What did virchow observe that led him to determine one of the main components of cel theory?

In the year 1850, Rudolf Virchow was studying cells under a microscope, when he observed that cells were dividing and forming new cells. Realizing what he had observed, he understood that living cells reproduce new cells through division. Basing on his conclusion and realization, Virchow proposed that living cells came only from the other living cells.

The hawk receives 0.1% energy from the caterpillar although the caterpillar gets eaten by another bird smaller than the hawk first