ISLAND FAUNA. For the general characteristics of the fauna of islands, see ISOLATION. Examples of individual peculiarities in island faunas will be found under GALAPAGOS ISLANDS, etc.

BIBLIOGRAPHY. Suess, Das Antlitz der Erde (Stuttgart, 1885, 1888); de la Noë and de Margerie, Les formes du Terrain (Paris, 1888); Wallace, Island Life (London, 1891).

ISLAND CITY, THE. A name for Montreal. ISLAND NUMBER TEN. An island which existed, until shortly after the Civil War, in the Mississippi River, about 40 miles below Columbus, Ky. (near the boundary line between Kentucky and Tennessee), thus named from its position in the series of islands below Cairo, Ill. After the first Confederate line in the West had been broken by the capture of Forts Henry and Donelson (q.v.), the garrison at Columbus, Ky., constituting the Confederate left flank, was withdrawn to New Madrid (q.v.) and Island Number Ten and placed in command of General McCown, who was later replaced by General Mackall. Early in March, 1862, a Federal army under General Pope and a Federal fleet under Commodore Foote advanced against these positions. On the 16th New Madrid surrendered to

Pope, who then marched about 25 miles down the river, and with the assistance of transports which had been brought through a laboriously constructed channel, across a peninsula formed by a loop in the Mississippi, from a point above the island to New Madrid, succeeded in attaining the Confederate rear at Tiptonville, the Confederate batteries along the east bank having been previously silenced by the gunboats Carondelet and Pittsburgh, which, under Captain Walke and Lieutenant-Commander Thompson, had successfully run by the island on April 3d and April 7th, respectively. Meanwhile Foote's fleet had kept up a fairly continuous though ineffective bombardment. The Confederate garrison, which numbered between 6000 and 7000, threatened in front and rear, and completely cut off from retreat by the Federal forces and impenetrable swamps, finally surrendered on April 7th. The Federal loss was less than a dozen men. The cutting of the channel across the peninsula formed by the Icop in the river required great labor and considerable engineering skill, while the running of the batteries by Henry Walke (q.v.) was not only one of the most dramatic deeds of the war, but completely overcame the Confederate defense of this position. After the war the old Island Number Ten was gradually washed away by the river, and a new one was slowly formed on the opposite shore. Consult: Johnson and Buel (editors), Battles and Leaders of the Civil War, vol. i. (4 vols., New York. 1887); Mahan, The Gulf and Inland Waters (New York, 1883).

ISLAND OF SAINTS (Lat. Insula Sanctorum). A name given to Ireland in the Middle Ages, from her great number of ecclesiastics and missionaries.

ISLANDS OF THE BLESSED (Lat. Fortunate Insula, Gk. ai tŵv μakápwv vĥσoɩ, hai tōn makarōn nēsoi). According to an old Greek myth, certain islands situated toward the edge of the western ocean, where was the abode, not of departed spirits, but of certain favored mortals, rescued from death by the gods. Here life was most easy, the climate soft and springlike, and

there was abundance of all things. Homer calls the spot the Elysian Plain (Od., iv., 563), but Hesiod, Works and Days, 168, and Pindar, Ol., ii., with later poets, speak of islands. Later authors identified the islands with the Canaries, lying outside the Pillars of Hercules, in the Atlantic Ocean.

ISLAND OF THE SEVEN CITIES. A legendary island settled by seven bishops and refugees from Spain and Portugal at the time of the Moorish Conquest.

ISLAY, I'lâ. A Scottish island, one of the Inner Hebrides, included in Argyllshire, 15 miles west of the Peninsula of Cantire, and southwest of the island of Jura, from which it is separated by the Sound of Islay (Map: Scotland, B 4). Area, 220 square miles, of which about 22,000 acres are under cultivation. The north of the island is hilly, and along the eastern shore runs a ridge rising from 800 to 1400 feet in height. The central and western districts are undulating or flat. Whisky-distilling is the principal industry. Population, in 1901, 6891.

ISLE BIUS, MAGISTER. A name sometimes applied to Luther's disciple Johann Agricola (q.v.).

ISLE OF LADIES.

