The Department of Libraries shall consist of the County Board of Library Trustees, the County Librarian and all other officers, agents and employees in the public library system of the County. The Board of Library Trustees shall be constituted and shall do and perform such duties and functions as may from time to time be provided by law. All references of this Charter to the head of an office or department shall be construed as including the County Librarian as head of the Department of Libraries, but nothing in this Charter contained shall be held or construed as affecting or any anywise changing the organization, operation and administration of the County library system by the Board of Library Trustees as provided by public general law.