viper Any of about 200 species (family Viperidae) of venomous snakes in two subfamilies: Viperinae (Old World vipers of Europe, Asia, and Africa) and Crotalinae (pit vipers). Two long, hollow, venom-injecting fangs attached to the movable bones of the viper’s upper jaw can be folded back in the mouth when not in use. Vipers range in length from less than 12 in. (30 cm) to more than 10 ft (3 m). They eat small animals and hunt by striking, then trailing, their prey. Many Old World vipers are terres¬ trial; a few are arboreal or burrowers. Most bear live young.
Viracocha \,be-ra-'ko-cha\ Creator god of the pre-Inca inhabitants of Peru, later assimilated into the Inca pantheon. A god of rain, he was believed to have created the Sun on the waters and foam of Lake Titicaca. After forming the rest of the heavens and the earth, he wandered through the world teaching humankind the arts of civilization. At Manta (Ecua¬ dor) he walked westward across the Pacific Ocean, promising to return one day. His cult was extremely ancient, and he is probably the weeping god sculpted in the megalithic ruins at Tiwanaku.
viral VvI-rolX diseases Diseases caused by viRUses. Long-term immunity usually follows viral childhood diseases (see chickenpox). The common cold recurs into adulthood because many different viruses cause its symp¬ toms, and immunity against one does not protect against others. Some viruses mutate fast enough to reinfect people after recovery (see influ¬ enza) or to keep the immune system from fighting them off (see AIDS). Cer¬ tain cancers are caused by viruses. Vaccines can prevent some viral diseases. Most recently developed antiviral drugs work only against spe¬ cific viruses; antibiotics are ineffective against viral diseases. See also poliomyelitis; smallpox.
Virchow \'fir-ko\, Rudolf (Carl) (b. Oct. 13, 1821, Schivelbein, Pomerania, Prussia—d. Sept. 5, 1902, Berlin) German pathologist, anthropologist, and statesman. In 1847 he cofounded the pathology jour¬ nal now named for him (Virchows Archiv). He held the first chairs of pathological anatomy at the Universities of Wurzburg (1849-56) and Ber¬ lin (1856-1902). In 1861 he was elected to the Prussian Diet and founded the Progressive Party. He coined the terms thrombosis and embolism while disproving the theory that phlebitis causes most diseases. His work sup¬ ported emerging ideas on cell division and metabolism, pointing out that cell division accounted for the multiplication of cells to form tissues. His rejection of the theory that bacteria cause disease and of Ignaz Semmel- weis’s advocacy of antisepsis delayed the use of antiseptics. Virchow also founded two anthropological societies and accompanied Heinrich Schlie- mann to Troy (1879) and Egypt (1888).
vireo Vvir-e-,o\ Any of 42 species (family Vireonidae) of New World songbirds with a stout, slightly notched, hook-tipped bill that has fine bristles at the base. Vireos are 4-7 in. (10-18 cm) long and are plain gray or greenish, with white or yellow touches. They glean insects from foli¬ age in woodlands and thickets, repeating loud short phrases over and over. The nest is a cuplike structure suspended from a small fork in a branch. The red-eyed vireo (Vireo olivaceus), which breeds from southern Canada to Argentina, is 6 in. (15 cm) long and has a black-outlined, white eye stripe that contrasts with its gray crown.
Virgil or Vergil Wor-jil\ orig. Publius Vergilius Maro (b. Oct. 15, 70, Andes, near Mantua—d. Sept. 21, 19 bc, Brundisium) Greatest of Roman poets. The well-educated son of a prosperous provincial farmer, Virgil led a quiet life, though he eventually became a member of the circle around Octavian (later Caesar Augustus) and was patronized by Maece¬ nas. His first major work, the 10 pastoral Eclogues (42-37), may be read as a prophecy of tranquility, and one has even been read as a prophecy of Christianity. The Georgies (37-30) point toward a Golden Age in the form of practical goals: the repopulation of rural lands and the rehabili¬ tation of agriculture. His great epic, the Aeneid (begun c. 29, but unfin¬ ished at his death), is one of the masterpieces of world literature. A celebration of the founding of Rome by the legendary Aeneas at the request of Augustus, whose consolidation of power in 31-30 unified the Roman world, it also explores the themes of war and the pathos of unre¬ quited love. In later centuries his works were regarded in the Roman Empire as virtually sacred. He was taken up reverently by Christians as well, including Dante, who, in his poem The Divine Comedy, made Vir¬ gil his guide through hell and purgatory.
