Gulp: Adventures on the Alimentary Canal

by Mary Roach

  So Hunter was wrong. No vital force exists to protect a living being from the effects of the gastric secretions. Why is it, then, that stomachs don’t digest themselves? Why do one’s stomach juices handily digest haggis or tripe but not the very stomach that secretes them?

  It’s something of a trick answer. In fact, stomachs can digest themselves. Gastric acid and pepsin digest the cells of the stomach’s protective layer, or mucosa, quite effectively. What no one in Hunter’s day realized is that the organ swiftly rebuilds what it breaks down. A healthy adult has a new stomach lining every three days. (More clever stomach tricks: key components of gastric acid are secreted separately, lest they ravage the cells that manufacture them.) The stomachs of John Hunter’s cadavers managed to burn holes in themselves because the mucosa-producing machinery shuts down at death. If someone dies in the midst of a meal—particularly in a warm clime, where weather stands in for body heat—the digestive juices continue to act though the restoration work has stopped.

  If you must spend time in a digestive organ, I recommend the penguin stomach. Penguins can shut down digestion by lowering the temperature inside their stomach to the point where the gastric juices are no longer active. The stomach becomes a kind of cooler to carry home the fish they’ve caught for their young. Penguins’ hunting grounds may be several days’ journey from the nest. Without this handy refrigerated mode, the swallowed fish would be completely digested by the time the adults get back—“like going shopping and eating everything you bought on the way home,” as marine biologist Terrie Williams put it.

  ONE REASON THE notion of living principle gained traction in John Hunter’s mind was that it offered a medical explanation for stomach snakes. As far back as Babylon and ancient Egypt, people had been coming to doctors with complaints of reptiles or amphibians living inside them. The malady hit an especially brisk stride in the late eighteenth century. “Thence it is,” wrote Hunter in his 1772 paper on the living principle, “that we find animals of various kinds living in the stomach, or even hatched and bred there.” Through the end of the century and likely beyond, biologists of imposing stature—not just Hunter, but also Carl Linnaeus—believed that frogs and snakes could live in humans as parasites, nourished by daily deliveries of swallowed food. Medical historian and author Jan Bondeson tracked down some five dozen case reports in medical journals from the seventeenth, eighteenth, and nineteenth centuries. Eighteen involved lizards or salamanders; seventeen posited snakes; fifteen claimed frogs; and twelve toads.

  Despite the varied taxonomy and geography represented by these cases, the basic premise is more or less the same. The patient, vexed by odd sensations or pains in the abdomen, suddenly remembers a visit to the country. While walking home at night, the tale typically goes, he stops to drink from a pond—or marsh or rivulet or spring. It’s nighttime, and he cannot see what he is swallowing. Or he is drunk and does not notice. Sometimes he believes he swallowed eggs, other times the actual animal. In a few instances, the person lies down to sleep or passes out, whereupon some elongate, cold-blooded creature slithers down his esophagus and into his gut.

  What cements the delusion, in the patient’s mind, is the timely sighting of an animal in the chamber pot. “When at stool, she had unusual pain in the rectum, and afterwards she thought she perceived something moving in the pot,” reads a typical case report, from 1813. Often the patient has been given a cathartic to relieve his symptoms. As here, in the 1865 case report of a stomach slug: “The patient had taken an injection per anum* . . . and immediately afterward something attracted his attention by moving about under his clothes.”

  The likelier chain of events, of course, is that the creature had been in the pot or the bed, unnoticed, all along. And that the authors who wrote these papers were either lazy thinkers or, equally possible, crafty career opportunists. Cases like these, taken at face value, were irresistible medical curiosities; reports of them were sure to be published in medical journals and newspapers of the day, spreading the physicians’ names and boosting their status.

  Then again, to be fair, some of the details conspired to lend credence to the claims. Like the contemporary urban myth, tales of stomach frogs and “bosom serpents” persisted because they have truthiness. Few would believe a story about a man with a mammal alive in his digestive tract—though Bondeson tracked down one instance of a stomach mouse—but an indwelling frog has biological plausibility. Sideshow regurgitators used frogs because they can absorb oxygen from water through their skin. Swallow a frog in a large glass of water, and it will survive—at least through the end of the act.

