"Bad doggie," I said, with feeling. "Bad!" He startled: his ears wilted, his sandy tail melded to his white belly, and he skulked into the kitchen, where, darting at me looks of shock and awe, he trotted into the gap between the sink and the stove, as far as his shoulders, and drooped his head against the wall. He huddled there, rib cage pumping, panting and yawning with stress. A whiff of dog sweat filled the air. What had I done?

What happened next was predictable. I spent the rest of the evening cooking for a dog. I spent the rest of the year training my new dog. I named him Wolf, for wolfing my snacks. And I discovered that he was invisible.

MY DISCOVERY BEGAN when the postal carrier slid out of her car with a packet in hand, and walked straight into a dog sniffing her sneakers. As I opened my mouth to call him, she stepped forward, and kept stepping, exactly where Wolf was not. I stared openmouthed, missing my cue about the nice sunshine we were having.

"I'm so sorry, he isn't trained yet," I said. She looked puzzled. "The dog," I added. "He's new."

"You got a dog? I'm glad he's not out, I hate it when dogs get out." She smiled, getting back into the car as Wolf tried to goose her.

Then Mike, of Mike's Racc.o.o.n Wranglers, came to install shields in my chimney. Wolf trotted out, tongue shaking like a long jelly, straight toward the braced, separated knees of an unsuspecting Mike, who surveyed my roof . . . and sidestepped, boots suddenly nimble. He unfolded his ladder with the motions, if not the conversation, of a workman avoiding a large dog.

"Sorry about the dog," I said. Mike looked puzzled. "See the dog?" I asked. Still holding the ladder, with a slightly defensive air, Mike looked all around me. "Oh! Never mind," I apologized rapidly, "I thought I saw-the neighbor's dog out there, in the yard, but it was only-oh! Never mind, I must have seen the woodchuck." Mike laughed and climbed the ladder. All the while, Wolf stood leaning on my legs, panting with pleasure. Conclusions framed themselves. But I knew invisible animals, and I knew people, and this was not the proper behavior of people around invisible animals. They should not be avoiding what they could not see.

ALL MY LIFE I HAD KNOWN that there were plenty of invisible dogs around; now I faced the surprising fact that I'd never thought seriously about them. I had known that among the unleashed dogs pa.s.sing me in the street, sniffing behind bushes, or posting liquid messages on trees, a goodly number were not visible to normal humans-but somehow, this had never provoked either wonder, or basic questions. I hadn't paid attention! Perhaps the fault lay with my childhood bedtime stories, which were often about an invisible poodle named Tidbit, who had shyly but persistently dogged Granduncle Erasmus on his extensive travels through Europe, Africa, and what he'd called "the Orient." At the bottom of my mind, all invisible dogs were Tidbit, whom I had outgrown, and about whom I had no more questions than I did about swing sets. Shame on me, because the basic questions were burning ones-and Granduncle Erasmus was no longer here to answer them.

Fortunately, a rich cousin of mine (who wishes to remain anonymous) funds and administers a private archive of my family's records. I visited this chilled, silent repository, and delved deeply into the papers of the invisible-beast spotters who had preceded me in our genealogy. I read till my eyes watered, taking notes. The papers went back centuries; the oldest ones, too fragile for handling, had to be viewed online. Not one of those diaries, legal doc.u.ments, scholarly articles, newspapers, handbills, sc.r.a.pbooks, broadsides, or letters (the most plentiful item) explained why people avoided a dog they could not see. On the other hand, I gathered a good deal of interesting information, and was able to piece together a partial portrait of invisible dogs; I call them Invies, for short.

The most suggestive item was that Invies seemed to arrive in normal litters; I found no mention of their breeding true. A recessive trait, perhaps? Equal in interest was the fact that they were scavengers, lurking around dumps and households, in a gray area between wildness and domesticity. And they were quite timid. An Elizabethan ancestor-an irascible barber-surgeon who'd lived with a pack of invisible sheepdogs-described them succinctly as Cringeing Curs, tho Artful and eke Thievish. On rare occasions, Invies had formed attachments to my family's invisible-beast spotters. Tidbit, for instance, would not allow herself to be petted, yet had followed my granduncle around the world. Likewise, a nineteenth-century ancestress-an Ohio schoolmistress who had written a prizewinning monograph on edible cattails-had lived on warm terms with an Invie collie named Hecuba. Recording her cattail honors, this lady wrote in her diary, Hecuba being so very spoilt, I cannot but reflect how easy a thing it is for that much nearer invisible companion, my Soul, to be as spoilt by worldly Vanities. Helpfully, this diary also described Hecuba's behavior in the litter where she'd been discovered. The details accorded with other hints about the puppyhood of Invies. They were, in the canine social hierarchy, lower than the lowest-virtual outcasts, not a.s.sertive at all: if their littermates merely inhaled with the intention of growling, the little Invies rolled over and piddled on themselves. In adult life, Invies' groveling status and habits gave them advantages. My granduncle had seen Tidbit s.n.a.t.c.h sc.r.a.ps from under the nose of a bullmastiff, who had given her a glare instead of a shredded ear. These instances, I noted, must mean that visible animals could see invisible dogs-an idea that violated one of my first principles, namely, that only invisible animals could see other invisible animals. An exception to this rule was hard to credit. Yet, if I accepted the anecdotes, it seemed that an Invie's subsocial status canceled dogs' usual responses, giving it a few precious, life-preserving privileges, similar to the position of the fool in a medieval court. And like fools, Invies were highly intelligent; it went with the territory.

