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Feb 2, 1500
Spontaneous theory
Prior to the seventeenth century, biologists developed a theory the ‘theory of spontaneous generation’—that some animals such as worms and frogs could spontaneously emerge from mud or water, and that organisms such as maggots developed from rotting meat. However, the Italian scientist Francesco Redi showed that maggots developed only on meat that flies had laid their eggs on. -
First compound microscope
Dutch technicians developed the art of grinding glass lenses and the first compound (two lens) microscope was made by Hans and Zacharias Janssen. -
Cell first observed
Robert Hooke, an English scientist, discovered a honeycomb-like structure (tessellated) in a cork slice using a compound microscope. He only saw cell walls as this was dead tissue. He coined the term "cell" for these individual compartments he saw. -
First living cells seen
Anton van Leeuwenhoek, a Dutch biologist, looks at pond water with a microscope he made lenses for. -
Microorganisms spotted
A Dutch lens grinder and microscope maker, Anton van Leeuwenhoek, saw microorganisms under the microscope when he viewed a few drops of pond water. -
Living cell discovery
Leeuwenhoek discovered bacteria from his observations of saliva. -
Suggested all organisms are composed of cells
French microscopist Henri Dutrochet suggested that all organisms are composed of cells. -
Nucleus discovered
Robert Brown, an English botanist, discovered/identified the nucleus in plant cells. He had published a book. -
Basic building blocks
Matthias Jakob Schleiden, a German botanist, proposes that all plant tissues are composed of cells, and that cells are the basic building blocks of all plants. This statement was the first generalized statement about cells. Still believed in the spontaneous theory. -
Cell theory
Theodor Schwann, a German botanist reached the conclusion that not only plants, but animal tissue as well is composed of cells. This ended debates that plants and animals were fundamentally different in structure. He also pulled together and organized previous statement on cells into one theory, which states: 1 - Cells are organisms and all organisms consist of one or more cells 2 - The cell is the basic unit of structure for all organisms -
Where does life come from
Albrecht von Roelliker discoveres that sperm and eggs are also cells. -
Basic unit of life
Carl Heinrich Braun reworks the cell theory, calling cells the basic unit of life. -
3rd part to the cell theory added
Rudolf Virchow, a German physiologist/physician/pathologist added the 3rd part to the cell theory. The original is Greek, and states Omnis cellula e cellula. This translates as all cells develop only from existing cells. Virchow was also the first to propose that diseased cells come from healthy cells. Evidence: He discovered yeast budding (formation of more yeast particles). -
Dispelled spontaneous theory
Louis Pasteur finally dispelled the theory of spontaneous generation by designing a swan-necked flask, which trapped microbes carried on dust particles that lodged in the neck of the flask. Air entered the flask but no microbes grew in the boiled broth because they had been trapped in the neck. -
First oil immersion
Carl Zeiss and Ernst Abbe produced the fi rst oil immersion objectives. Images could be magnifi ed over 1000×. -
Discovery of mitosis
Flemming, in 1879 discovers and descibes mitosis, the process that forms new cells, identical to that which created them.Walter Flemming used pigments to stain cells and saw they could pre-divide. -
Discovers cromatin materal
In 1882, Walter Flemming discovers cromatin material, a mass of genetic material that is made up of DNA and proteins. These two condense to form chromosomes, some of the most crictical parts of life. -
First electron microscope invented
First electron microscope invented by Ernest Ruska and Max Knoll (built and designed). It was the first transmission electron microscope (TEM). -
First scanning electron microscope invented
Ernest Ruska builds first scanning electron microscope (SEM) which transmits beam of electrons across surface of spectrum. -
Confocal microscope invented
Marvin Minsky invented confocal microscope. It allowed to look in layers. -
First practical laser scanning microscope developed
Thomas and Christoph Cremer devevlop first practical laser scanning microscope using focused laser beam. -
Scanning tunneling microscope (STM) invented
Gerd Binnig and Heinrich Rohrer invented the first scanning tunneling microscope (STM). It measures interactions between atoms rather than using light or electrons. -
Period: to
New optical microscope technology
Stefan Hall pioneers new optical microscope technology allowing to capture images with higher resolution -
Atoms of virus seen
Researchers of ULCA use cryoelectron microscope