Section 1. COUNTIES TO WHICH APPLICABLE. The County Boards of School Trustees may employ rural supervisors of Van Zandt, Panola, Nacogdoches, Jasper, Cass, Live Oak, Anderson, Scurry, Wood, Denton, Shelby, Morris, Parker, Nolan, Titus, Wise and Lamar Counties, to plan, outline, and supervise the work of the primary and intermediate grades of the rural schools of the counties.