Microbe Hunters

by Paul De Kruif

  Then one day old Professor Balard walked into his workroom. Balard had started life as a druggist; he had been an owlish original druggist who had amazed the scientific world by making the discovery of the element bromine, not in a fine laboratory, but on the prescription counter in the back room of a drugstore. This had got him fame and his job of professor of chemistry in Paris. Balard was not ambitious; he had no yearning to make all the discoveries in the world—discovering bromine was enough for one man's lifetime—but Balard did like to nose around to watch what went on in other laboratories.

  “You say you're stuck, you say you do not see how to get air and boiled yeast soup together without getting living creatures into the yeast soup, my friend?” you can hear the lazy Balard asking the then confused Pasteur. “Look here, you and I both believe there is no such thing as microbes rising in a yeast soup by themselves—we both believe they fall in or creep in with the dust of the air, is it not so?”

  “Yes,” answered Pasteur, “but—”

  “Wait a minute!” interrupted Balard. “Why don't you just try the trick of putting some yeast soup in a bottle, boiling it, then fixing the opening so the dust can't fall in. At the same time the air can get in all it wants to.”

  “But how?” asked Pasteur.

  “Easy,” replied the now forgotten Balard. “Take one of your round flasks, put the yeast soup into it, then soften the glass of the flask neck in your blast lamp—and draw the neck out and downward into a thin little tube—turn his little tube down the way a swan bends his neck when he's picking something out of the water. Then just leave the end of the tube open. It's like this––” and Balard sketched a diagram:

  Pasteur looked, then suddenly saw the magnificent ingeniousness of this little experiment. “Why, then microbes can't fall into the flask, because the dust they stick to can't very well fall upward—marvelous! I see it now!”

  “Exactly,” smiled Balard. “Try it and find out if it works—see you later,” and he left to continue his genial round of the laboratories.

  Pasteur had bottle washers and assistants now, and he ordered them to hurry and prepare the flasks. In a moment the laboratory was buzzing with the stuttering ear-shattering b-r-r-r-r-r of the enameler's lamps; he fell to work savagely. He took flasks and put yeast soup into them and then melted their necks and drew them out and curved them downward—into swan's necks and pigtails and Chinaman's cues and a half-dozen fantastic shapes. Next he boiled the soup in them—that drove out all the air—but as the flasks cooled down new air came in—unheated air, perfectly clean air.

  The flasks ready, Pasteur crawled on his hands and knees, back and forth with a comical dignity on his hands and knees, carrying one flask at a time, through a low cubby hole under the stairs to his incubating oven. Next morning he was first at the laboratory, and in a jiffy, battered notebook in his hand, if you had been there you would have seen his rear elevation disappearing underneath the stairway. Like a beagle to its rabbit Pasteur was drawn to this oven with its swan neck flasks. Family, love, breakfast, and the rest of a silly world no longer existed for him.

  Had you still been there a half hour later you would have seen him come crawling out, his eyes shining through his fogged glasses. He had a right to be happy, for every one of the long twisty necked bottles in which the yeast soup had been boiled was perfectly clear—there was not a living creature in them. The next day they remained the same and the next. There was no doubt now that Balard's scheme had worked. There was no doubt that spontaneous generation was nonsense. “What a fine experiment is this experiment of mine—this proves that you can leave any kind of soup, after you've boiled it, you can leave it open to the ordinary air, and nothing will grow in it—so long as the air gets into it through a narrow twisty tube.”

  Balard came back and smiled as Pasteur poured the news of the experiment over him. “I thought it would work—you see, when the air comes back in, as the flask cools, the dusts and their germs start in through the narrow neck—but they get caught on the moist walls of the little tube.”

  “Yes, but how can we prove that?” puzzled Pasteur.

  “Just take one of those flasks that has been in your oven all these days, a flask where no living things have appeared, and shake that flask so that the soup sloshes over and back and forth into the swan's neck part of it. Put it back in the oven, and next morning the soup will be cloudy with thick swarms of little beasts—children of the ones that were caught in the neck.”

