gall fly: see fruit fly.

gall bladder, small pear-shaped sac that stores and concentrates bile. It is connected to the liver (which produces the bile) by the hepatic duct. When food containing fat reaches the small intestine, the hormone cholecystokinin is produced by cells in the intestinal wall and carried to the gall bladder via the bloodstream. The hormone causes the gall bladder to contract, forcing bile into the common bile duct. A valve, which opens only when food is present in the intestine, allows bile to flow from the common bile duct into the duodenum where it functions in the process of fat digestion. Sometimes the substances contained in bile crystallize in the gall bladder, forming gallstones. These small, hard concretions are more common in persons over 40, especially in women and the obese. They can cause inflammation of the gall bladder, a disorder that produces symptoms similar to those of indigestion, especially after a fatty meal is consumed. If a stone becomes lodged in the bile duct, it produces severe pain. Gallstones may pass out of the body spontaneously; however, serious blockage is treated by removing the gall bladder surgically.

gall, abnormal growth, or hypertrophy, of plant tissue produced by chemical or mechanical (e.g., the rubbing together of two branches) irritants or hormones. Chemical irritants are released by parasitic fungi, bacteria, nematode worms, gall insects, and mites. Crown gall, which attacks peach and other fruit trees, grapes, and roses, is caused by bacteria. Despite its name (the crown is the head of foliage), the tumorous growths usually occur on the stem below ground level. The gall insects (e.g., certain aphids, wasps, moths, beetles, and midges) deposit their eggs in the plant tissues, which begin to swell as the larvae hatch. Sometimes the larvae feed on the gall and pupate within it. The irritant is released by the female at the time of oviposition or by the developing larva itself. Each species of gall insect has its favorite host and forms galls of a characteristic shape; some are large and woody and others may be soft, knobby, or spiny. They may be formed on any part of a plant but generally occur in areas where cells are actively growing. In the United States, Galls are commonly seen on oak and willow trees and on rose bushes, goldenrod, and witch hazel. The Hessian fly, the wheat midge, and the mites and midges that attack fruit trees are the most damaging economically of the gall insects. Galls are rich in resins and tannic acid and have been used in the manufacture of permanent inks and astringent ointments, in dyeing, and in tanning. A high-quality ink has long been made from the Aleppo gall, found on oaks in the Middle East; it is one of a number of galls resembling nuts and called gallnuts or nutgalls.

crown gall: see gall.

Saint Gall, Ger. Sankt Gallen, canton (1993 pop. 432,800), 777 sq mi (2,012 sq km), NE Switzerland. Bordering on Lake Constance in the north and on the Rhine River in the east, it surrounds the entire canton of Appenzell. The south is fairly mountainous, and the north is mainly a meadowland. Wine and fruit are produced. The canton is especially known for its lace embroideries and silk and cotton textiles. Other manufactures include textile machinery, chemicals, pharmaceuticals, pyrotechnics, matches, chocolate, optical goods, felt, and paper. Tourism is also a major industry, with many winter and summer resorts. Its inhabitants are mainly German-speaking. The canton and its capital city, Saint Gall (1993 pop. 72,000), take their name from the Benedictine abbey erected (8th cent.) on the site of the hermitage of St. Gall, an Irish monk, around which the town grew. The abbots of St. Gall, who also ruled Appenzell, became princes of the Holy Roman Empire in the early 13th cent. The town became a free city of the Holy Roman Empire in 1311. Rebelling against the abbot, the city made an alliance with the Swiss Confederation (1454). The Reformation, accepted by the town but suppressed in the districts controlled by the abbot, brought about a long series of disturbances (notably the War of the Toggenburg) until 1718. In 1803 the town and the abbot's domains (secularized in 1798) were consolidated as a canton of the Swiss Confederation under Napoleon's Act of Mediation. One of the oldest scholastic centers north of the Alps, St. Gall has a library with a world-famous collection of medieval manuscripts. An episcopal see since 1846, it also has a noted 18th-century cathedral (formerly the abbey church). There are several museums, schools, and institutes.

Saint Gall, former Benedictine abbey, at St. Gall, Switzerland. Originating in a cell built c.614 by St. Gall, an Irish missionary (see Columban, Saint), it became an abbey under Charles Martel (8th cent.). It gained large landholdings and acquired universal fame as a center of learning in the early Middle Ages. In its library invaluable classic manuscripts were copied and preserved. Among the teachers were Notker Balbulus, Notker Labeo, and four monks named Ekkehard. The abbey was secularized in 1798. The present buildings date mainly from the 18th cent.

Gall, Francis Joseph, 1758-1828, Austrian anatomist and founder of phrenology. He devoted most of his life to a minute study of the nervous system, especially the brain. With the collaboration of a favorite pupil, John Caspar Spurzheim (1776-1832), he incorporated his research into a four-volume work and atlas that appeared from 1810 to 1819. Gall demonstrated that the white matter of the brain consists of nerve fibers, and he launched the doctrine of localization in parts of the brain of various mental processes. Derided for his later involvement with the pseudoscience of phrenology, he left Austria but was received with honors in France and died a wealthy man in Paris. Spurzheim carried the teachings of Gall to England and the United States, also with great success.

Gall, c.1840-1894, war chief of the Sioux, b. South Dakota. He refused to accept the treaty of 1868 (by which he would have been confined to a reservation), joined Sitting Bull and other dissident chiefs, and was the chief military lieutenant of Sitting Bull in the great defeat of George Armstrong Custer in the battle of Little Bighorn in 1876. He retreated to Canada but, after a quarrel with Sitting Bull about returning to their former lands, returned and surrendered at Poplar, Mont. He became a farmer on the reservation and with his friend James McLaughlin, the Indian agent, did much to improve relations between Native Americans and whites.

Muscular membranous sac under the liver that stores and concentrates bile. Pear-shaped and expandable, it holds about 1.7 fluid oz (50 ml). Its inner surface absorbs water and inorganic salts from bile, which becomes 5–18 times more concentrated than when it leaves the liver. The gallbladder contracts to discharge bile through the bile duct into the duodenum. Disorders include gallstones and inflammation (cholecystitis). Surgical removal of the gallbladder (cholecystectomy) has no serious side effects.

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Greenish-yellow liver secretion passed to the gallbladder for concentration, storage, or transport into the duodenum for fat digestion. Bile contains bile acids and salts, cholesterol, and electrolyte chemicals that keep it slightly acidic. In the intestine, products of the acids and salts emulsify fat and reduce its surface tension to prepare it for the action of pancreatic and intestinal fat-splitting enzymes.

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Disease of plants caused by the bacterium Agrobacterium tumefaciens. Thousands of plant species are susceptible, including especially rose, grape, pome and stone fruits (e.g., apples, peaches), shade and nut trees, many shrubs and vines, and perennial garden plants. Symptoms include roundish, rough-surfaced galls, several inches or more in diameter. At first cream-coloured or greenish, they later turn brown or black. As the disease progresses, affected plants lose vigour and may eventually die.

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