The county attorney of any county in this state who has no assistant is hereby authorized to appoint, with the consent of the county board of the county, one or more attorneys for assistance in the performance of duties. Each assistant shall have the same duties and be subject to the same liabilities as the county attorney and hold office during the pleasure of the county attorney. Each assistant shall be appointed in writing and the assistant’s oath and appointment shall be recorded with the county recorder. The county board of such county shall fix the salary of each assistant county attorney appointed pursuant to the provisions of this section, and the salary when so fixed by such county board shall thereafter be paid by the county in equal monthly installments upon the warrant of the county auditor during the period for which such salary is so fixed or during such portion thereof as an assistant county attorney continues in office.