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between the effects of external pollen and that from the same flower.

Cross-pollination may occur between two flowers on the same plant (geitonogamy) or between flowers on distinct plants (xenogamy). The former, which is a somewhat less favourable method than the latter, is effected by air-currents, insect agency, the actual contact between stigmas and anthers in neighbouring flowers, where, as in the family Compositae, flowers are closely crowded, or by the fall of the pollen from a

Long

styled.

Mid

styled.

Shortstyled.

(From Darwin's Different Forms of Flowers by permission.)

FIG. 2.-Diagram of the flowers of the three forms of Lythrum salicaria in their natural position, with the petals and calyx removed on the near side. (X 6 times.)

The dotted lines with the arrow show the directions in which pollen must be carried to each stigma to ensure full fertility.

higher on to the stigmas of a lower flower. Anton Kerner has shown that crowded inflorescences such as those of Compositae and Umbelliferae are especially adapted for geitonogamy. Xenogamy is of course the only possible method in diclinous plants; it is also the usual method in monoclinous plants, owing to the fact that stamens and carpels often mature at different times (dichogamy), the plants being proterandrous or proterogynous. Even in homogamous flowers cross-pollination is in a large proportion of cases the effective method, at any rate at first, owing to the relative position of anther and stigma or the fact that the plant is self-sterile.

The subject of heterostyly was investigated by Darwin (see his Forms of Flowers) and later by Hildebrand. In the case of dimorphic flower, such as Primula, four modes of pollination are possible, two distinguished by Darwin as legitimate, between anthers and stigmas on corresponding levels, and two so-called illegitimate unions, between anthers and stigmas at different levels (cf. fig. 1). In a trimorphic flower such as Lythrum salicaria there are six possible legitimate unions and twelve illegitimate (see fig. 2). Experiment showed that legitimate unions yield a larger quantity of seed than illegitimate.

Many plants produce, in addition to ordinary open flowers, so-called cleistogamous flowers, which remain permanently closed but which notwithstanding produce fruit; in these the corolla is inconspicuous or absent and the pollen grows from the anther on to the stigma of the same flower. Species of Viola (see fig. 3), Oxalis acetosella (wood sorrel) and Lamium amplexicaule are commonly occurring instances. The cleistogamous flowers are developed before or after the normal open flowers at seasons less Sfavourable for cross-pollination. In some cases flowers, which open under normal circumstances, remain closed owing to unfavourable circumstances, and self-pollination occurs as in a

FIG. 3.

st.

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Cleistogamous

typical cleistogamous flower-these flower of Viola sylvatica. have been distinguished as pseudo1, flower X 4. 2, flower more highly cleistogamous. Instances Occur in magnified and cut open. water plants, where flowers are un- a, anther; s, pistil; able to reach the surface (e.g. Alisma st, style; v, stigmatic natans, water buttercup, &c.) or surface.

where flowers remain closed in dull or cold weather.

Systems of classification of flowers according to the agency by which pollination is effected have been proposed by Delpino, H. Müller and other workers on the subject. Knuth suggests the following, which is a modification of the systems proposed by Delpino and Müller.

A. Water-pollinated plants, Hydrophilae. A small group which is subdivided thus:

a. Pollinated under the water; e.g. Najas where the pollen grains are rather heavier than water, and sinking down are caught by the stigmas of the extremely simple female flowers. b. Pollination on the surface, a more frequent occurrence than (a). In these the pollen floats on the surface and reaches the stigmas of the female flowers as in Callitriche, Ruppia, Zostera, Elodea. In Vallisneria (fig. 4) the male flowers become detached and float on the surface of the water; the anthers are thus brought in contact with the stigmas of the female flowers.

B. Wind-pollinated plants, Anemophilae.-In these the pollen grains are smooth and light so as to be easily blown about, and are produced in great quantity; the stigmas are brush like or feathery, and usually long and protruding so as readily to catch the pollen. As no means of attraction are required the flowers are inconspicuous and without scent or nectar. The male inflorescence is often a pendulous catkin, as in hazel and many native English trees (fig. 5); or the anthers are loosely fixed on long thread-like filaments as in grasses (fig. 6).

