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In case of an eclipse of the sun, those parts of the earth between a, b and c, d respectively would be within the penumbra, and the eclipse is partial.

the moon's umbra or true shadow, the eclipse would be total; where the penumbra or partial shadow falls, the eclipse would be partial. The greatest breadth of the former is 180 m. and of the latter 4,900 ra.

Peons. Mexican and S. American serfs, under Spanish laws for debt.

Peony. Pceonia officinalis. Large perennial herb of the natural family Ranunculacece, native of central Europe, widely cultivated for ornament. There are numerous other species, two indigenous in California.

People's Palace. Institution at Mile End Road, inaugurated by the Queen 1887 and intended for the recreation and amusement of the inhabitants of the East End of London. It comprises technical schools, art galleries, concert halls, gymnasium, etc.

Peoria. City of P. co.. 111., on the Illinois; founded 1779. It is entered by 11 railroads, is regularly laid out and has extensive manufactures. Pop., 1890, 41.034.

Pepe, Guglielmo, 1873-1855. Italian officer in Spain; leader of a revolt in Naples 1820; in exile 1821-48, when he held Venice for the patriots; historian of the events in which he bore part.

Peperino. Variety of tuff found near Rome.

Pepin, Lake. Extension of the Mississippi River between "Wis. and Minn., 1 m. below the junction of the St. Croix River. Length 24 m., width 2-4 m.

Pepin, or Pippin, "the Short," 714-768. Son of Charles Martel and father of Charlemagne; became sole Duke of Franks 74"; first king 752; at war with Bavarians, Saracens, Lombards, Saxons, and the Duke of Aquitania. He gave Ravenna, Pentapolis, and the duchy of Rome to the Holy See, and so laid foundation of temporal power.

Pepin of Heriftal, d.714. Founder of Carlovingian line of Frankish kings; Mayor of the Palace under several Merovingian kings; conquered Burgundy and Neustria 687; father of Charles Martel.

Pepo. Fleshy fruit, with a firm rind, composed of the thickened adnate calyx and ovary, as in the Pumpkin, Cucumber, and Melons.

Pepper. Piper nigrum. Herb of the natural family Piper

acece. native of India, yielding from its berries the well known condiments black and white pepper. Red Pepper is derived from the fruit of a species of Capsicum, natural family Solanacece. Other plants produce a similar substance.

Pepper, William, M.D., LL.D., b. 1843. Prof. Univ. Pa. since 1876, and its provost 1881-94.—His father, William, M.D., 1810-1864, was prof. Univ. Pa. 1860-64.

Pepperbusli. Shrubs of the genus Clethra, natural family Clethracece. natives of N. and S. America, bearing odorous white flowers. The two species of the U. S. are known as White Alder.

Peppercorn Rent. Acknowledgment of tenancy when lands are let virtually free of rent; one peppercorn a year to be paid on demand.

Pepperell, Sir William, 1696-1759. Merchant at Kittery, Me.; Chief-justice of Mass. Common Pleas from 1730; leader of an expedition, the most famous of colonial times, which took

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Black Pepper (Piper nigrum).

Louisburg June 1745; Baronet 1746; acting Gov. of Mass. 175658; Lieut.-gen. 1759.

Pcppcrgrass. Herbs of the genus Lepidium, natural family Cruciferm, of wide geographical distribution; also called Peppervvort.

Pcppcridge. Nyssa sylvatica. Large tree of the natural family Cornacea;, native of swampy ground in the e. U.S., furnishing a valuable timber; called also Tupelo, and Black Gum or Sour Gum.

Peppermint. Mentha piperita. Odorous herb of the Mint family, native of Europe; cultivated and introduced into wet places in America, in Mich, and N. Y. See Mint.

Peppermint, Oil Of. Oil of Mentha piperita. The oil is used;in confectionery and in medicine. Its essential constituent is Menthol (q.v.).

Pepper-Pot. Mixed dish of meat or fish with okra and red peppers, originating in W. Indies. In Pa. tripe with dough balls and red peppers are used.