  Pasteur tried it, and it was so! A little later at a brilliant meeting where the brains and wit and art of Paris fought to get in, Pasteur told of his swan neck flask experiment in rapturous words. “Never will the doctrine of Spontaneous Generation recover from the mortal blow that this simple experiment has dealt it,” he shouted. If Balard was there you may be sure he applauded as enthusiastically as the rest. A rare soul was Balard.

  Then Pasteur invented an experiment that was—so far as one can tell from a careful search through the records—really his own. It was a grand experiment, a semi-public experiment, an experiment that meant rushing across France in trains, it was a test in which he had to slither around on glaciers. Once more his laboratory became a shambles of cluttered flasks and hurrying assistants and tinkling glassware and sputtering, bubbling pots of yeast soup. Pasteur and his enthusiastic slaves—they were more like fanatic monks than slaves—were getting ready hundreds of round bellied bottles. They filled each one of them part full of yeast soup and then, during many hours that shot by like moments—such was their excitement—they doused each bottle for a few minutes in boiling water. And while the soup was boiling they drew the flask necks out in a spitting blue flame until they were sealed shut. Each one of this regiment of bottles held boiled yeast soup—and a vacuum.

  Armed with these dozens of flasks, and fussing about them, Pasteur started on his travels. He went down first into the dank cellars of the Observatory of Paris, that famous Observatory where worked the great Le Verrier, who had done the proud feat of prophesying the existence of the planet Neptune. “Here the air is so still, so calm,” said Pasteur to his boys, “that there will be hardly any dust in it, and almost no microbes.” Then, holding the flasks far away from their bodies, using forceps that had been heated red hot in a flame, they cracked the necks of ten of the flasks in succession; as the neck came off each one, there was a hissing “s-s-s-s” of air rushing in. At once they sealed the bottles shut again in the flickering flame of an alcohol lamp. They did the same stunt in the yard of the observatory with another ten bottles, then hurried back to the little laboratory to crawl under the stairs to put the bottles in the incubating oven.

  A few days later Pasteur might have been seen squatting before his oven, handling his rows of flasks lovingly, laughing his triumph with one of those extremely rare laughs of his—he only laughed when he found out he was right. He put down tiny scrawls in his notebook, and then crawled out of his cubby-hole to tell his assistants: “Nine out of ten of the bottles we opened in the cellar of the Observatory are perfectly clear—not a single germ got into them. All the bottles we opened in the yard are cloudy—swarming with living creatures. It's the air that sucks them into the yeast soup—it's the dust of the air they come in with!”

  He gathered up the rest of the bottles and hurried to the train—it was the time of the summer vacation when other professors were resting—and he went to his old home in the Jura mountains and climbed the hill of Poupet and opened twenty bottles there. He went to Switzerland and perilously let the air hiss into twenty flasks on the slopes of Mont Blanc; and found, as he had hoped, that the higher he went, the fewer were the flasks of yeast soup that became cloudy with swarms of microbes. “That is as it ought to be,” he cried, “the higher and clearer the air, the less dust—and the fewer the microbes that always stick to particles of the dust.” He came back proudly to Paris and told the Academy—with proofs that would astonish everybody!—that it was now sure that air alone could never cause liv
ing things to rise in yeast soup. “Here are germs, right beside them there are none, a little further on there are different ones. . . and here where the air is perfectly calm there are none at all,” he cried. Then once more he set a new stage for possible magnificent exploits: “I would have liked to have gone up in a balloon to open my bottles still higher up!” But he didn't go up in that balloon, for his hearers were already sufficiently astonished. Already they considered him to be more than a man of science; he became for them a composer of epic searchings, a Ulysses of microbe hunters—the first adventurer of that heroic age to which you will soon come in this story.

  Many times Pasteur won his arguments by brilliant experiments that simply floored everyone, but sometimes his victories were due to the weakness or silliness of his opponents, and again they were the result of luck. Before a society of chemists Pasteur had insulted the scientific ability of naturalists; he was astonished, he shouted, that naturalists didn't stretch out a hand to the real way of doing science—that is, to experiments. “I am of the persuasion that that would put a new sap into their science,” he said. You can imagine how the naturalists liked that kind of talk; particularly M. Pouchet, director of the Museum of Rouen, did not like it and he was enthusiastically joined in not liking it by Professor Joly and Mr. Mussel, famous naturalists of the College of Toulouse. Nothing could convince these enemies of Pasteur that microscopic beasts did not come to life without parents. They were sure there was such a thing as life arising spontaneously; they decided to beat Pasteur on his own ground at his own game.

