F877.2    Book:     Darwin, C. R. 1868. The variation of animals and plants under domestication. London: John Murray. 1st ed., first issue. vol. 2.   Text   Image   PDF

be either artificial,—that is, founded on any arbitrary character,—or natural. With varieties a natural classification is certainly founded, and with species is apparently founded, on community of descent, together with the amount of modification which the forms have undergone. The characters by which domestic varieties differ from each other are more [page] 41

F877.2    Book:     Darwin, C. R. 1868. The variation of animals and plants under domestication. London: John Murray. 1st ed., first issue. vol. 2.   Text   Image   PDF

fail to retain their primordial state,—are the same with the parts which differ in the natural species of the same genus. As, on the theory of descent with modification, the species of the same genus have been modified since they branched off from a common progenitor, it follows that the characters by which they differ from each other have varied whilst other parts of the organisation have remained unchanged; and it might be argued that [page] 6

F877.1    Book:     Darwin, C. R. 1868. The variation of animals and plants under domestication. London: John Murray. 1st ed., first issue. vol. 1.   Text   Image   PDF

sides with equal ease; the pupil was small and oval, or rather a parallelogram with the ends cut off, and lying transversely across the ball. A new and strange breed might probably have been formed by careful breeding and selection from this animal. I have often speculated on the probable causes through which each separate district in Great Britain came to possess in former times its own peculiar breed of cattle; and the question is, perhaps, even more perplexing in the case of Southern Africa

F878.1    Book:     Darwin, C. R. 1868. The variation of animals and plants under domestication. London: John Murray. 1st ed., second issue. vol. 1.   Text   Image   PDF

sides with equal ease; the pupil was small and oval, or rather a parallelogram with the ends cut off, and lying transversely across the ball. A new and strange breed might probably have been formed by careful breeding and selection from this animal. I have often speculated on the probable causes through which each separate district in Great Britain came to possess in former times its own peculiar breed of cattle; and the question is, perhaps, even more perplexing in the case of Southern Africa

F877.2    Book:     Darwin, C. R. 1868. The variation of animals and plants under domestication. London: John Murray. 1st ed., first issue. vol. 2.   Text   Image   PDF

previously remarked, than the retention during many ages of rudimentary organs, or even only of a tendency to the production of a rudiment; but there is no reason to suppose that all dormant gemmules would be transmitted and propagated for ever. Excessively minute and numerous as they are believed to be, an infinite number derived, during a long course of modification and descent, from each cell of each progenitor, could not be supported or nourished by the organism. On the other hand, it does

F879.1    Book:     Darwin, C. R. [1868]. The variation of animals and plants under domestication. With a preface by Asa Gray. New York: Orange Judd and Co. vol. 1.   Text   Image   PDF

were specifically different, though most closely related to each other. The archipelago. With its innumerable craters and bare streams of lava, appeared to be of recent origin; and thus I fancied myself brought near to the very act of creation. I often asked myself how these many peculiar animals and plants had been produced: the simplest answer seemed to be that the inhabitants of the several islands had descended from each other, undergoing modification in the course of their descent; and that

F879.1    Book:     Darwin, C. R. [1868]. The variation of animals and plants under domestication. With a preface by Asa Gray. New York: Orange Judd and Co. vol. 1.   Text   Image   PDF

Product of variation, we can understand why they have not become feral, for the great amount of modification which they have undergone shows how long and how thoroughly they have been domesticated; and this would unfit them for a wild life. Fourthly. If it be assumed that the characteristic differences between the various domestic races are due to descent from several aboriginal species, we must conclude that man chose for domestication in ancient times, either intentionally or by chance, a

F878.1    Book:     Darwin, C. R. 1868. The variation of animals and plants under domestication. London: John Murray. 1st ed., second issue. vol. 1.   Text   Image   PDF

parallel manner, in the seed being downy or glabrous, and in colour, and in the florets being barbed or not barbed, c. Those who believe that all the kinds are descended from a single wild species may account for this parallel variation by the inheritance of a similar constitution, and a consequent tendency to vary in the same manner; and those who believe in the general theory of descent with modification may extend this view to the several species of wheat, if such ever existed in a state of