Pepper-Root. Certain species of the genus Cardamine, herbs of the natural family Crucifera;, natives of N. America; known as Toothwort.

Pepsin. Digestive ferment of the gastric juice. As found in the market it is usually prepared from the stomach of the hog, and is employed to aid weak digestion, acting on nitrogenous food only. It changes albuminoids into peptones. It is used in tablets.

Peptones. Bodies containing carbon, hydrogen, nitrogen, sulphur, and oxygen, produced by the action of pepsin upon albuminoids, and by the action of other similar ferments; easily soluble in water and not as readily coagulated as albumens.

Peptonized Food. Any article of food artificially digested by means of some preparation of the pancreas. Peptonized foods are used to afford nourishment when, from any cause, the power of digestion is impaired; e.g., during the weakness consequent upon a low fever or where there is a chronic disease of the stomach. See Pancreatin.

Pepys, Samuel. 1633-1703. Sec. to the Admiralty 1685-88; Pres. Royal Soc. 1684-86. His famous Diary, 1660-69, was first pub. 1825.

Peqnigny. Town of France, on the Somme, near Amiens; notable for a treaty, signed Aug. 28, 1475, which arranged for a 7 years' truce between Frame and England. The English king engaged to quit France on receipt of 75,000 crowns, and to release Queen Margaret for a ransom of 50,000 more. A separate treaty provided for mutual aid in case of revolt in either kingdom.

Pequots, or Pequods. Tribe of Indians in Conn., which was hostile to the whites and caused several conflicts and massacres; nearly exterminated 1637 by a band led by John Mason, assisted by Uncas and the Mohegans. More than 600 Pequots were killed: others were sold as slaves to the W. Indies.

Pera. Suburb of Constantinople, occupied by foreigners and embassies; ravaged by fire 1870.

Per sen. Palestine e. of the Jordan, or part thereof, between Pella and Machasrus.

PcraU. Malay territory held by Britain from 1874. Area ab. 8,000 sq. m., pop. ab. 200,000.

Pcralta, Gaston De. Marquis De Falces, ab.1520-ab.1580. Viceroy of Mexico 1566-67; noted for justice and humanity; Constable of Navarro 1568.

Peralta, Manuel Maria De, b. 1847. Costa Rican author and diplomatist, well known at Washington 1875-78 and later.

Pernlta-Barnuevo, Pedro, 1663-1743. Peruvian author.

Perameles (bandicoot). See Entomophaoa.

Peramelldw. See Entomophaoa.

Per Capita. By heads; according to the number of individuals. See Per Stirpes.

Percentage. Process and result of reckoning by the hundred. The primary elements are the base and the rate per cent: their product is the percentage. The base being given in units, the rate is expressed decimally.

Perception. Psychologically, process of acquiring knowledge of the external world by means of the senses. The basis of perception is therefore sensation, but something more is needed. The object to be perceived must not only arouse a sensation, but must be discriminated, recognized, localized in space and time, and assimilated into the body of conscious ex

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perience. Perhaps the most important act in the complex process of perception is the movement of attention, which brings the sensation or the object producing it into the focus of consciousness, and allows the operation of the processes necessary to the development of perception.

Percesoccs. Sub-orderof Acanthopterous fishes, including the Mullets (Mugilidte), Smelts (Atherinidce), and Barracudas (Sphyrcenidte). These fishes stand between the Perches and the Pikes. They have the ventral fins abdominal in position,the spinous dorsal well separated from the soft dorsal, branchial arches well developed and scales cycloid. The largest species (Mugil albula) averages 2 lbs. in wt. They come in schools to spawn in June. They feed on the mud of the bottom, having a gizzard-like stomach and an extra long intestine; but the mud is partly culled before it is swallowed; the indigestible pieces are thrown out of the mouth. A special arrangement of the pharyngeal bones acts as a filter in the throat. The head is flat and scaly, the body is of pike-like proportions, but has two dorsal fins, and the ventrals are below the pectorals. The anterior dorsal is spiny.