I LEARNED MUCH FROM the archives, but not what I came for. Why did people avoid a dog that they could not see? The question remained unanswered. A last-resort possibility was, simply, that Wolf wasn't invisible. After all, I reasoned, a postal carrier and a racc.o.o.n wrangler were not a reliable sample. To test Wolf's invisibility, I should bring him out in public, among lots of random people. I put on a dress with long drippy sleeves, slipped a tote bag over my arm, and secured Wolf by a leash tucked behind my sleeves and the bag. Thus attired, I went with my dog to the hairdresser.

n.o.body noticed at first. The lavender-haired sylphs behind the register greeted me with their usual sweetness. The businesswomen sipped their imported water with lemon slices, imperturbably, at the bar. The old wives who had almost stopped caring, who were here for an hour's vacation, maternally told their stylists that their hair looked very nice. A row of plastic-draped ladies being shampooed in dark marble sinks, their bare feet elevated on chair rests, did not so much as twitch their freshly lacquered toes when those toes exerted a strong fascination on Wolf, whom I had to drag back by his camouflaged leash. n.o.body looked twice. My hairdresser, pinning a cape around my neck as I nestled in her padded chair-with Wolf huddled under her counter, violently sneezing-proceeded to step over his paws, and, as he grew bolder, to dodge his slinking forays around her cart. When he retired again underneath the counter, he a.s.sumed such obscurity, such utter unnoticedness, that I almost forgot he was there. My point was proved, I thought.

Then someone saw him.

The witness lay on a settee by the manicurist's station, to the right of my chair. It was a turquoise suede coat. Abruptly, one of its sleeves jerked forward, while the rest of the coat slewed helplessly, flashing its satin lining.

"No, no!" shouted the coat's owner, her nails still spread before the eyebrow-hiked manicurist. "Fluffy! Bad girl!" The sleeve, with earsplitting cries, extruded part of a Bichon Frise, a sort of bubble bath with a nose, who pumped her lamblike forelegs up and down with great vigor, prevented from shooting forth by a sparkly collar. "What's gotten into her-I'm so sorry," gasped her owner, untying a turquoise leash, "I'll take her to the car-excuse me-"

Everyone stared at Fluffy, carried off in frothing disgrace. No one looked at me except my hairdresser, who made a disparaging remark.

"Little yappy dogs, the way they go off about nothing," she said. I glanced at Wolf, who could have, if he'd wished, inhaled Fluffy. He was glued to the floor, quaking in terror.

MY EXPERIMENT AT THE HAIRDRESSER'S raised more questions than it answered. Why, why did people avoid a dog they could not see? And now that I'd seen the incredible departure from the rule-why did visible animals see an invisible dog? Why did Fluffy, and the bullmastiff who had glared at Tidbit, and the Invies' littermates, see what humans did not? These questions made my head ache. It was time to call Evie for advice. I picked up the phone and told her all about it.

"Evie," I entreated, "is there a way that humans can see something, but not be conscious that they do?"

"Oh sure! There's a doc.u.mented phenomenon called ainattentional blindness.' In the cla.s.sic study, they made college students watch a film of a basketball game and count the bounce shots. A woman in a gorilla suit walked onto the court, in the middle of the game, beat her chest-I love that part-and walked off. So, like, only four percent of the students who saw the film noticed the gorilla, which is totally what my students would do. Does that help?"

"Maybe . . . but the people who didn't see my dog also stepped out of his way."

"Uh. Just a minute." I heard a young voice, a student; Evie was talking from her lab. "Yeah, uh . . . actually, that sounds like brain damage. Like people whose vision input doesn't process normally, so they're technically blind, but they navigate around things."

"I'd have to a.s.sume that everyone in the salon was brain damaged. And what about the other dog that saw my dog?" I waited, while the student's whine rose in pitch to a pure primate screech.

"Uh . . . Sophie . . . think strategies, okay? It's like, they mate with other dogs, that's a reproductive strategy, but they steal from humans, that's a survival strategy, okay? Gotta go."

"Thanksandgoodluck!" I rattled as the cell phone went dead. On a sheet of paper, I scribbled the words inattentional blindness.

WINTER CAME. My original question stayed unanswered. I continued riding out with Lucas. Winter near the Canadian border is a fearful time for dogs whose owners aren't paying attention. Sometimes at night, I dreamed that the city turned upside down like a chandelier, from whose snow-grimed, crystal-coated chains hung, frozen alive, dogs by the hundreds, creaking as they swayed. The city police visited the Society to inspect the bodies of three spaniels who'd been nicknamed "the dogs of Christmas," whom I don't want to remember. Maybe Evie had a point: maybe the human race was brain damaged. My home in the woods, in this season, provided a respite from scenes of neglect and moral abjection. The gelid January sunshine shone brightly there, from snowstorm to snowstorm, and in the drifts I saw necklaces of coyote tracks, circling toward rusty smudges where rabbits had uttered their last screams. Those circular tracks were the pattern of hunting wolves, I knew-coyotes were also called "prairie wolves"-it was the behavior on which shepherd dogs' training was based. Outside my home, two evolutionary paths showed as distinct as black and white: pethood versus wildness. Inside my home, the path was not so clear. What was Wolf, the invisible shepherd? Science, in the form of my brilliant sister, was not helping.

But I was willing to wait for answers; after all, hadn't time been on my side where my Wolfie was concerned? We'd come a long way. I had trained him in basic obedience. And he had trained me, revealing a most un-Invie-like fondness for ma.s.sage. He would fix on me a spangled brown gaze, and in a very eloquent way, fold his ears to expose the petting surface between them. If I didn't respond, he would thrust his head into my hand, to stimulate it, exploiting a human impulse straight out of some painted cavern in my brain. Whenever I took the time to ma.s.sage his whole spine, skull to tail, I surfaced from that drenching in animal softness, in likeness and alienness, with the giddy rush that is our vascular reward for petting a dog; the lowered blood pressure that is the upshot of thirty thousand years of mutual evolution. My heart would open down to its molecules. So we shaped each other, and were satisfied. Now, when I lit my fire and sat before it, my dog knew better than to steal my crackers. He took them from my hand and placed each cracker on the floor, to lick it, nudge it, give it some thought. Like his human, he had a contemplative personality. When he finished eating, a wolf's shadow rippled through the firelight on the wall. Then my dog laid his head on my knee, curled his tail around my other knee, and deposited all his paws in my lap, as if for safekeeping. I ran a finger up his nose, and he shut his eyes. Whatever this invisible dog was, we were family. We were a pack.

