C Bacillus cereus a gram-positive rod found in the soil. The differential stain technique distinguishes two kinds of organisms.
Magnification alone is not the only aim of a microscope. Stains serve several purposes: Stains differentiate microorganisms from their surrounding environment They allow detailed observation of microbial structures at high magnification Certain staining protocols can help to differentiate between different types of microorganisms.
This can be prevented by never viewing a specimen with the 40X objective after adding immersion oil to a slide.
In order to obtain reliable results it is important to take the following precautions: The cultures to be stained should be young - incubated in broth or on a solid medium until growth is just visible no more than 12 to 18 hours old if possible. For example, one group, the gram-positive bacteria, include the causative agents of the diseases diphtheria, anthrax, tetanus, scarlet fever, and certain forms of pneumonia and tonsillitis.
Demonstrate the Parfocal Property of the Microscope with the Oil Immersion Objective Obtain one of the prepared tissue or bacterial slides. Once again, position an interesting structure in the center of the field, rotate the high dry objective half way out of the way - enough so that you can deposit a small drop of oil onto the center of the lighted specimen.