When a bill payable to order on demand is drawn on a banker, and the banker on whom it is drawn pays the bill in good faith and in the ordinary course of business, it is not incumbent on the banker to show that the indorsement of the payee or any subsequent indorsement was made by or under the authority of the person whose indorsement it purports to be, and the banker is deemed to have paid the bill in due course, although such indorsement has been forged or made without authority.