Microbe Hunters

by Paul De Kruif

  When he was twenty-six years old he made it. After long peerings at heaps of tiny crystals he discovered that there are four distinct kinds of tartaric acid instead of two; that there are a variety of strange compounds in nature that are exactly alike—excepting that they are mirror-images of each other. When he stretched his arms and straightened up his lame back and realized what he had done, he rushed out of his dirty dark little laboratory into the hall, threw his arms around a young physics assistant—he hardly knew him—and took him out under the thick shade of the Gardens of the Luxembourg. There he poured mouthfuls of triumphant explanation at him—he must tell some one. He wanted to tell the world!

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  In a month he was praised by gray-haired chemists and became the companion of learned men three times his age. He was made professor at Strasbourg and in the off moments of researches he determined to marry the daughter of the dean. He didn't know if she cared for him but he sat down and wrote her a letter that he knew must make her love him:

  “There is nothing in me to attract a young girl's fancy,” he wrote, “but my recollections tell me that those who have known me very well have loved me very much.”

  So she married him and became one of the most famous and long-suffering and in many ways one of the happiest wives in history—and this story will have more to tell about her.

  Now the head of a house, Pasteur threw himself more furiously into his work; forgetting the duties and chivalries of a bridegroom, he turned his nights into days. “I am on the verge of mysteries,” he wrote, “and the veil is getting thinner and thinner. The nights seem to me too long. I am often scolded by Madame Pasteur, but I tell her I shall lead her to fame.” He continued his work on crystals; he ran into blind alleys, he did strange and foolish and impossible experiments, the kind a crazy man might devise—and the kind that turn a crazy man into a genius when they come off. He tried to change the chemistry of living things by putting them between huge magnets. He devised weird clockworks that swung plants back and forward, hoping so to change the mysterious molecules that formed these plants into mirror images of themselves. . . He tried to imitate God: he tried to change species!

  Madame Pasteur waited up nights for him and marveled at him and believed in him, and she wrote to his father: “You know that the experiments he is undertaking this year will give us, if they succeed, a Newton or a Galileo!” It is not clear whether good Madame Pasteur formed this so high opinion of her young husband by herself. . . At any rate, truth, that will o' the wisp, failed him this time—his experiments didn't come off.

  Then Pasteur was made Professor and Dean of the Faculty of Sciences in Lille and there he settled down in the Street of the Flowers, and it was here that he ran, or rather stumbled for the first time, upon microbes; it was in this good solid town of distillers and sugar-beet raisers and farm implement dealers that he began his great campaign, part science, part drama and romance, part religion and politics, to put microbes on the map. It was from this not too interesting middle sized city—never noted for learning—that he splashed up a great wave of excitement about microbes that rocked the boat of science for thirty years. He showed the world how important microbes were to it, and in doing this he made enemies and worshipers; his name filled the front pages of newspapers and he received challenges to duels; the public made vast jokes about his precious microbes while his discoveries were saving the lives of countless women in childbirth. In short it was here he hopped off in his flight to immortality.

  When he left Strasbourg truth was tricking him and he was confused. He came to Lille and fairly stumbled on to the road to fame—by offering help to a beet-sugar distiller.

  When Pasteur settled in Lille he was told by the authorities that highbrow science was all right—

  “But what we want, what this enterprising city of Lille wants most of all, professor,” you can hear the Committee of business men telling him, “is a close cooperation between your science and our industries. What we want to know is—does science pay? Raise our sugar yield from our beets and give us a bigger alcohol output, and we'll see you and your laboratory are taken care of.”

