But particularly, Emil Behring was there. He was a little over thirty; he was an army doctor; he had a little beard, neater than Koch’s scraggly one, but with less signs of originality. Just the same Behring’s head, in spite of that prosaic beard, was the head of a poet; and yet, though he was fond of rhetoric, no one stuck closer to his laboratory bench than Behring. He compared the grandeur of the Master’s discovery of the tubercle bacillus to the rosy tip of the snow-capped peak of his favorite mountain in Switzerland, while he probed by careful experiments into why animals are immune to microbes. He compared the stormy course of human pneumonia to the rushing of a mountain stream, while he discovered a something in the blood of rats--this stuff would kill anthrax bacilli! He had two scientific obsessions, which were also poetical: one was that blood is the most marvelous of the juices circulating in living things (what an extraordinary mysterious sap it was, this blood!)--the other was the strange notion (not a new one) that there must exist chemicals to wipe invading microbes out of animals and men--without hurting the men or the animals. “I will find a chemical to cure diphtheria!” he cried, and inoculated herds of guinea-pigs with cultivations of virulent diphtheria bacilli. They got sick, and as they got sicker he shot various chemical compounds into them. He tried costly salts of gold, he tried naphthylamine, he tested more than thirty different strange or common substances. He believed innocently because these things could kill microbes in a glass tube without damaging the tube, they would also hit the diphtheria bacilli under a guinea-pig’s hide without ruining the guinea-pig. But alas, from the slaughter house of dead and dying guinea-pigs his laboratory was, you would suppose he would have seen there was little to choose between the deadly microbes and his equally murderous cures.... Nevertheless, being a poet, Behring did not have too great a reverence for facts; the hecatombs of corpses went on piling up, but they failed to shake his faith in some marvelous unknown remedy for diphtheria hidden somewhere among the endless rows of chemicals in existence. Then, in his enthusiastic--but random--search he came upon the tri-chloride of iodine.