reed organ, an organ in which air is forced over free reeds by means of bellows, usually worked by pedals. It is played by the use of one or more keyboards. Variations in tone are produced by stops that control different sets of reeds or vary the manner in which the air acts upon them. Couplers add the upper or lower octave of each tone played. In the late 18th cent. C. G. Kratzenstein built a small reed organ, inspired by the Chinese sheng. In 1810, G. J. Grenié of Paris invented the orgue expressif, and numerous similar instruments followed. Most of these, including the harmonium, as modified in 1840 by Alexandre Debain of Paris, had bellows that blew the air over the reeds, but c.1835 a workman conceived the idea of employing suction bellows. His idea was used by Jacob Estey of Brattleboro, Vt., and Mason Hamlin of Boston in the mid-19th cent. American organ, melodeon or melodium, and cabinet organ were the names generally applied to this type of instrument, although the terms harmonium and melodeon have sometimes been confused. Both types of instrument found wide use in churches and homes in the United States. Many larger modern reed organs are electrically powered and have pedal keyboards like those of the pipe organ.

organ transplant: see transplantation, medical.

organ, a musical wind instrument in which sound is produced by one or more sets of pipes controlled by a keyboard, each pipe producing only one pitch by means of a mechanically produced or electrically controlled wind supply.

Early Organs

Ktesibios of Alexandria, in the 3d cent. B.C., invented the hydraulis, in which water pressure was used to stabilize the wind supply. The pipes were arranged in rows upon the wind chest and the air was permitted to enter any pipe at will by means of wooden sliders. The hydraulis was the prevailing organ for several centuries and reappeared at intervals throughout the Middle Ages.

Evidence of the first purely pneumatic organ is found on an obelisk erected at Byzantium before A.D. 393. Byzantium became the center of organ building in the Middle Ages, and in 757 Constantine V presented a Byzantine organ to Pepin the Short. This is the earliest positive evidence of the appearance of the organ in Western Europe. By the 10th cent., however, organ building had made considerable progress in Germany and England. The organ built c.950 in Winchester Cathedral is said to have had 400 pipes and 26 bellows and required two players and 70 men to operate the bellows.

The keyboard, or manual, was a creation of the 13th cent., making possible the performance of more complex music. The earliest extant music written specifically for organ, dating from the early 14th cent., gives evidence that by then the manuals of the organ had full chromatic scales, at least in the middle registers. Organs in the Middle Ages already had several ranks of pipes, each key causing a number of pipes to sound simultaneously. All were diapasons, or principals, the pipes of timbre characteristic only of the organ, and the various pipes controlled by one key were tuned to the fundamental and several harmonics of a given tone.

The Development of the Modern Organ

The 15th cent. saw considerable development of the organ, particularly in Germany and Flanders. It became possible to sound single pipes from a rank through the use of stops. Mutation and mixture stops that produce several harmonics of the unison pitch came to be used in combination with the unison to vary tone color. Solo stops imitative of other instruments, mainly flute and reed pipes, were added, and the pedal became standard. Until the 19th cent., Italy and England preferred an organ with no pedals.

It was the Flemish and German builders who developed the organ of distinctive and contrasting timbres, and the peak in organ building was reached in the German organ of the baroque, as described by Michael Praetorius in his Syntagma musicum (1618). The greatest organ builder, perhaps of all time, was Gottfried Silbermann (1683-1753) of Dresden. His organs produced a light, transparent tone, ideal for the performance of the great baroque polyphonic music. After this period the art of organ building degenerated, and the organ lost its place in the center of musical life.

The 19th-century desire for a highly expressive organ led to the obscuring of diapason tone by the large number of stops imitative of orchestral tone and to the common employment of the swell and the crescendo pedal. The swell involves enclosing one or more divisions of the organ in a wooden box on one side of which are shutters opened or closed by means of a swell pedal; the crescendo pedal, when gradually opened or closed, adds or takes off stops one by one.

The early 20th cent. saw the electrification of the mechanical parts of the organ, fulfilling the trend toward monstrous size and overwhelming power. In America, this large "king of instruments" became a feature of municipal auditoriums, movie palaces, churches, department stores, schools, and many other institutions. The master architect of these colossal orchestral organs was Ernest M. Skinner. In the early 20th cent., however, Albert Schweitzer was active in the preservation and restoration of many fine old organs, and there was a movement back to the ideals of Silbermann. In the United States, Walter Holtkamp, beginning in 1932, and G. Donald Harrison, in 1935, became the leading figures in this movement. Harrison designed many organs suitable for the performance of music of all periods. In the United States much of the repertoire was performed by the two leading organists of the era, E. Power Biggs and Virgil Fox. By the beginning of the 21st cent., European and American organ builders continued to concentrate on early principles for the construction of their instruments.

Music for the Organ

The organ repertory is vast and varied. The great organ masterpieces of the 17th and 18th cent. include works by John Bull, Handel, Jan Sweelinck, Girolamo Frescobaldi, and Dietrich Buxtehude. In the compositions of J. S. Bach the capabilities of the organ found their most magnificent expression.

mouth organ: see harmonica 1.

barrel organ, mechanical musical instrument requiring nothing but the regular rotary motion of a handle to keep it going. It probably originated at the beginning of the 18th cent., and was once used extensively in English churches. A revolving cylinder is fitted with pegs that open valves, permitting air to enter a set of organ pipes. Some larger ones have several sets of pipes and various couplers. They can be operated by clockwork, by weights, and by electric motors. A portable type of barrel organ whose cylinder is turned by a hand crank has been mistakenly called hurdy-gurdy, from which it is fundamentally different.

