Microbe Hunters

by Paul De Kruif

  He started out to follow Manson's orders. He captured mosquitoes, any kind of mosquito, he couldn't for the life of him have told you what kind they were. He let the pests loose under nets over beds on which lay naked and foolishly superstitious dark-skinned people of a caste so low that they had no proper right to have emotions. The blood of these people was charmingly full of malaria microbes. The mosquitoes hummed under the nets—and wouldn't bite. Curse it! They could not be made to bite! “They are stubborn as mules,” wrote Ross, in agony, to Patrick Manson. But he kept at it. He cajoled the mosquitoes. He pestered the patients. He put them in the hot sun “to bring their flavor out.” The mosquitoes kept on humming and remained sniffish. But, eureka! At last he hit on the idea of pouring water over the nets, soaking the nets—also the patients, but that was no matter—and finally the mosquitoes got to work and sucked their fill of Hindu blood. Ronald Ross caught them then, put them gingerly in bottles, then day after day killed them and peeped into their stomachs to see if those malaria microbes they had sucked in with the blood might be growing. They didn't grow!

  He bungled. He was like any tyro searcher—only his innate hastiness made him worse—and he was constantly making momentous discoveries that turned out not to be discoveries at all. But his bunglings had fire in them. To read his letters to Patrick Manson, you would think he had made himself miraculously small and crawled under the lens into that blood among the objects he was learning to spy upon. And what was best, everything was a story to him, no, more than a story, a melodrama. Manson had told him to watch those strange whips that grew out of the crescent malaria germs and made them look like octopuses. In vast excitement he wrote a long letter to Manson, telling of a strange fight between a whip that had shaken itself free, and a white blood cell—a phagocyte. He was a vivid man, was Ronald Ross. “He [Ross called that whip ”he“] kept poking the phagocyte in the ribs (!) in different parts of his body, until the phagocyte finally turned and ran off howling. . . the fight between the whip and the phagocyte was wonderful. . . I shall write a novel on it in the style of the 'Three Musketeers.' ” That was the way he kept himself at it and got himself past the first ambushes and disappointments of his ignorance and inexperience. He collected malarious Hindus as a terrier collects rats. He loved them if they were shot full of malaria, he detested them when they got better. He gloried in the wretched Abdul Wahab, a dreadful case. He pounced on Abdul and dragged him from pillar to post. He put fleas on him. He tortured him with mosquitoes. He failed. He kept at it. He wrote to Manson: “Please send me advice. . . ” He missed important truths that lay right under his nose—that yelled to be discovered. But he was beginning to know just exactly what a malaria parasite looked like—he could spot its weird black grains of pigment, and tell them apart from all of the unknown tiny blobs and bubbles and balloons that drifted before his eyes under his lens. And the insides of the stomachs of mosquitoes? They were becoming as familiar as the insides of this nasty hot quarters!

  What an incredible pair of searchers they were! Away in London Patrick Manson kept answering Ross's tangled tortured letters, felt his way and gathered hope from his mixed-up accounts of unimportant experiments. “Let mosquitoes bite people sick with malaria,” wrote Manson, “then put those mosquitoes in a bottle of water and let them lay eggs and hatch out grubs. Then give that mosquito-water to people to drink. . .”

  So Ross fed some of this malaria-mosquito soup to Lutchman, his servant, and almost danced with excitement as the man's temperature went up—but it was a false alarm, it wasn't malaria, worse luck. . . So dragged the dreary days, the months, the years, feeding people mashed-up mosquitoes and writing to Manson: “I have a sort of feeling it will succeed—I feel a kind of religious excitement over it!” But it never succeeded. But he kept at it. He intrigued to get to places where he might find more malaria; he discovered strange new mosquitoes and from their bellies he dredged up unheard-of parasites—that had nothing to do with malaria. He tried everything. He was illogical. He was anti-scientific. He was like Edison combing the world to get proper stuff out of which to make phonograph needles. “There is only one method of solution,” he wrote, “that is, by incessant trial and exclusion.” He wrote that, while the simple method lay right under his hand, unfelt.

