Seite - 272 - in The Origin of Species
Bild der Seite - 272 -
Text der Seite - 272 -
272 ORIGIN OF SPECIES
as large as the cuckoo. That the small size of the egg is a
real case of adaptation we may infer from the fact of
the non-parasitic American cuckoo laying full-sized eggs.
Thirdly, that the young cuckoo, soon after birth, has the in-
stinct, the strength, and a properly shaped back for ejecting
its foster-brothers, which then perish from cold and hunger.
This has been boldly called a beneficial arrangement, in order
that the young cuckoo may get sufficient food, and that its
foster-brothers may perish before they had acquired much
feeling !
Turning now to the Australian species; though these birds
generally lay only one egg in a nest, it is not rare to find two
and even three eggs in the same nest. In the Bronze cuckoo
the eggs vary greatly in size, from eight to ten lines in length.
Now if it had been of an advantage to this species to have
laid eggs even smaller than those now laid, so as to have de-
ceived certain foster-parents, or, as is more probable, to have
been hatched within a shorter period (for it is asserted that
there is a relation between the size of eggs and the period of
their incubation), then there is no difficulty in believing that
a race or species might have been formed which would have
laid smaller and smaller eggs; for these would have been
more safely hatched and reared. Mr. Ramsay remarks that
two of the Australian cuckoos, when they lay their eggs in
an open nest, manifest a decided preference for nests con-
taining eggs similar in colour to their own. The European
species apparently manifests some tendency towards a similar
instinct, but not rarely departs from it, as is shown by her
laying her dull and pale-coloured eggs in the nest of the
Hedge-warbler with bright greenish-blue eggs. Had our
cuckoo invariably displayed the above instinct, it would as-
suredly have been added to those which it is assumed must
all have been acquired together. The eggs of the Australian
Bronze cuckoo vary, according to Mr. Ramsay, to an ex-
traordinary degree in colour; so that in this respect, as well
as in size, natural selection might have secured and fixed any
advantageous variation.
In the case of the European cuckoo, the offspring, of the
foster-parents are commonly ejected from the nest within
three days after the cuckoo is hatched; and as the latter at
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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