1. Amgen Inc., Thousand Oaks, CA 91320.
2. Department of Biology, California Institute of Technology, Pasadena, CA 91125.
3. Vicam, Inc., Somerville, MA 02145.
4. Arbor Acres Farm, Inc., Marlborough Road, Glastonbury, CT 06033.
5. Poultry Disease Research Center, University of Georgia, Athens, GA 30601.