1. Cell Theory
The work of Hans & Zacharia Janssen, Robert Hooke, Anton van Leeuwenhoek, Matthias Schleiden, Theodor Schwann, Rudolph Virchow and others led to the development of the Cell Theory.

2. Hans & Zacharias Janssen 1590
They were father and son team who were Dutch lens grinders. They developed the first compound microscope.

3. Robert Hooke 1665
Hooke was an English scientist. He looked at a thin slice of cork through a compound microscope. He observed tiny, hollow, room-like structures. He called these structures “cells” because they reminded him of the rooms that monks lived in.

4. Anton van Leeuwenhoek 1680
Van Leeuwenhoek was a Dutch fabric merchant and amateur scientist. He looked at blood, rainwater, and scraping from teeth through a simple microscope. He observed living cells and called some of them “animalcules”. Some of the ‘animalcules’ are now called bacteria.

5. Matthias Schleiden 1838
Schleiden was a German botanist. He viewed plant parts under a microscope. He discovered that plant parts are made of cells.

6. Theodor Schwann 1839
Schwann was a German zoologist. He viewed animal parts under a microscope. He discovered that animal parts are made of cells.

7. Rudolph Virchow 1855
Virchow was a German physician. He stated that all living cells come only from other living cells.

8. Current Cell Theory The Cell Theory States:
All living things are composed of cells.
They are made of one of more cells.
Cells are the basic unit of structure and function in living things.
Cells carry out all life activities.
All Cells are produced from other cells.