2.1The Discovery of Cells
In 1665, Robert Hooke, an English physicist, published a book titled Micrographia. Using a homemade microscope, Hooke carefully observed minute structures invisible to the naked eye, such as needle tips and organisms such as fleas, and recorded these in the book. A famous drawing from this book is shown in Figure 2-1. The sketch shows a cork composed of many small compartments surrounded by walls. Hooke named these small compartments "cells," meaning "small rooms." At that time, however, Hooke only described the cell walls as partitions of dead plant cells and did not realize that the contents within these compartments were the building blocks of life.
Two hundred years later, however, based on various observations, two Germans named Matthias Jakob Schleiden and Theodor Schwann claimed that these "cells" were fundamental and functional units common to all life. This idea has become widely accepted and is now one of the most important concepts in biology.