ledons and dicotyledons (angiosperms) within a carpellary leaf which usually does not even open until the maturation of the fruit (see FRUIT), it is manifest that only those male spores (pollen grains) can be effective which are conveyed to the receptive surface (stigma) of the carpellary leaf, and there germinate until they succeed in penetrating as far as the ovule and embryosac. Hence the utility of wind or insects for the transport of pollen. In this regard it is evident that the help of spore-eating insects might early have been of service, since spores might readily thus be conveyed adhering to their bodies. It has been already noted (see CHLOROPHYLL) that the colouring matter of flowers, like that of vernal and autumnal leaves, may be associated with phases in the constructive or destructive changes of chlorophyll. Since the reproductive process especially checks those of vegetation, we have here an agency for the production of floral colour, which, by rendering the reproductive shoots more conspicuous to insects, would be constantly aided by natural selection. Upon the latter process, indeed, the customary explanation of the origin of floral colour and markings solely depends. An analogous advantage for the attraction of insects would be given by the overflow as 'nectar' of any excess of the sugary sap so largely used up by the flower itself, or similarly by the disengagement of perfume. A constant adaptation between flower and insect being in such ways established, further specialisations arise. Thus, while in many flowers-e.g. crucifers, the stamens and stigmas are ripe simultaneously, a want of time-keeping' is frequently observed, the stamens becoming protandrous-i.e. ripening before the stigmas, as typically in Geranium (q.v.), so that self-fertilisation is impossible, and a physiological separation of the sexes (dichogamy) is thus insured. Or where the ripening remains simultaneous, two or even three forms of flower (dimorphism, trimor. phism) may occur in different individuals of the same species, so rendering cross-fertilisation by insects indispensable (see PRIMROSE, LOOSESTRIFE). The individual flower may also become peculiarly specialised thus, the nectary may become so deep as to be accessible only to insects with long proboscis, as bees to the exclusion of flies, butterflies and moths to the exclusion even of bees, it may be even to some particular species only. Birds, too, may replace insects (see HUMMING-BIRD, HONEY. BIRD). Mechanical adjustments are also to be found in many of the more specialised types, witness the stamens of the sage, which are rocked forward by the bee on entering the flower so as to dust his back with pollen just where it will be rubbed off upon the stigma of another flower. The most extraordinary variety and complexity is, how ever, that presented among the Orchids (q.v.).

:

How some flowers (e.g. Stapelia, Rafflesia) attract the services of flesh-flies by the odour and even colour of carrion; how others like Arum and Aristolochia may entrap and detain the fertilising insect until well dusted with pollen, are examples which can but be mentioned. Nor can we describe the defences of flowers from rain or from ants, &c. (see, however, CATCHFLY, HEATH, &c.).

In wind-fertilised plants the flowers are usually comparatively small and inconspicuous, but numerous and closely aggregated, often in spikes, heads, or catkins; the floral envelopes are usually small and greenish; one or both whorls are indeed frequently absent (Incomplete). The stamens are few but often versatile as in grasses, the ovary reduced, commonly only one-seeded, but with one

or

more styles and stigmas, the latter often exuberantly branched or feathery, so catching the small pollen-grains. The stigmas are ready before the pollen is shed (protogynous dichogamy);

and flowering often takes place as in many foresttrees before the development of the leaves. The pollen grains may be lightened with air-sacs as in the pine, may be helped by gravitation as in maize and bulrush, where the male inflorescence grows higher than the female, or may be scattered explosively as in the nettle or artillery plant. The utility of all these special characters of wind-fertilised flowers is thus no less obvious than that of the peculiarities of those dependent upon the visits of insects, and the natural selectionist is hence accustomed to draw from both of these remarkable sets of adaptations many of his strongest arguments for the development of even the most complex organic structures through the cumulative selection of minute spontaneous varieties (see DARWINIAN THEORY). Some facts, however, such as the repeated development of the characters of wind-fertilised flowers in quite unrelated types, seem rather to indicate the possibility of a constitutional interpretation similar to that indicated on the previous page (see VARIATION).

It is thus manifest that the flowers of every species in nature thus invite and reward an ob servant interest far other than that of the mere collector, systematist, or even morphologist. Further information will sometimes be found under individual headings-e.g. CAPRIFICATION, GERANIUM, VALLISNERIA, &c.

