Page:EB1911 - Volume 23.djvu/799

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ROTHWELL—ROTIFERA

operations on a large scale, but on the contrary made it a principle to despise or neglect no feasible opportunity of transacting business, while at the same time his operations gradually extended to every quarter of the globe. He died on the 28th of July 1836, and was succeeded in the management of the London house by his son Lionel (1808-1879), born on the 22nd of November 1808, whose name is associated with the removal of the civil disabilities of the Jews. He was elected a member for the City of London in 1847, and again in 1849 and 1852, but it was not till 1858 that the joint operation of an act of parliament and a resolution of the House of Commons, allowing the omission from the oath of the words to which as a Jew he conscientiously objected, rendered it possible for him to take his seat. He continued to represent the City of London till 1874. His eldest son, Nathan (b. 1840), was created a peer as Baron Rothschild in 1885. Jacob (1792-1868), the youngest of the original brothers, was entrusted with the mission of starting the business in Paris after the restoration of the Bourbons, for whom he negotiated large loans. At the Revolution of 1848 he was a heavy loser, and had also to be protected for a time by a special guard. It was by his capital that the earliest railways were constructed in France; the profits he obtained from the speculation were very large. He died on the 15th of November 1868. The Naples branch was superintended by another of the brothers, Karl (1780-1855). It was always the least important of the five, and after the annexation of Naples to Italy in 1860 it was discontinued.

See Das Haus Rothschild (1858); Picciotto, Sketches of Anglo-Jewish History (1875); Francis, Chronicles and Characters of the Stock Exchange (1853); Treskow, Biographische Notizen über Nathan Meyer Rothschild nebst seinem Testament (1837); Roqueplan, Le Baron James de Rothschild (1868).

ROTHWELL, an urban district in the Normanton parliamentary division of the West Riding of Yorkshire, England, 4 m. S.E. of Leeds. Pop. (1901) 11,702. The church of the Holy Trinity, though largely restored, retains some good Decorated details. Rothwell soon after the Conquest was granted as a dependency of the castle of Pontefract to the Lacys, who erected here a baronial residence of which there are slight remains. Coal and stone are obtained in the neighbourhood, and the town possesses match-works and rope and twine factories in which the majority of the large industrial population is employed.

ROTIFERA (or Rotatoria), a small, in many respects well-defined and somewhat isolated, class of the animal kingdom. Now familiarly known as “wheel animalcules,” from the wheel-like motion produced by the rings of cilia which generally occur in the head region, the so-called rotatory organs, they were first discovered by A. Leeuwenhoek, to whom we also owe the discovery of Bacteria and ciliate Infusoria. Leeuwenhoek described Rotifer vulgaris in 1702, and he subsequently described Melicerta ringens and other species. A great variety of forms were described by other observers, but they were not separated as a class from the unicellular organisms (Protozoa) with which they usually occur, until the appearance of C. G. Ehrenberg's monograph, which contained a mass of detail regarding their structure. At the present day few groups of the animal kingdom are so well known to the microscopist, few groups present more interesting affinities to the morphologist, and few multicellular animals such a low physiological condition.

A rotifer may be regarded as typically a hemisphere or half an oblate spheroid or paraboloid with a mouth somewhere on the flat end (“disk” or “corona”), which bears a usually double ciliated ring, the outer zone the “cingulum,” and inner the “trochus”: this ring serves both for progression and for bringing up food. The body-wall, cuticulized outside, is formed by a single layer of ill defined cells, and surrounds the simple body cavity (archicoele), traversed by simple or branched muscular fibres (“mesenchyme”) (fig. 1, m, m). The mouth opens through a narrow pharynx (p) into a chamber which is (as in Crustacea) at once crop and gizzard, the mastax (ma), whose thickenings are imbedded in the posteroventral wall. A slender ciliated gullet (e) leads into a large stomach (st) whose wall consists of large richly ciliated cells with usually a pair of simple secretory sacs opening into it: it may open through an intestine or rectum into the cloaca. A pair of coiled nephridial tubes (n) formed of a file of perforated “drain-pipe” cells, with ciliated tag-like “flame” cells (f), open into a contractile bladder (bl), which passes by a slender duct into the cloaca. Into this also opens the genital duct from the single or paired gonad (ov). The simple nerve-ganglion or brain (g) lies on the anterodorsal side of the pharynx, and by its position determines the orientation of the animal, the cloacal opening lying on the same side, and the course of the gut being “neural.” The sense organs are a pair of pigmented eyes (oc), and two pairs of antennae, one anterior proximal and near the wreath, the other distal and usually more or less lateral. The sexes are always separate, the males being of very rare occurrence in most cases. In the female the gonad is complex as in flatworms, composed of a germary for the formation of the eggs, and a vitellary, much more conspicuous and alone figured (ov), consisting of a definite number of large nucleated cells for the nourishment of the eggs. The apical end of the rotifer usually narrows suddenly beyond the curve of the gut and the cloacal aperture to form the foot of pseudo podium which ends in an organ of attachment, a pair of movable toes, each with the opening of a cement-gland (gl) at its tip. Thus for orientation we place the rotifer like the cuttle-fish, head downwards: the ciliated disk is basal or oral, proximal to the rest of the animal, the foot is apical, and the brain and cloacal aperture are anterodorsal. It is in this position that free-swimming forms glide over the substratum of organic debris in which they find their food.

The cuticle may be locally or generally hardened, in the latter case being termed a lorica. Often the head is retractile, and a constriction of flexible cuticle distal to it is termed a neck: in Philodinaceae there are a series of thin flexible rings which permit both distal and proximal ends to be telescoped into the middle; and in Taphrocampa, regular constrictions of the whole bodywall give an appearance of metemeric segmentation to the body. In Philodinacea accessory toes are found, unfurnished with cement-glands and distinguished as spurs.

EB1911 Rotifera - Notommata naias.jpg

Fig. 1.—Notommata naias. A and B represent the same animal, some of the organs being shown in one figure and some in the other. oc, eye-spots; g, nerve ganglion; p, pharynx; ma, mastax; e, oesophagus; st, stomach; a, anus, opening into the cloaca; gl, cement-glands in the foot; n, nephridia; f, flame-cells; bl, bladder; m, m, muscles; ov, ovary (vitellarium alone seen).

Corona or Disk.—This typically consists of two concentric zones, the trochus and cingulum, often separated by a groove or gutter which may be finely ciliated; but in several genera of no close affinity, where it is very oblique to the longitudinal axis of the body, it is represented by a general ciliation of the surface (Taphrocampa, Rattulus, Copeus, Adineta). We may suppose that primitively the mouth was seated in the centre of a funnel-shaped disk, surrounded by a double wreath. The nearest approach to this is found in Microcodon (fig. 2, 1) and its allies, the trochus being oval with two median gaps, the cingulum, more delicate, and complete. In Flosculariaceae the trochus is a horseshoe-shaped ridge