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A, female flower; s, stigmas.

B, male flowers; I before; 2, after spreading of the petals. A male flower has floated alongside a female and one of its anthers, which have opened to set free the pollen, is in contact with a stigma. a, anther.

C. Animal-pollinated plants, Zoidiophilae, are subdivided according to the kind of animal by agency of which pollination is effected, thus:

a. Bat-pollinated, Chiropterophilae. A Freycinetia, native of Java, and a species of Bauhinia in Trinidad are visited by bats which transfer the pollen.

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FIG. 6.-Grass Flower showFIG. 5. Catkin of Male ing pendulous anthers and proFlowers of Hazel. truding hairy stigmas. c. Snail or slug-pollinated flowers, Malacophilae.-In small flowers which are crowded at the same level or in flat flowers in which the stigmas and anthers project but little, slugs or snails creeping over their surface may transfer to the stigma the pollen which clings to the slimy foot. Such a transfer has been described in various Aroids, Rohdea japonica (Liliaceae), and other plants.

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aid is sought, and there are also numerous devices for protecting the pollen and nectar from rain and dew or from the visits of those insects which would not serve the purpose of pollen-transference (unbidden guests). The following subdivisions have been suggested

A. Pollen Flowers.-These offer only pollen to their visitors, as species of anemone, poppy, rose, tulip, &c. They

are simple in structure and regular in form, and the generally abundant pollen is usually freely exposed.

B. Nectar Flowers.-These contain nectar and include the following groups:

1. Flowers with exposed nectar, readily visible and accessible to all visitors. These are very simple, open and generally regular flowers, white, greenish-yellow or yellow in colour and are chiefly visited by insects with a short proboscis, such as short-tongued wasps and flies, also beetles and more rarely bees. Examples are Umbelliferae as a family, saxifrages, holly, Acer, Rhamnus, Euonymus, Euphorbia, &c.

2. Flowers with nectar partly concealed and visible only in bright sunshine. The generally regular flowers are completely open only in bright sunshine, closing up into cups at other times. Such are most Cruciferae, buttercups, king-cup (Caltha), Potentilla. White and yellow colours predominate and insects with a proboscis of medium length are the common pollinating agents, such as short-tongued bees.

3. Flowers with nectar concealed by pouches, hairs, &c.
Regular flowers predominate, e.g. Geranium, Cardamine
pratensis, mallows, Rubus, Oxalis, Epilobium, &c., but
many species show more or less well-marked median
symmetry (zygomorphism) as Euphrasia, Orchis, thyme,
&c., and red, blue and violet are the usual colours.
Long-tongued insects such as the honey-bee are the
most frequent visitors.

4. Social flowers, whose nectar is concealed as in (3), but the
flowers are grouped in heads which render them
strikingly conspicuous, and several flowers can be simul-
taneously pollinated. Such are Compositae as a class,
also Scabiosa, Armeria (sea-pink) and others.
5. Hymenopterid flowers, which fall into the following groups:
Bee-flowers proper, humble-bee flowers requiring a
longer proboscis to reach the nectar, wasp-flowers such
as fig-wort (Scrophularia nodosa) and ichneumon
flowers such as tway-blade (Listera ovata).

The shapes and colours are extremely varied; bilaterally symmetrical forms are most frequent with red, blue or violet colours. Such are Papilionaceous flowers, Violaceae, many Labiatae, Scrophulariaceae and others. Many are highly specialized so that pollination can be effected by a few species only. Examples of more special mechanisms are illustrated by Salvia (fig. 9). The long connective of the single stamen is hinged to the short filament and has a shorter arm ending in a blunt process and a longer arm bearing a half-anther. A large bee in probing for honey comes in contact with the end of the short arm of the lever and causes the longer arm to descend and the pollen is deposited on the back of the insect (fig. 9, 1). In a later stage (fig. 9, 2) the style elongates and the forked stigma occupies the same position as the anther in fig. 9, I.

