Page:Microbe Hunters.djvu/159

Now Koch, in taut intent months, confirmed his first success—he went after proving it with a patience and a detail that made me sick of his everlasting thoroughness and prudence as I read the endlessly multiplied experiments in his classic report on tuberculosis—from consumptive monkeys and consumptive oxen and consumptive guinea-pigs Koch grew forty-three different families of these deadly rods on his slanted tubes of serum jelly!

And only from animals sick or dying of tuberculosis, could he grow them. For months he nursed these wee murderers along, planting them from one tube to another—with marvelous watchfulness he kept all other chance microbes away from them.

"Now I must shoot these bacilli—these pure cultivations of my bacilli—into healthy guinea-pigs, into all kinds of healthy animals. If then these creatures get tuberculosis, I shall know that my bacilli are necessarily and beyond all doubt the cause!"

That man with the terrible single-mindedness of a maniac driven by a fixed idea changed his laboratory into the weirdest kind of zoo. He became grouchy to every one—to curious visitors he was a sarcastic, spiteful little German ogre. Alone he sterilized batteries of shining syringes and shot the crinkly masses of microbes from the cultivations in his serum-jelly tubes—he injected these bacilli ground up in a little pure water into guinea-pigs and rabbits and hens and rats and mice and monkeys. "That's not enough!" he growled, "I'll try some animals that never are known to have tuberculosis naturally." So he ranged abroad and gathered to his laboratory and injected his beloved terrible bacilli into tortoises, sparrows, five frogs and three eels.

Insanely Koch completed this most fantastic test by sticking his microbes from the serum cultivation into—a goldfish!

Days dragged by, weeks passed, and every day Koch walked into his workshop in the morning and made straight for the cages and jars that held these momentous animals. The goldfish continued to open and shut his mouth and swim placidly