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Numerous small corrections have been made in the last and present editions on various subjects, according as the evidence has become somewhat stronger or weaker. The more important corrections and some additions in the present volume are tabulated on the following page, for the convenience of those interested in the subject, and who possess the fifth edition. The second edition was little more than a reprint of the first. The third edition was largely corrected and added to, and the fourth and fifth still more largely. As copies of the present work will be sent abroad, it may be of use if I specify the state of the foreign editions. The third French and second German editions were from the third English, with some few of the additions given in the fourth edition. A new fourth French edition has been translated by Colonel Moulinie"; of which the first half is from the fifth English, and the latter half from the present edition. A third German edition, under the superintendence of Professor Victor Carus, was from the fourth English edition; a fifth is now preparing by the same author from the present volume. The second American edition was from the English second, with a few of the additions given in the third; and a third American edition has been printed from the fifth English edition. The Italian is from the third, the Dutch and three Russian editions from the second English edition, and the Swedish from the fifth English edition.

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Influence of fortuitous destruction on natural selection.

On the convergence of specific forms.

Account of the Ground-Woodpecker of La Plata modified.

On the modification of the eye.

Transitions through the acceleration or retardation of the period of reproduction.

The account of the electric organ of fishes added to.

Analogical resemblance between the eyes of Cephalopoda and Vertebrates.

Claparede on the analogical resemblance of the hairclaspers of the Aearidai.

The probable use of the rattle to the Rattle-snake.

Helmholtz on the imperfection of the human eye.

The first part of this new chapter consists of portions, in a much modified state, taken from chap. iv. of the former editions. The latter and larger part is new, and relates chiefly to the supposed incompetency of natural selection to account for the incipient stages of useful structures. There is also a discussion on the causes which prevent in many cases the acquisition through natural selection of useful structures. Lastly, reasons are given for disbelieving in great and sudden modifications. Gradations of character, often accompanied by changes of function, are likewise here incidentally considered.

The statement with respect to young cuckoo ejecting their foster-brothers confirmed.

On the cuckoo-like habits of the Molothrus.

On fertile hybrid moths.

The discussion on the fertility of hybrids not having

been acquired through natural selection condensed

and modified.

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Chief Additions and Correcttnne.

On the causes of sterility of hybrids, added to and

Pyrgoma found in the chalk.
Extinct forms serving to connect existing groups.
On earth adhering to the feet of migratory birds.
On the wide geographical range of a species of

Galaxias, a fresh-water fish.
Discussion on analogical resemblances, enlarged and

Homological structure of the feet of certain mar-
supial animals.
On serial homologies, corrected.
Mr. E. Ray Lankester on morphology.
On the asexual reproduction of Chironomus.
On the origin of rudimentary parts, corrected.
Recapitulation on the sterility of hybrids, corrected.
Recapitulation on the absence of fossils beneath the

Cambrian system, corrected.
Natural selection not the exclusive agency in the

modification of species, as always maintained in

this work. The belief in the separate creation of species generally

held by naturalists, until a recent period.

"But with regard to the material world, we can at least go so far as this—we can perceive that events are brought about not by insulated interpositioDs of Divine power, exerted in each particular case, but by the establishment of general laws."

Whewei.l: Bridgewater Treatise.

"The only distinct meaning of the word 'natural' is stated, fixed, or settled; since what is natural as much requires and presupposes an intelligent agent to render it so, i.e., to effect it continually or at stated times, as what is supernatural or miraculous does to effect it for once."

Botlkb: Analogy ,f Revealed Religion.

"To conclude, therefore, let no man out of a weak conceit of sobriety, or an ill-applied moderation, think or maintain, that a man can search too far or be too well studied in the book of God's word, or in the book of God's works; divinity or philosophy; but rather let men endeavour an endless progress or proficiency in both."

Bacon: Advancement of Learning.

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I Will here give a brief sketch of the progress of opinion on the Origin of Species. Until recently the great majority of naturalists believed that species were immutable productions, and had been separately created. This view has been ably maintained by many authors. Some few naturalists, on the other hand, have believed that species undergo modification, and that the existing forms of life are the descendants by true generation of pre-existing forms. Passing over allusions to the subject in the classical writers,* the first author who in

* Aristotle, in his ' Physic® Auscultationes' (lib. 2, cap. 8, s. 2), after remarking that rain does not fall in order to make the corn grow, any more than it falls to spoil the farmer's corn when threshed out of doors, applies the same argument to organisation; and adds (as translated by Mr. Clair Grece, who first pointed out the passage to me), " So what hinders the different parts [of the body] from having this merely accidental relation in nature? as the teeth, for example, grow by necessity, the front ones sharp, adapted for dividing, and the grinders flat, and serviceable for masticating the food; since they were not made for the sake of this, but it was the result of accident. And in like manner as to the other parts in which there appears to exist an adaptation to an end. Wheresoever, therefore, all things together (that is all the parts of one whole) happened like as if they were made for the sake of something, these were preserved, having been appropriately constituted

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