ONE WET SPRING MORNING, outside my house, a loud horn honked. A brown UPS truck was parked, the driver's cap at a strange, stiff tilt.

"Ma'am!" he shouted. "I can't come down with that attack dog loose."

"What? What?" As I stepped out, the rest of his words got scrambled in a gust of raindrops and an almighty din, a forceful, ground-ringing noise. An animal was performing a dance in the wet pollen on the driveway, a ferocious, leaping-it was-my G.o.d! My dog. He was a vision of tawny muscles and flashing teeth. He sounded like all German shepherds: his bark was law, authorized at state and federal levels. WOOF. My invisible shepherd was visible. And I'd never taught him "heel."

"Wolf! Sit!" He paused long enough to throw me an incredulous look-"Sit," in this crisis? The UPS guy blenched, handed me my package, and backed his truck off, with gingerly twists of his tires, followed by the reverberations that Wolf found necessary to add.

"Good boy," I said, finally. Wolf became a sphere of coa.r.s.e mist. Then, with a proud grin, he licked my hand and trotted into the hostas. I was laughing. I sat down on the porch step, smacked the soggy oak pollen, and yelped with laughter. The riddle of the past year was finally answered, and like all good riddles, its answer was ridiculously obvious.

The invisible dogs were pessimists, the cynics of dog-dom. They had no faith in pethood. For millennia, as long as dogs and people had shaped each other's natures, the Invies had trained us. They trained us to disregard them while they scavenged in our homes. Our eyes registered their presence, our unconscious minds took note; still, we ignored them. Good animal trainers that they were, just as we had refined wolves' natural hunting patterns, so the Invies had refined our natural penchant for inattentional blindness. For every yard dog licking its frozen chain with a torn tongue, or gasping away hours in the beating sun, an Invie lived in comfort through having trained a human to overlook its very existence. Obediently, we neglected them: we did not pay attention. They knew us better than we knew ourselves.

But Wolf was the exception! He had stopped being invisible because he much preferred ma.s.sage. He regarded me as a uniquely valuable pack member, well worth protecting against UPS and like carriers, and had cheerfully restored himself to human sight! To reverse millennia of blindness, all it took was a little attention, a little for Christ's sake love and attention . . .

I sat grinning in the drizzle. I'd been a fool not to see it before. Now that I saw, I was still a fool, thoroughly a fool-the sort you find in the Tarot deck, a vagabond in cap and bells who strides along blindfolded, without stumbling, because he sees through the eyes of the happy dog bounding by his side.

8.

In the human body, there are ten times more bacterial cells than human cells. Your body is a wilderness that bacteria colonize and tame. This does not diminish us-quite the contrary, it magnifies us to the dimensions of biomes; and perhaps the key to understanding ourselves as animals among other species is to be able to see the meanings of our lives in such unfamiliar, though accurate, proportions. Air Liners reveal a magnificent portrait of our human selves painted with the pointillistic brush of bacteria.

Air Liners TO APPRECIATE AIR LINERS you want to be in a bedroom at an intimate moment, and if you can observe invisible creatures, you'll see an amazing display.

You'll see something like a greenish-blue, translucent, spherical sculpture, composed of tangled legs, elbows, knees, rising and falling trunks, hands shuttling everywhere on long arms, fanning hair, arched necks, curled feet, and glinting rows of teeth. Although made by only one couple, the sphere is crowded with lots of faces-sprouting from a shoulder, lined up in rows down a flank, or staring out of a b.u.t.tock, blurring from one intense expression into another, eyes popping open, sparkling, melting, or fiercely shut. The limbs and members of the sphere look hollow, and the blue-green light seems to shape them out of the air, glowing and fading. Erotic acts in which the bodies join happen in visual overlaps, so that the fingers of one body are visible between the hips of the other, locked mouths surround a forked-looking tongue, and the female belly sits atop a telescope. These varied, blue-green, hollow forms of the act of love surround the solid human bodies that produce them, which are scarcely discernible except as a dark core around which the sphere shines and coruscates, like tubes of blown gla.s.s continually emerging around a hidden mouth.

You're looking at Air Liner microbes. Mammals having s.e.x produce biochemical triggers attracting the Air Liners (otherwise, they might be seen around people and animals who aren't having s.e.x). But if chemistry draws the Air Liners to us, what creates the glowing sculptures in our bedrooms is electricity-specifically, van der Waals forces. These are the most relaxed, mellow forces of electrical attraction. Van der Waals forces get a lot of work done in the world, more by seduction than compulsion-they're very far from the death grip of strong nuclear forces, or the wedlock of chemical bonds. What van der Waals forces feel like, I'd guess, is like knowing that you can resist something and doing it anyway. Here is what they do for Air Liners.

Imagine a human body pa.s.sing through air, leaving behind it, very briefly, a human-shaped tunnel. A hand would make a five-fingered tunnel as it traveled. But since air is a dense mix of particles and creatures-dust, spores, bacteria-as our skin pa.s.ses through this thick mixture, it leaves behind a fleeting electrical wake made of charged molecules. We're like spoons going through pudding, leaving a sticky, hollow wake. Air Liners get stuck to this electrical wake of our moving bodies by van der Waals forces. Once they're stuck, the show begins. A few Air Liners sticking to the hollow wake of a human body will explode, in a second, into colonies carpeting the entire tunnel and glowing like wildfire. They are creatures that generate light-bioluminescence-the same light seen during a red tide event, when ocean waves look floodlit from within; the difference is that Air Liners light up the tunnels in air. If the same body pa.s.ses again through the same spot, backtracking-as people do on the limited area of their beds-the Air Liners will simply carpet the new wake. This accounts for the multiple and overlapping body parts in the glowing spherical sculpture.