See Müller's Fertilisation of Flowers (trans. 1882); Knuth's Handbook of Floral Pollination (1906-8); Kerner's Natural History of Plants (trans. 1902); Henslow's The Origin of Floral Structures through Insects and other Agencies (1888), and The Making of Flowers (1891); Eichler's Flower Diagrams; several of Darwin's works; also VEGETABLE PHYSIOLOGY, and books there noted.

Flower, SIR WILLIAM HENRY, K.C.B. (1892), was born at Stratford-on-Avon in 1831, served as assistant-surgeon in the Crimea, and afterwards became demonstrator of anatomy at the Middlesex Hospital. He was appointed in 1861 conservator of the Hunterian Museum, in 1869 Hunterian professor of Comparative Anatomy and Physiology, and in 1884-98 was director of the natural history departments of the British Museum. F.R.S., LL.D., and president of the British Association (1889), he wrote on human nerves (1861), on the osteology of the mammalia (3d ed. 1885), on the horse, on museums, on the Monotremata and the marsupials, and on the brain of apes and lemurs. He died 1st July 1899. See Life by Cornish (1904).

Flower-de-luce, the old name for the common species of Iris (q.v.), or for the heraldic emblem conventionalised therefrom. See FLEUR-DE-LIS.

Flowering Currant, an ornamental shrub, Ribes sanguineum, whose flowers change from white to pink. See RIBES.

Flowering Plants. See PHANEROGAMIA, and articles there referred to.

Flowering Rush (Butomus umbellatus), a order Alismaceæ, easily recognised by its large linear monocotyledonous plant usually reckoned under the three-edged leaves (which are said to cut the mouths of cattle, whence the Greek form of the generic name), and by its umbel of rose-coloured flowers, which Ovid tells us render the plant a special favourite of Flora. The bitter rootstock was forparts of eastern Europe) as a source of starchy flour, merly officinal, and was also used (as still in some and the leaves are sometimes plaited. It is not uncommon in ponds and wet places, and is well worth introduction where such conditions are present. Flowerless Plants. See CRYPTOGAMIA, and articles there referred to.

Flower-lore. See PLANT-LORE.

Flower of Jove (Agrostemma flos-Jovis), a pretty caryophyllaceous plant, with heads of purple

or scarlet flowers, and leaves silky white with hairs. Other species are common in gardens-e.g. A. cœlirosa (Rose of Heaven), and A. coronaria. The genus, also known as Rose campion, owes its technical name to the ancient use of the flowers in crowns and garlands.

Flower-pots are utensils of culture whereby plants are rendered portable at all seasons. They are used in one form or another in all countries where gardening as an art is practised. In Britain and on the Continent they are made in all sizes, from the thumb-pot of 2 inches in depth used for potting tiny seedlings and delicate cuttings, to extra large ones of 3 feet to accommodate large palms, tree-like camellias, &c. Their diameter is usually equal to their depth. They are glazed or unglazed, it being immaterial to their utility whether they are so or not; and are plain or ornamental and artistic according to taste and the purpose for which they are intended. In order to be healthy receptacles for the roots of plants, they must be provided with perforated bottoms to admit of the free egress of water from the soil. Saucers are made for all ordinary sizes of flower-pots for use in rooms and other places where drip would be inconvenient or undesirable.

Flowers, in Chemistry, is a term originally given by the alchemists to the sublimates which arose, or appeared to grow, from certain bodies capable of undergoing volatilisation when subjected to heat; thus, flowers of antimony, flowers of arsenic, flowers of benjamin or benzoin, flowers of sulphur, flowers of zinc, &c. See ANTIMONY, &c. The word is also applied to fungous growths, as flowers of tan. See MYXOMYCETES.

