Sec. 5. EXEMPTIONS; PARTIAL INVALIDITY. The employment of rural school supervisors, under the terms of this Act shall exempt the County Superintendent from holding a Teachers' Institute for rural teachers, including teachers of independent districts of fewer than five hundred (500) scholastics, and exempt the rural teachers of the County from attendance upon a Teachers' Institute as provided for in Article 2691, Revised Statutes of 1925, and as amended by the 40th Legislature. It is hereby declared that if any clause, phrase, provision or section of this bill should be invalid or unconstitutional, that the Legislature would have nevertheless passed the remaining portions of said bill without including the phrase, clause, provision or section so declared invalid or unconstitutional.