  Pasteur listened politely and then proceeded to show them the stuff he was made of. He was much more than a man of science! Think of a committee of business men asking Isaac Newton to show them how his laws of motion were going to help their iron works! That shy thinker would have thrown up his hands and set himself to studying the meaning of the prophecies of the Book of Daniel at once. Faraday would have gone back to his first job as a bookbinder's apprentice. But Pasteur was no shrinking flower. A child of the nineteenth century, he understood that science had to earn its bread and butter, and he started to make himself popular with everybody by giving thrilling lectures to the townspeople on science:

  “Where in your families will you find a young man whose curiosity and interest will not immediately be awakened when you put into his hands a potato, and when with that potato he may produce sugar, and with that sugar alcohol, and with that alcohol ether and vinegar?” he shouted enthusiastically one evening to an audience of prosperous manufacturers and their wives. Then one day Mr. Bigo, a distiller of alcohol from sugar beets, came to his laboratory in distress. “We're having trouble with our fermentations, Professor,” he complained; “we're losing thousands of francs every day. I wonder if you could come over to the factory and help us out?” said the good Bigo.

  Bigo's son was a student in the science course and Pasteur hastened to oblige. He went to the distillery and sniffed at the vats that were sick, that wouldn't make alcohol; he fished up some samples of the grayish slimy mess and put them in bottles to take to his laboratory—and he didn't fail to take some of the beet pulp from the healthy foamy vats where good amounts of alcohol were being made. Pasteur had no idea he could help Bigo, he knew nothing of how sugar ferments into alcohol—indeed, no chemist in the world knew anything about it. He got back to his laboratory, scratched his head, and decided to examine the stuff from the healthy vats first He put some of this stuff—a drop of it—before his microscope, maybe with an aimless idea of looking for crystals, and he found this drop was full of tiny globules, much smaller than any crystal, and these little globes were yellowish in color, and their insides were full of a swarm of curious dancing specks.

  “What can these things be,” he muttered. Then suddenly he remembered—

  “Of course, I should have known—these are the yeasts you find in all stews that have sugar which is fermenting into alcohol!”

  “He looked again and saw the wee spheres alone; he saw some in bunches, others in chains, and then to his wonder he came on some with queer buds sprouting from their sides—they looked like sprouts on infinitely tiny seeds.

  “Cagniard de la Tour is right. These yeasts are alive. It must be the yeasts that change beet sugar into alcohol!” he cried. “But that doesn't help Mr. Bigo—what on earth can be the matter with the stuff in the sick vats?” He grabbed for the bottle that held the stuff from the sick vat, he sniffed at it, he peered at it with a little magnifying glass, he tasted it, he dipped little strips of blue paper in it and watched them turn red. . . Then he put a drop from it before his microscope and looked. . .

  “But there are no yeasts in this one; where are the yeasts? There is nothing here but a mass of confused stuff—what is it, what does this mean?” He took the bottle up again and brooded over it with an eye that saw nothing—till at last a different, a strange look of the juice forced its way up into his wool-gathering thoughts. “Here are little gray specks sticking to the walls of the bottle—here are some more floating on the surface—wait! No, there aren't any in the healthy stuff where there are yeasts and alcohol. What can that mean?” he pondered. Then he fished down into the bottle and got a speck, with some trouble, into a drop of pure water; he put it before his microscope. . .

  His moment had come.

  No yeast globes here, no, but something different, something strange he had never seen before, great
tangled dancing masses of tiny rod-like things, some of them alone, some drifting along like strings of boats, all of them shimmying with a weird incessant vibration. He hardly dared to guess at their size—they were much smaller than the yeasts—they were only one-twenty-five-thousandth of an inch long!

