ed by the number of the separate stamens, as monandria, diandria, triandria, &c. 19. Syngenesia (grown together), or compound flowers. Almost all the flowers belonging to this class consist of a number of small flowers united. This class has six orders—(a.) polygamia æqualis, if the compound flower consists of perfect flowers only; (b.) polygamia superflua, when in one compound flower there are fertile female flowers, styliferous as well as perfect flowers; (c.) polygamia frustraned, when there are perfect flowers, and female flowers, but the former only fertile and yielding seed; (d.) polygamia necessaria, in which the reverse takes place, and the hermaphrodite flowers have no real stigmas; (e) polygamia segregata, in which there are two sets of calyces, the outer, or common involucrum, and an inner or included calyx containing one or more florets, and thus producing as it were a doubly compound flower; (f) monogamia (an order now abolished) was so named because it had no compound flowers. 20. Gynandria, of which the character is, that the stamens, one or more, are attached to the pistil or style. The orders are determined by the number of stamens, and are denominated monandria, diandria, &c. 21. Monacia (one-housed plants), in which the sexes are separate, yet on one stem. The orders in this class are not only determined by the number of stamens, but there are also monadelphia, syngenesia and gynandria. In the last un imperfect pistil exists in the male flowers, on which stand the stamens. 22. Diacia (two-housed plants), with entirely separate sexes, i. e. in which one plant produces only male, the other only female flowers. The orders are as in the 21st class. 23. Polygamia (a class now generally abolished and incorporated with diacia); plants with complete and incomplete flowers distributed on two or three different individuals of the same species. The three orders of this class are called monacia, diæcia and triæcia, according to the mixture on one, two or three stems. 24. Cryptogamia. To this class Linnæus refers all plants in which he found no sexual parts; but in many they have been since discovered, and even in those in which they are not yet known, they certainly are not wanting. It contains four orders: -1. ferns; 2. mosses; 3. sea-weeds, liverworts, lichens; and, 4. fungi. The palms, whose sexual parts Linnæus was unable to determine, and which he therefore described in an appendix, are at present distributed among the other classes. Later

botanists have reduced the 24 classes to 20. This sexual system (so called) has been opposed by Schelver (Kritik der Lehre von den Geschlechtern der Pflanzen (Heidelb., 1812), and Fortsetzung der Kritik (Carlsruhe, 1814), and particularly Henschel, Ueber die Sexualität der Pflanzen (Bresl., 1820), whose views have attracted much attention. They start from the principle that the animal has the advantage of the plant in individuality, both in the general structure and in that of the various parts, and that the individuality which is the most prominent, is the animal generation; on the other hand, that with plants the similarity in the general structure, as well as in that of the single parts, is incompatible with diversity of sex, and that therefore all proofs alleged in support of the latter must undergo a reexamination. Henschel undertook this; but Treviranus, in his Die Lehre vom Geschlechte der Pflanzen (Brem., 1822), has contradicted most of his statements. Yet the famous K. Sprengel adheres fully to Henschel's views. To this artificial system is opposed the natural, which is founded on the presence or absence of the chief organs, because plants differ from each other chiefly in this way. Oken followed this system in his Natural History for Schools (Leipsic, 1821). And such an one only can give an insight into the great and beautiful order of this vast kingdom of nature.

See Decandolle's Organographie Végétale (2 vols., 60 engrav.). As a convenient manual, we would refer the reader to Nuttall's Introduction to Systematic and Physiological Botany, 2d edit., Cambridge (Mass.), 1830. Respecting vegetable geography, see Schouw's Diss. de Sedibus Plantarum originariis (1816); his Grundzüge einer Allg. Pflanzengeographie (Copenhagen, 1822; translated from the Danish into German, Berlin, 1823); Atlas of Veget. Geography (Berlin, 1824); Alexander von Humboldt's works; particularly the introduction to Bonpland's (q. v.) work, Nova Genera et Species Plantarum, by Kunth.-Anatomy of Plants. A more accurate knowledge of the organization of plants has been obtained chiefly by the zealous and patient investigations of German and French naturalists, as Sprengel, Link, Treviranus, Mirbel, Richard, and many others. A short view of the organization of plants must suffice for our purpose. I. General Structure of Plants. The primitive form, which appears in the earliest stage even of the lowest plant, is the globule, which we may observe even in the nourishing juice, which exudes from

