Add to ORKGThe writer axpressas his gratitude to the chairman of his committaa. Dr. Clark Harvey, for directing this thesis and for the inspiration, encouragamant and many helpful bits of advice that ha contributed during the writing of the manuscript and the research which preceded it. Grateful acknowledgement is also extended to the other com-mittee members. Dr. Arthur W. Young and Dr. James C. Cross, for their encouragement and constructive criticism. Grateful appreciation is extended to Mr. Lavon L. Ray for his guidance in statistical work, and particularly to Mr. Harvey J. Walker for his timely and helpful criticism and for his vary affec-tive encouragement, without which this paper may navar have bea