Why do Air Liners flock to our bedrooms? The faint charge that we create helps Air Liners depolarize their cell walls, to split themselves into new generations. As we couple in pairs, they divide by the billions. Why do they like mammals? I'd guess the attraction is our fur, or hair, because of what I once noticed after a New Year's Eve party. Lying in a dark room, before a dying fire, I saw a golden line around the shadowy profile of my body. The same nimbus-like line was tracing my lover's rec.u.mbent form, in which no features could be seen. We were two black forms outlined in a thin thread of energy, two human-shaped eclipses. Squinting hard, I saw that the sparkly look of the line was due to a near-imperceptible flickering where our body down was agitated by air currents. This was my first sighting of Air Liners after the party, so to say-Air Liners whose bioluminescence was fading from blue-green into lower, red-gold frequencies, as they settled like tired migrating birds onto the st.u.r.dy stalks of human body down.

There are so many questions about invisible animals that I cannot answer without the help of science. How many species of Air Liners exist? Do their populations differ from place to place, mammal to mammal, even person to person? Might they accompany each individual-be it human, dog, cat, or mouse-in dedicated colonies, throughout his or her s.e.xual life? Imagine that! Your personal Air Liners, like the chorus of a Greek drama in which you played the starring role, revealing the shapes of your secret acts.

But even if people besides me could see these invisible followers, and were curious enough to take notes during the heat of their embraces, I doubt we'd learn much about what we are from Air Liners. They illumine what we were a moment ago. They show the river we have stepped out of. At the core of their airy, translucent sphere is the solid, dark point of our presence-a point always in the present moment, from which we are thrown toward and into each other, in irresistible collisions. Love is always happening for the first time. And whatever makes it like that is a mystery streaming down from our proper persons into the river of all life, in unbroken shadow.

Imperiled and Extinct Invisible Beasts

1.

A poem called "The Kraken" by Tennyson describes a monster of the ocean bed, over which loom "huge sponges of millennial growth and height." It didn't occur to Tennyson that the Kraken itself might be a sponge, but that is what I deduce from observations and a tiny sample. I discovered the Kraken while on a trip to Antarctica with my sister, who generously invited me to join a research expedition to collect ice core samples. In return for making myself generally useful, I got to observe snorting leopard seals, projectile-p.o.o.ping penguins, and barnacled whale tails within inches of my nose; and to feel the strange thrill when a ship disappears into the frigid pink dusk, leaving your group to fend for itself. One day, hiking on a glacier, we climbed, one by one, into a deep creva.s.se-the kind that John Muir was tempted to die in because it resembled the mind of G.o.d, a.s.suming that G.o.d's thinking is fluorescent blue. In there-suspended like a spider by ropes, pulleys, and ice screws-I hacked off, with my ice ax, a tiny tip of Kraken. n.o.body else in our group saw it; I asked them all, later. n.o.body had seen anything like that.

The Antarctic Gla.s.s Kraken ANTARCTICA IS HUGE. Not that other places aren't huge, too, but this s...o...b..und continent devoid of human cities seems as huge as the winds, bare of any distraction from its icy vastness. To grasp the southern continent's scale, and picture the climate changes happening there, we often resort to comparisons with the civilized world. When the La.r.s.en-B Ice Shelf collapsed in 2003, glaciologists groping for the right words said that it was like Rhode Island turning to water. How apt for such times, I thought, when Providence seems all too fluid. And where does a state-sized Antarctic ice ma.s.s go when it melts? Into an undersea trough, scientists tell us, that is twice the size of Texas. That figures. Twice Texas must be just the size of h.e.l.l, so I don't wonder that by Antarctic standards, it's getting warm down there.

It's so warm that the Wilkins Ice Shelf, which collapsed during the writing of this book, is the first doc.u.mented breakup of an Antarctic ice shelf during winter. A short time ago, fifteen thousand square kilometers of Wilkins was clinging to the mainland by a thin beam of ice, like somebody who has stepped out of a fortieth-floor window and is hanging onto a ledge by one arm. Wilkins's ice arm was a mere three miles wide, but recently it broke up again and is now about one mile wide. So it goes.

When the Antarctic ice melts-when 70 percent of the world's water, and eight hundred thousand years of its ice-locked memories, turn to flood-we will see the Gla.s.s Kraken revealed.

The Kraken is a gla.s.s sponge: a Hexactinellida, the most common sea-bottom-dwelling creature in Antarctica's chilly waters. The ordinary gla.s.s sponge is a fairy-tale creature, a gla.s.s horn of plenty that spins itself, sometimes extruding branches like diaphanous sleeves. Most are no more than a foot long, but the Kraken is the regal exception. It is very big. Picture a map of Antarctica and you're looking at the Kraken. It grows from a thin layer of water lying between the base of the Antarctic ice cap and the continental bedrock. The Kraken has been growing for a long time, with ice and snow gradually settling in and around and on top of it; its tallest branches are supported by the ice, which froze into place as they followed the water layer. Possibly, the Kraken began as separate communities of gla.s.s sponges that merged into a single, gigantic colonial sponge.

If you could look through the imblued walls of glacial chasms (and if you could see invisible beasts), you'd be dumbstruck at the vision of the Kraken's branches sprawling like exurbs and subdivisions off the megalopolis of its body proper. Like all gla.s.s sponges, the Kraken conducts electricity, and in the darkness of the bedrock, faint, boreal lights pulse across its webs. In its entirety, it would look like the nighttime panorama from an airplane descending over Manhattan, Tokyo, or some fabled imperial seat-Atlantis City before it drowned.

Yet the Kraken is merely an animal; a sponge, so primitive it hardly qualifies as an animal. Did I say "its body"? Sponges have no body organs, no muscles, no nerves, no digestive systems. Whereas a microscopic water flea has the same striated muscle cells that you have. Such sophistication is light-years beyond your ordinary sponge, which is, basically, an entropy-reducing pocket in the water that perpetuates itself. And this unconscious thing, this jelly without a belly, makes gla.s.s-a major industrial product-the way you make daydreams, effortlessly, under the cold deep ocean.

How does the Kraken survive in ice? Sponges normally consume organic particles suspended in water. But the Kraken partners with special bacteria that happily coat the undersides of glaciers. These bacteria coat the Kraken's incurrent ca.n.a.ls, and in exchange for safe housing, they supply the Kraken with all the energy it needs. Nothing is impossible if you know the right bacteria-not even a primitive animal the size of a civilization.

