Microbe Hunters/Chapter 8

It was Theobald Smith who made mankind turn a corner. He was the first, and remains the captain of American microbe hunters. He poked his nose—following the reasoning of some plain farmers—around a sharp turn and came upon amazing things; and now this history tells what Smith saw and what the trail-breakers who came after him found.

"It is in the power of man to make parasitic maladies disappear from the face of the globe!” So promised Pasteur, palsied but famous after his fight with the sicknesses of silkworms. He promised that, you remember, with a kind of enthusiastic vehemence, making folks think they might be rid of plagues by a year after next at the latest. Men began to hope and wait. . . . They cheered as Pasteur invented vaccines—marvelous these were but not what you would call microbe-exterminators. Then Koch came, to astound men by his perilous science of finding the tubercle bacillus, and, though Koch promised little, men remembered Pasteur's prophecy and waited for consumption to vanish. . . . Years went by while Roux and Behring battled bloodily to scotch the poison of diphtheria; mothers crooned hopeful songs into the ears of their children. . . . Some men giggled, but secretly hoped a little too, that the mighty (albeit windy) Metchnikoff might teach his phagocytes to eat up every germ in the world. . . . Diseases were getting a bit milder maybe—the reason is still mysterious—but they seemed in no hurry to vanish, and men had to keep on waiting. . . .

​Then arose a young man, Theobald Smith at the opening of the last ten years of the eighteen hundreds, to show why northern cows get sick and die of Texas fever when they go south, and to explain why southern cows, though healthy, go north and trail along with them a mysterious death for northern cattle. In 1893 Theobald Smith wrote his straight, clear report of the answer to this riddle; there was certainly no public horn-tooting about it and the report is now out of print—but that report gave an idea to the swashbuckling David Bruce; it gave hints to Patrick Manson; it set thoughts flickering through the head of the brilliant but indignant Italian, Grassi; that report gave confidence in his dangerous quest to the American Walter Reed and that gang of officers and gallant privates who refused extra pay for the job of being martyrs to research.

What kind of man is this Theobald Smith (safe to say all but a few thousand Americans have never even heard of him), and how could his discoveries about a cow disease set such dreams stirring—how could those farmer's reasonings that he proved, show microbe hunters a way to begin to realize the poetic promise of Pasteur to men?

In 1884 Theobald Smith was in his middle twenties; he was a Bachelor of Philosophy of Cornell University; he was a doctor of medicine from the Albany Medical College. But he detested the idea of going through life solemnly diagnosing sicknesses he could not hope to cure, offering sympathy where help was needed, trying to heal patients for whom there was no hope—in brief, medicine seemed to him to be a mixed-up, illogical business. He was all for biting into the unknown in places where there was a chance of swallowing it—a little of it—without having mental indigestion. In short, though a physician, he wanted to do science! In especial he was eager—as what searcher was not in those piping days—about mi​crobes. At Cornell (it was before the days of jazz) he had played psalms and Beethoven on the pipe organ; here too (college activities had not yet engulfed mere learning) Theobald Smith dug thoroughly into mathematics, into physical science, into German, and particularly he became enthusiastic about looking through microscopes. Maybe then he saw his first microbe. . . .

But when he came to the medical school at Albany, he found no excitement about possibly dastardly bacilli among the doctors of the faculty; germs had not yet been set up as targets for the healing shots of the medical profession; there was no course in bacteriology there—nor, for that matter, in any medical school in America. But he wanted to do science! And, caring nothing for the healthy drunkennesses and scientific obscenities of the ordinary medical student, Theobald Smith soothed himself with the microscopic study of the interiors of cats. In his first published paper he made certain shrewd observations on peculiar twists of anatomy in the depths of the bellies of cats—that was his bow as a searcher.

