CONTENTS xiii 



of additional facts bearing on insect fertilisation — Fertilisation of 

 flowers by birds— Self-fertilisation of flowers — Difficulties and con- 

 tradictions — Intercrossing not necessarily advantageous — Supposed 

 evil results of close interbreeding — How the struggle for existence 

 acts among flowers — Flowers the product of insect agency — Concluding 

 remarks on colour in nature .... Pages 301-337 



CHAPTER XII 



THE GEOGRAPHICAL DISTRIBUTION OF ORGANISMS 



The facts to be explained — The conditions which have determined dis- 

 tribution — The permanence of oceans — Oceanic and continental areas 

 — Madagascar and New Zealand — The teachings of the thousand- 

 fathom line — The distiibution of marsupials — The distribution of 

 tapirs — Powers of dispersal as illustrated by insular organisms — Birds 

 and insects at sea — Insects at gi'eat altitudes — The dispersal of plants 

 — Dispersal of seeds by the wind — Mineral matter carried by the wind 

 — Objections to the theory of wind-dispersal answered — Explanation 

 of north temperate plants in the southern hemisphere — No proof of 

 glaciation in the tropics — Lower temperature not needed to explain 

 the facts — Concluding remarks .... 338-374 



CHAPTER XIII 



THE GEOLOGICAL EVIDENCES OF EVOLUTION 



What we may expect — The number of known species of extinct animals — 

 Causes of the imperfection of the geological record — Geological 

 evidences of evolution — Shells — Crocodiles — The rhinoceros tribe — 

 The pedigree of the horse tribe — Development of deer's horns — Brain 

 development — Local relations of fossil and living animals — Cause 

 of extinction of large animals — Indications of general progress in 

 plants and animals — The progressive development of plants — Possible 

 cause of sudden late appearance of exogens — Geological distribu- 

 tion of insects — Geological succession of vertebrata — Concluding 

 remarks ....... 375-409 



