L'origen de les espècies

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L'ORIGEN DE LES ESPÈCIES.

"Tanmateix, pel que fa al món material, com a mínim podem arribar a dir que els esdeveniments no es produeixen per mitjà d'intervencions puntuals del poder diví, exercit en cada cas particular, sinó mitjançant l'establiment de lleis generals."

Whewell: Tractat de Bridgewater.

"L'únic significat distint de la paraula «natural» és 'establert', 'fix' o 'estable', car les coses naturals exigeixen i pressuposen l'existència d'un agent intel·ligent que les faci naturals, és a dir, que les creï contínuament o en determinats moments, en la mateixa mesura que les coses supernaturals o miraculoses exigeixen que les creï d'una sola vegada."

Butler: L'analogia de la religió revelada.

"Així doncs, per acabar, que ningú no es basi en un concepte imperfecte de la sobrietat o una moderació mal aplicada per dir o mantenir que hom pot investigar massa o ser massa entès en el llibre de la paraula de Déu, o el llibres de les obres de Déu; divinitat o filosofia; al contrari, que hom s'esforci per progressar i millorar en ambdós camps."

Bacon: L'aprenentatge del coneixement

Down, Beckenham, Kent,
Primera edició, 24 de novembre del 1859.
Sisena edició, gener del 1872.

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L'ORIGEN DE LES ESPÈCIES MITJANÇANT SELECCIÓ NATURAL, O LA CONSERVACIÓ DE RACES AFAVORIDES EN LA LLUITA PER LA VIDA

DE CHARLES DARWIN, Llicenciat i Membre de la Royal Society & c.

SISENA EDICIÓ, AMB AFEGITS I CORRECCIONS.

(TRETZÈ MILER)

LONDRES:

JOHN MURRAY, ALBEMARLE STREET.

1873.

Reservat el dret de traducció.

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Pel mateix autor.

THE EXPRESSION OF THE EMOTIONS IN MAN AND ANIMALS.
Tenth Thousand. With Illustrations. Crown 8vo. 12s. Murray.

THE DESCENT OF MAN AND SELECTION IN RELATION TO SEX.
Eighth Thousand. 2 vols. 8vo. 24s. Murray.

THE VARIATION OF ANIMALS AND PLANTS UNDER DOMESTICATION.
Third Thousand. Illustrations. 2 vols. 8vo. 28s. Murray.

A NATURALIST'S VOYAGE ROUND THE WORLD; or,
A Journal of Researches into the Natural History and Geology of the Countries visited
Eleventh Thousand. Post 8vo. 9s.Murray.

THE VARIOUS CONTRIVANCES BY WHICH BRITISH AND FOREIGN ORCHIDS ARE FERTILISED BY INSECTS; and the
Good Effects of Crossing. Woodcuts. Post 8vo. 9s.Murray.

THE STRUCTURE AND DISTRIBUTION OF CORAL REEFS.
Smith., Elder, & Co.

GEOLOGICAL OBSERVATIONS ON VOLCANIC ISLANDS.
Smith., Elder, & Co.

GEOLOGICAL OBSERVATIONS ON SOUTH AMERICA.
Smith., Elder, & Co.

A MONOGRAPH OF THE CIRRIPEDIA.
Illustrations. 2 vols. 8vo.Ray Society. Hardwicke.

THE MOVEMENTS AND HABITS OF CLIMBING PLANTS.
Woodcuts.Williams & Norgate.

FACTS AND ARGUMENTS FOR DARWIN. By Fritz Müller.
From the German, with Addtions by the Author.
Translated by W.S. Dallas, F.L.S. Woodcuts. Post 8vo. 6s. Illustrations. 2 vols. 8vo.Murray.

LONDON: PRINTED BY WILLIAM CLOWES AND SONS, STAMFORD STREET
AND CHARING CROSS.

CONTINGUTS.