  That night he tossed and didn't sleep and next morning his stumpy legs hurried him back to the beet factory. His glasses awry on his nearsighted eyes, he leaned over and dredged up other samples from other sick vats—he forgot all about Bigo and thought nothing of helping Bigo; Bigo didn't exist; nothing in the world existed but his sniffing curious self and these dancing strange rods. In every one of the grayish specks he found millions of them. . . Feverishly at night with Madame Pasteur waiting up for him and at last going to bed without him, he set up apparatus that made his laboratory look like an alchemist's den. He found that the rod-swarming juice from the sick vats always contained the acid of sour milk—and no alcohol. Suddenly a thought flooded through his brain: “Those little rods in the juice of the sick vats are alive, and it is they that make the acid of sour milk—the rods fight with the yeasts perhaps, and get the upper hand. They are the ferment of the sour-milk-acid, just as the yeasts must be the ferment of the alcohol!” He rushed up to tell the patient Madame Pasteur about it, the only half-understanding Madame Pasteur who knew nothing of fermentations, the Madame Pasteur who helped him so by believing always in his wild enthusiasms. . .

  It was only a guess but there was something inside him that whispered to him that it was surely true. There was nothing uncanny about the rightness of his guess; Pasteur made thousands of guesses about the thousand strange events of nature that met his shortsighted peerings. Many of these guesses were wrong—but when he did hit on a right one, how he did test it and prove it and sniff along after it and chase it and throw himself on it and bring it to earth! So it was now, when he was sure he had solved the ten-thousand-year-old mystery of fermentation.

  His head buzzed with a hundred confused plans to see if he was really right, but he never neglected the business men and their troubles, or the authorities or the farmers or his students. He turned part of his laboratory into a manure testing station, he hurried to Paris and tried to get himself elected to the Academy of Sciences—and failed—and he took his classes on educational trips to breweries in Valenciennes and foundries in Belgium. In the middle of this he felt sure, one day, that he had a way to prove that the little rods were alive, that in spite of their miserable littleness they did giant's work, the work no giant could do—of changing sugar into lactic acid.

  “I can't study these rods that I think are alive in this mixed-up mess of the juice of the beet-pulp from the vats,” Pasteur pondered. “I shall have to invent some kind of clear soup for them so that I can see what goes on—I'll have to invent this special food for them and then see if they multiply, if they have young, if a thousand of the small dancing beings appears where there was only one at first.” He tried putting some of the grayish specks from the sick vats into pure sugar water. They refused to grow in it. “The rods need a richer food,” he meditated, and after many failures he devised a strange soup; he took some dried yeast and boiled it in pure water and strained it so that it was perfectly dear, he added an exact amount of sugar and a little carbonate of chalk to keep the soup from being acid. Then on the point of a fine needle he fished up one of the gray specks from some juice of a sick fermentation. Carefully he sowed this speck in his new clear soup—and put the bottle in an incubating oven—and waited, waited anxious and nervous; it is this business of experiments not coming off at once that is always the curse of microbe hunting.

  He waited and signed some vouchers and lectured to students and came back to peer into his incubator at his precious bottle and advised farmers about their crops and fertilizers and bolted absent-minded meals and peered once more at his tubes—and waited. He went to bed without knowing what was happening in his bottle—it is hard to sleep when you do not know such things. . .

  All the next day it was the same, but toward evening when his legs began to be heavy with failure once more, he muttered: “There is no clear broth that will let me see these beastly rods growing—but I'll just look once more—”

  He held the bottle up to the solitary gaslight that painted grotesque giant shadows of the apparatus on the laboratory walls. “Sure enough, there's something changing here,” he whispered; “there are rows of little bubbles coming up from some of the gray specks I sowed in the bottle yesterday—there are many new gray specks—all of them are sprouting bubbles!” Then he became deaf and dumb and blind to the world of men; he stayed entranced before his little incubator; hours floated by, hours that might have been seconds for him. He took up his bottle caressingly; he shook it gently before the light—little spirals of gray murky cloud curled up from the bottom of the flask and from these spirals came big bubbles of gas. Now he would find out!

  He put a drop from the bottle before his microscope. Eureka! The field of the lens swarmed and vibrated with shimmying millions of the tiny rods. “They multiply! They are alive!” he whispered to himself, then shouted: “Yes, I'll be up in a little while!” to Madame Pasteur who had called down begging him to come up for dinner, to come for a little rest. For hours he did not come.

