Presented at the Fifth Annual Meeting of the Inter Society Cytology Council on November 16, 1957, Augusta, Georgia.

Cancer Survey Project of the National Cancer Institute, National Institutes of Health, U.S. Public Health Service, and the University of Louisville School of Medicine, Louisville, Ky.

The author expresses appreciation to Dr. William M. Christopherson, Professor of Pathology, and Dr. James E. Parker, Assistant Professor of Pathology, University of Louisville School of Medicine, for their helpful suggestions and constructive criticism throughout the course of this work, and to Miss Mary Beth Willoughby for the Camera Lucida drawings.