Chaucer, which first appeared in Speght's edition A poem attributed to (1597) of Chaucer. It is also called "Chaucer's Dream."

ISLE OF LANTERNS.

In Rabelais's Pan

tagruel, an island peopled by pretended wise

men.

ISLE OF MAN. See MAN, Isle of.

ISLE OF PINES, or Sp., ISLA DE PINOS, ĕ'slå då pe'nôs. An island belonging to Cuba, situated about 40 miles southeast of the southern coast of the Province of Pinar del Río (Map: Cuba, C 5). It is almost circular in outline, with a diameter of about 40 miles and an area of 840 square miles. It is hilly and well forested with pine, cedar, and mahogany in the northern part, while the southern consists of a low marsh, similar to the Everglades of Florida, covered with mangrove thickets and presenting a luxuriant wealth of native flora and fauna. The soil of the northern part is sandy and favorable to the growth of pineapples and potatoes, the latter being of excellent quality. There are some mineral deposits, of which only the marble-quarries are exploited. Cattle-raising is, however, the chief source of wealth of the inhabitants, who in 1899 numbered 4076, chiefly concentrated in the town of Santa Fé and the capital, Nueva Gerona, situated near the northern coast. See Bryan, Our Islands and Their People (New York, 1899).

ISLE OF WIGHT. See WIGHT, ISLE OF.

ISLES, LORDS OF THE. A line of Scottish chiefs, celebrated in poetry and rómance. Sir Walter Scott, in his notes to The Lord of the Isles, speaks of Somerled as Lord of the Isles; but it is probably more correct to speak of him as King of the Isles. The later lords of the isles traced their descent from him. He appears prominently in Scottish history in the middle of the twelfth century, during the reigns of David I and his grandson and successor, Malcolm IV. The race to which he belonged is uncertain; probably, like most of his subjects, he was of mixed descent, Norwegian and Celtic. Barbour says that one of his descendants, Angus of the

Isles, gave his fealty to Bruce when the latter was most hard pressed at the beginning of his reign, receiving him into his castle of Dunaverty, and that he afterwards fought under the Great King at Bannockburn. This chief is the hero of The Lord of the Isles, but his name, for the sake of euphony, has been changed to Ronald. John Macdonald, first Lord of the Isles, son of Angus Og, received a grant from Edward Baliol of Mull, Skye, Isla, Giblia, Kintyre, Knapdale, and other lands. He married Margaret, daughter of Robert II., founder of the Stuart dynasty. During the troubled and disastrous reign of David II., John of the Isles was able to maintain himself in a state of practical independence of the Scottish Crown. He was at last, however, compelled to submit. He met David at Inverness in 1369, and gave hostages for his fidelity. He died about 1386. The most powerful of this race was Donald, eldest son of John. He set the kings of Scotland at defiance, and made treaties as an independent sovereign with the kings of England. He married Mary Leslie, daughter of Euphemia, Countess of Ross. Mary's brother, Alexander, Earl of Ross, by his marriage with the daughter of the Regent Albany, left an only child, who be

came a nun. Donald claimed the earldom in his

wife's right, and when his claim was refused by the Regent he prepared to maintain it by force. Taking possession of Ross, he marched at the head of a large army from Inverness, through Moray and Aberdeenshire, and threatened to destroy the burgh of Aberdeen. Donald was defeated at Harlaw by the Earl of Mar on July 25, 1411. He died about 1420 and was succeeded by his son Alexander. John, son of Alexander, in 1463 made a treaty with Edward IV. of England, by which he promised to assist the English monarch in the conquest of Scotland.

Throughout their history the Lords of the Isles plotted against the Scottish Crown and were a constant menace to the tranquillity of the realm. The last lord was John, who forfeited his title in 1493. After him there were several spurious claimants. In 1540 the Crown annexed the lordship of the Isles. Consult: Gregory, History of the Western Highlands (Glasgow, 1881); Skene, The Highlanders of Scotland, edited by Macbain (Sterling, 1902); Mackenzie, History of the Macdonalds (Inverness, 1882).