  Time and again in the days that followed he did the same experiment, putting a tiny drop from a flask that swarmed with rods into a fresh clear flask of yeast soup that had none at all—and every time the rods appeared in billions and each time they made new quantities of the acid of sour milk. Then Pasteur burst out—he was not a patient man—to tell the world. He told Mr. Bigo it was the little rods that made his fermentations sick: “Keep the little rods out of your vats and you'll always get alcohol, Mr. Bigo.” He told his classes about his great discovery that such infinitely tiny beasts could make acid of sour milk from sugar—a thing no mere man had ever done or could do. He wrote the news to his old Professor Dumas and to all his friends and he read papers about it to the Lille Scientific Society and sent a learned treatise to the Academy of Sciences in Paris. It is not clear whether Mr. Bigo found it possible to keep the little rods out of his vats—for they were like bad weeds that get into gardens. But to Pasteur that didn't matter so much. Here was the one important fact:

  It is living things, sub-visible living beings, that are the real cause of fermentations!

  Innocently he told every one that his discovery was remarkable—he was too much of a child to be modest—and from now on and for years these little ferments filled his sky; he ate and slept and dreamed and loved—after his absent-minded fashion—with his ferments by him. They were his life.

  He worked alone for he had no assistant, not even a boy to wash his bottles for him; how then, you will ask, did he find time to cram his days with such a bewildering jumble of events? Partly because he was an energetic man, and partly it was thanks to Madame Pasteur, who in the words of Roux, “loved him even to the point of understanding his work.” On those evenings when she wasn't waiting up lonely for him—when she had finished putting to bed those children whose absent-minded father he was—this brave lady sat primly on a straight-backed chair at a little table and wrote scientific papers at his dictation. Again, while he was below brooding over his tubes and bottles she would translate the cramped scrawls of his notebooks into a clear beautiful handwriting. Pasteur was her life and since Pasteur thought only of work her own life melted more and more into his work. . .

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  Then one day in the midst of all this—they were just nicely settled in Lille—he came to her and said: “We are going to Paris, I have just been made Administrator and Director of Scientific Studies in the Normal School. This is my great chance.”

  They moved there, and Pasteur found there was absolutely no place for him to work in; there were a few dirty laboratories for the students but none for the professors; what was worse, the Minister of Instruction told him there was not one cent in the budget for those bottles and ovens
and microscopes without which he could not live. But Pasteur snooped round in every cranny of the dirty old building and at last climbed tricky stairs to a tiny room where rats played, to an attic under the roof. He chased the rats out and proclaimed this den his laboratory; he got money—in some mysterious way that is still not clear—for his microscopes and tubes and flasks. The world must know how important ferments are in its life. The world soon knew!

  His experiment with the little rods that made the acid of sour milk convinced him—why, no one can tell—that other kinds of small beings did a thousand other gigantic and useful and perhaps dangerous things in the world. “It is those yeasts that my microscope showed me in the healthy beet vats, it is those yeasts that turn sugar into alcohol—it is undoubtedly yeasts that make beer from barley and it is certainly yeasts that ferment grapes into wine—I haven't proved it yet, but I know it.” Energetically he wiped his fogged spectacles and cheerfully he climbed to his attic. Experiments would tell him; he must make experiments; he must prove to himself he was right—more especially he must prove to the world he was right. But the world of science was against him.

  Liebig, the great German, the prince of chemists, the pope of chemistry, was opposed to his idea. “So Liebig says yeasts have nothing to do with the turning of sugar into alcohol—so he claims that you have to have albumen there, and that it is just the albumen breaking down that carries the sugar along down with it, into alcohol.” He would show this Liebig! Then a trick to beat Liebig flashed into his head, a crafty trick, a simple clear experiment that would smash Liebig and all other pooh-bahs of chemistry who scorned the important work that his precious microscopic creatures might do.