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Observing
in Biology
Many of the interesting things in biology are very small and delicate. Our eyes need help to be able to see them properly. Our fingers are too big so we need tools to handle them carefully. Picking up small specimens If they are solid use forceps, do not use your fingers.
If they are in water use a dropping pipette.
Observing Small Specimens First of all make sure that you have enough light. Use a bench lamp.
Using a hand lens This magnifies about ten times; we write X 10.
Keep the lens
close to your eye (about 8 cm). Bring the specimen that you
are observing up to the lens or bend down to look at the
specimen.
Using a binocular microscope The binocular
microscope usually magnifies by x20. We use both eyes which
gives us a clear three-dimensional view.
First choose the background that you want to use. A dark specimen is more easily observed against a white background and a pale specimen is more easily observed against a black background.
Put your specimen under the microscope and illuminate it with a bench lamp. Raise the microscope until you can see the specimen approximately in focus. Now lock the microscope in place. Finally focus precisely, using the focusing knob.
You may also find that the eye-pieces of your binocular microscope are too far apart or too close together. These can be moved to suit your eyes. |
© Shirley Burchill 2007 |
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