ISLES OF SHOALS. A cluster of eight barren, rocky islands in the Atlantic Ocean, off the coast of New Hampshire, 10 miles southeast of Portsmouth (Map: New Hampshire, L 10). The two largest are Appledore, containing 400 acres, and Star, 150 acres. On these are large hotels for visitors, who resort there for the sea air, boating, and fishing. A steamer runs daily from Portsmouth. On White Island is a revolving light 87 feet above the sea. These islands are inhabited by a few fishermen.

ISLETA, ê-sla'tå. An important pueblo of Tanoan stock, situated on the west bank of the Rio Grande, a few miles below Albuquerque, New Mexico. It ranks third among the pueblos, coming after Zuñi and Laguna, with a population of about 1030. As in all other pueblos, the people are peaceable, industrious, and self-supporting, the official returns for 1900 showing over 3500 bushels of wheat and nearly 12.000 bushels of corn to their credit, besides miscellaneous vege tables, all produced from an arid soil by aid of native irrigation.

Isleta, or Ysleta, is also the name of a small pueblo on the north bank of the Rio Grande, about 14 miles below El Paso, in Texas. It was originally established under mission auspices by refugees from the original Isleta, above noted, who accompanied the Spanish army on its retreat from New Mexico in the Pueblo revolt in 1680. Although considerably Mexicanized, the inhabitants still keep their Indian form of government, their dances, foot-races, and language. See also PUEBLO.

ISLE VERTE, ěl věrt. A town, subdistrict, island, and river of Quebec, Canada. The town is the capital of Temiscouata County, and stands on the right bank of the Saint Lawrence at the mouth of the Isle Verte River and opposite the Isle Verte (Map: Quebec, G 2). It has a station on the Intercolonial Railway. The inhabitants are mostly French Canadians. Population of census-subdistrict, 1901, 2256.

ISLEWORTH, il'wêrth. A suburb of London. See HESTON AND ISLEWORTH.

ISLINGTON, iz'ling-ton. A metropolitan borough of London, in Middlesex, comprising four parliamentary divisions, two and a half is the Royal Agricultural Hall with a capacity miles north of Saint Paul's. In Liverpool Road for 50,000 persons, in which the national horse ulation of borough, in 1891, 319,155; in 1901, and cattle and other great shows are held. Pop

334,928.

IS LIP. A town in Suffolk County, N. Y., on Great South Bay, 43 miles east of New York City, on the Long Island Railroad (Map: New York, G 5). It is about 12 miles in length and 10 miles in width, comprising a number of villages. Islip is a summer resort with many costly residences. Great South Bay, attractive for sailing, is frequented also at other seasons for fishing and hunting. Within the limits of the town are the Manhattan State Hospital, Saint Joseph's Convent, and a fish hatchery. Another point of interest is the Fire Island Lighthouse, 166 feet high. Blue Point oysters are shipped in great quantities. The government is vested in a supervisor, elected biennially, and a town board, made up of the justices of the peace, town clerk, and the supervisor. Population, in 1890, 8783; in 1900, 12,545; in 1905, 13,721.

ISMAIL, ês'mȧ-el'. Capital of a district of the same name in the Government of Bessarabia, Russia, situated on the north bank of the Kilia, an arm of the Danube, and on the Rumanian frontier (Map: Russia, E 5). It carries on a considerable trade in grain and other agricultural products and has a custom-house. Its position on the frontier adds greatly to its commercial importance. Its manufacturing establishments include a large number of flour-mills, brick-kilns, a crockery-kiln, tannery, etc. Steamships connect it with Odessa and other Black Sea and Danube ports. Population, in 1897, 33,607. Ismail is mentioned in the sixteenth century as a fortress, and was of great strategical importance under the Turkish rule. In 1632 it was sacked by the Cossacks. It was taken and destroyed by Suvaroff in December, 1790; came into the possession of Russia in 1812; was assigned to Moldavia by the Treaty of Paris, 1856, and transferred to Russia again by the Berlin Congress of 1878.

ISMAILIA, ês’må-ē ́lê-å. A village of Africa. See GONDOKORO.

on the Suez Canal.

dence in Constantinople, where he died March 2,

MEDAN SECTS.