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(From a drawing in the Botanical Gallery at the British Museum.)

FIG. 7.-Flower of Datura sanguinea visited by humming-bird
Docimastes ensiferus.

FIG. 8.-1, anther; 2, pollen grain of Hollyhock (Althaea rosea) enlarged. The pollen grain bears numerous spines, the dark spots indicate thin places in the outer wall.

d. Insect-pollinated, Entomophilae, a very

FIG. 9.-Pollination of Salvia pratensis.
I, Flower visited by a humble-
bee, showing the projection of
the curved connective bearing
the anther from the helmet-

4, The staminal apparatus at rest, with connective enclosed within the upper lip.

large class characterized by sticky (From Strasburger's Lehrbuch der Botanik, by permission of Gustav Fischer.)
pollen grains, the surface of which bears
spines, warts or other projections (fig. 8)
which facilitate adhesion to some part
of the insect's body, and a relatively
small stigma with a sticky surface.
The flowers have an attractive floral
envelope, are scented and often contain
honey or a large amount of pollen;
by these means the insect is enticed
to visit it. The form, colour and
scent of the flower vary widely,
according to the class of insect whose

shaped upper lip and the depo-
sition of the pollen on the back
of the humble-bee.

2, Older flower, with connective
drawn back, and elongated style.

3, The same, when disturbed by the entrance of the proboscis of the bee in the direction of the arrow; f, filament; c, connective; s, the obstructing half of the anther.

1 See A. Kerner, Plants and their Unbidden Guests.

In Broom there is an explosive machanism; the pressure of the insect visitor on the keel of the corolla causes a sudden release of the stamens and the scattering of a cloud of pollen over its body. 6. Lepidopterid flowers, visited chiefly by Lepidoptera, which are able to reach the nectar concealed in deep, narrow tubes or spurs by means of their long slender proboscis. Such are: (a) Butterfly-flowers, usually red in colour, as Dianthus carthusianorum; (b) Moth-flowers, white or whitish, as honeysuckle (Lonicera periclymenum).

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FIG. 10. Spadix of Arum maculatum from which the greater part of the spathe has been cut away.

P, Pistillate, s, staminate flowers; h, sterile flowers forming a circlet of stiff hairs closing the mouth of the chamber formed by the lower part of the spathe.

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7. Fly flowers, chiefly visited by
Diptera, and including very
different types:-

a. Nauseous flowers, dull and
yellowish and dark purple in
colour and often spotted, with
a smell attractive to carrion
flies and dung flies, e.g. species
of Saxifraga.

b. Pitfall flowers such as Asarum,
Aristolochia and Arum macu-
latum, when the insect is
caught and detained until
pollination is effected (fig.
IO).

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c. Pinch-trap flowers, as in the
family Asclepiadaceae, where
the proboscis, claw or bristle
of the insect is caught in the
clip to which the pairs of
pollinia are attached. Bees,
wasps and larger insects serve
as pollinating agents

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d. Deceptive flowers such as Parnassia, where the conspicuous coronet of glistening yellow balls suggests a plentiful supply of nectar drops (fig. 11).

1

e. Hoverfly flowers, small flowers which are beautifully coloured with radiating streaks pointing to a sharply-defined centre in which is the nectar, as in Veronica chamaedrys (fig. 12). LITERATURE. Joseph Gottlieb Kōlreuter 1 (d. 1806) was the first to study the pollination of flowers and to draw attention to the necessity of insect visits in many cases; he gave a clear account of cross-pollination by insect aid. He was followed by Christian Konrad Sprengel, whose work Das entdeckte Geheimniss der Natur im Bau und in der Befruchtung der Blumen (Berlin, 1793), contains a description of floral adaptations to insect visits in nearly 500 species of plants. Sprengel came very near to appreciating the meaning of cross-pollination in the life of plants when he states that it seems that Nature is unwilling that any flower should be fertilized by its

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own pollen." In 1799 an Englishman, (From Vines's Text Book ou Thomas Andrew Knight, after experiments

Botany, by permission.)

