TABLE OF CONTENTS Xlii 



PAGE 



E. Reduction in Unicellular Forms .198 



F. Divergent Accounts of Reduction I0 ^ 



i. Formation of Tetrads by Conjugation ....... 199 



i;. Maturation of Parthenogenetic Eggs 202 



H. Summary and Conclusion ......... 20? 



Appendix 208 



1. Accessory Cells of the Testis 208 



2. A mitosis in the Early Sex-cells 209 



Literature, V 2 og 



CHAPTER VI 

 SOME PROBLEMS OF CELL-ORGANIZATION 



A. The Nature of Cell-organs . . . . 211 



B. Structural Basis of the Cell 212 



i. Nucleus and Cytoplasm 214 



C. Morphological Composition of the Nucleus 215 



i. The Chromatin . . . . . . . . . . . .215 



() Hypothesis of the Individuality of the Chromosomes . . .215 



(/?) Composition of the Chromosomes 221 



D. Chromatin, Linin, and the Cytoreticulum . . . . . . . 223 



E. The Centrosome 224 



F. The Archoplasmic Structures 229 



1. Asters and Spindle ' 229 



2. The Attraction-sphere 232 



G. Summary and Conclusion 236 



Literature, VI. 237 



CHAPTER VII 

 SOME ASPECTS OF CELL-CHEMISTRY AND CELL-PHYSIOLOGY 



A. Chemical Relations of Nucleus and Cytoplasm . . 238 



1. The Proteids and their Allies 239 



2. The Nuclein Series 240 



3. Staining-reactions of the Nuclein Series ....... 242 



B. Physiological Relations of Nucleus and Cytoplasm 248 



1. Experiments on Unicellular Organisms 248 



2. Position and Movements of the Nucleus 252 



3. The Nucleus in Mitosis 256 



4. The Nucleus in Fertilization 257 



5. The Nucleus in Maturation ......... 259 



C. The Centrosome 259 



D. Summary and Conclusion . 261 



Literature, VII. 263 



CHAPTER VIII 

 CELL-DIVISION AND DEVELOPMENT 



A. Geometrical Relations of Cleavage-forms 265 



B. Promorphological Relations of Cleavage 278 



1. Promorphology of the Ovum . 278 



() Polarity and the Egg-axis 278 



(<) Axial Relations of the Primary Cleavage-planes .... 280 



(<:) Other Promorphological Characters of the Ovum .... 282 



2. Meaning of the Promorphology of the Ovum ...... 285 