ISMAIL PASHA, es'må-ēl' på-shä' (183095). Viceroy and Khedive of Egypt. He was the second son of Ibrahim Pasha (q.v.), and was born at Cairo, December 31, 1830. He was educated in Paris, and on his return to Egypt was dispatched on diplomatic missions to several European capitals. Subsequently he was appointed regent by his uncle, Said Pasha, during his absence in Europe. In 1861 he was placed in command of the army, and carried on a victorious campaign against the Sudanese tribes. On the death of Said Pasha in 1863 he succeeded him as Viceroy of Egypt. During the Civil War in America he acquired vast wealth by the production of cotton. Regarding the construction of the Suez Canal (begun under Said Pasha) as advantageous for Egypt, he actively encouraged the enterprise. In 1866 he secured from the Sultan the hereditary succession to the throne of Egypt in his direct line, and in 1867 had conferred upon him the title of Khedive. Not satisfied with these privileges, he demanded more, threatening to withdraw the troops he had sent against the Cretan insurgents and to seize Crete if his demands were refused. By the advice of foreign powers, he recalled his demand. Nevertheless, by extending his rule over the regions of the Upper Nile, by making foreign loans for the increase of his army and navy, and by proposing the neutralization of the Suez Canal, he made himself practically an independent sovereign. The Sultan commanded him to reduce his army, to recall his orders for ironclads and breech-loaders, and to put a stop to the contraction of foreign loans, threatening him with deposition if he refused. Not receiving the expected aid from Russia and other powers, Ismail submitted. Later he received new prerogatives, giving him control of his army, and liberty to make loans and commercial treaties. By the building of public roads, the introduction of new methods of agriculture, and other innovations, he endeavored to improve the economic condition of the country and to civilize the surrounding tribes. But the progressive measures of the Khedive were accompanied by a reckless extravagance which involved the country to the limit of its resources and made it dependent upon the great financial powers. In 1879 the governments of France and England, in view of the wretched economic condition of Egypt and the large interests of their own citizens in the administration, determined to interfere in behalf of good government, and united in demanding of the Porte that the Khedive should commit the portfolios of finance and public works to English and French ministers. The Khedive resented any interference of the Western powers with Egyptian affairs. The Sultan then offered to depose Ismail Pasha, and to appoint Halim Pasha, Ismail's uncle, as his successor; but the powers advised the Khedive to abdicate, promising to support his son, Tewfik. The Sultan acquiesced in the course recommended, and on June 26, 1879, he signed the firman deposing the Khedive in favor of his son, Prince Mohammed Tewfik. Ismail at

ISNARD, ê'när', MAXIMIN (1758-1830). A French politician, born at Grasse. In 1791 he was Deputy from Var to the National Assembly, in which he distinguished himself by his beldness and eloquence. He was reëlected in 1792. He joined the Girondists, and was arrested in June, 1793, but escaped and concealed himself until the fall of Robespierre. He appeared again in the Assembly, and afterwards was a member of the Council of Five Hundred. From a violent radical he developed into an advocate of the coronation of Napoleon (see his Réflexions relatives au sénatus-consulte du 28 floréal, an XII., 1804), and served the Restoration so faithfully that he was pardoned for having voted for the death of Louis XVI.

ISOBAROMETRIC (i′sô-băr’t-mět rik) LINES (from Gk. ioos, isos, equal + Eng. barometric, from Gk. Bápos, baros, weight + μerpov, metron, measure), or ISOBARS. Lines joining the places at which the atmospheric pressure reduced to a common level is the same. Ordinarily the weather maps show the isobars for sea-level, and by recent decisions of the International Meteorological Congress the barometric indications must also be corrected for the influence of the variations of gravity so that atmospheric pressures may all be expressed in uniform absolute measures. Formerly meteorologists avoided the troubles and uncertainties of the reduction to sea-level by using the departures of individual barometric readings from the normal reading of that instrument. These isabnormal lines were then plausibly converted into isobarometric lines by assuming that the normal pressure at sealevel was everywhere the same, namely, 760 millimeters, or 30 inches, and adding the departures from the normal algebraically to this assumed normal. The resulting pressures were assumed to represent closely the result that would have been given by reduction to sea-level. In 1857 Ferrel showed that the normal barometric pressure at sea-level could not possibly be uniform, but must be lower in the polar and higher in the tropical regions. In 1868 Buchan showed that the pressures are higher over the continents in the winter and over the oceans in the summer. Since these dates the importance of correct isobars based upon a correct method of reduction to sea-level has been more and more thoroughly appreciated.