Flowers, FLORISTS', are those numerous forms of flowering plants which, having an inherent tendency to vary in the colour and size of their flowers and in habit when reared from seed, have received special attention in cultivation and in selection with the view of bringing their floral qualities up to ideal standards of excellence formed by the common consent of florists for each particular variety. Thus, for instance, the pansy, one of the most familiar of florists' flowers, is in all its wonderful variety the progeny of Viola tricolor, a widely distributed native of Britain. Its natural tendency to seminal variation rendered it a very facile subject in the hands of the florist, as may be seen by comparing the puny, unequal, and flabby flowers of the natural forms of the species with the large, circular, substantial, and brilliantly coloured blooms of the florists' varieties. This has been achieved by the intelligent application of the principle of selection, the object being the attainment of a given ideal respecting the size, form, substance, and colour of the flowers. The petals are the only parts affected in this case; they are enlarged in breadth and length, their substance or thickness is increased, and their outline is rendered more symmetrical, but the other organs of the flower are not changed. As with the pansy, so it has been with every other kind of plant bearing single flowers in the florists' category. It is different with those kinds whose flowers are double, such as the carnation, anemone, hollyhock, ranunculus, rose, &c. these the essential organs of the flowers have been wholly or partially metamorphosed into petals. But the so-called double flowers of dahlias, chrysanthemums, and other forms of the natural order Compositæ are not really double in this sense; the fertilising organs are not changed to petals in their case; but the tubular florets of the disc assume the strap-like shape of those of the ray, and hence the semblance of double flowers in such

cases.

In

The Dutch were the first among European nations to cultivate systematically florists' flowers: to them is due the merit of having brought the Tulip (q.v.), the hyacinth, the anemone, the ranunculus, and the rose to the high degree of perfection their numerous varieties now present. The French florists have also had a large share in the improveBritish ment of the three last-named classes. florists have distinguished themselves more particularly in the production of auriculas, polyanthus, the phlox, pentstemon, carnation, pink, hollyhock, dahlia, pansy, pelargonium, &c. But the Chinese and Japanese appear to have fostered the culture of many flowers in the same way as the European florists, long prior to the latter having done so. Camellias, azaleas, and tree-peonies were some of their favourite florists' flowers long before Europeans had much intercourse with the Chinese.

New varieties are obtained chiefly from seeds, but some also are obtained by sports, which, in the language of the florist, mean freaks of nature. Thus, the flowers on a certain shoot of a plant may perhaps exhibit features of a kind novel and distinct from those of the parent, and the variety, if worthy of being perpetuated, is propagated by cuttings or by grafting, according to the mode best adapted to the kind. If the variation becomes fixed or permanent a new sort is thereby obtained without direct seminal intervention; but this does not always follow, although a keen florist will never allow such an opportunity to escape without an attempt to improve it. Varieties of special merit in any class of florists' flowers can only be perpetuated by cuttings, layering, grafting, or division, because they cannot be relied upon to reproduce themselves from seed.

After

Fludd, ROBERT, an English physician and mystic, born at Milgate in Kent in 1574. studying at Oxford, he spent some years travelling on the Continent, where he became acquainted with the writings of Paracelsus. On his return to England he settled as a physician in London, where he died in 1637. Fludd (Lat. De Fluctibus) was the author of a theosophic system, the distinguishing features of which were the conception of man, the microcosm, as an analogy, in a physico-spiritual sense, of the universe or macrocosm, and the belief that the laws of the physical universe were dominated by two fantastic principles called the northern or condensing power,' and the 'southern or rarefying power. His views called forth adverse criticisms from Gassendi, Kepler, and others.

Flue. See CHIMNEY, WARMING.
Flüelen. See LUCERNE (Lake of).

Flügel, JOHANN GOTTFRIED, German lexicographer, born at Barby in 1788, travelled as a merchant to North America, and in 1824 was appointed lector of the English language at Leipzig, where in 1838 he became United States consul, and in 1848 agent in Germany for the Smithsonian Institution. He died 24th June 1855. He prepared a standard dictionary of English and German (1830; 4th remodelled edition, by his son Felix, 1891). His son professor of English Philology in Stanford UniverEwald Flügel (1863-1914), born at Leipzig, was sity, and began a Chaucer Lexicon.

Fluid. In a solid body the constituent particles never move far from a certain position of equilib rium. In a fluid the particles can move about with greater or less freedom from one part of the body to another. All liquids, vapours, and gases are therefore known as fluids. All fluids are perfectly elastic; but liquids are highly incompressible, while gases can easily be compressed. In every actual fluid there is more or less frictional resistance to the molecular motions; but it is often advantage

ous to consider theoretically the properties of frictionless, or, as they are called, 'perfect' fluids. There is no sharp distinction between the solid state and the liquid state. Much depends upon external circumstances, such as temperature or the intensity of gravity. Some substances splinter under the action of sudden intense stress, while they flow like viscous liquids when exposed to long-continued gentle stress.

