The Song of the Cell: An Exploration of Medicine and the New Human

by Siddhartha Mukherjee

animalcules,” he called them. Telescopists had seen macroscopic worlds—the blue-tinged moon, gaseous Venus, ringed Saturn, red-flecked Mars—but no one had reported a marvelous cosmos of a living world in a raindrop. “This was to me among all the marvels that I have discovered in nature the most marvelous among them all,” he wrote in 1676. “No greater pleasure has yet come to my eye than these spectacle of the thousands of living creatures in a drop of water.”II He wanted to look more, to build finer instruments to visualize this captivating new universe of living beings. And so Leeuwenhoek purchased the highest-quality beads and globules of Venetian glass and then ground and polished them laboriously into perfectly lenticular shapes (some of his lenses, we now know, were made by stretching a rod of glass into a thin needle on a live flame, breaking the end, and then letting the needle “bubble” into a lens-shaped globule). He mounted these lenses on thin metal plates, crafted of brass, silver, or gold, each with an increasingly complex system of miniature armatures and screws to move parts of the instrument up and down and attain perfect focus. He made nearly five hundred such scopes, each a marvel of meticulous tinkering. Were such creatures present in other samples of water