1. Wellcome Research Laboratories, Beckenham, Kent, England
2. University of Aarhus, Aarhus, Denmark
3. National Institutes of Health, Bethesda, Maryland
4. New York State Veterinary College, Cornell University, Ithaca
5. Wistar Institute, Philadelphia, Pennsylvania
6. Lister Institute of Preventive Medicine, London, England
7. Hebrew University, Hadassah Medical School, Jerusalem, Israel
8. Children's Hospital, Columbus, Ohio
9. Walter Reed Army Institute of Research, Washington, D. C.