gather information from secondary sources to produce a time-line indicating improvements in microscopy that would have assisted Englemann in his work with Spirogyra
The web sites below are a starting point.
History of the Light Microscope About.com, Inventors
Microscopy Microscopy-UK and Onview.net Ltd, UK
Sample timeline | |
---|---|
Year | Improvement |
1886 |
Zeiss made a series of lenses that allowed structures to be resolved at the theoretical limits of visible light, which would have improved the detail (resolution) of what Englemann saw |
1924 |
Lacassagne developed the first autoradiographic method to see where radioactive polonium accumulated in biological specimens. If this technique had been available to Englemann, he could have used radioactively labelled water and autoradiographic techniques to visualise the production of oxygen in the violet and red wavelengths under the microscope. |
1930 |
Lebedeff designed and built the first interference microscope |
1931 |
Ruska built the first transmission electron microscope. The development of electron microscopes, scanning and transmission electron microscopes occurred in the 1940s and continued through the rest of the century, concentrating mainly on methods of fixing, staining and computer enhancement of images. These developments would not have helped Englemann. He required the plants to be actively photosynthesising and so fixing, staining or freeze fracture techniques developed recently would not have assisted him. |
1934 |
Zernike invented the phase contrast microscope. These developments allowed unstained living cells to be seen in detail for the first time. It was important for Englemann to view unstained living cells and he would have been able to watch the bacteria migrating to the oxygen rich areas. (After 1981 he would have been able to video tape it!) |
1952 |
Nomarski patented the system of differential interference contrast for light microscopes. This development would have assisted Englemann in a similar way to a phase contrast microscope. |