Seite - 165 - in The Origin of Species
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Text der Seite - 165 -
SPECIFIC CHARACTERS HIGHLY VARIABLE 1G5
have repeatedly noticed in works on natural history, that
when an author remarks with surprise that some important
organ or part, wliich is generally very constant throughout
a large group of species, differs considerably in closely
allied species, it is often variable in the individuals of the
same species. And this fact shows that a character, which
is generally of generic value, when it sinks in value and
becomes only of specific value, often becomes variable,
though its physiological importance may remain the same.
Something of the same kind applies to monstrosities: at
least Is. Geoffroy St. Hilaire apparently entertains no doubt,
that the more an organ normally differs in the different spe-
cies of the same group, the more subject it is to anomalies
in the individuals.
On the ordinary view of each species having been inde-
pendently created, why should that part of the structure,
which differs from the same part in other independently
created species of the same genus, be more variable than
those parts which are closely alike in the several species?
I do not see that any explanation can be given. But on the
view that species are only strongly marked and fixed varie-
ties, we might expect often to find them still continuing to
vary in those parts of their structure which have varied
within a moderately recent period, and which have thus
come to differ. Or to state the case in another manner :—
the points in which all the species of a genus resemble each
other, and in which they differ from allied genera, are called
generic characters; and these characters may be attributed
to inheritance from a common progenitor, for it can rarely
have happened that natural selection will have modified sev-
eral distinct species, fitted to more or less widely different
habits, in exactly the same manner : and as these so-called
generic characters have been inherited from before the
period when the several species first branched off from their
common progenitor, and subsequently have not varied or
come to differ in any degree, or only in a slight degree, it is
not probable that they should vary at the present day. On
the other hand, the points in which species differ from other
species of the same genus are called specific characters; and
as these specific characters have varied and come to differ
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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