When the polar ice caps become polar puddles, Antarctica's stony desert will stand naked. Perhaps, by then, others beside myself will confess to seeing invisible beasts. If they do, we should all hire a boat and go have a look at the Kraken. We won't need rabbit-fur hoods anymore to shield ears from frostbite, and lungs from ice motes. But if the world is still making gas masks, we'll need them against the poisoned miasma of decayed Kraken. I suspect it will be nighttime, the long night of the Pole. I imagine it like this.

There's the dark firmament, and across the stars, the green twisting beams of the southern lights. And the Kraken, exposed. Someone remarks that it looks like acres and acres of construction, all the scaffoldings raised and the beams in place, but smashed by a meteor or an earthquake. Someone else comments, in a morose tone, that while the Kraken looks man-made, it was just an innocent, peaceful animal trying to live in its niche. Our cities, our human civilization, destroyed it. To compare the Kraken to anything man-made is an offense against nature, blurts this morose person. Everybody starts honking out various opinions through the rubber snouts of our gas masks until we feel better or worse. A journalist records our comments. Meanwhile, the boat churns slowly past the view. Silhouetted by the unearthly green aurora, as far as the eye can see, rise the endless, skeletal skylines through which the stars shine.

2.

In selecting material for this book, it was necessary to exclude my ancestors' abundant accounts, though I have made use of them. An exception is the following tale compiled from Granduncle Erasmus's notes. Erasmus was a well-traveled man. Starting out in the merchant marine service at the turn of the twentieth century, he became an itinerant jack-of-all-trades, picking up odd jobs in ports around the world, often trekking inland on the fringes of a scientific expedition-zoological, geological, archaeological. In the notes written on these trips, he always disguised the names of destinations, perhaps to protect the expeditions from rivals or treasure hunters. He would label places with exotic names impossible to find on a map, usually names of women. I chose this tale, not only as a fond tribute to my late predecessor, but also because I was able to see and independently verify the existence of the invisible spider. I have made some additions to fill out and connect his notes, including a comment on the spider I witnessed; the latter is in square brackets and signed "Sophie." I do not know the location of the city called Theodora, which vaguely resembles Washington, DC.

The Spiders of Theodora THE CITY SWALLOWED by an earthquake was a planned city; the earthquake was not in its plan. Had the city's story ended there, it would have left us with only a trite human irony. Instead, its legacy is a natural wonder: a lost city imprisoned within the invisible domed web of gladiator spiders.

If any city had to be taken over by spiders, Theodora fit the bill. It was originally designed in the shape of a web, with broad, radial avenues crisscrossed by concentric rings of streets. The idea was to make the city airy, light, and easily navigable-like a spider's web; and on many strands of this handsome metropolis glittered, like dewdrops, impressive bronze and alabaster monuments. Equestrian princes, generals with c.o.c.ked rifles, saints with melded palms stood posturing along every citizen's daily rounds. Armies marched on a thousand carved pediments above tireless caryatids. Every day in that city dawned through a mist of its memories, and the sun, with a tropical glare, reflected off the faces of the famous dead. Although Theodora was not ancient, it loved to commemorate the past, and did so with youthful exuberance.

AT THE CENTER OF THEODORA'S urban web was its proudest edifice, the Commonwealth Baths. Modeled on ancient Roman baths, the Commonwealth brought all segments of society together. Any ragpicker who paid admission might leave a tattered T-shirt in the same row of lockers (decorated with cast-iron, dolphin-riding nymphs) where a minister's valet was hanging a sw.a.n.k suit-although the valet, carefully setting out pumice and brushes on a monogrammed folding bench, would keep a sharp eye on the ragpicker. The Commonwealth was democratic in a middling sort of way, below the standard of the Israeli kibbutz but above the US federal tax code. Everyone's feet, whether pedicured and sleek or callused and rough, could steep in the scalding baths and prune in the cold plunges together. As in Rome, the baths offered many enjoyments. You could work out at a gym, go shopping, meet friends, make the rounds of taverns. You could hear a political debate or a concert. You could even hire a mechanic to ride out to the magnificent crescent of parking structures surrounding the Commonwealth and give your car a tune-up while you bathed. But these amenities were accessory to the main ceremonial purpose of the baths, which was the promotion of public memory as much as public hygiene. As soon as you stepped out of your clothes and into the warming room, where you sat on a wooden bench as comforting as a loaf out of the oven-to adjust yourself to higher temperatures-your eyes rested on memorial after memorial of the city's venerable history. Statues of heroes sweated condensation from their straining visages. Philosophers peered into volumes of shining granite from which mists curled. In the cold baths, quaintly lettered texts of the city's founding principles rippled along the mosaic floors of the clear, echoing pools, obscured by foam thrashed up by the clean-limbed citizenry. In the sauna, each red-hot stone was carved to symbolize a problem that the city had once faced, conquered, and sent (as it were) to h.e.l.l: a foe, a plague, a deflated currency. The crisp, heavy-weight public towels were bordered with embroidered dates; you wrapped your body in the calendar of the past. What a proud city it was! How it loved to commemorate the past! What a strange fate befell it!

NOW, AS YOU MIGHT HAVE GUESSED, the city planned in the shape of a web was friendly to spiders. Its folklore celebrated them, in fact, perhaps because so many kinds of spiders lived in the city. If, on a summer's night, a young couple neared a park bench perfect for kissing where a three-inch wolf spider crouched, the young man did not try to slay the monster. He would wave one hand like a flag of peace, and the wolf spider (who always hides from people) would slink from her hunting perch with a wary air about her eight-leggy figure. A spider's egg sac in your window was considered good luck; you could buy fake ones. I should add that Theodora was a seat of government, in which the opposition party had always been called the "fishing spiders," because, like their namesakes, they had to run on water to get back into power. Members of the s.e.x Workers Union, always an important pacesetter in a political town, liked to wear cleavage-catching pendants in the shape of bolas spiders, who toss hormone-soaked lures in the direction of male moths and rope in their s.e.x-befuddled prey. Spies, of which the city had an abundance, both native and foreign, were creepily nicknamed ant spiders, after the arachnid spooks who infiltrate ant colonies by walking on six of their eight legs, waving two forelegs to simulate antennae. And no garden was considered complete without its plump, spiny, orange orb-weaver spider hanging in the middle of a spiral web, treading along the non-sticky threads, dodging the sticky ones, and adding to that mysterious stripe that looks like a gossamer zipper and cannot be explained by human science. That's why people liked it.

