12. The regular cyclical development of the idioplasm 199 founded upon phylogeny by Nägeli 13. It follows from phyletic considerations that the germ- 201 cells have not arisen at the end of ontogeny 14. They originally arose at the beginning of ontogeny, but 202 at a later period the time of their origin was displaced 15. A continuity of the germ-cells does not now exist in 205 most cases 16. But there is a continuity of the germ-plasm 205 17. Strasburger’s objection to my supposition that the germ- 209 plasm passes along distinct routes 18. The cell-body may remain unchanged when the nucleus is 210 changed 19. It is conceivable that all somatic nuclei may contain 211 some germ-plasm II. The Significance of the Polar Bodies 212 1. The egg-cell contains two kinds of idioplasm; germ-plasm 213 and histogenetic nucleoplasm 2. The expulsion of the polar bodies signifies the removal 214 of the histogenetic nucleoplasm 3. Other theories as to the significance of the polar 214 bodies 4. The modes of occurrence of polar bodies 217 5. Their possible occurrence in male germ-cells 219 6. There are two kinds of nucleoplasm in the male germ- 219 cells 7. Polar bodies in plants 222 8. Morphological origin of polar bodies 223 III. On the Nature of Parthenogenesis 225 1. The phenomena exhibited in the maturation of the egg are 225 identical in parthenogenetic and sexual development 2. The difference between parthenogenetic and sexual cells 226 must be of a quantitative nature 3. The quantity of the germ-plasm determines development 227 4. The expulsion of polar bodies depends upon the 230 antagonism between germ-plasm and ovogenetic nucleoplasm 5. Fertilization does not act dynamically 231 6. An insufficient quantity of germ-plasm arrests 232 development 7. Relation of the nucleus to the cell 234 8. The case of the bee does not constitute any objection to 234 my theory 9. Strasburger’s views upon parthenogenesis 237 10. Parthenogenesis does not depend upon abundant nutrition 239 11. The indirect causes of sexual and parthenogenetic 241 reproduction 12. The direct causes 242 13. Explanation of the formation of nutritive cells 243 14. Identity of the germ-plasm in male and female germ-cells 246 Note 249