The quantities of gaseous and volatile metabolites liberated by germinating seeds and seedlings appeared to be related, in general, to the amount of storage substances present in the seeds. Both qualitative and quantitative differences were found between various plant species and varieties of both angiosperms and gymnosperms. The release of volatile compounds preceded the appearance of the first root and, with most seeds, was greatest in the first 24 to 48 h. Organic volatiles could be detected, by gas chromatography, in as little as 5% of the atmosphere from one germinating seed. All seeds that were studied liberated ethanol, and most seeds evolved methanol, formaldehyde, acetaldehyde, formic acid, ethylene, and propylene. Propionaldehyde and (or) acetone was also evolved by cotton, pea, and yellow pine. The possible source of these volatile metabolites and their ecological implications are discussed.