I

MAGINARY POINTS AND LINES. In analytic geometry a point is said to be imaginary if one or more of its coördinates are imaginary; e.g., the points of intersection of the straight line = 6 and the circle y=4, found by solving the two equations, are x = 6, y = 4 v2, and x = 6, y = −4 V2, the two values of y (i.e., the ordinates of the points) being imaginary, the points of intersection of the given line and circle are said to be imaginary. Similarly, the conjugate axis of the hyperbola (q.v.) cuts the hyperbola in two imaginary points. A line whose equation contains imaginary coefficients is called an imaginary line; e.g., the asymptotes of an ellipse or circle are imaginary lines. Their equations may obtained from the equations of the curves thus: Let x2+ y2 = 0, then (x + yi) ( x − yi) = 0, and x + yi = 0, xyi=0 are the imaginary asymptotes to the circle. Similarly,

be

are the imaginary asymptotes to the ellipse. All of these imaginary lines have the real point x = 0, y = 0. See CONTINUITY.

IMAGINARY QUANTITY. See COMPLEX

NUMBER.

one individual to another; one person may tend to ideate in visual, another in auditory and kinæsthetic, a third in merely kinæsthetic, images. See IMAGE; MEMORY.

The distinction of idea of memory and idea of imagination has usually been the popular or logical distinction, based upon meaning or reference. The idea of memory means or refers to some part of one's past experience (one has a memory-idea of one's home or of a piece of familiar music); the idea of imagination has no personal reference (one imagines a centaur, a golden mountain, a novel phrase of music). This reference, if conscious at all, is in the case of memory an associative context, a feeling of familiarity or "at-homeness," or a conscious In the case of attitude of placing or dating. imagination, since the idea is novel, associated ideas are lacking; and the reference is carried by a feeling of unfamiliarity or strangeness, or by a conscious attitude of search or inquiry. (See MEANING; THOUGHT.) The idea of imagination itself seems to be distinguished from the idea of memory as being relatively complete, and as forming simultaneously, whereas the memoryidea is abbreviated and sketchy, and its phases This differconstitute a development in time. ence may be referred to differences in the interplay of determining and associative tendencies. In remembering, associative tendencies play the leading part; and the resulting formation, provided that it is in any way fitted to mean the experience to be recalled, may be partial or even symbolical. The function of imagination, on the other hand, is to represent a new experience. The idea of imagination must not only mean "something new"; it must be something new, a production rather than a reproduction. This requirement limits the part which association may play, and at the same time is the condition of a strong determining tendency. So the course of ideas in imagination, directed by a stronger and more narrowly defined determination, will be less discursive, more integrative, than that in memory.

The total consciousness in which the idea of imagination is set may show the pattern either of primary or of secondary attention (see ATTENTION), and we may speak accordingly of passive or reproductive and of active or creative imagination.

The first is exemplified in the reading of an interesting novel; the second in mechanical or artistic invention or production.

In both cases consciousness is restricted to processes which are directly determined by the context or by the problem to be solved. If, in creative imagination, attention is limited more closely to ideas sharply selected for expressing a single conception or a single mood, this difference is a matter of degree and not of kind.

Consult: Bain, The Senses and the Intellect (London, 1888); Sully, Outlines of Psychology (New York, 1891); Hoefler, Psychologie (Vienna, 1897); Ambrosi, Psychologia dell' immaginazione (Rome, 1898); William James, Principles of Psychology (2 vols., New York, 1899); Ribot, Essay on the Creative Imagination (Chicago, 1906); Lucka, Die Phantasie (Vienna, 1908); Titchener, Text-Book of Psychology (New York, 1910).

IMA'GO. The adult, sexually mature form of an insect which passes through metamorphoses. See METAMORPHOSIS.

IMAM, ê-mäm' (Ar. 'imām, leader, from 'amma, to lead, set an example). The appellation given in general to teachers among the Mohammedans, as leaders whose example is to be followed. It is commonly employed to designate any of the persons belonging to the Mohammedan ulema (q.v.), or "learned" body. They are distinguished from the laity by a turban somewhat higher than usual and are held in great reverence by the people. Besides this general use, there are also certain specific applications of the term. Among the Shiites (i.e., the followers of Ali) the term "imam" is applied to the 12 legitimate successors of Ali. Among the orthodox Mohammedans the imam is properly the caliph, or leader of the entire body of Mohammedans; but the name is also extended to any authority whose views on theology and law are followed. In the course of time every Mohammedan community came to have its imam, whose chief function it was to lead the congregation in prayer. He takes his stand in front of the group of worshipers, who take up a position behind him arranged in fixed rows and imitate the genuflections and attitudes assumed by the leader in the course of the prescribed prayers.

