Melvin Cohn and Rodney E. Langman

The Salk Institute, P.O. Box 85800, San Diego, California, 92186-5800

Received 8/15/96; Accepted 9/9/96; On-line 10/1/96

8. ACKNOWLEDGMENTS

Supported by NIH grant RR07716. This paper was written while one of us, Melvin Cohn, was a Scholar-in-Residence at the Fogarty International Center for Advanced Study in the Health Sciences, National Institutes of Health, Bethesda, Maryland, USA.