Off the table and into the boWhat the stomach doesThe man with a rid on his stomachWhy you need a fiverCapturing the most important ingredient: waterA colony of busy, benign bacteriaTo the rescue: new drugs, new instrumentsImagine the discomfort of poor Mr. Polly. The rotund hero ofa 1909 comic romance by the English novelist H. G. Wells,he was a compulsive trencherman. At one memorable sitting,Mr. Polly managed to work through a heaping platter of coldpork, a dish of cold potatoes mixed with pickles, onions,cauliflower and capers, a cold suet pudding with treacle,along with hard cheese and several slabs of leaden, grayishbread--the whole washed down with a mighty jugful ofbeer. This huge repast, said Wells, caused "wonderfulthings" to occur in Mr. P611y's body. "It must have been likea badly managed industrial city during a period of depres-sion," Wells wrote, "agitators, acts of violence, strikes, theforces of law and order doing their best, rushings to and fro,upheavals, the Marseillaise, tumbrils, the rumble and thethunder of the tumbrils." Mr. Polly survived the tumult, and so do most people whoindulge themselves, however extravagant the menu. Theability of human beings to cope with the most outrageousdemands of appetite is wonderful indeed. Homo sapiens isomnivorous. Unlike the cow munching its cud, or the hum-mingbird sipping nectar, people can eat almost anything, andcommonly do--grains, roots, leaves, berries, fish, meat andmilk, all containing complex mixtures of potential nutrients.Only such woody fare as grass stems and tree bark are trulyinedible: The human system lacks the chemicals needed to O/O 000110~0 ln(~ ([~ffreg~u{ar"l'y" consume~ anff conve~(~ in oenergy~~~raIt ana~Od within the body. The first stage in this conversion is diges-tion. Each mouthful of food must be pulverized, dissolved oremulsified, and broken down chemically into submicro- scopic units that can be taken into the bloodstream. As food makes its way down the gullet, or esophagus, andthrough the 30-foot length of the alimentary canal, it ischurned and bombarded with a well-timed sequence ofagents that change it into one form after another--usually forgood purpose, sometimes for ill. Glands in the mouth pour insaliva; cells in the linings of the stomach and intestines addpotent digestive juices. Two of the body's largest organs, theliver and pancreas, add other essential secretions. Then,when the nutrients have been extracted and absorbed into theblood for distribution throughout the body, the residue isexpelled. The process goes on, day in and day out, year afteryear, for a lifetime, with very little conscious effort. For all its complexity, it is astonishing how smoothly theprocess goes--usually. But every now and again somethinggoes awry, and the results are never pleasant. Under theimpact of foods that are too rich or exotic, or of meals takentoo fast or too gluttonously, the system rebels. Any numberof viruses or bacteria--some ordinarily friendly--can at-tack the gut to bring sudden misery. A quarrel or a bad day atwork can cause upset: No system of the body is so immedi-ately sensitive to emotional stress as the digestive tract.In this 19th Century Japanese woodcut, tiny figures illustrate an old Oriental theory of digestion: Food moved from the stomach(above the brownish intestines), to the mixing vat of the liver, the fiery caldron of the spleen, and the heart, "Lord of Entrails."