microscopy

• what happened in the cell theory in 1665?

  cell first observed. Robert Hooke, an english scientist observed the structure of thinly sliced cork using an early light microscope. He described the compartments as cells, as this was dead plant tissue he was observing only cell walls
• 1674-1683

  first LIVING cells observed, Anton van Leeuwenhoek, a dutch biologist, developed a technique for creating a powerful glass lenses and used these to examine samples of pond water. The first person to observe bacteria and protoctista as well as red blood cells, sperm cells and muscle fibres
• 1832

  evidence for the origin of new plant cells. Barthélemy Dumortier, a belgian botanist, was the first to observe cell division in plants, providing evidence for the theories of the time (evolution)
• 1833

  nucleus first observed. Robert Brown, an english botonist describes the nucleus of a plant cell
• Matthias Schleiden, a german botanist, proposed that all plant tissues are composed of cells.
• Jan Purkyně, a Czech scientist, was the first to use a microtome to make ultra thin slices of tissue for microscopic examination.
• Based on his observations, Jan Purkyně proposed that not only are animals composed of cells but also that the basic cellular tissue is clearly analogous to that of plants.
• Theodor Schwann, a german physiologist, independently made a similar observation and declared that all living things are composed of cells and cell products.
• Theodor Schwann is the scientist who is credited with the birth of the cell theory.
• 1844 (1855)

  evidence for the origin of new animal cells

  Robert Remark, a polish/german biologist, was the first to observer cell division in animal cells, disproving the existing theory that new cells originate from within old cells. He was not belived at the time, and Rulofl Virchow, a german biologist, published these findings as his own a decade later in 1855.
• 1860.

  spontaneous generation disproved. Louis Pasteur disproved the theory of spontaneous generation of cells by demonstrating that bacteria would only grow in a sterile nutrient broth after it had been exposed to air.
• how does a compound light microscope work?

  consists of 2 lenses; the objective lens, which is placed near the specimen and an eyepiece lens, which the specimen is viewed through. The objective lens produces a magnified image, which is magnified again by the eye piece lens.