Name
Date
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Introduction:
Robert Hooke was a scientist of many talents. He lived at a time generally recognized as the
beginning of the “scientific revolution.” One of his many contributions was the development
of the compound microscope. Its impact was significant: for the first time, human eyes were
able to see the tiny details of living things, such as the eye of a fly or a bee’s stinger, as well
as other objects previously invisible to the naked eye. In 1665 Hooke published
Micrographia, the first major work on microscopy. It contained many illustrations of
animals, plants, and minerals, and included the results of Hooke’s examination of cork.
Cork is removed from the outer layers of an evergreen species of oak. By making thin
sections of cork and examining it under the microscope, Hooke found it to be full of pores
or, as he called them, “cells.” Hooke’s findings, made possible by the microscope, changed
the way organisms were perceived. Today we use his term cell to describe the basic units of
life from which all organisms are made.
Materials:
Cork from a wine bottle
Sharp knife
Microscope
Slides
Original materials: According to Micrographia it seems likely that Hooke used “raw” cork
from the Quercus suber tree. Cork was first used for sealing glass bottles at about the same
time that Hooke was doing his experiments. The microscope used the same basic principles
as today’s light microscopes and gave a magnification of up to 270x as opposed to the 40x –
400x range with the microscope you are using.
Safety Precautions: Be very careful with sharp tools!! Do not cut the cork while you are
holding it, place it on the lab table!!!
Procedure:
1. Use the razor blade to scrape off a VERY THIN piece of the cork. It must be transparent
in order to see the cells. Make sure it is thin enough that you are able to see light
through the cork.
2. Put the thinnest piece of cork onto the microscope slide. Look at the slide using the
scanning objective. Adjust the light to give the best image.(this is what the diaphragm is
for)
3. You may want to place multiple pieces on your slide to ensure you will be able to find
one that works. Once your slide is secure, move the stage around so that you can find a
good specimen.
Pre-Lab Questions: (all of the answers are contained in this lab paper) Answer all questions
in complete sentences. You may not participate in the lab unless these questions are
complete when you get to class.
1. Why was the invention of the compound microscope important?
2. What is the title of Hooke’s paper and when was it published?
3. What types of illustrations were in Hooke’s book?
4. What did he find when he examined the cork under the microscope?
5. From what tree did Hooke get the cork?
6. What was the magnification on Hooke’s microscope? How is that different from the
microscope you are using?
7. What safety precautions should you use during this lab?
8. If you cut your finger what should you do?
9. What does the underlined word transparent mean? Why is it important for the cork?
10.Are you making a wet mount or dry mount slide? How do you know?
11.What two objectives will you use?
12.On which objective should you use the coarse adjustment?
13.Janssen is credited with the discovery of the microscope in 1590. Why do you think it
took Hooke so long to make his discovery and publish his work?
Observations: Make a sketch of your observations in the space provided below.
Scanning Objective
Low Power
Conclusion Questions: Answer in complete sentences.
1. Describe what you saw under the microscope.
2. Do some research: (look in your cell theory notes and use your noodle) what are the
“cells” that Hooke saw? What part of the cell is it?
3. If you were looking at this for the first time and no one had told you what they were,
what would you have named them? Explain your answer.
4. Can you see a nucleus in the cell? Why?
5. Compare the cork cells to real living cells. How are they different how are they the same?
6. What would you change in the procedure of this lab to make it better? What errors arose
while doing your procedure?