Most bacteria are quite colourless and transparent and have a refractive index similar to that of the aqueous fluids in which they are suspended. Unless the diaphragm is carefully adjusted usually there is considerable difficulty in bringing the organisms into focus. Small size of bacteria can be seen with the ordinary light microscope unless the organisms are stained.Some staining techniques, such as the Gram and Ziel Neelsen stains, although of great diagnostic value because of their differential staining properties for specific bacteria, reveal little internal structure. Other such as Feulgen stain for nuclear bodies, demonstrates specific structure. HANGING DROP TECHNIQUE The techniques employed are meant for microscopic observation of living bacteria. The motility The study of bacterial morphology is performed in two ways: 1. Observing unstained cells live by hanging drop preparation. 2. Observing dead cells by making use of chemical nature of ...