Question

Briefly give the contributions of the following scientists in formulating the cell theory
a. Robert Virchow
b. Schielden and Schwann

Answer 1

Rudolf Virchow

The following are the contributions of Rudolf Virchow :

• In 1885, he explained that cells divide and new cells are formed from the pre-existing cells (Omnis cellula-e cellula).
• He modified the hypothesis given by Schleiden and Schwann as follows:
  • All living organisms are composed of cells and products of cells.
  • All cells arise from pre-existing cells

Scleiden

In 1838, Matthias Schleiden, a German botanist, after examination of a variety of plants, stated that all plants are composed of different types of cells. These cells then form the tissues of the plant.



Schwann

In 1839, Theodore Schwann, a British Zoologist, after studying a variety of animal cells, reported the presence of a thin outer layer around the cells, which is now termed the ‘plasma membrane’. He also concluded that the presence of the cell wall is a unique feature of the plant cells.