on the cross-fertilization of cultivated FIG. 12.- Flower of
plants, formulated the conclusion that no
Veronica.
plant fertilizes itself through many genera- k, Calyx.
tions. Sprengel's work, which had been u, u, u, The three lobes
almost forgotten, was taken up again by of the lower lip of
Charles Darwin, who concluded that no the rotate corolla.
organic being can fertilize itself through o, The upper lip.
an unlimited number of generations; but s, s, The two stamens.
a cross with other individuals is occasion- n, The stigma.
ally-perhaps at very long intervals-indis-
pensable. Darwin's works on dimorphic flowers and the fertiliza-
tion of orchids gave powerful support to this statement. The
study of the fertilization, or as it is now generally called " pollina-
tion," of flowers, was continued by Darwin and taken up by other
workers, notably Friedrich Hildebrand, Federico Delpino and the
brothers Fritz and Hermann Müller. Hermann Müller's work on
The Fertilization of Flowers by Insects and their Reciprocal Adapta-
tions (1873), followed by subsequent works on the same lines, brought
together a great number of observations on floral mechanisms and
their relation to insect-visits. Müller also suggested a modification
of the Knight-Darwin law, which had left unexplained the numer-
ous instances of continued successful self-pollination, and restated
it on these terms: "Whenever offspring resulting from crossing
comes into serious conflict with offspring resulting from self-
fertilization, the former is victorious. Only where there is no
such struggle for existence does self-fertilization often prove satis-
factory for many generations." An increasing number of workers
in this field of plant biology in England, on the Continent and in
America has produced a great mass of observations, which have
recently been brought together in Dr Paul Knuth's classic work,
Handbook of Flower Pollination, an English translation of which
has been published (1908) by the Clarendon Press.

POLLIO, GAIUS ASINIUS (76 B.C.-A.D. 5; according to some, 75 B.C.-A.D. 4), Roman orator, poet and historian. In 54 he impeached unsuccessfully C. Porcius Cato, who in his tribunate (56) had acted as the tool of the triumvirs. In the civil war between Caesar and Pompey Pollio sided with Caesar, was present at the battle of Pharsalus (48), and commanded against Sextus Pompeius in Spain, where he was at the time of Caesar's assassination. He subsequently threw in his lot with M. Antonius. In the division of the provinces, Gaul fell to Antony, who entrusted Pollio with the administration of Gallia Transpadana. In superintending the distribution of the Mantuan territory amongst the veterans, he used his influence to save from confiscation the property of the poet Virgil. In 40 he helped to arrange the peace of Brundisium by which Octavian (Augustus) and Antonius were for a time reconciled. In the same year Pollio entered upon his consulship, which had been promised him in 43. It was at this time that Virgil addressed the famous fourth eclogue to him. Next year Pollio conducted a successful campaign against the Parthini, an Illyrian people who adhered to Brutus, and celebrated a triumph on the 25th of October. The eighth eclogue of Virgil was addressed to Pollio while engaged in this campaign. From the spoils of the war he constructed the first public library at Rome, in the Atrium Libertatis, also erected by him (Pliny, Nat. hist. xxxv. 10), which he adorned with statues of the most celebrated 1 Vorläufige Nachricht von einigen das Geschlecht der Pflanzen One of the scales which form the coronet in the flower, enlarged. betreffenden Versuchen und Beobachtungen, 3, 4, 6 (Leipzig, 1761).

EN

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FIG. II.-Grass of Parnassus (Parnassia palustris).

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authors, both Greek and Roman. Thenceforward he withdrew from active life and devoted himself to literature. He seems to have maintained to a certain degree an attitude of independence, if not of opposition, towards Augustus. He died in his villa at Tusculum, regretted and esteemed by all.

