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

mammals to Africa than it is at the present time. Analogous facts could be given in relation to the distribution of marine animals. On the theory of descent with modification, the great law of the long enduring, but not immutable, succession of the same types within the same areas, is at once explained; for the inhabitants of each quarter of the world will obviously tend to leave in that quarter, during the next succeeding period of time, closely allied though in some degree modified descendants

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

scheme of modification, by means of rudimentary organs, embryological and homologous structures, but we wilfully will not understand the scheme. I have now recapitulated the facts and considerations which have thoroughly convinced me that species have been modified, during a long course of descent, chiefly through the natural selection of numerous successive, slight, favourable variations. I cannot believe that a false theory would explain, as it seems to me that the theory of natural selection

F937.1    Book:     Darwin, C. R. 1871. The descent of man, and selection in relation to sex. London: John Murray. vol. 1.   Text   Image   PDF

almost certain that the third line would still retain through inheritance numerous small points of resemblance with the other two lines. Here then would occur the difficulty, at present insoluble, how much weight we ought to assign in our classifications to strongly-marked differences in some few points, that is to the amount of modification undergone; and how much to close resemblance in numerous unimportant points, as indicating the lines of descent or genealogy. The former alternative is the most

F937.1    Book:     Darwin, C. R. 1871. The descent of man, and selection in relation to sex. London: John Murray. vol. 1.   Text   Image   PDF

, separate from the co-descendants of any other form; but if the parent-forms are related, so will be their descendants, and the two groups together will form a larger group. The amount of difference between the several groups that is the amount of modification which each has undergone will be expressed by such terms as genera, families, orders, and classes. As we have no record of the lines of descent, these lines can be discovered only by observing the degrees of resemblance between the beings

A576    Pamphlet:     Wright, Chauncey. 1871. Darwinism: Being an examination of Mr. St. George Mivart's 'Genesis of species,' [Reprinted from the 'North American Review,' July 1871, with additions]. London: John Murray. 46pp.   Text   Image

the theological critics of the theory, but to its scientific advocates; although, from the neutral ground of experimental science, descent with modification is the most pertinent and least exceptionable name. While the general doctrine of evolution has thus been successfully redeemed from theological condemnation, this is not yet true of the subordinate hypothesis of Natural Selection, to the partial success of which this change of opinion is, in great measure, due. It is, at first sight a

F391    Book:     Darwin, C. R. 1872. The origin of species by means of natural selection, or the preservation of favoured races in the struggle for life. London: John Murray. 6th ed.; with additions and corrections. Eleventh thousand.   Text   Image   PDF

CHAPTER 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

F391    Book:     Darwin, C. R. 1872. The origin of species by means of natural selection, or the preservation of favoured races in the struggle for life. London: John Murray. 6th ed.; with additions and corrections. Eleventh thousand.   Text   Image   PDF

, undergoing modification during their migration, from some one area. If, when most of the species inhabiting one region are different from those of another region, though closely allied to them, it can be shown that migration from the one region to the other has probably occurred at some former period, our general view will be much strengthened; for the explanation is obvious on the principle of descent with modification. A volcanic island, for instance, upheaved and formed at the distance of a few

F391    Book:     Darwin, C. R. 1872. The origin of species by means of natural selection, or the preservation of favoured races in the struggle for life. London: John Murray. 6th ed.; with additions and corrections. Eleventh thousand.   Text   Image   PDF

, within known geological periods, undergone much modification, should in the older formations make some slight approach to each other; so that the older members should differ less from each other in some of their characters than do the existing members of the same groups; and this by the concurrent evidence of our best palæontologists 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

F391    Book:     Darwin, C. R. 1872. The origin of species by means of natural selection, or the preservation of favoured races in the struggle for life. London: John Murray. 6th ed.; with additions and corrections. Eleventh thousand.   Text   Image   PDF

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, most of the great facts in Morphology become intelligible,—whether we look to the same pattern displayed by the different species of the same class in their homologous organs, to whatever purpose applied; or to the serial and lateral homologies in each individual animal and plant. On the principle

