Microbe Hunters

What he saw that day starts this history. Leeuwenhoek was a maniac observer, and who but such a strange man would have thought to turn his lens on clear, pure water, just come down from the sky? What could there be in water but just—water? You can imagine his daughter Maria—she was nineteen and she took such care of her slightly insane father!—watching him take a little tube of glass, heat it red hot in a flame, draw it out to the thinness of a hair.... Maria was devoted to her father—let any of those stupid neighbors dare to snigger at him!—but what in the world was he up to now, with that hair-fine glass pipe?

You can see her watch that absent-minded wide-eyed man break the tube into little pieces, go out into the garden to bend over an earthen pot kept there to measure the fall of the rain. He bends over that pot. He goes back into his study. He sticks the little glass pipe onto the needle of his microscope....

What can that dear silly father be up to?

He squints through his lens. He mutters guttural words under his breath....

Then suddenly the excited voice of Leeuwenhoek: “Come here! Hurry! There are little animals in this rain water.... They swim! They play around! They are a thousand times smaller than any creatures we can see with our eyes alone.... Look! See what I have discovered!”

What was this that rose from the gray dimness of his lens into clear distinctness as he brought the tube into the focus? Here was an unbelievably tiny creature, leaping about in the water of the tube “like the fish called a pike.” There was a second kind that swam forward a little way, then whirled about suddenly, then tumbled over itself in pretty somersaults. There were some beings that moved sluggishly and looked like wee bent sticks, nothing more, but that Dutchman squinted at them till his eyes were red-rimmed—and they moved, they were alive, no doubt of it! There was a menagerie in his mouth! There were creatures shaped like flexible rods that went to and fro with the stately carriage of bishops in procession, there were spirals that whirled through the water like violently animated corkscrews....

Everybody he could get hold of—as well as himself—was an experimental animal for that curious man. Tired from his long peering at the little beasts in his own mouth, he went for a walk under the tall trees that dropped their yellow leaves on the brown mirrors of the canals; it was hard work, this play of his, he must rest! But he met an old man, a most interesting old man: “I was talking to this old man,” wrote Leeuwenhoek to the Royal Society, “an old man who led a very sober life, who never used brandy nor tobacco and very seldom wine, and my eye chanced to fall on his teeth which were badly grown over and that made me ask him when he had last cleaned his mouth.

On a day in October in 1831, a nine-year-old boy ran frightened away from the edge of a crowd that blocked the door of the blacksmith shop of a village in the mountains of eastern France. Above the awed excited whispers of the people at the door this boy had heard the crackling “s-s-s-s-z” of a white hot iron on human flesh, and this terrifying sizzling had been followed by a groan of pain. The victim was the farmer Nicole. He had just been mangled by a mad wolf that charged howling, jaws dripping poison foam, through the streets of the village. The boy who ran away was Louis Pasteur, son of a tanner of Arbois and great-grandson of a serf of the Count of Udressier.

Days and weeks passed and eight victims of the mad wolf died in the choking throat-parched agonies of hydrophobia. Their screams rang in the ears of this timid—some called him stupid—boy; and the iron that had seared the farmer’s wound burned a deep scar in his memory.

“What makes a wolf or a dog mad, father—why do people die when mad dogs bite them?” asked Louis. His father the tanner was an old sergeant of the armies of Napoleon. He had seen ten thousand men die from bullets, but he had no notion of why people die from disease. “Perhaps a devil got into the wolf, and if God wills you are to die, you will die, there is no help for it,” you can hear the pious tanner answer.

“Nothing can get into that drop—only the rods are there—now we’ll see if they will grow,” whispered Koch as he slid his hanging-drop under the lens of his microscope; in a kind of stolid excitement he pulled up his chair and sat down to watch what would happen. In the gray circle of the field of his lens he could see only a few shreddy lumps of mouse spleen—they looked microscopically enormous—and here and there a very tiny rod floated among these shreds. He looked—fifty minutes out of each hour for two hours he looked, and nothing happened. But then a weird business began among the shreds of diseased spleen, an unearthly moving picture, a drama that made shivers shoot up and down his back.

The little drifting rods had begun to grow! Here were two where one had been before. There was one slowly stretching itself out into a tangled endless thread, pushing its snaky way across the whole diameter of the field of the lens—in a couple of hours the dead small chunks of spleen were completely hidden by the myriads of rods, the masses of thread that were like a hopelessly tangled ball of colorless yarn, living yarn—silent murderous yarn.

“Now I know that these rods are alive,” breathed Koch. “Now I see the way they grow into millions in my poor little mice—in the sheep, in the cows even.

dreadful convulsions, but the other four would go on chewing their greens as if there were no mad-dog virus within a million miles of them.

Then one day a little idea came to Pasteur, and he hurried to tell it to Roux.

“This rabies virus that gets into people by bites, it settles in their brains and spinal cords.... All the symptoms of hydrophobia show that it’s the nervous system that this virus—this bug we can’t find—attacks....

“That’s where we have to look for the unknown microbe ... that’s where we can grow it maybe, even without seeing it ... maybe we could use the living animal’s brain instead of a bottle of soup ... a funny culture-bottle that would be, but....

“When we inject it under the skin—the virus may get lost in the body before it can travel to the brain—if I could only stick it right into a dog’s brain...!”

Roux listened to these dreamings of Pasteur, he listened bright-eyed to these fantastic imaginings.... Another man than Roux might have thought Pasteur completely crazy.... The brain of a dog or rabbit instead of a bottle of broth, indeed! What nonsense! But not to Roux!

“But why not put the virus right into a dog’s brain, master, I can trephine a dog—I can drill a little hole in his skull—without hurting him—without damaging his brain at all ... it would be easy ...” said Roux.

Pasteur shut Roux up, furiously. He was no doctor, and he did not know that surgeons can do this operation on human beings even, quite safely. “What! bore a hole right through a dog’s skull—why, you’d hurt the poor beast terribly ... you would damage his brain ... you would paralyze him.... No! I will not permit it!”