For the illustrations, other than those that are original, the author is indebted to the _Journal of the American Medical Association_, _Dental Cosmos_, _The International Dental Journal_, _The St. Louis Clinical Record_, to M. Félix Alcan, and to the officers of the New York State Reformatory and Illinois State Reformatory, Drs. Geo. T. Carpenter, W. A. Pusey, F. S. Coolidge, Ch. Féré, Zuckerkandl, John E. Greves, Amsterdam; Ernst Sjoberg, Stockholm; Bastian, J. G. Kiernan, E. C. Spitzka, John Ridlon, James W. Walker, and Ignatius Donnelly. E. S. T. CONTENTS CHAP. PAGE I. INTRODUCTION 1 II. THE STIGMATA OF DEGENERACY 27 III. HEREDITY AND ATAVISM 40 IV. CONSANGUINEOUS AND NEUROTIC INTERMARRIAGES 79 V. INTERMIXTURE OF RACES 92 VI. TOXIC AGENTS 104 VII. CONTAGIOUS AND INFECTIOUS DISEASES 121 VIII. CLIMATE, SOIL, AND FOOD 130 IX. SCHOOL STRAIN 150 X. THE DEGENERATE CRANIUM 161 XI. THE DEGENERATE FACE AND NOSE 177 XII. DEGENERACY OF THE LIP PALATE, EYE, AND EAR 196 XIII. THE DEGENERATE TEETH AND JAWS 219 XIV. DEGENERACY OF THE BODY 258 XV. DEGENERACY IN REVERSIONAL TENDENCIES 282 XVI. DEGENERACY OF THE BRAIN 294 XVII. DEGENERACY OF MENTALITY AND MORALITY 315 XVIII. CONCLUSIONS 346 INDEX OF AUTHORS 363 INDEX OF SUBJECTS 367 LIST OF ILLUSTRATIONS FIG. PAGE DWARFISM AND GIANTISM (_Journal of American Medical Association_) _Frontispiece_ 1. ANTE-CHRISTIAN IRISH PIPES (Donnelly, _Atlantis_) 111 2. ANTE-COLUMBIAN PIPES FROM SCULPTURE AT STRATFORD-ON-AVON (Donnelly, _Atlantis_) 112 3-6. CHANGES IN SKULL TYPES (_Original_) 134 7. WANT OF UNION IN FRONTAL SUTURE (Dr. Greves, Amsterdam) 163 8. STIGMATA OF DEGENERATE CRANIUM (Original) 165 9. HYDROCEPHALY (Dr. Ernst Sjöberg, Stockholm) 166 10. KEPHALONES (Dr. Ernst Sjöberg, Stockholm) 167 11. MICROCEPHALY (Dr. Ernst Sjöberg, Stockholm) 168 12. DOLICHOCEPHALY (Barnard Davis) 169 13. SPHENOCEPHALY (New York State Reformatory) 170 14. BRACHYCEPHALY (Barnard Davis) 171