Perceval, Amand-pierre Caussin De, 1795-1871. French Arabic scholar.

Perceval, John, 1680-1748. Irish baronet 1891, Baron 1715, Viscount 1722. Earl of Egmont 1733; grantee of a charter to colonize Georgia 1732.—His grandson, SPENCER, 1762-1812, became M.P. 1796, Atty.-gen. 1802, Chancellor of the Exchequer 1807, Prime Minister 1809, and was murdered.

Percheron. See Horse.

Perches. Percidce, including a large number of species of Acanthopteri. Some are called Pikes, or Pike-perches. Of these the wall-eyed pike, Stizostedion vitreum, is a prominent example. It may attain a weight of 10 to 30 lbs.; the body is more elongated and less compressed than in the yellow perch.

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1. Sea Bass (Labrax liimis), 2. Striped Bass (Serraniis scriba), 8. Wreck Bass (Poli/prion cemuum).

The principal fishery for this species is Saginaw Bay, Lake Huron. The white perch (Morone) belongs to the Labracidce. The sub-family Etheostominoe includes the Darters, which are considered minute perches. The Sunfishes, q. v., (Lepomis) and Black Bass (Micropterxis) of the Centrarchidce have 3 or more anal spines and rudimentary pseudobranchs, while the Sea Bass (Roccus or Labrax) of the Serranidce have large pseudobranchs. These families are by some authors included in the Perch family, here restricted to perches with 1 or 2 anal spines, and rudimentary pseudobranchs (except Stizostedion).

Perchcrs (birds). See Insessores.

Pcrclllorates. Metallic derivatives of perchloric acid.

Perchloric Acid. HC10(. Colorless, fuming liquid, very unstable and explosive. It produces bad wounds when brought in contact with the flesh. It is made by treating potassium perchlorate, KCIO,, with sulphuric acid.

Perclval, James Gates, 1795-1856. American poet, of considerable repute in the past; geologist of Wis. 1854. Clio, 1822-27.

Percurrent. Midvein of a leaf when it extends to but not beyond the apex.

Percussion. The sudden stopping of a body by impact, from which the term has been applied to shells to be exploded upon striking by means of a percussion fuse: the means employed to discharge the musket by a percussion cap, within which is placed a small charge of fulminate. Explosion in such cases is produced by the conversion of mechanical energy into heat.

Percussion. Process in physical diagnosis, which, by tapping various parts of the bodv\ more particularly the chest and abdomen, gives an indication of the physical condition of the organs beneath by the resultant sound.

Percussion Cap. Small copper cylinder containing fulminating powder, a mixture of 7 parts "mercury fulminate and 2 parts potassium chlorate, placed in the lock of a gun to explode the charge. See Fulminates.

Percussion Table. Apparatus used in ore-dressing, in which the pulp flows in a thin sheet over the surface of an inclined table, and is kept in agitation by a succession of blows given either at the upper end or at the side of the table.

Percy, Henry, d. 1408. Fourth Baron of Alnwick: first Earl of Northumberland 1377.—His son, Henry ("hotspur"), 1364-1403, victor of Chevy Chase, 1888, was killed at Shrewsbury, and celebrated by Shakespeare. Others of this line were prominent in war and intrigue.

Percy, John, 1817-1889. Physician in the Queen's Hospital, Birmingham, 1842-51; Lecturer on Metallurgy to the Roval School of Mines 1851-79; pres. Iron and Steel Institute 1885-87. His works on Fuel, Iron and Steel. Silver and Gold, and the metallurgy of the other metals, pub. 1869-80, are standard works, and have been tr. into French, German, and Spanish.

Percy, Thomas, D.D., 1728-1811. Bp. of Dromore 1782. His Reliques of Ancient Englisli Poetry, 3 vols., 1765, is an important collection of ballads, freely revised and enlarged by his own hand.

