cell the unit of Life. (1)

The cell- 

Cell is the fundamental structural and functional unit of all living organism.

Antonie van leeuwenhoek first saw and describe a live cell .

Robert brown later discovered the nucleus.

The invention of the microscope and its improvement leading to the electron microscope revealed all the structural details of the cell.

Cell theory-

Mattias schleiden, German botanist, examine a large number of plants and observed that all plants are composed of different kind are cells .

Theodore Schwann 1839 , British zoologist, 

Studied different types of animal cell and reported that sil had a thin outer layer known as the plasma membrane.

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

On the basis of Schwann proposed the hypothesis of animal and plants are composed of cell and their product.

Rudolf virchow (1855) first explained that cell divided and cells are formed from pre existing cell (omnis cellula e cellula).

He modified the hypothesis of schleiden and Schwann to give the cell theory a final shape.

Cell theory as-

(1) all living organism are composed of cells and product of cell.

(1) all cells arise from preexisting cell.