Ultrastructure in the symbiotic association inCornicularia normoerica, fixed in glutaraldehyde, was demonstrated by staining either with potassium permanganate or osmium tetroxide‐thiocarbohydrazide‐osmium tetroxide (OTO) procedures modified for lichen tissues. Channels were observed to originate within the chloroplast, cross the algal cell wall and flare to open space shared with fungal and other algal cells. Tubules within the channels were extensions of chloroplast vesicles. Deeply staining channel walls, tubule elements, spherical bodies within the chloroplast, and organelles of the fungal cytoplasm suggested lipoid substances. The OTO procedure delineated zones in the thick cell walls of both symbionts. Their exterior boundaries were without discernible cellular membranes. The inner zone of the fungal cell wall was finely layered and particulate. No invasive fungal haustoria or zones of dissolution between fungus and alga were seen in any preparation.