μῖτος

The Greek word mitos (μῖτος) means 'thread'—and under the light microscope in the 1870s, cellular biologists noticed something extraordinary: during cell division, the nucleus erupted into what looked like tangled threads. These threads were chromosomes condensing into visible shapes. They looked like thread. So Walther Flemming, a German anatomist, called the process mitosis.

Flemming spent years staring through microscopes at the threads. In 1882, he published 'Zellsubstanz, Kern und Zelltheilung'—a meticulous account of how the threads aligned, separated, and moved to opposite poles of the cell. His observations were so precise that we still use his named stages: prophase, metaphase, anaphase, telophase.

But the threads aren't doing the moving. The nucleus is being pulled apart by microtubules—tiny fibers made of protein. We now know the mechanism, and it has nothing to do with threads pulling themselves. Yet we still call it mitosis because Flemming's name stuck. The word is a century old, and we've kept it even though what we call threads are invisible until we stain them.

Mitosis is now the most important biological process most people have never heard of—it's how you grow, how you heal, how your gut replaces itself every few days. The word that means 'thread' is the name for the process that keeps you alive. Flemming named it for what he could see, not for what was actually happening.