Seeing Cells in Life

The 17th century brought microscopes, which made looking at small living material possible. Observers recorded and shared observations through letters and publications, with illustrations to show others what they saw.

In his 1665 Micrographia, British microscopist Robert Hooke applied the term “cell” to the empty spaces he observed in slices of cork, vegetables, and sea shells. His cells were units of organization rather than living things.

A seventeenth century microscope used by Robert Hooke HoverTouch to magnify
Hooke's Microscope
Microscope view of cells in cork - porous white shape over black background HoverTouch to magnify
Cells observed in cork

Meanwhile, in the Netherlands, Anton van Leeuwenhoek focused on living materials. He saw wiggling ovals in scrapings from his mouth and called them “animalcules.” Non-moving disks in blood he called “corpuscles.”

Illustrations of animal cells HoverTouch to magnify
Dental plaque animalcules
MBL Rare Books Collection
Blood cells as illustrated by Anton van Leeuwenhoek in 1700 HoverTouch to magnify
Blood corpuscules
Painting of a man sitting at a desk , hand on his cheek, while writing. Another person stands behind him looking over his shoulder. HoverTouch to magnify
van Leeuwenhoek
Sketch of Anton van Leeuwenhoek's single lens microscope HoverTouch to magnify
Leeuwenhoek's microscope
Others also began to see organized units of life that they called cells. They focused on observing and describing what they saw and did not yet develop a theory of cells. That came in the 19th century with improved microscopes. What was that cell theory?