The term 'isobarometric' was applied by Kaemtz, about 1830, to lines representing the oscillations of the barometer or its range from maximum to minimum during any month or year, but this usage is now obsolete. These oscillations are greatest in regions subject to the passage of severe and numerous storms. They are greater in the northern portion of the Atlan tic Ocean than in the southern portion or in corresponding latitudes on land.

The distance between two neighboring isobars is greater in proportion as the winds are less, and vice versa, the distance is small when the winds are strongest. The rate of change of pressure in a unit of horizontal distance is called the gradient of pressure. This barometric gradient inay be as large as 5 millimeters or 0.25 inch of barometric pressure per degree of a great circle when gales of wind prevail, and much greater in the narrow region around a storm centre within which hurricane winds prevail. The barometric gradients attending storm winds must not be considered as producing the winds. On the contrary, the winds have a great influence in producing the gradients, and much steeper ones would occur if the resistances to the motion of the wind did not prevent. Maps of isobars and gradients will be found in connection with the article on METEOROLOGY.

I'SOBU’TANE. See BUTANE AND ISOBUTANE. ISOCHEIMONAL (ist-kimô-nal) LINES. Lines that connect places having the same win ter temperature. See ISOTHERMAL LINES.

ISOCHRONISM, i-sõk'rô-nism (from isochronous, from Gk. iobxpovos, isochronos, equal in time, from loos, isos, equal + xpóvos, chronos, time). A pendulum is isochronous when its vibrations are performed in equal times, whether these vibrations be large or small; and it can possess this property by being constrained to move in a cycloidal arc. (See CYCLOID.) Huygens, who is believed to have first applied the pendulum to clocks (q.v.), made his pendulum isochronous by causing its string to wrap and unwrap itself round two equal cycloidal cheeks, the diameter of whose generating circle was equal to half the length of the pendulum. This device is no longer used, however, and isochronism is closely approximated in practice by causing the pendulum to describe a very small circular arc. The term is also used in connection with the balance of watches.

ISOCHRONOUS CURVE. See CYCLOID. ISOCLINAL, I'sô-kli'năl (from Gk. toos, isos, equal + kλivec, klinein, to incline), or ISOCLINIC LINE. An imaginary line on the earth's surface, such that at all points on it the 'dip' of a magnetic needle which is suspended free to turn in any direction is the same. (See MAGNETISM, TERRESTRIAL, where will be found maps showing isoclinals.) These lines are, in a general sense, parallel to the lines of equal latitude on the earth, but this is, of course, only a rough relation. At two points in the earth's surface the magnetic needle is supposed to point vertically downward. The positions now assigned these points, sometimes called the magnetic 'poles' of the earth, are latitude 70° 5' N., longitude 96° 43′ W., and latitude 73° 30' S., longitude 147° 30' W. The main agonic line (q.v.) passes through these poles.

ISOC'RATES (Lat., from Gk. 'Iookpáтns, Isokrates). Though one of the ten Attic orators of the Alexandrian Canon, Isocrates was rather a publicist and a pamphleteer than an orator. His long life (B.C. 436-338), as De Quincey interestingly expounds in his essay on Style, spans the century from Pericles to Alexander. In youth he was attached to the Socratic circle, and Plato in the Phædrus commends him above other orators for a certain touch of philosophy that

