The public health risk of animal organ and tissue transplantation into humans.

Sheila Jasanoff ,man William A. Lester Jr. Simon A. Levin Marcia C. Linn Michael J. Novacek Anna C. Roosevelt Jean E. Taylor Nancy S. Wexler William T. Golden Treasurer Richard S. Nicholson Executive Officer * SCIENCE (ISSN 0036-8075) is published weekly on Friday, except the last week in December, by the American Association for the Advancement of Science, 1200 New York Avenue, NW, Washington, DC 20005. Periodicals Mail postage (publication No. 484460) paid at Washington. DC. and additional mailing offices. Copyright C 1996 by the American Association for the Advancement of Science. The title SCIENCE is a registered trademark of the AAAS. Domestic individual membership and subscription (51 issues): $102 ($55 allocated to subscription). Domestic institutional subscription (51 issues): $250. Foreign postage extra: Mexico, Caribbean (surface mail) $55; other countries (air assist delivery) $90. First class, airmail, student, and emeritus rates on request. Canadian rates with GST available upon request. GST #1254 88122. Printed in the U.S.A.