F391    Book:     Darwin, C. R. 1872. The origin of species by means of natural selection, or the preservation of favoured races in the struggle for life. London: John Murray. 6th ed.; with additions and corrections. Eleventh thousand.   Text   Image   PDF

the descent and modification of species, and supports this doctrine by many original observations. The first edition of this work was published on November 24th, 1859, and the second edition on January 7th, 1860. [page xxii

F391    Book:     Darwin, C. R. 1872. The origin of species by means of natural selection, or the preservation of favoured races in the struggle for life. London: John Murray. 6th ed.; with additions and corrections. Eleventh thousand.   Text   Image   PDF

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 may suppose

F391    Book:     Darwin, C. R. 1872. The origin of species by means of natural selection, or the preservation of favoured races in the struggle for life. London: John Murray. 6th ed.; with additions and corrections. Eleventh thousand.   Text   Image   PDF

CHAPTER 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 facit saltum — Organs of small importance — Organs not in all cases absolutely perfect — The law of Unity of Type and of the

F391    Book:     Darwin, C. R. 1872. The origin of species by means of natural selection, or the preservation of favoured races in the struggle for life. London: John Murray. 6th ed.; with additions and corrections. Eleventh thousand.   Text   Image   PDF

. 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 facit saltum — Organs of small importance — Organs not in all cases absolutely perfect — The law of Unity of Type and of the Conditions of Existence

F391    Book:     Darwin, C. R. 1872. The origin of species by means of natural selection, or the preservation of favoured races in the struggle for life. London: John Murray. 6th ed.; with additions and corrections. Eleventh thousand.   Text   Image   PDF

Lankester, who has drawn an important distinction between certain classes of cases which have all been equally ranked by naturalists as homologous. He proposes to call the structures which resemble each other in distinct animals, owing to their descent from a common progenitor with subsequent modification, homogenous; and the resemblances which cannot thus be accounted for, he proposes to call homoplastic. For instance, he believes that the hearts of birds and mammals are as a whole homogenous,—that is

F391    Book:     Darwin, C. R. 1872. The origin of species by means of natural selection, or the preservation of favoured races in the struggle for life. London: John Murray. 6th ed.; with additions and corrections. Eleventh thousand.   Text   Image   PDF

CHAPTER 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

F391    Book:     Darwin, C. R. 1872. The origin of species by means of natural selection, or the preservation of favoured races in the struggle for life. London: John Murray. 6th ed.; with additions and corrections. Eleventh thousand.   Text   Image   PDF

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 areas, some identical species are still common to both. Wherever many closely allied yet distinct species occur, doubtful forms and varieties belonging to the same groups likewise occur. It is a rule of high generality that the inhabitants of each area are related to

F391    Book:     Darwin, C. R. 1872. The origin of species by means of natural selection, or the preservation of favoured races in the struggle for life. London: John Murray. 6th ed.; with additions and corrections. Eleventh thousand.   Text   Image   PDF

('Bulletins de l'Acad. Roy. Bruxelles, tom. xiii. p. 581), his opinion that it is more probable that new species have been produced by descent with modification than that they have been separately created: the author first promulgated this opinion in 1831. Professor Owen, in 1849 ('Nature of Limbs,' p. 86), wrote as follows:— The archetypal idea was manifested in the flesh under diverse such modifications, upon this planet, long prior to the existence of those animal species that actually exemplify

F391    Book:     Darwin, C. R. 1872. The origin of species by means of natural selection, or the preservation of favoured races in the struggle for life. London: John Murray. 6th ed.; with additions and corrections. Eleventh thousand.   Text   Image   PDF

The similar framework of bones in the hand of a man, wing of a bat, fin of a porpoise, and leg of the horse,—the same number of vertebræ forming the neck of the giraffe and of the elephant,—and innumerable other such facts, at once explain themselves on the theory of descent with slow and slight successive modifications. The similarity of pattern in the wing and in the leg of a bat, though used for such different purpose,—in the jaws and legs of a crab,—in the petals, stamens, and pistils of a

