A comparison was made of the chromatin subunit ("nu"body) structure present in nuclei from chicken erythrocytes, Tetrahymena cells, and Pisum sativum (pea) buds. All three types of chromatin yielded spherical subunits upon nuclease digestion which were indistinguishable in the electron microscope, and contained approximately the same amount of DNA. There were, however, consistent and significant differences in the digestion patterns of chromatin from the three organisms.