POLYPHONY. 222 POLYTECHNIQTJE. the intervals in proper succession, and the next step was the combining of two voices into a real luirmonic structure. Instead of the melody Innng only in one voice, as in the following example from Cuido d'Arezzo (q.v. ), Aliile the second voice intoned an organ-point (q.v.), we have a distinct melody in each voice, as in the following example from the fourteenth century: When ]X)lyphony still further developed and three and four voices were employed, the additional voices were also given separate melodies as far as possible. Still polyphony as we now under- stand it had not really begun, for, though tlie voices were combined in an harmonic whole, they did not all assist in the development of a single idea. Composition had musical but not structural unity. With the rise of the great Flemish .School (see iMusic, Schools OF Composition) and the appearance of Dufay, Okeghem. .Jos(iuin Dcpr^s, Willaert, and their contemporaries, polyphony proper came into ex- istence. Practically every form of composition was based on a canon (q.v.) or a fugue (q.v.), and the technical dexterity, the mathematical complexity of these early compositions has never been excelled. The reaction was inevitable. With the death of Palestrina (q.v.) in 1.504, the decline began. The triumph of monody (q.v.) was swift and widespread, and though it in its turn was supplanted by more complex harmonic forms (see H.^K-MOXY), the era of the polyphonic school has never returned. C'on.sult: Oxford History of Music, "The Polyphonic Period," vol. i. (London. I90I ) ; Hope, jiediwral Music (Lon- don, ISnO) : Humphreys, The Evolution of Church .WhsiV ( London," 1890) . POLYPODItTM (Lat., from Gk. roXvirASioi', sort of fern, fmni ttoXuitous, poli/pous, many-foof- ed; so called from the branching rootstoek). One of the largest and most widely distributed genera of ferns, containing at least 3.50 species, in which the sporangia are borne on the back of the frond. The sori are round, distinct, desti- tute of indusium, and are for the most part arranged in one or two rows on each side of the midrib. In some species the sori are irregularly scattered over the fronds. The species grow on rocks, drj' banks, or old logs, and in the tropics many are epiphytic in habit. The venation varies in the different species, and this character was made the basis of systems of classification in which several genera were recognized. Polypo- dium vulgare (polypody), whose fronds grow from two to twelve inches or more in length, is one of the most common and widespread species of America and Europe. There are a number of varieties of this species in Europe, some of which are extensively grown as ornamentals. The rootslocks of a number of species were for- merly employed in medicine, but are now be- lieved to be nearly inert. See Colored Plate of Ferns. POLYPORTTS. A fungus which attacks old trii-^ and tiiiilnr. .'<ee Amabou; Drv Rot. POLYP'TERUS (Xeo-Lat., from Gk. voXIjk. repiic, many-winged, from (ik. Tro/.uf, polys, much, many + rrrepAv, picron, feather, wing). A genus of ganoid fishes of African rivers. Sec BiciiiR; Rekdkish. POLYPUS (Lat., from Gk. tto'/.v-ovc:, polypous, polypu-- in the nose, polyp, niany-footed). In sur- gery, a term employed to signify any sort of pedunculated tumor attached to a surface to which it was supposed to adhere like a many- footed animal, as its name indicates. The most common seat of polvpi is the mucous membrane; hence we have jiolypi of nose, bladder, rectum, and uterus. The only satisfactory mode of treat- ment consists in tlieir removal, which is effected in various ways, as by the forceps, the fcraseur, or tlio ligature. POLYTECHNIC INSTITUTE (from Gk. Tro.iurtjiof, polytcchno.i, skilled in many arts, from iroP.uf, polys, much, many + rixv!/, irchne, art). A school of .science and liberal arts in Brooklyn. X. Y., established in 1854. It granted its first degrees in arts and sciences in 1871 by special authority of the Regents of the State University, and in 1890 was reorganized and received a broad college charter. It now confers the degrees of bachelor of arts and of science, master of arts and of science, and civil, electrical, and mechanical engineer. During the early years of its history the Polytechnic was known as a successful ])rcparatory school, and it still main- tains a preparatory department, as a separate in- stitution, which in 190.3 had 525 students, while the institute had an attendance of 110, with 50 instructors in all departments. The library con- tained 12.000 volumes. POLYTECHNIC SCHOOLS. See TEcnxiCAl El)l CATION. POLYTECHNIQUE (/jcole Polytechniiiue). One of the mn-t famous military preparatory institutions of Europe. It was established by the Xational Convention as the Ecole Coitrale des Travaux Publics in 1794, and in 1795 its name was changed to Ecole Polytechniquc, Although originally intended as a preparatory school for all branches of the public senice, it wfts par- ticularly devoted to the training of civil and military engineers. Vnder the famous matbeinati- cians Lagrange and ilonge. the institution devel- oped rapidly, especially in mathematics and physi- cal sciences, a view being had to their application to technical training. In 1804 X^^apoleon reorgan- ized it on military lines, and under his regime it became a training school for artillerists and en- gineers. Tile Ecole Polytechniquc is under the supervision of the llinister of War. and is de- voted mainly to the preparation of students for the several branches of military and civil engineering. Students must hold the bache- lor's degree in order to become eligible for the competitive entrance examination. The course of studv covers two years, at the end of which period the names of those wlio successfully pass the final examination are placed on a list
