Furfural uptake was studied with regard to possible mechanisms of inducing germination in ascospores. Uptake was found to involve a large, weakly bound reversible component and a small tightly bound irreversible component. Localization experiments indicate that almost all of the furfural removed from the media is bound to the spore wall. However, a small amount may penetrate into the cytoplasm. The results so far suggest that furfural induces germination by solubilizing or activating a bound or compartmentalized enzyme(s) on the cell membrane or other diffusion barrier of the cell.