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“Sorry to keep you waiting,” I apologized to Roger. “I just thought . . .” I reached into the cupboard, withdrew three small earthenware pots, and uncorked them.
“Not a problem,” he assured me. He watched with fascination as I checked each slide to be sure the blood-smear was dry, then slid a bit of glass into each of the pots.
“All right, then.” Now I could turn my attention to cleaning and dressing his hand—a straightforward-enough process. “Not so bad as I thought,” I murmured, wiping caked blood off his knuckles. “It bled quite a bit, which is good.”
“Aye, if you say so.” He didn’t flinch at all, but carefully kept his face turned away from what I was doing, his attention focused out the window.
“Washes out the wounds,” I explained, dabbing with alcohol. “I needn’t swab so deeply to clean them.”
He drew in his breath with a sharp hiss, then, to distract himself, nodded at the pots where the slides were soaking.
“Speaking of blood, what are you doing with Mistress Mousie’s?”
“Trying something. I don’t know whether it will work or not, but I’ve made up some experimental stains, using extracts from some of the dyeing-plants. If any of them work on blood, I’ll be able to see the red cells clearly under the microscope—and what’s in them.” I spoke with a mixture of hope and tentative excitement.
Trying to duplicate cellular stains with the materials I had at hand was a long shot—but not totally unfeasible. I had the ordinary solvents—alcohol, water, turpentine and its distillates—and I had a great range of plant pigments to try, from indigo to rosehips, along with a good working knowledge of their dyeing properties.
I hadn’t any crystal violet or carbofuchsin, but I had been able to produce a reddish stain that made epithelial cells highly visible, if only temporarily. It remained to be seen whether the same stain would work on red blood cells and their inclusions, or whether I should need to try differential staining.
“What is in them?” Roger turned to look at me, interested.
“Plasmodium vivax,” I said. “The protozoan that causes malaria.”
“You can see it? I thought germs were much too small to see, even under a microscope!”
“You’re as bad as Jamie,” I said tolerantly. “Though I do love to hear a Scotsman say ‘gerrrms.’ Such a sinister word, spoken in a deep voice with that rolling ‘r,’ you know.”
Roger laughed. The hanging had destroyed much of the power of his voice, but the lower, harsher registers remained.
“Nearly as good as murrrrderr,” he said, rumbling like a cement mixer.
“Oh, nothing’s as good as ‘murrrderr’ to a Scot,” I assured him. “Bloody-minded blokes that you all are.”
“What, all of us?” He grinned, plainly not minding this gross generalization in the least.
“To a man,” I assured him. “Mild enough to look at, but insult a Scot or trouble his family, and it’s up wi’ the bonnets of bonnie Dundee. All the blue bonnets are over the border, and next thing you know, it’s lances and swords all over the Haughs of Cromdale.”
“Remarkable,” he murmured, eyeing me. “And you’ve been married to one for . . .”
“Quite long enough.” I finished my sponging and rinsing and blotted the back of his hand, small red patches soaking into the fresh gauze. “Speaking of bloody men,” I added casually, “do you happen to know your own blood type?”
One dark brow went up at that. Well, I didn’t mean to slip it by him, after all; I’d only wanted a way to broach the question.
“Yes,” he said slowly, “I do. It’s O-positive.”
The dark green eyes were fixed on mine, steady with interest.
“Very interesting,” I said. I replaced the gauze square with a fresh one, and started winding a bandage around it.
“Just how interesting is it?” he asked. I glanced at him, and met his eyes.
“Moderately.” I drew out the slides, dripping pink and blue dyes. One slide I propped against the milk jug to dry, the other two I exchanged, putting the pink slide into the blue stain, and vice-versa.
“There are three main blood groups,” I said, blowing gently on the propped-up slide. “More really, but those three are the ones everyone knows about. It’s called the ABO grouping, and everyone is said to have type A, type B, or type O blood. The thing is, like all your other traits, it’s determined genetically, and—human beings being heterosexual, generally speaking—you have one half your genes for any trait from one parent, the other half from the other.”
“I dimly recall that bit from school,” Roger said dryly. “All those bloody charts—excuse me—about hemophilia in the Royal Family, and the like. I assume it has a certain amount of personal significance now, though?”
“I don’t know,” I said. “It might have.” The pink slide looked dry; I laid it gently on the stage of the microscope and bent to adjust the mirror.
“The thing is,” I said, squinting through the eyepiece as I twiddled the focusing knob, “those blood groups are to do with antibodies—little odd-shaped things on the surfaces of blood cells. That is, people who are type A have one sort of antibody on their cells, people with type B have a different sort, and people with type O don’t have any at all.”
The red blood cells showed up suddenly, faintly stained, like round pink ghosts. Here and there a blotch of darker pink indicated what might be a bit of cellular debris, or perhaps one of the larger white blood cells. Not much else, though.
