Part 43

For geometrical crystallography, dealing exclusively with the external form of crystals, reference may be made to N. Story-Maskelyne, _Crystallography, a Treatise on the Morphology of Crystals_ (Oxford, 1895) and W. J. Lewis, _A Treatise on Crystallography_ (Cambridge, 1899). Theories of crystal structure are discussed by L. Sohncke, _Entwickelung einer Theorie der Krystallstruktur_ (Leipzig, 1879); A. Schoenflies, _Krystallsysteme und Krystallstructur_ (Leipzig, 1891); and H. Hilton, _Mathematical Crystallography and the Theory of Groups of Movements_ (Oxford, 1903).

The physical properties of crystals are treated by T. Liebisch, _Physikalische Krystallographie_ (Leipzig, 1891), and in a more elementary form in his _Grundriss der physikalischen Krystallographie_ (Leipzig, 1896); E. Mallard, _Traite de cristallographie, Cristallographie physique_ (Paris, 1884); C. Soret, _Elements de cristallographie physique_ (Geneva and Paris, 1893).

For an account of the relations between crystalline form and chemical composition, see A. Arzruni, _Physikalische Chemie der Krystalle_ (Braunschweig, 1893); A. Fock, _An Introduction to Chemical Crystallography_, translated by W. J. Pope (Oxford, 1895); P. Groth, _An Introduction to Chemical Crystallography_, translated by H. Marshall (London, 1906); A. E. H. Tutton, _Crystalline Structure and Chemical Constitution_, 1910. Descriptive works giving the crystallographic constants of different substances are C. F. Rammelsberg, _Handbuch der krystallographisch-physikalischen Chemie_ (Leipzig, 1881-1882); P. Groth, _Chemische Krystallographie_ (Leipzig, 1906); and of minerals the treatises of J. D. Dana and C. Hintze. (L. J. S.)

FOOTNOTES:

[1] From the Greek letter [delta], [Delta]; in general, a triangular-shaped object; also an alternative name for a trapezoid.

[2] Named after pyrites, which crystallizes in a typical form of this class.

[3] From [Greek: plagios], placed sideways, referring to the absence of planes and centre of symmetry.

[4] From [Greek: gyros], a ring or spiral, and [Greek: eidos], form.

[5] From [Greek: monos], single, and [Greek: klinein], to incline, since one axis is inclined to the plane of the other two axes, which are at right angles.

CRYSTAL PALACE, THE, a well-known English resort, standing high up in grounds just outside the southern boundary of the county of London, in the neighbourhood of Sydenham. The building, chiefly of iron and glass, is flanked by two towers and is visible from far over the metropolis. It measures 1608 ft. in length by 384 ft. across the transepts, and was opened in its present site in 1854. The materials, however, were mainly those of the hall set up in Hyde Park for the Great Exhibition of 1851. The designer was Sir Joseph Paxton. In the palace there are various permanent exhibitions, while special exhibitions are held from time to time, also concerts, winter pantomimes and other entertainments. In the extensive grounds there is accommodation for all kinds of games: the final tie of the Association Football Cup and other important football matches are played here, and there are also displays of fireworks and other attractions.

CSENGERY, ANTON (1822-1880), Hungarian publicist, and a historical writer of great influence on his time, was born at Nagyvarad on the 2nd of June 1822. He took, at an early date, a very active part in the literary and political movements immediately preceding the Hungarian Revolution of 1848. He and Baron Sigismund Kemeny may be considered as the two founders of high-class Magyar journalism. After 1867 the greatest of modern Hungarian statesmen, Francis Deak, attached Csengery to his personal service, and many of the momentous state documents inspired or suggested by Deak were drawn up by Csengery. In that manner his influence, as represented by the text of many a statute regulating the relations between Austria and Hungary, is one of an abiding character. As a historical writer he excelled chiefly in brilliant and thoughtful essays on the leading political personalities of his time, such as Paul Nagy, Bertalan, Szemere and others. He also commenced a translation of Macaulay's _History_. He died at Budapest on the 13th of July 1880.

