In counties having a population exceeding sixty thousand inhabitants, and not more than two hundred thousand inhabitants, there may be spent under the direction and control of the county attorney of said county a sum of money not exceeding five hundred dollars in any one year, to be paid out of the general fund of the county, for the employment of a detective or detectives, the same to be appointed by the county attorney at such rates of compensation per day as may be fixed by said officer, and said appointment may be revoked by him at any time. In counties having a population exceeding two hundred thousand inhabitants, there may be spent under the direction and control of the county attorney of said county a sum of money not exceeding fifteen hundred dollars in any one year, to be paid out of the general fund of the county, for the employment of a detective or detectives, the same to be appointed by the county attorney at such rates of compensation per day as may be fixed by said officer, and said appointment may be revoked by him at any time.