Pollio was a distinguished orator; his speeches showed ingenuity and care, but were marred by an affected archaism (Quintilian, Inst. x. 1, 113; Seneca, Ep. 100). He wrote tragedies also, which Virgil (Ecl. viii. 10) declared to be worthy of Sophocles, and a prose history of the civil wars of his time from the first triumvirate (60) down to the death of Cicero (43) or later. This history, in the composition of which Pollio received assistance from the grammarian Ateius Praetextatus, was used as an authority by Plutarch and Appian (Horace, Odes, ii. 1; Tacitus, Annals, iv. 34). As a literary critic Pollio was very severe. He censured Sallust (Suetonius, Gram. 10) and Cicero (Quintilian, Inst. xii. 1, 22) and professed to detect in Livy's style certain provincialisms of his native Padua (Quintilian, i. 5, 56, viii. 1, 3); he attacked the Commentaries of Julius Caesar, accusing their author of carelessness and credulity, if not of deliberate falsification (Suet. Caesar, 56). Pollio was the first Roman author who recited his writings to an audience of his friends, a practice which afterwards became common at Rome. The theory that Pollio was the author of the Bellum africanum, one of the supplements to Caesar's Commentarii, has met with little support. All his writings are lost except a few fragments of his speeches (H. Meyer, Orat. rom. frag., 1842), and three letters addressed to Cicero (Ad. Fam. x. 31-33).

See Plutarch, Caesar, Pompey; Vell. Pat. ii. 36, 63, 73, 76; Florus iv. 12, II; Dio Cassius xlv. 10, xlviii. 15; Appian, Bell. civ.; V. Gardthausen, Augustus und seine Zeit (1891), i.; P. Groebe, in Pauly-Wissowa's Realencyclopädie (1896), ii. pt. 2; Teuffel-Schwaben, Hist. of Roman Literature (Eng. trans.), § 221; M. Schanz, Geschichte der römischen Litteratur, pt. 2, p. 20 (2nd ed., 1899); Cicero, Letters, ed. Tyrrell and Purser, vi. introd. p. 80.

PÖLLNITZ, KARL LUDWIG, FREIHERR VON (1692-1775), German adventurer and writer, was born at Issum on the 25th of February 1692. His father, Wilhelm Ludwig von Pöllnitz (d. 1693), was in the military service of the elector of Brandenburg, and much of his son's youth was passed at the electoral court in Berlin. He was a man of restless and adventurous disposition, unscrupulous even for the age in which he lived, visited many of the European courts, and served as a soldier in Austria, Italy and Spain. Returning to Berlin in 1735 he obtained a position in the household of King Frederick William I. and afterwards in that of Frederick the Great, with whom he appears to have been a great favourite; and he died in Berlin on the 23rd of June 1775.

Pöllnitz's Mémoires (Liége, 1734), which were translated into German (Frankfort, 1735), give interesting glimpses of his life and the people whom he met, but they are very untrustworthy. He also wrote Nouveaux mémoires (Amsterdam, 1737); Etat abrégé de la cour de Saxe sous le règne d'Auguste III. (Frankfort, 1734; Ger. trans., Breslau, 1736); and Mémoires pour servir à l'histoire des quatres derniers souverains de la maison de Brandenbourg, published by F. L. Brunn (Berlin, 1791; Ger. trans., Berlin, 1791). Perhaps his most popular works are La Saxe galante (Amsterdam, 1734), an account of the private life of Augustus the Strong, elector of Saxony and king of Poland; and Histoire secrète de la duchesse d'Hanovre, épouse de Georges I. (London, 1732). There is an English translation of the Mémoires (London, 1738-1739). See P. von Pöllnitz, Stammtafeln der Familie von Pöllnitz (Berlin, 1894); and J. G. Droysen, Geschichte der preussischen Politik, pt. iv. (Leipzig, 1870).

