xii CONTENTS. 



CHAPTER IX. 



THE EVIDENCE FROM SECONDARY SEXUAL CHARACTERS CON- 

 TINUED. THE CAUSE OF THE EXCESSIVE MODIFICATION OF 

 MALE CHARACTERS. 



The explanation of Daines Harrington and Wallace Reasons 

 for considering it inadequate Darwin's explanation 

 History of domesticated races shows that this does not go 

 to the root of the matter The view that the male is more 

 exposed than the female to the action of selection A 

 more fundamental explanation is needed This is fur- 

 nished by our theory of heredity Special difficulties 

 ) Summary 207 



CHAPTER X. 



THE EVIDENCE FROM THE INTELLECTUAL DIFFERENCES BE- 

 TWEEN MEN AND WOMEN. . , . 242 



CHAPTER XI. 



THE THEORY OF HEREDITY CONSIDERED AS SUPPLEMENTARY TO 

 THE THEORY OF NATURAL SELECTION. 



Darwin believes that variations are purely fortuitous Natural 

 selection cannot give rise to permanent race modifications 

 unless many individuals vary in nearly the same way, at 

 about the same time The chances against this are very 

 great if variations are fortuitous Argument from North 

 British Review Darwin acknowledges the great weight 

 of this objection It is removed by the theory of heredity 

 The co-ordinated modification of complicated organs 

 The time demanded by Darwin practically infinite- 

 Murphy's argument from the complexity of the eye 

 Herbert Spencer's illustration Our theory removes this 

 difficulty Mr. Conn's objection Saltatory evolution 

 Evidence that it occurs Spike horn buck Ancon and 

 Mauchamp sheep Black-shouldered peacock The the- 

 ory of heredity accounts for saltatory evolution Parallel 

 variation Evidence of its occurrence Evolution of the 

 medusse General and special Homologies 275 



CHAPTER XII. 



RECAPITULATION AND CONCLUSION - 312 



