Cell Theory Timeline

Zacharias Jansen

Jan 30, 1595

Credited as the first person to build a compound microscope, his invention would enable the discovery and study of the cell. The fact that all living things are made of cells is the unifying concept in biology because it shows how all living things are similar to each other.

Robert Hooke

Sep 1, 1665

Hooke publishes his book Micrographia which contains his drawings of sections of cork (plant matter) as seen through one of the first microscopes. He calls the tiny, rectangular chambers that he sees "cells", after the name for the small, plain rooms found in a monastary.

Anton Van Leeuwenhoek

Sep 7, 1674

Leeuwenhoek observes microorganisms in pond water using his simple microscope. While not the first person to see cells, he is credited as the first to observe actively living cells.

Matthias Schleiden

Jan 31, 1838

Schleiden was a microscopist who studied plants and determined that all plants are made up of cells. He consulted with Theodor Schwann, who was studying animals. Together they determined that all living things were made up of cells, one of the main components of the cell theory.

Theodor Schwann

Jan 31, 1839

Schwann was a microscopist who studied animal tissue and determined that animals are made up of cells. He consulted with Matthias Schleiden, who was studying plants. Together they determined that all living things were made up of cells, one of the main components of the cell theory.

Rudolph Virchow

Jan 31, 1855

Virchow developed the field of cellular pathology, or the study of how disease affects cells and tissues. He concluded that "every cell stems from another cell", essentially identifying that cells are produced by the division of existing cells. This discovery completed the cell theory.

Julius von Sachs

Jan 31, 1864

Sachs is credited as the first plant physiologist. He studied the structure and functions of plants extensively during his lifetime. In 1864, Sachs published a paper describing how using a high powered microscope, he observed that starch granules were assimilated by the chloroplasts in a plant's leaf, evidence that the chloroplast was the site of photosynthesis in plants.

Richard Altmann

Jan 31, 1890

Thanks to higher powered microscopes, scientists like Altmann were able to study the structures inside the cell. Altmann was a German pathologist who discovered mitochondria, structures inside of eukaryotic cells that convert food into cellular energy.

Lynn Margulis

Jan 31, 1970

Margulis, an evolutionary biologist, discovered that chloroplasts and mitochondria have DNA, leading her to propose the idea that eukaryotic cells arose from smaller, simpler prokaryotes living symbiotically inside one another. The endosymbiont theory suggests that chloroplasts and mitochondria were once free living organisms.