  Cold-blooded animals in general have lower metabolic needs. Because they’re not using food energy to heat themselves, they manage with less. Some frogs all but shut down in winter. “I wouldn’t be surprised if live frogs were gutted out of bass in winter, by fisherman,” wildlife biologist Tom Pitchford told me. But a human belly isn’t cold. It’s tropical. Around 1850, in Germany, physiologist-zoologist Arnold Adolph Berthold, seeking to put an end to stomach-frog folly, put some northern European species of frogs and lizards in body-temperature water. The adults died, and the spawn putrefied.

  That snakes top the list is not surprising. On top of their overall cold-blooded hardiness, they seem to have a special knack for enduring gastrointestinal confinement. Phillip Clapham, the whale biologist I pestered at the start of this chapter, related the story of Gracie, a Doberman mix who once vomited a two-foot garter snake onto Clapham’s dining room floor during a dinner party. As he tells it, his wife at the time, assuming the snake was dead, picked it up in a wad of paper towels and then “nearly dropped it when its little forked tongue came out.” Clapham insists Gracie hadn’t been outside for at least two hours. “It had been in there quite a while.”

  University of Alabama snake digestion researcher Stephen Secor once watched a king snake regain consciousness after somewhere between ten and twenty-five minutes inside another king snake. He had put the two in the same tank, not realizing one species considered the other dinner. Secor left the room, and when he returned, dinner was “down in.” He pulled them apart, and was relieved and surprised to note that dinner still had a heartbeat.

  Nonetheless, a brief sojourn is different from permanent immigration. More reputable doctors of yore recognized stomach snakes for what they were: delusions inspired by gastric symptoms. The underlying condition was typically mundane: ulcer, lactose intolerance, intemperance, gas. You could often tell what was going on from the patients’ descriptions of their tenant’s habits. Andrew S.’s snake acted up whenever he drank alcohol or milk. “He will never allow me to drink whiskey,” S.’s physician Alfred Stengel quotes him as saying in the 1903 paper “Sensations Interpreted as Live Animals in the Stomach.” “He hates that worse than anything else.” The stomach snake of a woman in Castleton, Vermont, circa 1843, was most active after “any considerable indulgence in gross food.”

  Occasionally there was nothing wrong at all, just the ordinary grumbling and gurgling—the borborygmi—of the gut. The surgeon Frederick Treves, writing in the late 1800s, described five cases of patients complaining of wriggling movements or of live snakes inside them. Upon operating and finding nothing beyond the normal motions of a healthy digestive tract, he coined a term: “intestinal neurosis.” It exists today, minus the snakes. One gastroenterologist told me about a sad soul who wandered the motility clinics of North America with a video of himself in his underwear, pennies stacked on his abdomen to show the alarming motions of his (perfectly normal) intestines.

  Sometimes a patient would manage to capture the alleged tormentor and bring it in to show the doctor. While some physicians kept the animals for display in cabinets of curiosity—or, on occasion, as pets—those of a more scientific bent recognized an opportunity for forensic fact-checking. Jan Bondeson relates a famous case from the seventeenth century of a twelve-year-old who complained of abdominal cramping and, over an unspecified span of time, allegedly vomited twenty-o
ne newts, four frogs, and “some toads.” One of the youth’s physicians had the bright idea of dissecting the amphibians’ stomachs. If the story were true, the food inside the little stomachs should reflect the creatures’ gastrointestinal habitat. Instead the stomachs contained half-digested insects. In 1850, Arnold Adolph Berthold, our man of the putrefied frog spawn, approached curators at German medical museums whose collections included reptiles and amphibians allegedly vomited or excreted after years of residence in a human digestive tract. Here again, when specimens’ stomachs were opened, many were found to hold insects in various stages of dissolution.

  The most directed experimental debunking was carried out by J. C. Dalton, a physiology professor at the College of Physicians and Surgeons of New York. Over a span of several months in 1865, Dalton had twice been visited by flummoxed colleagues bearing “discharged” slugs in jars of alcohol. One was said to have come from a boy who had been suffering three weeks from diarrhea. The usual narrative ensued: “It was during this diarrhea that the slugs were passed. On that day, the mother, on removing the clothes from the child after a fecal evacuation, found among them one of the animals, alive and moving.” She assumed he’d inadvertently consumed slug eggs while eating garden greens on a family visit in the countryside, where the boy had “passed a part of the summer”—an alarming verb choice under the circumstances.