He graduated and wanted above everything to be an experimenter, but he had, before anything, to make a living. Just then young American doctors were hurrying to Europe, eager to look over Koch's shoulder to learn ways to paint bacilli, to breed them true, to shoot them under the skins of animals, and to talk like real experts about them. Theobald Smith would have liked to go but he had to find a job. And presently, while those other well-off young Americans were getting in on the ground floor of the new exciting science (afterward they told how they had actually worked in the same room with those great Germans!) and when they were getting ready to land important professorships, Theobald Smith got his job. A humble and surely not academically respectable job it was too! For he was appointed one of the staff of the then feeble, struggling, insignificant, financially rather ill-nourished, and in general almost negligible Bureau of Animal Industry at Washington. Counting Smith, there were four members of the staff ​of this Bureau. The Chief was a good man named Salmon. He was enthusiastically interested in what germs might do to cows and sincerely passionate about the importance of bacilli to pigs—but he knew nothing of how to find the microbes harassing these valuable creatures. Then there was Mr. Kilborne who rejoiced in the degree of Bachelor of Agriculture and was something of a horse doctor (he now runs a hardware store in New York, up-state). And finally, this staff to which Smith came, was glorified by the ancient and redoubtable Alexander, a darky ex-slave who sat about solemnly, and when urged, got up to wash the dirty bottles or chaperon the guinea-pigs.

In a little room lighted by a dormer window under the roof in the attic of a government building, Smith set out to hunt microbes. It was his proper business! Naturally he went at it, as if he had been born with a syringe in his hand and a platinum wire in his mouth. Though a university graduate, he read German well, and of nights, with gulps, he gobbled up the brave doings of Robert Koch; like a young duck taking to the water he began to imitate Koch's subtle ways of nursing and waylaying hideous bacilli and those strange spirilla who swim about like living corkscrews. Template:. . "I owe everything to Robert Koch!" he said, and thought of that far-off genius as some country baseball slugger might think of Babe Ruth.

In his dingy attic he was tireless. It made no difference that he was not strong—all day and part of the night he hunted microbes. And he had musician's fingers that helped him to brew microbe soups with very few spillings. In off moments he would swat the regiments of cockroaches who marched without stopping into his attic from the lumber room close by. In a remarkably short time he had taught himself everything needful and began to make cautious discoveries—he invented a queer new safe kind of vaccine, which contained no bacilli but only their filtered formless protein stuff. The heat of his attic was an intensification of the shimmering hell Washington knows how to be, but he wiped the sweat from the end of his ​nose and set to work in the right, classic way of Koch—with an astounding instinct he avoided the cruder methods of Pasteur.

You talk about freedom of science! You think a free choice to dig in any part of the Unknown is needed by searchers? I used to think so, and I have got into trouble with eminent authorities for saying so—too loudly. Wrong! For Theobald Smith, with little more freedom to start with than some low government clerk—had to research into things Dr. Salmon told him to research at, and Dr. Salmon was paid to direct Smith to solve puzzles which were bothering the farmers and stock-raisers. Such was science in the Bureau of Animal Industry. Dr. Salmon and Bachelor Kilborne and Theobald Smith—to say nothing of the indispensable Alexander—were expected to rush out like firemen and squirt science on the flaming epidemics threatening the pigs and heifers and bulls and rams of the farmers of the land. Just then the stock-raisers were seriously upset by a very weird disease, the Texas fever.

Southern cattlemen bought northern cattle; they were unloaded from their box-cars and put to graze on the fields along with perfectly healthy southern cows; everything would go well for a month or so, and then, bang! an epidemic burst out among northern cows. They stopped eating, they lost dozens of pounds a day, their urine ran strangely red, they stood aimless with arched backs and sad eyes—and in a few days every last one of the fine northern herd lay stiff-legged on the field. The same thing happened when southern steers and heifers were shipped North; they were put into northern fields, grazed there awhile, were driven away perhaps; when northern cows were turned into those fields where their southern sisters had been, in thirty days or so they began to die—in ten days after that a whole fine herd might be under the ground.

​What was this strange death, brought from the South by cattle never sick with it themselves, and left invisibly in ambush on the fields? Why did it take more than a month for those fields to become dangerous? Why were they only dangerous in the hot summer months?

The whole country was excited about it; there was bad feeling between the meridional cowmen and their colleagues of the North; New York City went into a panic when carloads of stock shipped East for beef began to die in hundreds on the trains. Something must be done! And the distinguished doctors of the Metropolitan Health Board went to work to try to find the microbe cause of the disease. . . .

