1. Department of Anatomy, Johns Hopkins University, School of Medicine, Baltimore, Md., and the Department of Biological Sciences, Hunter College, City University of New York, New York, N. Y.
2. Johns Hopkins University School of Medicine, Baltimore, Md.; Leukemia Societty of America Fellow.
3. Department of Biological Sciences, Hunter College, City University of New York, New York, N.Y.
4. The Johns Hopkins University School of Medicine, Baltimore, Md.