microscope kits specially designed for children are available.
These can provide a good introduction to science in general and
microbiology in particular. Kits often come with books of
experiments and the necessary accessories to do them, including
stains and slide making sets. With this little plastic microscope
it is possible to see cells structure, protozoa and algae filaments.
open the door to the world of Microbiology. Special microscopes
for use by student of all ages are available from science equipment
suppliers. These are about the same cost as a good quality
camera, and will be in the price range of keen individuals and
most schools. Ideally the microscope should have a magnification
of at least X50. This should enable you to see detail in
cells and protozoa.
look at bacteria and smaller microbes a magnification in excess of X500
Bacteria on a pin head. (Left) X100 (Right)
© 1999 The Centre for Microscopy and Microanalysis
are a five small projects that you can do if a microscope is available.
Take sensible precautions such as washing hands
after handling soil and pond water. Do not put these substancesin
your mouth. If you allow bread to go moldy, keep it away from other
food and dispose of it safely after your examination. And again,
wash you hands.
will find the following accessories helpful:
You will need to learn how to focus and how to
adjust the light on your microscope. Lighting is very important
right can make all the difference to your view. You will get the
hang of it by trial and error. The instruction booklet with the
microscope may help you master the basics, if not then your teacher
may be able to help. Or you may even find that your parents may
know what to do....
some microscopes it is possible to change the magnification. Experiment
with this. You will soon learn though, that the biggest magnification
doesn't always give the best view, though!
1: The Leaf and Cell
Robert Hooke, the seventeenth-century
British scientist, is credited with being the first person to use
a microscope for serious study. He built his own microscope
in 1662 and three years later, in his paper Micrographia,
described his observations. One of these was the discovery
of the organic cell.
observed the first cell in cork-bark, and produced drawings of the
cell structure that he saw. You can repeat his experiment,
but use leaves instead of cork.
a fresh leaf from a tree and a dead leaf (from the same tree) from
the ground look at. Look at each in turn under the microscope.
Depending upon the type of microscope you are using you may be able
to simply place the specimen on the viewing stage and look at it.
If the view isn't good enough, make a microscope slide
of your specimen.
what you see using colored pencils. Can you see any differences
between the live and dead leaves? Draw them and indicate them
on your drawings. Start with a magnification of X50 or X100
if you can change the power of the microscope.
let us look at the leaf cell.
A higher magnification may now help see more detail. Draw
the cell you are looking at.
you identify the following: The cell wall. The Nucleus. The
collect samples of water from outdoors (eg a puddle, a stream
or a pond) or from different depths in tropical fish tank.
If it is dirty all the better, but be sure to wash your hands
after collecting it and after doing the experiment. Label each,
recording the origin and date collected.
Protozoa: Ameba (magnified)
a drop of water from a sample onto a glass microscope slide with
an eye-dropper and examine it through the microscope. Identify
what you see. The images above and below may help.
Algae: Spirogyra (life size)
may be able to identify protists (protozoa) and algae in the water.
They may be alive
and moving. If they move too fast add some gelatin to the
water to thicken it and that will slow them.
a piece of bread to go moldy you can examine the minute fungal spore-caps
under the microscope. These are raised on tiny stalks, just
as with mushrooms. The spores are released into the
atmosphere from time to time and these are the "seeds" of new fungal
colonies. They drift and settle. If the material they
settle on is damp and/or organic a new fungal colony may appear.
should also be able to see the hyphae, which are thread-like structures
that spread throughout the moldy areas, linking the stalks.
These hyphae burrow into the bread like plant roots. They
excrete enzymes that dissolves the bread, and the resulting goo
is re-absorbed by the mold as food.
(Left) Bread mold spore X500
(Right) Mold on chopped tomatoes. (life size)
(Left) © 1994, The Centre for Microscopy
and Microanalysis (Right) S Hodges, 2000
4: Making Microscope Slides
a microbiologist will need to keep a permanent sample and record
of his or her work. This can be done by making a microscope
slide or mount. You can make dry or wet mounts,
depending on the type of specimen and its environmental medium.
Dry mounts can be retained almost indefinitely and can be made as
The specimen is put on the center of a small rectangular
piece of glass and then sealed with a clear plastic adhesive membrane
(available in packets).
a wet mount can be made by squashing a specimen between two pieces
of glass with a water or another liquid medium. The edges
of the glass can then be held together with tape if necessary, though
most temporary wet mounts should stay together by surface tension
effects of the liquid.
5: Revealing Stains
microbiologist may need to improve the clarity of what is being
studied though the eyepiece, so the technique of staining a specimen
can be applied. Sometimes specimens are so thin no detail
can be seen. They are almost transparent.
Specimens can be stained to enhance their clarity, so they stand
out more easily when viewed. Different parts of a specimen
will absorb the stain at different rates, so some parts will be
more colored than others, which will help you to see more detail.
specimens will need different amounts of stain and different staining
times. Apply the stain in small quantities with an eye-dropper.
Leave it for around half a minute then soak up excess with blotting
paper. Trial and experience will help you to learn how much
stain to use and how long to soak a specimen.
types of stain are available, and these can be obtained from science
equipment suppliers or pharmacies ( for example Fuchsin, Eosin and
Methylene Blue). Fuchsin is probably the easiest to use.
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