The cover picture shows a tobacco plant (Nicotiana tabacum), the chemical formula of jasmonic acid, and two gas chromatograms. The upper chromatogram shows the pattern of volatiles emitted by an untreated plant; the lower chromatogram was obtained from a plant previously treated with the phytohormone jasmonic acid. Clearly, after incubation numerous volatile substances are biosynthesized and released into the air. These induced volatiles, which include mono- and sesquiterpenes, acetogenins, aromatic alcohols and esters, and indole, serve in plant defense and may function as interplant warning signals in particular cases. W. Boland et al. describe the effect of jasmonic acid on tobacco and other selected plants on pp. 1600–1602. Professor Wilhelm Barthlott, Bonn (Germany), provided the picture of the tobacco plant.