“We will change it a little,” said Paul Ehrlich, though he knew the chemists who had invented Atoxyl had said it was so built that it couldn’t be changed without spoiling it. But every afternoon Ehrlich fussed around alone in his chemical laboratory, which was like no other chemical laboratory in the world. It had no retorts, no beakers, no flasks nor thermometers nor ovens--no, not even a balance! It was crude as the prescription counter of the country druggist (who also runs the postoffice) excepting that in its middle stood a huge table, with ranks and ranks of bottles--bottles with labels and bottles without, bottles with scrawled unreadable labels and bottles whose purple contents had slopped all over the labels. But that man’s memory remembered what was in every one of those bottles! From the middle of this jungle of bottles a single Bunsen burner reared its head and spouted a blue flame. What chemist would not laugh at this laboratory? Here Paul Ehrlich dabbled with Atoxyl, shouting: “Splendid!”, growling: “Un-be-liev-a-ble!”, dictating to the long-suffering Miss Marquardt, bawling for the indispensable Kadereit. In that laboratory, with a chemical cunning the gods sometimes bestow on searchers who could never be chemists, Paul Ehrlich found _that you can change Atoxyl_, not a little but a lot, that it can be built into heaven knows how many entirely unheard-of compounds of arsenic, without spoiling the combination of benzene and arsenic at all! “I can change Atoxyl!” Without his hat or coat Ehrlich hurried out of this dingy room to the marvelous workshop of Bertheim, chief of his chemist slaves. “Atoxyl can be changed--maybe we can change it into a hundred, a thousand new compounds of arsenic!” he exclaimed.... “Now, my dear Bertheim,” and he poured out a thousand fantastic schemes. Bertheim? He could not resist that “Now my dear Bertheim!” For the next two years the whole staff, Japs and Germans, not to mention some Jews, men and white rats and white mice, not to mention Miss Marquardt and Miss Leupold--and don’t forget Kadereit!--toiled together in that laboratory which was like a subterranean forge of imps and gnomes. They tried this, they did that, with six hundred and six--that is their exact number--different compounds of arsenic. Such was the power of the chief imp over them, that this staff never stopped to think of the absurdity and the impossibility of their job, which was this: to turn arsenic from a pet weapon of murderers into a cure which no one was sure could exist for a disease Ehrlich hadn’t even dreamed might be cured. These slaves worked as only men can work when they are inspired by a wrinkle-browed fanatic with kind gray eyes.