Classification of Common Bacteria

Student Instruction

MORPHOLOGICAL EXAMINATION:  Choose a prepared slide labeled “Typical Bacteria” or “Bacterial Types.”  Focus with all  objectives in sequence;  sketch what you see on high-dry and then proceed to oil-immersion.  Sketch the examples you see on oil.  Look for the different morphological types.  Describe the bacteria you see according to shape and arrangement:
 

                   BY SHAPE:          coccus – round
                                                bacillus – rod
                                                spirillum – spiral or curve

Prepare a cheek-cell from your own mouth by using a woodstick applicator and gently scrape the interior cheek lining.  You may also choose the “scurf of the teeth”, (near the gum as described by Leeuwenhoek).   Spread the sample in the center of a clean glass slide and let the smear air dry.  Drop two drops of the methylene blue stain on the dry smear and wait two minutes before gently rinsing.  Blot gently to remove excess water, then observe on all powers.  Sketch the eukaryotic squamous cell and any bacterial cells (prokaryotic) which are seen.  Classify the bacterial cells according to shape and arrangement.