the inner bark (liber) of trees. These globules, becoming connected, form a texture of cellules, which is universally diffused through the vegetable world. The sides of these cells are entire, without any apertures, so that one cell has no communication with the others; but the juices contained in them perspire organically in the same way as those in the animal body. In those cases in which the globules do not touch each other on all sides, they leave interstices, which serve as passages for the juices, particularly in trees with acicular leaves. Yet these passages are very often wanting in the cellular texture, because the little globules which form the latter are attracted so uniformly, that regular spaces are produced, the sides of which are perfect squares, pentagons or hexagons. The cellular texture serves for the preservation and preparation of the juices. Hence it is generally filled with mucilaginous, saccharine, oily or resinous substances. The cellular texture, in the more perfect plants, has a remarkable connexion with the air. From the ferns upward, it becomes more regular towards the surface of the plant, and full of spaces, which are filled with air, received through apertures of a peculiar organization. These apertures are found mostly where a green surface covers the plant, most frequently, however, on the lower surface of the leaves. They are more or less oval, generally surrounded by a glandulous ring, and have, sometimes, below them, small folds, which keep them open. They may be considered as destined to inhale and to exhale, but merely gases, not watery liquids. The second original formation is the rectilinear, fibrous, or, more properly, tubular structure. Powerful magnifiers show that the fibres are real tubes filled with juice, but not continuous, but here and there terminating in a point, e. g. in the liber of trees, also in the alburnum and in the (so called) nerves and ribs of leaves. Their first beginnings appear already in the mucilaginous nourishing juice, where they have the form of needles, and crystallize as it were in bundles. These tubes have the softest skin and the smallest diameter among all the original formations; yet they are extremely extensible and tough. They form what is spun as flax, and what is obtained for useful purposes from hemp, from the paper-mulberry, &c. Their chief purpose seems to be the conducting of the ascending juices. The third original formation is called the spiral form, because it consists primitively of fibres spirally

wound, which form the sides of cylindrical canals. This formation appears, from the ferns upward, in the more perfect plants, surrounded by the vessels in bundles and single. In the trunk of common trees, it generally forms the alburnum and the wood. With the palms, the grasses, &c., the spiral bundles are distributed in the cellular texture. The spiral canals pass through all parts. Through the leafstalk they penetrate with the vessels that convey the juices into the nerves of the leaves, through the flower stalk into the corollæ, into the filaments, the ovaries, the pistils, even into the seeds. As long as they remain original, they have no wall, but that which is formed by those winding fibres. But they are not always found in this original form. They appear often as annular vessels, often as stair-shaped, or as perforated vessels, &c. At length there are transitions from them to the cellular form, particularly in the trees with acicular leaves. Here appear oblong cells perforated with regular holes provided with margins; nay, in the yew we even find cells with divisions winding spirally, which probably take the place of the spiral canals not existing here. The function of this third original formation seems to be the preparation and conducting of the gases, the moisture, &c., which proceed from the juices of the plants. II. Particular Structure of the single Parts of Plants. The root. The surface even of the firmest roots is surrounded with fine hairs, and the points are covered with a spongy cap, by which and the hairs the absorption of the moisture in the ground is carried on. A bundle of tubes passes through the centre of the root, in which there is no pith. The stem consists in woody dicotyledonous plants of three distinct parts-the bark, the wood and the pith. The bark is composed of four parts, 1. a dry, leathery, tough membrane, the cuticle; 2. a cellular layer adhering to the cuticle, and called the cellular integument; 3. a vascular layer; and, 4. a whitish layer, apparently of a fibrous texture, the inner bark, which is of a more complicated structure than the other layers. The wood is at first soft and vascular, and is then called alburnum; but it afterwards becomes hard, and in some trees is of a density almost approaching that of metal. It is composed of concentric and divergent layers, the former consisting of longitudinal fibres and of vessels of various kinds, the latter of flattened masses of cellular substance, which cross the concentric layers. The individual cells are narrow and horizontal in their

