Increasing productivity and efficiency in agriculture.

* SCIENCE Is published weely on Friday, except the last week In Dece ber, by the AmeIcan AsocatIon for the Advancent of Scien, 1333 H Stret, NW, Washington, DC 20005. Second-dass postage (publication No. 484480) paid at Washington, DC, and at an additional entry. Now combined with The ScletIfc Monthly Copyright C 1986 by the American Association for the Advancement of Science. Domestic Individual membership and subscription (51 issues): $60. Domestic institutional subscription (51 issues): $98. Foreign postage extra: Canada $24, other (surface mail) $27, air-surface via Amnsterdam $65. First class, airmail, school-year, and student rates on request. Single copies $2.50 ($3 by mail); back issues $4 ($4.50 by mail); Biotechnoiogy issue, $5.50 ($6 by mail); cassroom rates on request. Change of address: allow 6 weeks, giving old and new addresses and seven-digit account number. Authorization to photocopy material for internal or personal use under circumstances not falling within the fair use provisions of the Copyright Act is granted by AAAS to libraries and other users registered with the Copyright Clesrance Center (CCC) Transactional Reporting Service, provided that the base fee of $1 per copy plus $0.10 per page is paid directly to CCC, 21 Congress Street, Salem, Massachusetts 01970. The identification code for Schnoe is 003-8075/83 $1 + .10. Postmaster: Send Form 3579 to Science, 1333 H Street, NW, Washington, DC 20005. Science is indexed in the Reades Guide to Periodical Literature and in several specialized indexes. * The American Association for the Advancement of Science was founded in 1848 and incorporated in 1874. Its objects are to further the work of scientists, to facilitate cooperation among them, to foster scentific freedom and responsibility, to improve the effectiveness of science in the promotion of human welfare, and to increase public understanding and appreciation of the importance and promise of the methods of science in human progress.