led an expedition to Vietnam at the request of the American Association for the Advancement of Science. The group showed that the United States was mistaking civilian rice fields for enemy soldiers’ crops, prompting Nixon to end US herbicide operations in Vietnam. During the Cold War, Meselson’s investigations into “yellow rain”— purportedly a mycotoxin produced by the former Soviet Union to destroy crops in Laos and Cambodia—proved that the substance in question was actually bee droppings, pollen eaten by the insects that they excreted in massive showers. Today, Meselson helps direct the Harvard Sussex Program, which aims to increase the contribution of scholarship to public policy issues concerning biological and chemical weapons. The program is trying to persuade governments to adopt a treaty that would make purveyors of biological and chemical weapons international criminals. Information on present and past Lasker Awards can be found at http: //www.laskerfoundation.org.