If old Leeuwenhoek, two hundred years before, had made so astounding a discovery, Europe of the Seventeenth Century would have heard the news in months. But in 1882 the news that Robert Koch had found the microbe of tuberculosis trickled out of the little room of the Physiological Society the same evening, sang to Kamchatka and to San Francisco on the cable wires that night, and exploded on the front pages of the newspapers in the morning. Then the world went wild over Koch, doctors boarded ships and hopped trains for Berlin to learn from him the secret of hunting microbes; vast crowds of them rushed to Berlin to sit at Koch’s feet to learn how to make beef-broth jelly and how to stick syringes full of germs into the wiggling carcasses of guinea-pigs. Pasteur’s deeds had set France by the ears, but Koch’s experiments with the dangerous tubercle bacilli rocked the earth, and Koch waved worshipers away, saying: “This discovery of mine is not such a great advance.” He tried to get away from his adorers and to dodge his eager pupils, to snatch what moments he could for his own new searchings. He loathed teaching--that way he was precisely like Leeuwenhoek--but he was forced, cursing under his breath, to give lessons in microbe hunting to Japanese who spoke horrible German and understood less than they spoke, and to Portuguese, who could never, by any amount of instruction, learn to hunt microbes. He started a huge fight with Pasteur--but of this I shall tell in the next chapter--and between times he showed his assistant, Gaffky, how to spy on and track down the bacillus of typhoid fever. He was forced to attend idiotic receptions and receive medals, and came away from these occasions to guide his fierce-mustached assistant Loeffler, who was on the trail of the poison-dripping microbe that kills babies with diphtheria. It was thus that Koch shook the tree of his marvelous simple method of growing microbes on the surface of solid food--he shook the tree, as Gaffky said long afterward, and discoveries rained into his lap. In all of his writings I have never found any evidence that Koch considered himself a great originator; never, like Pasteur, did he seem to realize that he was the leader in the most beautiful and one of the most thrilling battles of men against cruel nature--there was no actor in this mussy-bearded little man. But he did set under way an inspiring drama, a struggle with the messengers of death that turned some of the microbe-hunting actors into maniac searchers, men who went to nearly suicidal lengths, almost murderous extremes--to prove that microbes were the cause of dangerous diseases.