parathyroid adenoma, disorder characterized by loss of mineral materials from the skeleton, the development of kidney stones, and occasionally progressive kidney insufficiency. Increase in the number (hyperplasia) of secretory cells of one or more of the parathyroid glands results in an excess of

parathyroid hormone: microscope the PTH-producing cells, called chief cells, isolated from the parathyroid glands, occur in sheets interspersed with areas of fatty tissue. Occasionally the cells are arranged in follicles similar to but smaller than those present in the thyroid gland. As with other protein hormones, PTH is synthesized as a large…

parathyroid gland, endocrine gland occurring in all vertebrate species from amphibia upward, usually located close to and behind the thyroid gland. Humans usually have four parathyroid glands, each composed of closely packed epithelial cells separated by thin fibrous bands and some fat cells. The

parathyroid hormone (PTH), substance produced and secreted by the parathyroid glands that regulates serum calcium concentration. Under the microscope the PTH-producing cells, called chief cells, isolated from the parathyroid glands, occur in sheets interspersed with areas of fatty tissue.

Jacques Cujas: …Cujas specialized in Justinian; his Paratitla, or summaries of Justinian’s Digest and Codex, expresses in short, clear axioms the elementary principles of Roman law. He also edited the Codex Theodosianus. A complete edition of Cujas’s works, in 10 volumes (1658), was prepared by Charles Annibal Fabrot.

D-Day in pictures: …hours before dawn, thousands of paratroopers descended on the Normandy countryside behind the German defenses. At about 6:30 am some 3,000 Allied landing craft began discharging men onto a stretch of beaches between Cherbourg and Le Havre. The Allied plan was to seize a beachhead within range of fighter coverage…

Johne’s disease, serious infectious disease caused by Mycobacterium avium paratuberculosis. Although principally a disease of cattle, it can affect sheep, deer, and goats, and it occurs worldwide. Cows may not show signs of the disease for as long as a year after exposure to it. Chronic diarrhea

taxonomy: Verification and validation by type specimens: Paratypes are specimens used, along with the holotype, in the original designation of a new form; they must be part of the same series (i.e., collected at the same immediate locality and at the same time) as the holotype.

paratyphoid fever, infectious disease caused by any of several organisms: Salmonella paratyphi (paratyphi A), S. schottmuelleri (paratyphi B), or S. hirschfeldii (paratyphi C). S. paratyphi is the cause of paratyphoid fever in humans and is common in areas of Asia, Africa, the Middle East, and

pauraque, (Nyctidromus albicollis), nocturnal bird of brushlands from southern Texas to northern Argentina. It is a relative of the nightjar (q.v.), belonging to the family Caprimulgidae. The pauraque is about 30 cm (about 12 inches) long, with rounded wings and a longish tail. It is mottled brown

lock: Development of modern types.: …most interesting was Robert Newell’s Parautoptic lock, made by the firm of Day and Newell of New York City. Its special feature was that not only did it have two sets of lever tumblers, the first working on the second, but it also incorporated a plate that revolved with the…

Jean Genet: …Blacks), and Les Paravents (1961; The Screens), are large-scale, stylized dramas in the Expressionist manner, designed to shock and implicate an audience by revealing its hypocrisy and complicity. This “Theatre of Hatred” attempts to wrest the maximum dramatic power from a social or political situation without necessarily endorsing the political…

human nervous system: The peripheral nervous system: …these are referred to as paravertebral ganglia. Prevertebral motor ganglia are located near internal organs innervated by their projecting fibers, while terminal ganglia are found on the surfaces or within the walls of the target organs themselves. Motor ganglia have multipolar cell bodies, which have irregular shapes and eccentrically located…

Archaeopteryx: …could be applied to the Paraves, a more inclusive collection of theropod dinosaurs that includes birds and the deinonychosaurs (a group that contains the troodontids and the dromaeosaurs).

