Even the very brief sketch of the subject here given suggests the idea of _purpose_ in a world so precisely and uniquely adapted to develop organic life, and to support that life during the countless ages required for the completed evolution of man. But that suggestion becomes a logical induction when the whole of the available evidence is set forth, as I have attempted to set it forth in my work on “Man’s Place in the Universe.” I have there shown not only that the cumulative evidence for the earth being the only supporter of a fully-developed organic life within the solar system is irresistible, but that there is some direct, and much more indirect, evidence that this uniqueness extends to the whole stellar universe; and it is certain that no particle of _direct_ evidence for the existence of organic life elsewhere has been, or is likely to be, adduced. I have also shown (in an appendix to the second edition of my book) that the purely biological argument for the uniqueness of the development of man--as the culminating point of one line of descent throughout the diverging ramifications of the animal kingdom--is overwhelmingly strong; hence the logical conclusion from the whole of the evidence is that man is the one supreme product of the whole material universe. My object in the present essay has been limited to showing that, besides and beyond the special adaptations of the various kinds of animals and plants to their special environments, there exist in the earth as a planet, in its various physical and cosmical relations, a whole series of adaptations of a very remarkable character which, so far as we can judge, are essential to its function as a life-producing world. The study of these adaptations, therefore, may be considered to be appropriate here, as constituting a preliminary chapter in the natural history of the Earth and of Mankind. ALFRED RUSSEL WALLACE [Illustration: IN THE DAYS OF THE SEA MONSTERS Reproduced from a plate in Hawkins’ “Book of the Great Sea Dragons.” ] THE BEGINNING OF LIFE ON THE EARTH BY DR. C. W. SALEEBY [Sidenote: The Earth Without Life]