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Hans and Zacharias Janssen constructed the first compound microscope
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The invention of the compound microscope led to more discoveries.
Marcello Malpighi by looking at frog lungs and live fish through the microscope, he observed structures that looked like corpuscles (today we know they are red blood cells) traveling through what we know today are capillaries -
Robert Hooke 1665
Using his microscope, Hooke observed structures that looked like tiny boxes in bark from an oak tree. He called these cells. -
In 1833, Robert Brown discovered the nucleus through observations in orchid cells. Later discovered that nuclei were also found in all other plant cells
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Matthias J. Schleiden through observations in plant tissues under the microscope discovered that all plants were composed of “cells”
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Theodor Schwann, a friend of Matthias Schleiden, concluded that not only plants but also animals were composed of cells
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Felix Dujardin reported that cells were not empty but contained a clear jelly-like fluid that he called protoplasm (he was working with amoeba) but now we know this as cytosol
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Rudolf Virchow discovered bacteria living in intestines. He also discovered cell division. He is one of the scientists that also proposed that cells come from pre-existing cells
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Robert Remak discovered cell membrane by developing a method to isolate it from the cell and he proved that it divides cell.
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Rudolph Virchow
The observations of Matthias Schleiden, Theodor Schwann, and Virchow were combined and became the "Cell Theory." According to this theory, cells are the basic unit of life, and all living things are composed of cells derived from previous cells, and life does not appear by spontaneous generation.
Rudolph Virchow concluded that all cells come from other living cells. -
Walther Fleming stained cells with dyes and he discovered what we call today chromosomes
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Oswald T. Avery announced that DNA alone is the substance responsible for heredity
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Francis H. C. Crick and James D. Watson made a model of the DNA molecule and proved that genes determine heredity and determined the chemical structure of DNA