IMAMITES, &-mäm'īts. A Mohammedan sect whose members recognize the 12 imams, descendants of Mohammed's son-in-law Ali, whom they consider the first real imam, or caliph. They are commonly known as Shiites (q.v.).

IMAZIGHEN, e'må'zê'gäN'. The designation of all the Berber tribes of the Atlas Mountains, in Algeria and Morocco, comprising the Kabyles, Shulluhs, and Haratin. The Kabyles, who call themselves Imazighen, are farthest north and more mixed with Semites and Europeans; the Shulluhs (Shluhs) are to be found on the northward-sloping valleys of the Atlas Mountains, while the Haratin Berbers are on the southern slopes and mixed with negroes. (See KABYLES; SHULLUHS; HARATIN.) They are Hamites fundamentally in blood, but have long been accultured with Arab speech and religion. Their mountain retreats have enabled the Imazighen Berbers to preserve their ancient patriarchal mode of life, so that many hundreds of clans and families keep up their small organizations at the same time that they are united into larger nations. Consult Bertholon and Chantre, Recherches anthropologiques dans la Berbérie Orientale (Lyons, 1913). IMBATTLED. See EMBATTLED. IM/BECILE. See MENTAL DEFECTIVES,

IM BECIL/ITY (from Lat. imbecillitas, weakness, from imbecillus, weak). 1. Mental weakness or defect. Imbecility and idiocy are comparative terms. They are both states due to similar processes, consisting of imperfect development of the brain, and due to congenital influences or acquired injury or disease. (See IDIOCY.) Thus, it is almost impossible to determine the dividing line that separates an idiot from an imbecile, and such differentiation may entail much study and careful following of the mental development. In general understanding, an idiot is unable to attend to the simple primary affairs of his organization. An imbecile is able to attend to these. At the other end of the scale the imbecile shades into the normal average human mind by imperceptible gradations, and it may be just as difficult to separate the imbecile from feeble-minded, dull, and stupid individuals as it is to separate the idiots from imbeciles. There are large numbers of weak-minded, useless persons in every community who differ from the more robust intellects solely in degree. These are largely imbeciles or feeble-minded. But the more marked and recognizable idiocy is characterized by many of the following signs: the vacant expression, dull senses, small head, deformed body, vacillating and restless gait; pendent, thrown back, or agitated head; escaping saliva, limited and infantile language. The ideas may be few and consist of mere sensuous impressions; the temper, timid, facile, and vain; and the passions are little susceptible of control. The idiot is profoundly defective and largely unteachable. The higher grades may be slightly trained in self-help. The imbecile responds to training and generally may be materially improved, but cannot take an independent place in the world. With close moral support he may ply a simple trade and earn his living.

2. As a generic legal term, a weakness of mind falling short of idiocy (q.v.) on the one hand and full mental capacity to contract or to distinguish between right and wrong on the other. The victim of imbecility, using the word in this sense, is not absolutely incapable of binding himself by contract or of committing crime. If his weakness is taken advantage of by another, any contract or conveyance so secured may be set aside; but the mere fact that a man is of weak understanding, or that his intellectual capacity is below the average of mankind, if no fraud or no undue advantage be taken, is not of itself an adequate ground to set aside a transaction. It should be added that a lower degree of intelligence is required for a valid will than for a business contract or conveyance. In various jurisdictions imbeciles are more or less protected against the fraud of others or their own acts of indiscretion by placing them more or less under the control of others, as in Scotland by interdiction or by the appointment of a committee or guardian. Consult Barr, Mental Defectives (Philadelphia, 1904), and Goddard, Feeble-Mindedness: Its Causes and Consequences (New York, 1914). See INTERDICTION; COMMITTEE; GUARDIAN; also see IDIOCY; INSANITY; LUNACY; and the authorities there referred to.

IMBER, im'ber, NAPHTALI HERZ (18541909). A Hebrew poet and Cabbalist, born of poor parentage at Zloczow in Galicia. He received a thorough training in the Talmud and after the age of 14 led the life of a wandering

scholar, visiting in turn Constantinople, Egypt, and Palestine. There he studied the Oriental languages and especially Hebrew. From Palestine he went to England, where he worked for some time in collaboration with Israel Zangwill, whom he taught the Yiddish language. In 1892 he came to America and made his home at different times in New York City, Boston, Chicago, San Francisco, and Los Angeles. In addition to many volumes of poetry and Cabbalistic lore, he wrote extensively for the Hebrew press. In his mastery of the ancient language of the Bible he takes rank with the leading scholars of Europe and America. His poetical works in form and thought are modeled to a great extent upon the songs of Judah ha Levi (q.v.), whose fervent love for and hope in Zion Imber more than echoes. Among his works are: Austria, a poem; The Mystery of the Golden Calf; The Keynote to Mystic Science; The Treasures of Ancient Jerusalem; The Letters of Rabbi Akibah; The Education of the Talmud, printed by the United States government; Music of the Psalms. His "Hope of Zion" has become the hymn of the Zionist party the world over.

