Abstract
Summary
(1) Typical polar granules appear as dense spherical masses, or possibly plates, in electron micrographs of unstained preparations of C. diphtheriae grown on blood infusion agar. (2) In addition to polar granules, needle-like crystals appear in electron micrographs of unstained preparations of C. diphtheriae cells grown on potassium tellurite chocolate agar. (3) The needle-like crystals, as well as the black color, of cell masses of C. diphtheriae grown on potassium tellurite chocolate agar disappear upon the addition of small amounts of bromine water. It is inferred, therefore, that the black color is due to the tellurium metal which occurs in the form of needles. (4) It is to be further inferred that the tellurite ion is able to diffuse through the cell wall and is reduced with the precipitation of tellurium metal within the cell boundaries. (5) With the aid of the electron microscope it is now possible to obtain pictorial records of the location of sites of certain chemical reactions incident to the metabolism of the bacterial cell.
Get full access to this article
View all access options for this article.