Steinway-Welte player piano, 1910; in the British Piano and Musical Museum, Brentford, Middlesex, Eng.
COURTESY OF THE BRITISH PIANO AND MUSICAL MUSEUM, BRENTFORD, MIDDLESEX, ENG.
© 2006 Encyclopaedia Britannica, Inc.
Plessy v. Ferguson ► plover I 1513
became a leader of the Land and Freedom group (1877-80). To avoid arrest, he went into a long exile in Geneva (1880-1917). In 1883 he founded the first Russian Marxian revolutionary organization, Liberation of Labour, which became the Russian Social-Democratic Workers' Party (1898). In Socialism and Political Struggle (1883) and Our Differences (1885), he described a two-phase revolutionary scheme that influenced Russian Marxist thought. Followers in the 1890s included Vladimir Ilich Lenin. After the party split (1903), Plekhanov joined the Mensheviks but spent years trying to reunite the party. He supported the Allies in World War I and opposed the Bolshevik seizure of power. After returning briefly to Russia in 1917, he died in exile in Finland.
Plessy v. Ferguson (1896) U.S. Supreme Court decision that estab¬ lished the legality of racial segregation so long as facilities were “sepa¬ rate but equal.” The case involved a challenge to Louisiana laws requiring separate railcars for African Americans and whites. Though the laws were upheld by a majority of 8 to 1, a famous dissent by John Marshall Har¬ lan advanced the idea that the U.S. Constitution is “color-blind.” The Plessy decision was overturned in 1954 by Brown v. Board of Education.
Pleven \pla-‘ven\, Rene (b. April 13 or 15, 1901, Rennes, France—d. Jan. 13, 1993, Paris) French politician and premier (1950-51, 1951-52). A lawyer and industrial executive, he served in Charles de Gaulle’s war¬ time government (1940-45). Elected to the National Assembly in 1945, he cofounded with Francois Mitterrand the Democratic and Socialist Union of the Resistance, serving as its president (1946-53). He held sev¬ eral postwar cabinet posts, including minister of defense (1949-50, 1952— 54). He sponsored the Pleven Plan for a unified European army, but the European Defense Community, based on his plan, collapsed in 1954. He served as minister of justice (1969-73).
Plexiglas See Lucite
Pleyel \ple-'yel,\ English VplI-oL, Ignace Joseph or Ignaz Josef Pleyel (b. June 18, 1757, Ruppersthal, Austria—d. Nov. 14, 1831, Paris, France) Austrian-French music publisher, piano maker, and composer. He studied with Joseph Haydn (c. 1772-77), then held posts in Vienna and Strasbourg and traveled in Italy before settling in Paris. His publishing house, Maison Pleyel, published Haydn’s complete string quartets (1801), and in 1802 it published the first miniature scores for study. It ceased publishing in 1834, but the piano-manufacturing company he founded in 1807 lasted until the 1960s. Pleyel’s music, including 45 symphonies and more than 70 string quartets, was once very popular.
Plimsoll Vplim-solV Samuel (b. Feb. 10, 1824, Bristol, Gloucester¬ shire, Eng.—d. June 3,1898, Folkestone, Kent) British reformer. A London coal merchant, he served in Parliament (1868-80). With his book Our Sea¬ men (1873), he helped overcome resistance to the Merchant Shipping Act, which instituted such reforms as the loading limit for cargo ships. A load line (the Plimsoll mark or line) was marked on the hull of every cargo ship, indicating the maximum depth to which the ship could be safely loaded.
Pliny Vplin-e\ the Elder Latin Gaius Plinius Secundus (b. ad 23,
Novum Comum, Transpadane Gaul—d. Aug. 24, 79, Stabiae, near Mt. Vesuvius) Roman scholar. Descended from a prosperous family, Pliny pursued a military career, held official positions (including procurator of Spain), and later spent years in semiretirement, studying and writing. His fame rests on his Natural History (ad 77), an encyclopaedic work of uneven accuracy that was the European authority on scientific matters up to the Middle Ages. Six other works ascribed to him were probably lost in antiquity. He died while observing the great eruption of Vesuvius.