Percy Anecdotes. Famous collection, published in London, in monthly parts, 1820-23, by Thomas Byerley, d. 1826, and Joseph C. Robertson, d. 1852, who wrote under the name of Shilto and Ruben Percy.

Perdiccas. Kings of Macedonia ab.700. 454-413, and 365360 B.C.

Perdiccas, d. 321 B.C. General of Alexander, and temporary regent after his death, holding his signet-ring.

Pcreda, Jose Maria De, b. 1833. Spanish novelist and descriptive writer.

Perelixe, Hardouin De Beaumont De. 1605-1671. Bp. of Rhodes 1649, Abp. of Paris 1662; persecutor of Port Royal.

Peregrine Falcon (falco PeregriNUS). Hawk formerly used in falconry. It is a very swift flyer. It is known to have attained a speed of 150 m. an hour. The male, called Tercel, is smaller than the female.

Pereiopod. One of the walking legs of the lobster and of allied Crustacea.

Pereira, Jonathan, M.D., F.R.S., 1804-1853. Practitioner and prof, in London. Materia Medica, 1839-40; Diet, 1843.

Pereira da Silva, Joao Manoel, b. 1817. Brazilian historian.

Pereira de Figueiredo, Antonio,

1725-1797. Portuguese priest of the Ora- Hooded Peregrine on the tory. He tr. the Bible and wrote much block, against the Jesuits.

Pcrckop, Isthmus Of. In Russia, connecting the Crimea with the mainland of European Russia. It is crossed by a ship canal.

Pcre-la-Chalse. Cemetery in e. Paris; named from the Jesuit confessor of Louis XIV., whose garden was converted into this burial place 1804.

Perennial. Vegetable structures which endure indefinitely, year after year.

Pereniiibraiichiata (proteida, Sozobranchia). Tribe of Ichthyoidea (Urodele Amphibians), including forms having

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One end of the leash la attached to the Jesses, the other to a ring driven Into the side or top of the block; and thus toe hawk Is prevented from escaping.

PERENNICHORDATA— PERICLES

1155

external gills throughout life, but no maxillary bones. The teeth are in several rows, and borne by the vomer and palatine bones. Here are included: the Siren, or Mud-eel, of S. C, with eel-like body and no posterior limbs; the Proteus of s. Europe,

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Mud-Puppy (Xecturus maculatut).

living- in subterranean waters, having three toes on the fore feet, two on the hind feet, and only two pairs of gill slits; and the Necturus or Menobranehus (known popularly as the Mudpuppy or Water-lizard), with four-toed feet and four pairs of gill slits, abundant in the Great Lake region and Upper Mississippi system.

Pcrennichordata. See Copelatje.

Perez, Antonio, 1539-1611. See., agent, and scapegoat of Philip II. of Spain. Tried for the murder of Escovedo, emissary of Don John of Austria, he confessed under torture, escaped to Aragon, was there repeatedly delivered by popular risings, and fled to France 1591. Relaciones, 1598.

Perez, Jose Joaquin, b. 1801. Pres. of Chili 1861-71.

Perez, Santiago, b. 1830. Colombian author and Senator, twice Minister to the U. S.

Perez de Hlta, Gines. Spanish author. His Civil Wars of Granada, 1595-1604, a mixture of history and romance, has been drawn on by other writers, from Calderon to Irving.

Perez Gald6s. See Gald6s.

Perfect. Flowers which contain both stamens and pistils.

Perfection, In Ethics. Excellence of human nature considered as a rational end for moral action.

Perfectionism. Doctrine professed by many Methodists, some Roman Catholics, and others, that man may through grace attain a sinless state in this life. It is disowned by most Christians.

Perfectionists. Sect founded 1838 in Vt. by J. H. Noyes; transferred 1847 to Madison co., N.Y., and known as the Oneida Community.

Perfect Square. Quantity whose two equal factors can be exactly expressed.

Perfoliate. Sessile leaves having the stem on which they are borne passing through the lower portion of their blades.

Perforata. Section of Foraminifera, including the orders Textularidea. Chilostomellidea, Lagenidea, GlobioeriMdea, Rotalidea, Nummulinidea (q.v.).