  Dalton was dubious. “I accordingly thought it worthwhile to institute some experiments, with a view of ascertaining how far such a thing might be possible.” Garden slugs were procured from a neighborhood lettuce bed. An assistant held a dog’s mouth open while Dalton placed four slugs, one at a time, at the far back of its mouth to get it to swallow without chewing. An hour later, Dalton took out his scalpel. He found “no recognizable traces of slug” anywhere along the dog’s alimentary canal. In subsequent experiments, just fifteen minutes rendered a slug “somewhat softened” and a salamander “exceedingly soft and flaccid,” and both dead.

  “It is a curious psychological phenomenon,” wrote Dalton, “to witness the thorough confidence . . . and the fullness of detail with which intelligent persons will sometimes relate these stories. . . . When the accounts come to us second hand, we can always make abundant allowance for the natural growth of wonders, in passing from mouth to mouth. But even when the facts stated are those which came under the relator’s own observation, the discrepancy between his convictions and the truth may sometimes be equally remarkable.”

  Wise words, no less applicable today. It is 2011 as I write this, and the story endures. Only now the lizards and frogs are on the outside.

  * * *

  * 1896 was a banner year for human-swallowing, or yellow journalism. Two weeks after the Bartley story broke, the Times ran a follow-up item about a sailor buried at sea. An axe and a grindstone, among other things, were placed in the body bag to sink the parcel. The man’s son, frantic with grief, plunged overboard. The next day, the crew hauled aboard a huge shark with an odd sound issuing from within. Inside the stomach, they found both the father and the son alive, one turning the grindstone while the other sharpened the axe, “preparatory to cutting their way out.” The father, the story explains, “had only been in a trance.” As had, apparently, the Times editorial staff.

  * I challenge you to find a more innocuous sentence containing the words sperm, suction, swallow, and any homophone of seaman. And then call me up on the homophone and read it to me.

  * Vallisneri named the fluid aqua fortis—not to be confused with aquavit, a Scandinavian liquor with, sayeth the Internet, “a long and illustrious history as the first choice for . . . special occasions,” like holidays or the opening of an ostrich stomach.

  * At some point during the experiment, or possibly the follow-up, wherein a live eel was pushed into the stomach and left with “just its head outside,” or one of the dozens of other vivisections, Bernard’s wife walked in. Marie Françoise “Fanny” Bernard—whose dowry had funded the experiments—was aghast. In 1870 she left him and inflicted her own brand of cruelty. She founded an anti-vivisection society. Go, Fanny.

  * Meaning “by way of the anus.” “Per annum,” with two n’s, means “yearly.” The correct answer to the question, “What is the birth rate per anum?” is zero (one hopes). The Internet provides many fine examples of the perils of confusing the two. The investment firm that offers “10% interest per anum” is likely to have about as many takers as the Nigerian screenwriter who describes himself as “capable of writing 6 movies per anum” or the Sri Lankan importer whose classified ad declares, “3600 metric tonnes of garlic wanted per anum.” The individual who poses the question “How many people die horse riding per anum?” on the Ask Jeeves website has set himself up for crude, derisive blowback in the Comments block.

  9

  Dinner’s Revenge

  CAN THE EATEN EAT BACK?

  THE DARKLING BEETLE, small and shy with an understated matte-black carapace, is better known as its adolescent self, the mealworm. Mealworms and their darkling cousins the superworms are popular “live feeders”—food for pet reptiles and amphibians that won’t eat prey that’s already dead. For years, a disconcerting rumor has bounced around the “herp” (as in, herpetofauna) community. Heed the words of Fishguy2727, posting on Aquaticcommunity.com: “I have talked to a number of people who have FIRST-HAND watched with their own eyes as the animal ate a mealworm, . . . and within ten to twenty seconds the mealworm is chewing out of the animal’s stomach.”