length, and extend in series from the centre to the circumference of the wood, so as to form nearly right angles with the tubes of the concentric layers. Various opinions have been entertained respecting the origin of the wood or alburnum. Mr. Knight has proved that the alburnum is formed from the secretion deposited by the vessels of the liber. Wood, while in the state of alburnum, is endowed with nearly as much irritability as the liber, and performs functions of great importance in the vegetable system; but when it is hardened, these functions cease, and in time it loses its vitality, not unfrequently decaying in the centre of the trunks of trees, which often, however, put out new shoots, as if no such decay existed. To carry on, therefore, the functions of the wood, a new circle is annually formed over the old. The hardness of these zones increases with the age of the tree, those in the centre being most dense. In the centre of the wood is the pith, enclosed by the medullary sheath. The pith or medulla in the succulent state of a stem or twig, is turgid with aqueous fluid, but, before the wood is perfected, it becomes dry and spongy, except near the terminal bud, or where branches are given off, in which places it long retains its moisture. In the majority of woody dicotyledons it is longitudinally entire. The color of the pith in the succulent shoot, or the young plant, is green, which, as the cells empty, changes to white; but to this there are some exceptions. In the greater number of plants no vessels are perceptible in the pith. Little is known as yet with certainty concerning its functions. The majority of leaves are composed of three distinct parts, one firm, and apparently ligneous, constituting the framework or skeleton of the leaf; another, succulent and pulpy, fills up the intermediate spaces; and a third, thin and expanded, encloses the other two, and forms the covering for both surfaces of the leaf. The first of these parts is vascular, the second cellular, and the third a transparent cuticular pellicle. The cellular substance becomes more compact towards the upper surface, and is here generally covered by a sort of varnish. Towards the lower surface it becomes looser, and receives those apertures which permit the entrance of air. In flowers the calyx is generally of the same construction with the leaves; but the corolla consists of the most delicate cellular substance, whose inner surface rises in the most delicate prominences. The spiral canals of a very small diameter pass singly through the lower part of the

leaves of the corollæ, and no trace of apertures is to be discovered. The filaments have a similar construction; but the anthers differ in construction from all the other parts. Entirely cellular, they contain, from the beginning, a number of bodies peculiarly formed, called pollen. The surface of the female stigma is covered with the finest hairs, which, without a visible aperture, receive the fructifying mass in the same organic way as the hairs of the root receive the moisture of the earth. The ovary contains, before the fructification, merely little bladders, filled with the nourishing juice. After the fructification, the future plant shows itself first in a little point which floats in that juice. Nourished by the latter, the little plant either swells and developes its parts, the cotyledones particularly becoming visible; or, if the juice is not entirely used up, it coagulates to a body like albumen, and the plant remains in the case of the (so called) monocotyledones, undeveloped.(For the pressing of plants, see Herbarium.) PLANTAGENET, FAMILY OF. (See Great Britain, History of.)

PLANTAIN (plantago major); an insignificant and common weed, introduced here from the eastern continent, and which so closely accompanies the steps of civilized man as to have received from some of our Indian tribes the name of the white man's foot. The leaves are all radical, oval and petiolate, and from amongst them arise several long cylindrical spikes of greenish inconspicuous flowers.

PLANTAIN TREE. By the English this name is frequently applied to a species of banana (musa paradisiaca) now cultivated in all tropical climates. The stem of this plant is soft, herbaceous, fifteen or twenty feet high, with leaves often more than six feet long, and nearly two broad. The spike of flowers is nearly four feet long, and nodding. The fruit, which succeeds the fertile flowers on the lower part of the spike, is eight or nine inches long, and above an inch in diameter, at first green, but when ripe, of a pale-yellow color, and has a luscious, sweet pulp. It is one of the most useful fruits in the vegetable creation, and, as some of the plants are in bearing most of the year, forms the entire sustenance of many of the inhabitants of tropical climates. When used as bread, it is roasted or boiled when just full grown; and when ripe, it is made into tarts, sliced, and fried with butter, or dried and preserved as a sweetmeat. Three dozen plantains are esteemed sufficient to serve one man for a week, in

stead of bread, and will support him much better.

