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Period: Jan 1, 1500 to
Cell Theory Timeline
The three main principles in the Cell Theory:
- all organisms are composed of one or more cells
- cells are the smallest unit of life
- all cells came from pre-existing cells -
Hans and Zacharias Janssen: invented the first compound microscope
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Robert Hooke: discovered the cellular composition of cork
First described cells while observing cork with a microscope he built himself. -
Anton van Leeuwenhoek: "animacules" were discovered
"animalcules"= living cells ("little animals") -
Anton van Leeuwenhoek: discovered bacteria
discovered bacteria by using a sample of saliva from his mouth -
Robert Brown: discovered the nucleus of cells
He stresses its importance in fertilization. -
Matthias Schleiden: stated that plants are made up of cells
He called the cells "independent, separate beings" -
Theodor Schwann: stated that animals are made up of cells
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Wilhelm Hofmeister: mitosis in plants
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Rudolph Virchow: stated that all living things come from other living things
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Louis Pasteur: proved that all cells come from pre-existing cells using sterilized chicken broth
After sterilizing chicken broth by boiling, he showed that living organisms would not "spontaneously" reappear. Only after exposure to pre-existing cells was life able to re-establish itself in the sterilized chicken broth. -
Ernst Ruska: constructed the first electron microscope