  He wrote shrieking poems called “Wraths.” He was ordered to Bangalore to try to stop the cholera epidemic, and didn't stop it. He became passionate about the Indian authorities. “I wish I might rub their noses in the filth and disease which they so impotently let fester in Hindustan,” Ronald Ross cried. But who can blame him? It was hot there. “I was now forty years old,” he wrote, “but, though I was well known in India, both for my sanitary work at Bangalore and for my researches on malaria I received no advancement at all for my pains.”

  4

  So passed two years, until, in June of 1897 Ronald Ross came back to Secunderabad, to the steamy hospital of Begumpett. The monsoon bringing its cool rain should have already broken, but it had not. A hellish wind blew gritty clouds of dust into the laboratory of Ronald Ross. He wanted to throw his microscope out of the window. Its one remaining eyepiece was cracked, and its metal work was rusted with his sweat. There was the punka, the blessed punka, but he could not start the punka going because it blew his dead mosquitoes away, and in the evening when the choking wind had died, the dust still hid the sun in a dreadful haze. Ronald Ross wrote:

  What ails the solitude?

  Is this the judgment day?

  The sky is red as blood

  The very rocks decay.

  And that relieved him and released him, just as another man might escape by whiskey or by playing bottle-pool, and on the sixteenth of August he decided to begin his work all over, to start, in short, where he had begun in 1895—“only much more thoroughly this time.” So he stripped his malaria patient—it was the famous Husein Khan. Under the mosquito net went Husein, for Ronald Ross had found a new kind of mosquito with which to plague this Husein Khan, and in his unscientific classification Ross called this mosquito, simply, a brown mosquito. (For the purposes of historical accuracy, and to be fair to Battista Grassi, I must state that it is not clear where these brown mosquitoes came from. In the early part of his report Ronald Ross says he raised them from the grubs—but a moment later, speaking of a closely related mosquito, he says: “I have failed in finding their grubs also.”)

  It is no wonder—though lamentable for the purposes of history—that Ronald Ross was mixed up, considering his lone-wolf work and that hot wind and his perpetual failures! Anyway, he took those brown mosquitoes (which may have bitten other beasts, who knows) and loosed them out of their bottles under the net. They sucked the blood of Husein Khan, at a few cents per suck per mosquito, and then once more, one day after another, Ross peeped at the stomachs of those insects.

  On the nineteenth of August he had only three of the brown beasts left. He cut one of them up. Hopelessly he began to look at the walls of its stomach, with its pretty, regular cells arranged like stones in a paved road. Mechanically he peered down the tube of his microscope, when suddenly something queer forced itself up into the front of his attention.

  What was this? In the midst of the even pavement of the cells of the stomach wall lay a funny circular thing, about a twenty-five-hundredth of an inch its diameter was—here was another! But, curse it! It was hot—he stopped looking. . .

  The next day it was the same. Here, in the wall of the stomach of the next to the last mosquito, four days after it had sucked the blood of the unhappy malarious Husein Khan, here were those same circular outlines—clear—much more distinct than the outlines of the cells of the stomach, and in each one of these circles was “a cluster of small granules, black as jet!” Here was another of those fantastic things, and another—he counted twelve in all. He yawned. It was hot. That black pigment looked a lot like the black pigment inside of malaria microbes in the blood of human bodies—but it was hot. Ross yawned, and went home for a nap.

 
And as he awoke—so he says in his memoirs—a thought struck him: “Those circles in the wall of the stomach of the mosquito—those circles with their dots of black pigment, they can't be anything else than the malaria parasite, growing there. . . That black pigment is just like the specks of black pigment in the microbes in the blood of Husein Khan. . . The longer I wait to kill my mosquitoes after they have sucked his blood, the bigger those circles should grow. . . if they are alive, they must grow!”

  Ross fidgeted about—and how he could fidget!—waiting for the next day, that would be the fifth day after his little flock of mosquitoes had fed on Husein under the net. That was the day for the cutting up of the last mosquito of the flock. Came the twenty-first of August. “I killed my last mosquito,” Ronald Ross wrote to Manson, “and rushed at his stomach!”

  Yes! Here they were again, those circle cells, one. . . two. . . six. . . twenty of them. . . They were full of the same jet-black dots. . . Sure enough! They were bigger than the circles in the mosquito of the day before. . . They were really growing! They must be the malaria parasites growing! (Though there was no absolutely necessary reason they must be.) But they must be! Those circles with their black dots in the bellies of three measly mosquitoes now kicked Ronald Ross up to heights of exultation. He must write verses!