POLLOCK, the name of an English family which has contributed many important members to the legal and other professions. David Pollock, who was the son of a Scotsman and built up a prosperous business in London as a saddler, had three distinguished sons: Sir David Pollock (1780-1847), chief justice of Bombay; Sir Jonathan Frederick Pollock, Bart. (1783-1870), chief baron of the exchequer; and Sir George Pollock, Bart. (1786-1872), field-marshal. Of these the more famous were the two last. Field Marshal Sir George Pollock, who rendered valuable military service in India, and especially in Afghanistan in 1841-1843, ended his days as constable of the Tower of London, and was buried in Westminster Abbey; his baronetcy, created in 1872, descended to his son Frederick (d. 1874), who assumed the name of Montagu-Pollock, and so to his heirs. Chief Baron Sir J. Frederick Pollock, who had been senior wrangler at Cambridge, and became F.R.S. in 1816, was raised to the bench in 1844, and created a baronet in 1866. He was twice married

and had eight sons and ten daughters, his numerous descendants being prominent in many fields. The chief baron's eldest son, Sir William Frederick Pollock, 2nd Bart. (1815-1888), became a master of the Supreme Court (1846) and queen's remembrancer (1874); his eldest son, Sir Frederick Pollock, 3rd Bart. (b. 1845), being the well-known jurist and legal historian, fellow of Trinity College, Cambridge, and Corpus professor of jurisprudence at Oxford (1883-1903), and the second son, Walter Herries Pollock (b. 1850), being a well-known author and editor of the Saturday Review from 1883 to 1894. The chief baron's third son, George Frederick Pollock (b. 1821), became a master of the Supreme remembrancer in 1886; among his sons were Dr W. Rivers Court in 1851, and succeeded his brother as queen's (king's) Pollock (1859-1909), Ernest Murry Pollock, K.C. (b. 1861), and the Rt. Rev. Bertram Pollock (b. 1863), bishop of Norwich, and previously head master of Wellington College from 1893 till 1910. The chief baron's fourth son, Sir Charles Edward Pollock (1823-1897), had a successful career at the bar and in 1873 became a judge, being the last survivor of the old barons of the exchequer; he was thrice married and had issue by each wife.

POLLOK, ROBERT (1798–1827), Scottish poet, son of a small farmer, was born at North Moorhouse, Renfrewshire, on the 19th of October 1798. He was trained as a cabinet-maker and afterwards worked on his father's farm, but, having prepared himself for the university, he took his degree at Glasgow, and studied for the ministry of the United Secession Church. He published Tales of the Covenanters while he was a divinity student, and planned and completed a strongly Calvinistic poem on the spiritual life and destiny of man. This was the Course of Time (1827), which passed through many editions and became a favourite in serious households in Scotland. It was written in blank verse, in ten books, in the poetic diction of the 18th century, but with abundance of enthusiasm, impassioned elevation of feeling and copious force of words and images. The poem at once became popular, but within six months of its publication, on the 18th of September 1827, its author died of consumption. POLLOKSHAWS, a police burgh and burgh of barony of Renfrewshire, Scotland, on the White Cart, now virtually a suburb of Glasgow, with which it is connected by electric tramway and the Glasgow & South-Western and Caledonian railways. Pop. (1901), 11,183. It is named from the shaws or woods (and is locally styled "the Shaws ") and the lands of Pollok, which have been held by the Maxwells since the 13th century. The family is now called Stirling-Maxwell, the estate and baronetcy having devolved in 1865 upon Sir William Stirling of Keir, who then assumed the surname of Maxwell. Pollok House adjoins the town on the west. The staple industries are cotton-spinning and weaving, silk-weaving, dyeing, bleaching, calico-printing and the manufacture of chenille and tapestry, besides paper mills, potteries and large engineering works. Pollokshaws was created a burgh of barony in 1813, and is governed by a council and provost. About 2 m. southwest is the thriving town of Thornliebank (pop. 2452), which owes its existence to the cotton-works established towards the end of the 18th century.

