“What are these things ... are they microbes ... are they alive? They do not move ... maybe the sick blood of these poor beasts just changes into these threads and rods,” Koch pondered. Other men of science, Davaine and Rayer in France, had seen these same things in the blood of dead sheep; and they had announced that these rods were bacilli, living germs, that they were undoubtedly the real cause of anthrax--but they hadn’t proved it, and except for Pasteur, no one in Europe believed them. But Koch was not particularly interested in what anybody else thought about the threads and rods in the blood of dead sheep and cattle--the doubts and the laughter of doctors failed to disturb him, and the enthusiasms of Pasteur did not for one moment make him jump at conclusions. Luckily nobody anxious to develop young microbe hunters had ever heard of Koch, he was a lone wolf searcher--he was his own man, alone with the mysterious tangled threads in the blood of the dead beasts. “I do not see a way yet of finding out whether these little sticks and threads are alive,” he meditated, “but there are other things to learn about them....” Then, curiously, he stopped studying diseased creatures and began fussing around with perfectly healthy ones. He went down to the slaughter houses and visited the string butchers and hobnobbed with the meat merchants of Wollstein, and got bits of blood from tens, dozens, fifties of healthy beasts that had been slaughtered for meat. He stole a little more time from his tooth-pullings and professional layings-on-of-hands. More and more Mrs. Koch worried at his not tending to his practice. He bent over his microscope, hours on end, watching the drops of healthy blood. “Those threads and rods are never found in the blood of any healthy animal,” Koch pondered, “--this is all very well, but it doesn’t tell me whether they are bacilli, whether they are alive ... it doesn’t show me that they grow, breed, multiply....” But how to find this out? Consumptives--whom, alas, he could not help--babies choking with diphtheria, old ladies who imagined they were sick, all his cares of a good physician began to be shoved away into one corner of his head. How-to-prove-these-wee-sticks-are-alive, this question made him forget to sign his name to prescriptions, it made him a morose husband, it made him call the carpenter in to put up a partition in his doctor’s office. And behind this wall Koch stayed more and more hours, with his microscope and drops of black blood of sheep mysteriously dead--and with a growing number of cages full of scampering white mice. “I haven’t the money to buy sheep and cows for my experiments,” you can hear him muttering, while some impatient invalid shuffled her feet in the waiting room, “besides, cows would be a little inconvenient to have around my office--but maybe I can give anthrax to these mice ... maybe in them I can prove that the sticks really grow....”