The Cell Concept

One of the most important concepts in biology is the basic unit of structure and function in living organisms is the cell. 

This is known as the cell theory  as was jointly proposed by two scientists, namely Schleiden, a Belgian botanist, in 1838 and Schwann a German zoologist, in 1839.

The discovery was due to the fact that during the nineteenth century there were dramatic improvements in the quality of lenses for use in microscopy and this, in turn, led to great interest in the structure of living organisms.

An essential part of the cell theory is the idea, first proposed in 1855, that new cells only come from pre-existing cells.