Fluke (Fasciola (or Distomum) hepatica), the parasitic worm which causes the liver-rot' of sheep. It belongs to the class of Trematodes (q.v.), and to a large genus of about three hundred species, if the two titles Fasciola and Distomum be regarded as identical. The adult fluke, which occurs in numbers in the bile duct of the sheep and other domestic animals, has a flat, oval, or leaf-like appearance, the broader end being anterior. It usually measures nearly an inch in length by half an inch across at its broadest part. The colour varies

or

from reddish-brown orange at the sides, to grayish-yellow, sometimes with dark spots, in the middle. There are two suckers, as the word Distomum suggests-one at the head end, perforated by the mouth; the other imperforate, on the ventral surface, also in the middle line, a little farther back. The food is blood sucked in from the liver. The Fasciola hepatica, from internal structure is comthe ventral surface (after plex. There is a much Sommer): branched blind alimentary The alimentary and nervous canal penetrating the whole systems only are shown on animal, which is without the left of the figure; the any distinct body-cavity; the right side; a, right the nervous system is a main division of the ali- ring round the pharynx, mentary canal; c, lateral with nerves running fore ganglion; d, lateral nerve; and aft; there are no sense e, mouth; 9, ventral sucker. organs, though the larva has eye-spots to start with; the muscular system is well developed; the excretory system consists of two very much branched vessels opening at a posterior pore; the reproductive system is hermaphrodite and complex.

excretory system alone on

Life-history. The history of the fluke is happily an intricate one and full of hazards. The ova are probably fertilised by male elements from the same animal, a very unusual occurrence, all but exclusively restricted to certain parasitic flat-worms. The eggs are furnished with nutritive capital from a yolk gland, are surrounded by a shell, and begin to develop a little within the parent animal. After extrusion from the latter they may be found in the bile ducts in enormous numbers, each fluke being said to produce about fifty thousand. Such prolific multiplication is a very frequent characteristic of parasitic animals, and is probably associated with the abundant and at the same time stimulating food. Its utility in securing the continuance of the species in face of the numerous risks of failure

is obvious. From the bile duct of the sheep the segmented ovum enclosed in its shell passes to the exterior. The embryo develops for two or three weeks, and the successful result eventually becomes free in water. In swims for some hours by means of a covering of cilia, but its sole chance of life

appears to lie in meeting and attaching itself to a small water-snail (Limnæus truncatulus), into which it bores its way. Having established itself, the embryo fluke loses its cilia, and is metamorphosed into what is called a sporocyst. This may divide transversely into two; but usually certain cells within the sporocyst behave like parthenogenetic ova, and develop into a fresh generation or several generations known as redia. The rediæ burst out of the sporocyst, and migrate into the liver or some other part of the snail, killing their host if they are very numerous. Like the sporocyst, they give rise internally to more embryos, of which some may be simply rediæ over again, while others develop into tailed embryos or cercaria. These emerge from the redia, wriggle out of the snail, swim freely in the water, climb up grass stems or such like, swing their tails off, and encyst. If the encysted cercaria on the grass stem be eaten by a sheep it grows into the adult and sexual fluke. To recapitulate, the developing embryo becomes a free-swimming form; this bores into a snail and changes into a sporocyst; from certain cells of the latter asexual rediæ arise; these eventually give origin in a similar way to tailed cercaria, which, eaten by a sheep, grow into flukes. There are thus several asexual generations interrupting the ordinary sexual process, illustrating what is known as 'alternation of generations. After reproduction the adult flukes may die in situ or may migrate from the liver and pass out of the sheep. The life-history was independently worked out by Leuckart and Thomas.

Practical Importance.-The disease of liver-rot in sheep is widespread and disastrous, sometimes killing a million sheep in a year in the United Kingdom. But it is no longer so serious as it used to be. It is especially common after wet seasons, and in low, damp districts. The external symptoms are described as 'emaciation, tenderness in the loins, harshness and dryness of the wool, and a scaly condition of the skin.' A swelling (watery poke') below the lower jaw is very diag nostic. The preventives suggested are drainage of pastures and dressings of lime or salt; destruction of eggs, infected manure, and badly fluked sheep; giving the sheep salt and a little dry food. The same fluke sometimes occurs in horse, deer, goat, pig, and rarely in man. Many other species and related genera are likewise of serious importance as parasites. See also ANCHOR, FLOUNDER.

