xiv CONTENTS 



CHAPTER XII 



PACE 



HEREDITY AND DEVELOPMENT , . . . . . 412 



i. 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 



i. 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. 

 ii. Conclusion. 



CHAPTER XIV 



SOCIAL ASPECTS OF BIOLOGICAL RESULTS . . , .510 



i. 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 