Organ Pipe Cactus National Monument: see National Parks and Monuments (table).

or pineal body

Endocrine gland in the brain that produces melatonin. It is large in children and begins to shrink at puberty. The gland may play a significant role in sexual maturation, circadian rhythm and sleep induction, and seasonal affective disorder and depression. In animals it is known to play a major role in sexual development, hibernation, and seasonal breeding.

Learn more about pineal gland with a free trial on Britannica.com.

or graft

Partial or complete organ or other body part removed from one site and attached at another. It may come from the same or a different person or an animal. One from the same person—most often a skin graft—is not rejected. Transplants from another person or, especially, an animal are rejected unless they are unusually compatible or have no blood vessels (e.g., the cornea), or if the recipient's immune reaction is suppressed by lifelong drug treatment. Transplanted tissues must match (by blood tests) more closely than blood transfusions. Monoclonal antibodies targeting the cells that cause rejection hold great promise. Tests are now under way with monoclonal antibodies that react with antigens present only on T cells that are participating in rejection, sparing the rest. Rejection matters less in skin grafts, which may need to last only weeks, and bone grafts, whose structure remains after the cells die. In bone-marrow transplants, the donor's marrow cells may attack the recipient's tissues, often fatally. Lung transplants have greater chance of success as part of a heart-and-lung transplant. Seealso heart transplant, kidney transplant.

Learn more about transplant with a free trial on Britannica.com.

or renal transplant

Replacement of a diseased or damaged kidney with one from a living relative or a legally dead donor. The former's tissue type is more likely to match, reducing the chance of rejection; but removal puts the donor at risk, and a kidney from a dead donor is more likely to be available. The new kidney is implanted and its blood vessels and ureter sewn in place. A near-normal life may be resumed within two months, but the drugs that prevent rejection leave the patient vulnerable to infection. Seealso transplant.

Learn more about kidney transplant with a free trial on Britannica.com.

Procedure to remove a diseased heart and replace it with a healthy one from a legally dead donor. The first was performed in 1967 by Christiaan Barnard. The diseased heart is removed (except for some atrial tissue to preserve nerve connections to the natural pacemaker). The new heart is put in place and connected to the recipient's blood vessels. Patients and donors are matched for tissue type, but the patient's immune system must still be suppressed to prevent rejection (see immunosuppression). A successful transplant can enable the recipient to have an active life for many years.

Learn more about heart transplant with a free trial on Britannica.com.

Keyboard instrument in which pressurized air produces notes by means of a series of tuned pipes. The simplest organs consist of a single rank of pipes, each corresponding to a single key. They are arranged over a wind chest connected to the keys by a set of valves and fed with a supply of air by electrically or mechanically activated bellows. By pulling out knobs, called stops, the player engages new ranks of pipes. Two distinct types of pipes are used: flue pipes (both open and stopped) produce sound by directing air against the edge of an opening in the pipe, whereas reed pipes sound by means of a thin metal tongue inside the pipe that vibrates against a fixed projection next to it. A large organ may have five or more banked keyboards, or manuals, each of which controls a distinctive group of pipes. Most organs also have pedalboards played with the feet. A large organ's pipes may vary in length from about 1 in. to 32 ft (2.5 cm to 10 m), resulting in a huge nine-octave range. The earliest organ (circa 250 BC) was the Greek hydraulis, in which the wind was regulated by water pressure. The bellows-fed organ appeared about the 7th century AD. The organ became firmly associated with the church by the 10th century. As organs became widespread, different regions pursued different modes of construction and sought different tonal ideals. The Baroque German organ is ideally suited to polyphony, while the French taste for variety of timbres eventuated in Aristide Cavaillé-Coll's vast “orchestral” organs. Seealso harmonium.

Learn more about organ with a free trial on Britannica.com.

National monument, southwestern Arizona, U.S., at the Mexican border. It was established in 1937. With an area of 330,689 acres (133,929 hectares), it preserves segments of the mountainous Sonoran Desert and is named for the organ-pipe cactus. Wildlife includes Gila monsters, antelope, coyotes, and a variety of birds.

Learn more about Organ Pipe Cactus National Monument with a free trial on Britannica.com.

(born Jan. 1, 1879, London, Eng.—died June 7, 1970, Coventry, Warwickshire) British writer. Forster was born into an upper-middle-class family. He attended the University of Cambridge and from roughly 1907 was a member of the informal Bloomsbury group. His early works include Where Angels Fear to Tread (1905), The Longest Journey (1907), A Room with a View (1908), and his first major success, Howards End (1910), novels that show his acute observation of middle-class life and its values. After periods in India and Alexandria, he wrote his finest novel, A Passage to India (1924), examining the failure of human understanding between ethnic and social groups under British rule. Maurice, a novel with a homosexual theme written in 1913, appeared posthumously. Aspects of the Novel (1927) is a classic discussion of aesthetics and the creative process. Awarded an honorary fellowship in 1946 at Cambridge, he lived there until his death.

Learn more about Forster, E(dward) M(organ) with a free trial on Britannica.com.