The Development of the Cell Theory
Virchow’s Cell Theory States:
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All living organisms are made of one or more cells.
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Cells are the basic units of structure and function in all organisms.
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All cells come from previously existing cells.
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The activity of an entire organism depends on the total activity of its independent cells.
Ancient Times
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Ancient peoples were always on the look-out for ways that organisms can be used by them.
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They passed on their understanding orally.
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Some civilizations supported “great thinkers” – and philosophers, but they rarely based their
thoughts on observation or experiments.
334 B.C.E - Aristotle
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Greek philosopher, Aristotle, began to observe nature.
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He classified all known organisms as either a Plant or and Animal.
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He wrote that living things can arise spontaneously from non-living matter.
1268 – 1st Eyeglasses
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Roger Bacon, an English friar made reference to a pair of eye glasses.
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This meant that glass was being developed and used in a way that makes it easier to see small
things.
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Physics
1590 – 1st Microscope
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Zacharias Janssen, a Dutch eyeglass maker, made the first microscope by placing two lenses
on top of one another to make extra-large images.
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Physics
1600’s
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People started to suggest that life can only come from other forms of life rather than through
spontaneous generation (as was suggested by Aristotle).
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William Harvey said that maggots do not come from the meat itself but from tiny eggs too
small to be scene.
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Biology/Medicine
1665 – 1st Cells Seen
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Robert Hooke (1635-1703) published a book with illustrations of tree bark as seen through a
simple compound (2 lens) microscope.
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Physics
1668 – 1st Experiments about origins of maggots
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Francesco Redi (1626-1697) conducted experiments to prove that maggots do not appear in
meat if flies cannot land on it!
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Biology
1674 – 1st Microscopic Organisms Seen!
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Anton van Leeuwenhoek (1632-1723) reported being able to see tiny beasties (0.002 mm)
using a simple single-lens microscope.
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Biology
1753 – Birth of Classification
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Carolus Linnaeus (1707-1778) began to show people the great diversity of living things by
exploring methods of classifying them into 5 main Kingdoms.
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Biology
1770 – Advancement of Microscopes
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Microscopes became sturdier and easier to use.
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Flaws in glass production still caused images to be blurry and have coloured halos.
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Physics
1809 – 1st Science Texts for Students
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Jane Haldimand (1769-1858) wrote textbooks for young people to learn about science.
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Words such as “cell”, “cellular system” and “Cellular tissue” appear in the book.
1820’s – Better Glass = Better Lens
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Microscope quality improved with the production of better glass.
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Many English companies competed to produce the best microscope.
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Physics
1825 – Book “Cells from Cells”
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Francois Vincent Raspail (1794-1878) wrote a book called “Every cell is derived from a preexisting cell”.
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Biology
1830 – Cells are studied
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Biology was becoming an important science and the body of knowledge was growing,
especially since the improvement of microscopes.
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Scientists began to study the cell extensively.
1831 – Nucleus of Cell Found
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Robert Brown (1773-1858) was the first to think of the nucleus as a regular part of a living cell.
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The nucleus was still hard to see though without the invention of the electric light for his
microscope.
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Biology
1838 – Plant cells!
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Matthias Jacob Schleiden (1804-1881) made the claim “All plants are made of cells”.
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Cells are alive!
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Biology
1839 – Animal cells!
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Theodor Schwann (1810-1882) made the claim “All animals are made of cells”.
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Cells are the basic structure of life!
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Biology
1845 – Cell Basic Unit of Life
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Alexander Carl Heinrich Braun (1805-1877) said:
“The cell is the basic unit of life”.
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Cells are made of protoplasm enveloped by a flexible membrane.
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Biology
1856 – Staining technique developed
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18 year old, William Henry Perkin (1838-1907) developed a new purple dye for staining cell
parts making it easier to see cell parts with a microscope.
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Chemistry
1858 – Article on Evolution
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Charles Darwin (1809-1882) & Alfred Wallace (1823-1913) read their article on “Tendency of
species to form variations”.
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Biology
1858 – Cell Theory Outlined
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Rudolph Virchow (1821-1902) developed his Cell Theory that is still largely accepted today.
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Biology
1860’s – The end of the “Spontaneous Generation” debate
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Louis Pasteur (1822-1895) conducted a series of experiments that once and for all put to rest
the idea of spontaneous generation and concluding that living organisms do not arise from
non-living matter.
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Biology
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