as to sea-urchins; as to certain processes of metamorphosis; as to the mammary gland; as to certain ape characters; 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 simultaneous modification of many individuals.—Summary and conclusion ... Page [23]
CHAPTER III.
THE CO-EXISTENCE OF CLOSELY SIMILAR STRUCTURES OF DIVERSE ORIGIN.
Chances against concordant variations.—Examples of discordant ones.—Concordant variations not unlikely on a non-Darwinian evolutionary hypothesis.—Placental and implacental mammals.—Birds and reptiles.—Independent origins of similar sense organs.—The ear.—The eye.—Other coincidences.—Causes besides Natural Selection produce concordant variations in certain geographical regions.—Causes besides Natural Selection produce concordant variations in certain zoological and botanical groups.—There are homologous parts not genetically related.—Harmony in respect of the organic and inorganic worlds.—Summary and conclusion ... Page [63]
CHAPTER IV.
MINUTE AND GRADUAL MODIFICATIONS.
There are difficulties as to minute modifications, even if not fortuitous.—Examples of sudden and considerable modifications of different kinds.—Professor Owen's view.—Mr. Wallace.—Professor Huxley.—Objections to sudden changes.—Labyrinthodont.—Potto.—Cetacea.—As to origin of bird's wing.—Tendrils of climbing plants.—Animals once supposed to be connecting links.—Early specialization of structure.—Macrauchenia.—Glyptodon.—Sabre-toothed tiger.—Conclusion ... Page [97]
CHAPTER V.
AS TO SPECIFIC STABILITY.