Cell Theory Timeline
Timeline Description: Before 330+ years ago, there was no knowledge of cells. Cells were too small to be seen. But with the invention of the microscope, an entirely new world was discovered, where very large objects like humans are in fact made up of billions of tiny individual pieces called cells.

Date Event
1665 Cell first observed

Robert Hooke, an English scientist, discovered a honeycomb-like structure in a cork slice using a primitive compound microscope. He only saw cell walls as this was dead tissue. He coined the term "cell" for these individual compartments he saw.
1670 First living cells seen

Anton van Leeuwenhoek, a Dutch biologist, looks at pond water with a microscope he made lenses for.
1683 Miniature animals

Anton van Leeuwenhoek made several more discoveries on a microscopic level, eventually publishing a letter to the Royal Society in which he included detailed drawings of what he saw. Among these was the first protozoa and bacteria discovered.
1833 The center of the cell seen

Robert Brown, an English botanist, discovered the nucleus in plant cells.
1838 Basic building blocks

Matthias Jakob Schleiden, a German botanist, proposes that all plant tissues are composed of cells, and that cells are the basic building blocks of all plants. This statement was the first generalized statement about cells.
1839 Cell theory

Theodor Schwann, a German botanist reached the conclusion that not only plants, but animal tissue as well is composed of cells. This ended debates that plants and animals were fundamentally different in structure. He also pulled together and organized previous statement on cells into one theory, which states: 1 - Cells are organisms and all organisms consist of one or more cells 2 - The cell is the basic unit of structure for all organisms
1840 Where does life come from

Albrecht von Roelliker discoveres that sperm and eggs are also cells.
1845 Basic unit of life

Carl Heinrich Braun reworks the cell theory, calling cells the basic unit of life.
1855 3rd part to the cell theory added

Rudolf Virchow, a German physiologist/physician/pathologist added the 3rd part to the cell theory. The original is Greek, and states Omnis cellula e cellula. This translates as all cells develop only from existing cells. Virchow was also the first to propose that diseased cells come from healthy cells.