Perforata. Division of the Madrepore corals. See Madre

PORAR1A.

Perforated Cake Powder. Used in heavy guns; hexagonal powder prisms having seven perforations from upper to lower base; made by moistening and reworking ordinary grained powder of sp. gr. 1.5 and subjecting it to a pressure of ab. 65,000 lbs. per sq. in. in hexagonal molds. Each prism weighs ab. 555 grs. and has sp. gr. ab. 1.7. Combustion proceeds from interior perforations on increasing surface, and the amount of gas evolved is better proportioned to perform its work with less initial pressure on the bore than in the case of single grained powder.

Perforate Shell. Gastropod shell with a hollow columella.

Perfumery. Art of preparing essences and perfumes. A good perfume should leave no residue on evaporation. Some of the most exquisite perfumes are obtained from the most offensive substances: the oil of pineapple being produced from sugar and putrid cheese. Most of the perfumes come from the vegetable kingdom; musk, civet, castor, and ambergris being

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Restoratinn of the great Altar Building at Pergamus, by R. Bohn.

art in 2d century B.C. Its library of 200,000 vols, was given to Cleopatra by Antony, and added to that of Alexandria. Its ruins were excavated 1878-86, and many sculptures were taken to Berlin.

Pcrgolesl, Giovanni Battista, 1710-1736. Italian composer of the Neapolitan school, best known by his opera La Serva padrona, 1733. and a Stabat Mater for two women's voices with accompaniment of strings.

Perham, Sidney, b. 1819. M.C. 1863-69; Gov. of Maine 1871-74.

Peri. In Oriental Mythology, a Being, harmless or beneficent, and immortal, but not to be admitted to Paradise; most familiar through Moore's poem.

Perl, Jacopo. ab.1600. Florentine musician, one of the creators of the lyric drama (see Opera). He composed the opera Euridice, performed at the marriage of Henry IV. of France.

Periander, ab.665-585 B.C. Tyrant of Corinth.

Perianth. Floral envelopes of a flower, especially in cases where the calyx and corolla are indistinguishable, or where one of them is wanting; sometimes called Perigone.

Perlastre. That point in the orbit of a binary star where the secondary star approaches nearest to the primary.

Perlblem. Layer of cells at the growing points of plants, which develops the bark; immediately beneath the epidermis.

Peribranchial Space. Space surrounding the branchial sac in Tunicates, etc.

Perlcambium. Layer of thin-walled cells, found in the roots of dicotyledonous and gyrnnospermous plants, immediately within the endodermis; periphlasum.

Pericarditis. Inflammation of the pericardium. Frequently a sequel to inflammatory rheumatism. It is often accompanied by a dropsy of the part, known as hydropericardium.

Pericardium. Serous sac enveloping the heart, enabling its movements to be carried on without undue friction. See Serous MemBrane.

Pericarp. Seed-vessel of flowering plants; ripened ovary-wall.

PcrichaHium. Cluster of modified leaves which surrounds the archegones in the flower of a moss.

Perichondrium. In Embryology, membranous investment of dermis which surrounds the cartilaginous cranium and becomes ossified about it to form the membrane bones.

Pcrlcladiuui. Expanded and sheathing base of a petiole, especially in herbs of the Carrot family.

Pericles, ab.495-42fl B.C. Greatest statesman of Athens. He entered public life 469. and by the ostracism of Thucydides 444 was left without a rival. He employed the ten years preceding the Peloponnesian war in adorning Athens with public buildings. His was the golden age of Greece.

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Pericles.

1156

PERICI-INIim—PERIPTERAL,

Pcricliniuin. Involucre of the compound flower or Anthodium of the Composites; also known as Periphoranthium.

Periderm. Hard cuticular layer developed in the cocnosarc of certain Hydroids.—In Botany, the tissue formed externally from the phellogen of stems. Its diminutive is peridiolum.

