It was beastly! All of this fussing with the delicate filter experiments--and the animals munched at the greens in their cages, they hopped about, males sniffed at females and engaged in those absurd scufflings with other males which guinea-pigs and rabbits hold to be necessary to the propagation of their kind.... Let these giants (who fed them well) inject more of this stuff into their veins, their bellies--poison? Imagination! It made them feel happy.... Roux tried again. He shot bigger doses of his filtered soup into the animals, other animals, still more animals. It was no go, there was no poison. That is, for a merely sensible man there would have been no poison in the filtered soup that had stood in the incubator for four days. Hadn’t enough animals been wasted trying it? But Roux (let all mothers and children and the gods caring for insane searchers bless him!) was no reasonable man just then. For a moment he had caught Pasteur’s madness, his strange trick of knowing what all men thought wrong to be right, his flair for good impossible experiments. “There is a poison there!” you can hear that hawk-faced consumptive Roux shout to himself, to the dusty, bottle-loaded shelves of his laboratory, to the guinea-pigs who would have snickered--if they could have--at his earnest futile efforts to murder them. “There must be a poison in this soup where the diphtheria germs have grown--else why should those rabbits have died?” Then--I have told scientific searchers about this and they have held their noses at such an experiment--Roux nearly drowned a guinea-pig. For weeks he had been injecting more and more of his filtered soup, but now (it was like facing a night on a park bench with your last dime on the two dice) he injected thirty times as much! Not even Pasteur would have risked such an outlandish dose--thirty-five cubic centimeters Roux shot under the guinea-pig’s skin and you would expect that much water would kill such a little beast. If he died it would mean nothing.... But into the belly of a guinea-pig and into the ear-vein of a rabbit went this ocean of filtered juice--it was as if he had put a bucketful of it into the veins of a middle-sized man. But that was the way Roux carved his name on those tablets which men while they are on earth must never allow to crumble; for, though the rabbit and the guinea-pig stood the mere bulk of the microbe-less broth very well, and appeared perfectly chipper for a day or so afterwards, in forty-eight hours their hair was on end, their breath began to come in little hiccups. In five days they were dead, with exactly those symptoms their brothers had, after injections of the living diphtheria bacilli. So it was that Émile Roux discovered the diphtheria poison....