Meanwhile certain wise old Western cattle growers had a theory—it was just what you would call a plain hunch got from smoking their pipes over disastrous losses of cows—they had a notion that Texas fever was caused by an insect living on the cattle and sucking blood; this bug they called a tick.

The learned doctors of the Metropolitan Board and all of the distinguished horse doctors of the various state Experiment Stations laughed. Ticks cause disease! Any insect cause disease! It was unheard of. It was against all science. It was silly! ". . . A little thought should have satisfied any one of the absurdity of this idea," pronounced the noted authority, Gamgee. This man was up to his nose in the study of Texas fever, and never mentioned a tick; the scientists all over gravely cut up the carcasses of cows and discovered bacilli there (but never saw a tick). "It is the dung spreads it!" said one. "You are wrong, it is the saliva!" said another. There were as many theories as there were scientists. And the cattle kept on dying.

Then, in 1888, Dr. Salmon put Theobald Smith, with Kilborne to help him, and Alexander to clean up after them—saying nothing about ticks Salmon put his entire staff to work ​on Texas fever. "Discover the germ!" he told Smith. That year they had nothing but the spleens and livers of four dead Texas fever cows to investigate; packed in pails of ice, from Virginia and Maryland to his furnace-like attic came those livers and spleens. Theobald Smith had what so many of those mystified scientists and baffled horse doctors lacked—horse sense. He turned his microscope on to different bits of the first sample of spleen; he spied microbes in it; there was a veritable menagerie of different species of them.

Then Smith sniffed at that bit of spleen. He wrinkled up his nose—it smelled. It was spoiled.

At once he sent out messages, asking the stockmen to get the insides out of their cattle right away after they died, to pack them quickly in ice, to see they got to the laboratory more quickly. It was done, and in the next spleen he found no microbes at all—but only a great quantity of mysteriously broken up red corpuscles of the blood. "They look wrecked!" he said. But he could find no microbes. He was still young, and sarcastic, and impatient with any searcher who couldn't do close hard thinking. A man named Billings had claimed a foolish common bacillus (which he found in every part of every dead cow and in every corner of the barnyard—including the manure pile—as well) was the cause of Texas fever. Billings wrote a spread-eagle paper, saying: "The sun of original research, in disease, seems to be rising in the West instead of the East!"

"Somewhat pompous claims," said Smith, and he blew away all that pseudo-scientific rubbish in a few dry sentences. Smith knew it was no good sitting in a laboratory, with no matter how many guinea-pigs and what an array of fine syringes, simply to peer at the spleens and livers of more or less odoriferous cows. He was an experimenter; he must study the living disease; be there while the cows kicked their last quivering spasms; he must follow nature. He began to get ready for the summer of 1889, when, one day, Kilborne told him of the cattlemen's ridiculous theory about the ticks.

​In a moment he pricked up his mental ears. "The farmers, the ones who lose the stock, who see most of Texas fever, they think that?"

Now, though Theobald Smith was born in a city, he liked the smell of hay just cut and the brown furrows of fresh-turned fields. There was something sage—something as near as you can come to truth for him in a farmer's clipped sentences about the crops or the weather. Smith was learned in the marvelous shorthand of mathematics; men of the soil don't know that stuff. He was absolutely at home among the scopes and tubes and charts of shining laboratories—in short, this young searcher was full of sophisticated wisdom that laughs at common sayings, that often jeers at peasant platitudes. But in spite of all of his learning (and this was an arbitrary strange thing about him!) Theobald Smith did not confuse fine buildings and complicated apparatus with clear thinking—he seemed always to be distrusting what he got out of books or what he saw in tubes. . . . He felt the dumbest yokel to be profoundly right when that fellow took his corn-cob pipe from his maybe unbrushed teeth to growl that April showers brought May flowers.

