Qualitative and quantitative studies of interphase nuclei of barley and rye showed that centromeres occupied the region in the nucleus with the highest proportion of chromatin. Telomeres occupied the opposite end of the nucleus where much less chromatin was present. The pattern was consistent among C-banded nuclei in the light microscope and nuclei in the electron microscope. Microdensitometer scans suggested that the darkly stained centromeric region in the nucleus contained more than twice the proportion of DNA present in the lighter, telomeric, region.