CONTENTS 
Xlll 
of additional facts bearing on insect fertilisation—Fertilisation of 
Howers 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 distribution of marsupials — The distribution of 
tapirs — Powers of dispersal as illustrated by insular organisms — Birds 
ami insects at sea — Insects at great 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 .... 338-37 4 
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 
