SPOLETO SPONGE 281 Tessonda, and Der Alcliymist, his oratorios Die letzten Dinge and Des Heilands letzte Stunden (known in the respective English versions as " The Last Judgment " and " The Crucifixion "), his symphony Die WeiJie der Tone or "The Consecration of Tone," and other works. In 1852-'3 he directed the performances of his operas at the royal Italian opera house in Lon- don. In 1857 he resigned his office at Cassel. He exercised a decided influence upon the art of music both by his Violinschule (fol., Vienna, 1831) and by his compositions. Among these were nine spmphonies, eight operas, a great number of quartets and quintets for stringed in- struments, and other chamber music. SeeLouis Spohr's SelbsfbiograpMe (2 vols., Gottingen, 1862), which has been translated into English. SPOLETO (anc. Spoletium), a city of central Italy, formerly capital of a papal delegation of the same name, and since 1860 of a district in the province of Perugia (division of Umbria), on the Mareggia, 60 m. N. N. E. of Eome ; pop. in 1872, 20,748. The streets are steep, the city being built around a hill; on the top of this is the citadel, which was built by Theodoric, destroyed by Totila, restored by Narses, and subsequently enlarged. Spoleto has a fine ca- thedral and many other churches, palaces, and relics of antiquity, including the arch known as the gate of Hannibal, who was repulsed here in 217 B. C. The chief articles of trade are maize, wine, fruit, and silk. The ancient Spoletium was a flourishing Roman colony. After the fall of the western empire it was taken by the Goths. Under the Lombard kings it became the capital of a duchy, which soon acquired independence and authority over a considerable part of central Italy, and after various changes was in the 13th century an- nexed to the Roman see. The town was sacked by Frederick Barbarossa, and in 1324 devas- tated by the Perugians; and it has suffered much from earthquakes. SPONGE, the common name applied to the order spongida, of the class of rhizopods, the most characteristic of the subkingdom pro- tozoa. Sponges were for a long time regard- ed as plants, but the best naturalists are now agreed that they belong to the animal king- dom. Prof. H. J. Clark placed them nearest to the compound protozoans known as the flagellate infusoria, and it has been proved by him, and by others since, that the collar round the cilium must be regarded as the sponge animal ; Kent classes them between the flagel- late infusoria and the rhizopods ; and Haeckel stands alone in placing them nearest to the corals or ccelenterata. (See "Annual and Mag- azine of Natural History," London, January, 1870.) A sponge is really an aggregation of separate masses of an amoeba-like sarcode, se- creting a supporting network of fibro-corne- ous, calcareous, or silicious matter, the com- pound mass being traversed by canals opening on the surface. The apparently homogeneous jelly, or sponge flesh, which covers the out- side and lines the canals of the living sponge, is made up of an enormous number of sarcode masses, composed of separate sarcoids, each capable of pushing out its pseudopodia, gener- ally with a vibrating cilium, and, if detached, able to move and live independently. Large rounded orifices, or oscula, are scattered over the surface of most sponges, which lead into sinuous canals permeating the substance in every direction ; water is continually absorbed by the smaller pores of the sponge, filling every part, and, having supplied air and food, is Diagrammatic Section of Spongilla (after Huxley), a a. Outer or superficial layer of sponge. & b. Inhalant apertures, or pores, c c. Ciliated chambers, d. An ex- halant aperture, or osculum. The arrows indicate the direction of the currents. driven out through the oscula; the currents are kept up by the action of the minute vibra- tile cilia. In the words of Prof. Huxley, the sponge " represents a kind of subaqueous city, where the people are arranged about the streets and roads in such a manner that each can easily appropriate his food from the water as it passes along." Many sponges contain a large amount of silica, in the form of spicules of va- rious shapes, both formed in their substance and introduced from without ; two of the most beautiful of the silicious sponges will be found described under GLASS SPONGE and VENUS'S FLOWER BASKET. There is a gradual passage from the soft sponges of commerce to those of stiff and compact texture, with the fibres loaded with silicious spicula, crumbling easily when dry, and useless in the arts ; others are rather of a felted character, usually grayish white. Sponges vary much in form, being irregularly branched, round, pear-shaped, or cup-like, and are fixed by a kind of root at the base, or in- crust other bodies, growing mostly in groups attached to all kinds of objects, living or dead, fixed or floating; most are marine, but spon- gilla (Lam.) grows in fresh water ; they often have brilliant colors. Some, like cliona, in- stead of incrusting other objects, excavate branching cavities in shells, which they in- habit. Sponges are propagated sometimes by ciliated gemmules, yellowish and oval, arising from the sarcode mass and carried out by the currents ; they are mostly formed in the spring, and, after swimming freely about for some time, become fixed and grow. They also produce internal, unciliated, oviform bodies, resembling winter ova, which, when thrown out, swell, burst, and give issue to the locomo-
