The cell theory is one of the fundamental concepts in biology. It states that all living things are made up of cells, and that cells are the basic unit of life.

But how was this theory formulated? Let’s take a look at the history.

Discovery of Cells

In the 17th century, Antonie van Leeuwenhoek, a Dutch scientist, was the first to observe living cells under a microscope. However, it wasn’t until the 19th century that more advancements were made in studying cells.

Robert Hooke

In 1665, Robert Hooke, an English scientist, studied cork under a microscope and noticed small compartments that he called “cells”. This was the first time the term “cell” was used to describe biological structures.

Theodor Schwann

In 1839, Theodor Schwann, a German physiologist and zoologist, observed animal cells under a microscope and concluded that all animals are made up of cells.

Matthias Schleiden

Around the same time as Schwann’s discovery, Matthias Schleiden, a German botanist, observed plant cells under a microscope and concluded that all plants are made up of cells.

Formulation of Cell Theory

Based on their individual observations and research, Schwann and Schleiden came together to formulate the cell theory. In 1839 they jointly published their findings: “All living things are composed of one or more cells.”

However, it wasn’t until almost two decades later in 1855 that Rudolf Virchow added to this theory by stating that all new cells arise from pre-existing cells. This completed what we now know as the cell theory:


The formulation of the cell theory was a significant milestone in biology. It allowed scientists to understand the fundamental building blocks of life, and laid the foundation for further research in fields such as genetics, microbiology, and immunology. Today, we continue to expand our knowledge of cells and their functions, but the cell theory remains a crucial concept that guides much of our understanding of living organisms.