xiv CONTENTS 



CHAPTER XIV 



FUNDAJIENTAL PROBLEMS IN RELATION TO VARIATION 

 AND HEREDITY 



Fundamental difficulties and objections — Mr. Herbert Spencer's factors 

 of organic evolution — Disuse and effects of withdrawal of natural 

 selection — Supposed effects of disuse among wild animals — Difficulty 

 as to co-adaptation of parts by variation and selection — Direct action 

 of the environment — The American school of evolutionists — Origin 

 of the feet of the ungulates — Supposed action of animal intelligence — 

 Semper on the direct influence of the environment — Professor Geddes's 

 theory of variation in plants — Objections to the theory — On the 

 origin of spines — Variation and selection overpower the effects of use 

 and disuse — Supposed action of the environment in imitating varia- 

 tions — Weismann's theory of heredity — The cause of variation — The 

 non-heredity of acquired characters — The theory of instinct — Con- 

 cluding remarks ..... Pages 410-444 



CHAPTER XV 



DARWINISM APPLIED TO MAN 



General identity of human and animal structure — Rudiments and varia- 

 tions showing relation of man to other mammals — The embryonic 

 development of man and other mammalia — Diseases common to man 

 and the lower animals — The animals most nearly allied to man — 

 The brains of man and apes — External differences of man and apes — 

 Summary of the animal characteristics of man — The geological 

 antiquity of man— The probable birthplace of man— The origin of 

 the moral and intellectual nature of man — The argument from 

 continuity — The origin of the mathematical faculty — The origin of 

 the musical and artistic faculties — Independent proof that these 

 faculties have not been developed by natural selection — The inter- 

 pretation of the facts — Concluding remarks . . 445-478 



INDEX 479-494 