  Like Pasteur they filled up some flasks, but unlike him they used a soup of hay instead of yeast, they made a vacuum in their bottles and hastened to high Maladetta in the Pyrenees, and they kept climbing until they had got up many feet higher than Pasteur had been on Mont Blanc. Here, beaten upon by nasty breezes that howled out of the caverns of the glaciers and sneaked through the thick linings of their coats, they opened their flasks—Mr. Joly almost slid off the edge of the ledge and was only saved from a scientific martyr's death when a guide grabbed him by the coat tail! Out of breath and chilled through and through they staggered back to a little tavern and put their flasks in an improvised incubating oven—and in a few days, to their joy, they found every one of their bottles swarming with little creatures. Pasteur was wrong!

  Now the fight was on. Pasteur became publicly sarcastic about the experiments of Pouchet, Joly and Mussel; he made criticisms that to-day we know are quibbles. Pouchet came back with the remark that Pasteur “had presented his own flasks as an ultimatum to science to astonish everybody.” Pasteur was furious, denounced Pouchet as a liar and bawled for a public apology. It seemed, alas, as if the truth were going to be decided by the spilling of blood, instead of by calm experiment. Then Pouchet and Joly and Musset challenged Pasteur to a public experiment before the Academy of Sciences, and they said that if one single flask would fail to grow microbes after it had been opened for an instant, they would admit they were wrong. The fatal day for the tests dawned at last—what an interesting day it would have been—but at the last moment Pasteur's enemies backed down. Pasteur did his experiments before the Commission—he did them confidently with ironical remarks—and a little while later the Commission announced: “The facts observed by Mr. Pasteur and contested by Messrs. Pouchet, Joly and Mussel, are of the most perfect exactitude.”

  Luckily for Pasteur, but alas for Truth. Both sides happened to be right. Pouchet and his friends had used hay instead of yeast soup, and a great Englishman, Tyndall, found out years later that hay holds wee stubborn seeds of microbes that will stand boiling for hours! It was really Tyndall that finally settled this great quarrel; it was Tyndall that proved Pasteur was right.

  5

  Pasteur was now presented to the Emperor Napoleon III. He told that dreamy gentleman that his whole ambition was to find the microbes that he was sure must be the cause of disease. He was invited to an imperial house party at Compiègne. The guests were commanded to get ready to go hunting, but Pasteur begged to be excused; he had had a dray load of apparatus sent up from Paris—though he was only staying at the palace for a week!—and he impressed their Imperial Majesties enormously by bending over his microscope while everybody else was occupied with frivolous and gay amusements.

  The world must know that microbes have got to have parents! At Paris he made a popular speech at the scientific soirée at the Sorbonne, before Alexandre Dumas, the novelist, and the woman genius, George Sand, the Princess Mathilde, and a hundred more smart people. That night he staged a scientific vaudeville that sent his audience home in awe and worry; he showed them lantern slides of a dozen different kinds of germs; mysteriously he darkened the hall and suddenly shot a single bright beam of light through the blackness. “Observe the thousands of dancing specks of dust in the path of this ray,” he cried; “the air of this hall is filled with these specks of dust, these thousands of little nothings that you should not despise always, for sometimes they carry disease and death; the typhus, the cholera, the yellow fever and many other pestilences!” This was dreadful news; his audience shuddered, convinced by his sincerity. Of course this news was not strictly true, but Pasteur was no mountebank—he believed it himself! Dust and the microbes of the dust had become his life—he was obsessed with dust. At dinner, even at the smartest houses, he would hold his plates and spoons close up to his nose, peer at them, scour them with his napkin, he was with a vengeance putting microbes on the map. . .

