Using the concept that synthetic dyes could combine with some parts of a cell, but not others, Ehrlich theorized that a dye could be made to kill only the target pathogen cells and not human cells. He found a dye called "Trypan red" which targeted trypanosomes, a type of protozoa that caused sleeping sickness.
A visual chronology of Asimov's ~1500 scientific inventions and discoveries.
