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A timeline showing the contribution to cell theory each of the following scientists made: - Hans and Zacharias Janssen - Robert Hooke - Anton Leeuwenhoek - Matthias Schleiden - Theodor Schwann - Rudolf Virchow - August Weismann. What is cell theory? = Cell theory refers to the idea that cells are the basic unit of structure in every living thing.

Created by sciencetimeline on Mar 14, 2011

Last updated: 03/15/11 at 04:32 AM

• August Weismann
  1880

  August Weismann introduced an important corollary to the biogenic law which was: "that cells living today can trace their ancestry back to ancient times" i.e. there must be a common ancestral cell. He also introduced his book 'the germ-plasm'. In which he explained his germ plasm theory. This theory states that multicellular organisms consist of germ cells that contain and transmit heritable information, and somatic cells which carry out ordinary bodily functions.
  http://kentsimmons.uwinnipeg.ca/cm1504/celltheory.htm http://en.wikipedia.org/wiki/Germ_plasm

• Rudolph Virchow - Cell reproduction
  1855

  Rudolph Virchow was a German Physician who studied cell reproduction. He said ◦“Where a cell exists, there must have been a preexisting cell…..” He also published a book called Cellular Pathology in which he he set out methods and objectives of pathology and demonstrated that cell theory applied to diseased tissue as well as healthy.
  http://scienceworld.wolfram.com/biography/Virchow.html

• Theodor Schwann - founder of the theory of the cellular structure of animal organisms
  1839

  Theodor Schwann was the founder of the theory of the cellular structure of animal organisms. Schwann proved that animal cells are in physiological and morphological accordance with those of plants, and that all animal tissues proceed partly from cells and are partly composed of them. He explained all this in his book.
  http://www.newadvent.org/cathen/13592b.htm

• Matthias Schleiden - All plants are made up of cells
  1838

  Schleiden was German Botanist the viewed plant parts under a microscope. He discovered that all plants are made up of cells. He is was also considered to be the co-founder of cell theory together with Schwann, with whom he consulted.
  http://www.quincy.k12.mi.us/science7/cells/cell_theory.htm

• Anton Van Leeuwenhoek
  1674

  Anton van Leeuwenhoek built a simple microscope with only one lens to examine blood, yeast, insects and many other tiny objects. Leeuwenhoek was the first person to describe bacteria, and he invented new methods for grinding and polishing microscope lenses that allowed for curvatures providing magnifications of up to 270 diameters, the best available lenses at that time.

• Robert Hooke - discovered the porous structure of cork which he termed "cells."
  1665

  He published Micrographia in 1665, which was the first treatise on microscopic principles and observations. Hooke made many discoveries in microanatomy, and discovered the porous structure of cork which he termed "cells." He viewed cells simply as a container, however, and not as the basic unit of life.
  http://scienceworld.wolfram.com/biography/Hooke.html

• Hans and Zacharias Janssen - First compound microscope
  1595

  Invented the first compound microscope. This microscope consisted of two tudes that slid within one another, and had a lens at each end.This was an advanced microscope that had 3 to 9 times power magnification. They experimented with multiple lenses placed in a tube. The Janssens observed that viewed objects in front of the tube appeared greatly enlarged, creating both the forerunner of the compound microscope and the telescope.
  http://www.enchantedlearning.com/inventors/1500.shtml