Virgin Birth Fundamental doctrine of orthodox Christianity that Jesus had no natural father but was conceived by Mary through the power of the Holy Spirit. Based on the infancy narratives in the Gospels of Matthew and Luke, the doctrine was universally accepted in the Christian church by the 2nd century. It remains a basic article of belief in Roman Catholi¬ cism, Eastern Orthodoxy, most Protestant churches, and Islam. A corol¬ lary of its dogma is the doctrine of Mary’s perpetual virginity, accepted by the Orthodox and Roman Catholic churches and by some Lutheran and Anglican theologians. See also Immaculate Conception.
Virgin Islands, British British overseas territory (pop., 2005 est.: 27,200), West Indies. Part of the Virgin Islands chain, it consists of the islands of Tortola, Anegada, Virgin Gorda, and Jost Van Dyke and 32 smaller, mostly uninhabited islands. The chief town and port is Road Town on Tortola. The majority of British Virgin Islanders are of African or African-European descent. English is the chief language. Religion: Christianity (predominantly Protestant). The islands are generally hilly, and many have lagoons with coral reefs and barrier beaches. Tourism is the mainstay of the economy. The Virgin Islands probably were originally settled by Arawak Indians but were inhabited by Caribs by the time Chris¬ topher Columbus visited in 1493. The islands were a haunt for pirates, and Tortola was held by Dutch buccaneers until it was taken by English plant¬ ers in 1666; it was annexed by the British-administered Leeward Islands in 1672. The British sugar plantations declined after slavery was abol¬ ished in the 19th century. The islands were part of the Colony of the Lee¬ ward Islands from 1872 until 1956, when the British Virgin Islands became a separate colony. Its status was changed to an overseas territory in 2002.
Virgin Islands National Park Conservation area, St. John, U.S. Virgin Islands. Covering 14,696 acres (5,947 hectares), it has steep moun¬ tains, white beaches, and coral reefs. Though most of the tree cover was removed for sugarcane cultivation in the 17th—18th century, the land has reverted to forest. Some 100 species of birds and the only native land mammal, the bat, can be found there. It has remains of Arawak Indian villages.
Virgin Islands of the U.S. Unincorporated U.S. island territory (pop., 2005 est.: 108,700), West Indies. Part of the Virgin Islands chain, it consists of the islands of Saint Croix, Saint John, and Saint Thomas and about 50 small islets. Area: 136 sq mi (352 sq km). Capitaclass="underline" Charlotte Amalie. The great majority of the population is of African descent; most of the remainder are Hispanic (mainly Puerto Rican) or recent immigrants from the U.S. The people are U.S. citizens and elect a nonvoting repre¬ sentative to the U.S. House of Representatives, but they do not vote in U.S. national elections. Languages: English (official), French, Spanish. Religion: Christianity (mainly Protestant; also Roman Catholic, other Christians). The islands are hilly and surrounded by coral reefs. Tourism dominates the economy. The islands probably were originally settled by Arawak Indians but were inhabited by the Caribs by the time Christopher Columbus landed on St. Croix in 1493. St. Croix was occupied by the Dutch, English, French, and Spanish and at one time was owned by the Knights of Malta. Denmark occupied St. Thomas, St. John, and St. Croix and established them as a Danish colony in 1754. The U.S. purchased the Danish West Indies in 1917 for $25 million and changed the name to the Virgin Islands. They were adminis¬ tered by the U.S. Department of the Interior from 1931. In 1954 the Organic Act of the Virgin Islands created the current governmental structure, and in 1970 the first popu¬ larly elected governor took office.