Peridiiiiu. Investing membrane of the puff-balls, truffles, and other fungi, consisting of several layers of densely matted byphse; also corky layer of the bark in exogenous stems.

Peridot. See Chrysolite.

Peridotitc. Group of basic igneous rocks containing olivine, but no feldspar.

Pcrlenlcron. Blastoccel cavity after the digestive cavity is established in embryos.

Pericr, Casimir, 1777-1832. French Deputv 1817: Finance Mniater 1828-39; Premier 1831. His policy was that of the Juste Milieu.

Pcriers, Jean Bonaventure Des. See Des Periers, BONAVENTURE.

Perigastric Cavity. Perivisceral cavity; body cavity outside of the alimentary canal.

Perigee. Point of the moon's orbit nearest the earth.

Perisenesis. Theory of heredity, according to which protoplasm is made up of small bodies called plastidules, each of which is an organized system of molecules, each molecule having a peculiar form of vibration; the character of the whole is determined by the forms of these vibrations. The vibrations are complex and run through cycles so as to return periodically to the same phase as a result. The plastidule also undergoes a cyclic change of its powers. Changes in the environment modify the vibration systems, and also determine the resultant effective work of the molecule in adding other molecules, or of the plastidule in splitting into new plastidules, for growth is the one and cell-division results from the other. A modification of the system of vibrations constitutes variation, and must always be impressed from without. Thus Hasckel accounts for the cyclic development of ontogeny and the branched development of phytogeny. As to the branched development of the differentiation of tissues, he supposes a similar modification of the vibration along different lines, as each (•ell divides, due to environment. Development is a purely mechanical process, capable of being represented mathematically and graphically. See Weismann's Theory Of Heredity.

Perigone. See Perianth.

Perltfoniiini. Walls of a sporosac or reproductive bud in Medusoids. When mature there are three layers, a middle, mesotheea, an outer, ectotheca, and an inner, endotheca.

Pcrigueux. City of France, 42 m. s.e. of Angouleme, the ancient Vesunna of C;esar*s time. Here are the remains of a Roman amphitheater. It has an archieological museum rich in inscribed stones. Pop., 1891, 28,000.

Perifiy ilium (PERIOYNE). In Botany, sac which incloses the pistil and achenium in the genus Carex; also perichaetium of Iiryophytes.

Perigy nous. Stamens inserted around the pistil of a flower, either on the calyx or corolla; also, disk of a flower when adnate to the base of the calyx.

Perihelion. Point in a planet's or comet's orbit nearest the sun.

Perimeter. Bounding line of a plane figure.

Perimeter. Instrument used for determining the area of the lield of distinct vision of the eye.

Perineum. In Regional Anatomy, the lowest part of the trunk found between the joining of the thighs to the trunk.

Peri it in in. Third layer of cells existing on the spores of certain Jungermanniacece, often beautifully sculptured.

Period. In simple harmonic motion, interval of time between two successive passages of the vibrating body through a given point of its path in the same direction.

Period. In Mathematics, two or more consecutive digits of a number, considered together.

Periodates. Salts derived from periodic acid, HIO„ or from derivatives of normal periodic acid, I(OH),.

Periodic Acid. HlOy Simplest form, made by treating perchloric acid with iodine; white crystals, containing 2H,0.

Periodical*. Magazines and reviews, usually pub. monthly or quarterly: numerous of late in all civilized lauds, and occupying a middle place between newspapers and ordinary books. The Royal Society's Transactions began 1665, the Journal des Savants also 1665, and the Qentlemun's Mag. 1731.

Periodic Function. One in which the same value recurs at regular intervals in the change of the variable.

Periodic Law, In Chemistry, the properties of the elements are periodic functions of their atomic weights.

Periodic Table. Arrangement of the chemical elements in groups and series, in the order of their atomic weights, showing the relation of the properties of the elements and their atomic weights. Such tables have been arranged by Mendeleeff and by Lothar Meyer.

Period of Sun Spot*. Discovered by Sch wabe of Dessau. It is not absolutely constant, but is approximately 11 years in length. The last maximum epoch was 1895.

