Page:The New International Encyclopædia 1st ed. v. 17.djvu/310

* ROOT. 283 ROOT. ciiith bulb, in water; air roots are constructed for an air niediuni, for instance, the dangling roots of an epiiiliytic orchid; clinging roots are organized for climbing, as in the ivies; prop roots are sent out to support wide-spreading braiiclu-s to enable Fig. 1. ciioss-sECTioN of yucng root. Showing root-hairs with adherent soil-particles. them to spread farther, as in the screw-pine, banyan, etc. Unlike stems, roots bear no leaves or foliar structures, joints (nodes) ; do not in- crease in length by joints, but by continuous multiplication and enlargement of apical cells; and their branches arise from the central woody cylinder. In minute structure roots are still more dis- tinct from stems. (See Histology.) In general the tips bear more or less conspicuous root-caps Fig. 2. PLANTLET. Showing roots and root-hairs. Fig. 3. DIAGRAM OF LONGITUDI- NAL SECTION OF ROOT-TIP. Showing dermatogeu (e). peri- biem ip), pierome {pi), and root- cap (c). composed of hood-like masses of cells, which die and slough off in front, and are renewed from behind (c, Fig. 3). This cap serves to protect the delicate growing tip as the root pushes its way through the soil. Just behind the root-cap are usually very numerous and delicate hairs, which are elongated outgrowths from the epider- mal cells. They increase the absorbing surface of the root and are developed only in the activity absorbing region near the tip. As the rootlet lengthens new root-hairs appear near the tip, and the older ones perish ( Kigs. 1, 2). .lust beneath the root-cap is the group of rapidly <li- viding apical cells, from which all the tissues of the root are derived. .Just behind the apical group the three embryonic regions of the root begin to difl'erentiate (Fig. 3). In the centre is the pierome, an axial mass of cells that tend to elongate. When fully organized this becomes the stele, in which originate the vascular bundles or main conducting strands of the root. Sur- rounding the pierome is the periblcnr, that later becomes the cortex, in roots a very prominent re- gion. The cortex is covered by a single layer of cells, the dennatogeu, that later becomes the epi- dermis. The dermatogen gives rise to the root- cap. In most roots also the epidermis behind the root-cap is replaced by a modified outer layer of the cortex, called the epiblema. Probably the chief anatomical peculiarity of the root is the central and solid woody axis, whose tissues are arranged in a way which distinguishes the root from most stems. Early in the history of peren- nial roots secondary changes occur, that greatly modify the general structure, especially in the appearance of growth rings, and assimilate it to that of stems. See Histology. ROOT. In philology (q.v.), that abstract form of a word which remains after all formative elements have been removed. In strict scientific discussion in Indo-Germanic linguistics a root is regarded as jire-Indo-Germanic; that is, it is a hypothetical word derived not only by omission of all foriuatives, but also by comparison of all cognate words in the Indo-Germanic languages. To speak of Greek, Celtic, or Germanic roots is, therefore, scientifically inaccurate. Roughly speaking fot may be called the root of foot, but properly the root is the hypothetical Indo-Ger- manic form '']>od, as shown by a comparison of Sanskrit pCida, Avesta jiuSa, Armenian otn, Greek ttoCs, Doric Greek ttus, Latin pes. Lith- uanian jHulas, Gothic fotiis, Old High German ftioz, and Anglo-Saxon fot. In all probabil- ity roots never had an actual existence. Consult: Delbriick, Einleitunp in das Sprach- studium (3d ed., Leipzig. 1893) ; Hirt, Indoticr- inaiiischer Ahlaut (Strassburg, 1900); Gabe- lentz, Sprachwissenschaft (Leipzig, 1901) ; Fick, yerglciclieiides Wdi-icrliich der indoijcrmanischc-n Sprachcii (3d ed., Gottingen, 1874-76; 4th ed., 1890 — ) ; Persson, Wurzelerweiterung uiid Wiir- xelcariation (Upsala, 1891). See Philology. ROOT. In music, the lowest tone of any chord in its fundamental position. See Chobd; Har- mony. ROOT. A number or expression resulting from the process of evolution. (See Involution AND Evolution.) Also the values of the un- knowns which satisfy an equation (q.v.) are called the roots of the equation. ROOT, Elihu (1845—). An American lawyer and administrator, born at Clinton, N. Y.. where his father was professor of mathematics in Ham- ilton College, at which Elihu graduated in 1864. He began to practice law in 1867. form- ing partnerships with John N. Strahan in that year, with Willard Bartlett in 1876. and in 1886 with Samuel B. Clarke. Eoot was especially successful as a corporation lawyer and was coun- sel for the Sugar Trust, for New York street rail-