  I heard about the phenomenon SECOND-HAND from wildlife biologist Tom Pitchford. The mealworm came to mind when I asked Tom whether he knew of any nonparasitic creature that could survive in a stomach for any length of time. He had heard that some online herp forums recommend crushing mealworms’ heads prior to serving. “While the insect is in its death throes, the lizard will come over and eat it.”

  Mealworm ranchers scoff. “This is an old wives tale,” says Wormman.com. The owner of Bassetts Cricket (and mealworm) Ranch told me that a slice of carrot, for a mealworm, is a two-day project. “They can’t eat out,” he said. (Though obviously enough people worry about it that it has its own verb form.) But mealworm sellers have a financial stake in the matter. What do reptile and amphibian dealers say? Carlos Haslam, manager of the East Bay Vivarium, a reptile and amphibian store not far from my home, told me that in his forty years in the business, he has not seen the phenomenon nor heard a customer report it happening. He pointed out that lizards chew their food before swallowing. Frogs don’t, but lizards do. And most of the stories are about lizards. Fishguy2727 takes no comfort. “Just because 1,000 people have not had it happen to them does not mean it is impossible. There is no doubt that this can happen.”

  As so often is the case with apocryphal tales like this, finding someone who knows someone who’s seen it is easy. Less easy is tracking down an actual eyewitness. One who claims to have seen is John Gray, the animal care technician at the Tracy Laboratory at the University of Nevada, Reno. His boss, Richard Tracy, is a physiological ecologist. He predicts hotspots of future extinction, with reptiles and amphibians as his focus. Eighteen lizards, forty toads, and fifty frogs are under John Gray’s care, but he has not seen it happen to any of them. It happened to a fence lizard he caught in his backyard as a twelve-year-old. He recalls feeding a superworm to his new pet in the evening, and finding the lizard dead the next morning with the superworm “hanging out of its side.”

  Tracy is skeptical. He has a theory that the story took root in the public’s consciousness with the 1979 release of Alien, a film in which the title character hatches inside one of the crew and breaks through the skin of the man’s abdomen during a meeting. He questions Gray’s memory. Who can recall, with dependable accuracy, the details of an event that happened thirty years ago? One of the mealworm’s natural behaviors is to crawl underneath things. “Mealworms prefer darkness and to have their body in contact with an object,” says the University of Arizona Darkling Beetle/Mealworm Informati
on sheet, under the heading “Interesting Behaviors.” The sheet’s authors make no mention of mealworms eating their way out of stomachs, which would, you’d think, qualify as interesting behavior. As with the post-laxative stomach slug and snake sightings of yesteryear, it seems more likely that the worm was already on the scene, seeking darkness and framed by happenstance.

  However, like most people who work with captive reptiles and amphibians, Tracy has trouble completely dismissing the stories. He’s going to do what experimental biologists do in situations like this: experiment.

  PROFESSOR TRACY HAS borrowed an endoscope. It is slimmer than most because it was designed to look up urethras. The scope belonged to a urologist whose daughter studied tortoises at the University of Nevada. He lent it to her to look inside tortoise burrows, and she has lent it to Tracy to watch mealworms inside stomachs. What goes around comes around, and up and in and through.

  Tracy has no funding for the experiment, just enthusiasm. He calls up colleagues and acquaintances and tells them what he’s fixing to do, and they jump on board with offers to help. Walt Mandeville, the university veterinarian, has volunteered to do the sedating. Tracy’s grad student Lee Lemenager will be manning the endoscope. Lee has the kind of face that children draw when they first begin to draw faces, everything round and benign. Earlier in the day when he dripped gastric acid on a superworm, it seemed like a friendly thing to do.

  “And this is Frank and Terry, from OMED,” says Tracy as two more men show up in the lab. OMED of Nevada sells used medical equipment. “They lent us tens of thousands of dollars of video equipment that is forty years old and probably worthless. Welcome!” Tracy is one of those supremely likable professors whom students keep in touch with long after graduation. The back wall of the Tracy Laboratory is covered with photographic portraits he has taken of his grad students. His white hair suggests he may be closing in on retirement, but it is difficult to imagine him golfing or watching daytime television.