Page:Collier's New Encyclopedia v. 09.djvu/250

SYLVANITE 206 SYMBIOSIS ring in distinct crystals, but in an ag- gregation resembling writing charac- ters; hardness, 1.5-2; sp. gr. 7.9-8.33; luster, metallic; color and streak, steel- gray, sometimes brass-yellow. Compo- sition: Tellurium, 55.8; gold 28.5; silver, 15.7 — 100, which corresponds to the for- mula (AgAu)3Te, Occurs usually asso- ciated with gold. SYLVANUS, in mythology, a rural Latin deity, who is generally repre- sented as half a man and half a goat. He was sometimes represented as hold- ing a cypress in his hand. SYLVESTER I., a Pope who governed the Church during the reign of Con- stantine I. He was famous for the num- ber of churches completed during his reign, among them the basilicas St. Peter's and St. Paul's, for his various Church laws and his influence over the emperor. He held office in 314-335. SYLVESTER II., a Pope, a native of Auvergne, was of an obscure family, but received a superior education, study- ing first in the monastery of Aurillac and afterward in Spain. He was made abbot of Bobbio by the Emperor Otho II., and became very distinguished as a teacher. His attainments in science pro- cured him the reputation of a magician. Among the numerous useful inventions attributed to Sylvester II. is the balance clock, which was in use till the adoption of the pendulum in 1650. Sylvester II. was tutor to Otho III., and subsequently head of the school of Rheims, which he made one of the first in Europe, Rob- ert, afterward King of France, was among his pupils. He was called to the papal chair on the death of Gregory V., and administered the affairs of the church with much prudence and modera- tion. He was the first French pope. He died at a great age in 1003. SYLVESTER III., for three months the anti-Pope of Benedict IX. and Greg- ory VI., but deposed by the Synod of Sutri in 1046. SYLVESTER, JAMES JOSEPH, an English mathematician; born in London Sept. 3, 1814, studied at St. John's Col- lege, Cambridge, and was successively professor in University College, Lon- don, in the University of Virginia, in the Johns Hopkins University, Baltimore, and at Oxford (Savilian professor, 1883). He published many memoirs in the scientific journals, and received many medals and honors. He died March 15, 1897. SYLVESTER, JOSHUA, an English author; born in England in 1563. His life was divided between merchandise and poetry, but in neither did he achieve success. Of his original works we have no trace, except the title of the poem published about 1620, entitled "Tobacco Battered and the Pipes Shattered by a Volley of Holy Shot Thundered from Mount Helicon"; but in virtue of the great though short-lived popularity ob- tained by his English version of the "Di- vine Weeks and Works" of Du Bartas he lives in literary history a kind of shad- owy life. It was especially popular with the Puritans and was one of the sources of inspiration for Milton's "Paradise Lost." He led a somewhat wandering existence and died in Middleburg, Hol- land, Sept. 28, 1618. SYMBIOSIS, a biological term intro- duced by De Bary to denote certain kinds of physiological partnership between or- ganisms of different kinds. Consortism is synonymous. As there are many kinds of organic association, it is convenient to restrict the term symbiosis to such intimate and complementary partner- ships as exist between algoid and fungoid elements in lichens, or between unicellu- lar algae and radiolarians. In organic nature there is no isolation; no organism lives or dies to itself; there are countless vital associations, some very indirect and external — e. g., the mutual dependence of some flowers and insects — others very direct and intimate, as in the symbiosis of algae and radiolarians. It often hap- pens that two organisms live together without there being any apparent vital bonds between them; thus diatoms may be "epiphytic" on algje; algas, lichens, mosses, ferns, orchids, etc., are often epiphytic on trees; many algas are "epi- zoic" on animals — e. g., those which live among the hairs of sloths; and one ani- mal may be epizoic on another, as sponges often are on zoophytes. Again, there may be external partnerships, such as those between pilot fish and shark, or between beef-eater birds and wild cattle. These suggest cases of mutualism or commensalism, such as the partnership between certain hermit erabs and sea an- emones. Probably the constant occur- rence of colonies of the algae anabsna in the leaves of the aquatic plant azolla is a similar partnership. Alike in symbi- osis and in commensalism the partner- ships are advantageous to both of the associated organisms, and are therefore to be distinguished from parasitism, in which the benefit is all on one side. It is useful to distinguish these different grades of association, but it cannot be pretended that the distinctions are rigid.