gated and made mesophytic. In contrast with hydrophytes and xerophytes, the meso-phytes are far richer in leaf-forms. All of the societies which man has formed by his introduction of weeds and culture-plants are mesophytic. Among the more conspicuous mesophyte societies the following may be mentioned: arctic and alpine "carpets," characteristic of high altitudes and latitudes, where the conditions forbid trees, shrubs or even tall herbs; meadows, which are areas dominated by grasses, the prairies being the greatest of meadows; thickets, composed of willow, alder, birch etc., either pure or forming a jungle of mixed shrubs, brambles and tall herbs ; deciduous forests, the pride of the temperate regions, rich in forms and leaf display, with autumnal coloration and annual fall of leaves; and rainy, tropical forests in the regions of trade-winds, heavy rainfall and great heat, where the world's vegetation reaches its culmination and dense growths are developed, composed of all sorts of trees, shrubs and herbs bound together in an inextricable tangle of great vines.

Mesopotamia (mĕs'ō-po-ta'mĭ-), a country in western Asia between the Tigris and Euphrates Rivers, whence its name, meaning "between the rivers." It belongs to the Turkish empire and has an area (including Mosul, Baghdad and Busra) of 143,250 square miles, with a level surface and sandy soil. When irrigated, as it was in ancient times, it is very fertile. Baghdad (population 145,000) is its capital. Mesopotamia to-day has a population of 1,398,200. Since 1515, when it was conquered by the Turks, it has been neglected and has become barren. The present population consists of Arabs and Kurds, who keep herds of camels, sheep and goats, and raise wheat, barley, millet, cotton, tobacco and hemp. Wild hogs, jackals, hyenas and foxes abound, but lions and wild asses have disappeared. The country has belonged to Assyrians, Babylonians,Per-sians, Greeks, Romans, Arabs and Turks, and has often been the battlefield of these great empires. Among its ancient cities were Haran and Nineveh, and among modern ones are Mardin, Mosul and Diarbekir. The excavations are adding much to the knowledge of the region and its early inhabitants. See Assyria, Babylon, Nineveh.

Mesquite (mĕs-kē'f) (Prosopis Juliflord) is a spiny shrub or small tree, found in Texas and throughout the semiarid southwest, of the family Leguminosœ. Its wood is hard and affords a good fuel in limited quantities, while its gum supplies a fair substitute for gum arabic. The long pods offer a sweet, thick, fairly palatable pulp. Bark and wood are used for tanning. The curly mesquite or screw-bean is larger than the common mesquite, although scarcely large enough to be called a tree, growing in company with willows near springs. Its pods are from an inch

to an inch and a half in length and twisted into a rigid cylinder. The beans are eaten by Indians. Certain coarse grasses of the southwest are often called mesquite-grass. They are valuable to stock-men,but of little value when cut.

Messi'ah. The best known and most popular of all oratorios. Composed to biblical text by George Frederick Hndel (1685-1759) in 24 days. First performed in Dublin on Apr. 13, 1742. This work has the advantage arising from the use of some of the most impressive passages of Scripture, upon which it is a true musical commentary. Some of its airs are unequalled for the expression of religious emotion, and many of its choruses are overpowering in their effect upon the hearer who to musical taste unites devotional spirit.

Messina (niĕs-sē'n), the second city and seaport of Sicily, lies on the western shore of the Strait of Messina. The city rises in an amphitheater, its white houses standing in relief against a background of hills. The city, although ancient, has few antiquitie», as it was overrun by armies, nearly destroyed by an earthquake in 1783, and again in 1908. It has one of the finest harbors in the world. The industries are the manufacture of linen, muslin and silk goods, working coral and making fruit-essences; the exports are largely fruits and articles made from fruit, as olive-oil, wine and essences. The city was founded in 732 B. C, and the Carthaginians destroyed it in 39Ŏ B. C. After Carthage was conquered it belonged to the Roman empire, until the Saracens took it in the 9th Christian century. They were expelled in tho nth century by the Normans; and from 1282 to 1713 the Spaniards held it. In 1743 the plague and in 1783 the earthquake completed its ruin. In 1848 it was bombarded by the Neapolitans, and in 1861 was the last place in Sicily to yield to Italy. In the earthquake which occurred Dec. 28, 1908, almost the whole population of 149,778 was wiped out, the dead numbering no less than 60,000, and the injured 80,000. Messina also is a province; area 1,245 square miles; population 568,833.

Metabolism {m-tăb'-lz'm) (in plants), all the chemical processes taking place in the living organism. Some of these processes are constructive, i. e,, the resulting substances are more complex than before ; others are destructive, the resulting substances being simpler than before. Constructive metabolism occurs when a green leaf, acting on carbon dioxide and water under the influence of light, forms sugar, a complex food, and when by further changes this food is built up into living protoplasm But in respiration protoplasm is decomposed, and carbon dioxide and water, with other less known products, are formed. This is destructive metabolism. The products of metabolism are so many as [ almost to defy enumeration. See., for exam-