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Period: 350 to
Cell Theory
- All organisms are made of cells.
- All existing cells are produced by other living cells.
- The cell is the most basic unit of life.
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400
Aristotle
Approximately 384 B.C.
Performed countless experiments and dissections. He proposed spontaneous generation(living organisms arise from non-living matter). These dissections led to his discoveries of life and basic classifications. Among the first to theorize that a mother and father contribute genes/biological material towards offspring, which leads to "existing cells come from other cells." He also demonstrates this through his basic knowledge that there are connections between every organism. -
400
Ancient Egyptians
Approximately 1500 B.C.
By this point, the Ancient Egyptians had a fundamental understanding of human anatomy through mummification. Through the mummification process, they developed a key understanding of organs and how they work. Their contribution in relation to cell theory is the understanding that the human body is made up of many different parts which work together, which relates to "all existing cells are produced by other living cells." -
400
Medieval Europeans
5th-15th Century
Began to look at the nature of life and its biological attributes. Even though society was much more focused on agriculture and the study of plants during these years, many began to question the world and dig deeper through a scientific perspective. Biology and its beginnings can be traced back to this time, which also intern connects the cell theory to this time. -
1543
Andreas Vesalius
Vesalius was a physician who studied the anatomy of humans through dissections, and cadavers. His book "The Fabrica" is widely considered to be one of the first books on anatomy ever published, and is one of the most influential and important anatomies ever published. His work showed how cells function together to form the complex organs and systems needed to survive, which therefore demonstrates that "cells are the basic unit of life." -
Hans and Zacharias Janssen
Hans and Zacharias were the inventors of the first compound microscope. This allowed scientists who followed in their footsteps to observe cells as they improved on their invention. This observation of cells allowed scientists to deduce that "all organisms are made of cells." -
Robert Hooke
Hooke was the first person to truly discover cells. He noticed box-shaped structures when looking at cork under the newly created microscope, he named these boxes "cells." This led to the creation of the cell theory as he discovered the thing it describes, "all organisms are made of cells." -
Francesco Redi
Redi famously sought to disprove spontaneous generation. He is quoted as saying "Omne vivum ex ovo" or "All life comes from an egg." He proved this with an experiment where he left a jar with covered meat and uncovered meat, and he found maggots and flies in the uncovered jar not the covered. This proved life does not appear out of nothing, rather it comes from the outside world, "existing cells come from other cells." -
Anton Van Leeuwenhoek
Invented lenses that could magnify up to 270 percent. This powerful microscope helped him discover spermatozoa which explained reproduction, he was also the first to see bacteria and protozoa. He was known as "the father of microbiology." His creation allowed him and the scientists that followed to study cells and find evidence of the cell theory, therefore he is essential in the creation of the cell theory itself. -
Lazzaro Spallanzani
Spallanzani disproved spontaneous generation and corrected John Needham's broth experiment, Needham thought his experiment proved spontaneous generation to be possible but Spallanzani disproved this by using proper procedures and boiling techniques. His results proved spontaneous generation to be false and aligned with the second part of the cell theory "All existing cells are produced by other living cells." -
Jean Baptiste Lamarck
Lamarck recognized that all living things were made of cells, he fostered the theory of inheritance of acquired characteristics, sometimes referred to as Lamarckism. Found that "something" was passed down from parents to their offspring. Contributed to the theory of evolution, found changes in organisms were caused by the environment and passed down through generations. -
Robert Brown
Botonist who observed plant cells, his studies led him to discover and name the cell nucleus. He helped develop and contribute to the cell theory as he keyed in on the nucleus and its significance as a vital part of living cell structure. -
Matthias Schleiden
Looked at plants on a microscopic level, and concluded all plant tissues are composed of cells, and embryonic plants arise from single cells. Stated cell was the basic building block of plants. Believed plants grew through the production of new cells, basically all of his beliefs align and contribute to the cell theory. Co-founded the cell theory along with Schwann. -
Theodor Schwann
Concluded the same things as Schleiden except in animals rather than plants. Put to rest the debate that animals and plants were on a fundamental level different. He examined the cell structure of animals and concluded that "cells are the basic unit of life." Co-founded the cell theory along with Schleoden, put countless scientific findings of cells into the theory. -
Rudolf Virchow
Strengthened the cell theory and the idea that cells come from other cells. He published his famous aphorism “omnis cellula e cellula” (every cell stems from another cell). He was the first to demonstrate cell theory applied to healthy and diseased cells. -
Louis Pasteur
Conducted an experiment to end the debate of spontaneous generation once and for all. Used a swan neck-shaped flask beaker to trap microorganisms and prevent them from entering the meat broth he was boiling. The shape kept any particles from reaching the broth while allowing air to flow in, the broth was completely free of anything. However, as soon as he tipped the flask and allowed everything to flow in without being trapped the broth became cloudy. Proved cells are formed from other cells. -
"The Nature of Science"
The formation of the cell theory is a shining example of the true nature of science. It shows how science is a process of development, partnership, and refinement. It shows how knowledge changes over time based on the discoveries of others. The cell theory has become a key part of biology and is a prime example that knowledge in science is never a static thing, it is ever-evolving and ever-changing.