Said notes shall be issued to mature in one or more months, but not to exceed twelve months, after date of issue, shall be payable to bearer, shall bear a rate of interest not to exceed fourteen percent per annum from date until maturity, and shall be in such form as the county commission may prescribe. If sufficient funds shall not be on hand to pay any of said notes at maturity the same shall continue to bear interest at the rate therein provided until necessary funds are available for the payment thereof.