might lead to higher things. Elsewhere Plato seems to allude to him with irony as a rival teacher and the exponent of a competing ideal of culture. His first school, opened at Chios, was probably devoted to the professional rhetoric of the law courts, and he himself wrote forensic speeches, a few of which have been preserved, but which he was inclined to disavow in later days when his school at Athens came to represent what he regarded as the more broad and liberal training in essay-writing and epideictic (display) oratory on large political and Hellenic themes. From personal participation in the combats of the law courts or the assembly he was shut out by a weak voice and an invincible timidity. Isocrates stands for three things: (1) The idea that the Greeks should unite to conquer Persia. This is set forth in his most brilliant performance, the Panegyricus, which cost him ten years, and is supposed to have been published at Olympia in B.C. 380. Failing to influence Athens and Sparta, he appealed to individuals, Jason of Phere, the tyrant Dionysius, Philip of Macedon. The legend consecrated by Milton's sonnet that the "dishonest victory at Charonea, fatal to liberty, killed with report that old man eloquent," is sufficiently refuted by the tone of the letter to Philip. Indeed, the conquest of Asia by Alexander, though not accomplished by a union of Athens and Sparta, was in many ways a striking fulfillment of the prophecies of the Panegyricus. (2) Isocrates's ideal of culture as a faculty of elegant disquisition occupying the happy mean between the narrow utilitarianism of the advocate and the unprofitable subtleties of a Plato is to us, as exemplified in his writings, a ridiculous and platitudinous thing. But nevertheless his school did as much as the Academy of Plato to make the Athens of the fourth century the schoolmis

tress of Greece. Dissertations have been written about his pupils. From that school, says Cicero, as from the Trojan horse, a company of naught but chieftains issued forth. (3) Isocrates, though not himself a great writer, holds a great place in the evolution of European prose. He was a pupil of the brilliant Sophist Gorgias, who freely employed as ornaments of prose jingling assonance, alliteration, balanced antithesis of thought and expression, striking metaphor, and other rhetorical features of Greek poetry. Isocrates tempered the excess of these 'Gorgian figures,' but retained them so far as consonant with the genius of ornate but not extravagant prose. He also practiced and taught the smooth organic structure of the long rhythmical period, the avoidance of hiatus, the conscious variation of phrase and selection of synonym. These and many other traits of style employed by him in a mechanical and monotonous way were studied in him by the world's three great masters of prose, Plato, Demosthenes, and later, Cicero. And Cicero has made them the common property of all educated men in theory, if not in practice.

Isocrates's twenty-one orations and ten possibly genuine letters fill two small volumes of the Teubner texts. They have been partly translated into English by Freese (London, 1894), pt. i. They are not entirely free from dullness. There is an ample analysis and account of all of them in Jebb, Attic Orators, vol. ii. (London, 1876). That work and Blass, Attische Beredsamkeit (Leipzig, 1868-80; 2d ed., 1887-93), will

meet all the needs of the student. There is a good English annotated edition of the Panegyricus by Sandys, and selected orations have been edited with German notes by Schneider (Berlin, 1888).

I'SODIMORPHOUS SERIES. See ISOMOR

PHISM.

ISODYNAMIC (ï'sô-dî-năm'ik) LINES (Gk. loodúvapos, isodynamos, having equal power, from toos, isos, equal + dúvamus, dynamis, power, trom dúraobai, dynasthai, to be able). An imaginary line on the earth's surface, such that at each point on it the total magnetic force due to the earth has the same numerical value. This force is not a maximum at the magnetic poles; but there are two points in the Northern Hemisphere and two in the Southern, called 'foci,' at which the force is a maximum; that is, at each of these points the force is greater than for any point in the immediate vicinity.

ISOGAMY, î-sõg'a-mi (from Gk. toos, isos, equalyáμos, gamos, marriage). A condition in plants in which the pairing sex-cells (gametes) are similar, that is, they show no evident distinction into male and female. Only the lowest plants are isogamous. The contrasting term is heterogamy' (q.v.). See FERTILIZATION.

I'SOGE'OTHERMS. The name given to imaginary zones beneath the earth's surface passing through points of equal temperature.

ISOGONIC (i'so-gōn'ik) LINES (from Gk. toos, isos, equal + ywvla, gōnia, angle). Lines connecting those points on the earth's surface at which the deviation of the magnetic needle from the meridian, or the so-called magnetic declination, is the same. The isogonic lines, together with the isodynamic and isoclinic lines, when drawn on globes or maps, give a complete presentation of the magnetic state of the globe, as manifested at the earth's surface. These lines cover the globe in a rather irregular manner and vary in position, not only slightly from hour to hour and day to day, but quite appreciably from year to year, which latter changes are spoken of as the secular changes in terrestrial magnetism. A chart showing these lines will be found in the article on MAGNETISM, TERRESTRIAL, which should be read in this connection. See also DECLINATION and COMPASS.