F878.1    Book:     Darwin, C. R. 1868. The variation of animals and plants under domestication. London: John Murray. 1st ed., second issue. vol. 1.   Text   Image   PDF

racters alone. This fact is explicable through the doctrine of natural selection; for each successive modification of structure in each natural species is preserved, solely because it is of service; and such modifications when largely accumulated imply a great change in the habits of life, and this will almost certainly lead to other changes of structure throughout the whole organisation. On the other hand, if the several races of the pigeon have been produced by man through selection and

F387    Book:     Darwin, C. R. 1869. On the origin of species by means of natural selection, or the preservation of favoured races in the struggle for life. London: John Murray. 5th ed. Tenth thousand.   Text   Image   PDF

other such cases, is intelligible, for generally within the same country, the existing and the extinct will be closely allied by descent. Looking to geographical distribution, if we admit that there has been during the long course of ages much migration from one part of the world to another, owing to former climatal and geographical changes and to the many occasional and unknown means of dispersal, then we can understand, on the theory of descent with modification, most of the great leading facts

F387    Book:     Darwin, C. R. 1869. On the origin of species by means of natural selection, or the preservation of favoured races in the struggle for life. London: John Murray. 5th ed. Tenth thousand.   Text   Image   PDF

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

F387    Book:     Darwin, C. R. 1869. On the origin of species by means of natural selection, or the preservation of favoured races in the struggle for life. London: John Murray. 5th ed. Tenth thousand.   Text   Image   PDF

this element of descent, the one certainly known cause of similarity in organic beings, we shall understand what is meant by the Natural System: it is genealogical in its attempted arrangement, with the grades of acquired difference marked by the terms, varieties, species, genera, families, orders, and classes. On this same view of descent with modification, all the great facts in Morphology become intelligible, whether we look to the same pattern displayed by the different species of the same

F387    Book:     Darwin, C. R. 1869. On the origin of species by means of natural selection, or the preservation of favoured races in the struggle for life. London: John Murray. 5th ed. Tenth thousand.   Text   Image   PDF

pal ontologists is frequently the case. Thus, on the theory of descent with modification, the main facts with respect to the mutual affinities of the extinct forms of life to each other and to living forms, are explained in a satisfactory manner. And they are wholly inexplicable on any other view. On this same theory, it is evident that the fauna of [page] 40

F387    Book:     Darwin, C. R. 1869. On the origin of species by means of natural selection, or the preservation of favoured races in the struggle for life. London: John Murray. 5th ed. Tenth thousand.   Text   Image   PDF

inexplicable on the theory of independent acts of creation. The existence of closely allied or representative species in any two areas, implies, on the theory of descent with modification, that the same parent-forms formerly inhabited both areas; and we almost invariably find that wherever many closely allied species inhabit two [page] 56

F387    Book:     Darwin, C. R. 1869. On the origin of species by means of natural selection, or the preservation of favoured races in the struggle for life. London: John Murray. 5th ed. Tenth thousand.   Text   Image   PDF

less and more improved states of a species, as well as the original parent-species itself, will generally tend to become extinct. So it probably will be with many whole collateral lines of descent, which will be conquered by later and improved lines of descent. If, however, the modified offspring of a species get into some distinct country, or become quickly adapted to some quite new station, in which offspring and progenitor do not come into competition, both may continue to exist. If, then

F387    Book:     Darwin, C. R. 1869. On the origin of species by means of natural selection, or the preservation of favoured races in the struggle for life. London: John Murray. 5th ed. Tenth thousand.   Text   Image   PDF

covered having affinities directed towards very distinct groups. Yet if we compare the older Reptiles and Batrachians, the older Fish, the older Cephalopods, and the eocene Mammals, with the more recent members of the same classes, we must admit that there is truth in the remark. Let us see how far these several facts and inferences accord with the theory of descent with modification. As the subject is somewhat complex, I must request the reader to turn to the diagram in the fourth chapter. We

F387    Book:     Darwin, C. R. 1869. On the origin of species by means of natural selection, or the preservation of favoured races in the struggle for life. London: John Murray. 5th ed. Tenth thousand.   Text   Image   PDF

deceive myself, on the view that the Natural System is founded on descent with modification; that the characters which naturalists consider as showing true affinity between any two or more species, are those which have been inherited from a common parent, all true classification being genealogical; that community of descent is the hidden bond which naturalists have been unconsciously seeking, and not some unknown plan of creation, or the enunciation of general propositions, and the mere putting