IRONICALLY, THEODORA TOOK NO NOTICE of the gladiator spider, a uniquely talented spider that lived there in large numbers. This is not the same as the Namibian Palfuria gladiator, so named for the male's extra-large palp. No, these gladiator spiders are invisible, which explains why they went unnoticed despite their extraordinary skills. Like the gladiators of ancient Rome, they fight with nets, throwing a web around their prey and imprisoning it in a domed structure. Unlike other net-casting spiders, who wrap their prey like a sandwich, gladiators create domes so tough and rigid that the vibrations of the struggling prey within cannot be sensed by other spiders in the neighborhood. This is a clever way to discourage food thieves. It follows, therefore, that the gladiator spider herself is also exquisitely sensitive to vibrations. For instance, like the fishing spider, she can sense the vibrations created on the surface of the water by small swimming prey. Sometimes she detects and dives for tadpoles or newly hatched minnows, spinning an underwater dome that captures a small air bubble along with the catch, giving the spider an air tank. Gladiator spiders are barely an inch across, but very brave: they eagerly tackle big game. A gladiator spider can, in fact, capture a stag beetle the size of your middle finger.

[I saw this happen on television during a political debate between two candidates for high office. The mortal combat took place on top of one of the candidate's toupees-that's how I could tell that it was a toupee, because anyone with real hair would have felt something. You really can't have a big angry beetle, waving its claws, imprisoned on the top of your head under a silk yarmulke woven on the spot by a very active spider and continue gabbing on about faith and family and values as if nothing unusual were happening, unless you are wearing a toupee-a stiff one.-Sophie.]

ON A CLEAR SEPTEMBER DAY, an earthquake swallowed the city whole, from the tips of the obelisks to the bolts on the manholes, in less time than it takes to read this sentence, and the city's founders, had they still been alive, might have written with a flourish, FINIS; but Mother Nature's work is never finished.

In those horrifying first seconds, Theodora came apart in large segments like a dropped layer cake; districts that had been adjacent were now perpendicular. A smothered death-scream tore through the earth, from the mouths of everyone trying to find out where he or she was. The composer never lived who could imagine what it sounded like-and never should. Every creature on two or four feet fell down and slowly asphyxiated. Pigeons, sparrows, hawks, robins, cardinals, orioles, and flycatchers dropped out of the black air like suicides; dogs, cats, racc.o.o.ns, mice, squirrels, chipmunks, snakes, toads, a few mangy coyotes, and a lone black bear tumbled or crept to their deaths. Even the rats died. Bacteria began their long feast. In the Commonwealth Baths, whose skylights were plugged with total darkness, the s.p.a.cious, venerable pools and graceful porticos seethed and dripped sc.u.m as the clear waters of health became tarry sumps of skeletons.

Yet, for a time, curiously, Theodora was full of life. Had a human being been able to witness the aftermath of the catastrophe, he or she might have reflected that as Rome was saved by its cackling geese, so this buried city was preserved by its gladiator spiders, in one of the greatest feats any creature has ever performed.

WHEN THE EARTHQUAKE HIT and the city roared down into the earth's canyon jaws, the gladiator spiders resorted to their three great gifts: sensitivity, engineering, and courage. Clinging to the city, they sensed its seismic shudders, and they gauged the giant size of this new vibration, while their body hair picked up the scent of edible tissue trapped inside the city's crumpled architecture. To the spiders, the event felt exactly as if the world's biggest prey animal had challenged them to a match. Bravely, they rose to the challenge. In an unprecedented move, every gladiator spider joined with its fellows and began to spin a web of scale. Perhaps they'd been social creatures all along but hadn't needed to band together before-or perhaps it was a fluke, a one-in-a-billion chance that they would all start spinning simultaneously. Either way, the gladiator spiders' consortium, in the very teeth of catastrophe, spun with as much cool purpose as if every pumping, leaping, twirling little spinner had been possessed by the ghost of Buckminster Fuller. Soon the whole shaking city was encased in a vaulted silk dome with air pinned inside it. There wasn't enough oxygen to save the people or animals (except for the kinds of worms that breathe the air in dirt). There was enough air, however, to save temporarily the gladiator spiders, thanks to their book lungs. Book lungs are how spiders breathe: layered blocks of tissue, like tiny books, through the "pages" of which gases percolate. In gladiator spiders, the pages are very thin and densely packed, like little Norton anthologies of literature, allowing oxygen to be used more efficiently than in other spiders' book lungs, which resemble quickly read best sellers. That is the reason why, after the buried city's other beasts had perished, the gladiator spiders, armed with an encyclopedic breathing apparatus and the courage of intellectuals fighting the death of their ideals, stayed alive. While they lived, they kept spinning. They went after the edible tissue inside the ruins-the corrupt flesh of animals and people-and roped, levered, tugged, and suspended in their silken larders whatever they found to subsist on. Mult.i.tudes of skeletons were thus hoisted upward, into the great dome, like bones in the vision of the prophet Ezekiel, who saw a valley of skeletons rise and stand again. But these bones did more than stand. They levitated. Like angels and swans swung through opera theaters on invisible ropes, they hung in the dense mesh of the gladiator spiders' webs.

Now, recollect that if you were to see the city inside the earth, you would not see the gladiator spiders or their webs. You would see only the image of a meta-memorial: a memorial to memorials. You would see Theodora's monuments-those alabaster and bronze statues that used to glitter along its avenues-collapsed in violent heaps where the saint's nose is rammed against the cracked breast of Justice, and commanding hands, as heavy as motors, point from under buckled pavements and open expressively out of crushed walls. If you will pardon the comparison, imagine a snow globe with the monuments as its plastic scene and the disconnected bones as snow. It's like that, except that the city doesn't shake anymore, while the bones, secured by natural causes, float forever in place.

