Page:The New International Encyclopædia 1st ed. v. 18.djvu/885

* SYLVESTER. 771 SYMBIOSIS. the American Journal of Mathematics and was for some years its editor. Sylvester's contributions were almost exclu- sively in the form of memoirs, scattered through various scientific journals and the proceedings of various societies. They are devoted chiefly to the theories of algebraic forms (see Forms), in which he was the recognized leader of the mathe- matical world. He and Cayley (q.v.) con- tributed more than any of their contemporaries to the theory of invariants, and he may be said to have practically created the vocabulary of the subject. He also puhli.shed a work on iMirs of Verse (1870), a subject in which he always showed an interest. Consult obituary notices in various scientific journals in 1897: aiid Franlilin, Address Comnicmorntice of f^i/lrcslcr (Baltimore. 18P7). SYLVESTER, ,Tosiir. (1.5G3-1G18). An English poet, born in the north of Kent. His life was divided between poetry and trade. He is mainly known for a translation, or rather para- phra.se. of the Scmaincs (Weeks), a sacred epic written by the French poet Du Bartas (q.v.). The translation had considerable infiuence upon ilil- ton. Of Sylvester's original verse, all is forgotten except the beautiful sonnet beginning "Were I as base as is the lowly plaine" (in Palgrave's Golden Treasury). Consult his Works, ed. A. B. Gros- art, "Chertsey Worthies Library" (2 vols., Lon- don, 1878). SYLVESTER DAGGERWOOD. A one-act play by George Colman the younger, jiroduced in 1795, a shorter form of Xew Hatj tit the Old Mar- ket, brought out in the same year. There were only two characters in it, the strolling plaj'er whose name is the title, and Fustian, a play- wright. SYLVICULTURE. See Forestry. SYL'VIUS. The Latinized name of Jacques Dubois (1478-1.5.5.5), a French anatomist, born near Amiens. He studied in Paris, and after- wards was a lecturer on anatomy there. His anatomical discoveries and his invention of in- jection for use in dissection cause him to be re- membered. The Sylvian fissure, the Sylvian aqueduct, and the Sylvian artery were named in his honor. His Opera Medica were published at Geneva in 1(530. SYMBIOSIS (Xeo-Lat., from Gk. avfifiiucic, life together, from civ, si/u. together -|- /3/of, bios, life.) That condition in which two or more dis- similar (U'ganisms live together in an intimate life relation. Various types of symbiosis depend iipon the type of relation existing between the organisms, the so-called symbionts. ( 1 ) JIutualistic symbiosis, or mutualism, is that condition in which each party to the sym- biosis seems to derive advantage therefrom. This relation has perhaps not been proved to exist in plants, though it seems likely that mutualism exists between the legumes and the bacteria of their root tubercles. Many be- lieve that lichens show true mutualism, the fungus symbiont supplying nitrngcuous sub- stances or other materials absorbed from the substratum, and the alga symbiont the carbohy- drates. (2) Antagonistic symbiosis, or parasitism, is that condition where one .symbiont gains at. the expense of the other. There are many illustra- tions of this in nature. F(u- example, the para- sitic fungi and seed plants may be regarded as securing food from their host plants, but not giv- ing an ecpiivalent in return, as is the case in perfect mutualism. (3) A somewhat intermediate condition is illustrated by contingent .symbiosis, or hclolism (q.v.). Some writers hold that lic'hens illus- trate this type, the idea being that there is not a mutual exchange IicIwci'M the alga and the fungus symbiont. The fungus is supposed to gain, but the alga is supposed neither to lose nor gain. Symbiosis may be more or less intimate. In conjunctive symbiosis the symbionts are blended together so as to form a single body, as best illustrated by the lichens. In disjunctive sym- biosis the symbiosis is more temporary, or the symbionts are less completely blended, as illus- trated by ectotropie mycorrhizas. Kelations which are, perhaps, not to be re- garded as s^mdiiosis. but which nevertheless bear a close similarity to it. are frequenth' found. Saprophytism differs from parasitism only in that the host plant, so to speak, is dead. Re- cently a new life relation has been recognized, such as is found in the Indian pipe (Jlonotropa) ; in which case there is a root fungus which de- rives its food materials saprophytically from the soil. Jlonotropa, not being a green plant, gets nearly all of its food material from the fungus. Hence the relation of the two organisms taken together is saprophytism. The nuitual rela- tion of the pair is. however, symbiosis, and the whole relation may be called symbiotic sapro- phytism. This term may be applied to all of the mycorrhiza plants. By some authors lianas and epiphytes have been regarded as having symbiotic relations with the supporting plants, but the relation is not at all intimate, since they prob- ably get only mechanical support. Kerner held a still broader view of symbiosis, applying this term, for instance, to the herbaceous shade plants of the woods, which are unable to grow unless shaded by the trees. Among animals forms of symbiosis are to be found. An example of social symbiosis is the case of a polyp ( Kpizoanthus) or a sea-anemone (Adamsia), which grows on the shell inhabited by a hermit-crab. Klebs states that w-hen the crab changes its shell it seizes the anemone and carries it off to its new home. The term ptii/sioloriiciil siinihiosis may be ap- plied to cases among the lowest organisms where certain alg;e (Zoiixanthellv) often live in Rad- iolaria (q.v.), while similar green and yellow plants inhabit the stomach ei)ithelium of many actinians, corals, and worms. As Hertwig says, the Zouxanthelbp are nourished by the carbon dioxide which is formed by the animal tissues, and breathe out oxygen, which in turn serves as food for the animal. They also form starch and other carbohydrates, and there is nothing to pre- vent any surplus thus formed from becoming food for the animal. A remarkable case of sym- biosis, involving a structural modification, is that of a carpenter bee (of the Oriental genus Koptorthosoma) and a certain mite. A special chamber, with a small orifice for entry, exists in the abdomen of the bee, in which the .cari are lodged. Here it is a little difficult to draw the