CHAPTER XIV.

MUTUAL AFFINITIES OF ORGANIC BEINGS: MORPHOLOGY:
EMBRYOLOGY: RUDIMENTARY ORGANS.

- Rules

-

-

CLASSIFICATION, groups subordinate to groups - Natural system
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

Page 363-403

-

-

-

--

CHAPTER 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 -
cluding remarks

-

GLOSSARY OF SCIENTIFIC TERMS

INDEX

-

Con-
404-429

430

443

ADDITIONS AND CORRECTIONS

TO THE SIXTH EDITION.

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 Moulinié; 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.

234

248 162 163

248

255

168

268

214

270 215 307 240 319 248

326 252 377 284 402 301 440 328 463 343

505 373

516 382

572

153 Claparède on the analogical resemblance of the hair-claspers

of the Acarida.

Chief Additions and Corrections.

424

Influence of

uitous 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 Cephalopods and Vertebrates.

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 cuckoos 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 ac-
quired through natural selection condensed and modified.
On the causes of sterility of hybrids, added to and corrected.
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 modified. Homological structure of the feet of certain marsupial animals.

518

384

520

385

521 387

541 401
547 405

On the origin of rudimentary parts, corrected.
Recapitulation on the sterility of hybrids, corrected.

552 409 Recapitulation on the absence of fossils beneath the Cam

568

421

On serial homologies, corrected.

Mr. E. Ray Lankester on morphology.

On the asexual reproduction of Chironomus.

brian 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.

AN HISTORICAL SKETCH

OF THE PROGRESS OF OPINION ON THE ORIGIN OF SPECIES,

PREVIOUSLY TO THE PUBLICATION OF THE FIRST EDITION
OF THIS WORK.

I WILL here a 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 modern times has treated it in a scientific spirit was Buffon. But as his opinions fluctuated greatly at different periods, and as he does not enter on the causes or means of the transformation of species, I need not here enter on details.

Lamarck was the first man whose conclusions on the subject excited much attention. This justly-celebrated naturalist first published his views in 1801; he much enlarged them in 1809 in his 'Philosophie Zoologique,' and subsequently, in 1815, in the Introduction to his 'Hist. Nat. des Animaux sans Vertébres.' In these

6

* Aristotle, in his Physicæ 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 by an internal spontaneity; and whatsoever things were not thus constituted, perished, and still perish." We here see the principle of natural selection shadowed forth, but how little Aristotle fully comprehended the principle, is shown by his ren arka on the formation of the teeth.