CONTINUITY OF THE GERM-PLASM, &c.
CONTENTS.
| Introduction | 165 |
| I. The Germ-Plasm | 174 |
| 1. | Historical development of the theory as to the localization of the germ-plasm in the nucleus | 174 |
| 2. | Nägeli’s ‘idioplasm’ is not identical with Weismann’s ‘germ-plasm’ | 180 |
| 3. | A retransformation of somatic idioplasm into germ-idioplasm does not take place | 183 |
| 4. | Confirmation of the theory as to the significance of the nuclear substance afforded by Nussbaum’s and Gruber’s experiments on regeneration in Infusoria | 185 |
| 5. | The nucleoplasm changes during ontogeny according to a certain law | 186 |
| 6. | The identity of the daughter-nuclei produced by indirect nuclear division, as assumed by Strasburger, is not necessary for my theory | 187 |
| 7. | The gradual decrease in complexity of the structure of the nucleus during ontogeny | 190 |
| 8. | Nägeli’s view on the germs (‘Anlagen’) in the idioplasm | 192 |
| 9. | The manner in which germ-cells arise from somatic cells | 194 |
| 10. | ’Embryonic’ cells in the mature organism | 196 |
| 11. | The rule of probability is against a retransformation of somatic idioplasm into germ-plasm | 198 |
| 12. | The regular cyclical development of the idioplasm founded upon phylogeny by Nägeli | 199 |
| 13. | It follows from phyletic considerations that the germ-cells have not arisen at the end of ontogeny | 201 |
| 14. | They originally arose at the beginning of ontogeny, but at a later period the time of their origin was displaced | 202 |
| 15. | A continuity of the germ-cells does not now exist in most cases | 205 |
| 16. | But there is a continuity of the germ-plasm | 205 |
| 17. | Strasburger’s objection to my supposition that the germ-plasm passes along distinct routes | 209 |
| 18. | The cell-body may remain unchanged when the nucleus is changed | 210 |
| 19. | It is conceivable that all somatic nuclei may contain some germ-plasm | 211 |
| II. The Significance of the Polar Bodies | 212 |
| 1. | The egg-cell contains two kinds of idioplasm; germ-plasm and histogenetic nucleoplasm | 213 |
| 2. | The expulsion of the polar bodies signifies the removal of the histogenetic nucleoplasm | 214 |
| 3. | Other theories as to the significance of the polar bodies | 214 |
| 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 Parthenogenesis | 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. | Relation 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 |