XIV 
CONTENTS 
CHAPTER XIV 
FUNDAMENTAL 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 