He listened to Kilborne's gossip about that idiotic theory of ticks; Kilborne told him the cattlemen of the West were pretty well agreed it was ticks. Well, pondered Smith, those fellows were surely innocent of any fancy reasoning to corrupt their brains, they reeked of the smell of steers and heifers, they were almost, you might say, a part of their animals; and they were the ones who had to lay awake nights knowing this dreadful disease was turning their cattle's blood to water, to taking the bread from their children's mouths. They had to bury those poor wasted beasts. And these experienced farmers one and all said: "No ticks—no Texas fever!"

Theobald Smith would follow the farmers. He would watch the disease as nearly as possible as those stockmen had watched it. Here was a new kind of microbe hunting—following nature, and changing her by just the smallest tricks. . . . The sum​mer of 1889 came, the days grew hot; the year before the cattlemen had complained bitterly about their losses. It was urgent to do something, even the government saw that. The Department of Agriculture loosened up with a good appropriation, and Dr. Salmon, the Director, directed that the work begin—luckily he knew so little about experiments that his direction never bothered Smith in the slightest.

With Kilborne, Theobald Smith now built an outlandish laboratory, not between four walls but under the hot sky, and the rooms of that place of science were nothing more than five or six little dusty fenced off fields. On June 27 of 1889, seven rather thin but perfectly healthy cows came off a little boat which brought them from farms in North Carolina, from the heart of the Texas fever country, where it was death for northern cattle to go. And these seven cows were, one and all of them, decorated, infested and plagued by several thousands of ticks, assorted sizes of them, some so tiny they needed a magnifying glass to be seen—and then there were splendid female ticks half an inch long, puffed up with blood sucked from their long-suffering hosts.

Into securely fenced Field No. 1, Smith and Kilborne drove four of these tick-loaded southern cattle, and with them they put six healthy northern beasts— "Pretty soon the northerners will be getting the ticks on them too, they have never been near Texas fever. . . . They are susceptible, and then. . . ?" said Smith. "And now for a little trick to see if it is the ticks we have to blame!"

So Theobald Smith did his first little trick—call it an experiment if you wish—it was a stunt a shrewd cattleman might have thought of if he hadn't been too busy to try it; it was an experiment all other American scientists considered it silly to attempt. Smith and Kilborne set out to pick off, with their hands, every single tick from the remaining three southern ​cattle! The beasts kicked and switched their tails in these strange experimenters' faces; it was way over a hundred in the sun, and the dust from the rampaging of the offended cows hung in clouds around them and stuck to their sweaty foreheads. Buried away under the matted hair of the cattle hid those ticks, and the little ones out in the open seemed to crawl away under the hair when the cramped fingers of the searchers went after them. And how those damned parasites stuck to their cow-hosts—there were magnificent blood-gorged lady ticks who mashed up into nasty messes when you tried to pull them off—it was a miserable business!

But toward evening of that day they could find never a tick on any of those three North Carolina cows, and into Field No. 2 they put them, along with four healthy northern beasts. "These northerners, perfectly fit for a fatal attack of Texas fever, will be rubbing noses with the southerners, will be nibbling the same grass, drinking from the same water, sniffing at the North Carolina cow's excretions—but they'll get no ticks from them. Well—now to wait and see if it's the ticks who are to blame!"

July and the first of August were two months of hot but strenuous waiting. Smith, with a Government bug-expert named Cooper Curtice, kept himself busy with vast studies of the lives and works and ways of ticks. They discovered how a six-legged baby tick climbs up onto a cow, how it fastens itself to the cow's hide, begins to suck blood, sheds its skin, proudly acquires two more legs, sheds its skin again; they found out the eight-legged females then marry (on the cow's back) each of them a little male, how the lady-ticks then have great feasts of blood, grow to tick womanhood—and at last drop off the cow to the ground to lay their two thousand or more eggs; so, hardly more than twenty days after their journey up the leg of the cow, their mission in life is done, and they shrivel up and die—while strange doings begin in each of those two thousand eggs. . . .

