THE EVOLUTION OF LIFE ii
dple, namely, the nature of the action, reaction, and interaction of the cosmic and life environment and individual developmental energies with the energies of the heredity substance. The nature of this unknown principle,** which is at present almost entirely beyond the realm of observation and experiment, will, however, be made clearer through the development of our main subject, the origin and evolution of life upon the earth so far as it has been observed up to the present time or so far as it can he legitimately inferred from actual observation.
The Eabth as a Developing Envieonment
In general, our narrative will follow the " unif ormitarian '* method of interpretation first presented in 1788 by Hutton,*' who may be termed the Newton of geology, and elaborated in 1830 by Lyell,*' the master of Charles Darwin. In the spirit of the preparatory work of the great pioneers in geology, such as Hutton, Scrope and Lyell, and of the history of the evolution of the working mechanism of organic evolu- tion, as developed by Darwin and Wallace/^ our inferences as to past processes are founded npon the observation of present processes. The unif ormitarian doctrine is this: present continuity implies the im- probability of past catastrophism and violence of change, either in the inorganic or in the organic world.
We shall consider in order, first, the evolution of the inorganic environment necessary to life; second, the advent of life, what is known of its nature and in regard to the time and the form in which it prob- ably originated ; and third, the evolution of life, its orderly development, the differentiation and adaptation of the various life forms; while thronghont we shall trace the operation of our fundamental biologic law, which involves the action, reaction and interaction of environment and individual development with the forces of heredity.
PRIMOBDIAL ENVIRONMENT — THE LIFELESS EARTH
Let ns first look at the cosmic environment, the inorganic world before the entrance of life. Since 1825, when Cuvier** published his famous "Discours sur les Bevolutions de la Surface du Globe,*' the past history of the earth, of its waters, of the atmosphere, and of the snn — ^the fonr great complexes of inorganic environment — ^has been written with some approach to precision. Astronomy, physics, chem- istry, geology and paleontology have each followed along their respective lines of observation, resulting in some concordance and much discordance of opinion and theory. In general we shall find that opinion fotmded
" See Osborn, H. F., 1909, 1912, 1, 1912, 2.
IS Hntton, James, 1795.
!• Lyell, Charles, 1830.
IT Judd, Jobn W., 1910.
!• Covier, Baron Georges L. C. F. D., 1825.
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