F391    Book:     Darwin, C. R. 1872. The origin of species by means of natural selection, or the preservation of favoured races in the struggle for life. London: John Murray. 6th ed.; with additions and corrections. Eleventh thousand.   Text   Image   PDF

distinct act of creation. The term variety is almost equally difficult to define; but here community of descent is almost universally implied, though it can rarely be proved. We have also what are called monstrosities; but they graduate into varieties. By a monstrosity I presume is meant some considerable deviation of structure, generally injurious, or not useful to the species. Some authors use the term variation in a technical sense, as implying a modification directly due to the physical conditions

F391    Book:     Darwin, C. R. 1872. The origin of species by means of natural selection, or the preservation of favoured races in the struggle for life. London: John Murray. 6th ed.; with additions and corrections. Eleventh thousand.   Text   Image   PDF

resemblance. I believe that this is the case, and that community of descent—the one known cause of close similarity in organic beings—is the bond, which though observed by various degrees of modification, 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 creation, or is simply a scheme for enunciating general propositions and of placing

F391    Book:     Darwin, C. R. 1872. The origin of species by means of natural selection, or the preservation of favoured races in the struggle for life. London: John Murray. 6th ed.; with additions and corrections. Eleventh thousand.   Text   Image   PDF

rudimentary nails on the fin of the manatee have been developed for this same purpose. On the view of descent with modification, the origin of rudimentary organs is comparatively simple; and we can understand to a large extent the laws governing their imperfect development. We have plenty of cases of rudimentary organs in our domestic productions,—as the stump of a tail in tailless breeds,—the vestige of an ear in earless breeds of sheep, the reappearance of minute dangling horns in hornless

F944    Book:     Darwin, C. R. 1874. The descent of man, and selection in relation to sex. London: John Murray. 2d ed.; tenth thousand.   Text   Image   PDF

, apart from the co-descendants of any other form; but if the parent-forms are related, so will be their descendants, and the two groups together will form a larger group. The amount of difference between the several groups that is the amount of modification which each has undergone is expressed by such terms as genera, families, orders, and classes. As we have no record of the lines of descent, the pedigree can be discovered only by observing the degrees of resemblance between the beings which are

F944    Book:     Darwin, C. R. 1874. The descent of man, and selection in relation to sex. London: John Murray. 2d ed.; tenth thousand.   Text   Image   PDF

unimportant points. The greater number of naturalists who have taken into consideration the whole structure of man, including his mental faculties, have followed Blumenbach and Cuvier, and have placed man in a separate Order, under the title of the Bimana, and therefore on an equality with the orders of the Quadrumana, Carnivora, c. Recently many of our best naturalists have recurred to the view first propounded by Linn us, so remarkable for his sagacity, and have placed man in the same Order with the

F880.1    Book:     Darwin, C. R. 1875. The variation of animals and plants under domestication. London: John Murray. 2d ed. vol. 1.   Text   Image   PDF

seems to have been unbroken or continuous. New species come in gradually one by one. Ancient and extinct forms of life are often intermediate in character, like the words of a dead language with respect to its several offshoots or living tongues. All these facts seemed to me to point to descent with modification as the means of production of new species. The innumerable past and present inhabitants of the world are connected together by the most singular and complex affinities, and can be classed

F880.1    Book:     Darwin, C. R. 1875. The variation of animals and plants under domestication. London: John Murray. 2d ed. vol. 1.   Text   Image   PDF

, birds, reptiles, and fish. It is the consideration and explanation of such facts as these which has convinced me that the theory of descent with modification by means of natural selection is in the main true. These facts have as yet received no explanation on the theory of independent Creation; they cannot be grouped together under one point of view, but each has to be considered as an ultimate fact. As the first origin of life on this earth, as well as the continued life of each individual, is at