Based on a thesis submitted to the Faculty of the Graduate School of State University of New York at Buffalo in partial fulfillment of the requirements for the degree of Master of Science.

Supported in part by U.S.P.H. grant DE-02713 from the National Institute of Dental Research, Bethesda, Md., and in part by General Research Support Grant 5SO1FR05330 awarded to the School of Dentistry, State University of New York at Buffalo.

Given before the Northern California Component of the Angle Society, January 1972.

From the Department of Orthodontics, Emory University School of Dentistry.

Supported by McCandless Fund Grant No. 4363-31 of Emory University.

From the Graduate Department of Orthodontics, University of Toronto, Ontario.

This study was made possible in part through the Medical Research Council of Canada Grant MA-3600, United States Department of Health, Education and Welfare Grant 5 RO1 DEO 28337-03 and by the use of the Burlington Research Centre material which was assisted by funds provided by the Evaluation of Interceptive Orthodontics Grant 605-7-299 of the National Health and Welfare Grants Programme.

Presented at the Quadrennial Meeting of the University of Illinois Orthodontic Alumni Association, March 7, 1972.

Professor, Department of Orthodontics, University of Iowa.

This investigation was supported by research grants DE-01294 and FR-00222 from the National Institutes of Health, Bethesda, Maryland.

A thesis submitted in partial fulfillment of the requirements for the degree of Master of Dental Surgery at the Lucknow University, Lucknow, India.

From the Department of Anatomy and Center for Human Growth and Development, The Univ. of Michigan.