PREFACE.
My warmest thanks are due to Mr. Francis Darwin, to Mr. E. B. Poulton (whose interest in the subject here discussed is shown by his share in the translation of Weismann's Essays on Heredity), and to Professor Romanes, for the help afforded by their kindly suggestions and criticisms, and for the advice and recommendation under which this essay is now published. Encouragement from Mr. Francis Darwin is to me the more precious, and the more worthy of grateful recognition, from the fact that my general conclusion that acquired characters are not inherited is at variance with the opinion of his revered father, who aided his great theory by the retention of some remains of Lamarck's doctrine of the inherited effect of habit. I feel as if the son, as representative of his great progenitor, were carrying out the idea of an appreciative editor who writes to me: "We must say that if Darwin were still alive, he would find your arguments of great weight, and undoubtedly would give to them the serious consideration which they deserve." I hope, then, that I may be acquitted of undue presumption in opposing a view sanctioned by the author of the Origin of Species, but already stoutly questioned and firmly rejected by such followers of his as Weismann, Wallace, Poulton, Ray Lankester, and others, to say nothing of its practical rejection by so great an authority on heredity as Francis Galton.
The sociological importance of the subject has already been insisted on in emphatic terms by Mr. Herbert Spencer, and this importance may be even greater than he imagined.
Civilization largely sets aside the harsh but ultimately salutary action of the great law of Natural Selection without providing an efficient substitute for preventing degeneracy. The substitute on which moralists and legislators rely—if they think on the matter at all—is the cumulative inheritance of the beneficial effects of education, training, habits, institutions, and so forth—the inheritance, in short, of acquired characters, or of the effects of use and disuse. If this substitute is but a broken reed, then the deeper thinkers who gradually teach the teachers of the people, and ultimately even influence the legislators and moralists, must found their systems of morality and their criticisms of social and political laws and institutions and customs and ideas on the basis of the Darwinian law rather than on that of Lamarck.
Looking forward to the hope that the human race may become consciously and increasingly master of itself and of its destiny, and recognizing the Darwinian principle of the selection of the fittest as the only means of preventing the moral and physical degeneracy which, like an internal dry rot, has hitherto been the besetting danger of all civilizations, I desire that the thinkers who mould the opinions of mankind shall not be led astray from the true path of enduring progress and happiness by reliance on fallacious beliefs which will not bear examination. Such, at least, is the feeling or motive which has prompted me to devote much time and thought to a difficult but important inquiry in a debatable region of inference and conjecture, where (I am afraid) evidence on either side can never be absolutely conclusive, and where, especially, the absolute demonstration of a universal negative cannot reasonably be expected.
CONTENTS.
| PREFACE | PAGE [v] |
| IMPORTANCE AND BEARING OF THE INQUIRY | [1] |
| SPENCER'S EXAMPLES AND ARGUMENTS | [6-44] |
| Diminution of the Jaws | [6] |
| Diminished Biting Muscles of Lap-Dogs | [12] |
| Crowded Teeth | [14] |
| Blind Cave-Crabs | [17] |
| No Concomitant Variation from Concomitant Disuse | [17] |
| The Giraffe, and Necessity for Concomitant Variation | [18] |
| Alleged Ruinous Effects of Natural Selection | [23] |
| Adverse Case of Neuter Insects | [24] |
| Æsthetic Faculties | [29] |
| Lack of Evidence | [34] |
| Inherited Epilepsy in Guinea-Pigs | [35] |
| Inherited Insanity and Nervous Disorders | [36] |
| Individual and Transmissible Type not Modified Alike | [40] |
| DARWIN'S EXAMPLES | [45-100] |
| Reduced Wings of Birds of Oceanic Islands | [49] |
| Drooping Ears and Deteriorated Instincts | [53] |
| Wings and Legs of Ducks and Fowls | [55] |
| Pigeons' Wings | [62] |
| Shortened Breast-Bone in Pigeons | [64] |
| Shortened Feet in Pigeons | [70] |
| Shortened Legs of Rabbits | [70] |
| Blind Cave-Animals | [72] |
| Inherited Habits | [73] |
| Tameness of Rabbits | [76] |
| Modifications Obviously Attributable to Selection | [82] |
| Similar Effects of Natural Selection and Use-Inheritance | [83] |
| Inferiority of Senses in Europeans | [85] |
| Short-Sight in Watchmakers and Engravers | [85] |
| Larger Hands of Labourers' Infants | [87] |
| Thickened Sole in Infants | [88] |
| A Source of Mental Confusion | [91] |
| Weakness of Use-Inheritance | [94] |
| INHERITED INJURIES | [101-118] |
| Inherited Mutilations | [101] |
| The Motmot's Tail | [110] |
| Other Inherited Injuries Mentioned by Darwin | [111] |
| Quasi-Inheritance | [116] |
| MISCELLANEOUS CONSIDERATIONS | [119-143] |
| True Relation of Parents and Offspring | [119] |
| Inverse Inheritance | [123] |
| Early Origin of the Ova | [124] |
| Marked Effects of Use and Disuse on the Individual | [126] |
| Would Natural Selection Favour Use-Inheritance? | [127] |
| Use-Inheritance an Evil | [128] |
| Varied Effects of Use and Disuse | [134] |
| Use-Inheritance Implies Pangenesis | [137] |
| Pangenesis Improbable | [138] |
| Spencer's Explanation of Use-Inheritance | [141] |
| CONCLUSIONS | [144-156] |
| Use-Inheritance Discredited as Unnecessary, Unproven, and Improbable | [144] |
| Modern Reliance on Use-Inheritance Misplaced | [145] |