“So,” I went on, lifting the other two slides from their baths, “if one of his parents gave a child the gene for type O blood, and the other gave him one for type A, the child’s blood will show up as type A, because it’s the antibodies that are tested for. The child does still have the gene for type O, though.”
I waved one of the slides gently in the air, drying it.
“My blood type is A. Now, I happen to know that my father’s blood was type O. In order to show up with type O blood, that means that both his genes must have been for O. So whichever of those genes he gave me, it has to have been for O. The A gene therefore came from my mother.”
Seeing a familiar glaze come over his features, I sighed and set the slide down. Bree had been drawing pictures of penicillin spores for me, and had left her pad and graphite pencil by the microscope. I took it and flipped to a fresh page.
“Look,” I said, and drew a quick chart.
“Do you see?” I pointed with the stick of graphite. “I don’t know my mother’s type for sure, but it doesn’t matter; for me to have type A blood, she must have given me her gene for it, because my father hadn’t one.”
The next slide was nearly dry; I laid down the pencil, put the slide in place, and bent to look through the eyepiece.
“Can you see blood types—these antibodies—through a microscope?” Roger was quite close behind me.
“No,” I said, not looking up. “The resolution’s nowhere near good enough. But you can see other things—I hope.” I moved the knob a fraction of an inch, and the cells sprang into focus. I let out the breath I had been holding, and a small thrill went through me. There they were; the disc-shaped pinkish blobs of the red blood cells—and here and there, inside a few of the cells, a darkish blob, some rounded, some looking like miniature nine-pins. My heart thumped with excitement, and I made a small exclamation of delight.
“Come look,” I said, and stood aside. Roger bent, looking quizzical.
“What am I looking at?” he asked, squinting.
“Plasmodium vivax,” I said proudly. “Malaria. The small dark blobs inside the cells.” The rounded blobs were the protozoans, the single-celled creatures transferred to the blood in a mosquito’s bite. The few that looked like bowling pins—those were protozoa in the act of budding, getting ready to reproduce themselves.
“When they bud,” I explained, bending for another look myself, “they multiply until they burst the blood cell, and then they move into new blood cells, multiply, and burst those, too—that’s when the patient suffers a malarial attack, with the fever and chills. When the Plasmodium are dormant—not multiplying—the patient is all right.”
“And what makes them multiply?” Roger was fascinated.
“No one knows, exactly.” I drew a deep breath, and corked up my bottles of stain again. “But you can check, to see what’s happening, if they are multiplying. No one can live on quinine, or even take it for a long period—Jesuit bark is too expensive, and I don’t know what the long-term effects on the body might be. And you can’t touch most protozoans with penicillin, unfortunately.
“But I’ll check Lizzie’s blood every few days; if I see the Plasmodium increasing sharply, then I’ll start giving her the quinine at once. With luck, that might prevent an outbreak. Worth a try, certainly.”
He nodded, looking at the microscope and the pink-and-blue-splotched slide.
“Well worth it,” he said quietly.
He watched me move about, tidying up the small debris of my operations. As I bent to retrieve the bloody cloth in which he’d wrapped his hand, he asked, “And you know Bree’s blood type, of course?”
“Type B,” I said, eyes on the box of bandages. “Quite rare, particularly for a white person. You see it mostly in small, rather isolated populations—some Indian tribes in the American Southwest, certain black populations; probably they came from a specific area of Africa, but of course by the time blood groups were discovered, that connection had been long lost.”
“Small, isolated populations. Scottish Highlanders, perhaps?”
I lifted my eyes.
“Perhaps.”
He nodded silently, clearly thinking to himself. Then he picked up the pencil, and slowly drew a small chart of his own on the pad.
“That’s right,” I said, nodding as he looked up at me in question. “Exactly right.”
He gave me a small, wry smile in response, then dropped his eyes, studying the charts.
“Can you tell, then?” he asked finally, not looking up. “For sure?”
“No,” I said, and dropped the cloth into the laundry basket with a small sigh. “Or rather—I can’t tell for sure whether Jemmy is yours. I might be able to tell for sure if he’s not.”
The flush had faded from his skin.
“How’s that?”
“Bree is type B, but I’m type A. That means she’ll have a gene for B and my gene for O, either of which she might have given Jemmy. You could only have given him a gene for type O, because that’s all you have.”
I nodded at a small rack of tubes near the window, the serum in them glowing brownish-gold in the late afternoon sun.
“So. If Bree gave him an O gene, and you—his father—gave him an O gene, he’d show up as type O—his blood won’t have any antibodies, and won’t react with serum from my blood or from Jamie’s or Bree’s. If Bree gave him her B gene, and you gave him an O, he’d show up as type B—his blood would react with my serum, but not Bree’s. In either case, you might be the father—but so might anyone with type-O blood. IF, however—”