F387    Book:     Darwin, C. R. 1869. On the origin of species by means of natural selection, or the preservation of favoured races in the struggle for life. London: John Murray. 5th ed. Tenth thousand.   Text   Image   PDF

encountered on the theory of descent with modification are serious enough. All the individuals of the same species, and all the species of the same genus, or even higher group, must have descended from common parents; and therefore, in however distant and isolated parts of the world they may now be found, they must in the course of successive generations have travelled from some one point to all the others. We are often wholly unable even to conjecture how this could have been effected. Yet

F387    Book:     Darwin, C. R. 1869. On the origin of species by means of natural selection, or the preservation of favoured races in the struggle for life. London: John Murray. 5th ed. Tenth thousand.   Text   Image   PDF

presented a widely different aspect; and that the older continents, formed of formations older than any known to us, exist now only as remnants in a metamorphosed condition, or lie still buried under the ocean. Passing from these difficulties, the other great leading facts in pal ontology seem to me simply to follow on the theory of descent with modification through natural selection. We can thus understand how it is that new species come in slowly and successively; how species of different classes do

F387    Book:     Darwin, C. R. 1869. On the origin of species by means of natural selection, or the preservation of favoured races in the struggle for life. London: John Murray. 5th ed. Tenth thousand.   Text   Image   PDF

, because allied in blood and alike in some other respects. With species in a state of nature, every naturalist has in fact brought descent into his classification; for he includes in his lowest grade, that of the species, the two sexes; and how enormously these sometimes differ in the most important characters, is known to every naturalist: scarcely a single fact can be predicated in common of the adult males and hermaphrodites of certain cirripedes, and yet no one dreams of separating them. As

F387    Book:     Darwin, C. R. 1869. On the origin of species by means of natural selection, or the preservation of favoured races in the struggle for life. London: John Murray. 5th ed. Tenth thousand.   Text   Image   PDF

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 .. .. .. .. Page 165-206 CHAPTER VI. DIFFICULTIES OF THE THEORY. Difficulties of the theory of descent with modification Transitions Absence or rarity of transitional

F387    Book:     Darwin, C. R. 1869. On the origin of species by means of natural selection, or the preservation of favoured races in the struggle for life. London: John Murray. 5th ed. Tenth thousand.   Text   Image   PDF

physiology lends any countenance; their existence would seem to show that the amount of modification which living beings have undergone during geological time is but very small in relation to the whole series of changes which they have suffered. In December, 1859, Dr. Hooker published his 'Introduction to the Australian Flora.' In the first part of this great work he admits the truth of the descent and modification of species, and supports this doctrine by many original observations. The first edition of

F387    Book:     Darwin, C. R. 1869. On the origin of species by means of natural selection, or the preservation of favoured races in the struggle for life. London: John Murray. 5th ed. Tenth thousand.   Text   Image   PDF

He who will go thus far, ought not to hesitate to go one step further, if he finds on finishing this volume that large bodies of facts, otherwise inexplicable, can be explained by the theory of descent with modification; he ought to admit that a structure even as perfect as an eagles eye might be formed by natural selection, although in this case he does not know the transitional states. It has been objected that in order to modify the eye and still preserve it as a perfect instrument, many

F387    Book:     Darwin, C. R. 1869. On the origin of species by means of natural selection, or the preservation of favoured races in the struggle for life. London: John Murray. 5th ed. Tenth thousand.   Text   Image   PDF

something more is included in our classification than mere resemblance. I believe that something more is included, and that propinquity of descent the only known cause of the similarity of organic beings is the bond, hidden as it is by various degrees of modification, which is partially revealed to us by our classifications. Let us now consider the rules followed in classification, and the difficulties which are encountered, on the view that classification either gives some unknown plan of

F387    Book:     Darwin, C. R. 1869. On the origin of species by means of natural selection, or the preservation of favoured races in the struggle for life. London: John Murray. 5th ed. Tenth thousand.   Text   Image   PDF

succession of the same types within the same areas Summary of preceding and present chapter. LET us now see whether the several facts and laws relating to the geological succession of organic beings, better accord with the common view of the immutability of species, or with that of their slow and gradual modification, through descent and natural selection. New species have appeared very slowly, one after another, both on the land and in the waters. Lyell has shown that it is hardly possible to resist