El Greco: Middle years: Fray Hortensio Paravicino, the head of the Trinitarian order in Spain and a favorite preacher of Philip II of Spain, dedicated four sonnets to El Greco, one of them recording his own portrait by the artist. Luis de Góngora y Argote, one of the major…

optics: Paraxial, or first-order, imagery: In a lens that has spherical aberration, the various rays from an axial object point will in general intersect the lens axis at different points after emerging into the image space. By tracing several rays entering the lens at different heights…

optics: Paraxial, or first-order, imagery: …close to the axis (a paraxial ray) would intersect the axis, although such a ray could not be traced directly by the ordinary trigonometrical formulas because the angles would be too small for the sine table to be of any use. Because the sine of a small angle is equal…

Chicago: Called the Chicago Transit Authority before shortening its name to that of the city in which it…

animal: Parazoa: a cellular level of organization: Although the two phyla in this subkingdom, Porifera (sponges) and Placozoa, lack clearly defined tissues and organs, their cells specialize and integrate their activities. Their simplicity has been adaptive, and sponges have remained important in benthic marine habitats since…

sponge: Associations with other organisms: , the coral Parazoanthus axinellae grows on the sponge Axinella. The organisms that live in the cavities of sponges include crustaceans, nematode and polychaete worms, ophiuroid echinoderms (brittle stars), and bivalve mollusks; some inhabit a sponge for occasional shelter or nourishment, others establish more intimate associations as parasites…

Pahāṛī, people who constitute about three-fifths the population of Nepal and a majority of the population of neighbouring Himalayan India (in Himachal Pradesh and northern Uttar Pradesh). They speak languages belonging to the Indo-Aryan branch of the Indo-European family. The people are

Péter Nádas: …to the present day, and Párbeszéd: négy nap ezerkilencszáznyolcvankilencben (1992; “Dialogue: Four Days in Nineteen Eighty-nine”), a transcript of a conversation with a Swedish journalist friend about the differences between eastern and western Europe that had come about because of the Iron Curtain. He continued to publish essays and short…

Parbhani, city, east-central Maharashtra state, western India. It lies in an upland plateau region about 10 miles (16 km) south of the Dudna River. The city’s name refers to the Prabhavati Temple, which was forcibly converted to a mosque during the Mughal period. Parbhani is a commercial and

boiling: Parblanching or parboiling consists in immersing the food in cold water and then bringing it slowly to a simmer or boil.

boiling: Parblanching or parboiling consists in immersing the food in cold water and then bringing it slowly to a simmer or boil.

PARC, research company established in 1970 as a division of Xerox Corporation in Palo Alto, California, U.S., to explore new information technologies that were not necessarily related to the company’s core photocopier business. Many innovations in computer design were developed by PARC researchers,

Cameroon: Plant and animal life: Waza National Park in the north, which was originally created for the protection of elephants, giraffes, and antelope, abounds in both forest and savanna animals, including monkeys, baboons, lions, leopards, and birds that range from white and gray pelicans to spotted waders. To the south…

Garamba National Park, large natural area in northeastern Democratic Republic of the Congo, bordering on South Sudan. The park, created in 1938, has an area of 1,900 square miles (4,920 square km) and is a continuation of the South Sudanese savanna fed by the Garamba and Dungu rivers; it was

Gaspesian Provincial Park, park in eastern Quebec province, Canada. The park occupies 500 square miles (1,295 square km) on the Gaspé Peninsula, near the mouth of the St. Lawrence River. It was established in 1937 to protect the fast-diminishing herds of caribou as well as to preserve the natural

Clères Zoological Park, specialty zoo that has one of the world’s finest bird collections. The park was founded in 1919 by Jean Delacour, a widely known aviculturist and ornithologist, on his 26-hectare (65-acre) estate in Clères, Fr. Its bird collection comprises 1,800 specimens representing some

Paris Zoo: …Jardin des Plantes) and the Zoological Park of Paris (Parc Zoologique de Paris), both services of the French National Museum of Natural History.

Jean Racine: Life: …even seduced Molière’s leading actress, Thérèse du Parc, into joining him personally and professionally—and from this point onward all of Racine’s secular tragedies would be presented by the actors of the Hôtel de Bourgogne.

Fate, in Greek and Roman mythology, any of three goddesses who determined human destinies, and in particular the span of a person’s life and his allotment of misery and suffering. Homer speaks of Fate (moira) in the singular as an impersonal power and sometimes makes its functions interchangeable

Fate, in Greek and Roman mythology, any of three goddesses who determined human destinies, and in particular the span of a person’s life and his allotment of misery and suffering. Homer speaks of Fate (moira) in the singular as an impersonal power and sometimes makes its functions interchangeable

postal system: International postal reform: the Universal Postal Union: …such as money orders (1878), parcel post (1885), postal checks (1920), cash on delivery (1947), and savings banks (1957). The UPU has been a specialized agency of the United Nations since 1948.

