CONTENTS 



CHAPTER I 



PACK 



HEREDITY AND INHERITANCE : DEFINED AND ILLUS- 

 TRATED I 



I. Importance of the Study of Heredity. 2. What the Terms 

 Mean. 3. Heredity and Inheritance in Relation to other Bio- 

 hgical Concepts. 4. A Question of Words. 5. The Problems 

 Illustrated. 6. Denials of Inheritance. 



CHAPTER II 

 THE PHYSICAL BASIS OF INHERITANCE . . . .26 



i. What is true in the Great Majority of Cases. 2. Diverse 

 Modes of Reproduction. 3. The Hereditary Relation in Uni- 

 cellular Organisms. 4. The Hereditary Relation in the Asexual 

 Multiplication of Multicellular Organisms. 5. Nature and 

 Origin of the Germ-cells. 6. Maturation of ' the Germ- cells. 

 7. Amphimixis and the Dual Nature of Inheritance in Sexual 

 Reproduction. 8. Inheritance in Parthenogenesis. 9. Wherein 

 the Physical Basis precisely consists. 



CHAPTER III 

 HEREDITY AND VARIATION 66 



i. Persistence and Novelty. 2. The Tendency to Breed 

 True. 3. Different Kinds of Organic Change. 4. Classifica- 

 tion and Illustration of Variations. 5. Fluctuating Variations. 

 6. Discontinuous Variations. 7. De Vries on Fluctuations and 

 Mutations. 8. Causes of Variation. 



