Variation On the hereditary tendency Causes of Variation On Selection Crossing Breeds Whether our domestic races have descended from one or more wild stocks Limits to Variation in degree and kind In what consists Domestication--Summary CHAPTER II 81-111 ON THE VARIATION OF ORGANIC BEINGS IN A WILD STATE; ON THE NATURAL MEANS OF SELECTION; AND ON THE COMPARISON OF DOMESTIC RACES AND TRUE SPECIES. Variation Natural means of Selection Differences between "Races" and "Species":-first, in their trueness or variability Difference between "Races" and "Species" in fertility when crossed Causes of Sterility in Hybrids Infertility from causes distinct from hybridisation Points of Resemblance between "Races" and "Species" External characters of Hybrids and Mongrels Summary Limits of Variation CHAPTER III 112-132 ON THE VARIATION OF INSTINCTS AND OTHER MENTAL ATTRIBUTES UNDER DOMESTICATION AND IN A STATE OF NATURE; ON THE DIFFICULTIES IN THIS SUBJECT; AND ON ANALOGOUS DIFFICULTIES WITH RESPECT TO CORPOREAL STRUCTURES. Variation of mental attributes under domestication Hereditary habits compared with instincts Variation in the mental attributes of wild animals 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