Page:The New International Encyclopædia 1st ed. v. 05.djvu/209

COLOR. has—i.e. the possession of the property under whatever muniments of title the vendor had, and a right to “tack,” or add, the period of possession to make up the time necessary to gain absolute title by adverse possession. See  COLOR,. The great majority of plants show distinct coloration, especially in aerial or aquatic organs. The absence of color is an index of parasitic or saprophytic life, but it must be borne in mind that many parasites and saprophytes are highly colored. The most common coloring matter in plants is chlorophyll, which manifests itself in various shades of green. Light of some strength has been shown to be necessary for the development of chlorophyll, though recent experiments show that it may develop in various seedlings germinated in perfect darkness, and that the synthesis of carbohydrates may take place vigorously under a dense layer of cork. The presence of plastids and favorable conditions of nutrition are necessary for the proper development of chlorophyll. Yellow coloration in plants is also commonly associated with plastids, and is due to the relative abundance of xanthophyll or carotin present as compared with the true chlorophyll. The phenomenon of yellowness is most common in dying leaves, and is especially well shown in autumn. However, in many young leaves, especially where the nutrition conditions are unfavorable, yellow leaves also appear. Unfavorable nutrition is probably the cause of yellowness in most cases. In dying leaves the part near the veins usually remains green longest. In young leaves the green parts are longer and much better developed internally than are the yellow or white parts.
 * (to property).

Red or blue coloration in plants is not directly associated with plastids, but is due to pigments that are scattered through the cell-sap. The coloring substances are called anthocyans, erythrophyll if red, cyanophyll if blue. Blue colors occur most commonly in flowers, while the reds occur abundantly in leaves, as well as in flowers. The red coloration of leaves has been much discussed in literature, and deserves further mention. While in some plants, as coleus, red colors are more or less permanent, in most cases redness is periodic. Perhaps the three most common examples of color display are: (1) in the young actively growing leaves of seedlings or perennial shoots; (2) in wintering leaves, especially of rosette plants; and (3) in dying leaves, especially in autumn leaves. All kinds of causes have been assigned to account for periodic coloration, but by far the most satisfactory is one proposed by Overton in 1899. He has shown experimentally that an excess of sugar in nutrient solutions causes an early and rich development of color, while an absence of sugar retards this development. In the summer the products of a day's photosynthesis are commonly carried off before another day begins; but in the cool autumn nights this transfer is checked, and sugars accumulated in the leaf unite with tannin substances and cause the production of the pigments. A similar explanation, plus the great flow of sap, would account for red leaves in spring. Mechanical injury, which prevents the carbohydrate transfer, also causes an excess of sugar and gives rise to red colors. Light seems to favor color development, perhaps

because it favors the increased production of carbohydrates.

Much has been said as to the ecological significance of red colors. Stahl and Kay, as a result of experiments, hold that red colors increase the available supply of heat, and thus prolong the leaf activities in fall and enlarge them in spring. Kerner has also held the ‘protective’ theory of color. If red colors do have any such function—and this is by no means proved—it must probably be regarded as quite incidental. In no case can the need for protection be regarded as a cause of the development of pigment, as one might suppose from reading various treatises on the subject of color. See ; und Versuche über das Auftreten von rothem Zellsaft bei Pflanzen,” in Jahrbuch für wissenschaftliche Botanik, vol. xxviii. (Berlin, 1899).  COLORADO, (Sp., colored red) (‘the Centennial State’). A State of the American Union, the twenty-fifth in order of admission. It lies between latitudes 37° and 41° N., and longitudes 102° and 109° W., and is bounded on the north by Wyoming and Nebraska, on the east by Nebraska and Kansas, on the south by Oklahoma Territory and New Mexico, on the west by Utah. Length from east to west, 380 miles; breadth, 275 miles; land area, 103,645 square miles; water area, 280 square miles.
 * . Consult Overton, “Beobachtungen

. Colorado lies upon the great watershed of the continent, and is, after Wyoming, the most elevated State in the Union. A number of the most prominent ranges of the Rocky Mountain system traverse the State in a northerly and southerly direction, spreading magnificently over more than half the surface. The eastern section lies in the plain of the great Mississippi Basin, rising gradually from an elevation of about 3000 feet at the eastern boundary to a considerably higher altitude in the west. In the longitude of Denver and Colorado Springs the surface becomes broken by irregular chains of foot-hills. Back of these rise abruptly the lofty ranges of the Rockies. Entering the State from the north, they are called the Medicine Bow Range, and continue south as the Front Range to Pike's Peak, west of Colorado Springs. This is the most famous mountain in the State, but not the highest, being one of a score that range between 14,000 and 14,500 feet in elevation. West of these ranges are three valleys called North, Middle, and South Parks. North Park is inclosed on the west by the Park Range, and is separated from Middle Park by a ridge, extending from the east to the west, called the Divide. The North Platte River rises on its northern slope; on its southern, the Rio Grande. Between the Middle and South parks the Front Range meets the Saguache, the loftiest of them all. For miles its crest towers above the 13,000-foot level, surmounted by the impressive Holy Cross Peak, the Princeton, Harvard, Yale, and other mountains whose heights exceed 14,000 feet. To the southeast the range is continued in the Sangre de Cristo and Culebra, which extend into New Mexico. West of these latter ranges lies another valley called the San Luis Park, while west of this rise the San Juan Mountains. In the remainder of the western portion of the State there is a confusion of broken mountains, 