IMBERT DE SAINT-AMAND, ănʼbâr de sǎn'tå'män', ARTHUR LÉON, BARON (1834-1900). A French author, born in Paris. He was privately educated, studied law, and after being admitted to practice entered the government service in the Department of Foreign Affairs. Here he rose through the several ranks to the grade of Minister Plenipotentiary of the first class in 1882 and was assigned to special service in the central offices of the department in Paris. He is best known as the author of an interesting and popular series of biographical and social studies of the women of the French courts. The first of these, entitled Les femmes de Versailles (5 vols., 1875-79), covered the period from Louis XIV to the close of the ancien régime; the second, Les femmes des Tuileries (37 vols., 1880-99), began with the last days of Marie Antoinette and concluded with the women of the Second Empire. The series has been translated into English under the title of Women of the French Court. Among his other published works, some of which have also been translated into English, are: Portraits de femmes françaises du XVIII et du XIX siècle (1869); Les femmes de la cour des derniers Valois (1872); Madame de Girardin (1874); Portraits de grandes dames (1875); La cour de Louis XVIII (1891); La cour de Charles X (1891).

IMBIBITION, im'bi-bish'un (from Lat. imbibere, to drink in, from in, in + bibere, for *pibere, to drink, Skt. pā, to drink, OIr. ibim, I drink). The physical process of swelling of solids by the absorption of liquid. It is exhibited most freely by organized bodies, i.e., those formed by living beings, which have therefore a characteristic structure, but is not confined to them. The swelling depends on a separation of the structural units of the body, which are believed to be not its molecules but rather molecular complexes. Imbibition, therefore, differs from solution in that the separation of the particles is not so extensive; and when the water is removed by evaporation or otherwise they return to their original relations, so that the body regains its previous form and structure. After solution, on the contrary, the separated molecules may rearrange themselves completely. In a normal condition all parts of plants hold large quantities of water imbibed in

their substance. Even in the walls of wood cells, the least watery material, there is usually 50 per cent of water, while in the protoplasm there may be as much as 95 per cent. Indeed, the plant may be considered as a mass of water held between the structural particles of the cells composing it and exceeding in volume the material by which it is so held. This condition alone makes it possible for plants to obtain materials from the water and air about them. See ABSORPTION, IN PLANTS.

a

The force of imbibition results from the surface of the ultramicroscopical particles, making up the swelling body, adsorbing water or other liquids imbibed. When a dry starch grain imbibes water, heat is developed (on account of the compression of the water) to an amount which indicates (according to Rodewald) pressure of over 2500 atmospheres. The force exerted by a confined swelling body is at first enormous, but becomes rapidly weaker as the particles are separated farther and farther. Correspondingly water is held loosely when abundant, but more and more tenaciously when only a little is imbibed. Thus, when a bit of laminaria is completely swollen, water can be removed from it by slight pressure; when it holds 170 per cent of water, it requires a pressure of 16 atmospheres to extract water; when only 93 per cent is present, a pressure of 200 atmospheres is needed. Applications of the force of swelling are made in splitting stone by wooden wedges driven in and then wetted, in shortening ropes by wetting, in the use of laminaria for surgical distention, etc. The phe

nomena of imbibition afford the chief basis for theories concerning the molecular structure of organized bodies. See COLLOIDS; ADSORPTION.

IMBRIANI, êm'brê-ä'nê, VITTORIO (184086). An Italian poet and critic, born in Naples. He pursued studies in the universities of Naples, Zurich, and Berlin, and took part in the campaigns of 1859 and 1866. In 1884 he was appointed to the chair of æsthetics at the university of his native city, but was then too ill to assume the duties of this post. His political life was a troubled one by reason of his excessively passionate nature, which excited bitter antagonism. He is best known for his collections of popular tales and verse, such as Canti popolari delle provincie meridionali (1871-72), Dodici canti pomiglianesi (1876), La novellaja fiorentina (1877), etc. A number of his poems are to be found in a collection entitled Esercizj di prosodia (1874). Among his critical works are some monographs on Dante, and the Fame usurpate (1877), in which he seeks to demonstrate that Goethe's Faust is a production devoid of all merit.

IM'BRICATED SNOUT BEETLE. A very injurious weevil (Epicarus imbricatus), which damages many different kinds of garden vegetables and fruits, such as onions, radishes, cabbages, beans, watermelons, cucumbers, corn, beets, and strawberries, by sucking the juices of the leaves, stems, roots, or fruit. It also punctures the leaves and twigs of the apple and pear. The life history is not thoroughly known, although the eggs and young larvæ found on the leaves of the strawberry have been described by Chittenden. The best remedy consists in spraying with a Paris green or some other standard mixture.

