Lens paper is a soft, lint-free tissue paper meant to be used for just such applications. To properly clean the lens with lens paper, wipe in one direction. Microscope Lens Paper is soft, dust-free paper that is used for cleaning microscope slides and lenses without scratching the glass.

Even Q-tips that have only been used once may have dirt on them that could contaminate the methanol and cause scratches in subsequent objectives or oculars when they are cleaned. WHEN LENS PAPER IS USED TO CLEAN OBJECTIVES OR OCULARS, USE A NEW, CLEAN SECTION OF THE PAPER EACH TIME YOU WIPE THE LENS SURFACE.

Terms in this set (19) Why might it be a good idea to keep your microscope at least 10 cm from the edge of the table? Why do you place one hand under the base of the microscope when you carry it? So it’s not at table level and so that people can see it and move out of the way.

NEVER USE BIBULOUS PAPER, KIMWIPES, PAPER TOWELS, OR FACIAL TISSUE ON AN OCULAR OR OBJECTIVE: THEY WILL SCRATCH THE LENS. Cleaning Objectives and Oculars: 1. Gently use canned air to blow away coarse dirt particles.

5. What happens to your image if you try to magnify it using 40x or 100x? It could blow up your iage if you do not adjust the stage accordingly.

Wet-mount Slides A wet-mount slide is when the sample is placed on the slide with a drop of water and covered with a coverslip, which holds it in place through surface tension. Advantages – This type of slide preparation allows you to view microscopic living things without them drying out.

What is the purpose of wet mount? to protect the microscope lens from the specimen and to provide a even surface for viewing.

Wet Mount:

1. Place a drop of fluid in the center of the slide.
2. Position sample on liquid, using tweezers.
3. At an angle, place one side of the cover slip against the slide making contact with outer edge of the liquid drop.
4. Lower the cover slowly, avoiding air bubbles.
5. Remove excess water with the paper towel.

This smaller sheet of glass, called a cover slip or cover glass, is usually between 18 and 25 mm on a side. The cover glass serves two purposes: (1) it protects the microscope’s objective lens from contacting the specimen, and (2) it creates an even thickness (in wet mounts) for viewing.

Possible problems of making a wet mount. The cover glass floats and moves: This is due to too much water. Remove water with the help of a tissue paper. Under no circumstances should there be water droplets on top of the cover glass.

The hanging drop technique is a well-established method for examining living, unstained, very small organisms. The traditional procedure employs a glass slide with a circular concavity in the centre into which a drop of fluid, containing the ‘microorganisms’, hangs from a coverslip.

What organisms can be viewed using a wet mount?

• The organism must be sufficiently thin.
• The organism should have a refractive index which is different from that of the mounting medium (i.e. water).
• The organism should have a color but should not be opaque.
• The organism’s natural habitat should be compatible with the mounting medium.

A wet mount is a living preparation; it consists of a clean slide with a drop of liquid and a cover slip.

How to minimize air bubbles in wet mounts

1. Cover slip placement: Lower the cover slip on the water droplet with an angle.
2. Water placement: If the specimen is not fully submerged in the water droplet, add another droplet on top of the specimen before lowering the cover slip.
3. Immersion oil: Use a medium other than water.

Are wet mounts heat-fixed? NO! Heat-fixing the slide would kill the microorganisms on the slide, and defeat the purpose of using a wet mount.

The wet mount tend to dry out quickly under the heat of the microscope light; it is simpler to perform than the wet mount, but it is useful for short-term observation only. The hanging drop is a more complex technique, but it allows for longer-term obervation and more reliable observation of motility.

In a wet mount, a drop of water is used to suspend the specimen between the slide and cover slip. Place a sample on the slide. Using a pipette, place a drop of water on the specimen. Then place on edge of the cover slip over the sample and carefully lower the cover slip into place using a toothpick or equivalent.

The staining methods we will use kill the bacteria, reducing the risk of infection by pathogenic organisms. Since two dyes are used to distinguish types of bacteria, Gram staining is called a differential staining method. The Gram stain is a direct method, since the cells themselves retain dye.

Principle of Negative Staining The acidic stain, with its negatively charged chromogen, will not penetrate the cells because of the negative charge on the surface of bacteria. Therefore, the unstained cells are easily discernible against the colored background. The practical application of negative staining is twofold.

microscopic observation is that it helps in the identification of the cell by the color change. A disadvantage of staining a specimen is that the stain can kill off the live specimen fairly quickly and can be rather expensive.

True to its name, the simple stain is a very simple staining procedure involving a single solution of stain. Any basic dye such as methylene blue, safranin, or crystal violet can be used to color the bacterial cells.

In a simple staining technique, a positively charged stain colors the negatively charged cells, making them stand out against the light background. In a negative staining technique, a negatively charged stain colors the background, leaving the cells light colored and unstained.

We use nigrosin as our negative stain. This means that the stain readily gives up a hydrogen ion and becomes negatively charged. Since the surface of most bacterial cells is negatively charged, the cell surface repels the stain. The glass of the slide will stain, but the bacterial cells will not.

In staining dyes, nigrosin (CI 50415, Solvent black 5) is a mixture of black synthetic dyes made by heating a mixture of nitrobenzene, aniline, and hydrochloric acid in the presence of copper or iron.

Negative, anionic, or acidic dyes: contain functional groups that have a negative charge. Examples include eosin, nigrosin and Congo red. These dyes are repelled by the negatively charged surface of bacterial cells. Thus, they stain the background, leaving the bacterial cells clear and bright against a dark background.