See PARASITISM, TREMATODE, BILHARZIA; also Leuc kart, Parasiten des Menschen (1863; new ed. 1879 et seq., trans. by Hoyle); Thomas, Quart. Jour. Micr. Sci. XXIII. (1883); Braun, Animal Parasites (trans. 1906). Fluorescein. See DYEING.

Fluorescence is the term applied to a peculiar blue appearance exhibited by certain substances exposed to sunlight, and especially observable in a dilute solution of sulphate of quinine. See PHOS.

PHORESCENCE.

com

Fluorine (sym. F, eq. 19) is an elementary substance allied to chlorine. Its principal natural source is the mineral fluor spar, CaF, although it is also found in minute quantities in the igneous rocks, natural waters, plants, the bones and teeth of animals, as also in milk, blood, &c. All attempts to isolate fluorine in vessels of glass, gold, platinum, &c. long failed, owing to its powerful action on these substances and its readily forming pounds with them. But in 1888 it was obtained pure in a vessel made of an alloy of platinum and iridium; and in 1893 Moisson again isolated it. It is a gas with properties like those of chlorine, but differing in energy of action. The compounds important. Hydrofluoric acid, HF, is generally prepared by heating gently in a lead still a mixture of one part

of fluorine are not numerous, but are

of fluor spar, CaF2, with two parts of sulphuric acid, H2SO4, when the vapours of hydrofluoric acid, HF, are evolved, whilst sulphate of lime, CaSO4, is left in the still. The dense acid vapours are conducted through a lead pipe into a lead receiver or bottle surrounded by a freezing mixture of ice and common salt. The acid is generally mixed with water when desired to be kept for some time. When the most concentrated hydrofluoric acid is required, the still and receiving vessel must be made of platinum. The other metals are not suitable for such apparatus, as they are rapidly corroded by the acid. When prepared in its strongest form, hydrofluoric acid has the density of 1060, and is a colourless, fuming liquid of great volatility, which boils at 67° (19.4° C.). Not only does hydrofluoric acid corrode and dissolve the ordinary metals (excepting lead and platinum), but when placed on the skin it produces a severe burn owing to its caustic nature. The most important property which hydrofluoric acid possesses is its power of eating into and dissolving glass, which admits of its application in the etching of characters upon glass, as in thermometer tubes, and for eating away greater or less thicknesses of plates or sheets of coloured glass, so as to produce a variety of shades. See GLASS, and GLASS-PAINTING. The acid may be kept without any difficulty in bottles made either of paraffin-wax or gutta-percha.

Fluorotype, a photographic process, suggested by Robert Hunt in 1844, in which salts of fluoric acid were employed; but, as the impression was not very strong, the plate had to be afterwards steeped in a weak solution of proto-sulphate of iron.

Fluor Spar (FLUORITE, BLUE JOHN, DERBYSHIRE SPAR) is the only common mineral in which fluorine is present in any large proportion. The fluorine is combined with calcium, and forms calcium fluoride, CaFl, consisting of 48 9 calcium and 511 fluorine; occasionally it also contains some calcium chloride, and now and again organic matter, which is sometimes so abundant that when the mineral is struck with a hammer it emits a fetid odourhence the name fetid-spar (Ger. stink-fluss). Fluor spar occurs both crystallised and massive, the massive varieties exhibiting a crystalline structure; the crystals appear usually in groups, sometimes of the primary form, which is a cube, but often of secondary forms, of which there is great variety, as the octahedron, rhombic dodecahedron, &c. Fluor spar is sometimes colourless, but often green, blue, yellow, or red, more rarely gray, or even black different shades of colour frequently appearing in the same specimen, and in the massive varieties beautifully intermixed. Its colours often rival those of the most beautiful gems; but it is of very inferior hardness, being scratched even by quartz. Its specific gravity is 3-15 to 3:20. It generally becomes phosphorescent when heated, although this is more remarkably the case with some varieties than with others; it is decomposed by heated sulphuric acid, with evolution of hydrofluoric acid as a pungent gas; and, this having the property of acting upon and corroding glass, fluor spar is used with sulphuric acid for etching on glass. Fluor spar is also used for ornamental purposes, being wrought into vases, &c., for which it was in high esteem among the ancients. But the greater abundance in which it is now obtained has diminished the value of ornaments made of it. It is very commonly associated with ores of tin, silver, lead, and copper, occurring chiefly in veins, but is also found by itself in drusy cavities in granite and in veins in crystalline schists, slate, limestone, and sandstone. It has been met with also in volcanic tuff in Italy and in cannel-coal in the United States, where it occurs in Illinois, Jefferson Co., N. Y.,

