viii CONTENTS 



XXV. Genetic Changes in Bisexual Reproduction . . . 219 



^XXVI. Inbreeding and Cross-Breeding 2-27 



4f XXVII. Hybrid Vigor or Heterosis 242 



XXVIII. . Galton's Law of Ancestral Heredity and his Prin- 

 ciple OF Regression 246 



"XXIX. Sex Determination 248 



PART II. EUGENICS 



XXX. Human Crosses 205 



XXXI. Physical and Mental Inheritance in Man ... 271 

 XXXII. Heredity of General Mental Ability, Insanity, 



Epilepsy, and Feeble-Mindedness . 279 



y0 XXXIII. The Possibility and Prospects of Breeding a Better 



Human Race 292 



APPENDIX. Translation of Mendel's Paper. Experiments 



in Plant-Hybridisation 313 



BIBLIOGRAPHY 355 



INDEX 391 



