Chapter II - Bacterial Anatomy

Abstract

This chapter provides an overview of bacterial anatomy. Bacteria are the smallest of free-living organisms, the average diameter of a bacterial cell being about 1/1000 mm. Because of their very small size, a microscope is essential for examining bacteria. There are two broad methods of microscopy in use, namely, light microscopy, using visible or ultraviolet light, and electron microscopy, using a beam of electrons. In the case of ultraviolet light, a special light source (mercury vapor lamp) is used in conjunction with filters to eliminate light of other wavelengths and quartz lenses are used to allow the ultraviolet light to pass. As already mentioned, the image must be recorded photographically. It seems evident that some form of nuclear apparatus must be responsible for the transfer of hereditary characters in bacteria, but it has not been possible to demonstrate its presence satisfactorily until recently. However, by special staining methods such as the Feulgen technique that stains nuclear chromatin in plant and animal cells, intracellular bodies called chromatin bodies can be detected that go through a regular cycle of division during the growth of the bacterial cell.