Seite - 505 - in The Origin of Species
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Text der Seite - 505 -
RECAPITULATION AND CONCLUSION 505
intermediate links in any one formation less likely. Local
varieties will not spread into other and distant regions until
they are considerably modified and improved; and when they
have spread, and are discovered in a geological formation,
they appear as if suddenly created there, and will be simply
classed as new species. Most formations have been inter-
mittent in their accumulation; and their duration has prob-
ably been shorter than the average duration of specific forms.
Successive formations are in most cases separated from each
other by blank intervals of time of great length; for fos-
siliferous formations thick enough to resist future degrada-
tion can as a general rule be accumulated only where much
sediment is deposited on the subsiding bed of the sea. Dur-
ing the alternate periods of elevation and of stationary level
the record will generally be blank. During these latter
periods there will probably be more variability in the forms
of life
; during periods of subsidence, more extinction.
With respect to the absence of strata rich in fossils beneath
the Cambrian formation, I can recur only to the hypothesis
given in the tenth chapter ; namely, that though our conti-
nents and oceans have endured for an enormous period in
nearly their present relative positions, we have no reason to
assume that this has always been the case
; consequently for-
mations much older than any now known may lie buried be-
neath the great oceans. With respect to the lapse of time
not having been sufficient since our planet was consolidated
for the assumed amount of organic change, and this objection,
as urged by Sir William Thompson, is probably one of the
gravest as yet advanced, I can only say, firstly, that we do
not know at what rate species change as measured by years,
and secondly, that many philosophers are not as yet willing
to admit that we know enough of the constitution of the uni-
verse and of the interior of our globe to speculate with safety
on its past duration.
That the geological record is imperfect all will admit ; but
that it is imperfect to the degree required by our theory, few
will be inclined to admit. If we look to long enough intervals
of time, geology plainly declares that species have all
changed; and they have changed in the manner required by
the theory, for they have changed slowly and in a graduated
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Buch The Origin of Species"
The Origin of Species
- Titel
- The Origin of Species
- Autor
- Charles Darwin
- Verlag
- P. F. Collier & Son
- Ort
- New York
- Datum
- 1909
- Sprache
- englisch
- Lizenz
- PD
- Abmessungen
- 10.5 x 16.4 cm
- Seiten
- 568
- Schlagwörter
- Evolutionstheorie, Evolution, Theory of Evolution, Naturwissenschaft, Natural Sciences
- Kategorien
- International
- Naturwissenschaften Biologie
Inhaltsverzeichnis
- EDITOR'S INTRODUCTION 5
- AN HISTORICAL SKETCH of the Progress of Opinion on the Origin of Species 9
- INTRODUCTION 21
- Variation under Domestication 25
- Variation under Nature 58
- Struggle for Existence 76
- Natural Selection; or the Survival of the Fittest 93
- Laws of Variation 145
- Difficulties of the Theory 178
- Miscellaneous Objections to the Theory of Natural Selection 219
- Instinct 262
- Hybridism 298
- On the Imperfection of the Geological Record 333
- On the Geological Succession of Organic Beinss 364
- Geographical Distribution 395
- Geographical Distribution - continued 427
- Mutual Affinities of Organic Beings: Morphology: Embryology: Rudimentary Organs 450
- Recapitulation and Conclusion 499
- GLOSSARY 531
- INDEX 541