13
slide and place to the microscope stage.
Observe the slide and write down your observa-
tions. You will see hundreds of starch grains.
Take a few kernels from an uncooked ear of
corn. Scrape off some shavings and make a
smear as you did with the potato. Compare how
the corn is different from potato. Create smears
of other foods such as apples, bananas, peach-
es, and pineapples. You will observe that these
items have membranes rather than starch.
To save your slides, put gum media on a clean
dry slide and then position your specimen in the
media. Place a cover slip over the media and
attach a label.
Before you make a permanent mount, you may
wish to stain the specimen first.
Staining Smears
Not all specimens are easily observed in the
microscope. Staining specimens make them
easier to see. Staining is not difficult, but it does
require care. It is recommended that you keep
paper towels nearby as the process can be
messy.Before you prepare the smear, you will
need to prepare the eosin. See note at the left.
First, create a fresh smear (you may use shav-
ings from an apple or other piece of fruit), as
described previously. Do not place any water or
a cover slip on the specimen. Set the slide aside
to dry, if necessary.
When the slide is dry, use the eyedropper to
place one drop of eosin (
F, Fig. 1) on the slide.
From the cup labeled flush, draw up water into
the eyedropper. Dispose of the water into the
cup labeled waste. Perform this operation a few
times to clean out all the eosin from the eye-
dropper.
Tilt the slide from side to side to spread the stain
over the specimen. Remove the excess fluid to
the waste cup. Put down the slide and wait about
two minutes.
To flush away the excess stain and to stop the
staining action, hold the slide at an angle over
Note:
In order to stain a
slide, you will need
to prepare the
eosin:
Without opening
the container, look
closely at the
container marked
“Eosin (
F, Fig. 1).”
You’ll notice a few
grains of ‘dust’ at
the bottom of the
container. These
are the grains of
eosin. Remove the
container’s lid and
use the eye
dropper (
N, Fig. 1)
to fill the containe
with water. Gently
stir the mixture.
You have now
prepared the eosin
for use.
