The Board, upon an application filed or on its own motion, within the time specified, shall, on notice to interested parties, review the decision of the referee. Before rendering its decision, the Board may order the taking of additional evidence by the referee or, in its discretion, the Board may hear additional evidence to be made a part of the record in the case. Upon the basis of evidence previously submitted in the case and such additional evidence as the Board may take or direct to be taken, the Board may affirm, modify, or reverse the findings and conclusions of the referee and shall render its decision thereon. The parties shall be promptly notified by ordinary or certified mail of the findings of fact, conclusions, and decision of the Board. The decision of the Board shall be final unless an appeal is taken therefrom to the Supreme Court. (Amended 1959, No. 329 (Adj. Sess.), § 22, eff. March 1, 1961; 1961, No. 210, § 9, eff. July 11, 1961; 1971, No. 185 (Adj. Sess.), § 195, eff. March 29, 1972; 1989, No. 8, § 3; 1991, No. 82, § 4.)