Page:Origin of Species 1872.djvu/12

 {| border=1 align=center 100 158 220 225 230 231 233  234  248 248 255           268  270 307 319  326 377 402 440 463  505 516  518 520 521 541 547 552  568  572 68 101 142 145 149  150 151  153  162 163 168           214  215 240 248  252 284 301 328 343  373 382  384 385 387 401 405 409  421  424 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. Claparède on the analogical resemblance of the hair-claspers of the Acaridæ. 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 dis- believing 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. 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 Cam- brian system, corrected. Natural selection not the exclusive agency in the modi- fication of species, as always maintained in this work. The belief in the separate creation of species generally held by naturalists, until a recent period.
 * style="text-align:center"|Fifth Edition.||style="text-align:center"|Sixth Edition.||style="text-align:center"|Chief Additions and Corrections.
 * valign=top|Page
 * valign=top|Page
 * valign=top|Page
 * valign=top| Influence of fortuitous destruction on natural selection.
 * }