IMBROGLIO, êm-brōl'yo (It., confusion). A musical term denoting the synchronous execu

The passage must be executed so that the first nine eighth notes of the voice coincide exactly with the first six eighth notes of the orchestra. Voice and instruments come together on the first and third beats of the bar, but not on the second. Another famous example is found in the scene of the Last Supper in Parsifal (Act i). Against arpeggios of the strings in 4/4 time the wood wind executes a rhythmic figure in 6/4 time in such a manner that the two groups of instruments come together on the first and third beats, but not on the second and fourth. The most extended and complicated employment of imbroglio occurs in the finale of the second act of Die Meistersinger.

IMBROS, êm'bros. A Turkish island in the Egean Sea, situated about 13 miles northeast of Lemnos (Map: Greece, E 4). Area, about 87 square miles. It is of volcanic origin, rocky, and mostly barren, but a small part of its area is very fertile. It produces wheat, barley, oats, olives, and fruit. Pop., about 8000, mostly Greeks, engaged in fishing. The chief town is Kastron (Castro), the seat of a Greek bishop.

IMERITIA, e'mê-rish'i-a. Formerly an independent kingdom in Georgia (q.v.), now constituting a part of the Government of Kutais (q.v.) in Russian Transcaucasia. Its history as an independent country begins towards the end of the fifteenth century. In 1621 it first asked Russia for aid and came under her suzerainty in 1650. About 1750 it was occupied by the Turks, who were expelled by the Russians in 1769. In 1810 it was annexed to Russia. The Imers, or Imeritians, who number less than half a million, are one of the tribes belonging to the southern, or Georgian, group of peoples of the Caucasus. They are considered by Pantiukhoff to be the purest representatives of the primitive Georgian type. See GEORGIANS.

IMHOFF, êm'hof, AMALIE VON. See HELVIG. IMHOFFER, êm'hôf-er, GUSTAV MELCHIOR (1593-1651). An Austrian Jesuit and South American explorer. He was born near Graz, Styria, and went to Peru as a missionary in 1624. Twelve years afterward he crossed the Andes to the source of the Amazon and was the first European to leave upon record his exploration of that stream to its mouth. His account was published in two volumes in Madrid (1640) and in London (1689), the latter edition called A Relation of a Journey along the River Amazon. Father Imhoffer was head of the Jesuit

by the Society of Jesus 20 years after his death.

The

IMHOOF-BLUMER, êm'hōf bloo'mer, FRIEDRICH (1838- ). A German numismatist, known as an authority on Greek coins. Born at Winterthur, he became interested in numismatics as a boy, gave up the business career planned for him, received a classical education, and amassed a valuable collection of more than 20,000 ancient Greek coins, bought in 1900 by the Royal Numismatic Cabinet in Berlin. great work of the Prussian Academy of Science, Die antiken Münzen Nordgriechenlands (1899 et seq.), was undertaken at his instance; and in 1901 he gave to the Academy the sum of 100,000 francs for the promotion of the science of numismatics. He wrote: Zur Münzkunde und Paläographie Böotiens (1871); Die Münzen Akarnaniens (1878); Porträtköpfe auf römischen Münzen (2d ed., 1893); Porträtköpfe auf antiken Münzen hellenischer und hellenisierter Völker (1885); Zur Münzkunde Grossgriechenlands (1886); Tier- und Pflanzenbilder auf Münzen und Gemmen (1889), with Keller; Lydische Stadtmünzen (1897); Kleinasiatische Münzen (1901-13 et seq.), as well as the great illustrated works, Monnaies grecques (1883) and Griechische Münzen (1890).

IMHOTEP, êm-ho'těp. An Egyptian divinity, identified with Esculapius; the son of Ptah and Sekhmet, who with Imhotep formed the triad chiefly honored at Memphis.

IMITATION (Lat. imitatio, from imitari, to imitate). The repetition of any thought, feeling, or act, or the copying of any example or model. The term is sometimes used in a narrower sense, to denote behavior, the model for which is another person or another like individual.

Imitation, as such, may be conscious to the imitator, as in learning a foreign language; or it may be unconscious, as when an individual in a crowd unknowingly feels and acts like his neighbors. Conscious imitation is to be explained in the same way as voluntary behavior at large. (See ACTION; WILL.) Unconscious imitation-behavior which is imitative, not to the imitator but only to the reflecting onlooker requires further consideration. There seems

to be no sufficient ground for assuming a general instinct of imitation, an inherited tendency to duplicate all impressions either in kind or symbolically. Only certain modes of behavior