xiv CONTENTS 



CHAPTER XII 



PAGE 



HEREDITY AND DEVELOPMENT . 412 



§ 1. Theories of Development. § 2. Weismann's Theory of the 

 Germ-Plasm. § 3. Note on Rival Theories. § 4. Weismann's 

 Theory of Germinal Selection. 



CHAPTER XIII 



HEREDITY AND SEX 472 



§ 1. Relations between Sex and Inheritance. § 2. The Deter- 

 mination of Sex. § 3. Different Ways of Attacking the Problem. 

 § 4. Classification of Theories. § 5. First Theory : Environment 

 affects Offspring. § 6. Second Theory : Fertilisation is Decisive. 

 § 7. Third Theory : Two Kinds of Germ-Cells. § 8. Fourth 

 Theory : Maleness and Femaleness are Mendelian Characters. 

 § 9. Fifth Theory : Nurtural Influences operate on the Germ-Cells 

 through the Parents. § 10. Another Way of looking at the Facts. 

 § 11. Conclusion. 



CHAPTER XIV 



SOCIAL ASPECTS OF BIOLOGICAL RESULTS .... 510 



§ 1. Relations of Biology and Sociology. § 2. The Chief Value 



of the Sociological Appeal to Biology. § 3. Originative Factors 



in Evolution. § 4. Social Aspects of Heredity. § 5. Directive 

 Factors in Evolution. 



BIBLIOGRAPHY .... ..... 543 



SUBJECT-INDEX TO BIBLIOGRAPHY 605 



INDEX . . ... • : ■ « ■ 619 I 



