Cell Theory Timeline
Read the text, and then fill in your notes! 
 The discovery of the cell was made possible through the
invention of the microscope.
 In 100 BC, Romans were able to make
glass, discovering that objects appeared to be
larger under the glass.
 In Italy during the 1100 AD, Salvino D’Armate made a piece of glass to fit over
one eye, allowing for a magnification effect to that eye.
 It was not until 1595 when a Dutch spectacle
maker Zacharias
Janssen began to experiment with
lenses that progress was made to microscopes. Janssen was
able to make a microscope with a 9x magnification (which
means it made the object look 9
times larger than it is in real life).
This was a large improvement,
but objects still looked blurry
with this scope. In 1595, Jansen and his father
built the first compound microscope. A
compound microscope has more than one lens so
that you can see more detail. The microscopes
we use today are compound.
 In 1665, Robert
Hooke
built a compound microscope that
was six inches long. It had two
convex-shaped lenses (think of an
upside down bowl shape) inside of
it. He used this scope to observe
specimens for his book Micrographia. Hooke also used a simpler microscope
with a single lens for examining specimens with direct transmitted light, because
this allowed for a clearer image. Hooke is most famous for first seeing cells in
dead cork. He came up with the term “cells” because he thought they resembled
rooms that monks lived in at the time. In Latin small rooms are called “cella”.
 In 1674 the microscope was improved by Anton
van Leeuwenhoek. He was a Dutchman who took an
interest in microscopes.
He was able to use a
simple microscope with
only one lens that allowed
for a magnification of
270x, whereas before objects could only be magnified 50 times. Leeuwenhoek
was also the first person to identify microorganisms in water. He called the
organisms “animalcules”. People thought he was nuts! Today, he is known as
the Father of Microbiology, which is the study of microscopic organisms. The
microorganisms he saw were protists and bacteria. Bacteria are found living
everywhere, and protists are tiny creatures that live in the water that you cannot
see with the naked eye (like amoebas! Cool!).
 These discoveries led to the development of the Cell Theory, which has 3
parts to it. Credit for developing 2 parts of the cell theory is given to two German
scientists:
Theodor Schwann and
Matthias Schleiden.
 In 1838, Schleiden suggested that every structural part of a plant was
made up of cells or the result of cells. In 1839, Schwann stated that along
with plants, animals are composed (made of) of cells or the product of cells in
their structures. This was a major advancement in the field of biology since
little was known about animal structure up to this point compared to plants.
From these conclusions about plants and animals, 2 of the 3 parts of cell
theory were developed:
1. All living things are made of cells.
2. Cells are the basic unit of life (smallest living thing).

Rudolph Virchow was a German doctor known for bringing more science
into medicine. He built on Theodore Schwann’s work with studying cells by
helping to disprove the Theory of Spontaneous Generation, which stated that
living things came from nonliving things. In 1855, Virchow added the third
part to cell theory:
3. Living cells come only from other living cells.