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Exercise 1.   The Discovery of Cells

A. Introduction


Ancient Greek philosophers famously espoused the idea that life generated spontaneously. Aristotle recognized that some animals come from parent animals of the same kind, but thought that others appear spontaneously from a nonliving substance he called pneuma and from four terrestrial elements, earth, air, fire and water. Aristotle condensed these ideas into a theory that we now call the Theory of Spontaneous Generation. The theory basically states that living organisms form spontaneously, from nonliving matter.

It wasn't until the 1800s that scientists made the important discoveries that unequivovally dispelled the theory of spontaneous generation. One of these developments was the formulation of the Cell Theory. The Cell Theory, one of the fundamental unifying principles of biology, establishes the cell as the basic unit of life. As is summerized in the timeline below, the theory grew out of hundreds of years of scientific research and technical developments, beginning with the development of glass lenses and the microscope and continuing with the discovery of the cell. In this exercise, we trace some of the major events in the history of the development of the microscope, discovery of the cell and the formulation of the cell theory. In lab, we microscopically examine some of the same specimen early biologists examined when they first observed cells and finally came to the conclusion that all living things are made of cells.

Timeline highlighting some of the major scientific and technical developments leading to the formulation of the Cell Theory.