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400
Ancient Greeks
Approx. 4th Century B.C.
Started the technique of the scientific inquiry. Originally philosophers, the Greeks followed steps to answer questions with a hypothesis, and an experiment with accurate recordings of observations, then, proceeds with logic and interpretation to find an answer to the question. -
Hans and Zacharias Janssen
Approx 1595 - 1610
Hans and Zacahrias Janssen – Invented the microscope with ocular lenses and an objective lens. A compound microscope was created, the invention was an important advance from single lens magnification (magnifying glass). His microscope had a 3-9x power of magnification. This furthered biology, and the study of cells.” It is rumored that his father, Hans did help with the invention. -
Antoni van Leeuwenhoek
– Noted for his subsequent contribution to microbiology. He used a simple single-lens microscope to discover single cells, such as blood, insects, and many other objects. He was the first to witness the different cells’ movements, and describe them. Originally, he had named these unicellular organisms ‘animalcules (now known as microorganisms) Though his microscopes were small, the lenses also had a higher magnification than that of the compound microscope. -
Robert Hooke
Studied various objects with a hand-made compound microscope. He then, published his results in Micrographia, containing the 38 illustrations of animals, plants, and other objects. Among this work were the characteristics of cork, and its properties of ability to float in water. He named the empty chambers, cells. -
Francesco Redi
Did not believe in spontaneous generation, and experimented with meat to prove his theory. Despite the evidence, the idea of spontaneous generation continued. This discovery was the important factor in discovering that cells can only come from other like-cells. -
Robert Brown
Observed a small blob inside of the orchids he was studying. He called this sphere in the cell, the nucleus. He revealed the nucleus of cells, and started the idea that all cells contain nuclei. Also, he was the first to declare that the nucleus is important to a cell’s proper functioning. -
M.J. Schleiden
Concluded that all plants are made of cells, and that an embryo is made from a single cell. He recorded his observations of plant tissues under the microscope and concluded that plants were made of cells -
T.S. Schwann
Schwann had proved the cellular origin and development of different tissues, skin cells, hair, and other cells. His discoveries were much similar to that of Schleiden’s about plants. Schwann described animal cell structures. His observations concluded that cells are organisms, and all organisms consist of one or more cells. Also, that the cell is the basic unit of life. His generalization of the cell had become the most important part of the history of cells, known as the cell theory. -
Rudolf Virchow
Virchow was the first to observe the fact that an entire organism does not get sick at once, but rather only a certain group, or cell. His famous aphorism, or Latin phrase, was “omnis cellula e cellula” which means, every cell stems from another cell”. -
Louis Pasteur
Completed experiments to find where bacteria come from, and were able to prove that the germs and bacteria were found in the dust particles within the environment. He demonstrated that microorganisms, such as bacteria would only grow in broths that were opened to air. With this, he declared that microbes do not generate out of nowhere, that spontaneous generation is not possible. As well, Pasteur showed that although microorganisms live almost everywhere, the spread of them can be controlled.
