Plant cells possess

Plant cells possess cell wall, plastids and large central vacuole. Schwan (1839), a British Zoologist, studies different types of animal cells and reported that cells had a thin outer layer. Which is today known as the ‘plasma membrane’. Based on his studies on plant tissues, he also concluded that the presence of a cell wall is a unique character of the plant cells. On the basis of this, Schwann proposed the hypothesis that the bodies of animals and plants are composed of cells and its products Scheiden and Schwann together formulated the cell theory. This theory however, did not explain as to how new cells were formed. Rudolf Virchow (1855) first explained that cells gets divided and new cells are formed from pre-existing cells (Omnis cellula-e-cellula) He modified the hypothesis and Schwann to give the cell theory a final shape. Cell theory as understood today is (i) All living organism are composed of cells and products of cells (ii) All cells arise from pre-existing cells