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VENUSIA (mod. Venosa, q.v.)

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Originally appearing in Volume V27, Page 1015 of the 1911 Encyclopedia Britannica.
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VENUSIA (mod. Venosa, q.v.), an ancient city of Apulia, Italy, on the Via Appia, about 6 m. S. of the river Aufidus (Ofanto), and not far from the boundary of Lucania (hence Horace describes himself as " Lucanus an Apulus anceps, nam Venusinus arat finem sub utrumque colonus "). It was taken by the Romans after the Samnite war of 291 B.C., and became a colony at once, no fewer than 20,000 men being sent there, owing to its military importance. Throughout the Hannibalic wars it remained faithful to Rome, and had a further contingent of colonists sent in 200 B.C. to replace its losses in war. Some coins of Venusia of this period exist. It took part in the Social War, and was recaptured by Quintus Metellus Pius; it then became a municipium, but in 43 B.C. its territory was assigned to the veterans of the triumvirs, and it became a colony once more. Horace was born here, the son of a freedman, in 65 B.C. It remained an important place under the Empire as a station on the Via Appia, though Mommsen's description of it (Corp. Inscr. Lat. ix. p. 45) as having branch roads to Equus Tuticus and Potentia, and Kiepert's maps annexed to the volume, do not agree with one another. Remains of the ancient city walls and of an amphitheatre still exist, and a number of inscriptions have been found there. Jewish catacombs with inscriptions in Hebrew, Greek and Latin show the importance of the Jewish population here in the 4th and 5th centuries after Christ. (T. As.) VENUS'S FLY-TRAP (Dionaea muscipula), a remarkable insectivorous plant, a native of North and South Carolina, first described in 1768 by the American botanist Ellis, in a letter to Linnaeus, in which he gave a substantially correct account of the structure and functions of its leaves, and even suggested the probability of their carnivorism. Linnaeus declared it the most wonderful of plants (miraculum naturae), yet only admitted that it showed an extreme case of sensitiveness, supposing that the insects were only accidentally captured and subsequently allowed to escape. The insectivorous habit of the plant was subsequently fully investigated and described by Charles Darwin in his book on insectivorous plants. The plant is a small herb with a rosette of radical leaves with broad leaf-like footstalks. Each leaf has two lobes, standing at rather less than a right angle to each other, their edges being produced into spike-like processes (fig. I). The upper surface of each lobe is covered with minute circular sessile glands, each consisting of from 20 to 30 cells filled with purplish fluid; it bears also three fine-pointed sensitive bristles arranged in a triangle (fig. 3). These contain no fibro-vascular bundles, but present an articulation near their bases, which enables them to bend parallel to the surface of the leaf when the lobes close. When the bristles are touched' by an insect the lobes close very sharply upon the hinge-like midrib, the spikesinterlock, and the insect is imprisoned (fig. 2). If very minute, and so not worth digesting, it is able to escape between the interlocked spines; nitrogenous matter, FIG. 1.—Leaf of Venus's Fly-Trap (Dionaea to pour out an acid muscipula), viewed laterally in its ex- secretion containing panded state, slightly enlarged. (After a ferment or enzyme, Darwin.) similar to that ex- creted by the leaves of the sundew, which rapidly dissolves the soft parts of the insect. This is produced in such abundance that, sure, a singular difference in evident relation to the habits of the two plants. Like the leaves of Drosera, however, those of Dionaea are completely indifferent to wind and rain. The surface of the blade is very slightly sensitive; it may be roughly handled or scratched with-out causing movement, but closes when its surface or midrib is deeply pricked or cut. Irritation of the triangular area on each lobe enclosed by the sensitive bristles causes closure. The footstalk is quite in-sensitive. Inorganic or non-nitrogenous bodies, placed on the leaves without touching the sensitive bristles, do not excite movement, but nitrogenous bodies, if in the least degree damp, cause after several hours the lobes to close slowly. So too the leaf which has closed over a digestible body applies a gradual pressure, which serves to bring the glands on both sides into contact with the body. Thus we see that there are two kinds of movement, adapted for different purposes, one rapid, excited me- If the orbit of Venus lay in the plane of the ecliptic, it would be seen to pass over the disk of the sun at every inferior conjunction. Transits But the inclination of the orbit, 3° 36', is so large that a of Venus. transit is seen only when the earth and Venus pass a node of the orbit at nearly the same time. The earth passes the line of nodes about the 7th of June and the 7th of December of each year. The date of passage is about a day later in each successive more usually, how-ever, it is retained between the lobes, which gradually but firmly compress it, node near enough to these dates to be until its form is dis- in of The tinguishable from ur times a period 243 years. without. The leaf 1518 to 2012 shows the law of recur- thus forms itself into 1769 June 3. a temporary stomach, December 1874 9. and the glands, 7. 1882 December 6. hitherto dry, com- 4. 2004 June 8. mence, as soon as 2012 June 6. excited by the ab- sorption of a trace of when Darwin made a small opening at the base of one lobe of a leaf which had closed over a large crushed fly, the secretion continued to run down the footstalk during the whole time—nine days—during which the plant was kept under observation. The closing of the leaf is due to a redistribution of water in the cells brought about by a change in the protoplasm which follows the Live bristles. Though the bristles are exquisitely sensitive stimulation of the sensi- FIG. to the slightest contact with solid bodies, yet they are far less sensitive that' those of the sundew (Drosera) to prolonged pres- B 2.-Leaf of D. muscipula closed over Insect. A, viewed from the side; B, from above. chanically, the other slow, excited s. chemically. Leaves made to close over insoluble bodies reopen in less FIG. 3.—A, sensitive bristle than twenty-four hours, and are and glands of D. muscipula; ready, even before being fully ex- B glands. paneled, to shut again. But if they have closed over nitrogen-yielding bodies, they remain closely shut for many days, and after re-expanding are torpid, and never act again, or only after a considerable time. Even in a state of nature, the most vigorous'leaves are very rarely able to digest more than twice, or at most thrice, during their life. VENUS'S LOOKING GLASS, a popular garden name for Campanula Speculum (or Specularia Speculum), from the old name for the plant, Speculum Veneris. It is a common cornfield plant in the south of Europe, and is grown in gardens on account of its brilliant purple flowers.
End of Article: VENUSIA (mod. Venosa, q.v.)
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