How this phrase fits into the history of cell theory?

The phrase “Omnis cellula e cellula” is central to the evolution of cell theory. Initially, Matthias Schleiden and Theodor Schwann (1838–1839) proposed that all living organisms are composed of cells and that the cell is the fundamental unit of life. However, they didn’t clearly explain how new cells are formed. Many still believed in spontaneous generation, the idea that life could arise from non-living matter.

In 1855, Rudolf Virchow expanded the cell theory by stating “Omnis cellula e cellula,” meaning new cells arise only from pre-existing cells. This transformed the cell theory into a complete biological principle, explaining both the structure and reproduction of cells.

Virchow’s addition eliminated the concept of spontaneous generation and established that all biological processes — from growth and development to reproduction — occur through cell division. This marked a turning point in biological science, paving the way for discoveries like mitosis, meiosis, and modern genetics.

In short, Virchow’s phrase completed the modern cell theory, which now states: 

•  all living things are made of cells, 
• cells are the basic units of life, and
• all cells arise from existing cells.