CSIKY, GREGOR (1842-1891), Hungarian dramatist, was born on the 8th of December 1842 at Pankota, in the county of Arad. He studied Roman Catholic theology at Pest and Vienna, and was professor in the Priests' College at Temesvar from 1870 to 1878. In the latter year, however, he joined the Evangelical Church, and took up literature. Beginning with novels and works on ecclesiastical history, which met with some recognition, he ultimately devoted himself to writing for the stage. Here his success was immediate. In his _Az ellenallhatatlan_ ("L'Irresistible"), which obtained a prize from the Hungarian Academy, he showed the distinctive features of his talent--directness, freshness, realistic vigour, and highly individual style. In rapid succession he enriched Magyar literature with realistic _genre_-pictures, such as _A Proletarok_ ("Proletariate"), _Buborckok_ ("Bubbles"), _Ket szerelem_ ("Two Loves"), _A szegyenlos_ ("The Bashful"), _Athalia_, &c., in all of which he seized on one or another feature or type of modern life, dramatizing it with unusual intensity, qualified by chaste and well-balanced diction. Of the latter, his classical studies may, no doubt, be taken as the inspiration, and his translation of Sophocles and Plautus will long rank with the most successful of Magyar translations of the ancient classics. Among the best known of his novels are _Arnold_, _Az Atlasz csalad_ ("The Atlas Family"). He died at Budapest on the 19th of November 1891.

CSOKONAI, MIHALY VITEZ (1773-1805), Hungarian poet, was born at Debreczen in 1773. Having been educated in his native town, he was appointed while still very young to the professorship of poetry there; but soon after he was deprived of the post on account of the immorality of his conduct. The remaining twelve years of his short life were passed in almost constant wretchedness, and he died in his native town, and in his mother's house, when only thirty-one years of age. Csokonai was a genial and original poet with something of the lyrical fire of Petofi, and wrote a mock-heroic poem called _Dorottya or the Triumph of the Ladies at the Carnival_, two or three comedies or farces, and a number of love-poems. Most of his works have been published, with a life, by Schedel (1844-1847).

CSOMA DE KOROS, ALEXANDER (c. 1790-1842), or, as the name is written in Hungarian, KOROSI CSOMA SANDOR, Hungarian traveller and philologist, born about 1790 at Koros in Transylvania, belonged to a noble family which had sunk into poverty. He was educated at Nagy-Enyed and at Gottingen; and, in order to carry out the dream of his youth and discover the origin of his countrymen, he divided his attention between medicine and the Oriental languages. In 1820, having received from a friend the promise of an annuity of 100 florins (about L10) to support him during his travels, he set out for the East. He visited Egypt, and made his way to Tibet, where he spent four years in a Buddhist monastery studying the language and the Buddhist literature. To his intense disappointment he soon discovered that he could not thus obtain any assistance in his great object; but, having visited Bengal, his knowledge of Tibetan obtained him employment in the library of the Asiatic Society there, which possessed more than 1000 volumes in that language; and he was afterwards supported by the government while he published a Tibetan-English dictionary and grammar (both of which appeared at Calcutta in 1834). He also contributed several articles on the Tibetan language and literature to the _Journal of the Asiatic Society of Bengal_, and he published an analysis of the _Kah-Gyur_, the most important of the Buddhist sacred books. Meanwhile his fame had reached his native country, and procured him a pension from the government, which, with characteristic devotion to learning, he devoted to the purchase of books for Indian libraries. He spent some time in Calcutta, studying Sanskrit and several other languages; but, early in 1842, he commenced his second attempt to discover the origin of the Hungarians, but he died at Darjiling on the 11th of April 1842. An oration was delivered in his honour before the Hungarian Academy by Eotvos, the novelist.

