xii CONTENTS 



CHAPTER VIII 



PAGE 



SOMATIC MITOSIS AND CHROMOSOME INDIVIDUALITY 143 



Somatic mitosis Preliminary sketch of mitosis Detailed description of 

 the behavior of the chromosomes in somatic mitosis Chromomeres 

 Summary The individuality of the chromosome The frequent persistence 

 of visible chromosome limits in the resting reticulum Prochromosomes 

 Persistence of parental chromosome groups after fertilization Size and 

 shape of chromosomes Chromosome number Discussion and Conclusions 

 Bibliography 8. 



CHAPTER IX 



THE ACHROMATIC FIGURE, CYTOKINESIS, AND THE CELL WALL 175 



The achromatic figure In higher plants In animals Intranuclear 

 figures Origin of the figure The mechanism of mitosis Cytokinesis 

 In thallophytes In microsporocytes In animals Mechanism of furrowing 

 The cell wall The primary wall layer Secondary and tertiary wall 

 layers The physical nature of the cell wall The chemical nature of the 

 cell wall The walls of spores Bibliography 9. 



CHAPTER X 



OTHER MODES OF NUCLEAR DIVISION 202 



Cyanophyceae Protozoa Other cases in plants Amitosis Amitosis and 

 heredity Bibliography 10. 



CHAPTER XI 



THE REDUCTION OF THE CHROMOSOMES 219 



Discovery The stage in the life cycle at which reduction occurs The 

 meaning of reduction Interpretations based on Weismann's theory 

 Somatic and heterotypic mitoses compared Modes of chromosome reduc- 

 tion Scheme A Scheme B Comparison of Schemes A and B Reduction 

 with chromosome tetrads Numerical reduction without qualitative reduc- 

 tion Synapsis, or chromosome conjugation Relationship of the synaptic 

 mates The stage at which conjugation occurs The nature of the synaptic 

 union Chromomeres Other opinions on the heterotypic prophase 

 Bibliography 11. 



CHAPTER XII 



FERTILIZATION 273 



Fertilization in animals The gametes The fusion of the gametes 

 Fertilization in protozoa The physiology of fertilization Fertilization 

 in plants Algse Fungi Bryophytes and pteridophytes Gymnosperms 

 Angiosperms Chromosome behavior Endosperm Bibliography 12. 



CHAPTER XIII 



APOGAMY, APOSPORY, AND PARTHENOGENESIS 311 



Apogamy Apospory Parthenogenesis in animals Bibliography 13. 



CHAPTER XIV 



THE ROLE OF THE CELL ORGANS IN HEREDITY 323 



The law of genetic continuity The role of the nucleus The promorphology 

 of the ovum Plastid inheritance Aleurone inheritance General con- 

 clusions. 



