touch-me-not Either of two North American impatiens, also known as jewelweed or snapweed, growing in moist areas. Impatiens capensis, also called I. biflora, typically has crimson-spotted orange flow¬ ers; I. pallida has yellow to white flowers, sometimes spotted with brownish-red. They are common weeds native to extensive regions of eastern North America. Their juice is said to be a remedy for poison-ivy rashes.
touch reception See mechanoreception
touchstone Black, silica-containing stone used in assaying to determine the purity of gold and silver. The metal to be assayed is rubbed on the touchstone, and then a sample of metal of known purity is rubbed on the stone right next to it. The streaks of metal on the stone are treated with nitric acid, which dissolves impurities, thus increasing the contrast between the two samples when compared. Because other metals, such as copper, can be alloyed to silver without changing its colour significantly, the touchstone method is not usually used now to assay silver, though it is still used to assay gold and provides a reasonably accurate guide to quality.
Toulon \tii-'lo n . Siege of (Aug. 28-Dec. 19, 1793) Military engage¬ ment in the French Revolutionary Wars. French royalists handed over the naval base and arsenal at Toulon, France, to an Anglo-Spanish fleet in August. The French Revolutionary army began a siege to recapture the port city and, after months of preparations, successfully assaulted the allied-held forts commanding the anchorage. A battery of French guns, commanded by the young Napoleon Bonaparte, fired on the British fleet and forced it to evacuate the inner harbour, though British and Spanish troops blew up the arsenal and burned 42 French ships before leaving. For his key role in the victory, Napoleon was promoted to brigadier gen¬ eral.
Toulouse \tii-'luz\ ancient Tolosa City (pop., 2004 est.: 426,700), on the Garonne River in southern France. Founded in ancient times, it was taken from its Celtic inhabitants by the Romans in the 1st century bc. After ad 778 it became the seat of the feudal countship of Toulouse. Prot¬ estants were massacred there during the 16th-century Wars of Religion. In 1814 it was the scene of the British victory over the French in the last battle of the Peninsular War. A rail junction and canal port, Toulouse is a centre of the French aviation industry. It has many historic buildings, including a Gothic cathedral and a Romanesque basilica, and the tomb of St. Thomas Aquinas. The university, founded in 1229, is one of the oldest in the world.
Toulouse-Lautrec \tu-Tuz-lo-'trek\ (-Monfa), Henri (-Marie- Raymond) de (b. Nov. 24, 1864, Albi, France—d. Sept. 9, 1901, Mal- rome) French painter and graphic artist. Born to an old aristocratic family, he developed his interest in art during lengthy convalescence after both his legs were fractured in separate accidents (1878, 1879) that left them permanently stunted and made walking difficult. In 1881 he resolved to become an artist; after taking instruction, he established a studio in the Montmartre district of Paris in 1884 and began his lifelong association with the area’s cafes, cabarets, entertainers, and artists. He captured the effect of the movement of dancers, circus performers, and other enter¬ tainers by simplifying outlines and juxtaposing intense colours; the result was an art throbbing with life and energy. His lithographs were among his most powerful works, and his memorable posters helped define the
Gray-breasted mountain toucan (Andi- gena hypoglauca).
PAINTING BY JOHN P. O'NEILL
© 2006 Encyclopaedia Britannica, Inc.
Toungoo dynasty ► Tower I 1927
possibilities of the genre. His pieces are often sharply satirical, but he was also capable of great sympathy, seen most poignantly in his studies of prostitutes (e.g.. At the Salon, 1896). His extraordinary style helped set the course of avant-garde art for decades to come. A heavy drinker, he died at 36.
Toungoo Vtauq-.giA dynasty Ruling house in Myanmar (Burma) from the 15th or 16th century to the 18th century. The founder of the empire is considered to be either King Minkyinyo (r. 1486-1531) or his son Tab- inshwehti (r. 1531-50), who expanded the empire and welded it together. Tabinshwehti’s brother-in-law Bayinnaung (r. 1551-81) extended the dynasty’s reach to include much of Laos and Siam (Thailand). No ruler ever managed to conquer Arakan (in southern Myanmar), though Tabin- shwehti, Bayinnaung, and others tried. The empire slowly disintegrated after Bayinnaung’s death, but the dynasty continued until 1752.
Tour, Georges de La See Georges de La Tour
Tour de France \,tur-d3-'fra n s\ World’s most prestigious and difficult bicycle race. Staged for three weeks each July—usually in some 20 day¬ long stages—the Tour typically comprises 20 professional teams of nine riders each and covers some 3,600 km (2,235 miles) of flat and moun¬ tainous country, mainly in France, with occasional and brief visits to Bel¬ gium, Italy, Germany, and Spain. Each stage of the race is timed, and the rider with the lowest aggregate time for all stages is the winner. Estab¬ lished in 1903 by Henri Desgrange (b. 1865—d. 1940), a French cyclist and journalist, the race has been run every year except during the world wars.
Touraine \tli-'ren\ Historical region, northwestern central France. It encompassed the former province of Touraine; its capital was at Tours. In Roman times it was inhabited by the Gallic Turones. In the 5th century ad it was incorporated in the Visigothic kingdom, and it passed to the Franks in 507. Contested by various powers over the succeeding centu¬ ries, it came under French influence in the early 13th century. It began to decline c. 1700, and the province was abolished in 1789 during the French Revolution. The region, which includes the Loire River valley, known for its magnificent chateaus, is sometimes called the Garden of France.
Toure \tii-'ra\, (Ahmed) Sekou (b. Jan. 9, 1922, Faranah, French Guinea—d. March 26, 1984, Cleveland, Ohio, U.S.) First president of Guinea (1958-84) and a leading African politician. Toure, who claimed to be descended from Samory, helped lead Guinea’s campaign for inde¬ pendence in 1958. He actively supported Kwame Nkrumah’s program for African unity and gave Nkrumah asylum when he was deposed in 1966. A member of the (Organization of African Unity (now African Union), he was viewed internationally as a moderate Islamic leader. After an unsuc¬ cessful invasion from neighbouring Portuguese Guinea (now Guinea- Bissau) in 1971, he imposed harsh domestic measures and ruled with an iron hand.
Tourette \tu-'ret\ syndrome Rare neurological disease that causes repetitive motor and vocal tics. Named for Georges Gilles de la Tourette, who first described it in 1885, it occurs worldwide, is usually inherited, generally begins at ages 2-15, and is three times more common in males. Motor tics occur first in about 80% of cases, compulsions to utter abnor¬ mal sounds in the rest. A compulsion to utter obscenities, once thought characteristic, is often absent. Repetition of words heard and spontaneous repetition of one’s own words are two distinctive symptoms. Other vocal tics may include meaningless sounds. Motor tics may be virtually unno- ticeable; more complex ones may appear intentional (e.g., hopping, clap¬ ping). Sleep, intense concentration, and exertion tend to suppress the tics; emotional stress worsens them. Unlike psychiatric compulsive disorders, Tourette syndrome has a neurological origin and may improve with psy¬ chogenic drugs. Brain neurotransmitter abnormalities may be involved, but the underlying cause remains uncertain.
tourmaline Vtor-mo-lon, 'tor-mo-.lenV Complex silicate mineral that is often used as a gemstone. Three types of tourmaline, distinguished by the presence of certain elements, are usually recognized: iron tourmaline (schorl) is black, magnesium tourmaline (dravite) is brown, and alkali tourmalines may be pink, green, blue, or colourless. Tourmaline is most common in granite pegmatites. Gem-quality stones are found especially in the U.S., Brazil, Russia, and Madagascar.