Briefly give the contributions of the following scientists in formulating the cell theory

a. Robert Virchow

b. Scheilden and Schwann

a. Rudolf Virchow first explained that the cells divide and new cells are formed from the pre-existing cells. He gave the modern cell theory by modifying the old one given by Schleiden and Schwann –

• all living organisms are composed of cells and products of cells.

• all cells arise from pre-existing cells.

b. • In 1838, Schleiden conducted tests on different plants and concluded that all the plant are made up of different types of cells which together form plant tissues.

• In 1839, Schwann studied different types of animal cells and reported that cells had a thin outer layer which is today known as the ‘plasma membrane’.

• He also concluded, based on his studies on plant tissues, that the presence of cell wall is a unique character of the plant cells.

• So the cell theory with the contribution of the two stated that the bodies of animals and plants are composed of cells and products of cells.