The Public Defender in counties with a population over 1,000,000 shall appoint assistants, all duly licensed practitioners, as that Public Defender shall deem necessary for the proper discharge of the duties of the office, who shall serve at the pleasure of the Public Defender. The Public Defender shall also, in like manner, appoint clerks and other employees necessary for the transaction of the business of the office. The compensation of and the appropriate number of assistants, clerks, and employees shall be fixed by the County Board and paid out of the county treasury.