  Every Frenchman from the Emperor down was becoming excited about Pasteur and his microbes. Whisperings of mysterious and marvelous events seeped through the gates of the Normal School. Students, even professors, passed the laboratory a little atremble with awe. One student might be heard remarking to another, as they passed the high gray walls of the Normal School in the Rue d'Ulm: “There is a man working here—his name is Pasteur—who is finding out wonderful things about the machinery of life, he knows even about the origin of life, he is even going to find out, perhaps, what causes disease. . . ” So Pasteur succeeded in getting another year added to the course of scientific studies; new laboratories began to go up; his students shed tears of emotion at the fiery eloquence of his lectures. He talked about microbes causing disease long before he knew anything about whether or not they caused disease—he hadn't yet got his fingers at the throats of mysterious plagues and dreadful deaths, but he knew there were other ways to interest the public, to arouse even such a hardheaded person as the average Frenchman.

  “I beg you,” he addressed the French people in a passionate pamphlet, “take some interest in those sacred dwellings meaningly called laboratories. Ask that they be multiplied and completed. They are the temples of the future, of riches and comfort.” Fifty years ahead of his time as a forward-looking prophet, he held fine austere ideals up to his countrymen while he appealed to their wishes for a somewhat piggish material happiness. A good microbe hunter, he was much more than a mere woolgathering searcher, much more than a mere man of science. . .

  Once more he started out to show all of France how science could save money for her industry; he packed up boxes of glassware and an eager assistant, Duclaux, and bustled off to Arbois, his old home—he hurried off up there to study the diseases of wine—to save the imperiled wine industry. He set up his laboratory in what had been an old café and instead of gas burners he had to be satisfied with an open charcoal brazier that the enthusiastic Duclaux kept glowing with a pair of bellows; from time to time Duclaux would scamper across to the town pump for water; their clumsy apparatus was made by the village carpenter and tinsmith. Pasteur rushed around to his friends of long ago and begged bottles of wine, bitter wine, ropy wine, oily wine; he knew from his old researches that it was yeasts that changed grapejuice into wine—he felt certain that it must be some other wee microscopic being that made wines go bad.

  Sure enough! When he turned his lens on to ropy wines he found them swarming with very tiny curious microbes hitched together like str
ings of beads; he found the bottles of bitter wine infested with another kind of beast and the kegs of turned wine by still another. Then he called the winegrowers and the merchants of the region together and proceeded to show them magic.

  “Bring me a half dozen bottles of wine that has gone bad with different sicknesses,” he asked them. “Do not tell me what is wrong with them, and I'll tell you what ails them without tasting them.” The winegrowers didn't believe him; among each other they snickered at him as they went to fetch the bottles of sick wine; they laughed at the fantastic machinery in the old café, they took Pasteur for some kind of earnest lunatic. They planned to fool him and brought him bottles of perfectly good wine among the sick ones. Then he set about flabbergasting them! With a slender glass tube he sucked a drop of wine out of a bottle and put it between two little slips of glass before his microscope. The wine raisers nudged each other and winked French winks of humorous common sense, while Pasteur sat hunched over his microscope, and they became more merry as minutes passed. . .

  Suddenly he looked at them and said: “There is nothing the matter with this wine—give it to the taster—let him see if I'm right”

  The taster did his tasting, then puckered up his purple nose and admitted that Pasteur was correct; and so it went through a long row of bottles—when Pasteur looked up from his microscopes and prophesied: “Bitter wine”—it turned out to be bitter; and when he foretold that the next sample was ropy, the taster acknowledged that ropy was right!'

  The wine raisers mumbled their thanks and lifted their hats to him as they left. “We don't get the way he does this—but he is a very clever man, very, very clever,” they muttered. That is much for a peasant Frenchman to admit. . .

  When they left, Pasteur and Duclaux worked triumphantly in their tumbledown laboratory; they tackled the question of how to keep these microbes out of healthy wines—they found at last that if you heat wine just after it has finished fermenting, even if you heat it gently, way below the point of boiling, the microbes that have no business in the wine will be killed—and the wine will not become sick. That little trick is now known to everybody by the name of pasteurization.