viii CONTENTS. 



to sea-urehius ; as to oertaiu processes ot" metainoiphosis ; as to the 

 inainniary glaml ; as to certain ape charaotcrs ; as to the rattlesnake 

 and cobra ; as to the process of formation of the eye and ear ; as to 

 the fully developed condition of the eye and ear ; as to the voice ; as 

 to shell-fish : as to orchids ; as to ants, — The necessity for the simulta- 

 neous iiiodilitatiun of many individuals. — Summary and conclusion. 



Piuje 26 



CHAl'TKII III. 



THE COKXISTESCE OF CLOSELY SIMILAR STRUCTURES OF 



DIVERSE ORIGIN. 



Chances against concordant variations — Examples of discordant ones. — 

 I'lincordant variations not unlikely on a nun-Darwinian evolutionary 

 li\ I'Otlu'sis. — Placental and implaceutal mammals. — Birds and reptiles. 

 — Independent origins of similar sense organs. — The ear. — The eye. — 

 Othtr coincidences. — Causes besides "Natural Selection" produce con- 

 cordant variations, in certain geograjdiical regions. — Causes besides 

 " Natural Selection" produce concordant variations, in certain zoological 

 and botanical groups. — There are homologous parts not genetically 

 relatctl. — Harmony in respect of the organic and inorganic worlds. — 

 Summary and (Conclusion Pa<ie 71 



CHAI'TKU IV. 



MIXUTE .IND GRADUAL MODIFICATIONS. 



There are difficulties as to minute modifications, even if not fortuitous. — 

 Exami>les of sudden and considerable modifications of dilFi-rent kinds. — 

 Professor Owen's view. — Mr. Wallace. — Profes.sor Huxley. — Objections 

 to sudden changes. — Labyrinthodont. — Potto. — Cetacea. — As to origin 

 of bird's wing. — Tendrils of climbing plants. — Animals once suppo.sed 

 to be connecting links. — Early .specialization of structure.— Macrau- 

 chenia,— Glyptodon. — Sabre-toothed tiger. — Conclusion Putir 109 



