PREFACE DURING the fourteen months preceding the date on which this volume is issued I have devoted all available time to work connected with the three inspiring anniversaries of July 1, 1908, Feb. 12, 1909, and Nov. 24, 1909. With all diffidence I have chosen the date which closes this period of work, as the day of publication. It may help in some small degree to keep in remembrance the birthday of a mighty epoch in the history of thought. The first Section of this book attempts to give a brief account ofthe history which led up to and followed the publication of the theory of Natural Selection and the Origin of Species. Darwins sure scientific insight, and his views on evolution by mutation, briefly treated in this Section, receive further consideration in Appendices A and B. The confusion of thought threatened by the unintentional but most unfortunate mis- representation of de Vriess term, fluctuating variability, is pointed out in a footnote and further considered in Appendix D. I have given at the end of this Appendix a very brief account of certain phases of thought, during the past half century, on the variations forming the material out of which the steps of evolutionary progress have been supposed to be built. The influence of Darwins personality upon the intellectual revolution of the past fifty years is considered in the second Section. The wide- spread misunderstanding of the changes which Darwin describes in his own mind, and the consequent injustice to scientific men generally, and especially to Darwin himself, not only form the subject of argument and protest in this Section, but also occupy nearly all the brief third Section, part of the seventh, and the whole ofAppendix C. The unfortunate misinterpretations referred to above require, for their complete and final refuta- tion, the collection from Darwins correspondence of a large number of passages bearing upon health. These, placed together, may convey to the hasty reader an entirely wrong impression of Darwins heroic spirit, and I therefore trust that the words on p. 216 will be remembered whenever such passages may be read. In the fourth Section the relationship ofDarwin to the two ancient English Universities, and especially to his own University of Cambridge, is very briefly considered. The fifth Section is concerned with one of the first and still perhaps the most striking of the interpretations that have sprung from the theory of Natural Selection. The subject, the Value of Colour in the Struggle for Life, is treated histori- cally. Darwins own hypotheses and discoveries in this line, and his keen interest in the hypotheses and discoveries of others are especially considered here and also in part of the seventh Section. The sixth Section deals with Mimicry, the most arresting of all the uses which colour may subserve in the struggle for existence...