Flushing (Dutch Vlissingen), a strong fortress and seaport of the Netherlands, in the province of Zealand, is situated on the south coast of the island of Walcheren, at the mouth of the Western Scheldt, which it commands. Formerly an important naval station, it was converted into a commercial harbour in 1865-73, and carries on an active trade with Java, England, and South America. A daily service of steamers connects Flushing with Queenborough (Kent) in England. There are outer and inner harbours, and, since 1875, a large floatingdock. Doubling of the harbour accommodation began in 1920. The inhabitants (22,500) are occupied mainly in shipping pursuits. Shrimps are taken. The town capitulated to the Earl of Chatham in 1809.

Flushing, formerly a post-village of Queens county, New York, but since 1897 included in the City of New York. It is situated on Flushing Bay, a branch of the East River.

Flustra, or SEA-MAT (q.v.), one of the commonest genera of marine Polyzoa (q.v.).

Flute (Fr. flute, Ger. flöte, Ital. flauto), one of the oldest of wind-instruments, which originally had several varieties: one, in more modern times called flûte à bec, now developed into the Flageolet (q.v.); another, which was sounded by means of a hole in the side like the modern flute; and a third, used by the ancient Egyptians, in which the sound was produced by blowing into the open end of the tube. A modification of this last instrument is used still by the peasantry along the Nile.

The modern cone-bore flute consists of a tapered tube, in which the sound is produced by blowing with compressed lips into a large orifice near the top or wider end, which is stopped with a cork. Six holes in the lower end, to be covered by the first three fingers of both hands, serve to make the scale, supplemented by keys numbering from one to fourteen. The flute is what is called an octavescaled instrument-i.e. by covering all the holes and lifting the fingers one by one in regular order, beginning at the bottom, the notes from D below the stave to C are made; then, by repeating this process and blowing a little sharper into the mouth aperture, the same notes, an octave higher, are produced. Another octave can be produced by crossfingering, the total compass being about three octaves. Two additional keys at the bottom of the tube, worked by means of levers by the little finger of the right hand, give the notes Čand C below the stave.

The faults of this flute are that, as the holes must be placed where the fingers can reach them, they are not always in the exact places to be perfectly in tune, and the notes are not equal in quality. To meet these defects the flute has undergone more changes and improvements in modern times than any other musical instrument. The most important of these have been the cylinder bore and the system of fingering introduced by Theobald Boehm in 1832, and patented in England by Rudall and Rose in 1847. The modern cylinder flute, from the head downwards, is cylindrical, or all one width of bore, while the head-piece has a slight parabolic taper, and when combined with the Boehm finger

ing it forms a nearly perfect instrument, with all the notes in tune and of practically equal quality of tone. The holes are placed where they make the correct notes, and to facilitate manipulation they are stopped by means of keys which can be worked conveniently by the fingers. The fingering of the scale on the Boehm flute is quite different from the

ordinary flute; and many other modified systems, more or less founded on the old, have been devised, among which may be mentioned those of Siccama, Clinton, and Carte. It would occupy too much space to describe their methods in detail. The general appearance of the Boehm cylinder flute may be seen in the figure.

Flutes are usually made in cocoa-wood, ebonite, silver, and gold, and vary in price from a shilling or two to about £180 for one made in 18-carat gold. The Boelim flute is very often made in silver, which is easily sounded and gives a fine liquid tone; it costs about 30 guineas. The ordinary cocoa or ebonite Boehm flute costs from 18 to 30 guineas, according as it is mounted in German silver or silver. Except for military flutes, which are still made conical, the cylinder has almost completely superseded the cone bore.