CTENOPHORA, in zoology, a class of jelly-fish which were briefly described by Professor T. H. Huxley in 1875 (see ACTINOZOA, _Ency. Brit._ 9th ed. vol. i.) as united with what we now term Anthozoa to form the group Actinozoa; but little was known of the intimate structure of those remarkable and beautiful forms till the appearance in 1880 of C. Chun's Monograph of the Ctenophora occurring in the Bay of Naples. They may be defined as Coelentera which exhibit both a radial and bilateral symmetry of organs; with a stomodaeum; with a mesenchyma which is partly gelatinous but partly cellular; with eight meridianal rows of vibratile paddles formed of long fused or matted cilia; lacking nematocysts (except in one genus). An example common on the British coasts is furnished by _Hormiphora_ (_Cydippe_). In outward form this is an egg-shaped ball of clear jelly, having a mouth at the pointed (oral) pole, and a sense-organ at the broader (aboral) pole. It possesses eight meridians (costae) of iridescent paddles in constant vibration, which run from near one pole towards the other; it has also two pendent feathery tentacles of considerable length, which can be retracted into pouches. The mouth leads into an ectodermal stomodaeum ("stomach"), and the latter into an endodermal funnel (infundibulum); these two are compressed in planes at right angles to one another, the sectional long axis of the stomodaeum lying in the so-called sagittal (stomodaeal or gastric) plane, that of the funnel in the transverse (tentacular or funnel) plane. From the funnel, canals are given off in three directions; (a) a pair of paragastric (stomachal, or stomodaeal) canals run orally, parallel to the stomodaeum, and end blindly near the mouth; (b) a pair of perradial canals run in the transverse plane towards the equator of the animal; each of these becomes divided into two short canals at the base of the tentacle sheath which they supply, but has previously given off a pair of short interradial canals, which again bifurcate into two adradial canals; all these branches lie in the equatorial plane of the animal, but the eight adradial canals then open into eight meridianal canals which run orally and aborally under the costae; (c) a pair of aboral vessels which run towards the sense-organ, each of which bifurcates; of the four vessels thus formed, two only open at the sides of the sense-organ, forming the so-called excretory apertures. These three sets of structures, with the funnel from which they rise, make up the endodermal coelenteron, or gastro-vascular system. The generative organs are endodermal by origin, borne at the sides of the meridianal canals as indicated by the signs [male] [female]. There exists a subepithelial plexus with nerve cells and fibres, similar to that of jelly-fishes. The sense-organ of the aboral pole is complex, and lies under a dome of fused cilia shaped like an inverted bell-jar; it consists of an otolith, formed of numerous calcareous spheroids, which is supported on four plates of fused cilia termed balancers, but is otherwise free. The ciliated ectoderm below the organ is markedly thickened, and perhaps functionally represents a nerve-ganglion: from it eight ciliated furrows radiate outwards, two passing under each balancer as through an archway, and diverge each to the head of a meridianal costa. These ciliated furrows stain deeply with osmic acid, and nervous impulses are certainly transmitted along them. Locomotion is effected by strokes of the paddles in an aboral direction, driving the animal mouth forwards through the water: each paddle or comb (Gr. [Greek: kteis]; hence Ctenophora) consists of a plate of fused or matted cilia set transversely to the costa. The myoepithelial cells (formerly termed neuro-muscular cells), characteristic of other Coelentera, are not to be found in this group. On the other hand there are well-marked muscle fibres in definite layers, derived from special mesoblastic cells in the embryo, which are embedded in a jelly; these in their origin and arrangement are quite comparable to the mesoderm of Triploblastica, and, although the muscle-cells of some jelly-fish exhibit a somewhat similar condition, nothing so highly specialized as the mesenchyme of Ctenophora occurs in any other Coelenterate. The nematocysts being nearly absent from their group, their chief function is carried out by adhesive lasso-cells.

The Ctenophora are classified as follows:--

Sub-class i. Tentaculata, Order 1. CYDIPPIDEA, _Hormiphora_. " 2. LOBATA, _Deiopea_. " 3. CESTOIDEA, _Cestus_. " ii. Nuda, " _Beroe_.

The Tentaculata, as the name implies, may be recognized by the presence of tentacles of some sort. The CYDIPPIDEA are generally spherical or ovoid, with two long retrusible pinnate tentacles: the meridianal and paragastric canals end blindly. An example of these has already been briefly described. The LOBATA are of the same general type as the first Order, except for the presence of four circumoral auricles (processes of the subtransverse costae) and of a pair of sagittal outgrowths or lobes, on to which the subsagittal costae are continued. Small accessory tentacles lie in grooves, but there is no tentacular pouch; the meridianal vessels anastomose in the lobes. In the CESTOIDEA the body is compressed in the transverse plane, elongated in the sagittal plane, so as to become riband-like: the subtransverse costae are greatly reduced, the subsagittal costae extend along the aboral edge of the riband. The subsagittal canals lie immediately below their costae aborally, but continuations of the subtransverse canals round down the middle of the riband, and at its end unite, not only with the subsagittal but also with the paragastric canals which run along the oral edge of the riband. The tentacular bases and pouches are present, but there is no main tentacle as in Cydippidea; fine accessory tentacles lie in four grooves along the oral edge. The sub-class Nuda have no tentacles of any kind; they are conical or ovoid, with a capacious stomodaeum like the cavity of a thimble. There is a coelenteric network formed by anastomoses of the meridianal and paragastric canals all over the body.

The embryology of _Callianira_ has been worked out by E. Mechnikov. Segmentation is complete and unequal, producing macromeres and micromeres marked by differences in the size and in yolk-contents. The micromeres give rise to the ectoderm; each of the sixteen macromeres, after budding off a small mesoblast cell, passes on as endoderm. A gastrula is established by a mixed process of embole and epibole. The mesoblast cells travel to the aboral pole of the embryo, and there form a cross-shaped mass, the arms of which lie in the sagittal and transverse planes (perradii).

