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1500 BCE
Ancient Egyptians
Ancient Egyptians gained knowledge of human anatomy and preservation through their process of mummification. They removed important organs from the body and learned about the organs and how they worked. They also would wrap up the body to protect it from bacteria and everything else on the outside that would cause it to spoil. This contributes to the cell theory because they understood how the human body is made up of many components "cells" that work together to keep the life form living. -
Period: 1000 to 1500
Medieval Europeans
During medieval times in Europe, many people started to form an interest in biological attributes and began to form questions about the scientific nature of life. Many people started to believe in spontaneous generation and that mice could be “created” spontaneously by putting grain in a dark, quiet place and leaving it for a few weeks. Although this does not directly contribute to the cell theory, it sets up for people in the future to debunk spontaneous generation and develop the cell theory. -
Robert Hooke
Robert Hooke was a scientist from England who studied a kind of tree bark called cork using a microscope. While examining the cork, he notices a bunch of small structures that he named "cells" since they reminded him of the small rooms that monks slept in. Since the cork was dead and dried up, the cells were empty, whereas when they were alive Hooke believed they held water. This contributed to the first part of the cell theory that all living things are made up of cells. -
Francesco Redi
Francesco Redi was an Italian scientist who conducted experiments to support, biogenesis the idea that life comes from other life. His experiment involved a jar of meat that was covered and a jar that was not. Maggots arose in the jar that was not covered due to the flies laying eggs on the meat whereas no maggots of flies were in the covered one. This experiment disproved spontaneous generation and proved that all life comes from other life which connects to the third part of the cell theory. -
Anton van Leeuwenhoek
Anton van Leeuwenhoek was a scientist from Holland who was one of the first to use a microscope to examine cells. Through his microscope, he viewed human cells and samples from pond water. He found bacteria in the sample from pond water and gave moving organisms the name "animalcules". Later on, he observed spermatozoa and concluded how fertilization occurred by sperm uniting with eggs. His observations debunked spontaneous generation and proved that cells come from other cells. -
Lazzaro Spallanzani
Lazzaro Spallanzani was an Italian biologist that believed microbes that spoil food come from the air and could be killed by boiling. To prove this he conducted an experiment that involved two flasks of boiled broth. One that was open and one that was sealed shut. The flash that was open spoiled whereas the flask that was sealed shut did not spoil. This experiment disproved the theory of spontaneous generation and contributed to the cell theory that all cells come from previous cells. -
Jean Baptiste Lamarck
Jean Baptiste Lamarck was a French biologist and one of the best-known early evolutionists. He claimed organisms altered their behavior in response to environmental change. This new behavior, in turn, modified their organs, and their offspring inherited those "improved" structures. He also stated that "nobody can have life if its constituent parts are not cellular tissue or are not formed by cellular tissue." This contributes to the cell theory and that all cells come from pre-existing cells. -
Robert Brown
Robert Brown was a botanist who made many contributions to the understanding of plants and cells. While studying plant cells he recognized a structure within cells. He was able to see small particles moving in and out of a circle-like organelle that was within the cell. He concluded that this organelle was significant for plants to grow and develop. The organelle that he discovered was the nucleus and it is important for all types of cells. This connects to the second part of the cell theory. -
Matthias Schleiden
Matthias Schleiden was a German botanist. He investigated plants through microscopes and found that plants were made up of cells. Schleiden thought that the production of new cells caused plant growth and that the cells came from the nuclei of old cells. From this, he concluded that all plant tissues are composed of cells and that embryonic plants arose from a single cell and that cells are the "basic building block" of all plant matter. This work connects to the third part of the cell theory. -
Theodor Schwann
Theodor Schwann was a German biologist who deeply studied plant and animal tissues which led him to determine that they were made of cells. Schwann concluded three things that became vital components of the cell theory. First, Schwann concluded that both plants and animals were composed of cells. Second, these cells have independent lives. Third, these independent lives are subject to the organism's life. This all contributed to the cell theory in the fact that cells are the basic unit of life. -
Period: to
The Cell Theory
The cell theory consists of three parts:- All living things contain at least one cell.
- Cells are the smallest living units of matter.
- Cells can only come from pre-existing cells.
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Rudolf Virchow
Rudolf Virchow was a German physiologist, physician, pathologist, and anthropologist who was the first to demonstrate that the cell theory applies to diseased tissue as well as to healthy tissue. He observed cells dividing and multiplying under the microscope. Through his and his partner's work he also made the observation that a whole organism does not get sick, only certain cells or groups of cells. His work helped contribute to cell theory and that all cells come from pre-existing cells. -
Louis Pasteur
Louis Pasteur was a French biologist who discovered pasteurization. He conducted an experiment in which he boiled broth and examined how it changed in flasks with different-shaped necks. In the flask with the straight neck, the broth became contaminated whereas in the flash with the curved neck the broth did not. Germs were able to fall right into the straight-neck flask. This experiment disproves the notion of spontaneous regeneration. This showed how cells can only form from existing cells. -
How does the formation of the cell theory over time illustrate the nature of science?
The formation of the cell theory over time illustrates the nature of science because the scientist used empirical evidence to support their scientific knowledge. They used the data from their experiments to back up their theories. It also illustrates the nature of science since scientific knowledge is open to revision in light of new evidence. Prior to all of these scientist, people believed in spontaneous generation, but they disproved this theory with their new evidence from experiments.