Pcriusci. People of the native race in Lacedajmon, whose ancestors occupied before the Dorian conquest; regarded by the Spartans as inferiors, but not generally oppressed.

Periostitis. Inflammation of the periostium. It is most frequently experienced in the membrane investing the roots of the teeth; dental periostitis.

Periostium. Sheath of fibrous tissue enveloping bones, except over the articular surfaces. Externally it affords a surface to which the muscles can be attached; internally it serves to give nourishment to the bone and to regenerate the bony tissue, should it be destroyed.

Pcrlostracuni. Epidermal layer on outside of shells of mollusks.

Peripatetics. Disciples of Aristotle. See Lyceum.

Peripat us. See Onychophora.

Pcripliloeui. See Pericambium.

Peripliorantlilum. See Periclinium.

Pcripliyllida*. Family of Peromedusce, including Jellyfish of complex structure, with twelve tentacles, of which four

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Peripvejea—PERMANENT FORTIFICATION

1157

Perlpylaea. Order of siliceous Radiolaria, with a spherical structure to the central capsule which is uniformly perforated. The nucleus is single in the Monocyttaria, and double in the Polyeyttaria. The sub-order Sphcerida includes Haliomma, with the spherical skeleton partly in the central capsule. The sub-order Discida has the skeleton somewhat flattened; Thalassacolla has no connected skeleton. The Polycyttaria consist of colonies of Radiolarians fused by their extra capsular protoplasm, e.g. Colloxpluera.

Perlsarc'. Chitinous envelope secreted about certain Hydroids.

Pcrisclioecliinidae. See Tessellata.

Perlscoplc. Eye-glasses when in the form of converging or diverging menisci. These were proposed first by Wollastou to replace the ordinary double convex and double concave lenses, because by this means a much wider range of vision is obtained: hence the name periscopic glasses.

PerUome. Integument of echinoderms.

Pcrispcrm. See Albumen.

Perisporangium. Indusium of ferns.

Perigpore. In Algology, cell in which tetraspores are formed.

Perifiaad. In Chemistry, element whose valency is expressed by an uneven number.

Perissodaetyla (odd-toed Ungulates). Hoofed Mammals, having the middle toe or digit most developed and serving as the main support of the body. In all. the toes of the hind feet are odd in number, one or three digits being present (in Coryphodon five). When horns are present, they are never supported by a bony core, and are in the median line of the skull even when there are more than one. The stomach is not divided into compartments. There are never less than 22 dorsolumbar vertebra?. The dentition is usually complete. A space is present between the incisors and premolars; the canines, when present, are developed, especially in the upper jaw of the males, into tusks. The families included are Coryvhodontidce, Rhinocerotidte. Tapiridce, Brontotheridte, Palmotheridm, Macraueheniida', Equtdai.

Peristaltic Motion. Action of the muscular coat of the intestines by which the contained substance is moved on regularly.

Peristerlte. Variety of albite feldspar, showing a peculiar iridescence, similar to the colors on the neck of a pigeon; sometimes used as a gem-stone.

Peristeromorpliae. See Columbine.

Peristoma. 1. Lip of the aperture (mouth) of snail-like shells. 2. Region around the mouth of animals, having a circumoral ring of cilia or of tentacles. It includes the space thus inclosed.

Peristome. Row or rows of hair-like processes, called teeth, surrounding the mouth of the sporange or capsule of certain mosses. These teeth are in number always some multiple of 4.

Peristyle. Inelosure of columns surrounding either a building or a vacant space. It is most commonly employed to denote a circle of columns, but is equally applicable to a rectangular arrangement.

Peritlieeinm. Conceptacle which contains the asci in Aseomycetes, an order of Fungi.

Peritoneum. Serous sac covering the contents of the abdomen and lining the abdominal walls. Because of the diverse contents of the abdomen, it is the most complexly formed of all the serous sacs. Its use is to permit the proper movement of the various organs in the abdomen. See Serous Membrane.

