Briefly give the contributions of the following scientists in formulating the cell theory
(a) Rudolf Virchow
(b) Schleiden and Schwann

Explanation

(a) Rudolf Virchow (1855) first explained that the cells divide and new cells are formed from the pre-existing cells (omnis cellula e cellula).
Virchow was the first to demonstrate that the cell theory applies to diseased tissue as well as to healthy tissue. He also engaged his research in the fields of archeology and anthropology
(b) Schleiden and Schwann observed the cells and cell membranes for the first time. They proposed the cell theroy which explains that the animal and plant cells are composed of cells and product of cells.
Theodore Schwann (1839) studied different types of animal cells and reported that cells had a thin outer layer which is called as plasma membrane. Schleiden alos concluded on plant studies, i.e., the presence of cell wall is unique character of plant cells. Thus, they proposed that plants and animals are composed of cells and their products.