-
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.
-
Dutch technicians developed the art of grinding glass lenses and the first compound (two lens) microscope was made by Hans and Zacharias Janssen.
-
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.
-
Anton van Leeuwenhoek, a Dutch biologist, looks at pond water with a microscope he made lenses for.
-
A Dutch lens grinder and microscope maker, Anton van Leeuwenhoek, saw microorganisms under the microscope when he viewed a few drops of pond water.
-
Leeuwenhoek discovered bacteria from his observations of saliva.
-
French microscopist Henri Dutrochet suggested that all organisms are composed of cells.
-
Robert Brown, an English botanist, discovered/identified the nucleus in plant cells. He had published a book.
-
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.
-
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
-
Albrecht von Roelliker discoveres that sperm and eggs are also cells.
-
Carl Heinrich Braun reworks the cell theory, calling cells the basic unit of life.
-
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).
-
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.
-
Carl Zeiss and Ernst Abbe produced the fi rst oil immersion objectives. Images could be magnifi ed over 1000×.
-
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.
-
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 by Ernest Ruska and Max Knoll (built and designed). It was the first transmission electron microscope (TEM).
-
Ernest Ruska builds first scanning electron microscope (SEM) which transmits beam of electrons across surface of spectrum.
-
Marvin Minsky invented confocal microscope. It allowed to look in layers.
-
Thomas and Christoph Cremer devevlop first practical laser scanning microscope using focused laser beam.
-
Gerd Binnig and Heinrich Rohrer invented the first scanning tunneling microscope (STM). It measures interactions between atoms rather than using light or electrons.
-
Stefan Hall pioneers new optical microscope technology allowing to capture images with higher resolution
-
Researchers of ULCA use cryoelectron microscope