Pliny the Younger Latin Gaius Plinius Caecilius Secundus (b.
ad 61/62, Comum—d. c. 113, Bithynia, Asia Minor) Roman author and administrator. The nephew of Puny the Elder, he practiced law and held official posts, including consul and head of the military and senatorial treasuries. He is known for the nine books of private letters he published in ad 100-109. The carefully composed letter, at that time a fashion among the wealthy, was transformed by Pliny into an art. His are charming and meticulous occasional pieces on diverse literary, social, and domestic themes that intimately illustrate public and private life in the heyday of the Roman Empire.
Pliocene \'pli-3-,sen\ Epoch Last and shortest epoch of the Tertiary Period, from c. 5.3 to c. 1.8 million years ago. It follows the Miocene Epoch and precedes the Pleistocene Epoch of the Quaternary Period. Pliocene environments were generally cooler and drier than those of preceding Tertiary epochs. In general, Pliocene mammals grew larger than those of
earlier epochs. The more advanced primates continued to evolve, and it is possible that the australopithecines (see Australopithecus), the first crea¬ tures that can be termed human, developed late in the Pliocene.
Plisetskaya Vpli-'set-sko-yoV Maya (Mikhaylovna) (b. Nov. 20, 1925, Moscow, Russia, U.S.S.R.) Russian prima ballerina. She studied at the Bolshoi Ballet’s school in Moscow and joined the company as a solo¬ ist in 1943. Noted for her technical virtuosity and ability to integrate act¬ ing with dancing, she toured worldwide with the Bolshoi Ballet and appeared as a guest artist with several companies, including the Paris Opera. She also danced in several films, including Swan Lake (1957). In the 1980s she was a guest ballet director in Rome and then in Madrid.
Maya Plisetskaya in Swan Lake, 1961.
PARIS MATCH-PICTORIAL PARADE
PLO See Palestine Liberation Organization
ploidy \'ploi-de\ Number of sets of chromosomes in the nucleus of a cell. In normal human body cells, chromosomes exist in pairs, a condition called diploidy. During meiosis the cell produces sex cells (gametes), each containing half the normal number of chromosomes, a condition called haploidy. When an egg and a sperm unite in fertilization, the diploid con¬ dition is restored. Polyploid cells have three or more times the number of chromosomes found in haploid cells; polyploid organisms usually can¬ not reproduce. Aneuploid cells have an abnormal number of chromosomes that is not a multiple of the haploid number. Aneuploidy is most often caused by an error leading to an unequal distribution of chromosomes during division.
Plotinus \plo-'tI-n9s\ (b. ad 205, Lyco, or Lycopolis, Egypt?—d. 270, Campania) Egyptian-Roman philosopher. At age 27 he traveled to Alex¬ andria, where he studied philosophy for 11 years. In about 242 he joined the expedition of the Roman emperor Gordian III against Persia in order to learn about the philosophies of the Persians and Indians. He went to Antioch and then to Rome, where he settled at age 40, becoming the cen¬ tre of an influential circle of intellectuals. His attempt to form a Platonic republic in Campania c. 265 was halted by the emperor Galuenus. He was the founder of the school of philosophy known as Neoplatonism; his col¬ lected works, the Enneads (from Greek, enneas: “set of nine”), arranged by his disciple Porphyry (232?-c. 305), are the first and greatest collec¬ tion of Neoplatonic writings. For Plotinus, philosophy was not only a matter of abstract speculation but also a way of life and a religion. His works strongly influenced early Christian theology, and his philosophy was widely studied and emulated for many centuries.
Plovdiv \'pl6v-,dif\ City (pop., 2001: 340,638), south-central Bulgaria. It is situated on the Maritsa River, north of the Rhodope Mountains. In 341 bc it fell to Philip II and was renamed Philippopolis. From ad 46 it was called Trimontium and was the capital of the Roman province of Thrace. It changed hands repeatedly during the Middle Ages until 1364, when it was captured by the Turks. After the Russo-Turkish Wars (1877-78), it became the capital of Turkish Eastern Rumelia, which united with Bulgaria in 1885. It officially assumed its present name after World War I. It is a major railroad junction and a food-processing centre with diversified industries.