Like the good hunter that he was, he took a chance with the dangers that he couldn’t avoid. He built a big box and put guinea-pigs and mice and rabbits inside it and set this box in the garden. Then through the window he ran a lead pipe that opened in a spray nozzle inside the box, and for three days, for half an hour each day, he sat in his laboratory, pumping at a pair of bellows that shot a poisonous mist of bacilli into the box--to be breathed by the cavorting beasts inside it. In ten days three of the rabbits were gasping, fighting for that precious air that their sick lungs could no longer give them. In twenty-five days the guinea-pigs had done their humble work--one and all they were dead, of tuberculosis. Koch told nothing of the ticklish job it was to take these beasts out of their germ-soaked box--if I had been in his place I would rather have handled a boxful of boa-constrictors--and he makes no mention of how he disposed of this little house whose walls had been wet with this so-deadly spray. What chances for making heroic flourishes were missed by this quiet Koch! VII On the twenty-fourth of March in 1882 in Berlin there was a meeting of the Physiological Society in a plain small room made magnificent by the presence of the most brilliant men of science in Germany. Paul Ehrlich was there and the most eminent Professor Rudolph Virchow--who had but lately sniffed at this crazy Koch and his alleged bacilli of disease--and nearly all of the famous German battlers against disease were there. A bespectacled wrinkled small man rose and put his face close to his papers and fumbled with them. The papers quivered and his voice shook a little as he started to speak. With an admirable modesty Robert Koch told these men the plain story of the way he had searched out the invisible assassin of one human being out of every seven that died. With no oratorical raisings of his voice he told these disease fighters that the physicians of the world were now able to learn all of the habits of this bacillus of tuberculosis--this smallest but most savage enemy of men. Koch recited to them the lurking places of this slim microbe, its strengths and weaknesses, and he showed them how they might begin the fight to crush, to wipe out this sub-visible deadly enemy. At last Koch sat down, to wait for the discussion, the inevitable arguments and objections that greet the finish of revolutionary papers. But no man rose to his feet, no word was spoken, and finally eyes began to turn toward Virchow, the oracle, the Tsar of German science, the thunderer whose mere frown had ruined great theories of disease. All eyes looked at him, but Virchow got up, put on his hat, and left the room--he had no word to say.