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Invention of the microscope by the Janssen brothers
It is believed that the microscope was invented around 1595, by Dutch lensmakers Hans and Zacharias Janssen. They created it using a two-lens system of an eyepiece, ocular lens and an objective lens. This was the very first "compound" microscope. which meant that it used more than one lens to magnify an object. -
Hooke's microscope
In 1665, Robert Hooke was using a microscope that he made by hand which had a three lens system. It had a beam of light focused on the specimen by passing the light through a glass flask filled with water. With his handmade microscope, Hooke was able to view plants, animals, and non-living objects. While Hooke was examining a cork with his microscope, he was able to discover cells. -
Van Leeuwenhoek's microscope
Around 1665, Dutch businessman, Antoni Van Leeuwenhoek, used only a single-lens microscope, like a magnifying glass. He was the first to view the movement of different types of single cells, which is now known as bacteria, sperm, and unicellular protozoa. These were the first observations that were made of individual free-living cells surviving as independent systems. The qaulity of his lenses was the main reason for his success. -
Redi and his theory of spontaneous generation
In 1668, Francesco Redi questioned the belief that maggots formed from raw meat spontaneously. He believed that flies laid their eggs in the meat. He set up an experiment by setting out flasks that contained raw meat, some were sealed, covered in gauze, and some were open to the air. The maggots were only found in the flasks that were open and available to flies so they could lay their eggs. This started the idea of spontaneous generation, that life could emerge from non-living matter. -
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Development of the Achromatic lens
early compound microscopes were less effective than the single lens because the images were often blurry, with a halo of light around the object being observed. Throughout the 18th century, a combination of lenses known as achromatic lens was developed to control the halo and improve the amount of detail that could be seen. -
Needham's experiment and findings
In 1745, John Needham boiled chicken broth and put it in a flask and sealed it in order to prove that living things could be produced from non-living matter. Micro-organisms still appeared despite the idea everyone believed that boiling killed micro-organisms. He suggested that a life force produced spontaneous generation. -
Spallanzani's experiment and findings
Around the same time, Lazzaro Spallanzani disapproved Needham's claim and suggested that there were micro-organisms in the air that were responsible for the new growth. He repeated Needham's experiment but avoided the air in the flask. Nothing grew in the remaining broth. -
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The cell theory
It is stated in the cell theory that every living thing is either made up of one or more cells and the materials that are produced by these cells. Every life function takes place inside of cells, therefore, they are the smallest of all units of life. pre-existing cells produce all cells through cell division -
Robert Brown and the cell theory
The importance of the cell as the functional unit of life was finally recognized in 1830. Microscopist Robert Brown identified the nucleus, during his study of orchids. He was the first to recognize that this cell structure was related to the importance for cell function. -
MJ Schleiden and Theodor Schwann
In 1838, Schleiden made an observation that all plants were composed of cells and he stated that the nucleus was the structure that was responsible for the development of the rest of the cell. Schwann who was studying animal physiology believed that plant and animal tissue must have similarities. He found related structures between the plant tissue, animal tissue, and the nucleus. They proposed that plants and animals were composed of cells and that cells were the basic unit of all organisms. -
Rudolf Virchow and the cell theory
Rudolf Virchow extended the cell theory in 1859 with his statement that all cells only appear from pre-existing cells. -
Pasteur and the French Academy of Science contest
In 1859, The French Academy of Sciences held a contest for the best experiment to prove or disprove spontaneous generation. He used the work of Needham and Spallanzani, but instead, before boiling the meat broth in a flask, he heated the neck of the flask and bent it into the shape of an "S" so that only air could reach the broth. Nothing grew in the broth, providing evidence that spontaneous generation didn't occur. He also provided evidence that micro-organisms are found in the air -
Pateur's excerpt from Sorbonne Scientific Soirée
Pateur stated in his excerpt that the difference between the two flasks in his experiments. In the first flask, the germs could fall down the flask and reach the liquid where it could find the nourishment needed to develop. In the second flask, it was impossible for airborne dust to enter the flask. -
How I think the development of the microscope pushed the understanding and development of cell theory.
I believe the development of the microscope pushed the understanding and development of cell theory because scientists were able to view objects closer than ever before. Such as when scientist Robert Brown was able to discover the nucleas by viewing an orchid through a microscope.