POLL-TAX, a tax levied on the individual, and not on property or on articles of merchandise, so-called from the old English poll, a head. Raised thus per capita, it is sometimes called a capitation tax. The most famous poll-tax in English history is the one levied in 1380, which led to the revolt of the peasants under Wat Tyler in 1381, but the first instance of the kind was in 1377, when a tax of a groat a head was voted by both clergy and laity. In 1379 the tax was again levied, but on a graduated scale. John of Gaunt, duke of Lancaster, paid ten marks, and the scale descended from him to the peasants, who paid one groat each, every person over sixteen years of age being liable. In 1380 the tax was also graduated, but less steeply. For some years after the rising of 1381 money was only raised in this way from aliens, but in 1513 a general poll tax was imposed. This, however, only produced about £50,000, instead of £160,000 as was expected, but a poll-tax levied in 1641 resulted in a revenue of about £400,600. During the reign of

the chief accountant in 1572, went on a special mission to Barcelona in 1580, and died there in 1591. Timoneda, in the Sarao de amor (1561), alludes to him as a poet of repute; but of his miscellaneous verses only two conventional, eulogistic sonnets and a song survive. Polo finds a place in the history of the novel as the author of La Diana enamorada, a continuation of Montemayor's Diana, and perhaps the most successful continuation ever written by another hand. Cervantes, punning on the writer's name, recommended that "the Diana enamorada should be guarded as carefully as though it were by Apollo himself "; the hyperbole is not wholly, nor even mainly, ironical.

Charles II. money was obtained in this way on several occasions, | commission which visited Valencia in 1571, became coadjutor to although in 1676-1677 especially there was a good deal of resentment against the tax. For some years after 1688 polltaxes were a favourite means of raising money for the prosecution of the war with France. Sometimes a single payment was asked for the year; at other times quarterly payments were required. The poll-tax of 1697 included a weekly tax of one penny from all persons not receiving alms. In 1698 a quarterly poll-tax produced £321,397. Nothing was required from the poor, and those who were liable may be divided roughly into three classes. Persons worth less than £300 paid one shilling; those worth £300, including the gentry and the professional classes, paid twenty shillings; while tradesmen and shopkeepers paid ten shillings. Non-jurors were charged double these rates. Like previous poll-taxes, the tax of 1698 did not produce as much as was anticipated, and it was the last of its kind in England.

Many of the states of the United States of America raise money by levying poll-taxes, or, as they are usually called, capitation taxes, the payment of this tax being a necessary preliminary to the exercise of the suffrage.

See S. Dowell, History of Taxation and Taxes in England (1888), vol. iii.; and W. Stubbs, Constitutional History (1896), vol. ii.

POLLUX, JULIUS, of Naucratis in Egypt, Greek grammarian and sophist of the 2nd century A.D. He taught at Athens, where, according to Philostratus (Vit. Soph.), he was appointed to the professorship of rhetoric by the emperor Commodus on account of his melodious voice. Suïdas gives a list of his rhetorical works, none of which has survived. Philostratus recognizes his natural abilities, but speaks of his rhetoric in very moderate terms. Pollux is probably the person attacked by Lucian in the Lexiphanes and Teacher of Rhetoricians. In the Teacher of Rhetoricians Lucian satirizes a worthless and ignorant person who gains a reputation as an orator by sheer effrontery; the Lexiphanes, a satire upon the use of obscure and obsolete words, may conceivably have been directed against Pollux as the author of the Onomasticon. This work, which we still possess, is a Greek dictionary in ten books, each dedicated to Commodus, and arranged not alphabetically but according to subject-matter. Though mainly a dictionary of synonyms and phrases, chiefly intended to furnish the reader with the Attic names for individual things, it supplies much rare and valuable information on many points of classical antiquity. It also contains numerous fragments of writers now lost. The chief authorities used were the lexicological works of Didymus, Tryphon, and Pamphilus; in the second book the extant treatise of Rufus of Ephesus On the Names of the Parts of the Human Body was specially

consulted.

The chief editions of the Onomasticon are those of W. Dindorf (1824), with the notes of previous commentators, I. Bekker (1846), containing the Greek text only, and Bethe (1900). There are monographs on special portions of the vocabulary; by E. Rohde (on the theatrical terms, 1870), and F. von Stojentin (on constitutional antiquities, 1875).

