78.310.  Civil service commissioners — appointment. — In cities having a population of twenty thousand and less than thirty thousand the council shall, and in cities having a population of ten thousand and less than twenty thousand the council may immediately after organizing, by ordinance appoint two civil service commissioners, who shall hold office, one until the first Tuesday in April of the second year after his appointment, and one until the first Tuesday in April of the fourth year after his appointment; provided, however, that in all cases in which no civil commissioners are appointed by the council the council shall have the same powers and duties devolving upon such commissioners as provided for in sections 78.010 to 78.420.