Meanwhile, every day—it was a relief to get out of that ​cockroachy attic even to those burning fields—Theobald Smith journeyed out to his open air laboratory where Kilborne the future hardware dealer was in command. He went to Field No. 1 to see if ticks had got on to any of the northern cattle yet, to see if they were getting hot, if their heads drooped; he crossed over to Field No. 2 to pick a few more ticks off those three North Carolina cows—a few new ones always seemed to be popping up, grown from ones too small to see that first day!—it was nervous business, making sure those three cows stayed clean of ticks. . . . It was, to tell the truth, a perspiring and not too interesting waiting until that day a little past the middle of August, when the first northern cow began to show ticks, and presently to stand with her back arched, refusing to eat. Then the ticks appeared on all the northerners; they burned with fever, their blood turned to water, their ribs stuck out and their flanks grew bony—and ticks? They seemed to be alive with ticks!

But on Field No. 2, where there were no ticks, the northern cows stayed as healthy as their North Carolina mates. . . .

Each day the fever of the northern beasts in Field No. 1 went higher—then one by one they died; the barns ran red with the blood of the post mortems, and there were rushings to and fro between the dead beasts on the field and the microscopes in the attic—even Alexander, dimly sensing the momentous things afoot, even Alexander got busy. And Theobald Smith looked at the thin blood of the dead cows. "It is the blood the unknown Texas fever microbe attacks—something seems to get into the blood corpuscles of the cows and burst them open—it is inside the blood cells I must look for the germ," pondered Smith. Now, though he distrusted the reports of alleged microscope experts, he was nevertheless himself mighty sharp with this machine. He turned his most powerful lens onto the blood of the first cow that died, and—here was luck!—in the very first specimen he spied queer little punched-out pear-shaped spaces in the otherwise solid discs of the blood corpuscles. At first they simply looked like holes, ​but he focussed up and down, and fussed, and looked at a dozen thin bits of glass with blood between them. Presently these spaces began to turn into queer pear-shaped living creatures for him. In the blood of every beast dead of Texas fever he found them—always inside the corpuscles, wrecking the corpuscles, turning the blood to water. Never did he find them in the blood of a healthy northern cow. . . . "It may be the microbe of Texas fever," he whispered, but like a good peasant he did not jump to conclusions—he must look at the blood of a hundred cows, sick and healthy, he must examine millions of red blood cells to be sure. . . .

By now the hottest weather had passed, it was September, and in Field No. 2, the northern cattle, all four of them, kept on grazing and grew fat—there were no ticks there. And Smith muttered: "We'll see if it's the ticks who are to blame!" and he took two of these unharmed northern beasts and led them into Field No. 1, where so many beasts had died—in a week a few of the little red-brown bugs were crawling up these new cow's legs. In a little more than two weeks one of these cows was dead, and the other sick, of Texas fever.

But there never was a man who needed more experiences to convince him of something he wanted to believe. He must be sure! And there was still another simple trick he could try—call it an experiment if you wish. From North Carolina, from the fatal fields down there, came large cans and these cans were filled with grass, that swarmed with ticks, crawling, thirsty for the blood of cows. These cans Theobald Smith took on to Field No. 3, where no southern cattle or their blood-sucking parasites had ever been, and he plodded up and down this field, and all over it he sowed his maybe fatal seed—of ticks. Then four northern cattle were led by Kilborne on to this field—and in a few weeks their blood ran thin, and one died, and two of the remaining three had severe bouts of Texas fever but recovered.

So, first of all microbe hunters, Theobald Smith traced out the exact path by which a sub-visible assassin goes from one animal to another. In the field where there were southern cattle and ticks, the northern cattle died of Texas fever; in the field where there were southern cattle without ticks the northern cows grew fat and remained happy; in the field where there were no southern cattle but only ticks—there too, the northern cattle came down with Texas fever. It must be the tick. By such simple, two-plus-two-make-four—but oh! what endlessly careful experiments, Theobald Smith proved those western cowmen to have observed a great new fact of nature. . . . He chiseled that fact out of folk-shrewdness, just as the anonymous invention of the wheel has been taken out of folk-inventiveness and put to the uses of modern whirring dynamos. . . .