Bill Parcells is an American professional gridiron football coach and executive who coached the New York Giants of the National Football League (NFL) to Super Bowl victories in 1987 and 1991. Parcells spent most of his childhood in New Jersey, where he acquired the nickname “Bill” from teachers who

Bill Parcells is an American professional gridiron football coach and executive who coached the New York Giants of the National Football League (NFL) to Super Bowl victories in 1987 and 1991. Parcells spent most of his childhood in New Jersey, where he acquired the nickname “Bill” from teachers who

Afghan War: Insurgency against communist rule (1978–92): …People’s (Khalq) Party and the Banner (Parcham) Party, which had earlier emerged from a single organization, the People’s Democratic Party of Afghanistan, and had reunited in an uneasy coalition shortly before the coup. The new government, which had little popular support, forged close ties with the Soviet Union, launched ruthless…

Pachisi, board game that was created in India in about the 4th century CE. Four players in opposing partnerships of two attempt to move pieces around a cross-shaped track. Moves are determined by throws of cowrie shells or dice. Each player has four pieces, which begin at the center space, move

parchment, the processed skins of certain animals—chiefly sheep, goats, and calves—that have been prepared for the purpose of writing on them. The name apparently derives from the ancient Greek city of Pergamum (modern Bergama, Turkey), where parchment is said to have been invented in the 2nd

parchment worm, (genus Chaetopterus), any of several species of segmented worms of the class Polychaeta (phylum Annelida), especially C. variopedatus of the Atlantic and Pacific oceans. They live on the sea bottom in U-shaped tubes that are lined with parchmentlike material. Parchment worms grow to

cockroach: Family Ectobiidae: The Pennsylvania wood cockroach (Parcoblatta pennsylvanica) is found under logs and stones in northern latitudes. The male and female are so different in appearance that they were once considered separate species. The male, 15 to 25 mm (0.6 to 1 inch) long, has wings that extend…

leopard, (Panthera pardus), large cat closely related to the lion, tiger, and jaguar. The name leopard was originally given to the cat now called cheetah—the so-called hunting leopard—which was once thought to be a cross between the lion and the pard. The term pard was eventually replaced by the

purdah, practice that was inaugurated by Muslims and later adopted by various Hindus, especially in India, and that involves the seclusion of women from public observation by means of concealing clothing (including the veil) and by the use of high-walled enclosures, screens, and curtains within the

Jafar Panahi: Taxi, It Was Just an Accident, and legal issues: …but nevertheless made Pardah (2013; Closed Curtain), directed with Kambuzia Partovi. A screenwriter (Partovi) goes into seclusion at his seaside home, but his solitude is disturbed by a young woman fleeing the police. As in The Mirror, the story is broken by real life, when Panahi appears as himself, and…

purdah, practice that was inaugurated by Muslims and later adopted by various Hindus, especially in India, and that involves the seclusion of women from public observation by means of concealing clothing (including the veil) and by the use of high-walled enclosures, screens, and curtains within the

pardalote, (genus Pardalotus), any of four species of Australian songbirds of the family Pardalotidae (order Passeriformes), with a simple tongue and a thickish, unserrated bill. Three of the four species have gemlike white spangles on the dark upper parts (the striated pardalote [Pardalotus

passeriform: Annotated classification: Family Pardalotidae (pardalotes and bristlebirds) Small to medium-sized songbirds, 9–27 cm (3.5–11 inches). Pardalotes once allied to the similar flowerpeckers (Dicaeidae), but DNA studies revealed that they were relicts of old radiation of Australian songbirds. Plumage ranges from colourful to sombre brown. Bills stubby (pardalotes) or…

pardalote, (genus Pardalotus), any of four species of Australian songbirds of the family Pardalotidae (order Passeriformes), with a simple tongue and a thickish, unserrated bill. Three of the four species have gemlike white spangles on the dark upper parts (the striated pardalote [Pardalotus

pardalote: The spotted pardalote (P. punctatus), with a yellow throat and rump, digs tunnels in sandbanks or in level ground.

Iberian lynx, (species Lynx pardinus), medium-sized wild cat endemic to the Iberian Peninsula in southwestern Europe. It is among the rarest cats in the world. The International Union for Conservation of Nature (IUCN) classified the Iberian lynx as critically endangered in the early 2000s, but its

Mattancherry: …notable chiefly for the impressive Pardesi synagogue of the Jewish community as well as for the palace of the rajas of Kochi.