PLASTER OF PARIS. (See Gypsum.) PLASTIC, in the English language used as an adjective only (from the Greek ar Tikos, from #daσow, I form or shape); but in some other languages a word exists, to which, in English, plastics would correspond (Greek Maori). The term is of much importance in the theory of the arts and in criticism. With the Greeks, Germans, &c., it comprises the whole art of shaping figures from hard or soft masses. Three species are distinguished :-1. the art of shaping forms from soft masses, as clay, wax, gypsum, wheat-flour-the ars plastica proper, according to the original meaning of acow: it precedes sculpture; 2. sculpture, or the art of making statues of harder masses (e. g. marble, alabaster, sandstone)—the ars statuaria; 3. the sculptura of the ancients, comprising works cut in wood and ivory. The materials which the ancient artists used chiefly were, 1. clay. Dibutades of Sicyon invented among the Greeks figures of clay. There are very ancient figures of this kind, of Greek and Egyptian origin. 2. Gypsum, used for stucco-work, and still found in antique buildings. The art of casting in gypsum was not known to the Greeks till late. Lysistratus, brother to Lysippus, who lived in the time of Alexander, invented it. Mengs, among the moderns, has devoted great attention to this art. In Dresden and Madrid are collections of his casts, taken from the finest works of the plastic art in Italy. (See Mengs.) 3. Wax. The same Lysistratus invented the art of casting figures of wax. The Roman images were formed of wax, and numberless figures, parts of bodies, &c., are made of it at present in Catholic countries, as offerings to be presented to saints. 4. Wood. The Greeks made many works of wood, from the earliest times to the most flourishing period of art. Wooden statues were erected to the victors in the Olympic games. 5. Ivory. The use of this material for plastic works is also very old, and the Greeks continued to use it much in the times of their highest perfection. The naked parts of the Olympian Jupiter and Minerva, in the Parthenon, were of ivory. 6. Stone. (a) Marble. Among the ancients, the Pentelican and Parian marbles were the most celebrated. Under Vespasian were discovered the Lunensian quarries, at present called Carrara quarries, the marble of which is whiter than the Greek. The Vatican Apollo is made of it. (b) Alabaster. The Etrurians worked

much in it: the Indian was most esteemed. (c) Basalt. (d) Granite. Only the Egyptians worked in this; their statues and obelisks are generally of granite and sienite. There are two sorts of the granite, a red and a bluish sort. (e) Porphyry, of which there are also two sorts, one red, the other greenish, with golden spots. This, the hardest of all stones, was yet frequently wrought by the ancients into statues,as well as vases. (f) Egyptian lime-stone, soft and white,or dark green. 7. Glass, the invention of which is very old. The ancients made of glass not only many utensils for domestic purposes, but also urns of the dead, and great drinking vessels, ornamented with raised work, or cut. Obsidian must be mentioned here, a kind of mountain-crystal, discovered by a certain Obsidius. (See Pitchstone.) 8. Murrhinum. (See Murrhine Vases.) It is probable that it was a kind of Chinese steatite. 9. Metal. (a) Gold, partly employed for entire statues, partly for the covering of ivory statues. (b) Silver. (c) Bronze. This metal was very much used; the best ore for preparing it was obtained by the Greeks from the islands of Delos and Ægina; at a later period, the Corinthian became the most popular. The most common mixture was 12 parts tin to 100 copper. Metals were at first wrought with the hammer; at a later period they were cast. At first, figures were cast in several pieces, which were united by swallow-tails, so called, shaped thus,; at length, the art of casting whole figures was invented, but it afterwards went out of use; and it was not till the sixteenth century that the Italians began again to cast large bronze figures. The first large statue cast in Italy was that of pope Paul III by Guglielmo della Porta. In 1699, the first great work in bronze was cast in Paris. The first of all the figures cast in bronze is ascribed by the Greeks to Rhocus and Theodoros of Samos. (d) Iron, which was the last used for plastic purposes. Glaucus discovered the art of casting iron; at Delphi were consecrated offerings made by him. Never was the art of casting in iron carried to greater perfection than in our times, particularly at Berlin. (See Sculpture.)Plastic, in its narrowest sense, signifying that which is fit to be represented in forms, or is well represented in forms, is opposed to picturesque in its widest sense, signifying that which is fit to be represented, or is well represented in painting. Intimately connected with the general difference between the spirit of ancient and that of modern art, to which we have already

