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been cured from it either, and this serum did not hinder one bit the murderous action of the poison. He shot this mixture into new guinea-pigs; in three days they grew cold; when he laid them on their backs and poked them with his finger they did not budge. In a few hours they had coughed their last sad hiccup and passed beyond. . . .

"It is only the serum of immune animals—of beasts who have had diphtheria and have been cured of it—it is only such serum kills the diphtheria poison!" cried Behring. Healer that he was, you can hear him muttering: "Now, maybe, I can make larger animals immune too, and get big batches of their poison-killing serum, then I'll try that on children with diphtheria. . . . what saves guinea-pigs should cure babies!"

By this time nothing could discourage Behring. Like some victorious general swept on by the momentum of his first bloody success, he began shooting diphtheria microbes, and iodine tri-chloride, and the poison of diphtheria microbes, into rabbits, into sheep, into dogs. He tried to turn their living bodies into factories for making the healing serum, the toxin-killing serum. "Antitoxin" he called such serum. And he succeeded, after those maimings and holocausts and mistakes, always the necessary preludes to his triumphs. In a little while he had sheep powerfully immune, and from them he got plenty of blood. "Surely the antitoxin [he hadn't the faintest notion what the chemistry of this mysterious stuff was] certainly it will prevent diphtheria," said Behring.

He injected little doses of the sheep serum into guinea-pigs; the next day he pumped virulent diphtheria bacilli into these same beasts. It was marvelous to watch them. There they were, scampering about with never a sign of sickness, while their companions (who had got no protecting dose of serum) perished miserably in a couple of days. How good it was to see them die, those unguarded beasts! For it was these creatures told him how well the serum saved the other ones. Hundreds of pretty experiments of this kind Behring made (there