Category: January, 2010

Observing bacteria under the light microscope

It is possible to use non-toxic stains (such as ink for fountain pens) to stain yogurt bacteria in-vivo.

Making a wet mount for microscopy

A wet mount (or temporary mount) is one of the most common ways of observing specimens under the microscope. The sample to be viewed floats in a layer of water which is between the slide and the cover glass. The water performs an important optical function. Without it, the resolution is lower. The general procedure [...]

Making mounts of pollen grains

Permanent slides of pollen grains can be used as a reference for identifying unknown pollen samples. It is therefore important, that the pollen grains remain in an authentic, natural shape. The preparation and mounting of the pollen can introduce artifacts: the pollen may lose some of its pigment, start to shrink and shrivel or absorb [...]

Required camera resolution for photography through the microscope

My digital camera (a Canon EOS 450d) is capable of taking pictures at 3MP, 6 MP and 12 MP (MP=megapixels). Which setting should one choose to obtain the optimum results? If the camera resolution is too low, then this will result in the loss of image detail (but a small file). A resolution setting which [...]

An overview of mounting media for microscopy

Mounting media are needed for making permanent slides. The mounting medium holds the specimens in place between the cover slip and the slide. The choice of the right mounting medium is a separate topic all on its own. There are countless commercial and home-made mounting media available. Which ones should one use? In many cases [...]

Choosing the right mounting medium for making permanent slides

There are numerous different mounting media available for making permanent slides. What factors determine the choice of the mounting medium? Here are some possible points to consider. Toxicity: Solvent-based mounting media (such as Eukitt and Canada Balsam) require the specimen to be in xylene prior to embedding. This substance is toxic. Other mounting media, such [...]

Different types of microscopes

How many different types of microscopes are there? More than you probably thought. I tried to research a list of different types, based on the physical principle used to make an image. Of course, one could also classify the microscopes based on their area of application, their cost, their versatility or any other aspect. These [...]

Taking stable photographs with a microscope

Specimens which are suspended in water are not completely immobilized. Small objects will start to vibrate when one is tapping on the table on which the microscope stands. The optics of the microscope will magnify even the smallest vibrations. These vibrations become problematic when taking pictures with a photo camera which is mounted directly to [...]

Staining bacteria

Here is yet another link to an article from Popular Science magazine. It deals with the isolation, fixing and staining of bacteria. I would not recommend the use of some of the solvents that they use (such as xylol) with children, however. They also describe a blood smear preparation, what I do not recommend for [...]

Virtual microscope: dandelion parachute

This the the parachute of a dandelion seed. The seed is not shown, it is attached to the long extension on the right. The leaves of the plant are toothed. The name “dandelion” comes from the French “dent-de-lion” meaning “lion’s tooth”. The microscopic observation reveals that the leaves are not the only part of the [...]