POLLUX, or POLLUCITE, a rare mineral, consisting of hydrous caesium and aluminium silicate, H2Cs,Al(SiO3)9. Caesium oxide (Cs2O) is present to the extent of 30-36 %, the amount varying somewhat owing to partial replacement by other alkalis, chiefly sodium. The mineral crystallizes in the cubic system. It is colourless and transparent, and has a vitreous lustre. There is no distinct cleavage and the fracture is conchoidal. The hardness is 6 and the specific gravity 2.90. It occurs sparingly, together with the mineral castor (see PETALITE), in cavities in the granite of the island of Elba, and with beryl in pegmatite veins at Rumford and Hebron in Maine. POLO, GASPAR GIL (?1530-1591), Spanish novelist and poet, was born at Valencia about 1530. He is often confused with Gil Polo, professor of Greek at Valencia University between 1566 and 1573; but this professor was not named Gaspar. He is also confused with his own son, Gaspar Gil Polo, the author of De origine et progressu juris romani (1615) and other legal treatises, who pleaded before the Cortes as late as 1626. A notary by profession, Polo was attached to the treasury

The book is one of the most agreeable of Spanish pastorals; interesting in incident, written in fluent prose, and embellished with melodious poems, it was constantly reprinted, was imitated by Cervantes in the Canto de Caliope, and was translated into English, French, German and Latin. The English version of Bartholomew Young, published in 1598 but current in manuscript fifteen years earlier, is said to have suggested the Felismena episode in the Two Gentlemen of Verona; the Latin version of Caspar Barth, entitled Erotodidascalus (Hanover, 1625), is a performance of uncommon merit as well as a bibliographical curiosity.

POLO, MARCO (c. 1254-1324), the Venetian, greatest of medieval travellers. Venetian genealogies and traditions of uncertain value trace the Polo family to Sebenico in Dalmatia, and before the end of the 11th century one Domenico Polo is found in the great council of the republic (1094). But the ascertained line of the traveller begins only with his grandfather. Andrea Polo of S. Felice was the father of three sons, Marco, Nicolo and Maffeo, of whom the second was the father of the subject of this article. They were presumably "noble," i.e. belonging to the families who had seats in the great council, and were enrolled in the Libro d' Oro; for we know that Marco the traveller is officially so styled (nobilis vir). The three brothers were engaged in commerce; the elder Marco, resident apparently in Constantinople and in the Crimea (especially at Sudak), suggests, by his celebrated will, a long business partnership with Nicolo and Maffeo.

About 1260, and even perhaps as early as 1250, we find Nicolo and Maffeo at Constantinople. Nicolo was married and had left his wife there. The two brothers went on a speculation to the Crimea, whence a succession of chances and openings carried them to the court of Barka Khan at Sarai, further north up to Bolghar (Kazan), and eventually across the steppes to Bokhara. Here they fell in with certain envoys who had been on a mission from the great Khan Kublai to his brother Hulagu in Persia, and by them were persuaded to make the journey to Cathay in their company. Under the heading CHINA the circumstances are noticed which in the last half of the 13th century and first half of the 14th threw Asia open to Western travellers to a degree unknown before and since-until the 19th century. Thus began the medieval period of intercourse between China and catholic Europe. Kublai, when the Polos reached his court, was either at Cambaluc (Khanbaligh, the Khan's city), i.e. Peking, which he had just rebuilt, or at his summer seat at Shangtu in the country north of the Great Wall. It was the first time that the khan, a man full of energy and intelligence, had fallen in with European gentlemen. He was delighted with the Venetian brothers, listened eagerly to all they had to tell of the Latin world, and decided to send them back as his envoys to the pope, with letters requesting the despatch of a large body of educated men to instruct his people in Christianity and the liberal arts. With Kublai, as with his predecessors, religion was chiefly a political engine. Kublai, the first of his house to rise above the essential barbarism of the Mongols, had perhaps discerned that the Christian Church could afford the aid he desired in taming his countrymen. It was only when Rome had failed to meet his advance that he fell back upon Buddhism as his chief civilizing instrument.

The brothers arrived at Acre in April 1269. They learned that Clement IV. had died the year before, and no new pope had yet been chosen. So they took counsel with an eminent churchman, Tedaldo, archdeacon of Liége and papal legate for the

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