Peritonitis. Inflammation of the peritoneum; of many forms and from many causes. Acute peritonitis begins suddenly with agonizing pain. The sufferer lies on his back with shoulders raised and thighs flexed to relax the abdominal walls. The pulse is small and wiry, the abdomen tense and tympanitic. Physicians are divided as to the treatment: some insist upon free catharsis, others upon the free use of opium, and still others say an incision through the abdominal walls and local treatment is necessary. The probability is that all are correct, and skill is required to determine the proper treatment in the individual case.

Peritrcme. Peristome of a Gastropod shell.

Pcritricha. Infusoria with a circle of cilia around a disk,

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Periwinkle (Vinca minor).

in the edge of which is a mouth leading into a pharynx. The opposite pole of the body is adapted for fixation. Vorticella is a typical example.

Perivisceral Cavity. Part of the body cavity that surrounds or contains the viscera.

Periwinkle. Vinca minor. Low, blue-flowered, trailing shrub of the natural family Apocynacea, blooming in early spring; native of Europe; much cultivated as an ornamental plant.

Periwinkle (littoRINA). Medium-s i ze d globular snail of seashores; it feeds on Alga.

Periwinkle, PenNy w i N K L E, Winkle, Wrinkle (sycotypus). Large sea snail, with hairy epidermis; it sometimes destroys oysters.

Pcrizonium. Wall of the auxospore in Diatoms.

Perizonius, or Voorbroek, Jacob. 1651-1715. Prof. Franeker 1681. Leyden 1693; writer on the classics. Origines Babylonue, 1711.

Perjury. Willful false swearing to evidence material to the issue in a legal action. The definition and punishment vary with the statutes of different jurisdictions.

Perkins, Bishop W., 1841-1894. Judge 11th Dist. Kan. 1873-83; M.C. 1885-91; U. S. Senator 1892-93.

Perkins, Charles Allen, 1832-1892. U. S. Minister to Portugal 1869-70; married to a Spanish princess 1870; proscribed in Spain 1874.

Perkins, Charles Callahan, 1823-1886. American writer on art. Italian Scutytors, 1868-83.

Perkins, Eli (melville D. Landon), b. 1840. American humorist. Eli Perkins (at large), 1875.

Perkins, Elisha, 1741-1799. Inventor 1796 of an alleged method of curing rheumatism by "metallic tractors," which was used in London, and caused much controversy; inventor also of an antiseptic drug for other diseases, which failed to save himself when tried for yellow fever.

Perkins, George Hamilton, U.S.N., b. 1836. Lieut. 1861; distinguished at New Orleans and Mobile; Captain 1882.

Perkins, George Roberts, 1812-1876. American mathematician, author of widely-used text-books.

Perkins, Jacob, 1766-1849. American inventor of improvements in banknote engraving, and later of the bathometer, the pleometer, and the steam-gun. He was in England from 1818.

Perkins, Justin. 1805-1869. American missionary in Persia from 1834; translator of the Bible into Syriac.

Perlitic Structure. Structure seen in some vitreous rocks. See Pearlstone.

Perm. City of e. Russia, on the Kama, at the mouth of the Joga Shika. It has extensive smelting works. Pop., 1890, 39.281.

Permanent Fortification. Defensive works erected during peace for the protection of vital strategical points, such as an important harbor, the capital of the State, or other point essential to the security of the State. They require the application of the highest development of the art of fortification, and are intrusted to the care of trained military engineers. In the U.S. the principal harbors on the Atlantic and Pacific coasts are permanently fortified, while in European States the frontiers and capitals are also necessarily cared tor. The recent developments in artillery have greatly modified the character of these works and made obsolete the masonry structures which in I860 were considered abundantly strong. In that day the 64 lb. solid shot could make but little impression upon the 8 ft. of granite wall, but the ton and a half shot of the 17-in. modern rifle demands great thickness of steel armor, or of earthen and concrete batteries to offer a reasonably secure protection to the modern armaments of defense.

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