M EET THE S CIENTISTS : D EVELOPING THE C ELL T HEORY
W HAT IS A CELL ? The cell is the basic unit of structure and function in living organisms, including plants and animals.
A LL LIVING THINGS ARE MADE OF CELLS Plants Animals
T OOL USED TO VIEW CELLS The microscope is used to magnify extremely small objects.
T IMELINE Hans and Zacharias Janssen (1590) Dutch lens grinders Father and son Produced first compound microscope (two lenses)
T IMELINE Robert Hooke (1665) English scientist Looked at a thin slice of cork through a compound microscope and observed tiny, hollow room-like structures He called them cells, but he only saw the outer cell walls because the cork cells were not alive.
T IMELINE Anton van Leeuwenhook (1680) Dutch amateur scientist Looked at blood, rain water, and scrapings from teeth through a simple microscope. He called the structures he saw “animalcules”.
T IMELINE Matthias Schleiden (1838) German botanist Viewed plant structures under a microscope and discovered that they were made of cells
T IMELINE Theodor Schwann (1839) German zoologist Viewed animal tissue taken from animal organs under a microscope and discovered the tissue was made of cells
T IMELINE Rudolph Virchow (1855) German physician Stated that living cells come only from other living cells (This is a part of cell theory.)