Sliced Exceeding Thin – Robert Hooke’s Observation of Cells (1635)  (A Great Moment in Microscopy reconstructed by Donald Cronkite and Jewel Reuter)

Robert Hooke was an English scientist who published a book entitled Micrographia in 1635. There he discussed the observations he made with  his microscope, one of the best compound scopes of his day.  In that book, which included observations of a flea, a bee sting, the hinge of a sensitive plant, and many other microscopic phenomena, Hooke tells how he took a piece of cork and sliced it "exceeding thin" and then looked at it under his microscope.  To his amazement, the cork was filled with microscopic pores, which Hooke called cells, perhaps in reference to the cells of monasteries. 

You can repeat Hooke’s observation

 1.  Obtain a cork.  You can do this with a cork from a laboratory, but it is better to use a cork from a wine bottle.  They look more authentic, and they slice better than a lab cork.

2.  Obtain a brand new single-edged razor blade.  Warn students about the sharpness of the blade. 

4.  Put your cork flakes on a microscope slide.  Add a drop of water and then put on a cover slip. 

5.  Compare what you see to Hooke’s picture, reproduced above.  Hooke’s microscope probably magnified no more than 100 – 200 X so keep below that magnification in order to see what Hooke saw.

 Further activities

1.      Do different corks have different sized cells?
2.      Try to duplicate Hooke’s observations exactly.  Take pictures of each student’s result and have a “Hooke’s cells look alike contest.”
3.    Get a copy of Micrographia and look at the other pictures of what Hooke saw.  A reprint of the  book is published by Dover Books.
4.  Do some research to find out what cork is and where it comes from.  Why did Hooke choose to look at cork?

	Donald Cronkite, Biology Department, Hope College, Holland, MI  49423 cronkite@hope.edu Jewel Reuter, Archbishop Rummel High School, Metairie, LA  70001 jewelreuter@earthlink.net