Use your low power objective and get the specimen in focusjustat the
edge of the cork slice where it is likely to be the thinnest.
You will observe:Tiny empty"boxes"with stiff walls.
! itllJ\ 7
These"boxes"arecells. Everything living is composedofeither one cell
orofmany cells,containinglivingmattercalledprotoplasm. This is a thick,
jelly-like fluid, and it is the physical basis of all life. But since the livingmatter
ofthecorkhas died, its cells are empty. They no longercontainthemiraculous
and still somewhat mysteriousprotoplasm.
Inadditiontoprotoplasmall cells have anucleus,a denseroundstructure
usually in the middle. This is the"heart"and"brains"of the cell, for it directs
allofthe cell's activities. A cellcannotlive, nor can it divide or reproduce
itself,withouta nucleus.
LIVING PLANT CELLS FROM AN ONION SKIN
Materials: Ask yourmotherfor a smallparingknife and permission to
useit. Get a small piece of fresh onion, a medicinedropperand mix asolution
of iodine and water, called "diluteiodine."
Follow this procedure:With the medicinedropperplace adropof dilute
iodine in the middle of the glass slide. With theparingknife, carefully peel off
a tissue-thin layer from the top piece of onion. Place this in the drop of iodine
on the slide. Carefully put the cover slip over it.
Place thepreparedslide on the stage of your microscope. Observe first
with low power, and then with high power.
You will observe:Manyrectangularboxes. These are the building blocks
ofall living plants andanimals-thecells.