The flute described above is what is known as the concert flute; but flutes are also made in a variety of smaller sizes for various purposes in E, F, Bb, and C; there are also D, E, and F piccolos or octave flutes, which are much used in modern orchestral music. In construction, however, they are all much alike, and need not be further described. A bass flute, too, is sometimes used, the Boehm variety being simply a large flute, 32 inches long and 1 inch in diameter, and having a compass from the upper G of the bass stave upwards. Also, see FIFE.

The concert flute, from the sweetness of its tone and the comparative simplicity of its execution, is extremely popular as an amateur instrument, and a great variety of music is published arranged for flute and pianoforte; and, as it plays the same notes as the voice and piano, it can be made useful in all kinds of music. The flute is made great use of in classical music; Bach, Haydn, Handel, Mozart, Beethoven, Mendelssohn, and all the later writers giving it a leading part in their works; while Quantz, Kuhlau, and many others devoted themselves almost speci ally to writing for it. See T. Boehm's Essay on the Construction of Flutes, and C. Welsh's History of the Boehm Flute.-The so-called 'flute-stop' is one of the many stops of the Organ (q. v.).

Flute-mouths (Fistularida), a family of marine fishes, nearly allied to sticklebacks, remarkable for the elongation of the front bones of the head into a pipe bearing the small mouth at its apex. They live near the shore, and are widely distributed in the warm parts of the Atlantic and Indo-Pacific. There are but few species-e.g. Fistularia tabaccaria, and Aulostoma chinense. The Snipe-fish or Trumpet-fish (q.v., Centriscus scolopax) belongs to an allied family (Centriscidae). Fluting, the mouldings in the form of hollows or channels cut vertically on the surface of columns. The idea is supposed to have been originally derived from the bundles of reeds tied together which formed the early columns of the Egyptians. Flutes were adopted by the Greeks as ornaments to their Doric, Ionic, and Corinthian columns, and were retained by the Romans in their architecture. The

These curves are supposed, in Greek Doric, to be elliptical, and they are carried up across the necking to the base of the cap. In the other styles there are twenty-four flutes on the circumference (fig. 2). These are semicircular and separated by a small fillet, and, before reaching the necking and the base, are terminated with semicircular top and bottom.

Flutes are said to be cabled when they are filled in to about one-third of their height from the base with a convex bead. This is done to strengthen the column and protect the flutes. In countries where Roman remains are abundant, as in the south of France, fluting was sometimes adopted by the early medieval architects, as at Arles and Autun. In Italy also traces of this decoration are visible during the middle ages; but the flutes are not limited to the vertical form-in Romanesque Architecture (q.v.) they assumed many varieties of forms, such as curves, zigzags, &c., twisting round the shafts.

Flux (Lat. fluxus, from fluo, 'I flow '), a discharge generally from a mucous membrane. The term is applied more or less frequently to all preternatural fluid evacuations from the body, but especially to those from the bowels and from the uterine organs. Dysentery (q.v.) was long termed the bloody flux to distinguish it from simple diarrhoa. See also CATARRH, DISEASE, MEDICINE.

Flux is the term given to the substances employed in the arts to assist the reduction of

a metallic ore and the fusion of the metal. White flux is an intimate mixture of ten parts of dry carbonate of soda and thirteen parts of dry carbonate of potash, and is mainly instrumental in removing siliceous impurities by combining with the silica to form a fusible glass; black flux is prepared by heating in close vessels ordinary cream of tartar (bitartrate of potash), when an carbonate of potash is obtained. The latter flux, intimate mixture of finely-divided charcoal and when mixed with finely-divided metallic ores, and the whole raised to a high temperature in a furnace, not only is useful in removing the silica by the action of the carbonate of potash as above described, but the charcoal withdraws the oxygen from the metallic oxide and causes the separation of the pure metal. For economy, limestone is employed in the smelting of iron ores. Fluxes are also employed in the operations of brazing and soldering to keep the surfaces to be joined free from oxide. Fluor spar, borax, protoxide of lead, and other basic substances are also used for fluxing. See IRON AND STEEL, COPPER, &c.

Fluxions. The method of fluxions and fluents was the name given after Newton to that branch of mathematics which with a different notation is known after Leibniz as the differential and integral calculus. Newton, representing quantities in the manner of Euclid and others by lines, looked upon