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2600 BCE
Ancient Egyptians
The ancient Egyptians, from around 2600b.c., had already gained a basic knowledge of human anatomy through their common practice of mummification. When the Egyptians removed major organs from the soon-to-be mummies they learned how major organs functioned. The extent of Egyptian scientific discovery is to understand that the human body is made up of many components, all working together, which is a part of the second principle of the cell theory. -
Period: 2600 BCE to
The Cell Theory
Three Principles
-All living things contain at least one cell
-Cells are the smallest living units of matter
-Cells can only come from pre-existing cells -
1200
Midieval Europeans
Europeans had begun to develop an interest in biological attributes through various living things. People began to question the nature of life. They believed that mice could be “created” spontaneously by putting grain in a dark, quiet place and leaving it for a few weeks. The earliest ideas of the cell theory trace back to this time. -
Robert Hooke
Hooke was one of the first scientists to embrace the use of early microscopes. Hooke designed his own light microscope to examine multiple different organisms. When using his microscope he saw, "tiny boxlike cavities". He then described them as cells, and they ended up being plant cells. Hooke’s discovery led to the understanding of cells as being the smallest units of life. Which is one of the main points of the cell theory. -
Francisco Redi
Redi wanted to disprove that life did not spontaneously occur as it did with maggots on meat. To disprove this he left out a jar of covered meat and a jar of uncovered meat, later finding maggots only on the uncovered meat. In short, Redi determined that living organisms come from other living organisms-which later became the 3rd principle of the cell theory. -
Anton van Leeuwenhoek
Leeuwenhoek was able to design a microscope that was able to magnify up to 270x with a single lens. With this microscope, he was able to discover bacteria and called them "animalcules" or "little animals". No one else was able to see these things besides Leeuwenhoek. Leeuwenhoek's contributions help to form the second principle of the cell theory. He discovered single-cell organisms which led to the creation of the principle that cells are the basic unit of life. -
Lazzaro Spallanzani
Spallanzani followed in previous scientists' footsteps and helped disprove spontaneous generation. He used an experiment that used boiling gravy to help conclude that Leeuwenhoek's findings were correct, thus contributing to the third principle of the cell theory. -
Jean Baptiste Lamarck
Baptiste suggested that organisms change over time. He specifically suggested that over time organisms got more complex over time. He theorized that over time single-cell organisms would evolve into multicellular organisms. In addition, he observed that organisms changed their behavior in response to environmental change. This contributes to the third principle of the cell theory because new cellular organisms come from previous ones when they adapt. -
Robert Brown
Brown was famous for his discoveries in plant cells. Brown was the first person to discover the nucleus in cells. He originally believed that they were exclusive to plant cells. He described the nucleus as distinct and that it always rested at the center of the cell. These findings contribute to the second principle of the cell theory because it helps further our knowledge of cells and that they are the basic organizational structures of life. -
Theodor Schwann
Schwann was one of the key scientists in developing the cell theory. He studied the plant and animal tissue cells to help improve the cell theory. He combined the theories and ideas of previous scientists to conclude that plants and animals were made of cells. He also concluded that cells have independent lives and their independent lives are subject to the organisms' life. This helped form the first two principles of the cell theory. -
Matthias Schleiden
Schleiden was one of the main founders of the cell theory. He worked with Theodor Schwann to help develop it. He originally theorized that cells are made up of cells. Later, Schwann added to his theory when he discovered cells also make up animals. He discovered the importance of the nucleus in the cell. He recognized the cells as the fundamental units of life. This helped to develop the 2nd principle of the cell theory. -
Rudolf Virchow
Virchow was one of the biggest contributors to the cell theory. He discovered that individual organisms don't get sick. He discovered that groups of cells are the ones that get sick. He later discovered cell division which helped form the third principle of the cell theory, that all cells come from pre-existing cells. -
Louis Pasteur
Pasteur's most notable achievement was proving evidence against spontaneous generation. He also discovered that illnesses did not come from the inside of the body but rather from germs outside the body. This helps prove that all cells come from previous cells. -
Nature of Science
When creating the cell theory, the nature of science is a huge factor. Many scientists based their claims on empirical evidence. For example, Redi used his evidence from the maggot experiment to disprove spontaneous generation. Throughout the entire creation of the cell theory, it was revised many times in light of new evidence. For example, Europeans believed that life would just appear after a while. This was later disproved by Redi and various other scientists.