1. National Institute of Arthritis and Metabolic Diseases, National Institutes of Health, Public Health Service, U. S. Department of Health, Education, and Welfare, Bethesda, Md.
2. National Institutes of Health, Bethesda, Md.
3. Section on Hematology, Laboratory of Experimental Pathology, The National Institute of Arthritis and Metabolic Diseases, National Institutes of Health, Bethesda, Md.
4. Section on Hematology, Clinical Center, National Institutes of Health, Bethesda, Md.