of a thing so as to change its original purpose and adapt it to other uses. Adaptation in biology is the power and process by which an organism or species of animals or plants changes and becomes modified, so as to suit the conditions of its life. In other words it is the adjustment, or favourable reaction, of the living world to its environment, the advantageous variation of animals and plants under changed conditions. The term now includes both that which is hereditary and that which is acquired. The powers of lower forms of life to adapt themselves to changes of environment are limited, and frequently, when the conditions vary suddenly, they are either arrested in their development or die altogether.—In literature it is the process by which an author modifies the work of another not in its essence but in its form and details, either in the original or in a foreign language.
A′dar, the twelfth month of the Hebrew sacred and sixth of the civil year, answering to part of February and part of March.
Adda (ancient Addua), a river of North Italy, which, descending from the Rhætian Alps, falls into Lake Como, and leaving this joins the Po, after a course of about 170 miles. On the banks of the Adda Napoleon won the battle of Lodi in 1796.
Adda, a species of lizard, more commonly called Skink.
Ad′dax, a species of antelope (Hippotrăgus nasomaculātus) of the size of a large ass, with much of its make. The horns of the male are about 4 feet long, beautifully twisted into a wide-sweeping spiral of two turns and a half, with the points directed outwards. It has tufts of hair on the forehead and throat, and large broad hoofs. It inhabits the sandy regions of Nubia and Kordofan, and is also found in Caffraria.
Adder, a name often applied to the common viper as well as to other kinds of venomous serpents. See Viper.
Adder-pike (Trachīnus vipĕra), a small species of the weever fish, called also the Lesser Weever or Sting-fish. See Weever.
Adder-stone, the name given in different parts of Britain to certain rounded perforated stones or glass beads found occasionally, and supposed to have a kind of supernatural efficacy in curing the bites of adders. They are believed to have been anciently used as spindle-whorls, that is, a kind of small fly-wheels to keep up the rotatory motion of the spindle.
Adder's-tongue, a species of British fern (Ophioglossum vulgātum), whose spores are produced on a spike, supposed to resemble a serpent's tongue.