African American literature: Drama and poetry: poet laureate 2017–19), Gregory Pardlo, Tyehimba Jess, and Jericho Brown. In addition, Elizabeth Alexander and Amanda Gorman joined the small number of poets, which have included Robert Frost and Maya Angelou, who were invited to read at a

pardo, In Venezuela, a person of mixed African, European, and Indian ancestry. In the colonial period, pardos, like all nonwhites, were kept in a state of servitude, with no hope of gaining wealth or political power. Nevertheless, most pardos remained royalists during much of the war for

Emilia, condesa de Pardo Bazán was a Spanish author of novels, short stories, and literary criticism. Pardo Bazán attained early eminence with her polemical essay “La cuestión palpitante” (1883; “The Critical Issue”). It discussed Émile Zola and naturalism, made French and Russian literary

Civilista: José Pardo y Barreda, an able Civilista president, served two terms (1904–08 and 1915–19); he led efforts to enact labour-reform laws, moved forcefully to improve primary education, and oversaw fiscal reforms directed by the treasury minister Augusto B. Leguía y Salcedo, who followed Pardo as…

Claudia Sheinbaum is a Mexican politician and environmental engineer who is the President of Mexico. She is the first woman and the first Jewish person to be elected to the post. Sheinbaum previously served as mayor of Mexico City (2018–23) before stepping down to run in the presidential election

Jeopardy!: Jeopardy! hosts: …the day on NBC, with Don Pardo as announcer, and eventually went into syndication; it aired in various formats until 1979. The show relaunched in 1984 (considered the first season of the modern version of the show) with Canadian broadcaster Alex Trebek, who hosted until his death in 2020. Johnny…

Jeopardy!: Jeopardy! hosts: …the day on NBC, with Don Pardo as announcer, and eventually went into syndication; it aired in various formats until 1979. The show relaunched in 1984 (considered the first season of the modern version of the show) with Canadian broadcaster Alex Trebek, who hosted until his death in 2020. Johnny…

Civilista: …was founded in 1871 by Manuel Pardo to oppose the corrupt military regime of President José Balta (served 1868–72). Pardo was elected president in May 1872, taking office that summer after a military coup to block his accession failed.

Antonio Cánovas del Castillo: …Alfonso XIII by the so-called Pact of Pardo with Sagasta and Martínez Campos and by his own resignation as prime minister.

marbled cat, (species Felis marmorata), rare Southeast Asian cat, family Felidae, often referred to as a miniature version of the unrelated clouded leopard. The marbled cat is about the size of a domestic cat; it measures roughly 45–60 cm (18–24 inches) long, excluding a tail of approximately the

pardon, in law, release from guilt or remission of punishment. In criminal law the power of pardon is generally exercised by the chief executive officer of the state. Pardons may also be granted by a legislative body, often through an act of indemnity, anticipatory or retrospective, for things done

The Pardoner’s Tale, one of the 24 stories in The Canterbury Tales by Geoffrey Chaucer. The cynical Pardoner explains in a witty prologue that he sells indulgences—ecclesiastical pardons of sins—and admits that he preaches against avarice although he practices it himself. His tale relates how three

wolf spider: Major genera and species: Thin-legged wolf spiders (Pardosa), which have a lens-shaped greenish or gray egg sac, have relatively long legs with long spines on the “foot.” Burrowing wolf spiders (Geolycosa), which spend most of their lives in burrows, have heavy front legs that are used for digging.

Pardubice, city, north-central Czech Republic, at the confluence of the Labe and Chrudimka rivers, east of Prague. Originating in the 13th century as a trade mart, it received civil rights in 1340 and by 1490 had become a possession of the Czech Pernštejn family, who renovated it in Renaissance

Pardubice, city, north-central Czech Republic, at the confluence of the Labe and Chrudimka rivers, east of Prague. Originating in the 13th century as a trade mart, it received civil rights in 1340 and by 1490 had become a possession of the Czech Pernštejn family, who renovated it in Renaissance

leopard, (Panthera pardus), large cat closely related to the lion, tiger, and jaguar. The name leopard was originally given to the cat now called cheetah—the so-called hunting leopard—which was once thought to be a cross between the lion and the pard. The term pard was eventually replaced by the