Afegits i correccions a la sisena edició	Pàg. 11‑12
Esbós històric	13‑21
Introducció	23‑26
Capítol I Variacions en Domesticitat
Causes de la variabilitat — Efectes dels hàbits i de l'ús i desús de parts del cos — Variació correlativa — Herència — Trets de les varietats domèstiques — Dificultat de distingir entre varietats i espècies — Origen de les varietats domèstiques a partir d'una o més espècies — Races del colom domèstic: diferències i origen — Principis de la selecció seguits des de l'antigor, i els seus efectes — Selecció metòdica i involuntària — Origen desconegut de les varietats domèstiques — Circumstàncies favorables al poder de selecció de l'home	27‑54
Capítol II Variacions a la natura
Variabilitat — Diferències individuals — Espècies dubtoses — Les espècies amb una àmplia àrea de distribució, molt difoses i comuns són les que més varien — Les espècies de grans gèneres d'un territori varien més sovint que les de gèneres menors — Moltes de les espècies incloses dins els grans gèneres s'assemblen a les varietats en que estan molt relacionades les unes amb les altres, encara que de manera desigual, i en que tenen àrees de distribució limitades	55‑69
Capítol III La lluita per la vida
La seva relació amb la selecció natural — El terme, utilitzat en un sentit ampli — Augment geomètric — Augment ràpid dels animals i plantes naturalitzats — Naturalesa dels controls en la limitació de les poblacions — Competition 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 between species of the same genus — The relation of organism to organism the most important of all relations	70‑83

Capítol IV. Natural Selection; or the Survival of the Fittest.
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 intercrosses between individuals of the same species — Circumstances favourable and unfavourable to the results of Natural Selection, namely, intercrossing, isolation, number of individuals — Slow action — Extinction caused by Natural Selection — Divergence of Character, 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 — Convergence of character — Indefinite multiplication of species — Summary	62-105
Capítol V. Laws of Variation.
Effects of changed conditions — Use and disuse, combined with natural selection; organs of flight and of vision — Acclimatisation — Correlated variation — 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	106-132
Capítol VI. Difficulties of the Theory.
Difficulties of the theory of descent with modification — 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 — Modes of transition — Cases of difficulty — Natura non fecit 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 df Natural Selection	133-167

Capítol VII. Miscellaneous Objections to the Theory of Natural Selection.
Longevity — Modifications not necessarily simultaneous — Modifications apparently of no direct service — Progressive development— Characters of small functional importance, the most constant — Supposed incompetence of natural selection to account for the incipient stages of useful structures — Causes which interfere with the acquisition through natural selection of useful structures — Gradations of structure with changed functions — Widely different organs in members of the same class, developed from one and the same source — Reasons for disbelieving in great and abrupt modifications	168-204
Capítol VIII. 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, molothrus, ostrich, and parasitic bees — Slave- making ants — Hive-bee, it's cell-making instinct — Changes of instinct and structure not necessarily simultaneous — Difficulties of the theory of the Natural Selection of instincts — Neuter or esterile insects — Summary	205-234
Capítol IX. Hybridism.
Distinction between the sterility of first crosses and of hybrids — Sterility various in degree, not universal, affected by close interbreeding, removed by domestication — Laws governing the sterility of hybrids — Sterility not a special endowment, but incidental on other differences, not accumulated by natural selection — Causes of the sterility of first crosses and of hybrids — Parallelism between the effects of changed conditions of life and of crossing — Dimorphism and trimorphism — Fertility of varieties when crossed and of their mongrel offspring not universal — Hybrids and mongrels compared independently of their fertility — Summary	234-263

Capítol X. 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 lapse of time, as inferred from the rate of denudation and of deposition — On the lapse of time as estimated by years — On the poorness of our palæontological collections — On the intermittence of geological formations — On the denudation of granitic areas — 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 — Antiquity of the habitable earth	264-289
Capítol XI. 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 appearance 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	290-315
Capítol XII. Geographical Distribution.
Present distribution cannot be accounted for by differences in physical conditions — Importance of barriers — Affinity of the productions of the same continent — Centres of creation — Means of dispersal, by changes of climate and of the level of the land, and by occasional means — Dispersal during the Glacial period — Alternate Glacial periods in the north and south	316-342
Capítol XIII. Geographical Distribution—continued.
Distribution of fresh-water productions — On the inhabitants of oceanic islands — Absence of Batrachians and of terrestrial Mammals — On the relation of the inhabitants of islands to those of the nearest mainland — On colonization from the nearest source with subsequent modification — Summary of the last and present chapter	343-362

Capítol XIV. 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 separates 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	363-403
Capítol XV. Recapitulation and Conclusion.
Recapitulation of the objections to 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	404-429
Glossary of Scientific Terms	430
Index	443