CHAPTER 14 Ten Basic Experiments 87
Ouch! – Blood Smear
This experiment is not good for weak nerves. But you also don’t have to be Dracula’s
little brother ;o). Human blood appears to be a red liquid to the naked eye,
but under a microscope you can see that it contains several elements. The plasma
is the liquid part of blood, and is actually colorless. The red blood cells give
blood its red color. White blood cells are interspersed in the sea of red blood cells
and help fight infection. The smaller platelets are fragments of red blood cells and
function in clotting.
You need:
✔✔A glass slide with coverslip
✔✔A pin
✔✔Blood
Sterilize the pin by running it through a flame. Poke your little finger,
squeeze it, place a drop of blood on a slide and cover with the coverslip.
Gently wipe the edge of the coverslip over the blood and produce
a smear. Now cover with the coverslip. Place the slide on the
microscope stage and increase magnification until you see the components
of blood:
✔✔Plasma
✔✔Red blood cells
✔✔White blood cells
✔✔Platelets
Due to safety issues people from laboratories normally don’t use their
own blood. But maybe you can find a volunteer?
Yogurt Bacteria
Yogurt is produced by bacterial fermentation of milk. Such bacteria are beneficial,
keeping us healthy and helping us to digest our food. Why not have a look to
see if some of these yogurt cultures are visible?