Ambroise Paré was a French physician, one of the most notable surgeons of the European Renaissance, regarded by some medical historians as the father of modern surgery. About 1533 Paré went to Paris, where he soon became a barber-surgeon apprentice at the Hôtel-Dieu. He was taught anatomy and

Parecis Mountains, mountains, Rondônia and Mato Grosso estados (“states”), west-central Brazil. Rising out of the tropical rain forests of Rondônia, near the Bolivian border, the range extends southeastward for 500 miles (800 km) to the vicinity of Diamantino in Mato Grosso. Its northwestern

Angel Falls, waterfall in the Guiana Highlands in Bolívar state, southeastern Venezuela, on the Churún River, a tributary of the Caroní, 160 miles (260 km) southeast of Ciudad Bolívar. The highest waterfall in the world, the cataract drops 3,212 feet (979 metres) and is 500 feet (150 metres) wide

Mexico: The age of Santa Anna: Texas and the Mexican-American War: …the government of Mexican president Mariano Paredes y Arrillaga was overthrown, and Santa Anna reemerged as president in September 1846. Almost immediately, Santa Anna mobilized Mexican forces and marched northward, boasting that the superior numbers and courage of his men meant that he would sign a peace treaty in Washington.…

paregoric, preparation principally used in the treatment of diarrhea. Paregoric, which decreases movement of the stomach and intestinal muscles, is made from opium tincture (laudanum) or from powdered opium and includes anise oil, camphor, benzoic acid, glycerin, and diluted alcohol. The usual

Bradysaurus: …larger group of reptiles called pareiasaurs, which were characterized by massive bodies, strong limbs and limb supports, and grotesque skulls with many bony protuberances. Pareiasaurs were not dinosaurs, but they were the first very large land vertebrates and were unusual for their time in that they were herbivorous. Bradysaurus, like…

apophenia: Forms of apophenia: In pareidolia, illusory perception is visual, and thus individuals tend to see familiar patterns, such as faces or objects, in random stimuli; for example, a person may see images of animals or figures in clouds or rock formations. Gambler’s fallacy is the erroneous belief that an…

reptile: Annotated classification: †Order Pareisauria (pareisaurs) Middle to Upper Permian. Two or 3 families, 10 or more genera. Small to moderately large (2 metres [about 7 feet]), terrestrial reptiles; appearance from lizardlike to sprawl-limbed and cowlike. Dermal sculpturing of large tuberosities and deep pits on skull; limbs well developed;…

Juan de Pareja was a Spanish painter and student of Diego Velázquez. Pareja initially assisted Velázquez in his studio as an enslaved person. Pareja accompanied Velázquez on his second visit to Italy (1649–51), where Velázquez painted Pareja’s portrait. The portrait was purchased at auction by the

Western painting: International Gothic: …of the master of the Parement de Narbonne (1370s), an altar hanging (parement) found at the Cathedral of St. Justin Narbonne. These artists, who were active from about 1370 to 1410, worked in a very distinctive style: their figures, while graceful, have markedly heavy heads and expressive faces. That some…

respiratory disease: Morphological classification of respiratory disease: …capillary bed that constitutes the parenchyma, or the essential tissue of the lung itself. The parenchyma is the gas-exchanging tissue of the lung and has a surface area roughly comparable to that of a tennis court. Blood is distributed to the lung through the branching pulmonary artery, which subdivides with…

parenchyma, in plants, tissue typically composed of living cells that are thin-walled, unspecialized in structure, and therefore adaptable, with differentiation, to various functions. The cells are found in many places throughout plant bodies and, given that they are alive, are actively involved in

angiosperm: Ground tissue: …composed of relatively simple, undifferentiated parenchyma cells. In most plants, metabolic activity (such as respiration, digestion, and photosynthesis) occurs in these cells because they, unlike many of the other types of cells in the plant body, retain their protoplasts (the cytoplasm, nucleus, and cell organelles) that carry out these functions.

sponge: Sexual reproduction: …the Demospongiae is called a parenchymella; it is solid and compact, with an outer layer of flagellated cells and an inner mass of nonflagellated cells.

parent, one who has begotten offspring, or one who occupies the role of mother or father. In Western societies, parenthood, with its several obligations, rests strongly on biological relatedness. This is not the case in all societies: in some, a distinction is made between a biological parent and

hydrocarbon: Nomenclature: …in the molecule, called the parent. The alkane shown has seven carbons in its longest chain and is therefore named as a derivative of heptane, the unbranched alkane that contains seven carbon atoms. The position of the CH3 (methyl) substituent on the seven-carbon chain is specified by a number (3-),…

