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Hans and Zacharais Janssen
in 1595 Hans and Zacharais Janssen (2 Dutch lens makers) developed a two lens microscope. This was the first compound microscope. it had a magnifying power of 20x -
Robert Hooke
Robert Hooke (an English scientist) used a hand made microscope using three lenses. He studied a cork because he was unsure how it floated yet was still firm and compressible. He coined the term "cells" for when he saw the different compartments, it reminded him of cells in a monastery. -
Francesco Redi
Franceso Redi (an italian physician and poet) was the first to suggest that spontaneous generationwasnt true. He said that maggots did not form on rotting meat but it was flies that layed eggs and then the eggs turned into maggots and then flies. He put rotting meat in a jar and then covered it. When maggots didnt generate he had proof but the scientific community discounted his work. -
Antoni van Leeuwenhoek
Antoni van Leeuwenhoek (a dutch businessman) was the first to see movement of different types of single cells that we now know as bacteria. He used a single lens microscope, much like a magnifying glass, and called the cells he saw "Animalcules" for their reasemblance to different animals. his microscope had a magnification of up to 250x. -
Lazzaro Spallanzani
Lazzaro Spallanzani (An Italian priest) refuted Needham's claims that a life force was needed to have spontaneous generation. He said that there were micro organisms in the air that landed and spawned new cells. He re-did Needham's experiments without air in the mix and no micro organisms grew. Other scientists didn't believe him and they said that the only thing he proved was that air was need for generation to occur. -
John Needham
John Needham (an English clergyman) set out to disprove the spontaneous generation theory. Everyone accepted that boiling something kills all the bacteria in the substance. John boiled chicken broth and covered it. in his experiment microorganisms still formed. He said that there needed to be some sort of life force for spontaneous generation to occur. -
Robert Brown
Robert Brown (A scottish Microscopist) was the first to identify the nucleus of the cell. Others had seen these before but he was the first to identify that it was vital for the cell. -
Louis Pasteur
In 1859, the French Academy of Sciences announced a contest for the best experiment to prove or disprove spontaneous generation. Louis Pasteur (a French chemist) submitted an experiment that used Needham and Spallanzani's basic work. He used an S-shaped flask and put broth into it. Air could get in and reach the broth but no organisms grew. This proved that spontaneous generation didnt occur and that there are micro organisms in the air. -
High Resolution Electron Microscope: Continued
- Scanning EM: Developed in the 1940's, this has the specimen encased in a electron dense metal (ex. Gold) and then electrons are bounced off it and then collected and made into an image. This is good for a magnification for up to 300,000x.
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High Resolution Electron Microscope
In 1938 James Hillier (a Canadian scientist) and Albert Prebus developed the first high resolution electron microscope. An electron microscope uses one of two ways to see an image.
1. Transmission Electron Microscope: This depends on a beam of electrons passing through a very thin section of fixed and stained tissue. The electrons that pass through will land on a screen producing an image. This is good for a magnification up to 1,500,000x. -
Confocal Microscope
The original patent was put in place in 1957 but this technology wasnt really developed until the 1980's. In this microscope, a laser concentrates light onto a specimen. The light is then reflected back through a pinhole onto a electronic detector that translates the light into an image.
