[...]... tweezers Learning Objectives Each student should be able to 1 Understand the principles behind dark-field microscopy 2 Correctly use the dark-field microscope 3 Make a wet-mount and examine it for spirochetes with the dark-field microscope Suggested Reading in Textbook 1 The Dark-Field Microscope, section 2.2; see also figures 2.7 and 2.8 Pronunciation Guide Treponema denticola (trep-o-NE-mah dent-A-cola)... = _ mm 18 Complete the following on units of measurement: Unit Abbreviation Value a 1 centimeter 10 –2 meter b 1 millimeter mm c Ȗm 10 –6 meter d 1 nanometer 10 –9 meter e 1 angstrom 10 10 meter 12 Microscopic Techniques Harley−Prescott: Laboratory Exercises in Microbiology, Fifth Edition I Microscopic Techniques © The McGraw−Hill Companies, 2002 2 The Hanging Drop... their hands after completing laboratory activities and should remove protective clothing before leaving the laboratory 10 There should be no eating, drinking, or smoking in the work area Summary of Universal Precautions and Laboratory Safety Procedures Harley−Prescott: Laboratory Exercises in Microbiology, Fifth Edition I Microscopic Techniques © The McGraw−Hill Companies, 2002 Introduction PA RT O N... image against a dark background (figures 3 .1 3.2) Since light objects against a dark background are seen more clearly by the eye than the reverse, dark-field microscopy is useful in observing unstained living microorganisms, microorganisms that are difficult to stain, and spirochetes (figure 3.2), which are poorly defined by bright-field microscopy 17 Harley−Prescott: Laboratory Exercises in Microbiology, ... contaminated slides in a container with disinfectant solution 7 Complete the report for exercise 2 Figure 2 .1 Preparation of a Hanging Drop Slide Toothpick Vaseline ring Slide concavity (a) Inoculating loop Drop of bacterial culture Procedure 1 With a toothpick, spread a small ring of Vaseline around the concavity of a depression slide (figure 2.1a) Do not use too much Vaseline 2 After thoroughly mixing... Hanging Drop Slide and Bacterial Motility SAFETY PRECAUTIONS Be careful with the Bunsen burner flame Slides and coverslips are glass Do not cut yourself when using them Dispose of any broken glass in the appropriately labeled container Discard contaminated depression slides in a container with disinfectant Pronunciation Guide Bacillus cereus (bah-SIL-lus SEE-ree-us) Pseudomonas aeruginosa (soo-do-MO-nas... Pseudomonas aeruginosa (soo-do-MO-nas a-ruh-jinOH-sah) Spirillum volutans (spy-RIL-lum VOL-u-tans) Materials per Student 2 4- to 48-hour tryptic soy broth cultures of Pseudomonas aeruginosa (ATCC 10 145, small, motile bacillus), Bacillus cereus (ATCC 217 68, large, motile bacillus), and Spirillum volutans (ATCC 19 554, spiral, motile bacterium) microscope or phase-contrast microscope lens paper and lens... basic principles behind phasecontrast microscopy 2 Correctly use the phase-contrast microscope 3 Make a wet-mount of pond water and observe some of the transparent, colorless microorganisms that are present Suggested Reading in Textbook 1 The Phase-Contrast Microscope, section 2.2; see also figures 2.8 and 2.9 Pronunciation Guide Bacillus (bah-SIL-lus) Clostridium (klos-STRID-ee-um) Principles Certain transparent,... observer, who tried to look at everything with his microscopes Antony van Leeuwenhoek (16 32 17 23) Leeuwenhoek was a master at grinding lenses for his microscopes Working in Delft, Holland, in the mid -1 6 00s, he is considered the greatest early microscopist Those little animals were everywhere! He told the Royal Society of finding swarms of those subvisible things in his mouth—of all places: “Although... micrometer in place, it would appear as shown in figure 1. 4a In like manner, the stage micrometer would appear as illustrated in figure 1. 4b 2 When in place, the two micrometers appear as shown in figure 1. 4c Turn the ocular in the body tube until the lines of the ocular micrometer are parallel with those of the stage micrometer (figure 1. 4d ) Match the lines at the left edges of the two micrometers by moving . lighting and adjusting a laboratory burner c. using an incubator Laboratory Thinking Skills A student successfully completing basic microbiol- ogy will demonstrate an increased skill level in 1. . procedure involved in handling infectious mate- rial, consult your instructor. In 19 97, the American Society for Microbiology, through its Office of Education and Training, adopted the following on laboratory. shill indicates the ratio of a part to a whole; e.g., d means 1 of 2 parts, with a total of 2 parts. A colon indicates the ratio of 1 part to 2 parts, with a total of 3 parts. Thus, d equals 1: 1,