TION. As will be seen by the historic summary at the end of this article, attempts have been made since the days of Empedoeles 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 or the development of an animal, and was used by Haller, Bonnet, and others, in speaking of the metamorphoses of the butterfly or frog. As a name for what we call evolution Wolff proposed in 1759 the word 'epigenesis,' and applied it to the mode of growth and development of the vertebrate embyro. See EP [GENESIS.
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" ( Osborn ). It would be, perhaps, pref
erable to say that he used the word both in a philosophic and scientific sense. He gives us this highly generalized definition: "Evolution is an integration of matter and concomitant-dissipation of motion, during which the matter passes from a relatively indefinite incoherent homogeneity, to a relatively definite coherent heterogeneity, and (luring which the retained motion (energy) undergoes a parallel transformation." The es sence of his view is that there is a continual change in the organic world from the homoge neous to the heterogeneous, or from the generalized to the specialized. We are also indebted to Spen cer for the apt expression 'survival of the fittest.' Evolution in general may be divided into (1) inorganic: (2) organic; and (3) mental.