Evolution is continuity, causal relation, gradual becoming—Increasing acceptance of this idea—First accepted for inorganic forms, mountains, continents and seas, rocks and soils, earth as a whole, heavenly bodies—Therefore acknowledged for all inorganics—Influence of geology in bringing about this change—Organic forms: acknowledged for individuals, true for classes, orders, families, genera—Races and varieties also formed gradually—Artificial species formed gradually—Examples of gradual changes in wild species—Hyatt’s researches—Other examples—Summing up of general evidence—Sufficient ground for induction—But evolution is not only inductively probable but certain, axiomatic—It is the law of causation applied to forms, and therefore a necessary truth 53 CHAPTER II. SPECIAL PROOFS OF EVOLUTION. Introductory. Special proofs necessary—Evolution, though certain, is not yet accepted by the popular mind—Different departments from which proofs are drawn 67 Origin of new organic forms; the old view briefly stated—Necessary to give a brief statement of theories—Old view—Permanency of specific types—Supernatural origin of species—Centers of creation—Explanation of facts of geographical distribution—Of geological distribution—Modification of extreme view—Variability, but within limits—Illustrated 68 The new view briefly stated—Indefinite variability of organic forms—Effect of environment on rigid forms—On plastic forms—Taxonomic groups represent degrees of kinship 72 Factors of evolution—(1) Physical environment—(2) Use and disuse of organs—(3) Natural selection—(4) Sexual selection—(5) Physiological selection—Its necessity shown—Its operation explained—Compared with natural selection—Cause of variation unknown—Explanation of this is the next great step in the theory of evolution 73 CHAPTER III. THE GRADES OF THE FACTORS OF EVOLUTION AND THE ORDER OF THEIR APPEARANCE. Factors of evolution restated; their grades and the order of their introduction shown—Lamarckian factors, first in order because they precede sexual reproduction—(1) Environment—(2) Use and disuse—With sexual reproduction selective factors introduced—(3) Natural selection—(4) Physiological selection—(5) Sexual selection—With man was introduced (6) the rational factor—In this process two striking stages—viz., the introduction of sex and the introduction of reason—Effect of each to hasten the steps of evolution—The last by far the greater change 81 Contrast between organic and human evolution—(1) The meaning of term fittest in each—(2) Destiny of the weak and helpless in each—(3) The nature of evolutionary transformation in each—(4) The law of strait and narrow way applied in each—(5) Human evolution is a different kind and on a higher plane 88 Application to some questions of the day. I. Neo-Darwinists, their position explained—Reasons for dissenting—(a) Lamarckian factors preceded all others—(b) Though now subordinate, they still underlie and condition all other factors—(c) Shown by comparison of phylogeny with ontogeny 92 II. Human progress not identical with organic evolution—Mistake of the materialists—But neither is it wholly different, as some suppose 96 III. Neo-Darwinism is fatal to hopes of human progress—Reason may use freely Lamarckian factors, but can not use natural selection in the same way as Nature does 97 CHAPTER IV. SPECIAL PROOFS FROM THE GENERAL LAWS OF ANIMAL STRUCTURE, OR COMPARISON IN THE TAXONOMIC SERIES. General Principles. Analogy and homology—Defined and illustrated by examples—Wings and limbs—Lungs, gradual formation of, traced in the Taxonomic series—Traced in the Ontogenic series—Examples of homology in plants: tuber, cactus-leaf, acacia-leaf—Definitions repeated and further explained—Common origin is the only explanation of homology 99 Primary divisions of the animal kingdom—True ground of such divisions is ability to trace homology—We take examples only from vertebrata and articulata—Compare to styles of architecture—To machines—To branching stem 107 CHAPTER V. PROOFS FROM HOMOLOGIES OF THE VERTEBRATE SKELETON. Common general plan—In several respects—Strongly suggestive of common origin—Details of structure demonstrative of the