Page:The New International Encyclopædia 1st ed. v. 14.djvu/403

NEMATHELMINTHES. 353 NEMERTINEA. of touch exists, ami a IVw ul the fit'c-liviiig spe- cies have two simple eye-spots. The digestive organs are extremely simple. No blood .system nor distinct respiratory or excretory organs can be detected. These worms are unisexual ; but the males are comparatively rarely found, and are always smaller than the females. With the ex- ception of the two families — the Enoplida which are mostly marine forms, and the AnguillulidiE, or paste and vinegar eels — all the animals of this class are parasitic. This phylum is divisible into three very distinct classes, namel}-, Acantlwvcphala, which have a protrusihle proboscis armed with continuous hooks, and are destitute of an intestinal canal; the (Jordiacea, which possess an intestinal canal, but no anus; and the ematoda, which usually possess a perfect intestinal canal, provided with two orifices. See Ascaris; Entozoa; Filauia; Guinea-worm; Pinwoem; Roundworm; Thread- ■voR.MS: Truhixa. NEMATOCYST ( from Gk. >^^o, netna, thread -|- kvitti^^ Ici/stis, bladder). One of the ]assocells. tliread-cells, or nettling organs (cni'fte) of jcllylishes and other Coelenterata, act- ing as organs of oHense and defense. These bodies are imbedded in the outer cellular layer or ectoderm of cwlenterates. A nematocyst is an oval, tough capsule, tilled with a clear fluid, and invaginated at one end in the form of a hollow process which is prolonged into a long coiled hol- low thread. The entire structure is developed in an interstitial cell called a cnidoblast, which, as it approaches maturity, migrates toward the sur- face and becomes imbedded in one of the large ectoderm cells. At one point on its surface the cnidoblast is produced into a delicate proto- plasmic process, the cnidocil or 'trigger-hair.' Any small animal on coming in contact with the lasso-cells of a jellyfish is stung, benumbed, or poisoned by tliem. Upon contact with one or many of these lasso-cells in the tentacles of a jellyfish or hydra, or a physalia, the cnidoblast suddenly contracts, and the pressure upon the stinging capsule causes an instantaneous eversion of the thread, at the base of which are minute sharp barbs. The threads also convey a poison- ous fluid, which benumbs the victim. In this way sea-anemones and coral polyps obtain their fooil, paralyzing and thus capturing quite large animals, even young fishes. These poison lasso- cells also occur in certain Protozoa, molluslcs, and in sponges, and in a modified form exist in the skin of certain worms, both terrestrial and aquatic. They are in these worms minute stift' rods, either coiled up in an irregularly spiral manner, or short and straight, contained in oval cells. They are shot out in great numbers when the animal is irritated, but are not retractile, being in'ojected clear from the skin. That they are true nettling organs is proved by the fact that nn toiiehing the worms with the tongue they cause a tinglirtg sensation. See illustration under Ca I,EXTERAT.. NEMATODA. A class of the phylum Nema- tlielminthcs (q.v. ). mostly parasites, but many others are extremely abundant in both fresh anil salt water. They are the roundworms (q.v.) and a familiar examjile is found in Ascaris (q.v.). They are ranked in two orders: Nrnintnidra. in which the coelom is not lined by epithelium, and Oordioidca, in wliieh it is so lined. See Haib- woK.M ; i:.MAriit:i..iiNTiiEs. NEMATOGr'NATHI (Neo-Lat. nom. pi., from Gk. frji^a, nfma, thread + yvdOoi, t/nathos, jaw). An order of lishes. See Catfisu; com- jjare PLiitxusi'o.Nuvi.i. NEMATOPHYTON (Xeo-Lat., from Gk. yrjfia, iiciiia, thread + <j>vT6y, jiliylon, plant). A gigantic fossil alga found in rocks of Devonian age in the Eastern United States and Canada. The stem is of great size, often 40 feet long by 2 to 3 feet in diameter, and resembles the trunk of a tree to such extent that it w^as originally supposed to be the trunk of a conifer. This re- semblance led Dawson to name it Prototaxites or ancestral yewtree. The cellular structure is that of an alga. Several large trunks were un- covered near Slonroe, Orange County, N. Y., dur- ing 1S97 to 1899. The type species is Nematopk- ylon Logani. NEMATJ'SUS. An ancient town of Gallia Xarbonensis, now NImes (q.v.). NEMCOVA, nyem'tso-va, Bozena (1820-62). A Czech novelist, born in Vienna. She lived in Bohemia for several years, making a study of the life in its villages. One of her novels on this subject, Babicka ("Little Grandmother," 1855), is especially well known. It has frequently been translated into foreign languages, and into Eng- lish by Gregor in 1891. Her other works include ICarla ("Charlotte," 1856) and Pohor.slcd vrsnice ('•The Village in the Jlountains." 1856). Her contributions to the study of Bohemian and Hun- garian folk-lore in the volumes ydroditi bdchorhy a povi-sti (1845-46) and Sloven-ikt' pohadky a poi-csti ("Slovak Folk Tales," 1858) are valu- able. Her complete works, Sebranc spisy, were published in 1862-63. NE'MEA (Lat., from Gk. XcM^a). The an- cient name of a well-wooded valley of Argolis, in the Peloponnesus, between Cleonie and Phlius. It lies north and south, and is from two to three miles long, and more than half a mile broad. In it there was no town but a sacred inclosure and temple of Zeus, of which three columns are still standing, while the others lie where they have been thrown by earthquakes. The valley was the seat of one of the four great national festivals of the Greeks — the Ncmean (lames, which were cele- brated in mid-summer every two years, at the beginning of the second and fourth year of each OlTOipiad. The first of the historical period seems to have been held in B.C. 573, though legend as- cribed the foundation of the games to the seven heroes on their march against Thebes, or to Hercules. The games consisted of the usiial athletic contests, horse-racing, and a competition for players on the cithara. The prize was a palm branch and crown of parsley. KTEM'ERTIN'EA (Xeo-Lat.. from Gk. Nw<'/>- Trjs, ncmcrlr.s. name of a Xereid, from vrineprrit, nemerfes, unerring, from v^-, me-, not + anapTdveiv, hamartanein. to miss). A class of flatworms easily distinguished from the Platodes by the proboscis and the presence of an anis. They are also remarkable for the prodi- gious length attained by some of the species, which, in the most extended state, is 10 or 12 feet, and one (I.iiiuf: lonriinaimun) reaches 90 feet. But the animal which so stretches itself out is capable of suddenly contracting itself to a