INTERNAL STRUCTURE AND NUCLEI IN CELLS OF ESCHERICHIA COLI AS SHOWN BY IMPROVED ELECTRON MICROSCOPIC TECHNIQUES

Abstract

Electron micrographs, using double objective lens with aperture, of microcolonies of E. coli grown on a thin film of collodion overlying nutrient agar, unfixed and unstained, reveal the nucleus as a complex pattern of irregularly shaped light areas between the darker areas at the poles and along the potential lines of division of the bacterial cells. Present limits of resolution do not permit assignment of definite structural details to the nucleus. Fine structure within the bacterial protoplasm is interpreted as a delicate 3-dimensional latticework in which the trabeculae are aggregates of particles of the order of size of protein molecules. Intact cell wall of the E. coli shows no evidence of internal structure. Elliptical and circular segments of cell wall were seen in phage-lysed cells.