You would think he thought he had proved enough—those experiments were so clear. You would think he would have advised the government to start an exterminating war on ticks, but that was not the kind of searcher Theobald Smith was. Instead, he waited for the heat of the summer of 1890 to come, and then he started doing the same experiments over, and some new ones too, all of them simple tricks, but each of them necessary to nail down the fact that the tick was the real criminal. "How do those bugs carry the disease from a southern cow to a northern one?" he pondered. "We know now one tick lives its whole life on just one cow—it doesn't flit from beast to beast like a fly. . . ." This was a knotty question—too subtle for the crude science of the ranchers—and Smith set himself to chew that knot. . . .

"It must be," he meditated, "that ticks, when they have sucked enough blood, and are ripe, drop off, and are crushed, and leave the little pear-shaped microbes on the grass—to be eaten by the northern cattle!"

So he took thousands of ticks, sent up in those cans from ​North Carolina, and mixed them with hay, and fed them to a susceptible northern cow kept carefully in a special stable. But nothing happened; the cow seemed to relish her new food, she got fat. He tried drenching another cow with mashed up ticks made into a soup—but that cow too seemed to enjoy her strange dose. She prospered on it.

It was no go—cows didn't, apparently, get the microbe by eating ticks; he was mixed up for a while. And other plaguey questions kept him awake nights. Why was it that it took thirty days or more, after the southern tick-loaded cows came on the field, for such a field to become dangerous? Stockmen knew this too; they knew they could mix just-arrived southern cows with northern ones, and keep them together twenty days or so, and then if they took the northern ones away—they would never get Texas fever; but if you left them in that field a little longer (even if the southern cows were taken away) bang! would come the fatal epidemic into the herd of northerners. That was a poser!

Then one day in this summer of 1890, by the most strange, the most completely unforeseen of accidents, every jagged piece of the puzzle fell into its proper place. The solution of the riddle fairly clubbed Theobald Smith; it yelled at him; it forced itself on him while he was busy doing other things. He was at all kinds of experiments just then; he was bleeding northern cows for gallons of blood to give them an anemia—to make sure those funny little pear-shaped objects he had found in the corpuscles of Texas fever cattle were microbes, and not simply little changes in blood that might come from anemia. He was learning to hatch nice clean young ticks artificially in glass dishes in his laboratory; he was still laboriously picking ticks off southern cows—and sometimes he failed to get them all off and the experiments went wrong—to prove that tickless southern cows are harmless to northern ones; he was discovering the strange fact that northern calves get only a mild fever on a field fatal to their mothers. He fussed about ​finding every single effect a tick might have on a northern cow—it might do other damages besides giving her Texas fever . . . ?

Then came that happy accident. He asked himself: "If I should put good clean young ticks, hatched in glass dishes in my attic, ticks who never have been on cattle or on a dangerous field—if I should put such ticks on a northern cow and let them suck their fill of her blood—could those ticks take out enough blood to give the cow an anemia?" It seems to me to have been an aimless question. His thoughts were a thousand miles away from Texas fever. . . .

But he tried it. He took a good fat yearling heifer, put her in a box-stall, and day after day put hundreds of clean baby ticks on her, holding her while these varmints crawled away beneath her hair to get a good grip on her hide. Then day after day, while the ticks made their meals, he cut little gashes in her skin to get a drop of blood to see if she was becoming anemic. And one morning Theobald Smith came into her stall—for the usual routine—he put his hand on that heifer. . . . What was this? She felt hot! Very hot! Suspiciously too hot! She drooped her head, and would not eat—and her blood which before had welled out from the gashes thick and rich and red—that blood ran very thin and darkish. He hurried back to his attic with samples of the blood between little pieces of glass. . . . Under the microscope it went, and sure enough!—here were twisted, jagged, wrecked blood corpuscles instead of good even round ones with edges smooth as a worn dime. And inside these broken cells—it was fantastical, this business!—were the little pear-shaped microbes. . . . Here was the fact, stranger than any pipe-dream—for these microbes must have come up from North Carolina on old ticks, had gone out of the old ticks into the eggs they had laid in the glass dishes, they had survived in the baby ticks hatched out these eggs—and these babies had at last shot them back, ready to kill, into their destined but completely accidental victim, that yearling heifer!

