The Cell Theory

 

In 1838 Schlieden and Schwann first proposed the cell theory.  They stated that:

1.  All living things are made of cells
2.  The cell is the basic unit of all living organisms.

In 1855 Virchow added another rule.  It was:

3.  All cells come from preexisting cells.


Who were the other players in this?

Robert Hooke.  He first coined the term cell in 1665 while sketching a slice of cork under his newly built compound microscope.


Redi - His observations linking flies with maggots in rotting meat led to the beginning of the end for spontaneous generation.  His work was later verified by Pasteur who made similar observations with yeast turning grape juice into wine, and then bacteria spoiling the wine.


Leeuwenhoek - observed living single-celled in pond water under his microscopes.  He also observed that blood of a variety of organisms had cells in them.

Robert Brown - his observations showed that there was potential complexity within the cells by observing and naming the cell nucleus.  While it may have been observed earlier, Brown was one of the first to publish these into scientific literature. 



What evidence supports cell theory?

Observation with the microscope.  As time went on and better light microscopes were developed, the key characteristics of all living things certainly followed the first 2 rules.  All living things had cells in them and the smallest living thing is made up of cells.

With the discovery of dyes that stained the nucleus and other cell parts, rule 3 was verified by Walther Fleming in 1879.