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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!