Chapter 3: Cells And Tissues

In the late 1600s, Robert Hooke was looking through a microscope at some plant tissue - cork. He saw some cubelike structures that reminded him of the long rows of monk's rooms (or cells) at the monastery, so he named these structures cells. The living cells that had formed the cork were long since dead. However, the name stuck and is still used to describe the unit, or building block, of all living things, plants and animals alike. The human body has trillions of these microscopic building blocks.