EVIL. 321 EVOLUTION. EVIL, King's. See Scrofula. EVIL EYE. See Maoic; Superstition; WITCHCRAFT. EVIL-MERODACH, eMl-me-ro'dak (the biblical form of the Babylonian Avel-Marduk, <>r Lmel-Marduk, man of Marduk). A king of Ba- bylonia, the sun and successor of Nebuchadnezzar, who, after a reign of less than a year (B.C. 561- 560), was [ >tt 1 i" death by his brother, Neriglis- sar (i.e. Nergal-shar-usur, "<) Nergal! protecl the King"). He is referred I" in 11. Kings xxv. •27 as having liberated Jehoiachim, King of Judah, in the 37th year of his captivity. No cuneiform inscriptions throwing light on Evil- Merodach's reign have 1 n found, though his name appears on some contract tablets. EVOLUTE AND INVOLUTE. The evolute of any curve is the locus of the centre of its osculating circle; i.e. of the centre of the curvature (see Osculating Circle); and rela- tive to its evolute, the curve is called the involute. The following example will show the relation be- tween these curves. If on any curve, as the circle in the figure, a string be closely wrapped, fast- ened at one end and free at the other, and if the string lie unwound from the curve, being kept taut, the curve traced by a pencil fixed to the free end of the string is the involute of that curve from which the string is unwound. The given curve is the evolute of the curve thus traced. This explains the two names. The normal to the involute at any point is a tan- gent to the evolute, as the construction suggests; and the difference in length between any two radii of curvature to the involute is equal to the length of the arc of the evolute inter- cepted between them. To Huygens (1673), who was among the first to investigate curves of this kind, is due the name evolute. He discovered that the evolute of the common cycloid (q.v.) is another cycloid equal to the first. The work in which these discussions occur is Huygens, Horo- logium Oscillatorium (Paris, 1673). See Curves. EVOLUTION (Lat. evolutio, from rrolrcrc. to unroll, from e, out + volvere, to roll; con- nected with Goth, walwjan, AS. weaVvoian, I wallow). The evolution theory, in its broad aspect, undertakes to explain tl "igin oi the universe, of all created things material and im material; and re especiallj the origin of our own planet, together w ith. the plants and animals living ami extinct, including man, his physical and mental nature. Applied to living beings we use the expressions 'organic evolution,' 'theorj of descent,' 'origin of species,' 'transformation oi species,' or '1 rmism.' The theory of de scent is supported bj a range of facts as wide the number and variety of forms of life, the pi cies of plants and animals, living or fossil, enter ing into the millions. To appreciate properly the facts and arguments on which the theor based one must be familiar with at leas! the elements of all the natural sciences, especially botany, zoology, and geology, and nave done some original work on a group of organisms, beside having some degree of sympathy with the a and methods of natural science. It should be home in mind that in this single word evolution is comprised a study of the i le of action of that vast complex of natural conditions which has resulted in the formation of the stars and planets, and in the stocking of our earth with plants and animals each after their kind. Evolution in general is based ( 1 ) on the unity of action of the processes of nature. We mean by the word •nature' everything which has been generated, produced, or created. This, from a philosophical standpoint, implies an infinite power, or Creator, outside of and yet immanent in the material world, working by natural laws in and through matter, mind, and spirit. (2) The theory of descent, or organic evolution, is based on the principle of the unity of organiza- tion in plants and animals; (3) on the fact that the living substance known as protoplasm is the physical basis of life: (4) on the fact that all movements in the plant or animal body are due to the contractility of protoplasm; and (5) to the fact that all plants and animals arise from germs, seeds, or eggs. This does not exclude the view that the first germ of life — the primitive- bit of protoplasm — arose by spontaneous genera- 1 ion. Definition and Classification of Evolu- tion. As will he seen by the historic summary at the end of this article, attempts have been made since the days of Empedocles and of Aris- totle to explain the origin of the universe. The word 'evolution' originally was applied to such phenomena as that of the unfolding of a flower, or the development of an animal, and was used by Haller, Bonnet, and other-, in speaking of the metamorphoses of the butterfly or frog. As a name for what we call evolution Wolff prop in 175!) the word 'epigenesis,' and applied it to the mode of growth and development of the vertebrate embyro. See Epigenesis. But for the modern use of the word -evolution' we are indebted to Mr. Herbert Spencer. In his Principles of Biology (London, ed. of 1900) "the theory of organic evolution first found philo- sophic, as distinguished from merely scientific expression" ("( isborn ). It would be, perhaps, pref- erable to say that he used the word both in a philosophic and scientific sense. He give- us this highly generalized definition: "Evolution is an integration of matter and concomitant-dissipation of motion, during which the matter passes from
