Who stated first of all that new cells are formed from a division of pre-existing cells?

Hint: One cell divides and forms two or more cells by cell division.
In the mitotic cell division, one parent cell divides to form two daughter cells that have the same number of chromosomes as that of parent cells.
In the meiosis, one parent cell divides to form four daughter cells that have a half the number of chromosomes to that of parent cells

Complete answer: In 1858, Rudolph Virchow observed the process of cell division and claimed that cells only arose from the division of pre-existing cells.
He stated in his cell theory that all living organisms are made up of single or multiple cells. His famous phrase was Omnis cellula e cellula – which means that all cells originate from a pre-existing cell.
Cells are the basic structural unit of all organisms and also the basic unit of the reproductive system.

Additional information: The three beliefs to the cell theory are as follows:
1. All the living organisms are made up of one or more cells – cells can be prokaryotic or eukaryotic.
2. The cell is the basic structural and organizational unit of any organism.
3. Every cell arises from a pre-existing cell.

Note: In biology, cell theory is one of the most controverting scientific theories. Now, it is a well-established fact that all living organisms are comprised of cells.
All the organisms have some basic structural or organizational unit of life – which is known as a cell. It is now proved and established by the scientists that all cells come from a pre-existing cell only.