ELECTRON AND LIGHT MICROSCOPIC STUDIES OF BACTERIAL NUCLEI

Abstract
In young cells of E. coli. fixed in OSO4 vapor and shadowed with chromium, the nuclear sites may appear either as irregularly shaped areas of less electron-scattering power than the surrounding cytoplasm or as depressions over which the cytoplasm has collapsed. Both observations support the conclusion that the nuclear sites are areas of less density (mass per volume) then the enveloping cytoplasm. The patterns of cytoplasm and nuclear sites in electron micrographs of unfixed and OsO4-fixed cells correspond essentially with the pictures seen with the phase microscope in the living cells by Tulasne and Stempen.