Mergers and acquisitions (known collectively as M&A) are transactions that bring together two businesses. Mergers typically combine two businesses of similar strength, while an acquisition is the purchase of a smaller company by a bigger one. When two companies merge, the entities become one, and

subsidiary: …business firm, known as a parent company or holding company. A parent company is generally understood to be one that conducts its own business operations apart from those of its subsidiary or subsidiaries, while a holding company is one whose sole function is that of ownership. By virtue of its…

subsidiary: …business firm, known as a parent company or holding company. A parent company is generally understood to be one that conducts its own business operations apart from those of its subsidiary or subsidiaries, while a holding company is one whose sole function is that of ownership. By virtue of its…

dating: Principles of isotopic dating: …in a sample containing radioactive parent atoms. The particles given off during the decay process are part of a profound fundamental change in the nucleus. To compensate for the loss of mass (and energy), the radioactive atom undergoes internal transformation and in most cases simply becomes an atom of a…

linguistics: Development of the comparative method: …were able to reconstruct “ancestral” common forms from which the later forms found in particular languages could be derived. By convention, such reconstructed forms are marked in the literature with an asterisk. Thus, from the reconstructed Proto-Indo-European word for “ten,” *dekm, it was possible to derive Sanskrit daśa, Greek déka,…

In a list of life’s certainties, death and taxes come to mind. But here’s a third: Spiraling costs to educate a child. If you’re like many parents, after you get that financial aid letter—including any scholarships, loan offers, and such—you’ll likely still have a gap to fill in order to pay all

Nancy Meyers: …Meyers directed her first film, The Parent Trap, which was based on the 1961 Disney movie. Although a critical and commercial success, it was her last collaboration with Shyer as the couple subsequently parted ways. Meyers next wrote and helmed What Women Want (2000), which featured Mel Gibson as a…

Maureen O’Hara: …Mills’s romantically meddlesome twins in The Parent Trap (1961). In 1963 she reunited with Wayne in McLintock!, in which she played the estranged wife of his character. She paired with Wayne a final time in the 1971 kidnapping drama Big Jake.

Maria Edgeworth: …published them in 1796 as The Parent’s Assistant. Even the intrusive moralizing, attributed to her father’s editing, does not wholly suppress their vitality, and the children who appear in them, especially the impetuous Rosamond, are the first real children in English literature since Shakespeare.

mechanics of solids: Concepts of stress, strain, and elasticity: The French mathematician Antoine Parent introduced the concept of shear stress in 1713, but Coulomb was the one who extensively developed the idea, first in connection with beams and with the stressing and failure of soil in 1773 and then in studies of frictional slip in 1779.

Philadelphia Flyers: Behind the play of goaltender Bernie Parent, three-time league Most Valuable Player Bobby Clarke, winger Bill Barber, and Dave (“the Hammer”) Schultz—a rough-and-tumble winger who became the most notable enforcer on the team—Philadelphia won two Stanley Cups during this period (1974 and 1975), and the team’s bruising style of play…

Jean Nouvel: …formed by the Modernist architect Claude Parent and the “urbanist” and cultural theorist Paul Virilio. Nouvel graduated in 1972 with a degree in architecture.

Tate murders: The Tate and LaBianca murders: …people in the home—celebrity hairstylist Jay Sebring, a close friend of Tate’s, was also there—were made to gather in the living room, and Tate and Sebring were linked by ropes tied around their necks. Sebring was shot and stabbed to death. Frykowski and Folger managed to free themselves and flee…

National Congress of Parents and Teachers, American organization concerned with the educational, social, and economic well-being of children. The PTA was founded on Feb. 17, 1897, as the National Congress of Mothers; membership was later broadened to include teachers, fathers, and other citizens.

National Congress of Parents and Teachers, American organization concerned with the educational, social, and economic well-being of children. The PTA was founded on Feb. 17, 1897, as the National Congress of Mothers; membership was later broadened to include teachers, fathers, and other citizens.

reproductive behaviour: Parental care: Among the organisms that remain with the eggs or offspring, one particular behaviour is striking—that of nest construction to keep the eggs and larvae in one spot and to protect them against predators as well as such environmental factors as sun and rain.…