from an ancient Chalk Graveyard
IN 1668, ANTONI VAN Leeuwenhoek stood on the coast of England, fascinated by a white chalk cliff. How could this young man from Holland have known that, centuries later, he would be remembered as one of the most celebrated scientists of all time? He could not have realized that a homemade magnifying lens tucked in his luggage was the most power ful microscope on Earth at the time. He was simply following his curiosity.
Antoni picked up a crumble of chalk from beside the cliff and set it on the pin of his metal microscope, holding it against his face and up to the Sun. As he carefully rotated a tiny focus screw, “very small transparent particles” appeared on the surface of the chalk, “lying one upon another.” The instant that light came through the glass lens and energized the photoreceptors in his eye was one of the greatest moments in the history of science. He was not looking at living organisms. Rather, he was looking at particles from organisms that lived in the past, a trace of an entire microscopic world that he would soon discover. It was Antoni’s first glimpse of life beyond the edge of sight. No Egyptian pha raoh, no Greek philosopher, not Leonardo da Vinci, not Sir Isaac Newton, not Galileo Galilei, no one had ever seen a biological entity of this size.
If we look at chalk today from the White Cliffs of Dover in England, we can locate the same transparent particles. We can also use modern microscopes to zoom in closer and see much more. Antoni’s simple light microscopes created images that to his eyes were 70 to 300 times larger than the actual size of the objects. It was technology that bordered on magic in the seventeenth century.
A scanning electron microscope can magnify an object well over 100,000 times. By directing a beam of electrons against the chalk and analyzing how the electrons bounce off the surface to create an image, we see a mysterious landscape of discshaped objects. What are these structures? The discs are themselves