​In a flash all those mysterious questions cleared up for Theo- bald Smith.

It was not the old, blood-stuffed tick but its child, the baby tick, who sneaked the assassin into the northern cows; it was this little five- or ten-day-old bug who carried the murderer.

Now he saw why it was that fields took so long to become dangerous—the mother ticks have to drop off the southern cattle; it takes them some days to lay their eggs; these eggs take twenty days or more to hatch; the tick babies have to scamper about to find a cow's leg to crawl up on—all that takes many days, weeks. Never was there a simpler answer to a problem which, without this strange chance, might not yet be solved. . . .

So soon as he could hatch out other thousands of ticks in warm glass dishes, Theobald Smith proceeded to confirm his marvelous discovery; he proved it clean. For every northern cow, on whom he stuck his regiments of incubator ticks, came down with Texas fever. But he was a glutton for proofs, as you have seen, and when the summer of 1890 waned and it grew cold, he installed a coal-stove in a stable, hatched the ticks in a heated place, put a cow in the hot stable, stuck the little ticks diligently onto the hide of the cow, the stove instead of the sun made them grow as they should—and the cow got Texas fever in the winter, a thing which never happens in nature!

For two more summers Smith and Kilborne tramped about their fields, caulking up every seam in the ship of their research, answering every argument, devising astounding simple but admirably adequate answers to every objection the savant horse doctors might make—before these critics ever had a chance to make objections. They found strange facts about immunity. They saw northern calves get mild attacks of Texas fever, a couple of attacks in one summer maybe, and then next year, more or less grown up, graze unconcerned on fields absolutely murderous to a non-immune northern cow. . . . So they explained why southern cattle never die of ​Texas fever. This fell disease is everywhere that ticks are in the South—and ticks are everywhere; ticks are biting southern cattle and shooting the fatal queer pears into them all the time; these cattle carry the microbes about with them in their blood—but it doesn't matter, for the little sickness in their calfhood has made them immune.

Finally, after four of these stifling but triumphant summers, Theobald Smith sat down, in 1893, to answer all the perplexing questions about Texas fever—and to tell how the disease can be absolutely wiped out (just then the ancient Pasteur who had prophesied that about all disease was getting ready to die). Never—and I do not forget the masterpieces of Leeuwenhoek or Koch or any genius in the line of microbe hunters—never, I say, has there been written a more simple but at the same time more solid answer to an enigma of nature. A bright boy could understand it; Isaac Newton would have taken off his hat to it. He loved Beethoven, did young Smith, and for me this "Investigation into the Nature, Causation, and Prevention of Texas or Southern Cattle Fever" has the quality of that Eighth Symphony of Beethoven's sour later years. Absurdly simple in their themes they both are, but unearthly varied and complete in the working out of those themes—just as nature is at once simple and infinitely complex. . . .

And so, with this report, Theobald Smith made mankind turn a corner, showed men an entirely new and fantastic way a disease may be carried—by an insect. And only by that insect. Wipe out that insect, dip all of your cattle to kill all their ticks, keep your northern cattle in fields where there are no ticks, and Texas fever will disappear from the earth. To-day whole states are dipping their cattle and to-day Texas fever which once threatened the great myriads of American cattle is no longer a matter for concern. But that is only the beginning of the beneficent deeds of this plain report, this ​classic unappreciated and completely out of print. For presently, on the veldt and in the dangerous bush of southern Africa, a burly Scotch surgeon-major swore at the bite of a tsetse fly—and wondered what else besides merely annoying one, these tsetse flies might do. And a little later in India, and at the same time in Italy, an Englishman and an Italian listened to the whining song of swarms of mosquitoes, and dreamed and wondered and planned strange experiments—

But those are the stories the next chapters will celebrate. They tell of ancient plagues now in reach of mankind's complete control—they tell of a deadly yellow disease now almost entirely abolished. They tell of men projecting pictures of swarming human life and turreted cities of the future reaching up and up, built on jungles now fit only for man-killing wild beasts and lizards. It was this now nearly forgotten microbe hunting of Theobald Smith that first gave men the right to have visions of a world transformed.