Small, specially prepared gold alloy discs were recessed into the right and left posterior surfaces of duplicate maxillary dentures. At selected time intervals, a disc was removed from each side of the denture and prepared for examination with a scanning electron microscope (SEM). A thin, peeling film of pellicle was seen on the discs removed after two hours and projections designated "hemispherical globules" formed on the pellicle within the next seven hours.