There can be but little question of the propriety of including Ctenophora among the Coelentera. The undivided coelenteron (gastro-vascular system) which constitutes the sole cavity of the body, the largely radial symmetry, the presence of endodermal generative organs on the coelenteric canals, the subepithelial nerve-plexus, the mesogloea-like matrix of the body--all these features indicate affinity to other Coelentera, but, as has been stated in the article under that title, the relation is by no means close. At what period the Ctenophora branched off from the line of descent, which culminated in the Hydromedusae and Scyphozoa of to-day, is not clear, but it is practically certain that they did so before the point of divergence of these two groups from one another. The peculiar sense-organ, the specialization of the cilia into paddles with the corresponding modifications of the coelenteron, the anatomy and position of the tentacles, and, above all, the character and mode of formation of the mesenchyme, separate them widely from other Coelentera.

The last-named character, however, combined with the discovery of two remarkable organisms, _Coeloplana_ and _Ctenoplana_, has suggested affinity to the flat-worms termed Turbellaria. _Ctenoplana_, the best known of these, has recently been redescribed by A. Willey (_Quart. Journ. Micr. Sci._ xxxix., 1896). It is flattened along the axis which unites sense-organ and mouth, so as to give it a dorsal (aboral) surface, and a ventral (oral) surface on which it frequently creeps. Its costae are very short, and retrusible; its two tentacles are pinnate and are also retrusible. Two crescentic rows of ciliated papillae lie in the transverse plane on each side of the sense-organ. The coelenteron exhibits six lobes, two of which Willey identifies with the stomodaeum of other Ctenophora; the other four give rise to a system of anastomosing canals such as are found in _Beroe_ and Polyclad Turbellaria. An aboral vessel embraces the sense-organ, but has no external opening. _Ctenoplana_ is obviously a Ctenophoran flattened and of a creeping habit. _Coeloplana_ is of similar form and habit, with two Ctenophoran tentacles: it has no costae, but is uniformly ciliated. These two forms at least indicate a possible stepping-stone from Ctenophora to Turbellaria, that is to say, from diploblastic to triploblastic Metazoa. By themselves they would present no very weighty argument for this line of descent from two-layered to three-layered forms, but the coincidences which occur in the development of Ctenophora and Turbellaria,--the methods of segmentation and gastrulation, of the separation of the mesoblast cells, and of mesenchyme formation,--together with the marked similarity of the adult mesenchyme in the two groups, have led many to accept this pedigree. In his Monograph on the Polyclad Turbellaria of the Bay of Naples, A. Lang regards a Turbellarian, so to say, as a Ctenophora, in which the sensory pole has rotated forwards in the sagittal plane through 90 deg. as regards the original oral-aboral axis, a rotation which actually occurs in the development of _Thysanozoon_ (Muller's larva); and he sees, in the eight lappets of the preoral ciliated ring of such a larva, the rudiments of the costal plates. According to his view, a simple early Turbellarian larva, such as that of _Stylochus_, most nearly represents for us to-day that ancestor from which Ctenophora and Turbellaria are alike derived. For details of this brilliant theory, the reader is referred to the original monograph.

LITERATURE.--G. C. Bourne, "The Ctenophora," in Ray Lankester's _Treatise on Zoology_ (1900), where a bibliography is given; G. Curreri, "Osservazioni sui ctenofori," _Boll. Soc. Zool. Ital._ (2), i. pp. 190-193 et ii. pp. 58-76; A. Garbe, "Untersuchungen uber die Entstehung der Geschlechtsorgane bei den Ctenophoren.," _Zeitschr. Wiss. Zool._ lxix. pp. 472-491; K. C. Schneider, _Lehrbuch der vergleich. Histologie_ (1902). (G. H. Fo.)

CTESIAS, of Cnidus in Caria, Greek physician and historian, flourished in the 5th century B.C. In early life he was physician to Artaxerxes Mnemon, whom he accompanied (401) on his expedition against his brother Cyrus the Younger. Ctesias was the author of treatises on rivers, and on the Persian revenues, of an account of India (which is of value as recording the beliefs of the Persians about India), and of a history of Assyria and Persia in 23 books, called _Persica_, written in opposition to Herodotus in the Ionic dialect, and professedly founded on the Persian royal archives. The first six books treated of the history of Assyria and Babylon to the foundation of the Persian empire; the remaining seventeen went down to the year 398. Of the two histories we possess abridgments by Photius, and fragments are preserved in Athenaeus, Plutarch and especially Diodorus Siculus, whose second book is mainly from Ctesias. As to the worth of the _Persica_ there has been much controversy, both in ancient and modern times. Being based upon Persian authorities, it was naturally looked upon with suspicion by the Greeks and censured as untrustworthy.

For an estimate of Ctesias as a historian see G. Rawlinson's _Herodotus_, i. 71-74; also the edition of the fragments of the _Persica_ by J. Giimore (1888, with introduction and notes and list of authorities).