“Nothing can get into that drop--only the rods are there--now we’ll see if they will grow,” whispered Koch as he slid his hanging-drop under the lens of his microscope; in a kind of stolid excitement he pulled up his chair and sat down to watch what would happen. In the gray circle of the field of his lens he could see only a few shreddy lumps of mouse spleen--they looked microscopically enormous--and here and there a very tiny rod floated among these shreds. He looked--fifty minutes out of each hour for two hours he looked, and nothing happened. But then a weird business began among the shreds of diseased spleen, an unearthly moving picture, a drama that made shivers shoot up and down his back. The little drifting rods had begun to grow! Here were two where one had been before. There was one slowly stretching itself out into a tangled endless thread, pushing its snaky way across the whole diameter of the field of the lens--in a couple of hours the dead small chunks of spleen were completely hidden by the myriads of rods, the masses of thread that were like a hopelessly tangled ball of colorless yarn, living yarn--silent murderous yarn. “Now I know that these rods are alive,” breathed Koch. “Now I see the way they grow into millions in my poor little mice--in the sheep, in the cows even. One of these rods, these bacilli--he is a billion times smaller than an ox--just one of them maybe gets into an ox, and he doesn’t bear any grudge against the ox, he doesn’t hate him, but he grows, this bacillus, into millions, everywhere through the big animal, swarming in his lungs and brain, choking his blood-vessels--it is terrible.” Time, his office and its dull duties, his waiting and complaining patients--all of these things became nonsense, seemed of no account, were unreal to Koch whose head was now full of nothing but dreadful pictures of the tangled skeins of the anthrax threads. Then each day of a nervous experiment that lasted eight days Koch repeated his miracle of making a million bacilli grow where only a few were before. He planted a wee bit of his rod-swarming hanging-drop into a fresh, pure drop of the watery fluid of an ox-eye and in every one of these new drops the few rods grew into myriads. “I have grown these bacilli for eight generations away from any animal, I have grown them pure, apart from any other microbe--there is no part of the dead mouse’s spleen, no diseased tissue left in this eighth hanging-drop--only the children of the bacilli that killed the mouse are in it.... Will these bacilli still grow in a mouse, or in a sheep, if I inject them--are these threads really the cause of anthrax?”