller based on vouchers approved by the chairman of the board or some other officer of the university designated by him in writing to the comptroller, and countersigned by the secretary of the board or some other officer of the university designated by the secretary in writing to the comptroller.Acts 1971, 62nd Leg., p. 3250, ch. 1024, art. 1, Sec. 1, eff. Sept. 1, 1971.