Abstract
The oils from one or more spore forms of three species of Puccinia, four species of Uromyces, and two species of Cronartium have been analyzed, cis-9, 10-Epoxyoctadecanoic acid was the major component for both Cronartium species, and was also found in two species of Uromyces and in one of Puccinia. The oils of uredospores and teliospores of the same rust were always quite similar to each other, but the oils of uredospores and aeciospores of the same rust were sometimes different from each other. An epoxide-hydrolyzing enzyme appeared to be present in the spores of the Cronartium species.