Now, while Paul Ehrlich’s head was an encyclopedia of chemical knowledge, his hands were not the hands of an expert chemist. He hated complicated apparatus as much as he loved complicated theories. He didn’t know how to manage apparatus. He was only a chemical dabbler making endless fussy little starts with test-tubes, dumping in first this and then that to change the color of a dye, rushing out of his room to show the first person he met the result, waving the test-tube at him, shouting: “You understand? This is splen-did!” But as for delicate syntheses, those subtle buildings-up and changings of dyes, that was work for the master chemists. “But we must change this dye a little--then it will work!” he cried. Now Paul Ehrlich was a gay man and a most charming one, and presently back from the dye factory near by came that benzopurpurin color, with the sulfo-groups properly stuck onto it, “changed a little.” Under the skin of two white mice Shiga shot the evil trypanosomes of the mal de Caderas. A day passes. Two days go by. The eyes of those mice begin to stick shut with the mucilage of doom, their hair stands up straight with their dread of destruction--one day more and it will be all over with both of those mice.... But wait! Under the skin of one of those two mice Shiga sends a shot of that red dye--changed a little. Ehrlich watches, paces, mutters, gesticulates, shoots his cuffs. In a few minutes the ears of that mouse turn red, the whites of his nearly shut eyes turn pinker than the pink of his albino pupils. That day is a day of fate for Paul Ehrlich, it is the day the god of chance is good, for, like snows before the sun of April, so those fell trypanosomes melt out of the blood of that mouse! Away they go, shot down by the magic bullet, till the last one has perished. And the mouse? His eyes open. He snouts in the shavings in the bottom of his cage and sniffs at the pitiful little body of his dead companion, the untreated one. He is the first one of all mice to fail to die from the attack of the trypanosome. Paul Ehrlich, by the grace of persistence, chance, God, and a dye called “Trypan Red” (its real chemical name would stretch across this page!) has saved him! How that encouraged this already too courageous man! “I have a dye to cure a mouse--I shall find one to save a million men,” so dreamed that confident German Jew.