  I have found thy secret deeds

  Oh, million-murdering death.

  I know that this little thing

  A million men will save—

  Oh, death, where is thy sting?

  Thy victory, oh, grave?

  At least that is what Ronald Ross, in those memoirs of his, says he wrote on the night of the day of his first little success. But to Manson, telling the finest details about the circles with their jet-black dots, he only said:

  “The hunt is up again. It may be a false scent, but it smells promising.”

  And in a scientific paper, sent off to England to the British Medical Journal, Ronald Ross wrote gravely like any cool searcher. He wrote admitting he had not taken pains to study his brown mosquitoes carefully. He admitted the jet-black dots might not be malaria parasites at all, but only pigment coming from the blood in the mosquito's gullet. There certainly was need for this caution, for he was not sure where his brown mosquitoes came from: some of them might have sneaked in through a hole in the net—and those intruders might have bitten a bird or beast before they fed on his Hindu patient. It was a most mixed-up business. But he could write poems about saving the lives of a million men!

  Such a man was Ronald Ross, mad poet shaking his fist in the face of the malignant Indian sun, celebrating uncertain discoveries with triumphant verses, spreading nets with maybe no holes in them. . . But you must give him this: he had been lifted up. And, as you will see, it was to the everlasting honor of Ronald Ross that he was exalted by this seemingly so piffling experiment. He clawed his way—and this is one of the major humors of human life!—with unskilled but enthusiastic fingers toward the uncovering of a murderous fact and a complicated fact. A fact you would swear it would take the sure intelligence of some god to uncover.

  Then came one of those deplorable interludes. The High Authorities of the Indian Medical Service failed to appreciate him. They sent him off to active duty at doctoring, mere doctoring. Ronald Ross rained telegrams on his Principal Medical Officer. He implored Manson way off there in England. In vain. They packed him off up north, where there were few mosquitoes, where the few he did catch would not bite—it was so cold, where the natives (they were Bhils) were so superstitious and savage they would not let him prick their fingers. All he could do was fish trout and treat cases of itch. How he raved!

  5

  But Patrick Manson did not fail him, and presently Ross came down from the north, to Calcutta, to a good laboratory, to assistants, to mosquitoes, to as many—for that city was a fine malaria pest-hole!—Hindus with malaria crescents in their blood as any searcher could possibly want. He advertised for helpers. An assorted lot of dark-skinned men came, and of these he chose two. The first, Mahomed Bux, Ronald Ross hired because he had the appearance of a scoundrel, and (said Ross) scoundrels are much more likely to be intelligent. The second assistant Ross chose was Purboona. All we know of that man is that he had the booming name of Purboona, and Purboona lost his chance to become immortal because he vamoosed after his first pay day.

  So Ross and Mr. Mahomed Bux set to work to try to find once more the black-dotted circles in the stomachs of mosquitoes. Mr. Mahomed Bux sleuth-footed it about, among the sewers, the drains, the stinking tanks of Calcutta, catching gray mosquitoes and brindled mosquitoes and brown and green dappled-winged ones. They tried all kinds of mosquitoes (within the limits of Ronald Ross's feeble knowledge of the existing kinds). And Mr. Mahomed Bux? He was a howling success. The mosquitoes seemed to like him, they would bite Hindus for this wizard of a Mahomed when Ross could not make them bite at all—Mahomed whispered things to his mosquitoes. . . And a rascal? No. Mr. Mahomed Bux had just one little weakness—he faithfully got thoroughly drunk once a week on Ganja. But the experiments? They turned out as miserably as Mahomed turned out beautifully, and it was easy for Ross to wonder whether the heat was causing him to see things last year at Begumpett.

  Then the God of Gropers came to help Ronald Ross. Birds have malaria. The malaria microbe of birds looks very like the malaria microbe of men. Why not try birds?

  So Mr. Mahomed Bux went forth once more and cunningly snared live sparrows and larks and crows. They put them in cages, on beds, with mosquito bar over the cages, and Mahomed slept, with one eye open, on the floor between the beds to keep away the cats.

