CONTENTS 



CHAPTSR PAGE 



I. Introduction 13 ^ 



II. Reprodtjction Among Animals and Plants 20 



III. The Mechanism op Reproduction '. 36 



IV. The Mechanism of Heredity 50 • 



V. Mathematical Considerations op Inbreeding 80 



VI. Inbreeding Experiments with Animals and Plants 100 



VII. Htbrid Vigor or Hjbterosis 141 • 



VIII. Conceptions as to the Cause op Hybrid Vigor 164 



IX. STEMLiry AND Its Relation to Inbreeding and Cross-brbbdinq 188 



X. The R6le op Inbreeding and Outbreeding in Evolution. . . 195 . 



XI. The Value op Inbreeding and Outbreeding in Plant and 



Animal Improvement 210 ■ 



XII. Inbreeding and Outbreeding in Man; Their Effect on 



THE Individual 226 • 



r 



XIII. The Intermingling op Races and National Stamina 245 



Literature 266 