3.

Animals can teach us, and the Foster Fowl was the most extraordinary teacher alive. It hurts to think that I may have had a hand in its disappearance, and when my conscience starts to p.r.i.c.k, I go over the whole episode inch by inch . . . all the way up the "escalator to extinction."

The Foster Fowl GO OUT ON A JULY DAY, when from a high branch a robin pours out its carol like a general blessing, along with a flycatcher's whoop, an oriole's note, and the melody of a song sparrow that springs alike from earth and air. Go out, take a pair of kitchen shears. You can smell the tall milkweeds, with their flowering globes like old-fashioned microphone heads; they're broadcasting a summer special that brings in the bees, bent double with effort, and the monarch b.u.t.terflies who have mated tipsily in the air and now, female by female, stately orange and black-deckled, land to lay their eggs. Across your path, a hummingbird arches in an inch-long arabesque-with a diminutive roar she chases off a wren, trailing her battle cry: Squeaksneeterie!

Go to the purple lavender smoking on its naked stems. Respecting the bees, whose business here is more important than yours, cut yourself a bundle, take it home, wash it, cram it into a clean Ball jar, and fill the jar with honey. Seal it tight and take it across the road to your neighbor's farmhouse. Exchange it for a half-dozen eggs lifted out from under their mamas, still warm, and take them home on a chipped plate that you set on your porch corner, just inside the screen door. And she'll come. Or she would till lately.

You won't see her actually arrive. If the eggs are placed out for her, she'll just be there, like the Beatles song about Mother Mary: "When I offer chocolates, she is standing right in front of me." Although I misheard that song: "In my hour of darkness" were the correct words, but I always thought that Mother Mary would come when you made her an offering suitable to her place in the natural scheme of things. If you put out a golden box of fine chocolates, like the platform of a Byzantine throne, she would appear, drawn to the odor of your prayer, her blue mantle brushing the lid, her eyes piercingly gentle.

Anyway . . . put the eggs out, and soon, in that humble porch corner, a creature appears like an azure wave from some transparent sea, mantling the eggs and crooning, cro-coo-roc, cro-coo-roc. As you recover from her stunning plumage-peac.o.c.k, aqua, lacustrine-you see that she's rather comical. Her build is between a pheasant and a small wild turkey. Her neck is a lapis pipe; she fixes on you a gaze the color of pineapple meat; her short, curved, turquoise beak resembles nothing so much as a pair of plastic-coated sewing scissors. She has no hard feathers, but is entirely covered in iridescent down-a silken mop, a turkey shawled in sapphire threads, and over her head droops a crest like an unraveled pompon. And she's as soft inside as out: she can't resist a clutch of foundling eggs. But unlike any other mother bird, she won't defend her nest.

So begin the game: steal her eggs, her newly adopted chicken children, by scattering corn outside. She'll unseat herself like a shimmering cloud, rise on indigo stilts, bend her long feet as if inserting them into high-heeled pumps, and quickly tiptoe out the door to graze, for she's very hungry. When your Foster Fowl returns to find her eggs in your hands, she doesn't rush you screaming or stab her blue beak in your blood. Instead she glides to the trees bordering your yard, teeters there, a silvery teardrop, and melts away into the forest. Now, now she is your quarry to be pursued with eager questions. How many species, and which, will the Foster Fowl incubate? How many avian species owe a boost, and how many abandoned broods owe their success, to a mother whose all-enfolding love does not discriminate between her kind and others?

I LIVE NEAR A SPOT known as the Warbler Capital of the World. In spring, bird fanciers from all over converge here, on a boardwalk surrounded by marshes, to jostle fiercely for position, sometimes even erecting their camera tripods over the heads of other birders who have knelt down to peer into the brush, binoculars at the ready, oblivious. Complete strangers, standing cheek by jowl, exchange intelligence on the likeliest location of the blue-headed vireo or the ruby-crowned kinglet. Men dressed like hunters tote weapon-sized lenses; old couples bicker in soft voices over their lists of "life birds"-a life bird is one that you see for the very first time. Ten years ago, it didn't occur to me that the first Foster Fowl to visit my porch-my own life bird, whom I nicknamed "My Blue Heaven"-was anything but an accidental. Something soars overhead looking for Nova Scotia: that's an accidental. But My Blue Heaven wasn't, after all, an accidental: she hadn't gone out of her way at all. She was a harbinger.

I'd discovered My Blue Heaven brooding a plateful of new eggs I'd laid down momentarily, and the game came about by accident. When she fled into the woods, I decided to track her. Since she was obviously flightless, the best method was to seek the nests of birds that laid their eggs on the ground, and might attract her. While consulting Peterson's long list of these, I noticed something curious: many birds were shifting their ranges northward. I should have thought! Birds as different as the tiny blue-gray gnatcatcher and the lumbering turkey vulture were moving northward. Why didn't I put two and two together? What was I thinking?

I ought, I ought to have wondered what a blatantly southern bird like My Blue Heaven, with her morpho b.u.t.terfly looks and her uselessness for winter, was doing near Lake Erie. She must have walked, maybe all the way from Florida. And after her, I saw only females (except, memorably, once). Why? Why didn't I mull it over? Because I was stupid. Because I was having too much fun, finding out which eggs the Foster Fowls mothered, as if nature had developed a new summer sport for my benefit. All for me, I gloated, setting the lure of the orphan eggs, sprinkling the trail of corn, and finding the world's most beautiful blues in a downy cloud. All for me, the thrill of tracking. How many of us are philosophical enough to question the whys and wherefores of a pleasure? I wasn't, as I hot-footed it into the summer woods. All for me. Imbecile.

