A coccus-shaped bacterium is usually spherical, although some appear oval, elongated, or flattened on one side. The correct form, however, should predominate. Also remember that each coccus in an arrangement represents a complete, single, one-celled organism. Small bacilli or bacilli that have just divided by binary fission may at first glance be confused for cocci so they must be observed carefully . You will, however, be able to see bacilli that have not divided and are definitely rod-shaped as well as bacilli in the process of dividing.
Yeasts commonly reproduce asexually by a process called budding .
The approximate size of a microorganism can be determined using an ocular micrometer , an eyepiece that contains a scale which will appear superimposed upon the focused specimen. Before you plug in the microscope, turn the voltage control dial on the right side of the base of the microscope to 1 . Now plug in the microscope and turn it on. Place the slide in the slide holder, center the slide using the two mechanical stage control knobs on the right side of the stage, and place a rounded drop of immersion oil on the area to be observed. Rotate the white-striped 100X oil immersion objective until it is locked into place.