often alluded, is the circumstance that the Greeks had a much greater disposition to express their ideas in forms than in pictures, so far as the fine arts are made use of for the expression of ideas. They accordingly carried the arts which speak through the form to the highest perfection; i. e. the plastic arts. The religion and prevailing sentiments of the Greek led him to view this life as the most important part of his existence, and the perfection of this life as the chief perfection to which he could aspire; whilst the modern, or Christian, considers every thing with reference to a future life, to which he aspires. The chief aim of the latter, in the fine arts, therefore, is the expression of glowing feeling. He makes the forms and beings which he finds on the earth express his views of a more perfect and purer world for which he longs (and colors and tones are the most ready means of so doing), whilst the Greek embodies all his ideas in forms to which he does not attempt to give an expression superior in kind to the terrestrial, like the Christian, but merely idealizes them, i. e. developes their excellences so as to give them what would be terrestrial perfection. On the whole, we may say the ancients strove much more to represent the beautiful for its own sake, whilst with the moderns it is made subsidiary to the expression of feeling. Hence the necessary consequence that, wherever it was admissible, the Greeks represented naked human beauty, the most perfect in creation; and to such a degree did that gifted and finely organized people develope their sense of beauty and the power of embodying it in forms, that they have ever since remained the models of successive ages. So great and general, indeed, was the sense for plastic beauty with the Greeks, that it influenced most of the other branches of art, as painting, which has with the Greeks a decidedly plastic character; and Schlegel is quite correct when he says that, in order to understand perfectly well the tragedy of the Greeks, it is necessary to be thoroughly acquainted with their plastic art, because the mind of the Greek has, in every thing connected with the beautiful, an eminently plastic turn; and the poet does not develope before our eyes great and peculiar characters by a series of events and actions, nor does he present views which are the consequence of connecting all our present existence with another world; but he conceives the existing world idealized, perfected by its own laws, and, if he composes for representation, this

view closely allies itself to the spirit which pervades the sculpture of his country.Plastic is also used in praise of modern poems or historical writing, if they are so well executed that they represent characters or actions as expressively as a sculptor would do by a fine statue.

PLATA, RIO DE LA (that is, river of silver); a large river of South America, which flows into the Atlantic ocean between latitude 34° 55′ and 36° 21' S. It is formed by the union of the Parana and Uruguay. The former rises in Brazil, and receives the Paraguay coming from the same country, after which it unites with the Uruguay, also coming from Brazil, at about 175 miles from the ocean. At this point, the Plata is thirty miles wide; at its mouth, about 100 miles. The Paraguay rises in latitude 13° 30′ S., and receives the large rivers Pilcomayo and Vermejo from the west. The whole length of the Plata, from the head waters of the Paraguay to the ocean, is about 2300 miles. The basin which it drains extends from lat. 13° to 38° S., and from lon. 51° to 74° W., and is therefore about 1800 miles from north to south, by 1500 from east to west. Excepting the Amazon, it has the largest volume of water of any river in the world. The navigation of the Paraguay is difficult on account of the shoals and falls. The Parana is deeper than the Plata, and is rendered dangerous by its numerous sandbanks. The ports on the Plata are Montevideo and Buenos Ayres. It was first discovered by Solis, who gave it the name of La Plata, but from whom it was often also called the river of Solis. Sebastian Cabot, then in the service of Spain, visited the river a few years afterwards (1526), and penetrated to the Paraguay.

PLATA, UNITED PROVINCES OF THE (Provincias Unidas del Rio de la Plata, or Republica Argentina); a republic of South America, consisting of a part of the former Spanish viceroyalty of the Rio de la Plata, or Buenos Ayres. The republic of Bolivia, the state of Paraguay, and the republic of the Banda Oriental, which were comprised within the limits of the viceroyalty, now form independent states. The United Provinces are bounded on the north by Bolivia; on the east by Paraguay, from which they are separated by the river Paraguay, the Banda Oriental (which the Uruguay separates from them), and the Atlantic ocean; south by Patagonia; and west by Chile and the Pacific ocean. The extreme length, from lat. 20° to 40° 10′ S., is about 1400 miles; the breadth varies from 500 to 800 miles.