TO FIND A FOSTER FOWL in the greenwood wasn't easy, because only in pursuit of a blue creature does one appreciate how much blue there is in green. Where eyes failed I tried ears, parting the brush between trees, listening. Phew! called the veeries back and forth, and Freebie! freebie! screamed the phoebe, and Truly to thee, sang the bluebirds, and the killdeer, whose species is Vociferus, was, and Wheat, wheat, wheat to you, sang a cardinal whose babies shrilled Feed-me-feed-me-feed-me-feed-me. I went to the marsh around my pond, and spent hours crouched under tickling gra.s.ses, binoculars glued to my eye sockets. The pond, at the bottom of a quarry, continuously reflected a quivering, linear, blue light that caressed the stone walls, and where the walls met the water stood cattails and reeds. That's where I found My Blue Heaven. For weeks, I studied the volitional shimmer that gave her away, that wasn't sky or water or light, but a maternal breast. I grew very curious, because no pheasant can swim like a duck . . . but when the time came, there it was: a bobbing chain of ducklings, dabbling, shaking their baby rumps, in the ripples and on the sand beside My Blue Heaven's hiding place.

In later years, I followed my egg-deprived Foster Fowls to the nests of mute swans, Canada geese, woodc.o.c.ks, whippoorwills, bobwhites, and once, a kingfisher, and never discovered how they did it-how they taught the young of other species. But somehow, they did.

In those years, I could count on three or four Foster Fowls in a summer. I never saw their chicks: not one blue puffball, and I wondered (though not enough*). Where were their mates? A pheasant female wandering, all alone, in search of abandoned eggs-why didn't this bother me more? Such birds live in harems with a territorial male. Nature doesn't make roving bachelor hens. Of course, invisible animals can be very different from their visible counterparts, but it was still odd. I knew that My Blue Heaven was an invisible bird because I'd tried to photograph her, but the pictures showed only an a.s.sortment of ducks, swans, geese, woodc.o.c.ks, and other ordinary birds. For some reason, invisible animals do not show up on camera. It is a great handicap to amateur naturalists of invisible wildlife, like myself, and it is a great pity. Especially considering what ultimately happened.

One day, I found my royal cloud sitting in a dent in the gra.s.s, barely a nest, on a clutch of creamy eggs that I glimpsed when she rose to turn them with her deft turquoise beak. I stared till my eyes watered, in the shadows where a pebbled sort of whistle announced a single, obsessed cricket.

"You crazy girl," I thought, "you insane bird. This, I have got to see."

And I did see, soon afterward-on my computer screen, as I scanned the photographs taken by my infrared camera. These pictures explained why the Foster Fowl needs to be invisible. Otherwise, she'd be a meal for the young owl caught-wings perpendicular between tree trunks-clutching a limp cardinal. How had she reared this raptor, whose habits were the cruel opposite of her own? How mysterious was the being that I hunted through summer after summer, her loving kindness as abundant as the air. My instincts became honed to clues I was not conscious of-hunches of the feet, guesses of the inner compa.s.s-that led me into ever deeper concealments, obscurer hiding places. I gagged at the sapphire on a ripe, torn corpse, crooning her cradle song as if a vulture's nest were purest myrrh . . .

TEN YEARS AGO, I saw my last Foster Fowl. It was an August morning. The bells, rattles, and whistles in the insect world rose into a sky stuffed with pale flames. Thwock! A walnut smacked the turf, just missing my skull. h.e.l.lo, gravity and time. I felt suddenly fed up with gravity and time and their boring threats; I felt put upon by natural law, and went into the woods swinging a long stick to sweep away the spiderwebs that I really had no business to ravage, given how excellent an animal a spider is. With that arrogance of ours, like some pompous bureaucrat in a Byzantine procession, I marched through the woods swaying my stick in front of me, tearing down what I couldn't see and didn't want to. I marched into a stand of oaks about four inches high. Each green shoot spread a top cl.u.s.ter of five large leaves, like a puppy's big paws. A stand of mighty oaks was trying to grow up here. Then I saw my Foster Fowl, in the spattered light. Her neck was sunk in her breast, while her candy-yellow eyes, swiveling toward me, registered broodiness, the mother love that belongs so completely to birds. (Only domestic hens are unmotherly, because we've bred it out of them.) Her throat inflated as she crooned. She looked as if a valve had opened beneath her nest, inside the earth where it was still a molten star, and was shooting a warm ray through her heart. After a while, she cranked up on her indigo stilts, shook out her wings, and went pecking among the infant oaks. I fiddled with the focus adjustment and heard my own voice, spontaneous as any birdcall: Oh no! Oh s.h.i.t! Oh, no.

And it was stupid to have marched over, crunching leaf litter under my boots. Stupid to have knelt by the woven nest-cup, putting my big human paw there, tossing eggs into the woods, good riddance to bad eggs, to thuggish cowbirds. I detest cowbirds. For every cowbird egg stealing s.p.a.ce in another species' nest, there's one more disappointment in the world. Okay, and it was stupid to have panicked when I found myself electrified, on my feet, backing away from a three-foot-high chunk of enraged lapis lazuli with ruby eyes and crimson crest, stretching out his wicked long neck with a blue beak and a black tongue hollering like a turkey on the warpath, Rotter-rotter-rotter-rotter-rotter-rotter-rotterrrrr! I took to my heels. Laugh if you like, it was terrible. I had finally met a male Foster Fowl. There was nothing soft in his feathers or his comportment. I'll never know whether it was he and his mate who wove the nest with that last, sole egg . . . that last egg at the bottom of the nest, which may, or may not, have been a Foster Fowl's. I came back later. The nest was moved. I don't blame them. I will never know.

THE NEXT SUMMER, I set out my chicken-egg lure: no Foster Fowl came, though racc.o.o.ns did. I waited all summer. The summer after that, I set out eggs again: no Foster Fowl came, though racc.o.o.ns did and trashed my porch with my own trash. I spent the summer lurking in all her usual spots; I watched the poor, bare eggs, in many an abandoned nest, s.n.a.t.c.hed up by squirrels, crunched down by foxes, engulfed by snakes. And the summer after that. And the summer after that.