  On St. Patrick's day of the year 1898, Ronald Ross let loose ten gray mosquitoes into a cage containing three larks, and the blood of those larks teemed with the germs of malaria. The ten mosquitoes bit those larks, and filled themselves with lark's blood.

  Three days later Ronald Ross could shout: “The microbe of the malaria of birds grows in the wall of the stomach of the gray mosquito—just as the human microbe grew in the wall of the stomach of the brown spot-winged mosquito.”

  Then he wrote to Patrick Manson. This lunatic Ross became for a moment himself a malaria microbe! That night he wrote these strange words to Patrick Manson:

  “I find that I exist constantly in three out of four mosquitoes fed on bird-malaria parasites, and that I increase regularly in size from about a seven-thousandth of an inch after about thirty hours to about one seven-hundredth of an inch after about eighty-five hours. . . I find myself in large numbers in about one out of two mosquitoes fed on two crows with blood parasites. . .”

  He thought he was himself a circle with those jet-black dots. . .

  “What an ass I have been not to follow your advice before and work with birds!” Ross wrote to Manson. Heaven knows what Ronald Ross would have discovered without that persistent Patrick Manson.

  You would think that such a man as Ross, wild as the maddest of hatters, topsy-turvy as the dream of a hasheesh-eater, you would swear, I say, that he could do no accurate experiments. Wrong! For presently he was up to his ears in an experiment Pasteur would have been proud to do.

  Mr. Mahomed Bux brought in three sparrows, and one of these sparrows was perfectly healthy, with no malaria microbes in its blood; the second had a few; but the third sparrow was very sick—his blood swarmed with the black-dotted germs. Ross took these three birds and put each one in a separate cage, mosquito-proof. Then the artful Mahomed took a brood of she-mosquitoes, clean, raised from the grubs, free of all suspicion of malaria. He divided this flock up into three little flocks, he whispered Hindustani words of encouragement to them. Into each cage, with its sparrow, he let loose a flock of these mosquitoes.

  Marvelous! Not a mosquito who sucked the blood of the healthy sparrow showed those dotted circles in her stomach. The insects who had bitten the mildly sick bird had a few. And Ronald Ross, peeping through his lens at the stomachs of the mosquitoes who had bitten the very sick sparrow—found their gull
ets fairly polka-dotted with the jet-black pigmented circles!

  Day after day Ross killed and cut up one after another of the last set of mosquitoes. Day after day, he watched those circles swelling, growing—there was no doubt about it now; they began to look like warts sticking out of the wall of the stomach. And he watched weird things happening in those warts. Little bright colored grains multiplied in them, “like bullets in a bag.” Were these young malaria microbes? Then where did they go from here?

  How did they get into new healthy birds? Did they, indeed, get from mosquitoes into other birds?

  Excitedly Ronald Ross wrote to Patrick Manson: “Well, the theory is proved, the mosquito theory is a fact.” Which of course it wasn't, but that was the way Ronald Ross encouraged himself. There was another regrettable interlude, in which the unseen hand of his incurable restless dissatisfaction took him by the throat, and dragged him away up north to Darjeeling, to the hills that make giant's steps up to the white Himalayas, but of this interlude we shall not speak, for it was lamentable, this restlessness of Ronald Ross, with the final simple experiment fairly yelling to be done. . .

  But by the beginning of June he was back at his birds in Calcutta—it was more than 100 degrees in his laboratory—and he was asking: “Where do the malaria microbes go from the circles that grow into those big warts in the stomach wall of the mosquito?”

  They went, those microbes, to the spit-gland of those mosquitoes!

  Squinting through his lens at a wart on the wall of the stomach of a she-mosquito, seven days after she had made a meal from the blood of a malarious bird, Ronald Ross saw that wart burst open! He saw a great regiment of weird spindle-shaped threads march out of that wart. He watched them swarm through the whole body of that she-mosquito. He pawed around in countless she-mosquitoes who had fed on malarious birds. He watched other circles grow into warts, get ripe, burst, shoot out those spindles. He pried through his lens at the “million things that go to make up a mosquito”—he hadn't the faintest notion what to call most of them—until one day, strangest of acts of malignant nature, he saw those regiments of spindle-threads, which had teemed in the body of the mosquito, march to her spit-gland.