ISOGONISM, î-sog'ô-nizm. See ISOMORPHISM. ISOLA BELLA, ĕ'zó-lå běl ́lå. One of the Borromean Islands (q.v.) in Lago Maggiore (q.v.), Italy.

ISOLA DEL LIRI, děl lẽ'rê. A city in the Province of Caserta, Italy, 96 miles northwest of Naples, on the rivers Liri (Liris) and Fibreno (Fibrenus), which furnish power for paper and woolen factories (Map: Italy, F 2). As the name indicates, the main town is on an island in the Liri, which has magnificent waterfalls 80 feet high. Half a mile beyond the picturesque estate of Count Balsorano are the twelfth-century Church of San Domenico and the tenth-century monastery where Gregory VII. was once a monk. The Isola San Paolo is supposed to be the Insula Arpinas, where Cicero was born. His ancestral villa here, which in the time of Domitian belonged to the poet Silius Italicus (q.v.), is described by him De Leg. 2, 3. Five miles west of Isola Del Liri is the thirteenth-century abbey of Santi Giovanni e Paolo di Casamari, now State

property. As an example of early Gothic it is rivaled in Italy only by the Convent of Fossanova in Sonnino (q.v.). The name Casamari commemorates the birthplace of Marius, who, like Cicero, made his home in the neighboring town of Arpino (q.v.)-ancient Arpinum. Isola has stone-quarries, and is lighted by electricity. Population (commune), in 1881, 6489; in 1901, 8202.

ISOLA GROSSA, grôs'så. A long and narrow island off the coast of Dalmatia, Austria. Area, 35 square miles (Map: Austria, D 5). It is poorly watered, but nevertheless produces southern fruits, such as grapes, olives, and figs. It has a population of over 3000, mostly Croats, and its chief town, Sale, has a harbor, a lighthouse, and a population of over 700.

ISOLA MADRE, mäʼdrâ. One of the Borromean Islands (q.v.) in Lago Maggiore (q.v.), Italy.

ISOLANI, ĕ'so-lä'nê, JOHANN LUDWIG HEKTOR, Count (1586-1640). An Imperial cavalry leader in the Thirty Years' War, born at Görz, of a noble Cypriot family. He was taken prisoner by the Turks in 1602; and after his escape became commander of a regiment of Croats. În 1632 he was put in command of all the Croatian forces; two years later he was made Count, after deserting Wallenstein. A clever leader of light

cavalry, and a terrible raider, Isolani fought in Picardy and Burgundy (1636), then in Hesse, Pomerania, and along the Upper Rhine against Guébriant.

ISOLATION (from isolate, from Fr. isoler, It. isolare, from ML. insulare, to separate, from Gk. Lat. insula, island, from in, in + salum, sea, cáλos, salos, surge). In evolution, the separation or segregation of any assemblage of plants or animals in a limited area, so that the incipient varieties or species are prevented from breeding with those of adjoining regions. Through such isolation the leveling effects of free crossing or mixing with allied varieties is prevented. Thus variations or nascent species become localized, with the result that there are many thousands of local races, varieties, and species.

Besides geographical isolation, there are other kinds of segregation. Darwin suggested two forms: (1) Arising from organisms breeding at slightly different seasons; (2) "from varieties of the same kind preferring to pair together." To the first of these may be added the inbreeding of butterflies of two different broods, a part of one brood being belated and flying with their 'nephews and nieces.' See DIGONEUTISM.

Lamarck was the first to broach the subject of the doctrine of isolation as a factor in speciesmaking in referring to man. Considering organisms in general, he points out that in reproductive unions the crossings between the individuals which have different qualities or forms are necessarily opposed to the continuous propagation of these qualities and their forms. He then instances man, and says that, if distance of habitation did not separate men, the intermixture by generation would cause the general characteristics distinguishing different nations to disappear. Wagner (1868) has fully proved by numerous examples the importance of migration and isolation in species-making. See MIGRATION, WAGNER'S LAW OF.

As a result of fifteen years' collecting in the Hawaiian Islands of land shells belonging mostly