1 66 CONTINUITY OF THE GERM- PLASM, etc. 



II. The significance of the Polar Bodies .... 216 



1. The egg-cell contains two kinds of idioplasm ; germ-plasm 



and histogenetic nucleoplasm . . . . .217 



2. The expulsion of the polar bodies signifies the removal of 



the histogenetic nucleoplasm ...... 218 



3. Other theories as to the significance of the polar bodies . 218 



4. The modes of occurrence of polar bodies .... 221 



5. Their possible occurrence in male germ-cells . . . 223 



6. There are two kinds of nucleoplasm in the male germ-cells 223 



7. Polar bodies in plants ....... 227 



8. Morphological origin of polar bodies ..... 228 



III. On the nature of Parthenogenesis ..... 229 



1. The phenomena exhibited in the maturation of the &%^ 



are identical in parthenogenetic and sexual development 229 



2. The diff"erence betw^een parthenogenetic and sexual cells 



must be of a quantitative nature ..... 231 



3. The quantity of the germ-plasm determines development . 232 



4. The expulsion of polar bodies depends upon the antago- 



nism between germ-plasm and ovogenetic nucleoplasm 235 



5. Fertilization does not act dynamically .... 236 



6. An insufficient quantity of germ-plasm arrests development 237 



7. Relation of the nucleus to the cell ..... 239 



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



my theory ......... 239 



9. Strasburger's views upon parthenogenesis . . . 242 



10. Parthenogenesis does not depend upon abundant nutrition 244 



11. The indirect causes of sexual and parthenogenetic re- 



production ......... 246 



12. The direct causes ........ 247 



13. Explanation of the formation of nutritive cells . . . 248 



14. Identity of the germ-plasm in male and female germ-cells 251 



Note ............ 255 



I 



