ganic 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
variations--Weismann's theory of heredity--The cause of
variation--The non-heredity of acquired characters--The theory
of instinct--Concluding remarks

CHAPTER XV

DARWINISM APPLIED TO MAN

General identity of human and animal structure--Rudiments and
variations 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 interpretation of the facts--Concluding remarks

LIST OF ILLUSTRATIONS

PORTRAIT OF AUTHOR
MAP SHOWING THE 1000-FATHOM LINE
1. DIAGRAM OF VARIATIONS OF LACERTA MURALIS
2. " VARIATION OF LIZARDS
3. " VARIATION OF WINGS AND TAIL OF BIRDS
4. " VARIATION OF DOLICHONYX ORYZIVORUS
5. " VARIATION OF AGELAEUS PHOENICEUS
6. " VARIATION OF CARDINALIS VIRGINIANUS
7. " VARIATION OF TARSUS AND TOES
8. " VARIATION OF BIRDS IN LEYDEN MUSEUM
9. " VARIATION OF ICTERUS BALTIMORE
10. " VARIATION OF AGELAEUS PHOENICEUS
11. " CURVES OF VARIATION
12. " VARIATION OF CARDINALIS VIRGINIANUS
13. " VARIATION OF SCIURUS CAROLINENSIS
14. " VARIATION OF SKULLS OF WOLF
15. "