164 CONTINUITY OF THE GEKM-PLASM, &C. CONTENTS. 



PAGE 



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-cells . . .219 



7. Polar bodies in plants 222 



8. Morphological origin of polar bodies 223 



III. ON THE NATURE OF PABTHENOGENESIS 225 



1. The phenomena exhibited in the maturation of the egg are identical 



in parthenogenetic and sexual development . . . . .225 



2. The difference between parthenogenetic and sexual cells must be of a 



quantitative nature 226 



3. The quantity of the germ-plasm determines development . . .227 



4. The expulsion of polar bodies depends upon 'the antagonism between 



germ-plasm and ovogenetic nucleoplasm 230 



5. Fertilization does not act dynamically 231 



6. An insufficient quantity of germ-plasm arrests development . . 232 



7. Eelation of the nucleus to the cell 234 



8. The case of the bee does not constitute any objection to my theory . 234 



9. Strasburger's views upon parthenogenesis 237 



10. Parthenogenesis does not depend upon abundant nutrition . . -239 



11. The indirect causes of sexual and parthenogenetic reproduction . . 241 



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 



