He was everywhere in the Georg Speyer House. He directed the making of compounds that would be still more wonderful--so he hoped. He chased around so that even Kadereit couldn’t keep track of him. He dictated hundreds of enthusiastic letters to Martha Marquardt, he read thousands of letters from every corner of the world, he kept records, careful records they were too, of every one of the sixty-five thousand doses of salvarsan injected in the year 1910. He kept them--this was like that strangely systematic man!--on a big sheet of paper tacked to the inside of the cupboard door of his office, from the top to the bottom of that door in tiny scrawls, so that he had constantly to squat on his heels or stretch up on tiptoe and strain his eyes to read them. As the list grew, there were records of most extraordinary cures, but there were reports it was not pleasant to read, too, records that told of hiccups and vomitings and stiffenings of legs and convulsions and death--every now and then a death in people who had no business dying, coming right after injections of the salvarsan. How he worked to explain them! How he wore himself to a shred to avoid them, for Paul Ehrlich was not a hard-boiled man. He made experiments; he conducted immense correspondences in which he asked minute questions of just how the injections had been made. He devised explanations, on the margins of the playing cards he used for his games of solitaire each evening, on the backs of those blood-and-thunder murder mysteries that were the one thing he read--so he imagined--to rest. But he never rested! Those disasters pursued him and marred his triumph.... The wrinkles deepened to ditches on his forehead. The circles darkened under those gray eyes that still, but not so often, danced with that owlish humor. So this compound six hundred and six, saving its thousands from death, from insanity, from the ostracism worse than death that came to those sufferers whose bodies the pale spirochete gnawed until they were things for loathing, this 606 began killing its tens. Paul Ehrlich wore his too feeble body to a shadow, trying to explain a mystery too deep for explanation. There is no light on that mystery now, ten years after Ehrlich smoked the last of his black cigars. So it was that this triumph of Paul Ehrlich was at the same time the last disproof of his theories, which were so often wrong. “Compound six hundred and six unites chemically with the spirochetes and kills them--it does not unite chemically with the human body and so can do no damage!” That had been his theory....