In every county jail where there is a female prisoner, twenty-four-hour supervision shall be provided by a matron appointed by the county board, whose duty it shall be to have entire charge of the female prisoners, and the board may also in its discretion appoint such matron when there is a sick prisoner or one that is a minor under the age of sixteen. Such matrons shall be under the direction of the sheriff or such other person as may be charged with the administrative direction of the jail, shall take the necessary oath before entering upon the duties of the office, and shall be paid by the board from the county treasury only for the time actually engaged; Provided, that in counties having a population in excess of two hundred thousand inhabitants, a deputy or correctional officer shall be hired by the person whose duty it shall be to have charge of the female prisoners and perform those functions required of a deputy related to such duty, at a salary of not less than five hundred dollars per month, which salary shall be drawn out of the county treasury. Such matron, deputy, or correctional officer shall, when required, report to the board or district judges.