Get this book in print
About this book
My library
Books on Google Play
CHAPTER III.
STRUGGLE FOR EXISTENCE.
--
Its bearing on natural selection—The term used in a wide sense —
Geometrical ratio of increase-Rapid increase of naturalised
animals and plants-Nature of the checks to increase-Compe-
tition universal-Effects of Climate Protection from the
number of individuals - Complex relations of all animals and
plants throughout nature-Struggle for life most severe between
individuals and varieties of the same species; often severe be-
tween species of the same genus- -The relation of organism to
organism the most important of all relations
CHAPTER IV.
NATURAL SELECTION.
Page 63-82
Natural Selection-its power compared with man's selection — its
power on characters of trifling importance—its power at all ages
and on both sexes Sexual Selection - On the generality of inter-
crosses between individuals of the same species-Circumstances
favourable and unfavourable to Natural Selection, namely,
intercrossing, isolation, number of indivíduals — Slow action
Extinction caused by Natural Selection-Divergence of Cha-
racter, related to the diversity of inhabitants of any small area,
and to naturalisation - Action of Natural Selection, through
Divergence of Character and Extinction, on the descendants
from a common parent- Explains the Grouping of all organic
beings-Advance in organisation-Low forms preserved
Objections considered-Indefinite multiplication of species-
Summary
83-147
CHAPTER V.
LAWS OF VARIATION.`
Effects of external conditions-Use and disuse, combined with
natural selection; organs of flight and of vision Acclimatisa-
tion-Correlation of growth-Compensation and economy of
growth-False correlations - Multiple, rudimentary, and lowly
organised structures variable-Parts developed in an unusual
manner are highly variable: specific characters more variable
than generic secondary sexual characters variable-Species of
the same genus vary in an analogous manner - Reversions to
long-lost characters Summary 148-188
CHAPTER VI.
DIFFICULTIES ON THEORY,
Difficulties on the theory of descent with modification-Transitions-
Absence or rarity of transitional varieties-Transitions in habits
of life- Diversified habits in the same species-Species with
habits widely different from those of their allies — Organs of
extreme perfection-Means of transition Cases of difficulty —
Natura non facit saltum - Organs of small importance - Organs
not in all cases absolutely perfect-The law of Unity of Type
and of the Conditions of Existence embraced by the theory of
Natural Selection.. Page 189-226
CHAPTER VII.
-
INSTINCT.
Instincts comparable with habits, but different in their origin -
Instincts graduated — Aphides and ants-Instincts variable
Domestic instincts, their origin-Natural instincts of the cuckoo,
ostrich, and parasitic bees - Slave-making ants-Hive-bee, its
cell-making instinct-Changes of instinct and structure not
necessarily simultaneous - Difficulties on the theory of the
Natural Selection of instincts - Neuter or sterile insects-
Summary . 227-266
CHAPTER VIII.
HYBRIDISM.
Distinction between the sterility of first crosses and of hybrids-
Sterility various in degree, not universal, affected by close inter-
breeding, removed by domestication-Laws governing the sterility
of hybrids-Sterility not a special endowment, but incidental
on other differences — Causes of the sterility of first crosses and of
hybrids - Parallelism between the effects of changed conditions
of life and of crossing-Fertility of varieties when crossed
and of their mongrel offspring not universal-Hybrids and
mongrels compared independently of their fertility - Summary
267-301
CHAPTER IX.
ON THE IMPERFECTION OF THE GEOLOGICAL RECORD.
On the absence of intermediate varieties at the present day-On
the nature of extinct intermediate varieties; on their number-
On the vast lapse of time, as inferred from the rate of deposi-
tion and of denudation · On the poorness of our paleontological
collections - On the denudation of granitic areas On the
intermittence of geological formations - On the absence of
intermediate varieties in any one formation—On the sudden
appearance of groups of species — On their sudden appearance in
the lowest known fossiliferous strata ..
Page 302-337
CHAPTER X.
ON THE GEOLOGICAL SUCCESSION OF ORGANIC BEINGS.
On the slow and successive appearance of new species-On their
different rates of change-Species once lost do not reappear
Groups of species follow the same general rules in their appear-
ance and disappearance as do single species-On Extinction -
On simultaneous changes in the forms of life throughout the
world - On the affinities of extinct species to each other and to
living species - On the state of development of ancient forms-
On the succession of the same types within the same areas
Summary of preceding and present chapter
CHAPTER XI.
GEOGRAPHICAL DISTRIBUTION.
338-375
Means
Present distribution cannot be accounted for by differences in phy-
sical conditions-Importance of barriers- Affinity of the pro-
ductions of the same continent Centres of creation
of dispersal, by changes of climate and of the level of the land,
and by occasional means -Dispersal during the Glacial period
co-extensive with the world
376-413
CHAPTER XII.
GEOGRAPHICAL DISTRIBUTION-continued.
Distribution of fresh-water productions - On the inhabitants of
oceanic islands - Absence of Batrachians and of terrestrial Mam-
mals-On the relation of the inhabitants of islands to those of
the nearest mainland-On colonisation from the nearest source
with subsequent modification Summary of the last and pre-
sent chapter
Page 414-442
CHAPTER XIII.
MUTUAL AFFINITIES OF ORGANIC BEINGS: MORPHOLOGY:
EMBRYOLOGY: RUDIMENTARY ORGANS.
CLASSIFICATION, groups subordinate to groups. -Natural system-
Rules and difficulties in classification, explained on the theory of
descent with modification Classification of varieties-Descent
always used in classification Analogical or adaptive characters
- Affinities, general, complex and radiating-Extinction se-
parates and defines groups-MORPHOLOGY, between members
of the same class, between parts of the same individual-
EMBRYOLOGY, laws of, explained by variations not supervening
at an early age, and being inherited at a corresponding age
- RUDIMENTARY ORGANS; their origin explained-Summary
443-491
CHAPTER XIV.
RECAPITULATION AND CONCLUSION.
Recapitulation of the difficulties on the theory of Natural Selection
- Recapitulation of the general and special circumstances in its
favour-Causes of the general belief in the immutability of
species- How far the theory of natural selection may be
extended-Effects of its adoption on the study of Natural
history-Concluding remarks..
492-525
527-538
INSTRUCTION TO BINDER.
The Diagram to front page 123, and to face the latter part of the
Volume.