Principles of Selection applicable to instincts
Difficulties in the acquirement of complex instincts by Selection
Difficulties in the acquirement by Selection of complex corporeal
structures

PART II

ON THE EVIDENCE FAVOURABLE AND OPPOSED TO THE VIEW
THAT SPECIES ARE NATURALLY FORMED RACES, DESCENDED
FROM COMMON STOCKS.

CHAPTER IV 133-143

ON THE NUMBER OF INTERMEDIATE FORMS REQUIRED ON THE
THEORY OF COMMON DESCENT; AND ON THEIR ABSENCE
IN A FOSSIL STATE

CHAPTER V 144-150

GRADUAL APPEARANCE AND DISAPPEARANCE OF SPECIES.

Gradual appearance of species
Extinction of species

CHAPTER VI

ON THE GEOGRAPHICAL DISTRIBUTION OF ORGANIC BEINGS
IN PAST AND PRESENT TIMES.

SECTION FIRST 151-174

Distribution of the inhabitants in the different continents
Relation of range in genera and species
Distribution of the inhabitants in the same continent
Insular Faunas
Alpine Floras
Cause of the similarity in the floras of some distant mountains
Whether the same species has been created more than once
On the number of species, and of the classes to which they belong
in different regions

SECOND SECTION 174-182

Geographical distribution of extinct organisms
Changes in geographical distribution
Summary on the distribution of living and extinct organic beings

SECTION THIRD 183-197

An attempt to explain the foregoing laws of geographical
distribution, on the theory of allied species having a
common descent
Improbability of finding fossil forms intermediate between
existing species

CHAPTER VII 198-213

ON THE NATURE OF THE AFFINITIES AND CLASSIFICATION
OF ORGANIC BEINGS.

Gradual appearance and disappearance of groups
What is the Natural System?
On the kind of relation between distinct groups
Classification of Races or Varieties
Classification of Races and Species similar
Origin of genera and families

CHAPTER VIII 214-230

UNITY OF TYPE IN THE GREAT CLASSES; AND
MORPHOLOGICAL STRUCTURES.

Unity of Type
Morphology
Embryology
Attempt to explain the f