386 MY LIFE [Chap. 



" The Colours of Animals and Sexual Selection " (in " Natural 

 Selection and Tropical Nature," 1878) and more fully 

 developed in " Darwinism." I am now inclined to think that 

 it accounts for more of the variety and beauty in the animal 

 world than any other purpose yet discovered. 1 



I may here add that I believe I was first to give adequate 

 reasons for the rejection of Darwin's theory of brilliant male 

 coloration or marking being due to female choice. 



6. The general permanence of oceanic and continental 

 areas was first taught by Professor J. D. Dana, the eminent 

 American geologist, and again by Darwin in his " Origin of 

 Species ; " but I am, I believe, the only writer who has 

 brought forward a number of other considerations, geographical 

 and physical, which, with those of previous writers, establish 

 the proposition on almost incontrovertible grounds. My 

 exposition of the subject is given in " Island Life " (chap, vi.), 

 while some additional arguments are given in my " Studies " 

 (vol. i. chap. ii.). The doctrine may be considered as the 

 only solid basis for any general study of the geographical 

 distribution of animals, and it is for this reason that I have 

 made it the subject of my careful consideration. 



7. In discussing the causes of glacial epochs I have 

 adopted the general views of Mr. James Croll as to the 

 astronomical causes, but have combined them with geogra- 

 phical changes, and have shown how the latter, even though 

 small in amount, might produce very important results. In 

 particular I have laid stress on the properties of air and 

 water in equalizing temperature over the earth, while snow 



1 A correspondent, Mr. G. Norman Douglass, writing from the British Embassy, 

 St. Petersburg, in 1894, sent me the following translation of a passage in 

 Schopenhauer's " Die Welt als Wille und Vorstellung (Zur Teleologie) " which 

 curiously anticipates my views : — 



M One accounts for the wonderfully varied and vividly glowing coloration of the 

 plumage of tropical birds, although only in a very general way, by the stronger 

 influence of light between the tropics — as its causa efficiens. As its causa finahs, I 

 should say that these brilliant plumages are the full-dress uniforms by means of 

 which the individuals of the numberless species, often belonging to one and the 

 same genus, recognize each other, so that every male finds its female." 



